Re-Emergence of Rift Valley Fever in Madagascar

Centers for Disease Control (CDC) Podcasts

2010-05-27

This podcast describes the re-emergence of Rift Valley Fever in Madagascar during two rainy seasons in 2008 and 2009. CDC epidemiologist Dr. Pierre Rollin discusses what researchers learned about the outbreak and about infections in the larger population in Madagascar.  Created: 5/27/2010 by National Center for Emerging and Zoonotic Infectious Diseases (NCEZID).   Date Released: 5/27/2010.

The regional structure of the Red Sea Rift revised

Science.gov (United States)

Augustin, Nico; van der Zwan, Froukje M.; Devey, Colin W.; Brandsdóttir, Bryndís

2017-04-01

The Red Sea Rift has, for decades, been considered a text book example of how young ocean basins form and mature. Nevertheless, most studies of submarine processes in the Red Sea were previously based on sparse data (mostly obtained between the late 1960's and 1980's) collected at very low resolution. This low resolution, combined with large gaps between individual datasets, required large interpolations when developing geological models. Thus, these models generally considered the Red Sea Rift a special case of young ocean basement formation, dividing it from North to South into three zones: a continental thinning zone, a "transition zone" and a fully developed spreading zone. All these zones are imagined, in most of the models, to be separated by large transform faults, potentially starting and ending on the African and Arabian continental shields. However, no consensus between models e.g. about the locations (or even the existence) of major faults, the nature of the transition zone or the extent of oceanic crust in the Red Sea Rift has been reached. Recently, high resolution bathymetry revealed detailed seafloor morphology as never seen before from the Red Sea, very comparable to other (ultra)slow spreading mid-ocean ridges such as the Gakkel Ridge, the Mid-Atlantic Ridge and SW-Indian Ridge, changing the overall picture of the Red Sea significantly. New discoveries about the extent, movement and physical properties of submarine salt deposits led to the Red Sea Rift being linked to the young Aptian-age South Atlantic. Extensive crosscutting transform faults are not evident in the modern bathymetry data, neither in teleseismic nor vertical gravity gradient data and comparisons to Gakkel Ridge and the SW-Indian Ridge suggest that the Red Sea is much simpler in terms of structural geology than was previously thought. Complicated tectonic models do not appear necessary and there appears to be large areas of oceanic crust under the Red Sea salt blankets. Based on

Geodynamic modelling of the rift-drift transition: Application to the Red Sea

Science.gov (United States)

Fierro, E.; Schettino, A.; Capitanio, F. A.; Ranalli, G.

2017-12-01

The onset of oceanic accretion after a rifting phase is generally accompanied by an initial fast pulse of spreading in the case of volcanic margins, such that the effective spreading rate exceeds the relative far-field velocity between the two plates for a short time interval. This pulse has been attributed to edge-driven convention (EDC), although our numerical modelling shows that the shear stress at the base of the lithosphere cannot exceed 1 MPa. In general, we have developed a 2D numerical model of the mantle instabilities during the rifting phase, in order to determine the geodynamic conditions at the rift-drift transition. The model was tested using Underworld II software, variable rheological parameters, and temperature and stress-dependent viscosity. Our results show an increase of strain rates at the top of the lithosphere with the lithosphere thickness as well as with the initial width of the margin up to 300 km. Beyond this value, the influence of the initial rift width can be neglected. An interesting outcome of the numerical model is the existence of an axial zone characterized by higher strain rates, which is flanked by two low-strain stripes. As a consequence, the model suggests the existence of an area of syn-rift compression within the rift valley. Regarding the post-rift phase, we propose that at the onset of a seafloor spreading, a phase of transient creep allows the release of the strain energy accumulated in the mantle lithosphere during the rifting phase, through anelastic relaxation. Then, the conjugated margins would be subject to post-rift contraction and eventually to tectonic inversion of the rift structures. To explore the tenability of this model, we introduce an anelastic component in the lithosphere rheology, assuming both the classical linear Kelvin-Voigt rheology and a non-linear Kelvin model. The non-linear model predicts viable relaxation times ( 1-2Myrs) to explain the post-rift tectonic inversion observed along the Arabian

Vertical transmission of Rift Valley Fever Virus without detectable maternal viremia

NARCIS (Netherlands)

Antonis, A.F.G.; Kortekaas, J.A.; Kant-Eenbergen, H.C.M.; Vloet, R.P.M.; Vogel-Brink, A.; Stockhofe, N.; Moormann, R.J.M.

2013-01-01

Rift Valley fever virus (RVFV) is a zoonotic bunyavirus that causes abortions in domesticated ruminants. Sheep breeds exotic to endemic areas are reportedly the most susceptible to RVFV infection. Within the scope of a risk assessment program of The Netherlands, we investigated the susceptibility of

Seismic imaging of the metamorphism of young sediment into new crystalline crust in the actively rifting Imperial Valley, California

Science.gov (United States)

Han, Liang; Hole, John; Stock, Joann; Fuis, Gary S.; Williams, Colin F.; Delph, Jonathan; Davenport, Kathy; Livers, Amanda

2016-01-01

Plate-boundary rifting between transform faults is opening the Imperial Valley of southern California and the rift is rapidly filling with sediment from the Colorado River. Three 65–90 km long seismic refraction profiles across and along the valley, acquired as part of the 2011 Salton Seismic Imaging Project, were analyzed to constrain upper crustal structure and the transition from sediment to underlying crystalline rock. Both first arrival travel-time tomography and frequency-domain full-waveform inversion were applied to provide P-wave velocity models down to ∼7 km depth. The valley margins are fault-bounded, beyond which thinner sediment has been deposited on preexisting crystalline rocks. Within the central basin, seismic velocity increases continuously from ∼1.8 km/s sediment at the surface to >6 km/s crystalline rock with no sharp discontinuity. Borehole data show young sediment is progressively metamorphosed into crystalline rock. The seismic velocity gradient with depth decreases approximately at the 4 km/s contour, which coincides with changes in the porosity and density gradient in borehole core samples. This change occurs at ∼3 km depth in most of the valley, but at only ∼1.5 km depth in the Salton Sea geothermal field. We interpret progressive metamorphism caused by high heat flow to be creating new crystalline crust throughout the valley at a rate comparable to the ≥2 km/Myr sedimentation rate. The newly formed crystalline crust extends to at least 7–8 km depth, and it is shallower and faster where heat flow is higher. Most of the active seismicity occurs within this new crust.

Seismic imaging of the metamorphism of young sediment into new crystalline crust in the actively rifting Imperial Valley, California

Science.gov (United States)

Han, Liang; Hole, John A.; Stock, Joann M.; Fuis, Gary S.; Williams, Colin F.; Delph, Jonathan R.; Davenport, Kathy K.; Livers, Amanda J.

2016-11-01

Plate-boundary rifting between transform faults is opening the Imperial Valley of southern California and the rift is rapidly filling with sediment from the Colorado River. Three 65-90 km long seismic refraction profiles across and along the valley, acquired as part of the 2011 Salton Seismic Imaging Project, were analyzed to constrain upper crustal structure and the transition from sediment to underlying crystalline rock. Both first arrival travel-time tomography and frequency-domain full-waveform inversion were applied to provide P-wave velocity models down to ˜7 km depth. The valley margins are fault-bounded, beyond which thinner sediment has been deposited on preexisting crystalline rocks. Within the central basin, seismic velocity increases continuously from ˜1.8 km/s sediment at the surface to >6 km/s crystalline rock with no sharp discontinuity. Borehole data show young sediment is progressively metamorphosed into crystalline rock. The seismic velocity gradient with depth decreases approximately at the 4 km/s contour, which coincides with changes in the porosity and density gradient in borehole core samples. This change occurs at ˜3 km depth in most of the valley, but at only ˜1.5 km depth in the Salton Sea geothermal field. We interpret progressive metamorphism caused by high heat flow to be creating new crystalline crust throughout the valley at a rate comparable to the ≥2 km/Myr sedimentation rate. The newly formed crystalline crust extends to at least 7-8 km depth, and it is shallower and faster where heat flow is higher. Most of the active seismicity occurs within this new crust.

Seroprevalence of Sheep and Goat Pox, Peste Des Petits Ruminants and Rift Valley Fever in Saudi Arabia.

Science.gov (United States)

Boshra, Hani; Truong, Thang; Babiuk, Shawn; Hemida, Maged Gomaa

2015-01-01

Sheep and goat pox, peste des petits ruminants and Rift Valley fever are important diseases of small ruminant livestock. Sheep and goat pox, along with peste des petits ruminants, are endemic throughout most of Africa, Asia and the Middle East. Whereas Rift Valley fever is endemic in Africa, outbreaks in the Middle East have been reported over the past decade, including the Arabian Peninsula. Saudi Arabia is a major importer of livestock, and understanding the prevalence of these viral infections would be useful for disease control. In this study, sera from sheep and goats were collected from 3 regions in Saudi Arabia. They were evaluated for antibodies specific to sheep and goat pox, peste des petits ruminants and Rift Valley fever by virus neutralization assays. To the best of our knowledge, this is the first study to evaluate the seroprevalence of these viruses in sheep and goats.

Seroprevalence of Sheep and Goat Pox, Peste Des Petits Ruminants and Rift Valley Fever in Saudi Arabia.

Directory of Open Access Journals (Sweden)

Hani Boshra

Full Text Available Sheep and goat pox, peste des petits ruminants and Rift Valley fever are important diseases of small ruminant livestock. Sheep and goat pox, along with peste des petits ruminants, are endemic throughout most of Africa, Asia and the Middle East. Whereas Rift Valley fever is endemic in Africa, outbreaks in the Middle East have been reported over the past decade, including the Arabian Peninsula. Saudi Arabia is a major importer of livestock, and understanding the prevalence of these viral infections would be useful for disease control. In this study, sera from sheep and goats were collected from 3 regions in Saudi Arabia. They were evaluated for antibodies specific to sheep and goat pox, peste des petits ruminants and Rift Valley fever by virus neutralization assays. To the best of our knowledge, this is the first study to evaluate the seroprevalence of these viruses in sheep and goats.

Eradicating tsetse from the Southern Rift Valley of Ethiopia

International Nuclear Information System (INIS)

2003-01-01

Farming activities in Ethiopia, as in much of sub-Saharan Africa, are restricted by the presence of tsetse flies (Glossina spp.). These carry the livestock and human disease, trypanosomosis, which severely affects agricultural production and human well-being. In collaboration with the Ethiopian authorities, the International Atomic Energy Agency is sponsoring a Sterile Insect Technique (SIT) programme to eradicate tsetse from the Southern Rift Valley of Ethiopia. (IAEA)

New structural/tectonical model and its implication on hydrological thinking and groundwater management - the Lake Tiberias, Jordan Rift Valley

Science.gov (United States)

Inbar, Nimrod; Magri, Fabien; Yellin-Dror, Annat; Rosenthal, Eliahu; Möller, Peter; Siebert, Christian; Guttman, Josef

2014-05-01

Lake Tiberias is a fresh water lake located at the Kinneret basin which is approximately 30 km long and 10 km wide. It comprises a link in the chain of pull-apart basins that characterizes the structure of the conspicuous Jordan Rift Valley (JRV). The basin surface is about 200 m below mean sea level (msl) and basin-fill attains a thickness of up to 8 km. Until recently, studies focused mainly on the upper strata of basin fill. Consequently, a complete three dimensional geological model, including clear view of the tectonic framework at the Kinneret Basin was incomplete. This situation imposes great difficulty in understanding the local hydrological system and as consequence enforce constrains on groundwater management of the regional aquifers that flows towards the lake. A recently proposed structural/tectonical model (Inbar, 2012) enables revaluation of several geohydrological aspects at Sea of Galilee and its surroundings and a new hydrological model based on those findings aims to clarify those aspects with relation to groundwater management. The deep-seated stratigraphical units were seismically studied at the Kinnarot Valley (southern part of Kinneret basin) where sufficient information is available (Inbar, 2012). This study shows the subsidence and northwestward tilting of the basin floor (pre-rift formations) and the flow of thick Late Miocene salt accumulation accordingly. Furthermore, shallower seismic data, collected at the lake itself, shows a suspected salt dome close to the western boundary fault of the basin (Resnikov et al., 2004). Salt flow is now suggested to be a substantial factor in the tectonic play. At the lake surroundings there are several springs and boreholes where brine immerges from an estimated depth of about 2-3 kilometers. Significant differences in brine characteristics raised questions regarding the location of brine traps, flow mechanism and the mixture process between the fresh water and the brine. However, the effect of the

Blood Meal Analysis of Mosquitoes Involved in a Rift Valley fever Outbreak

Science.gov (United States)

Background: Rift Valley fever (RVF) is a zoonosis of domestic ruminants in Africa. Bloodfed mosquitoes collected during the 2006-2007 RVF outbreak in Kenya were analyzed to determine the virus infection status and animal source of the bloodmeals. Bloodmeals from individual mosquito abdomens were sc...

Performance assessment of smallholder irrigation in the Central Rift Valley of Ethiopia

NARCIS (Netherlands)

Halsema, van G.E.; Lencha, B.K.; Assefa, M.; Hengsdijk, H.; Wesseler, J.H.H.

2011-01-01

The recent increase in smallholder irrigation schemes in the Central Rift Valley of Ethiopia has been associated with the overexploitation of water resources, while the economic viability of these schemes has been questioned. This paper assesses water use efficiencies of the Haleku Irrigation Scheme

Wolbachia Effects on Rift Valley Virus Infection in Culex tarsalis Mosquitoes

Science.gov (United States)

2017-04-25

Wolbachia density in mosquitoes. 109" 110" Materials and Methods 111" Ethics statement 112" TR-17-113 Mosquitoes were maintained on commercially available...fever virus. 379" Vet Med Today. 2009; 883–893. 380" 29. Wilson M. Rift Valley fever virus ecology and the epidemiology of disease emergence. 381

Geodetic constraints on continental rifting along the Red Sea

Science.gov (United States)

Reilinger, R.; McClusky, S.; Arrajehi, A.; Mahmoud, S.; Rayan, A.; Ghebreab, W.; Ogubazghi, G.; Al-Aydrus, A.

2006-12-01

We are using the Global Positioning System (GPS) to monitor and quantify patterns and rates of tectonic and magmatic deformation associated with active rifting of the continental lithosphere and the transition to sea floor spreading in the Red Sea. Broad-scale motions of the Nubian and Arabian plates indicate coherent plate motion with internal deformation below the current resolution of our measurements (~ 1-2 mm/yr). The GPS-determined Euler vector for Arabia-Nubia is indistinguishable from the geologic Euler vector determined from marine magnetic anomalies, and Arabia-Eurasia relative motion from GPS is equal within uncertainties to relative motion determined from plate reconstructions, suggesting that Arabia plate motion has remained constant (±10%) during at least the past ~10 Ma. The approximate agreement between broad-scale GPS rates of extension (i.e., determined from relative plate motions) and those determined from magnetic anomalies along the Red Sea rift implies that spreading in the central Red Sea is primarily confined to the central rift (±10-20%). Extension appears to be more broadly distributed in the N Red Sea and Gulf of Suez where comparisons with geologic data also indicate a relatively recent (between 500 and 125 kyr BP) change in the motion of the Sinai block that is distinct from both Nubia and Arabia. In the southern Red Sea, GPS results are beginning to define the motion of the "Danakil micro-plate". We investigate and report on a model involving CCW rotation of the Danakil micro-plate relative to Nubia and magmatic inflation below the Afar Triple Junction that is consistent with available geodetic constraints. Running the model back in time suggests that the Danakil micro-plate has been an integral part of rifting/triple junction processes throughout the history of separation of the Arabian and Nubian plates. On the scale of Nubia-Arabia-Eurasia plate interactions, we show that new area formed at spreading centers roughly equals that

[Rift Valley fever: sporadic infection of French military personnel outside currently recognized epidemic zones].

Science.gov (United States)

Durand, J P; Richecoeur, L; Peyrefitte, C; Boutin, J P; Davoust, B; Zeller, H; Bouloy, M; Tolou, H

2002-01-01

For three years the arbovirus surveillance unit of the Tropical Medicine Institute of the French Army Medical Corps (French acronym IMTSSA) in Marseille, France has been investigating causes of benign non-malarial febrile syndromes in French military personnel serving outside mainland France. The methodology used in N'Djamena consisted of sending frozen specimens collected concomitant with viremia, to Marseille for culture. During the rainy season of 2001, specimens were collected from a total of 50 febrile soldiers. Cultures allowed isolation and identification of two strains of Rift Valley virus. The risk of contamination exists not only in the field but also in mainland hospital departments treating infected patients. Routine serological diagnosis for Rift Valley fever must be DISCUSSED for all patients in the field or returning from Africa.

An Epidemiological Model of Rift Valley Fever with Spatial Dynamics

Directory of Open Access Journals (Sweden)

Tianchan Niu

2012-01-01

Full Text Available As a category A agent in the Center for Disease Control bioterrorism list, Rift Valley fever (RVF is considered a major threat to the United States (USA. Should the pathogen be intentionally or unintentionally introduced to the continental USA, there is tremendous potential for economic damages due to loss of livestock, trade restrictions, and subsequent food supply chain disruptions. We have incorporated the effects of space into a mathematical model of RVF in order to study the dynamics of the pathogen spread as affected by the movement of humans, livestock, and mosquitoes. The model accounts for the horizontal transmission of Rift Valley fever virus (RVFV between two mosquito and one livestock species, and mother-to-offspring transmission of virus in one of the mosquito species. Space effects are introduced by dividing geographic space into smaller patches and considering the patch-to-patch movement of species. For each patch, a system of ordinary differential equations models fractions of populations susceptible to, incubating, infectious with, or immune to RVFV. The main contribution of this work is a methodology for analyzing the likelihood of pathogen establishment should an introduction occur into an area devoid of RVF. Examples are provided for general and specific cases to illustrate the methodology.

Analysis of Adoption Spell of Hybrid Maize in the Central Rift Valley ...

African Journals Online (AJOL)

This paper estimates farm household level determinants of the speed of adoption of hybrid maize in the central rift valley of Ethiopia in the framework of the dynamic time on cross-sectional data. Descriptive statistics and duration model were used to study the objectives of the study. The results from descriptive analysis ...

Mosquito host choices on livestock amplifiers of Rift Valley fever virus in Kenya

Science.gov (United States)

Animal hosts may vary in their attraction and acceptability as components of the host location process for assessing biting rates of vectors and risk of exposure to pathogens. However, these parameters remain poorly understood for mosquito vectors of the Rift Valley fever (RVF), an arboviral disease...

Single-particle cryo-electron microscopy of Rift Valley fever virus

OpenAIRE

Sherman, Michael B.; Freiberg, Alexander N.; Holbrook, Michael R.; Watowich, Stanley J.

2009-01-01

Rift Valley fever virus (RVFV; Bunyaviridae; Phlebovirus) is an emerging human veterinary pathogen causing acute hepatitis in ruminants and has the potential to Single-particle cryo-EM reconstruction of RVFV MP-12 hemorrhagic fever in humans. We report a three-dimensional reconstruction of RVFV vaccine strain MP-12 (RVFV MP-12) by cryo-electron microcopy using icosahedral symmetry of individual virions. Although the genomic core of RVFV MP-12 is apparently poorly ordered, the glycoproteins on...

Acid-activated structural reorganization of the Rift Valley fever virus Gc fusion protein

NARCIS (Netherlands)

Boer, de S.M.; Kortekaas, J.A.; Spel, L.; Rottier, P.J.M.; Moormann, R.J.M.; Bosch, B.J.

2012-01-01

Entry of the enveloped Rift Valley fever virus (RVFV) into its host cell is mediated by the viral glycoproteins Gn and Gc. We investigated the RVFV entry process and its pH-dependent activation mechanism in particular using our recently developed nonspreading RVFV particle system. Entry of the virus

Sediment budget and tectonic evolution of the Meuse catchment in the Ardennes and the Roer Valley Rift System

NARCIS (Netherlands)

Balen, R.T. van; Houtgast, R.F.; Wateren, F.M. van der; Berghe, J. van den; Bogaart, P.W.

2000-01-01

The Meuse river system is located in the northeastern part of the Paris Basin, the Ardennes, and the Roer Valley Rift System (RVRS). The Meuse river system developed during the uplift of the Ardennes since the Eocene and it was affected by renewed rifting of the RVRS starting in the Late Oligocene.

Sediment budget and tectonic evolution of the Meuse catchment in the Ardennes and the Roer Valley Rift System.

NARCIS (Netherlands)

van Balen, R.T.; Houtgast, R.F.; van der Wateren, F.M.; Vandenberghe, J.; Bogaart, P.W.

2000-01-01

The Meuse river system is located in the northeastern part of the Paris Basin, the Ardennes, and the Roer Valley Rift System (RVRS). The Meuse river system developed during the uplift of the Ardennes since the Eocene and it was affected by renewed rifting of the RVRS starting in the Late Oligocene.

A Systematic Scoping Study of the Socio-Economic Impact of Rift Valley Fever

NARCIS (Netherlands)

Peyre, M.; Chevalier, V.; Abdo-Salem, S.; Velthuis, A.; Antoine-Moussiaux, N.; Thiry, E.; Roger, F.

2015-01-01

Rift Valley fever (RVF) is a severe mosquito-borne disease affecting humans and domestic ruminants. RVF virus has been reported in most African countries, as well as in the Arabic Peninsula. This paper reviews the different types of socio-economic impact induced by RVF disease and the attempts to

Post-rift deformation of the Red Sea Arabian margin

Science.gov (United States)

Zanoni, Davide; Schettino, Antonio; Pierantoni, Pietro Paolo; Rasul, Najeeb

2017-04-01

Starting from the Oligocene, the Red Sea rift nucleated within the composite Neoproterozoic Arabian-Nubian shield. After about 30 Ma-long history of continental lithosphere thinning and magmatism, the first pulse of oceanic spreading occurred at around 4.6 Ma at the triple junction of Africa, Arabia, and Danakil plate boundaries and propagated southward separating Danakil and Arabia plates. Ocean floor spreading between Arabia and Africa started later, at about 3 Ma and propagated northward (Schettino et al., 2016). Nowadays the northern part of the Red Sea is characterised by isolated oceanic deeps or a thinned continental lithosphere. Here we investigate the deformation of thinned continental margins that develops as a consequence of the continental lithosphere break-up induced by the progressive oceanisation. This deformation consists of a system of transcurrent and reverse faults that accommodate the anelastic relaxation of the extended margins. Inversion and shortening tectonics along the rifted margins as a consequence of the formation of a new segment of ocean ridge was already documented in the Atlantic margin of North America (e.g. Schlische et al. 2003). We present preliminary structural data obtained along the north-central portion of the Arabian rifted margin of the Red Sea. We explored NE-SW trending lineaments within the Arabian margin that are the inland continuation of transform boundaries between segments of the oceanic ridge. We found brittle fault zones whose kinematics is consistent with a post-rift inversion. Along the southernmost transcurrent fault (Ad Damm fault) of the central portion of the Red Sea we found evidence of dextral movement. Along the northernmost transcurrent fault, which intersects the Harrat Lunayyir, structures indicate dextral movement. At the inland termination of this fault the evidence of dextral movement are weaker and NW-SE trending reverse faults outcrop. Between these two faults we found other dextral transcurrent

Transmission of Rift Valley fever virus from European-breed lambs to Culex pipiens mosquitoes

NARCIS (Netherlands)

Vloet, Rianka P.M.; Vogels, Chantal B.F.; Koenraadt, Constantianus J.M.; Pijlman, Gorben P.; Eiden, Martin; Gonzales, Jose L.; Keulen, van Lucien J.M.; Wichgers Schreur, Paul J.; Kortekaas, Jeroen

2017-01-01

Background: Rift Valley fever virus (RVFV) is a mosquito-borne bunyavirus of the genus Phlebovirus that is highly pathogenic to ruminants and humans. The disease is currently confined to Africa and the Arabian Peninsula, but globalization and climate change may facilitate introductions of the virus

Relations between tectonics and sedimentation along the Eastern Sardinian margin (Western Tyrrhenian Sea) : from rifting to reactivation

Science.gov (United States)

Gaullier, Virginie; Chanier, Frank; Vendeville, Bruno; Lymer, Gaël; Maillard, Agnès; Thinon, Isabelle; Lofi, Johanna; Sage, Françoise; Giresse, Pierre; Bassetti, Maria-Angela

2014-05-01

salt and its Late Messinian and Early Pliocene brittle overburden. "METYSAR" fieldwork onshore was conducted in the Orosei region and showed that the main present-day Cedrino river follows the trend of a paleo-valley that cuts through the underlying granitic basement and alterites. These deposits, along with the basement, were likely eroded during Messinian times, then reworked during a marine transgression. Micro-fauna in these fine-grained marine sediments are of Upper Pliocene age. The strata dip by 20° to 30° and trend NNE-SSW, a direction which is sub-parallel to the main tectonic structures involved in the rifting of the margin. The tilted Pliocene strata were overlain by volcanic flows, some dating from Upper Pliocene time. Field mapping has evidenced that there was a paleo-topographic relief, trending NNE-SSW, that controlled the sediment deposition. These results indicate that the post-Messinian tectonic activity, which is also visible offshore, controlled the sedimentary architecture and the paleogeography of this area. Onshore, there are signs of neither Lower-Pliocene marine deposits nor Gilbert deltas. The absence of such sedimentary edifices, which are characteristic of the Pliocene refilling of the Mediterranean basin are clues about significant post-rift vertical movements in the Tyrrhenian sea.

Exploring co-investments in sustainable land management in the Central Rift Valley of Ethiopia

NARCIS (Netherlands)

Adimassu Teferi, Z.; Kessler, A.; Stroosnijder, L.

2013-01-01

In Ethiopia, not only farmers but also the public and private sector partners are still hesitant to invest in sustainable land management (SLM). This study focuses on the Central Rift Valley and explores the potential for co-investments in SLM, where public and private sector partners support

Rift Valley fever in Kenya: history of epizootics and identification of vulnerable districts.

Science.gov (United States)

Murithi, R M; Munyua, P; Ithondeka, P M; Macharia, J M; Hightower, A; Luman, E T; Breiman, R F; Njenga, M Kariuki

2011-03-01

Since Kenya first reported Rift Valley fever (RVF)-like disease in livestock in 1912, the country has reported the most frequent epizootics of RVF disease. To determine the pattern of disease spread across the country after its introduction in 1912, and to identify regions vulnerable to the periodic epizootics, annual livestock disease records at the Department of Veterinary Services from 1910 to 2007 were analysed in order to document the number and location of RVF-infected livestock herds. A total of 38/69 (55%) administrative districts in the country had reported RVF epizootics by the end of 2007. During the 1912-1950 period, the disease was confined to a district in Rift Valley province that is prone to flooding and where livestock were raised in proximity with wildlife. Between 1951 and 2007, 11 national RVF epizootics were recorded with an average inter-epizootic period of 3·6 years (range 1-7 years); in addition, all epizootics occurred in years when the average annual rainfall increased by more than 50% in the affected districts. Whereas the first two national epizootics in 1951 and 1955 were confined to eight districts in the Rift Valley province, there was a sustained epizootic between 1961 and 1964 that spread the virus to over 30% of the districts across six out of eight provinces. The Western and Nyanza provinces, located on the southwestern region of the country, had never reported RVF infections by 2007. The probability of a district being involved in a national epizootic was fivefold higher (62%) in districts that had previously reported disease compared to districts that had no prior disease activity (11%). These findings suggests that once introduced into certain permissive ecologies, the RVF virus becomes enzootic, making the region vulnerable to periodic epizootics that were probably precipitated by amplification of resident virus associated with heavy rainfall and flooding.

The persistence of rift valley fever in the Jazan region of Saudi Arabia.

Science.gov (United States)

Elfadil, A A; Hasab-Allah, K A; Dafa-Allah, O M; Elmanea, A A

2006-12-01

A survey was conducted in the Jazan region of Saudi Arabia to investigate the presence of Rift Valley fever (RVF) in sheep and goats, by clinical identification of suspected herds and detection of immunoglobulin M (IgM) antibodies to RVF virus. The level of herd immunity was identified by detecting immunoglobulin G (IgG) antibodies. Rift Valley fever was diagnosed in six out of eight districts included in the survey. Twenty-two animals from 17 herds tested positive for the presence of IgM antibodies against RVF in these districts. The infection rate ranged from 0.12% in the Sabya district to 1.04% in the Jizan district. The level of herd immunity ranged from 22.2% in Jizan to 39.3% in the Alarda district. It can be concluded that the presence of IgM antibodies in clinically suspected herds suggests persistent RVF infection in the Jazan region. Thus, RVF control programmes should be continued to prevent the recurrence of outbreaks in the region and the possible further spread of infection to other regions of Saudi Arabia.

Polyphased rifting to post-breakup evolution of the Coral Sea region, Papua New Guinea

Science.gov (United States)

Bulois, Cédric; Pubellier, Manuel; Chamot-Rooke, Nicolas; Delescluse, Matthias

2016-04-01

The Coral Sea Basin, offshore Papua New Guinea, is generally described as a rift propagator that opened through the Australian craton during the Late Cretaceous. Rifting was later followed by spreading activity during Palaeocene to lowermost Eocene times and basin inversion during the Cenozoic. Herein, we specifically describe the extensional structures and show that the area has actually a much longer history that dates back from the Late Palaeozoic. A special focus is made on the northern margin of the Coral Sea Basin along which subsurface and HD topographic data were recently acquired. Extension took place discontinuously from the Late Palaeozoic to the Lower Cenozoic through several rift megacycles that include extensional pulses and relaxation episodes. The first rift megacycle (R1), poorly documented, occurred during the Triassic along an old Permo-Triassic, NS-trending structural fabric. Evidence of Permo-Triassic features is principally observed in the western part of the Coral Sea near the Tasman Line, a major lithospheric discontinuity that marks the eastern limit of the underlying Australian craton in Papua New Guinea. This early Triassic framework was reactivated during a Jurassic rifting stage (R2), resulting in small (~10/20km) tilted basins bounded by major NS, NE-SW and EW normal faults. Extension formed a large basin, floored by oceanic crust that might have connected with the Tethys Ocean. The Owen Stanley Oceanic Basin containing deep-marine sediments now obducted in the Ocean Stanley Thrust Belt are likely to represent this oceanic terrane. Both R1 and R2 megacycles shaped the geometry of the Jurassic Australian margin. A third Cretaceous extensional megacycle (R3) only reactivated the largest faults, cutting through the midst of this early stretched continental margin. It formed wider, poorly tilted basins and terminated with the onset of the Coral Sea seafloor spreading from Danian to Ypresian times (61.8 to 53.4 Myr). Then, the overall

Esophageal cancer in north rift valley of Western Kenya.

Science.gov (United States)

Wakhisi, Johnston; Patel, Kritika; Buziba, Nathan; Rotich, Joseph

2005-06-01

Cancer of esophagus is the 9 th It is aggressive with poor prognosis especially in its late stage. Cancer of esophagus is geographically unevenly distributed with high incidence found within sharply demarcated geographic confines. Earlier reports from this country indicated relatively high proportion of cases in residents of Western and Central provinces with low incidence in the residents of the Rift Valley Province. This does not seem to be in agreement with our findings. Several aetiological factors have been associated with this type of cancer although their definitive mechanistic role is not clear. The main aim of this study was to describe the incidence, clinical epidemiology and histology of esophageal cancer in the North Rift region of Western Kenya, which forms the patients catchment area of Moi Teaching and Referral Hospital, Eldoret. This study involved a review of all available pathology reports beginning from January 1994 up to May 2001 from Moi Teaching and Referral Hospital. All reports of esophageal cancer were abstracted and analyzed according to gender, age and ethnical background. All cases were based on histological diagnosis. Statistical analysis was performed using the SPSS software package. Esophageal cancer in this area is the most common cancer in men, yet it is the third common cancer in women. A male to female ratio of 1.5 to 1 was observed. Our finding also contrast with an earlier reported study that indicated that Rift Valley is a low prevalence area for this type of cancer. The mean age of the patients with this cancer was 58.7 years. The ethnic group most afflicted were Nandis and Luhyas. They are the majority tribes in this area. Squamous cell carcinoma accounted for 90% of the cases. Cancer of the esophagus is the most common malignancy in males and the third common malignancy in females in the catchment area of Moi Teaching and Referral Hospital, Eldoret. There is need to carry out further work to establish the aetiologic factors

Red-Sea rift magmatism near Al Lith, Kingdom of Saudi Arabia

Science.gov (United States)

Pallister, J.S.

1986-01-01

A newly recognized Tertiary dike complex and comagmatic volcanic rocks exposed on the central Saudi Arabian coastal plain record early stages of magmatism related to Red Sea rifting. Intrusive and stratigraphic relationships, and new potassium-argon dating indicate episodic magmatism from about 30 Ma to the present. Additional stratigraphic and radiometric evidence suggests that limited rift-related magmatism may have began as early as about 50 Ma ago. An early phase of crustal extension in the region was accompanied by faulting and graben formation and by dike-swarm intrusion. The style of extension and intrusion changed approximately 20 Ma ago. Localized volcanism and sheeted dike injection ceased and were replaced by the intrusion of thick gabbro dikes. This change may mark the onset of sea-floor spreading in the central Red Sea.

Effect of environmental temperature on the vector competence of mosquitoes for Rift Valley fever virus

Science.gov (United States)

Environmental temperature has been shown to affect the ability of mosquitoes to transmit numerous arboviruses and for Rift Valley fever virus (RVFV) in particular. We evaluated the effect of incubation temperatures ranging from 14-26ºC on infection, dissemination, and transmission rates for Culex ta...

Temperature-sensitive mutations for live-attenuated Rift Valley fever vaccines: Implications from other RNA viruses

Directory of Open Access Journals (Sweden)

Shoko eNishiyama

2015-08-01

Full Text Available Rift Valley fever (RVF is a mosquito-borne zoonotic disease endemic to the African continent. RVF is characterized by high rate of abortions in ruminants and hemorrhagic fever, encephalitis or blindness in humans. RVF is caused by the Rift Valley fever virus (RVFV: genus Phlebovirus, family Bunyaviridae. Vaccination is the only known effective strategy to prevent the disease, but there are no licensed RVF vaccines available for humans. A live-attenuated vaccine candidate derived from the wild-type pathogenic Egyptian ZH548 strain, MP-12, has been conditionally licensed for veterinary use in the United States. MP-12 displays a temperature-sensitive (ts phenotype and does not replicate at 41oC. The ts mutation limits viral replication at a specific body temperature and may lead to an attenuation of the virus. Here we will review well-characterized ts mutations for RNA viruses, and further discuss the potential in designing novel live-attenuated vaccines for RVF.

The major tectonic boundaries of the Northern Red Sea rift, Egypt derived from geophysical data analysis

Science.gov (United States)

Saleh, Salah; Pamukçu, Oya; Brimich, Ladislav

2017-09-01

In the present study, we have attempted to map the plate boundary between Arabia and Africa at the Northern Red Sea rift region including the Suez rift, Gulf of Aqaba-Dead Sea transform and southeastern Mediterranean region by using gravity data analysis. In the boundary analysis method which was used; low-pass filtered gravity anomalies of the Northern Red Sea rift region were computed. Different crustal types and thicknesses, sediment thicknesses and different heat flow anomalies were evaluated. According to the results, there are six subzones (crustal blocks) separated from each other by tectonic plate boundaries and/or lineaments. It seems that these tectonic boundaries reveal complex structural lineaments, which are mostly influenced by a predominant set of NNW-SSE to NW-SE trending lineaments bordering the Red Sea and Suez rift regions. On the other side, the E-W and N-S to NNE-SSW trended lineaments bordering the South-eastern Mediterranean, Northern Sinai and Aqaba-Dead Sea transform regions, respectively. The analysis of the low pass filtered Bouguer anomaly maps reveals that the positive regional anomaly over both the Red Sea rift and South-eastern Mediterranean basin subzones are considered to be caused by the high density of the oceanic crust and/or the anomalous upper mantle structures beneath these regions whereas, the broad medium anomalies along the western half of Central Sinai with the Suez rift and the Eastern Desert subzones are attributed to low-density sediments of the Suez rift and/or the thick upper continental crustal thickness below these zones. There are observable negative anomalies over the Northern Arabia subzone, particularly in the areas covered by Cenozoic volcanics. These negative anomalies may be attributed to both the low densities of the surface volcanics and/or to a very thick upper continental crust. On the contrary, the negative anomaly which belongs to the Gulf of Aqaba-Dead Sea transform zone is due to crustal thickening

Yield gaps and resource use across farming zones in the central rift valley of Ethiopia

NARCIS (Netherlands)

Getnet, Mezegebu; Ittersum, van Martin; Hengsdijk, Huib; Descheemaeker, Katrien

2016-01-01

In the Central Rift Valley (CRV) of Ethiopia, low productive cereal systems and a declining resource base call for options to increase crop productivity and improve resource use efficiency to meet the growing demand of food. We compiled and analysed a large amount of data from farmers’ fields

The geochemistry of groundwater resources in the Jordan Valley: The impact of the Rift Valley brines

Science.gov (United States)

Farber, E.; Vengosh, A.; Gavrieli, I.; Marie, Amarisa; Bullen, T.D.; Mayer, B.; Polak, A.; Shavit, U.

2007-01-01

The chemical composition of groundwater in the Jordan Valley, along the section between the Sea of Galilee and the Dead Sea, is investigated in order to evaluate the origin of the groundwater resources and, in particular, to elucidate the role of deep brines on the chemical composition of the regional groundwater resources in the Jordan Valley. Samples were collected from shallow groundwater in research boreholes on two sites in the northern and southern parts of the Jordan Valley, adjacent to the Jordan River. Data is also compiled from previous published studies. Geochemical data (e.g., Br/Cl, Na/Cl and SO4/Cl ratios) and B, O, Sr and S isotopic compositions are used to define groundwater groups, to map their distribution in the Jordan valley, and to evaluate their origin. The combined geochemical tools enabled the delineation of three major sources of solutes that differentially affect the quality of groundwater in the Jordan Valley: (1) flow and mixing with hypersaline brines with high Br/Cl (>2 ?? 10-3) and low Na/Cl (shallow saline groundwaters influenced by brine mixing exhibit a north-south variation in their Br/Cl and Na/Cl ratios. This chemical trend was observed also in hypersaline brines in the Jordan valley, which suggests a local mixing process between the water bodies. ?? 2007 Elsevier Ltd. All rights reserved.

Restriction of Rift Valley Fever Virus Virulence in Mosquito Cells

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Sonja R. Gerrard

2010-02-01

Full Text Available Arboviruses are maintained in a natural cycle that requires blood-sucking arthropod and vertebrate hosts. Arboviruses are believed to persistently infect their arthropod host without overt pathology and cause acute infection with viremia in their vertebrate host. We have focused on elucidating how a specific arbovirus, Rift Valley fever (RVF virus, causes cytopathic effect in cells derived from vertebrates and non-cytopathic infection in cells derived from arthropods. We demonstrate that the vertebrate virulence factor, NSs, is functional in arthropod cells but is expressed at significantly lower levels in infected arthropod versus infected vertebrate cells.

Four-segmented Rift Valley fever virus-based vaccines can be applied safely in ewes during pregnancy

NARCIS (Netherlands)

Wichgers Schreur, Paul J.; Keulen, van Lucien; Kant-Eenbergen, Jet; Kortekaas, Jeroen

2017-01-01

Rift Valley fever virus (RVFV) causes severe and recurrent outbreaks on the African continent and the Arabian Peninsula and continues to expand its habitat. This mosquito-borne virus, belonging to the genus Phlebovirus of the family Bunyaviridae contains a tri-segmented negative-strand RNA

Rift-drift transition in the Dangerous Grounds, South China Sea

Science.gov (United States)

Peng, Xi; Shen, Chuanbo; Mei, Lianfu; Zhao, Zhigang; Xie, Xiaojun

2018-04-01

The South China Sea (SCS) has a long record of rifting before and after subsequent seafloor spreading, affecting the wide continent of the Dangerous Grounds, and its scissor-shape opening manner results in the rifting structures that vary along this margin. Some 2000 km of regional multichannel seismic data combined with borehole and dredge data are interpreted to analyze the multistage rifting process, structural architecture and dynamic evolution across the entire Dangerous Grounds. Key sequence boundaries above the Cenozoic basement are identified and classified into the breakup unconformity and the rift end unconformity, which consist of the rift-related unconformities. Reflector T70 in the east of the Dangerous Grounds represents the breakup unconformity, which is likely corresponding to the spreading of the East Subbasin. T60 formed on the top of carbonate platform is time equivalent to the spreading of the Southwest Subbasin, marking the breakup unconformity of the central Dangerous Grounds. The termination of the spreading of the SCS is manifested by the rift end unconformity of T50 in the southwest and the final rift occurring in the northwest of the Dangerous Grounds is postponed to the rift end unconformity of T40. On the basis of the stratigraphic and structural analysis, distinct segments in the structural architecture of the syn-rift units and the ages of rift-drift transition show obvious change from the proximal zone to the distal zone. Three domains, which are the Reed Bank-Palawan Rift domain, the Dangerous Grounds Central Detachment domain and Nam Con Son Exhumation domain, reflect the propagation of the margin rifting developed initially by grabens formed by high angle faults, then large half-grabens controlled by listric faults and detachments and finally rotated fault blocks in the hyper-extended upper crust associated with missing lower crust or exhumed mantle revealing a migration and stepwise rifting process in the south margin of the SCS.

Arabidopsis thaliana plants expressing Rift Valley fever virus antigens: Mice exhibit systemic immune responses as the result of oral administration of the transgenic plants.

Science.gov (United States)

Kalbina, Irina; Lagerqvist, Nina; Moiane, Bélisario; Ahlm, Clas; Andersson, Sören; Strid, Åke; Falk, Kerstin I

2016-11-01

The zoonotic Rift Valley fever virus affects livestock and humans in Africa and on the Arabian Peninsula. The economic impact of this pathogen due to livestock losses, as well as its relevance to public health, underscores the importance of developing effective and easily distributed vaccines. Vaccines that can be delivered orally are of particular interest. Here, we report the expression in transformed plants (Arabidopsis thaliana) of Rift Valley fever virus antigens. The antigens used in this study were the N protein and a deletion mutant of the Gn glycoprotein. Transformed lines were analysed for specific mRNA and protein content by RT-PCR and Western blotting, respectively. Furthermore, the plant-expressed antigens were evaluated for their immunogenicity in mice fed the transgenic plants. After oral intake of fresh transgenic plant material, a proportion of the mice elicited specific IgG antibody responses, as compared to the control animals that were fed wild-type plants and of which none sero-converted. Thus, we show that transgenic plants can be readily used to express and produce Rift Valley Fever virus proteins, and that the plants are immunogenic when given orally to mice. These are promising findings and provide a basis for further studies on edible plant vaccines against the Rift Valley fever virus. Copyright © 2016 Elsevier Inc. All rights reserved.

Potential for Mosquitoes (Diptera: Culicidae) From Florida to Transmit Rift Valley Fever Virus

Science.gov (United States)

2013-09-01

signiÞcant disease and economic disruption. Rift Valley fever virus (RVFV), whichhasbeen responsible fornumerousoutbreaksof severe disease in ruminants and...is predominately a disease of domestic ruminants (cattle, goats, and sheep), where infection in pregnant animals usually results in abortion, and...www.cdc.gov/EID/ content /13/8/e1.htm). Britch, S.C.,K. J.Linthicum,A.Anyamba,C. J.Tucker,E.W. Pak, F. A. Maloney, K. Cobb, E. Stanwix, J. Humphries, A

The modest seismicity of the northern Red Sea rift

Science.gov (United States)

Mitchell, Neil C.; Stewart, Ian C. F.

2018-05-01

Inferring tectonic movements from earthquakes (`seismotectonics') relies on earthquakes faithfully recording tectonic motions. In the northern half of the Red Sea, however, events of magnitude 5.0 and above are almost entirely absent from global catalogues, even though GPS and other plate motion data suggest that the basin is actively rifting at ˜10 mm yr-1. Seismic moments computed here from event magnitudes contributed to the International Seismology Centre (ISC) suggest that the moment release rate is more than an order of magnitude smaller than for the southern Red Sea and for the Southwest Indian Ridge (SWIR), which is spreading at a comparable rate to the central Red Sea and is more remote from recording stations. A smaller moment release rate in the northern Red Sea might be anticipated from its smaller spreading rate, but seismic coupling coefficients, which account for spreading rate variations, are also one order of magnitude smaller than for the other two areas. We explore potential explanations for this apparently reduced seismicity. The northern Red Sea is almost continuously covered with thick evaporites and overlying Plio-Pleistocene sediments. These deposits may have reduced the thickness of the seismogenic layer, for example, by elevating lithosphere temperatures by a thermal blanketing effect or by leading to excess pore fluid pressures that reduce effective stress. The presence of subdued seismicity here implies that tectonic movements can in places be poorly recorded by earthquake data and requires that alternative data be sought when investigating the active tectonics of sedimented rifts in particular.

Ecological niche modelling of Rift Valley fever virus vectors in Baringo, Kenya

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Alfred O. Ochieng

2016-11-01

Full Text Available Background: Rift Valley fever (RVF is a vector-borne zoonotic disease that has an impact on human health and animal productivity. Here, we explore the use of vector presence modelling to predict the distribution of RVF vector species under climate change scenario to demonstrate the potential for geographic spread of Rift Valley fever virus (RVFV. Objectives: To evaluate the effect of climate change on RVF vector distribution in Baringo County, Kenya, with an aim of developing a risk map for spatial prediction of RVF outbreaks. Methodology: The study used data on vector presence and ecological niche modelling (MaxEnt algorithm to predict the effect of climatic change on habitat suitability and the spatial distribution of RVF vectors in Baringo County. Data on species occurrence were obtained from longitudinal sampling of adult mosquitoes and larvae in the study area. We used present (2000 and future (2050 Bioclim climate databases to model the vector distribution. Results: Model results predicted potential suitable areas with high success rates for Culex quinquefasciatus, Culex univitattus, Mansonia africana, and Mansonia uniformis. Under the present climatic conditions, the lowlands were found to be highly suitable for all the species. Future climatic conditions indicate an increase in the spatial distribution of Cx. quinquefasciatus and M. africana. Model performance was statistically significant. Conclusion: Soil types, precipitation in the driest quarter, precipitation seasonality, and isothermality showed the highest predictive potential for the four species.

Identification of a major non-structural protein in the nuclei of Rift Valley fever virus-infected cells.

Science.gov (United States)

Struthers, J K; Swanepoel, R

1982-06-01

A non-structural protein of mol. wt. 34 X 10(3) was demonstrated in the nuclei of Rift Valley fever virus-infected Vero cells by SDS-polyacrylamide gel electro-phoresis. The protein appears to correspond to the virus-induced antigen demonstrated by indirect immunofluorescence in intranuclear inclusions.

Waves in the Red Sea: Response to monsoonal and mountain gap winds

KAUST Repository

Ralston, David K.; Jiang, Houshuo; Farrar, J. Thomas

2013-01-01

An unstructured grid, phase-averaged wave model forced with winds from a high resolution atmospheric model is used to evaluate wind wave conditions in the Red Sea over an approximately 2-year period. The Red Sea lies in a narrow rift valley

The Example of Eastern Africa: the dynamic of Rift Valley fever and tools for monitoring virus activity

Science.gov (United States)

Rift Valley fever is a mosquito-borne viral zoonosis that primarily affects animals but also has the capacity to infect humans. Outbreaks of this disease in eastern Africa are closely associated with periods of heavy rainfall and forecasting models and early warning systems have been developed to en...

Mapping of the mutations present in the genome of the Rift Valley fever virus attenuated MP12 strain and their putative role in attenuation.

Science.gov (United States)

Vialat, P; Muller, R; Vu, T H; Prehaud, C; Bouloy, M

1997-11-01

The MP12 attenuated strain of Rift Valley fever virus was obtained by 12 serial passages of a virulent isolate ZH548 in the presence of 5-fluorouracil (Caplen et al., 1985. Mutagen-directed attenuation of Rift Valley fever virus as a method for vaccine development. J. Gen. Virol., 66, 2271-2277). The comparison of the M segment of the two strains has already been reported by Takehara et al. (Takehara et al., 1989. Identification of mutations in the M RNA of a candidate vaccine strain of Rift Valley fever virus. Virology 169, 452-457). We have completed the comparison and found that altogether a total of nine, 12 and four nucleotides were changed in the L, M and S segments of the two strains, respectively. Three mutations induced amino acid changes in the L protein but none of them was located in the recognized motifs conserved among RNA dependent polymerases. In the S segment, a single change modified an amino acid in the NSs protein and in the M segment, seven of the mutations resulted in amino acid changes in each of the four encoded G1, G2, 14 kDa and 78 kDa proteins. Characterization of the MP12 virus indicated that determinants for attenuation were present in each segment and that they were introduced progressively during the 12 passages in the presence of the mutagen (Saluzzo and Smith, 1990. Use of reassortant viruses to map attenuating and temperature-sensitive mutations of the Rift Valley fever virus MP-12 vaccine. Vaccine 8, 369-375). Passages 4 and 7-9 were found to be essential for introduction of temperature-sensitive lesions and attenuation. In an attempt to correlate some of the mutations with the attenuated or temperature-sensitive phenotypes, we determined by sequencing the passage level at which the different mutations appeared. This work should help to address the question of the role of the viral gene products in Rift Valley fever pathogenesis.

Rift Valley fever virus NSs protein functions and the similarity to other bunyavirus NSs proteins.

Science.gov (United States)

Ly, Hoai J; Ikegami, Tetsuro

2016-07-02

Rift Valley fever is a mosquito-borne zoonotic disease that affects both ruminants and humans. The nonstructural (NS) protein, which is a major virulence factor for Rift Valley fever virus (RVFV), is encoded on the S-segment. Through the cullin 1-Skp1-Fbox E3 ligase complex, the NSs protein promotes the degradation of at least two host proteins, the TFIIH p62 and the PKR proteins. NSs protein bridges the Fbox protein with subsequent substrates, and facilitates the transfer of ubiquitin. The SAP30-YY1 complex also bridges the NSs protein with chromatin DNA, affecting cohesion and segregation of chromatin DNA as well as the activation of interferon-β promoter. The presence of NSs filaments in the nucleus induces DNA damage responses and causes cell-cycle arrest, p53 activation, and apoptosis. Despite the fact that NSs proteins have poor amino acid similarity among bunyaviruses, the strategy utilized to hijack host cells are similar. This review will provide and summarize an update of recent findings pertaining to the biological functions of the NSs protein of RVFV as well as the differences from those of other bunyaviruses.

A Novel System for Identification of Inhibitors of Rift Valley Fever Virus Replication

OpenAIRE

Piper, Mary E.; Gerrard, Sonja R.

2010-01-01

Rift Valley fever virus (RVFV) is a human and livestock pathogen endemic to sub-Saharan Africa. We have developed a T7-dependent system for the efficient production of RVFV-like particles (RVF-VLPs) based on the virulent ZH-501 strain of RVFV. The RVF-VLPs are capable of performing a single round of infection, allowing for the study of viral replication, assembly, and infectivity. We demonstrate that these RVF-VLPs are antigenically indistinguishable from authentic RVFV and respond similarly ...

Immunogenicity and efficacy of a chimpanzee adenovirus-vectored Rift Valley fever vaccine in mice.

OpenAIRE

Warimwe, GM; Lorenzo, G; Lopez-Gil, E; Reyes-Sandoval, A; Cottingham, MG; Spencer, AJ; Collins, KA; Dicks, MD; Milicic, A; Lall, A; Furze, J; Turner, AV; Hill, AV; Brun, A; Gilbert, SC

2013-01-01

BACKGROUND: Rift Valley Fever (RVF) is a viral zoonosis that historically affects livestock production and human health in sub-Saharan Africa, though epizootics have also occurred in the Arabian Peninsula. Whilst an effective live-attenuated vaccine is available for livestock, there is currently no licensed human RVF vaccine. Replication-deficient chimpanzee adenovirus (ChAd) vectors are an ideal platform for development of a human RVF vaccine, given the low prevalence of neutralizing antibod...

Crop intensification options and trade-offs with the water balance in the Central Rift Valley of Ethiopia

NARCIS (Netherlands)

Debas, Mezegebu

2016-01-01

The Central Rift Valley (CRV) of Ethiopia is a closed basin for which claims on land and water have strongly increased over the past decade resulting in over-exploitation of the resources. A clear symptom is the declining trend in the water level of the terminal Lake Abyata. The actual

Interventions Against West Nile Virus, Rift Valley Fever Virus, and Crimean-Congo Hemorrhagic Fever Virus: Where Are We?

NARCIS (Netherlands)

Kortekaas, J.A.; Ergonul, O.; Moormann, R.J.M.

2010-01-01

ARBO-ZOONET is an international network financed by the European Commission's seventh framework program. The major goal of this initiative is capacity building for the control of emerging viral vector-borne zoonotic diseases, with a clear focus on West Nile virus, Rift Valley fever virus, and

Neotectonics of the Roer Valley rift system; style and rate of crustal deformation inferred from syn-tectonic sedimentation

NARCIS (Netherlands)

Berg, van den M.W.

1995-01-01

River sediments of the Meuse, Rhine and local Belgian systems have been preserved in various parts of the Roer Valley rift. Age-altitude positions of Meuse terraces provide a detailed record of neotectonic regional uplift. It shows accelerations and decelerations superimposed on a long-term average

Comparison of hydrothermal activity between the Adriatic and the Red Sea rift margins

Science.gov (United States)

Ball, Philip; Incerpi, Nicolò; Birkle, Peter; Lacsamana, Elizabeth; Manatschal, Gianreto; Agar, Susan; Zhang, Shuo; Borsato, Ron

2017-04-01

Detailed field studies, and access to high-quality seismic reflection and refraction data have led to an improved understanding of the architecture and evolution of magma poor and magma rich margins. Associated with the spatial-temporal evolution of the rift, it is evident that there are evolving, extensive, fluid-rock interactions due to the infiltration of fluids within the sediment, basement and lithospheric mantle. Key questions therefore arise: What are the different fluid-rock reactions that can be typed to different geodynamic stages of the rift evolution? What are their compositions and how do they interact with their environment (basement, sediments, evaporites, hydrosphere, and magmatism)? What are the implications for the evolution of the margin rheology, thermal structure, depositional environments/organic matter maturity, and reservoir quality? The Adriatic paleo-rifted margin is preserved in both SE Switzerland and northern Italy. The field exposures provide a unique opportunity to study the fluid flow history of a hyperextended magma poor extensional margin. Analysis of breccias, cement veins and replacement minerals reveal that the margin records a complex, long-lasting history of dolomitization, calcification and silicification during the Jurassic rifting. The Red Sea by contrast is a young rifted margin. It differs from the paleo-Adriatic margin by several characteristics: volcanism is more evident, and syn-tectonic sediments, including evaporites (halite and anhydrite) are thicker. Several core and fluid samples are available from both onshore and offshore wells, which reveal rift-related hydrothermal alteration. In addition, we find evidence for the presence of an extreme dynamic hydraulic system with infiltration of surface water into sub-salt units during Late Pleistocene. In this study we present results from petrographic and geochemical analysis of basement and sedimentary rocks from Adriatic field-derived samples and core/subsurface fluid

Rift Valley fever virus NS{sub S} gene expression correlates with a defect in nuclear mRNA export

Energy Technology Data Exchange (ETDEWEB)

Copeland, Anna Maria; Van Deusen, Nicole M.; Schmaljohn, Connie S., E-mail: Connie.s.schmaljohn.civ@mail.mil

2015-12-15

We investigated the localization of host mRNA during Rift Valley fever virus (RVFV) infection. Fluorescence in situ hybridization revealed that infection with RVFV altered the localization of host mRNA. mRNA accumulated in the nuclei of RVFV-infected but not mock-infected cells. Further, overexpression of the NS{sub S} gene, but not the N, G{sub N} or NS{sub M} genes correlated with mRNA nuclear accumulation. Nuclear accumulation of host mRNA was not observed in cells infected with a strain of RVFV lacking the gene encoding NS{sub S}, confirming that expression of NS{sub S} is likely responsible for this phenomenon. - Highlights: • Rift Valley fever virus (RVFV) infection alters the localization of host mRNA. • mRNA accumulates in the nuclei of RVFV-infected but not mock-infected cells. • NS{sub S} is likely responsible for mRNA relocalization to the nucleus.

Monitoring of the Syrian rift valley using radon measurement technique in groundwater

International Nuclear Information System (INIS)

Jubeli, Y.; Al-Ali, M.A.; Al-Hilall, M.

1999-07-01

Radon concentrations in groundwater were measured from six monitoring stations that were distributed along the Syrian rift valley, with time intervals of one month over a span of more than six years from 1992 to 1998. This set of data was integrated and statistically handled in order to be used as a significant base for estimating the range of natural radon background variations in groundwater along the concerned zone. The results reveal that only few anomalous radon values were recorded during the given time-window, which might be caused by tectonic disturbances or otherwise in the study region. (author)

Spatial and Temporal Strain Distribution Along the Central Red Sea Rift - A Study of the Hamd-Jizil Basin in Saudi Arabia

Science.gov (United States)

Szymanski, E.; Stockli, D.; Johnson, P.; Kattan, F. H.; Al Shamari, A.

2006-12-01

Numerous models exploring the rupturing modes and mechanisms of continental lithosphere are based on geological evidence from the Red Sea/Gulf of Suez rift system. Individually, the Red Sea basin is the prototype for many models of orthogonal continental rifting. Despite being a classic example of continental extension, many temporal and spatial strain distribution aspects, as well as the dynamic evolution of the rift architecture of the Red Sea, remain poorly constrained. Critical data come mostly from the Gulf of Suez and the Egyptian and Yemeni margins of the Red Sea; the rift flanks in Sudan and Saudi Arabia have remained largely unstudied, leaving a large information gap along the central portions of the rift system. Improving continental lithosphere rupture models requires an absolute understanding of the timing and magnitude of strain partitioning along the full rift flank. This study focuses on the development of extensional structures, syn- extensional sedimentary deposits, and rift-related Tertiary basaltic volcanism along the central flank of the rift system in Saudi Arabia. Geo- and thermochronometric techniques are used to elucidate the evolution of inboard and outboard strain markers manifested by structurally-controlled extensional basins that parallel the trend of the main Red Sea rift. Constraints on the dynamics of rift flank deformation are achieved through the collection of thermochronometric transects that traverse both the entire Arabian shield and individual normal faults that bound inland basins. Preliminary results show inland basins as asymmetric half-grabens filled by tilted Cenozoic sedimentary strata and separated by exhumed basement fault blocks. The most prominent extensional basin is the NW-trending Hamd-Jizil basin, located north of Madinah, measuring ~200 km along strike and up to 20 km in width. The Hamd-Jizil basin is structurally characterized by two half-grabens exposing a series of syn-rift siliciclastic sedimentary sections

Large mammals from the Upper Neopleistocene reference sections in the Tunka rift valley, southwestern Baikal Region

Science.gov (United States)

Shchetnikov, A. A.; Klementiev, A. M.; Filinov, I. A.; Semeney, E. Yu.

2015-03-01

This work presents the data on new finds of fossil macrotheriofauna in the reference sections of the Upper Neopleistocene sediments in the Tunka rift valley (southwestern Baikal Region). The osteological material of a number of Late Neopleistocene mammals including extinct species rare for the Baikal region such as Crocuta spelaea, Panthera spelaea, and Spirocerus kiakhtensis (?) was directly dated with a radiocarbon (AMS) method. The obtained 14C data (18000-35000 years) allow one to rejuvenate significantly the upper limit of the common age interval of habitat of these animals in southern part of Eastern Siberia. Cave hyena and spiral-horned antelope lived in the Tunka rift valley in the Baikal region in Late Kargino time (37-24 ka), and cave lion survived the maximum in the Sartan cryochron in the region (21-20 ka). The study of collected paleontological collections provides a basis for selection of independent Kargino (MIS 3) faunal assemblages to use them for regional biostratigraphic analysis of Pleistocene deposits. Radiocarbon age dating of samples allows one to attribute confidently all paleofaunal remains available to the second half of the Late Pleistocene.

Assessment and recommendations for two sites with active and potential aquaculture production in Rift Valley and Coast Provinces, Kenya

Science.gov (United States)

Kenya has a long history of local fish consumption. The population in the Lake Victoria area (Rift Valley Province) Northwest of Nairobi and coastal communities (Coast Province) have historically included fish in their diet. Migration from villages to urban areas and increasing commerce has created ...

Single-particle cryo-electron microscopy of Rift Valley fever virus

International Nuclear Information System (INIS)

Sherman, Michael B.; Freiberg, Alexander N.; Holbrook, Michael R.; Watowich, Stanley J.

2009-01-01

Rift Valley fever virus (RVFV; Bunyaviridae; Phlebovirus) is an emerging human and veterinary pathogen causing acute hepatitis in ruminants and has the potential to cause hemorrhagic fever in humans. We report a three-dimensional reconstruction of RVFV vaccine strain MP-12 (RVFV MP-12) by cryo-electron microcopy using icosahedral symmetry of individual virions. Although the genomic core of RVFV MP-12 is apparently poorly ordered, the glycoproteins on the virus surface are highly symmetric and arranged on a T = 12 icosahedral lattice. Our RVFV MP-12 structure allowed clear identification of inter-capsomer contacts and definition of possible glycoprotein arrangements within capsomers. This structure provides a detailed model for phleboviruses, opens new avenues for high-resolution structural studies of the bunyavirus family, and aids the design of antiviral diagnostics and effective subunit vaccines.

Single-particle cryo-electron microscopy of Rift Valley fever virus.

Science.gov (United States)

Sherman, Michael B; Freiberg, Alexander N; Holbrook, Michael R; Watowich, Stanley J

2009-04-25

Rift Valley fever virus (RVFV; Bunyaviridae; Phlebovirus) is an emerging human and veterinary pathogen causing acute hepatitis in ruminants and has the potential to cause hemorrhagic fever in humans. We report a three-dimensional reconstruction of RVFV vaccine strain MP-12 (RVFV MP-12) by cryo-electron microcopy using icosahedral symmetry of individual virions. Although the genomic core of RVFV MP-12 is apparently poorly ordered, the glycoproteins on the virus surface are highly symmetric and arranged on a T=12 icosahedral lattice. Our RVFV MP-12 structure allowed clear identification of inter-capsomer contacts and definition of possible glycoprotein arrangements within capsomers. This structure provides a detailed model for phleboviruses, opens new avenues for high-resolution structural studies of the bunyavirus family, and aids the design of antiviral diagnostics and effective subunit vaccines.

Post-rift magmatism in the Pearl River Mouth Basin, northern South China Sea

Science.gov (United States)

Xu, H.; Zhao, F.; Xia, S.; Sun, J.; Fan, C.

2017-12-01

Multi-beam, 2D seismic reflection and borehole data reveal that post-rift magmatism are widespread in the northern margin of South China Sea. A large-scale volcanic complex was identified at water depths of 500 to 3000 m, covering an area of ca. 8000 km2. This volcanic complex includes seamounts, igneous sills, dykes and intruded volcanic bodies. Combining data from exploration wells BY7-1 and BY2 with published seismic stratigraphic data, we can highlight multiple extrusive events from the Early Oligocene to Early Miocene, reflecting progressive continental breakup in the South China Sea. Most intruded magma through the continental crust also uplifted sediments up to the T6 unconformity. Given the evidence in this work that Early Miocene magmatic bodies were developed above or along faults, we suggest that post-rift magmatism in the northern margin of the South China Sea was largely controlled by the faults. Reactivation events in the faults are suggested to have generated preferential vertical pathways for the ascent of magma within a context of progressive continental breakup and thinned continental crust, as the South China Sea was being formed.

Surveillance of Rift Valley Fever in Iran between 2001 and 2011

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Sadegh CHINIKAR

2013-06-01

Full Text Available Rift Valley fever virus (RVFV is an acute zoonotic viral disease that mostly affects ruminants with an occasional spillover as human infection. Following the outbreak of RVF in Saudi Arabia in 2000, surveillance of both animal and human population in Iran increased until 2011. During this period 1206 ovine, 405 caprine, 325 bovine and 28 camel samples were tested for RVFV in nine provinces in Iran. None of these samples tested IgG positive. Moreover, amongst 37 clinically suspected human cases of patients with RVF symptoms, none of these samples tested positive for RVFV. Despite the fact that no positive cases in human or animal populations were identified in Iran, surveillance and monitoring of viral haemorrhagic fevers including RVFV will continue.

Surveillance of Rift Valley Fever in Iran between 2001 and 2011

Directory of Open Access Journals (Sweden)

Sadegh CHINIKAR

2013-04-01

Full Text Available Rift Valley fever virus (RVFV is an acute zoonotic viral disease that mostly affects ruminants with an occasional spillover as human infection. Following the outbreak of RVF in Saudi Arabia in 2000, surveillance of both animal and human population in Iran increased until 2011. During this period 1206 ovine, 405 caprine, 325 bovine and 28 camel samples were tested for RVFV in nine provinces in Iran. None of these samples tested IgG positive. Moreover, amongst 37 clinically suspected human cases of patients with RVF symptoms, none of these samples tested positive for RVFV. Despite the fact that no positive cases in human or animal populations were identified in Iran, surveillance and monitoring of viral haemorrhagic fevers including RVFV will continue.

Efficient cellular release of Rift Valley fever virus requires genomic RNA.

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Mary E Piper

2011-03-01

Full Text Available The Rift Valley fever virus is responsible for periodic, explosive epizootics throughout sub-Saharan Africa. The development of therapeutics targeting this virus is difficult due to a limited understanding of the viral replicative cycle. Utilizing a virus-like particle system, we have established roles for each of the viral structural components in assembly, release, and virus infectivity. The envelope glycoprotein, Gn, was discovered to be necessary and sufficient for packaging of the genome, nucleocapsid protein and the RNA-dependent RNA polymerase into virus particles. Additionally, packaging of the genome was found to be necessary for the efficient release of particles, revealing a novel mechanism for the efficient generation of infectious virus. Our results identify possible conserved targets for development of anti-phlebovirus therapies.

Monitoring of the Syrian rift valley using radon technique

International Nuclear Information System (INIS)

Al-Hilal, M.; Al-Ali, A.; Jubeli, Y.

1997-02-01

Groundwater radon data were recorded once every two months from six monitoring sites of the Syrian rift valley during the year 1996. Radon samples were measured from deep artesian wells and from continuously-flowing springs that are distributed along this most active seismic zone in Syria. The available data were integrated with previously measured groundwater radon data from the same stations in order to estimate the range of normal radon fluctuations in the region. The estimation of such range may enable the separation between usual groundwater radon variations from other outliers which may indicate possible tectonic activities or earthquake hazards in the study area. Periodical radon measurements based on two months intervals and long distance between sampling stations does not enable us to trust with high level of confidence the connection between radon values and any possible earth dynamics. Therefore, shorter measuring time with closer monitoring sites are highly recommended to achieve the optimum advantage of such application. (Author). 8 Figs., 2 Tabs., 10 Refs

Rift Valley Fever Outbreaks in Mauritania and Related Environmental Conditions

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Cyril Caminade

2014-01-01

Full Text Available Four large outbreaks of Rift Valley Fever (RVF occurred in Mauritania in 1998, 2003, 2010 and 2012 which caused lots of animal and several human deaths. We investigated rainfall and vegetation conditions that might have impacted on RVF transmission over the affected regions. Our results corroborate that RVF transmission generally occurs during the months of September and October in Mauritania, similarly to Senegal. The four outbreaks were preceded by a rainless period lasting at least a week followed by heavy precipitation that took place during the second half of the rainy season. First human infections were generally reported three to five weeks later. By bridging the gap between meteorological forecasting centers and veterinary services, an early warning system might be developed in Senegal and Mauritania to warn decision makers and health services about the upcoming RVF risk.

Rift Valley fever virus MP-12 vaccine encoding Toscana virus NSs retains neuroinvasiveness in mice.

Science.gov (United States)

Indran, Sabarish V; Lihoradova, Olga A; Phoenix, Inaia; Lokugamage, Nandadeva; Kalveram, Birte; Head, Jennifer A; Tigabu, Bersabeh; Smith, Jennifer K; Zhang, Lihong; Juelich, Terry L; Gong, Bin; Freiberg, Alexander N; Ikegami, Tetsuro

2013-07-01

Rift Valley fever is a mosquito-borne zoonotic disease endemic to sub-Saharan Africa. Rift Valley fever virus (RVFV; genus Phlebovirus, family Bunyaviridae) causes high rates of abortion and fetal malformation in pregnant ruminants, and haemorrhagic fever, neurological disorders or blindness in humans. The MP-12 strain is a highly efficacious and safe live-attenuated vaccine candidate for both humans and ruminants. However, MP-12 lacks a marker to differentiate infected from vaccinated animals. In this study, we originally aimed to characterize the efficacy of a recombinant RVFV MP-12 strain encoding Toscana virus (TOSV) NSs gene in place of MP-12 NSs (rMP12-TOSNSs). TOSV NSs promotes the degradation of dsRNA-dependent protein kinase (PKR) and inhibits interferon-β gene up-regulation without suppressing host general transcription. Unexpectedly, rMP12-TOSNSs increased death in vaccinated outbred mice and inbred BALB/c or C57BL/6 mice. Immunohistochemistry showed diffusely positive viral antigens in the thalamus, hypothalamus and brainstem, including the medulla. No viral antigens were detected in spleen or liver, which is similar to the antigen distribution of moribund mice infected with MP-12. These results suggest that rMP12-TOSNSs retains neuroinvasiveness in mice. Our findings demonstrate that rMP12-TOSNSs causes neuroinvasion without any hepatic disease and will be useful for studying the neuroinvasion mechanism of RVFV and TOSV.

Load structure seismites in the Dead Sea Area, Israel : Chronological benchmarking with C-14 dating

NARCIS (Netherlands)

Bowman, D; Bruins, HJ; van der Plicht, J; Boaretto, E.; Bruins, Hendrik J.; Carmi, I.

2001-01-01

The Dead Sea is a terminal lake located in the seismically active zone of the Syro-African Rift Valley. The water level of the Dead Sea has been receding dramatically during the last decades, resulting in significant entrenchment of wadis towards its shores. Exposed sections in fan deltas reveal

Prediction, assessment of the Rift Valley fever activity in East and Southern Africa 2006-2008 and possible vector control strategies.

Science.gov (United States)

Anyamba, Assaf; Linthicum, Kenneth J; Small, Jennifer; Britch, Seth C; Pak, Edwin; de La Rocque, Stephane; Formenty, Pierre; Hightower, Allen W; Breiman, Robert F; Chretien, Jean-Paul; Tucker, Compton J; Schnabel, David; Sang, Rosemary; Haagsma, Karl; Latham, Mark; Lewandowski, Henry B; Magdi, Salih Osman; Mohamed, Mohamed Ally; Nguku, Patrick M; Reynes, Jean-Marc; Swanepoel, Robert

2010-08-01

Historical outbreaks of Rift Valley fever (RVF) since the early 1950s have been associated with cyclical patterns of the El Niño/Southern Oscillation (ENSO) phenomenon, which results in elevated and widespread rainfall over the RVF endemic areas of Africa. Using satellite measurements of global and regional elevated sea surface temperatures, elevated rainfall, and satellite derived-normalized difference vegetation index data, we predicted with lead times of 2-4 months areas where outbreaks of RVF in humans and animals were expected and occurred in the Horn of Africa, Sudan, and Southern Africa at different time periods from September 2006 to March 2008. Predictions were confirmed by entomological field investigations of virus activity and by reported cases of RVF in human and livestock populations. This represents the first series of prospective predictions of RVF outbreaks and provides a baseline for improved early warning, control, response planning, and mitigation into the future.

Numerical modelling of edge-driven convection during rift-to-drift transition: application to the Red Sea

Science.gov (United States)

Fierro, Elisa; Capitanio, Fabio A.; Schettino, Antonio; Morena Salerno, V.

2017-04-01

We use numerical modeling to investigate the coupling of mantle instabilities and surface tectonics along lithospheric steps developing during rifting. We address whether edge driven convection (EDC) beneath rifted continental margins and shear flow during rift-drift transition can play a role in the observed post-rift compressive tectonic evolution of the divergent continental margins along the Red Sea. We run a series of 2D simulations to examine the relationship between the maximum compression and key geometrical parameters of the step beneath continental margins, such as the step height due to lithosphere thickness variation and the width of the margins, and test the effect of rheology varying temperature- and stress-dependent viscosity in the lithosphere and asthenosphere. The development of instabilities is initially illustrated as a function of these parameters, to show the controls on the lithosphere strain distribution and magnitude. We then address the transient evolution of the instabilities to characterize their duration. In an additional suite of models, we address the development of EDC during plate motions, thus accounting for the mantle shearing due to spreading. Our results show an increase of strain with the step height as well as with the margin width up to 200 km. After this value the influence of ridge margin can be neglected. Strain rates are, then, quantified for a range of laboratory-constrained constitutive laws for mantle and lithosphere forming minerals. These models propose a viable mechanism to explain the post-rift tectonic inversion observed along the Arabian continental margin and the episodic ultra-fast sea floor spreading in the central Red Sea, where the role of EDC has been invoked.

A Novel System for Identification of Inhibitors of Rift Valley Fever Virus Replication

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Mary E. Piper

2010-03-01

Full Text Available Rift Valley fever virus (RVFV is a human and livestock pathogen endemic to sub-Saharan Africa. We have developed a T7-dependent system for the efficient production of RVFV-like particles (RVF-VLPs based on the virulent ZH-501 strain of RVFV. The RVF-VLPs are capable of performing a single round of infection, allowing for the study of viral replication, assembly, and infectivity. We demonstrate that these RVF-VLPs are antigenically indistinguishable from authentic RVFV and respond similarly to a wide array of known and previously unknown chemical inhibitors. This system should be useful for screening for small molecule inhibitors of RVFV replication.

A novel system for identification of inhibitors of rift valley Fever virus replication.

Science.gov (United States)

Piper, Mary E; Gerrard, Sonja R

2010-03-01

Rift Valley fever virus (RVFV) is a human and livestock pathogen endemic to sub-Saharan Africa. We have developed a T7-dependent system for the efficient production of RVFV-like particles (RVF-VLPs) based on the virulent ZH-501 strain of RVFV. The RVF-VLPs are capable of performing a single round of infection, allowing for the study of viral replication, assembly, and infectivity. We demonstrate that these RVF-VLPs are antigenically indistinguishable from authentic RVFV and respond similarly to a wide array of known and previously unknown chemical inhibitors. This system should be useful for screening for small molecule inhibitors of RVFV replication.

Hydrothermal circulation, serpentinization, and degassing at a rift valley-fracture zone intersection: Mid-Atlantic Ridge near 15[degree]N, 45[degree]W

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Rona, P.A.; Nelson, T.A. (National Oceanic and Atmospheric Administration, Miami, FL (United States)); Bougault, H.; Charlou, J.L.; Needham, H.D. (Inst. Francais de Recherche pour I' Exploitation de la Mer, Centre de Brest (France)); Appriou, P. (Univ. of Western Brittany, Brest (France)); Trefry, J.H. (Florida Inst. of Technology, Melbourne (United States)); Eberhart, G.L.; Barone, A. (Lamont-Doherty Geological Observatory, Palisades, NY (United States))

1992-09-01

A hydrothermal system characterized by high ratios of methane to both manganese and suspended particulate matter was detected in seawater sampled at the eastern intersection of the rift valley of the Mid-Atlantic Ridge with the Fifteen-Twenty Fracture Zone. This finding contrasts with low ratios in black smoker-type hydrothermal systems that occur within spreading segments. Near-bottom water sampling coordinated with SeaBeam bathymetry and camera-temperature tows detected the highest concentrations of methane at fault zones in rocks with the appearance of altered ultramafic units in a large dome that forms part of the inside corner high at the intersection. The distinct chemical signatures of the two types of hydrothermal systems are inferred to be controlled by different circulation pathways related to reaction of seawater primarily with ultramafic rocks at intersections of spreading segments with fracture zones but with mafic rocks within spreading segments.

Farmers' Perceptions of Land Degradation and their Investments in Land Management: a Case Study in the Cental Rift Valley of Ethiopia

NARCIS (Netherlands)

Adimassu, Zenebe; Kessler, A.; Yirga, C.

2013-01-01

To combat land degradation in the Central Rift Valley (CRV) of Ethiopia, farmers are of crucial importance. If farmers perceive land degradation as a problem, the chance that they invest in land management measures will be enhanced. This study presents farmers’ perceptions of land degradation and

A dynamic, climate-driven model of Rift Valley fever

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Joseph Leedale

2016-03-01

Full Text Available Outbreaks of Rift Valley fever (RVF in eastern Africa have previously occurred following specific rainfall dynamics and flooding events that appear to support the emergence of large numbers of mosquito vectors. As such, transmission of the virus is considered to be sensitive to environmental conditions and therefore changes in climate can impact the spatiotemporal dynamics of epizootic vulnerability. Epidemiological information describing the methods and parameters of RVF transmission and its dependence on climatic factors are used to develop a new spatio-temporal mathematical model that simulates these dynamics and can predict the impact of changes in climate. The Liverpool RVF (LRVF model is a new dynamic, process-based model driven by climate data that provides a predictive output of geographical changes in RVF outbreak susceptibility as a result of the climate and local livestock immunity. This description of the multi-disciplinary process of model development is accessible to mathematicians, epidemiological modellers and climate scientists, uniting dynamic mathematical modelling, empirical parameterisation and state-of-the-art climate information.

Infilling and flooding of the Mekong River incised valley during deglacial sea-level rise

Science.gov (United States)

Tjallingii, Rik; Stattegger, Karl; Wetzel, Andreas; Van Phach, Phung

2010-06-01

The abrupt transition from fluvial to marine deposition of incised-valley-fill sediments retrieved from the southeast Vietnamese shelf, accurately records the postglacial transgression after 14 ka before present (BP). Valley-filling sediments consist of fluvial mud, whereas sedimentation after the transgression is characterized by shallow-marine carbonate sands. This change in sediment composition is accurately marked in high-resolution X-ray fluorescence (XRF) core scanning records. Rapid aggradation of fluvial sediments at the river mouth nearly completely filled the Mekong incised valley prior to flooding. However, accumulation rates strongly reduced in the valley after the river-mouth system flooded and stepped back. This also affected the sediment supply to deeper parts of the southeast Vietnamese shelf. Comparison of the Mekong valley-filling with the East Asian sea-level history of sub- and inter-tidal sediment records shows that the transgressive surface preserved in the incised-valley-fill records is a robust sea-level indicator. The valley was nearly completely filled with fluvial sediments between 13.0 and 9.5 ka BP when sea-level rose rather constantly with approximately 10 mm/yr, as indicated by the East Asian sea-level record. At shallower parts of the shelf, significant sediment reworking and the establishment of estuarine conditions at the final stage of infilling complicates accurate dating of the transgressive surface. Nevertheless, incised-valley-fill records and land-based drill sites indicate a vast and rapid flooding of the shelf from the location of the modern Vietnamese coastline to the Cambodian lowlands between 9.5 ka and 8.5 ka BP. Fast flooding of this part of the shelf is related with the low shelf gradient and a strong acceleration of the East Asian sea-level rise from 34 to 9 meter below modern sea level (mbsl) corresponding to the sea-level jump of melt water pulse (MWP) 1C.

Continentward-dipping detachment fault system and asymmetric rift structure of the Baiyun Sag, northern South China Sea

Science.gov (United States)

Zhou, Zhichao; Mei, Lianfu; Liu, Jun; Zheng, Jinyun; Chen, Liang; Hao, Shihao

2018-02-01

The rift architecture and deep crustal structure of the distal margin at the mid-northern margin of the South China Sea have been previously investigated by using deep seismic reflection profiles. However, one fundamental recurring problem in the debate is the extensional fault system and rift structure of the hyperextended rift basins (Baiyun Sag and Liwan Sag) within the distal margin because of the limited amount of seismic data. Based on new 3D seismic survey data and 2D seismic reflection profiles, we observe an array of fault blocks in the Baiyun Sag, which were tilted towards the ocean by extensional faulting. The extensional faults consistently dip towards the continent. Beneath the tilted fault blocks and extensional faults, a low-angle, high-amplitude and continuous reflection has been interpreted as the master detachment surface that controls the extension process. During rifting, the continentward-dipping normal faults evolved in a sequence from south to north, generating the asymmetric rift structure of the Baiyun Sag. The Baiyun Sag is separated from the oceanic domain by a series of structural highs that were uplifted by magmatic activity in response to the continental breakup at 33 Ma and a ridge jump to the south at 26-24 Ma. Therefore, we propose that magmatism played a significant role in the continental extension and final breakup in the South China Sea.

Identification of Rift Valley Fever Virus Nucleocapsid Protein-RNA Binding Inhibitors Using a High-Throughput Screening Assay

OpenAIRE

Ellenbecker, Mary; Lanchy, Jean-Marc; Lodmell, J. Stephen

2012-01-01

Rift Valley fever virus (RVFV) is an emerging infectious pathogen that causes severe disease in humans and livestock and has the potential for global spread. Currently, there is no proven effective treatment for RVFV infection and there is no licensed vaccine. Inhibition of RNA binding to the essential viral nucleocapsid (N) protein represents a potential anti-viral therapeutic strategy because all of the functions performed by N during infection involve RNA binding. To target this interactio...

A network-based meta-population approach to model Rift Valley fever epidemics.

Science.gov (United States)

Xue, Ling; Scott, H Morgan; Cohnstaedt, Lee W; Scoglio, Caterina

2012-08-07

Rift Valley fever virus (RVFV) has been expanding its geographical distribution with important implications for both human and animal health. The emergence of Rift Valley fever (RVF) in the Middle East, and its continuing presence in many areas of Africa, has negatively impacted both medical and veterinary infrastructures and human morbidity, mortality, and economic endpoints. Furthermore, worldwide attention should be directed towards the broader infection dynamics of RVFV, because suitable host, vector and environmental conditions for additional epidemics likely exist on other continents; including Asia, Europe and the Americas. We propose a new compartmentalized model of RVF and the related ordinary differential equations to assess disease spread in both time and space; with the latter driven as a function of contact networks. Humans and livestock hosts and two species of vector mosquitoes are included in the model. The model is based on weighted contact networks, where nodes of the networks represent geographical regions and the weights represent the level of contact between regional pairings for each set of species. The inclusion of human, animal, and vector movements among regions is new to RVF modeling. The movement of the infected individuals is not only treated as a possibility, but also an actuality that can be incorporated into the model. We have tested, calibrated, and evaluated the model using data from the recent 2010 RVF outbreak in South Africa as a case study; mapping the epidemic spread within and among three South African provinces. An extensive set of simulation results shows the potential of the proposed approach for accurately modeling the RVF spreading process in additional regions of the world. The benefits of the proposed model are twofold: not only can the model differentiate the maximum number of infected individuals among different provinces, but also it can reproduce the different starting times of the outbreak in multiple locations

Common host-derived chemicals increase catches of disease-transmitting mosquitoes and can improve early warning systems for rift valley fever virus

Science.gov (United States)

Rift Valley fever (RVF), a mosquito-borne zoonosis, is a major public health problem in sub-Saharan Africa. The emergence and re-emergence of the disease in the last 20 years especially in East Africa, poses a looming health threat which is likely to spread to beyond Africa. This threat is exacerbat...

Impact of Global Climate on Rift Valley Fever and other Vector-borne Disease Outbreaks

Science.gov (United States)

Linthicum, K. J.

2017-12-01

Rift Valley fever is a viral disease of animals and humans in Africa and the Middle East that is transmitted by mosquitoes. Since the virus was first isolated in Kenya in 1930 it has caused significant impact to animal and human health and national economies, and it is of concern to the international agricultural and public health community. In this presentation we will describe the (1) ecology of disease transmission as it relates to climate, (2) the impact of climate and other environmental conditions on outbreaks, (3) the ability to use global climate information to predict outbreaks, (4) effective response activities, and (4) the potential to mitigate globalization.

Rift Valley fever virus seroprevalence in human rural populations of Gabon.

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Xavier Pourrut

Full Text Available BACKGROUND: Rift Valley fever (RVF is a mosquito-borne viral zoonosis caused by a phlebovirus and transmitted by Aedes mosquitoes. Humans can also be infected through direct contact with blood (aerosols or tissues (placenta, stillborn of infected animals. Although severe clinical cases can be observed, infection with RVF virus (RVFV in humans is, in most cases, asymptomatic or causes a febrile illness without serious symptoms. In small ruminants RVFV mainly causes abortion and neonatal death. The distribution of RVFV has been well documented in many African countries, particularly in the north (Egypt, Sudan, east (Kenya, Tanzania, Somalia, west (Senegal, Mauritania and south (South Africa, but also in the Indian Ocean (Madagascar, Mayotte and the Arabian Peninsula. In contrast, the prevalence of RVFV has rarely been investigated in central African countries. METHODOLOGY/PRINCIPAL FINDINGS: We therefore conducted a large serological survey of rural populations in Gabon, involving 4,323 individuals from 212 randomly selected villages (10.3% of all Gabonese villages. RVFV-specific IgG was found in a total of 145 individuals (3.3% suggesting the wide circulation of Rift Valley fever virus in Gabon. The seroprevalence was significantly higher in the lakes region than in forest and savannas zones, with respective rates of 8.3%, 2.9% and 2.2%. In the lakes region, RVFV-specific IgG was significantly more prevalent in males than in females (respectively 12.8% and 3.8% and the seroprevalence increased gradually with age in males but not in females. CONCLUSIONS/SIGNIFICANCE: Although RVFV was suggested to circulate at a relatively high level in Gabon, no outbreaks or even isolated cases have been documented in the country. The higher prevalence in the lakes region is likely to be driven by specific ecologic conditions favorable to certain mosquito vector species. Males may be more at risk of infection than females because they spend more time farming and

Impact of the Rhône and Durance valleys on sea-breeze circulation in the Marseille area

Science.gov (United States)

Bastin, Sophie; Drobinski, Philippe; Dabas, Alain; Delville, Patricia; Reitebuch, Oliver; Werner, Christian

2005-03-01

Sea-breeze dynamics in the Marseille area, in the south of France, is investigated in the framework of the ESCOMPTE experiment conducted during summer 2001 in order to evaluate the role of thermal circulations on pollutant transport and ventilation. Under particular attention in this paper is the sea-breeze channelling by the broad Rhône valley and the narrow Durance valley, both oriented nearly-north-south, i.e., perpendicular to the coastline, and its possible impact on the sea-breeze penetration, intensity and depth, which are key information for air pollution issues. One situation of slight synoptic pressure gradient leading to a northerly flow in the Rhône valley (25 June 2001) and one situation of a weak onshore prevailing synoptic wind (26 June 2001) are compared. The impact of the Rhône and Durance valleys on the sea-breeze dynamics on these two typical days is generalized to the whole ESCOMPTE observing period. The present study shows by combining simple scaling analysis with wind data from meteorological surface stations and Doppler lidars that (i) the Durance valley always affects the sea breeze by accelerating the flow. A consequence is that the Durance valley contributes to weaken the temperature gradient along the valley and thus the sea-breeze circulation. In some cases, the acceleration of the channelled flow in the Durance valley suppresses the sea-breeze flow by temperature gradient inhibition; (ii) the Rhône valley does not generally affect the sea breeze significantly. However, if the sea breeze is combined with an onshore flow, it leads to further penetration inland and intensification of the low-level southerly flow. In this situation, lateral constriction may accelerate the sea breeze. Simple scaling analysis suggests that Saint Paul (44.35°N, about 100 km from the coastline) is the lower limit where sea breeze can be affected by the Rhône valley. These conclusions have implications in air quality topics as channelled sea breeze may

Inter-epidemic abundance and distribution of potential mosquito vectors for Rift Valley fever virus in Ngorongoro district, Tanzania

OpenAIRE

Mweya, Clement N.; Kimera, Sharadhuli I.; Mellau, Lesakit S. B.; Mboera, Leonard E. G.

2015-01-01

Background: Rift Valley fever (RVF) is a mosquito-borne viral zoonosis that primarily affects ruminants but also has the capacity to infect humans. Objective: To determine the abundance and distribution of mosquito vectors in relation to their potential role in the virus transmission and maintenance in disease epidemic areas of Ngorongoro district in northern Tanzania. Methods: A cross-sectional entomological investigation was carried out before the suspected RVF outbreak in October 2012. Mos...

Mantle convection patterns reveal the enigma of the Red Sea rifting

Science.gov (United States)

Petrunin, Alexey; Kaban, Mikhail; El Khrepy, Sami; Al-Arifi, Nassir

2017-04-01

Initiation and further development of the Red Sea rift (RSR) is usually associated with the Afar plume at the Oligocene-Miocene separating the Arabian plate from the rest of the continent. Usually, the RSR is divided into three parts with different geological, tectonic and geophysical characteristics, but the nature of this partitioning is still debatable. To understand origin and driving forces responsible for the tectonic partitioning of the RSR, we have developed a global mantle convection model based on the refined density model and viscosity distribution derived from tectonic, rheological and seismic data. The global density model of the upper mantle is refined for the Middle East based on the high-resolution 3D model (Kaban et al., 2016). This model based on a joint inversion of the residual gravity and residual topography provides much better constraints on the 3D density structure compared to the global model based on seismic tomography. The refined density model and the viscosity distribution based on a homologous temperature approach provide an initial setup for further numerical calculations. The present-day snapshot of the mantle convection is calculated by using the code ProSpher 3D that allows for strong lateral variations of viscosity (Petrunin et al., 2013). The setup includes weak plate boundaries, while the measured GPS velocities are used to constrain the solution. The resulting mantle flow patterns show clear distinctions among the mantle flow patterns below the three parts of the RSR. According to the modeling results, tectonics of the southern part of the Red Sea is mainly determined by the Afar plume and the Ethiopian rift opening. It is characterized by a divergent mantle flow, which is connected to the East African Rift activity. The rising mantle flow is traced down to the transition zone and continues in the lower mantle for a few thousand kilometers south-west of Afar. The hot mantle anomaly below the central part of the RSR can be

Blood Meal Analysis of and Virus Detection in Mosquitoes Collected during a Rift Valley fever Epizootic/Epidemic: Implications for epidemic disease transmission dynamics

Science.gov (United States)

Rift Valley fever (RVF) is a zoonosis of domestic ruminants in Africa. Bloodfed mosquitoes collected during the 2006-2007 RVF outbreak in Kenya were analyzed to determine the virus infection status and animal source of the bloodmeals. Bloodmeals from individual mosquito abdomens were screened for v...

Continental rupture and the creation of new crust in the Salton Trough rift, Southern California and northern Mexico: Results from the Salton Seismic Imaging Project

Science.gov (United States)

Han, Liang; Hole, John A.; Stock, Joann M.; Fuis, Gary S.; Kell, Annie; Driscoll, Neal W.; Kent, Graham M.; Harding, Alistair J.; Rymer, Michael J.; González-Fernández, Antonio; Lázaro-Mancilla, Octavio

2016-10-01

A refraction and wide-angle reflection seismic profile along the axis of the Salton Trough, California and Mexico, was analyzed to constrain crustal and upper mantle seismic velocity structure during active continental rifting. From the northern Salton Sea to the southern Imperial Valley, the crust is 17-18 km thick and approximately one-dimensional. The transition at depth from Colorado River sediment to underlying crystalline rock is gradual and is not a depositional surface. The crystalline rock from 3 to 8 km depth is interpreted as sediment metamorphosed by high heat flow. Deeper felsic crystalline rock could be stretched preexisting crust or higher-grade metamorphosed sediment. The lower crust below 12 km depth is interpreted to be gabbro emplaced by rift-related magmatic intrusion by underplating. Low upper mantle velocity indicates high temperature and partial melting. Under the Coachella Valley, sediment thins to the north and the underlying crystalline rock is interpreted as granitic basement. Mafic rock does not exist at 12-18 km depth as it does to the south, and a weak reflection suggests Moho at 28 km depth. Structure in adjacent Mexico has slower midcrustal velocity, and rocks with mantle velocity must be much deeper than in the Imperial Valley. Slower velocity and thicker crust in the Coachella and Mexicali valleys define the rift zone between them to be >100 km wide in the direction of plate motion. North American lithosphere in the central Salton Trough has been rifted apart and is being replaced by new crust created by magmatism, sedimentation, and metamorphism.

Continental rupture and the creation of new crust in the Salton Trough rift, southern California and northern Mexico: Results from the Salton Seismic Imaging Project

Science.gov (United States)

Han, Liang; Hole, John A.; Stock, Joann M.; Fuis, Gary S.; Kell, Annie; Driscoll, Neal W.; Kent, Graham M.; Rymer, Michael J.; Gonzalez-Fernandez, Antonio; Aburto-Oropeza, Octavio

2016-01-01

A refraction and wide-angle reflection seismic profile along the axis of the Salton Trough, California and Mexico, was analyzed to constrain crustal and upper mantle seismic velocity structure during active continental rifting. From the northern Salton Sea to the southern Imperial Valley, the crust is 17-18 km thick and approximately one-dimensional. The transition at depth from Colorado River sediment to underlying crystalline rock is gradual and is not a depositional surface. The crystalline rock from ~3 to ~8 km depth is interpreted as sediment metamorphosed by high heat flow. Deeper felsic crystalline rock could be stretched pre-existing crust or higher grade metamorphosed sediment. The lower crust below ~12 km depth is interpreted to be gabbro emplaced by rift-related magmatic intrusion by underplating. Low upper-mantle velocity indicates high temperature and partial melting. Under the Coachella Valley, sediment thins to the north and the underlying crystalline rock is interpreted as granitic basement. Mafic rock does not exist at 12-18 depth as it does to the south, and a weak reflection suggests Moho at ~28 km depth. Structure in adjacent Mexico has slower mid-crustal velocity and rocks with mantle velocity must be much deeper than in the Imperial Valley. Slower velocity and thicker crust in the Coachella and Mexicali valleys define the rift zone between them to be >100 km wide in the direction of plate motion. North American lithosphere in the central Salton Trough has been rifted apart and is being replaced by new crust created by magmatism, sedimentation, and metamorphism.

Ultrastructural study of Rift Valley fever virus in the mouse model

Energy Technology Data Exchange (ETDEWEB)

Reed, Christopher; Steele, Keith E.; Honko, Anna; Shamblin, Joshua; Hensley, Lisa E. [United States Army Medical Research Institute of Infectious Diseases (USAMRIID), Fort Detrick, MD (United States); Smith, Darci R., E-mail: darci.smith1@us.army.mil [United States Army Medical Research Institute of Infectious Diseases (USAMRIID), Fort Detrick, MD (United States)

2012-09-15

Detailed ultrastructural studies of Rift Valley fever virus (RVFV) in the mouse model are needed to develop and characterize a small animal model of RVF for the evaluation of potential vaccines and therapeutics. In this study, the ultrastructural features of RVFV infection in the mouse model were analyzed. The main changes in the liver included the presence of viral particles in hepatocytes and hepatic stem cells accompanied by hepatocyte apoptosis. However, viral particles were observed rarely in the liver; in contrast, particles were extremely abundant in the CNS. Despite extensive lymphocytolysis, direct evidence of viral replication was not observed in the lymphoid tissue. These results correlate with the acute-onset hepatitis and delayed-onset encephalitis that are dominant features of severe human RVF, but suggest that host immune-mediated mechanisms contribute significantly to pathology. The results of this study expand our knowledge of RVFV-host interactions and further characterize the mouse model of RVF.

Ultrastructural study of Rift Valley fever virus in the mouse model

International Nuclear Information System (INIS)

Reed, Christopher; Steele, Keith E.; Honko, Anna; Shamblin, Joshua; Hensley, Lisa E.; Smith, Darci R.

2012-01-01

Detailed ultrastructural studies of Rift Valley fever virus (RVFV) in the mouse model are needed to develop and characterize a small animal model of RVF for the evaluation of potential vaccines and therapeutics. In this study, the ultrastructural features of RVFV infection in the mouse model were analyzed. The main changes in the liver included the presence of viral particles in hepatocytes and hepatic stem cells accompanied by hepatocyte apoptosis. However, viral particles were observed rarely in the liver; in contrast, particles were extremely abundant in the CNS. Despite extensive lymphocytolysis, direct evidence of viral replication was not observed in the lymphoid tissue. These results correlate with the acute-onset hepatitis and delayed-onset encephalitis that are dominant features of severe human RVF, but suggest that host immune-mediated mechanisms contribute significantly to pathology. The results of this study expand our knowledge of RVFV–host interactions and further characterize the mouse model of RVF.

Identification of potential vectors of and detection of antibodies against Rift Valley fever virus in livestock during interepizootic periods.

Science.gov (United States)

Rostal, Melinda K; Evans, Alina L; Sang, Rosemary; Gikundi, Solomon; Wakhule, Lilian; Munyua, Peninah; Macharia, Joseph; Feikin, Daniel R; Breiman, Robert F; Njenga, M Kariuki

2010-05-01

To evaluate the prevalence of Rift Valley fever virus (RVFV) antibodies in livestock and presence of competent mosquito vectors of RVFV during an interepizootic period (IEP) in Kenya. 208 sheep and 84 goats ranging in age from 4 months to 15 years, from 2 breeding herds. Blood specimens were collected from the sheep and goats during the 1999-2006 IEP in Rift Valley Province, and serum was harvested. Serum specimens were tested for IgG and IgM antibodies against RVFV by use of an ELISA. In addition, 7,134 mosquitoes were trapped in Naivasha, Nairobi, and Northeastern Province, and speciation was performed. No animals were seropositive for IgM against RVFV. Of the animals born after the 1997-1998 epizootic, 18% (34/188) of sheep were seropositive for IgG against RVFV, compared with 3% (2/75) of goats. Seventy percent (8,144/11,678) of the mosquitoes collected were of the Culex subgenera; 18% (2,102/11,678) were Aedes spp. Detection of IgG in the sera of sheep and goats born after the 1997-1998 epizootic and before the 2006 epizootic indicated that virus activity existed during the IEP. Detection of Aedes mosquitoes, which are competent vectors of RVFV, suggested that a cryptic vector-to-vertebrate cycle may exist during IEPs.

Rift Valley Fever Risk Map Model and Seroprevalence in Selected Wild Ungulates and Camels from Kenya

Science.gov (United States)

Britch, Seth C.; Binepal, Yatinder S.; Ruder, Mark G.; Kariithi, Henry M.; Linthicum, Kenneth J.; Anyamba, Assaf; Small, Jennifer L.; Tucker, Compton J.; Ateya, Leonard O.; Oriko, Abuu A.;

Countermeasure development for Rift Valley fever: deletion, modification or targeting of major virulence factor NSs.

Science.gov (United States)

Lihoradova, Olga; Ikegami, Tetsuro

2014-01-01

Rift Valley fever (RVF) is a mosquito-borne zoonotic disease characterized by a high rate of abortion in ruminants, and febrile illness, hemorrhagic fever, retinitis and encephalitis in humans. RVF is caused by the RVF virus (RVFV), belonging to the genus Phlebovirus of the family Bunyaviridae . RVFV encodes a major virulence factor, NSs , which is dispensable for viral replication, yet required for evasion of host innate immune responses. RVFV NSs inhibits host gene upregulation at the transcriptional level, while promoting viral translation in the cytoplasm. In this article, we summarize the virology and pathology of RVF, and countermeasure development for RVF, with emphasis on NSs function and applications.

Rift Valley fever virus NSS gene expression correlates with a defect in nuclear mRNA export.

Science.gov (United States)

Copeland, Anna Maria; Van Deusen, Nicole M; Schmaljohn, Connie S

2015-12-01

We investigated the localization of host mRNA during Rift Valley fever virus (RVFV) infection. Fluorescence in situ hybridization revealed that infection with RVFV altered the localization of host mRNA. mRNA accumulated in the nuclei of RVFV-infected but not mock-infected cells. Further, overexpression of the NSS gene, but not the N, GN or NSM genes correlated with mRNA nuclear accumulation. Nuclear accumulation of host mRNA was not observed in cells infected with a strain of RVFV lacking the gene encoding NSS, confirming that expression of NSS is likely responsible for this phenomenon. Published by Elsevier Inc.

Fylla Bank: structure and evolution of a normal-to-shear rifted margin in the northern Labrador Sea

DEFF Research Database (Denmark)

Døssing, Arne

2011-01-01

‐strike discontinuities in oceanic crust in the Labrador Sea to define margin segmentation in southern West Greenland, including the borders of Fylla Bank. A structural‐kinematic model presented here thus suggests that the Cretaceous–Cenozoic poly‐phase rifting to some extent was controlled by pre‐existing crustal fabric......, the Bank may be compared with the Demerara Plateau, part of the French Guinea‐Northeast Brazil continental margin. Seismic reflection interpretations presented in this study show that Fylla Bank is situated above an extensive basin complex, herein referred to as Fylla Structural Complex, which contains...... an up to 5‐km‐thick Cretaceous–Cenozoic sedimentary succession above an inferred pre‐Cretaceous basement. Seismic mapping of basement structures show that the complex is dominated by NNW‐/NW‐striking rift basins in its southern part and NNE‐striking rift basins in its northern part. The rift basins...

Infection of inbred rat strains with Rift Valley fever virus: development of a congenic resistant strain and observations on age-dependence of resistance.

Science.gov (United States)

Anderson, G W; Rosebrock, J A; Johnson, A J; Jennings, G B; Peters, C J

1991-05-01

A congenic rat strain (WF.LEW) was derived from the susceptible Wistar-Furth (WF) (background strain) and the resistant LEW (donor strain) inbred strains and was used to evaluate the phenotypic expression of a dominant Mendelian gene that confers resistance to fatal hepatic disease caused by the ZH501 strain of Rift Valley fever virus (RVFV). Resistance to hepatic disease developed gradually with age, with full expression at approximately 10 weeks in the WF.LEW and LEW rat strains. The ZH501 strain caused fatal hepatitis in WF rats regardless of age. However, resistance to the SA75 RVFV strain (relatively non-pathogenic for adult rats), was age- and dose-dependent in both WF and LEW rats. The resistance gene transferred to the newly derived WF.LEW congenic rat strain appears to amplify age-dependent resistance of adult rats, resulting in protection against fatal hepatic disease caused by the virulent ZH501 strain. The congenic rat strain will be a valuable asset in elucidating the mechanism of resistance to Rift Valley fever virus governed by the dominant Mendelian gene.

Foehn-induced effects on local dust pollution, frontal clouds and solar radiation in the Dead Sea valley

Science.gov (United States)

Kishcha, Pavel; Starobinets, Boris; Savir, Amit; Alpert, Pinhas; Kaplan, Michael

2018-06-01

Despite the long history of investigation of foehn phenomena, there are few studies of the influence of foehn winds on air pollution and none in the Dead Sea valley. For the first time the foehn phenomenon and its effects on local dust pollution, frontal cloudiness and surface solar radiation were analyzed in the Dead Sea valley, as it occurred on 22 March 2013. This was carried out using both numerical simulations and observations. The foehn winds intensified local dust emissions, while the foehn-induced temperature inversion trapped dust particles beneath this inversion. These two factors caused extreme surface dust concentration in the western Dead Sea valley. The dust pollution was transported by west winds eastward, to the central Dead Sea valley, where the speed of these winds sharply decreased. The transported dust was captured by the ascending airflow contributing to the maximum aerosol optical depth (AOD) over the central Dead Sea valley. On the day under study, the maximum surface dust concentration did not coincide with the maximum AOD: this being one of the specific effects of the foehn phenomenon on dust pollution in the Dead Sea valley. Radar data showed a passage of frontal cloudiness through the area of the Dead Sea valley leading to a sharp drop in noon solar radiation. The descending airflow over the downwind side of the Judean Mountains led to the formation of a cloud-free band followed by only the partial recovery of solar radiation because of the extreme dust pollution caused by foehn winds.

The Rift Valley fever: could re-emerge in Egypt again?

Science.gov (United States)

El-Bahnasawy, Mamdouh; Megahed, Laila Abdel-Mawla; Abdalla Saleh, Hala Ahmed; Morsy, Tosson A

2013-04-01

The Rift Valley fever (RVF) is a neglected, emerging, mosquito-borne disease with severe negative impact on human and animal health and economy. RVF is caused by RVF virus of the family of Bunyaviridae, genus Phlebovirus. RVF is an acute, febrile disease affecting humans and a wide range of animals. The virus is trans-mitted through the bites from mosquitoes and exposure to viremic blood, body fluids, or contact with tissues of infected animals or by inhaling natural virus aerosols, also possibly by consumption of infected unpasteurized milk. The RVF-virus replicate at the site introduction and in local lymphatic followed by viremia and spread to other organs as the liver and central nervous system, causing the hepatic necrosis and eosinophilia cytoplasmic degeneration. The main signs and symptoms are fever, headache, myalgia, arthralgia, photophobia, bradycardia, conjunctivitis and flushing face. Main complications include jaundice, hemorrhagic, meningoencephalitis and retinal lesions. Generally speaking, in the 21st Century, the vector-borne infectious diseases, was accepted as the disaster issues with the considerable significant morbidity and mortality. These facts should be considered by the public health, veterinary and agricultural authorities

Foehn-induced effects on dust pollution, frontal clouds and solar radiation in the Dead Sea valley

Science.gov (United States)

Kishcha, Pavel; Starobinets, Boris; Alpert, Pinhas; Kaplan, Michael

2017-04-01

The significant drying up of the Dead Sea over the past 40 years has led to an increase in an exposed area contributing to local dust pollution. Measurements show that, sometimes, in the Dead Sea valley, dust pollution can reach extreme concentrations up to several thousands of micrograms per cubic meters. Our analysis of a meteorological situation shows that a foehn phenomenon can be a causal factor for the aforementioned extreme local dust concentration. This foehn phenomenon creates strong warm and dry winds, which are accompanied by air turbulence and temperature inversion. In our study, foehn-induced effects on dust pollution, frontal clouds and solar radiation were analyzed over the Judean Mountains ( 1000 m) and over the Dead Sea valley (-420 m), using high-resolution numerical simulations and in-situ observations at meteorological stations located across the mountain ridge. An extreme dust episode occurring on March 22, 2013, was analyzed, which was characterized by measured surface dust concentrations of up to 7000 µg m-3 in the Dead Sea valley. We simulated this foehn phenomenon with the 3-km resolution COSMO-ART model. Our analysis has shown that the foehn phenomenon could be observed even over the relatively low Judean Mountains. This analysis was based on various meteorological, pyranometer, radar, and aerosol measurements together with high-resolution model data. In the Dead Sea valley, the maximum aerosol optical depth (AOD) did not coincide with the maximum surface dust concentration. This lack of coincidence indicates difficulties in using satellite-based AOD for initializing dust concentration within numerical forecast systems over this region with complex terrain. In the western Dead Sea valley, strong foehn winds of over 20 m/s were accompanied by maximal air turbulence leading to maximal local dust emissions. Thus, the model showed that, by creating significant turbulence, the foehn phenomenon intensified the saltation (bombardment) mechanism

Rift Valley fever virus epidemic in Kenya, 2006/2007: the entomologic investigations.

Science.gov (United States)

Sang, Rosemary; Kioko, Elizabeth; Lutomiah, Joel; Warigia, Marion; Ochieng, Caroline; O'Guinn, Monica; Lee, John S; Koka, Hellen; Godsey, Marvin; Hoel, David; Hanafi, Hanafi; Miller, Barry; Schnabel, David; Breiman, Robert F; Richardson, Jason

2010-08-01

In December 2006, Rift Valley fever (RVF) was diagnosed in humans in Garissa Hospital, Kenya and an outbreak reported affecting 11 districts. Entomologic surveillance was performed in four districts to determine the epidemic/epizootic vectors of RVF virus (RVFV). Approximately 297,000 mosquitoes were collected, 164,626 identified to species, 72,058 sorted into 3,003 pools and tested for RVFV by reverse transcription-polymerase chain reaction. Seventy-seven pools representing 10 species tested positive for RVFV, including Aedes mcintoshi/circumluteolus (26 pools), Aedes ochraceus (23 pools), Mansonia uniformis (15 pools); Culex poicilipes, Culex bitaeniorhynchus (3 pools each); Anopheles squamosus, Mansonia africana (2 pools each); Culex quinquefasciatus, Culex univittatus, Aedes pembaensis (1 pool each). Positive Ae. pembaensis, Cx. univittatus, and Cx. bitaeniorhynchus was a first time observation. Species composition, densities, and infection varied among districts supporting hypothesis that different mosquito species serve as epizootic/epidemic vectors of RVFV in diverse ecologies, creating a complex epidemiologic pattern in East Africa.

Serologic evidence of exposure to Rift Valley fever virus detected in Tunisia

Directory of Open Access Journals (Sweden)

A. Bosworth

2016-01-01

Full Text Available Rift Valley fever virus (RVFv is capable of causing dramatic outbreaks amongst economically important animal species and is capable of causing severe symptoms and mortality in humans. RVFv is known to circulate widely throughout East Africa; serologic evidence of exposure has also been found in some northern African countries, including Mauritania. This study aimed to ascertain whether RVFv is circulating in regions beyond its known geographic range. Samples from febrile patients (n=181 and nonfebrile healthy agricultural and slaughterhouse workers (n=38 were collected during the summer of 2014 and surveyed for exposure to RVFv by both serologic tests and PCR. Of the 219 samples tested, 7.8% of nonfebrile participants showed immunoglobulin G reactivity to RVFv nucleoprotein and 8.3% of febrile patients showed immunoglobulin M reactivity, with the latter samples indicating recent exposure to the virus. Our results suggest an active circulation of RVFv and evidence of human exposure in the population of Tunisia.

A review of mosquitoes associated with Rift Valley fever virus in Madagascar.

Science.gov (United States)

Tantely, Luciano M; Boyer, Sébastien; Fontenille, Didier

2015-04-01

Rift Valley fever (RVF) is a viral zoonotic disease occurring throughout Africa, the Arabian Peninsula, and Madagascar. The disease is caused by a Phlebovirus (RVF virus [RVFV]) transmitted to vertebrate hosts through the bite of infected mosquitoes. In Madagascar, the first RVFV circulation was reported in 1979 based on detection in mosquitoes but without epidemic episode. Subsequently, two outbreaks occurred: the first along the east coast and in the central highlands in 1990 and 1991 and the most recent along the northern and eastern coasts and in the central highlands in 2008 and 2009. Despite the presence of 24 mosquitoes species potentially associated with RVFV transmission in Madagascar, little associated entomological information is available. In this review, we list the RVFV vector, Culex antennatus, as well as other taxa as candidate vector species. We discuss risk factors from an entomological perspective for the re-emergence of RVF in Madagascar. © The American Society of Tropical Medicine and Hygiene.

Rift Valley fever virus NSs inhibits host transcription independently of the degradation of dsRNA-dependent Protein Kinase PKR

OpenAIRE

Kalveram, Birte; Lihoradova, Olga; Indran, Sabarish V.; Lokugamage, Nandadeva; Head, Jennifer A.; Ikegami, Tetsuro

2012-01-01

Rift Valley fever virus (RVFV) encodes one major virulence factor, the NSs protein. NSs suppresses host general transcription, including interferon (IFN)-β mRNA synthesis, and promotes degradation of the dsRNA-dependent protein kinase (PKR). We generated a novel RVFV mutant (rMP12-NSsR173A) specifically lacking the function to promote PKR degradation. rMP12-NSsR173A infection induces early phosphorylation of eIF2α through PKR activation, while retaining the function to inhibit host general tr...

Concentration of strain in a marginal rift zone of the Japan backarc during post-rift compression

Science.gov (United States)

Sato, H.; Ishiyama, T.; Kato, N.; Abe, S.; Shiraishi, K.; Inaba, M.; Kurashimo, E.; Iwasaki, T.; Van Horne, A.; No, T.; Sato, T.; Kodaira, S.; Matsubara, M.; Takeda, T.; Abe, S.; Kodaira, C.

2015-12-01

Late Cenozoic deformation zones in Japan may be divided into two types: (1) arc-arc collision zones like those of Izu and the Hokkaido axial zone, and (2) reactivated back-arc marginal rift (BMR) systems. A BMR develops during a secondary rifting event that follows the opening of a back-arc basin. It forms close to the volcanic front and distant from the spreading center of the basin. In Japan, a BMR system developed along the Sea of Japan coast following the opening of the Japan Sea. The BMR appears to be the weakest, most deformable part of the arc back-arc system. When active rifting in the marginal basins ended, thermal subsidence, and then mechanical subsidence related to the onset of a compressional stress regime, allowed deposition of up to 5 km of post-rift, deep-marine to fluvial sedimentation. Continued compression produced fault-related folds in the post-rift sediments, in thin-skin style deformation. Shortening reached a maximum in the BMR system compared to other parts of the back-arc, suggesting that it is the weakest part of the entire system. We examined the structure of the BMR system using active source seismic investigation and earthquake tomography. The velocity structure beneath the marginal rift basin shows higher P-wave velocity in the upper mantle/lower crust which suggests significant mafic intrusion and thinning of the upper continental crust. The syn-rift mafic intrusive forms a convex shape, and the boundary between the pre-rift crust and the mafic intrusive dips outward. In the post-rift compressional stress regime, the boundary of the mafic body reactivated as a reverse fault, forming a large-scale wedge thrust and causing further subsidence of the rift basin. The driver of the intense shortening event along the Sea of Japan coast in SW Japan was the arrival of a buoyant young (15 Ma) Shikoku basin at the Nankai Trough. Subduction stalled and the backarc was compressed. As the buoyant basin cooled, subduction resumed, and the rate of

Risk analysis of inter-species reassortment through a Rift Valley fever phlebovirus MP-12 vaccine strain.

Directory of Open Access Journals (Sweden)

Hoai J Ly

Full Text Available Rift Valley fever (RVF is a mosquito-borne zoonotic disease endemic to Africa and the Arabian Peninsula. The causative agent, Rift Valley fever phlebovirus (RVFV, belongs to the genus Phlebovirus in the family Phenuiviridae and causes high rates of abortions in ruminants, and hemorrhagic fever, encephalitis, or blindness in humans. Viral maintenance by mosquito vectors has led to sporadic RVF outbreaks in ruminants and humans in endemic countries, and effective vaccination of animals and humans may minimize the impact of this disease. A live-attenuated MP-12 vaccine strain is one of the best characterized RVFV strains, and was conditionally approved as a veterinary vaccine in the U.S. Live-attenuated RVF vaccines including MP-12 strain may form reassortant strains with other bunyavirus species. This study thus aimed to characterize the occurrence of genetic reassortment between the MP-12 strain and bunyavirus species closely related to RVFV. The Arumowot virus (AMTV and Gouleako goukovirus (GOLV, are transmitted by mosquitoes in Africa. The results of this study showed that GOLV does not form detectable reassortant strains with the MP-12 strain in co-infected C6/36 cells. The AMTV also did not form any reassortant strains with MP-12 strain in co-infected C6/36 cells, due to the incompatibility among N, L, and Gn/Gc proteins. A lack of reassortant formation could be due to a functional incompatibility of N and L proteins derived from heterologous species, and due to a lack of packaging via heterologous Gn/Gc proteins. The MP-12 strain did, however, randomly exchange L-, M-, and S-segments with a genetic variant strain, rMP12-GM50, in culture cells. The MP-12 strain is thus unlikely to form any reassortant strains with AMTV or GOLV in nature.

Culex pipiens, an experimental efficient vector of West Nile and Rift Valley fever viruses in the Maghreb region.

Directory of Open Access Journals (Sweden)

Fadila Amraoui

Full Text Available West Nile fever (WNF and Rift Valley fever (RVF are emerging diseases causing epidemics outside their natural range of distribution. West Nile virus (WNV circulates widely and harmlessly in the old world among birds as amplifying hosts, and horses and humans as accidental dead-end hosts. Rift Valley fever virus (RVFV re-emerges periodically in Africa causing massive outbreaks. In the Maghreb, eco-climatic and entomologic conditions are favourable for WNV and RVFV emergence. Both viruses are transmitted by mosquitoes belonging to the Culex pipiens complex. We evaluated the ability of different populations of Cx. pipiens from North Africa to transmit WNV and the avirulent RVFV Clone 13 strain. Mosquitoes collected in Algeria, Morocco, and Tunisia during the summer 2010 were experimentally infected with WNV and RVFV Clone 13 strain at titers of 10(7.8 and 10(8.5 plaque forming units/mL, respectively. Disseminated infection and transmission rates were estimated 14-21 days following the exposure to the infectious blood-meal. We show that 14 days after exposure to WNV, all mosquito st developed a high disseminated infection and were able to excrete infectious saliva. However, only 69.2% of mosquito strains developed a disseminated infection with RVFV Clone 13 strain, and among them, 77.8% were able to deliver virus through saliva. Thus, Cx. pipiens from the Maghreb are efficient experimental vectors to transmit WNV and to a lesser extent, RVFV Clone 13 strain. The epidemiologic importance of our findings should be considered in the light of other parameters related to mosquito ecology and biology.

230Th/234U dating of the quaternary spring travertines in the Arava Rift Valley of Israel and paleoclimatic implications

International Nuclear Information System (INIS)

Kronfeld, J.

1988-07-01

Springs and lake deposits (travertines) sampled along the western margins of the Arava segment of the Dead Sea Rift Valley, Israel, were studied as a potential source of palaeoclimatic information. The 230 Th/ 234 U disequilibrium method was used to determine the age of the investigated deposits. The radiometric dating was supplemented by detailed petrographic and chemical analyses of the collected samples. Detailed petrographic observations of the analysed travertine samples suggest their deposition under moderately-arid conditions, alternating with arid to extremely arid periods. This evidence is consistent with the preliminary conclusions drawn from palynological studies in the area. Dating by the 230 Th/ 234 U disequilibrium method indicates that most travertine ages correspond to oceanic 18 O stages 5 and 7. The good correspondence between apparent ages as deduced from the position of the travertines in vertical and lateral successions and the radiometric ages, lends credibility to the radiometric ages. The clustering of ages during the warm 18 O stages bears similarity to the temporal distribution of middle to late Pleistocene sapropelic horizons in the Eastern Mediterranean Basin which further leads to suspicion that during insolation maxima monsoonal cells originating in the Indian Ocean have shifted northwards reaching the latitude of the Arava and Negev Highlands. Refs and figs

Energy Balance, Evapo-transpiration and Dew deposition in the Dead Sea Valley

Science.gov (United States)

Metzger, Jutta; Corsmeier, Ulrich

2016-04-01

The Dead Sea is a unique place on earth. It is a terminal hypersaline lake, located at the lowest point on earth with a lake level of currently -429 m above mean sea level (amsl). It is located in a transition zone of semiarid to arid climate conditions, which makes it highly sensible to climate change (Alpert1997, Smiatek2011). The Virtual Institute DEad SEa Research Venue (DESERVE) is an international project funded by the German Helmholtz Association and was established to study coupled atmospheric hydrological, and lithospheric processes in the changing environment of the Dead Sea. At the moment the most prominent environmental change is the lake level decline of approximately 1 m / year due to anthropogenic interferences (Gertman, 2002). This leads to noticeable changes in the fractions of the existing terrestrial surfaces - water, bare soil and vegetated areas - in the valley. Thus, the partitioning of the net radiation in the valley changes as well. To thoroughly study the atmospheric and hydrological processes in the Dead Sea valley, which are driven by the energy balance components, sound data of the energy fluxes of the different surfaces are necessary. Before DESERVE no long-term monitoring network simultaneously measuring the energy balance components of the different surfaces in the Dead Sea valley was available. Therefore, three energy balance stations were installed at three characteristic sites at the coast-line, over bare soil, and within vegetation, measuring all energy balance components by using the eddy covariance method. The results show, that the partitioning of the energy into sensible and latent heat flux on a diurnal scale is totally different at the three sites. This results in gradients between the sites, which are e.g. responsible for the typical diurnal wind systems at the Dead Sea. Furthermore, driving forces of evapo-transpiration at the sites were identified and a detailed analysis of the daily evaporation and dew deposition rates

Inter-epidemic acquisition of Rift Valley fever virus in humans in Tanzania.

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Robert David Sumaye

2015-02-01

Full Text Available BACKGROUND: In East Africa, epidemics of Rift Valley fever (RVF occur in cycles of 5-15 years following unusually high rainfall. RVF transmission during inter-epidemic periods (IEP generally passes undetected in absence of surveillance in mammalian hosts and vectors. We studied IEP transmission of RVF and evaluated the demographic, behavioural, occupational and spatial determinants of past RVF infection. METHODOLOGY: Between March and August 2012 we collected blood samples, and administered a risk factor questionnaire among 606 inhabitants of 6 villages in the seasonally inundated Kilombero Valley, Tanzania. ELISA tests were used to detect RVFV IgM and IgG antibodies in serum samples. Risk factors were examined by mixed effects logistic regression. FINDINGS: RVF virus IgM antibodies, indicating recent RVFV acquisition, were detected in 16 participants, representing 2.6% overall and in 22.5% of inhibition ELISA positives (n = 71. Four of 16 (25.0% IgM positives and 11/71 (15.5% of individuals with inhibition ELISA sero-positivity reported they had had no previous contact with host animals. Sero-positivity on inhibition ELISA was 11.7% (95% CI 9.2-14.5 and risk was elevated with age (odds ratio (OR 1.03 per year; 95% CI 1.01-1.04, among milkers (OR 2.19; 95% CI 1.23-3.91, and individuals eating raw meat (OR 4.17; 95% CI 1.18-14.66. Households keeping livestock had a higher probability of having members with evidence of past infection (OR = 3.04, 95% CI = 1.42-6.48 than those that do not keep livestock. CONCLUSION: There is inter-epidemic acquisition of RVFV in Kilombero Valley inhabitants. In the wake of declining malaria incidence, these findings underscore the need for clinicians to consider RVF in the differential diagnosis for febrile illnesses. Several types of direct contact with livestock are important risk factors for past infection with RVFV in this study's population. However, at least part of RVFV transmission appears to have occurred

Chimpanzee insectivory in the northern half of Uganda's Rift Valley: do Bulindi chimpanzees conform to a regional pattern?

Science.gov (United States)

McLennan, Matthew R

2014-04-01

Insects are a nutritious food source for many primates. In chimpanzees, insectivory is most prevalent among communities that manufacture tools to harvest social insects, particularly ants and termites. In contrast to other long-term study sites, chimpanzees (Pan troglodytes schweinfurthii) in Budongo Forest and Kibale National Park, Uganda, rarely eat insects and have small foraging tool kits, supporting speculation that infrequent insectivory--technically aided or otherwise--characterises chimpanzees in this part of Uganda's Rift Valley. To expand the dataset for this region, insect foraging was investigated at Bulindi (25 km from Budongo) over 19 months during two studies in 2007-2008 and 2012-2013. Systematic faecal analysis demonstrated that insectivory is a habitual foraging activity at this site. Overall levels of insect consumption varied considerably across months but were not predicted by monthly changes in rainfall or fruit intake. Unlike their Budongo and Kibale counterparts, Bulindi chimpanzees often consume ants (principally weaver ants, Oecophylla longinoda) and use sticks to dig out stingless bee (Meliponini) ground nests. In other respects, however, insectivory at Bulindi conforms to the pattern observed elsewhere in this region: they do not manufacture 'fishing' or 'dipping' tools to harvest termites and aggressive or hard-to-access ants (e.g., army ants, Dorylus spp.), despite availability of suitable prey. The Bulindi data lend support to the supposition that chimpanzees in this part of the Rift Valley rarely exploit termites and Dorylus ants, apparently lacking the 'cultural knowledge' that would enable them to do so most efficiently (i.e., tool use). The study's findings contribute to current debates about the relative influence of genetics, environment and culture in shaping regional and local variability in Pan foraging ecology.

Landscape Genetics of Aedes mcintoshi (Diptera: Culicidae), an Important Vector of Rift Valley Fever Virus in Northeastern Kenya.

Science.gov (United States)

Campbell, Lindsay P; Alexander, Alana M

2017-09-01

Rift Valley fever virus (RVFV) is a vector-borne, zoonotic disease that affects humans, wild ungulates, and domesticated livestock in Africa and the Arabian Peninsula. Rift Valley fever virus exhibits interepizootic and epizootic phases, the latter defined by widespread virus occurrence in domesticated livestock. Kenya appears to be particularly vulnerable to epizootics, with 11 outbreaks occurring between 1951 and 2007. The mosquito species Aedes mcintoshi (subgenus Neomelaniconion) is an important primary vector for RVFV in Kenya. Here, we investigate associations between genetic diversity and differentiation of one regional subclade of Ae. mcintoshi in Northeastern Kenya with environmental variables, using a multivariate statistical approach. Using CO1 (cytochrome oxidase subunit 1) sequence data deposited in GenBank, we found no evidence of isolation by distance contributing to genetic differentiation across the study area. However, we did find significant CO1 subpopulation structure and associations with recent mean precipitation values. In addition, variation in genetic diversity across our seven sample sites was associated with both precipitation and percentage clay in the soil. The large number of haplotypes found in this data set indicates that a great deal of diversity remains unsampled in this region. Additional sampling across a larger geographic area, combined with next-generation sequencing approaches that better characterize the genome, would provide a more robust assessment of genetic diversity and differentiation. Further understanding of the genetic structure of Ae. mcintoshi could provide useful information regarding the potential for RVFV to spread across East African landscapes. © The Authors 2017. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Nuclear relocalization of polyadenylate binding protein during rift valley fever virus infection involves expression of the NSs gene.

Science.gov (United States)

Copeland, Anna Maria; Altamura, Louis A; Van Deusen, Nicole M; Schmaljohn, Connie S

2013-11-01

Rift Valley fever virus (RVFV), an ambisense member of the family Bunyaviridae, genus Phlebovirus, is the causative agent of Rift Valley fever, an important zoonotic infection in Africa and the Middle East. Phlebovirus proteins are translated from virally transcribed mRNAs that, like host mRNA, are capped but, unlike host mRNAs, are not polyadenylated. Here, we investigated the role of PABP1 during RVFV infection of HeLa cells. Immunofluorescence studies of infected cells demonstrated a gross relocalization of PABP1 to the nucleus late in infection. Immunofluorescence microscopy studies of nuclear proteins revealed costaining between PABP1 and markers of nuclear speckles. PABP1 relocalization was sharply decreased in cells infected with a strain of RVFV lacking the gene encoding the RVFV nonstructural protein S (NSs). To determine whether PABP1 was required for RVFV infection, we measured the production of nucleocapsid protein (N) in cells transfected with small interfering RNAs (siRNAs) targeting PABP1. We found that the overall percentage of RVFV N-positive cells was not changed by siRNA treatment, indicating that PABP1 was not required for RVFV infection. However, when we analyzed populations of cells producing high versus low levels of PABP1, we found that the percentage of RVFV N-positive cells was decreased in cell populations producing physiologic levels of PABP1 and increased in cells with reduced levels of PABP1. Together, these results suggest that production of the NSs protein during RVFV infection leads to sequestration of PABP1 in the nuclear speckles, creating a state within the cell that favors viral protein production.

Delineation of tunnel valley across the North Sea coastline, Denmark based on reflection seismic data, boreholes, TEM and Schlumberger soundings

DEFF Research Database (Denmark)

Andersen, Theis Raaschou; Jørgensen, Flemming; Christensen, Steen

Buried tunnel valleys are elongated depressions eroded into the substratum during the Pleistocene glaciations. Nine such valleys are mapped on- and offshore in a 300 km2 area located at the Danish North Sea coast. The delineation of the buried valleys is based on an extensive data set consisting......, preferred orientations, and morphology support that three of the tunnel valleys cross the North Sea coastline. It is suggested that the nine valleys were formed during at least six events that occurred through one or more pre-Weichselian glaciations. Key words: Pleistocene valleys, geophysical mapping...

Strike-slip tectonics during rift linkage

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Pagli, C.; Yun, S. H.; Ebinger, C.; Keir, D.; Wang, H.

2017-12-01

The kinematics of triple junction linkage and the initiation of transforms in magmatic rifts remain debated. Strain patterns from the Afar triple junction provide tests of current models of how rifts grow to link in area of incipient oceanic spreading. Here we present a combined analysis of seismicity, InSAR and GPS derived strain rate maps to reveal that the plate boundary deformation in Afar is accommodated primarily by extensional tectonics in the Red Sea and Gulf of Aden rifts, and does not require large rotations about vertical axes (bookshelf faulting). Additionally, models of stress changes and seismicity induced by recent dykes in one sector of the Afar triple junction provide poor fit to the observed strike-slip earthquakes. Instead we explain these patterns as rift-perpendicular shearing at the tips of spreading rifts where extensional strains terminate against less stretched lithosphere. Our results demonstrate that rift-perpendicular strike-slip faulting between rift segments achieves plate boundary linkage during incipient seafloor spreading.

Morphometric Change Detection of Lake Hawassa in the Ethiopian Rift Valley

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Yonas Abebe

2018-05-01

Full Text Available The Ethiopian Rift Valley lakes have been subjected to environmental and ecological changes due to recent development endeavors and natural phenomena, which are visible in the alterations to the quality and quantity of the water resources. Monitoring lakes for temporal and spatial alterations has become a valuable indicator of environmental change. In this regard, hydrographic information has a paramount importance. The first extensive hydrographic survey of Lake Hawassa was conducted in 1999. In this study, a bathymetric map was prepared using advances in global positioning systems, portable sonar sounder technology, geostatistics, remote sensing and geographic information system (GIS software analysis tools with the aim of detecting morphometric changes. Results showed that the surface area of Lake Hawassa increased by 7.5% in 1999 and 3.2% in 2011 from that of 1985. Water volume decreased by 17% between 1999 and 2011. Silt accumulated over more than 50% of the bed surface has caused a 4% loss of the lake’s storage capacity. The sedimentation patterns identified may have been strongly impacted by anthropogenic activities including urbanization and farming practices located on the northern, eastern and western sides of the lake watershed. The study demonstrated this geostatistical modeling approach to be a rapid and cost-effective method for bathymetric mapping.

Evaporation estimation of rift valley lakes: comparison of models.

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Melesse, Assefa M; Abtew, Wossenu; Dessalegne, Tibebe

2009-01-01

Evapotranspiration (ET) accounts for a substantial amount of the water flux in the arid and semi-arid regions of the World. Accurate estimation of ET has been a challenge for hydrologists, mainly because of the spatiotemporal variability of the environmental and physical parameters governing the latent heat flux. In addition, most available ET models depend on intensive meteorological information for ET estimation. Such data are not available at the desired spatial and temporal scales in less developed and remote parts of the world. This limitation has necessitated the development of simple models that are less data intensive and provide ET estimates with acceptable level of accuracy. Remote sensing approach can also be applied to large areas where meteorological data are not available and field scale data collection is costly, time consuming and difficult. In areas like the Rift Valley regions of Ethiopia, the applicability of the Simple Method (Abtew Method) of lake evaporation estimation and surface energy balance approach using remote sensing was studied. The Simple Method and a remote sensing-based lake evaporation estimates were compared to the Penman, Energy balance, Pan, Radiation and Complementary Relationship Lake Evaporation (CRLE) methods applied in the region. Results indicate a good correspondence of the models outputs to that of the above methods. Comparison of the 1986 and 2000 monthly lake ET from the Landsat images to the Simple and Penman Methods show that the remote sensing and surface energy balance approach is promising for large scale applications to understand the spatial variation of the latent heat flux.

Evaporation Estimation of Rift Valley Lakes: Comparison of Models

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Tibebe Dessalegne

2009-12-01

Full Text Available Evapotranspiration (ET accounts for a substantial amount of the water flux in the arid and semi-arid regions of the World. Accurate estimation of ET has been a challenge for hydrologists, mainly because of the spatiotemporal variability of the environmental and physical parameters governing the latent heat flux. In addition, most available ET models depend on intensive meteorological information for ET estimation. Such data are not available at the desired spatial and temporal scales in less developed and remote parts of the world. This limitation has necessitated the development of simple models that are less data intensive and provide ET estimates with acceptable level of accuracy. Remote sensing approach can also be applied to large areas where meteorological data are not available and field scale data collection is costly, time consuming and difficult. In areas like the Rift Valley regions of Ethiopia, the applicability of the Simple Method (Abtew Method of lake evaporation estimation and surface energy balance approach using remote sensing was studied. The Simple Method and a remote sensing-based lake evaporation estimates were compared to the Penman, Energy balance, Pan, Radiation and Complementary Relationship Lake Evaporation (CRLE methods applied in the region. Results indicate a good correspondence of the models outputs to that of the above methods. Comparison of the 1986 and 2000 monthly lake ET from the Landsat images to the Simple and Penman Methods show that the remote sensing and surface energy balance approach is promising for large scale applications to understand the spatial variation of the latent heat flux.

Rift Valley fever outbreak--Kenya, November 2006-January 2007.

Science.gov (United States)

2007-02-02

In mid-December 2006, several unexplained fatalities associated with fever and generalized bleeding were reported to the Kenya Ministry of Health (KMOH) from Garissa District in North Eastern Province (NEP). By December 20, a total of 11 deaths had been reported. Of serum samples collected from the first 19 patients, Rift Valley fever (RVF) virus RNA or immunoglobulin M (IgM) antibodies against RVF virus were found in samples from 10 patients; all serum specimens were negative for yellow fever, Ebola, Crimean-Congo hemorrhagic fever, and dengue viruses. The outbreak was confirmed by isolation of RVF virus from six of the specimens. Humans can be infected with RVF virus from bites of mosquitoes or other arthropod vectors that have fed on animals infected with RVF virus, or through contact with viremic animals, particularly livestock. Reports of livestock deaths and unexplained animal abortions in NEP provided further evidence of an RVF outbreak. On December 20, an investigation was launched by KMOH, the Kenya Field Epidemiology and Laboratory Training Program (FELTP), the Kenya Medical Research Institute (KEMRI), the Walter Reed Project of the U.S. Army Medical Research Unit, CDC-Kenya's Global Disease Detection Center, and other partners, including the World Health Organization (WHO) and Médecins Sans Frontières (MSF). This report describes the findings from that initial investigation and the control measures taken in response to the RVF outbreak, which spread to multiple additional provinces and districts, resulting in 404 cases with 118 deaths as of January 25, 2007.

Rift Valley fever virus infection in golden Syrian hamsters.

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Dionna Scharton

Full Text Available Rift Valley fever virus (RVFV is a formidable pathogen that causes severe disease and abortion in a variety of livestock species and a range of disease in humans that includes hemorrhagic fever, fulminant hepatitis, encephalitis and blindness. The natural transmission cycle involves mosquito vectors, but exposure can also occur through contact with infected fluids and tissues. The lack of approved antiviral therapies and vaccines for human use underlies the importance of small animal models for proof-of-concept efficacy studies. Several mouse and rat models of RVFV infection have been well characterized and provide useful systems for the study of certain aspects of pathogenesis, as well as antiviral drug and vaccine development. However, certain host-directed therapeutics may not act on mouse or rat pathways. Here, we describe the natural history of disease in golden Syrian hamsters challenged subcutaneously with the pathogenic ZH501 strain of RVFV. Peracute disease resulted in rapid lethality within 2 to 3 days of RVFV challenge. High titer viremia and substantial viral loads were observed in most tissues examined; however, histopathology and immunostaining for RVFV antigen were largely restricted to the liver. Acute hepatocellular necrosis associated with a strong presence of viral antigen in the hepatocytes indicates that fulminant hepatitis is the likely cause of mortality. Further studies to assess the susceptibility and disease progression following respiratory route exposure are warranted. The use of the hamsters to model RVFV infection is suitable for early stage antiviral drug and vaccine development studies.

ALVIN-SeaBeam studies of the Sumisu Rift, Izu-Bonin arc

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Taylor, B.; Brown, G.; Fryer, P.; Gill, J. B.; Hochstaedter, A. G.; Hotta, H.; Langmuir, C. H.; Leinen, M.; Nishimura, A.; Urabe, T.

1990-10-01

Bimodal volcanism, normal faulting, rapid sedimentation, and hydrothermal circulation characterize the rifting of the Izu-Bonin arc at 31°N. Analysis of the zigzag pattern, in plan view, of the normal faults that bound Sumisu Rift indicates that the extension direction (080° ± 10°) is orthogonal to the regional trend of the volcanic front. Normal faults divide the rift into an inner rift on the arc side, which is the locus for maximum subsidence and sedimentation, and an outer rift further west. Transfer zones that link opposing master faults and/or rift flank uplifts further subdivide the rift into three segments along strike. Volcanism is concentrated along the ENE-trending transfer zone which separates the northern and central rift segments. The differential motion across the zone is accommodated by interdigitating north-trending normal faults rather than by ENE-trending oblique-slip faults. Volcanism in the outer rift has built 50-700 m high edifices without summit craters whereas in the inner rift it has formed two multi-vent en echelon ridges (the largest is 600 m high and 16 km long). The volcanism is dominantly basaltic, with compositions reflecting mantle sources little influenced by arc components. An elongate rhyolite dome and low-temperature hydrothermal deposits occur at the en echelon step in the larger ridge, which is located at the intersection of the transfer zone with the inner rift. The chimneys, veins, and crusts are composed of silica, barite and iron oxide, and are of similar composition to the ferruginous chert that mantles the Kuroko deposits. A 1.2-km transect of seven ALVIN heat flow measurements at 30°48.5'N showed that the inner-rift-bounding faults may serve as water recharge zones, but that they are not necessarily areas of focussed hydrothermal outflow, which instead occurs through the thick basin sediments. The rift basin and arc margin sediments are probably dominated by permeable rhyolitic pumice and ash erupted from submarine

Delineation of tunnel valleys across the North Sea coastline, Denmark based on reflection seismic data, boreholes, TEM and Schlumberger soundings

DEFF Research Database (Denmark)

Andersen, Theis Raaschou; Jørdensen, Flemming; Christensen, Steen

Buried tunnel valleys are elongated depressions eroded into the substratum during the Pleistocene glaciations. Nine such valleys are mapped on- and offshore in a 300 km2 area located at the Danish North Sea coast. The delineation of the buried valleys is based on an extensive data set consisting......, preferred orientations, and morphology support that three of the tunnel valleys cross the North Sea coastline. It is suggested that the nine valleys were formed during at least six events that occurred through one or more pre-Weichselian glaciations...

N-Glycans on the Rift Valley Fever Virus Envelope Glycoproteins Gn and Gc Redundantly Support Viral Infection via DC-SIGN

Science.gov (United States)

Phoenix, Inaia; Nishiyama, Shoko; Lokugamage, Nandadeva; Hill, Terence E.; Huante, Matthew B.; Slack, Olga A.L.; Carpio, Victor H.; Freiberg, Alexander N.; Ikegami, Tetsuro

2016-01-01

Rift Valley fever is a mosquito-transmitted, zoonotic disease that infects humans and ruminants. Dendritic cell specific intercellular adhesion molecule 3 (ICAM-3) grabbing non-integrin (DC-SIGN) acts as a receptor for members of the phlebovirus genus. The Rift Valley fever virus (RVFV) glycoproteins (Gn/Gc) encode five putative N-glycan sequons (asparagine (N)–any amino acid (X)–serine (S)/threonine (T)) at positions: N438 (Gn), and N794, N829, N1035, and N1077 (Gc). The N-glycosylation profile and significance in viral infection via DC-SIGN have not been elucidated. Gc N-glycosylation was first evaluated by using Gc asparagine (N) to glutamine (Q) mutants. Subsequently, we generated a series of recombinant RVFV MP-12 strain mutants, which encode N-to-Q mutations, and the infectivity of each mutant in Jurkat cells stably expressing DC-SIGN was evaluated. Results showed that Gc N794, N1035, and N1077 were N-glycosylated but N829 was not. Gc N1077 was heterogeneously N-glycosylated. RVFV Gc made two distinct N-glycoforms: “Gc-large” and “Gc-small”, and N1077 was responsible for “Gc-large” band. RVFV showed increased infection of cells expressing DC-SIGN compared to cells lacking DC-SIGN. Infection via DC-SIGN was increased in the presence of either Gn N438 or Gc N1077. Our study showed that N-glycans on the Gc and Gn surface glycoproteins redundantly support RVFV infection via DC-SIGN. PMID:27223297

Rift Valley fever virus: strategies for maintenance, survival and vertical transmission in mosquitoes.

Science.gov (United States)

Lumley, Sarah; Horton, Daniel L; Hernandez-Triana, Luis L M; Johnson, Nicholas; Fooks, Anthony R; Hewson, Roger

2017-05-01

Rift Valley fever virus (RVFV) is a mosquito-borne arbovirus causing severe disease in humans and ruminants. Spread of RVFV out of Africa has raised concerns that it could emerge in Europe or the USA. Virus persistence is dependent on successful infection of, replication in, and transmission to susceptible vertebrate and invertebrate hosts, modulated by virus-host and vector-virus interactions. The principal accepted theory for the long-term maintenance of RVFV involves vertical transmission (VT) of virus to mosquito progeny, with the virus surviving long inter-epizootic periods within the egg. This VT hypothesis, however, is yet to be comprehensively proven. Here, evidence for and against the VT of RVFV is reviewed along with the identification of factors limiting its detection in natural and experimental data. The observations of VT for other arboviruses in the genera Alphavirus, Flavivirus and Orthobunyavirus are discussed within the context of RVFV. The review concludes that VT of RVFV is likely but that current data are insufficient to irrefutably prove this hypothesis.

The geology and geophysics of the Oslo rift

Science.gov (United States)

Ruder, M. E.

1981-01-01

The regional geology and geophysical characteristics of the Oslo graben are reviewed. The graben is part of a Permian age failed continental rift. Alkali olivine, tholefitic, and monzonitic intrusives as well as basaltic lavas outline the extent of the graben. Geophysical evidence indicates that rifting activity covered a much greater area in Skagerrak Sea as well as the Paleozoic time, possibly including the northern Skagerrak Sea as well as the Oslo graben itself. Much of the surficial geologic characteristics in the southern part of the rift have since been eroded or covered by sedimentation. Geophysical data reveal a gravity maximum along the strike of the Oslo graben, local emplacements of magnetic material throughout the Skagerrak and the graben, and a slight mantle upward beneath the rift zone. Petrologic and geophysical maps which depict regional structure are included in the text. An extensive bibliography of pertinent literature published in English between 1960 and 1980 is also provided.

Discussion on final rifting evolution and breakup : insights from the Mid Norwegian - North East Greenland rifted system

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Peron-Pinvidic, Gwenn; Terje Osmundsen, Per

2016-04-01

In terms of rifted margin studies, the characteristics of the distal and outer domains are among the today's most debated questions. The architecture and composition of deep margins are rarely well constrained and hence little understood. Except from in a handful number of cases (eg. Iberia-Newfoundland, Southern Australia, Red Sea), basement samples are not available to decipher between the various interpretations allowed by geophysical models. No consensus has been reached on the basement composition, tectonic structures, sedimentary geometries or magmatic content. The result is that non-unique end-member interpretations and models are still proposed in the literature. So, although these domains mark the connection between continents and oceans, and thus correspond to unique stages in the Earth's lithospheric life cycle, their spatial and temporal evolution are still unresolved. The Norwegian-Greenland Sea rift system represents an exceptional laboratory to work on questions related to rifting, rifted margin formation and sedimentary basin evolution. It has been extensively studied for decades by both the academic and the industry communities. The proven and expected oil and gas potentials led to the methodical acquisition of world-class geophysical datasets, which permit the detailed research and thorough testing of concepts at local and regional scales. This contribution is issued from a three years project funded by ExxonMobil aiming at better understanding the crustal-scale nature and evolution of the Norwegian-Greenland Sea. The idea was to take advantage of the data availability on this specific rift system to investigate further the full crustal conjugate scale history of rifting, confronting the various available datasets. In this contribution, we will review the possible structural and sedimentary geometries of the distal margin, and their connection to the oceanic domain. We will discuss the definition of 'breakup' and introduce a first order conceptual

Geothermal exploitation activity by the United Nations in Ethiopia

Energy Technology Data Exchange (ETDEWEB)

Nakamura, H. (Geological Survey of Japan)

1971-01-01

The Rift Valley in Ethiopia was investigated for geothermal exploitation by the United Nations because it has Quaternary volcanoes which often indicate possible geothermal power generation. Preparations for the project are still being made, and the chemical analysis of hot springs is being conducted. The Rift Valley has high temperature springs and potential mineral deposits. The Danakil basin in Ethiopia which is included in the Northern Afar, has several active volcanoes made up of basalt deposits and has active hot springs. The East Africa Rift Valley, the Red Sea Rift Valley, and the Afar area are also areas suitable for investigation. Seven maps are included.

Rift Valley fever: Real or perceived threat for Zambia?

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George Dautu

2012-06-01

Full Text Available Rift Valley fever (RVF in Zambia was first reported in 1974 during an epizootic of cattle and sheep that occurred in parts of Central, Southern and Copperbelt Provinces. In 1990, the disease was documented in nine districts of the provinces of Zambia. In the last two decades, there have been no reports of RVF. This long period without reported clinical disease raises questions as to whether RVF is a current or just a perceived threat. To address this question, World Organisation for Animal Health (OIE disease occurrence data on RVF for the period 2005−2010 in the Southern Africa Development Community (SADC was analysed. From the analysis, it was evident that most countries that share a common border with Zambia had reported at least one occurrence of the disease during the period under review. Due to the absence of natural physical barriers between Zambia and most of her neighbours, informal livestock trade and movements is a ubiquitous reality. Analysis of the rainfall patterns also showed that Zambia received rains sufficient to support a mosquito population large enough for high risk of RVF transmission. The evidence of disease occurrence in nearby countries coupled with animal movement, and environmental risk suggests that RVF is a serious threat to Zambia. In conclusion, the current occurrence of RVF in Zambia is unclear, but there are sufficient indications that the magnitude of the circulating infection is such that capacity building in disease surveillance and courses on recognition of the disease for field staff is recommended. Given the zoonotic potential of RVF, these measures are also a prerequisite for accurate assessment of the disease burden in humans.

Identification of Rift Valley fever virus nucleocapsid protein-RNA binding inhibitors using a high-throughput screening assay.

Science.gov (United States)

Ellenbecker, Mary; Lanchy, Jean-Marc; Lodmell, J Stephen

2012-09-01

Rift Valley fever virus (RVFV) is an emerging infectious pathogen that causes severe disease in humans and livestock and has the potential for global spread. Currently, there is no proven effective treatment for RVFV infection, and there is no licensed vaccine. Inhibition of RNA binding to the essential viral nucleocapsid (N) protein represents a potential antiviral therapeutic strategy because all of the functions performed by N during infection involve RNA binding. To target this interaction, we developed a fluorescence polarization-based high-throughput drug-screening assay and tested 26 424 chemical compounds for their ability to disrupt an N-RNA complex. From libraries of Food and Drug Administration-approved drugs, druglike molecules, and natural product extracts, we identified several lead compounds that are promising candidates for medicinal chemistry.

Rift Valley fever phlebovirus NSs protein core domain structure suggests molecular basis for nuclear filaments.

Science.gov (United States)

Barski, Michal; Brennan, Benjamin; Miller, Ona K; Potter, Jane A; Vijayakrishnan, Swetha; Bhella, David; Naismith, James H; Elliott, Richard M; Schwarz-Linek, Ulrich

2017-09-15

Rift Valley fever phlebovirus (RVFV) is a clinically and economically important pathogen increasingly likely to cause widespread epidemics. RVFV virulence depends on the interferon antagonist non-structural protein (NSs), which remains poorly characterized. We identified a stable core domain of RVFV NSs (residues 83-248), and solved its crystal structure, a novel all-helical fold organized into highly ordered fibrils. A hallmark of RVFV pathology is NSs filament formation in infected cell nuclei. Recombinant virus encoding the NSs core domain induced intranuclear filaments, suggesting it contains all essential determinants for nuclear translocation and filament formation. Mutations of key crystal fibril interface residues in viruses encoding full-length NSs completely abrogated intranuclear filament formation in infected cells. We propose the fibrillar arrangement of the NSs core domain in crystals reveals the molecular basis of assembly of this key virulence factor in cell nuclei. Our findings have important implications for fundamental understanding of RVFV virulence.

REE partitioning between apatite and melt in a peralkaline volcanic suite, Kenya Rift Valley

Science.gov (United States)

Macdonald, R.; Baginski, B.; Belkin, H.E.; Dzierzanowski, P.; Jezak, L.

2009-01-01

Electron microprobe analyses are presented for fluorapatite phenocrysts from a benmoreite-peralkaline rhyolite volcanic suite from the Kenya Rift Valley. The rocks have previously been well characterized petrographically and their crystallization conditions are reasonably well known. The REE contents in the M site increase towards the rhyolites, with a maximum britholite component of ~35 mol.%. Chondrite-normalized REE patterns are rather flat between La and Sm and then decrease towards Yb. Sodium and Fe occupy up to 1% and 4%, respectively, of the M site. The major coupled substitution is REE3+ + Si4+ ??? Ca2+ + P5+. The substitution REE3+ + Na+ ??? 2Ca2+ has been of minor importance. The relatively large Fe contents were perhaps facilitated by the low fo2 conditions of crystallization. Zoning is ubiquitous and resulted from both fractional crystallization and magma mixing. Apatites in some rhyolites are relatively Y-depleted, perhaps reflecting crystallization from melts which had precipitated zircon. Mineral/glass (melt) ratios for two rhyolites are unusually high, with maxima at Sm (762, 1123). ?? 2008 The Mineralogical Society.

Risk factors associated with human Rift Valley fever infection: systematic review and meta-analysis.

Science.gov (United States)

Nicholas, Dennis E; Jacobsen, Kathryn H; Waters, Nigel M

2014-12-01

To identify risk factors for human Rift Valley fever virus (RVFV) infection. A systematic review identified 17 articles reporting on 16 studies examining risk factors for RVFV. Pooled odds ratios (pOR) were calculated for exposures examined in four or more studies. Being male [pOR = 1.4 (1.0, 1.8)], contact with aborted animal tissue [pOR = 3.4 (1.6, 7.3)], birthing an animal [pOR = 3.2 (2.4, 4.2)], skinning an animal [pOR = 2.5 (1.9, 3.2)], slaughtering an animal [pOR = 2.4 (1.4, 4.1)] and drinking raw milk [pOR = 1.8 (1.2, 2.6)] were significantly associated with RVF infection after meta-analysis. Other potential risk factors include sheltering animals in the home and milking an animal, which may both involve contact with animal body fluids. Based on the identified risk factors, use of personal protective equipment and disinfectants by animal handlers may help reduce RVFV transmission during outbreaks. Milk pasteurisation and other possible preventive methods require further investigation. © 2014 John Wiley & Sons Ltd.

Modeling the Impact of Climate Change on the Dynamics of Rift Valley Fever

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Saul C. Mpeshe

2014-01-01

Full Text Available A deterministic SEIR model of rift valley fever (RVF with climate change parameters was considered to compute the basic reproduction number ℛ0 and investigate the impact of temperature and precipitation on ℛ0. To study the effect of model parameters to ℛ0, sensitivity and elasticity analysis of ℛ0 were performed. When temperature and precipitation effects are not considered, ℛ0 is more sensitive to the expected number of infected Aedes spp. due to one infected livestock and more elastic to the expected number of infected livestock due to one infected Aedes spp. When climatic data are used, ℛ0 is found to be more sensitive and elastic to the expected number of infected eggs laid by Aedes spp. via transovarial transmission, followed by the expected number of infected livestock due to one infected Aedes spp. and the expected number of infected Aedes spp. due to one infected livestock for both regions Arusha and Dodoma. These results call for attention to parameters regarding incubation period, the adequate contact rate of Aedes spp. and livestock, the infective periods of livestock and Aedes spp., and the vertical transmission in Aedes species.

Modeling the Impact of Climate Change on the Dynamics of Rift Valley Fever

Science.gov (United States)

Mpeshe, Saul C.; Luboobi, Livingstone S.; Nkansah-Gyekye, Yaw

2014-01-01

A deterministic SEIR model of rift valley fever (RVF) with climate change parameters was considered to compute the basic reproduction number ℛ 0 and investigate the impact of temperature and precipitation on ℛ 0. To study the effect of model parameters to ℛ 0, sensitivity and elasticity analysis of ℛ 0 were performed. When temperature and precipitation effects are not considered, ℛ 0 is more sensitive to the expected number of infected Aedes spp. due to one infected livestock and more elastic to the expected number of infected livestock due to one infected Aedes spp. When climatic data are used, ℛ 0 is found to be more sensitive and elastic to the expected number of infected eggs laid by Aedes spp. via transovarial transmission, followed by the expected number of infected livestock due to one infected Aedes spp. and the expected number of infected Aedes spp. due to one infected livestock for both regions Arusha and Dodoma. These results call for attention to parameters regarding incubation period, the adequate contact rate of Aedes spp. and livestock, the infective periods of livestock and Aedes spp., and the vertical transmission in Aedes species. PMID:24795775

The tectonic evolution of the southeastern Terceira Rift/São Miguel region (Azores)

Science.gov (United States)

Weiß, B. J.; Hübscher, C.; Lüdmann, T.

2015-07-01

The eastern Azores Archipelago with São Miguel being the dominant subaerial structure is located at the intersection of an oceanic rift (Terceira Rift) with a major transform fault (Gloria Fault) representing the westernmost part of the Nubian-Eurasian plate boundary. The evolution of islands, bathymetric highs and basin margins involves strong volcanism, but the controlling geodynamic and tectonic processes are currently under debate. In order to study this evolution, multibeam bathymetry and marine seismic reflection data were collected to image faults and stratigraphy. The basins of the southeastern Terceira Rift are rift valleys whose southwestern and northeastern margins are defined by few major normal faults and several minor normal faults, respectively. Since São Miguel in between the rift valleys shows an unusual W-E orientation, it is supposed to be located on a leaky transform. South of the island and separated by a N120° trending graben system, the Monacco Bank represents a N160° oriented flat topped volcanic ridge dominated by tilted fault blocks. Up to six seismic units are interpreted for each basin. Although volcanic ridges hamper a direct linking of depositional strata between the rift and adjacent basins, the individual seismic stratigraphic units have distinct characteristics. Using these units to provide a consistent relative chrono-stratigraphic scheme for the entire study area, we suggest that the evolution of the southeastern Terceira Rift occurred in two stages. Considering age constrains from previous studies, we conclude that N140° structures developed orthogonal to the SW-NE direction of plate-tectonic extension before ~ 10 Ma. The N160° trending volcanic ridges and faults developed later as the plate tectonic spreading direction changed to WSW-ENE. Hence, the evolution of the southeastern Terceira Rift domain is predominantly controlled by plate kinematics and lithospheric stress forming a kind of a re-organized rift system.

Artificial Synthesis of Conserved Segment S Gene Fragment of Rift ...

African Journals Online (AJOL)

Fragment of Rift Valley Fever Virus and Preliminary Study of Its Reverse ... blindness, encephalitis, hemorrhagic hepatitis, and, in serious ... over 30 mosquito species [5] of mosquito. As ..... RVFV, as a mosquito-borne virus for a multitude.

Thermomechanical Controls on the Success and Failure of Continental Rift Systems

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Brune, S.

2017-12-01

Studies of long-term continental rift evolution are often biased towards rifts that succeed in breaking the continent like the North Atlantic, South China Sea, or South Atlantic rifts. However there are many prominent rift systems on Earth where activity stopped before the formation of a new ocean basin such as the North Sea, the West and Central African Rifts, or the West Antarctic Rift System. The factors controlling the success and failure of rifts can be divided in two groups: (1) Intrinsic processes - for instance frictional weakening, lithospheric thinning, shear heating or the strain-dependent growth of rift strength by replacing weak crust with strong mantle. (2) External processes - such as a change of plate divergence rate, the waning of a far-field driving force, or the arrival of a mantle plume. Here I use numerical and analytical modeling to investigate the role of these processes for the success and failure of rift systems. These models show that a change of plate divergence rate under constant force extension is controlled by the non-linearity of lithospheric materials. For successful rifts, a strong increase in divergence velocity can be expected to take place within few million years, a prediction that agrees with independent plate tectonic reconstructions of major Mesozoic and Cenozoic ocean-forming rift systems. Another model prediction is that oblique rifting is mechanically favored over orthogonal rifting, which means that simultaneous deformation within neighboring rift systems of different obliquity and otherwise identical properties will lead to success and failure of the more and less oblique rift, respectively. This can be exemplified by the Cretaceous activity within the Equatorial Atlantic and the West African Rifts that lead to the formation of a highly oblique oceanic spreading center and the failure of the West African Rift System. While in nature the circumstances of rift success or failure may be manifold, simplified numerical and

Constraining the dynamic response of subcontinental lithospheric mantle to rifting using Re-Os model ages in the Western Ross Sea, Antarctica

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Doherty, C.; Class, C.; Goldstein, S. L.; Shirey, S. B.; Martin, A. P.; Cooper, A. F.; Berg, J. H.; Gamble, J. A.

2012-12-01

In order to understand the dynamic response of the subcontinental lithospheric mantle (SCLM) to rifting, it is important to be able to distinguish the geochemical signatures of SCLM vs. asthenosphere. Recent work demonstrates that unradiogenic Os isotope ratios can indicate old depletion events in the convecting upper mantle (e.g. Rudnick & Walker, 2009), and allow us to make these distinctions. Thus, if SCLM can be traced across a rifted margin, its fate during rifting can be established. The Western Ross Sea provides favorable conditions to test the dynamic response of SCLM to rifting. Re-Os measurements from 8 locations extending from the rift shoulder to 200 km into the rift basin reveal 187Os/188Os ranging from 0.1056 at Foster Crater on the shoulder, to 0.1265 on Ross Island within the rift. While individual sample model ages vary widely throughout the margin, 'aluminochron' ages (Reisberg & Lorand, 1995) reveal a narrower range of lithospheric stabilization ages. Franklin Island and Sulfur Cones show a range of Re-depletion ages (603-1522 Ma and 436-1497 Ma) but aluminochrons yield Paleoproterozoic stabilization ages of 1680 Ma and 1789 Ma, respectively. These ages coincide with U-Pb zircon ages from Transantarctic Mountain (TAM) crustal rocks, in support of SCLM stabilization at the time of crust formation along the central TAM. The Paleoproterozoic stabilization age recorded at Franklin Island is especially significant, since it lies 200km off of the rift shoulder. The similar ages beneath the rift shoulder and within the rift suggests stretched SCLM reaches into the rift and thus precludes replacement by asthenospheric mantle. The persistence of thinned Paleoproterozoic SCLM into the rifted zone in WARS suggests that it represents a 'type I' margin of Huismans and Beaumont (2011), which is characterized by crustal breakup before loss of lithospheric mantle. The Archean Re-depletion age of 3.2 Ga observed on the rift shoulder suggests that cratonic

Late Miocene-Pleistocene evolution of a Rio Grande rift subbasin, Sunshine Valley-Costilla Plain, San Luis Basin, New Mexico and Colorado

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Ruleman, C.A.; Thompson, R.A.; Shroba, R.R.; Anderson, M.; Drenth, B.J.; Rotzien, J.; Lyon, J.

2013-01-01

The Sunshine Valley-Costilla Plain, a structural subbasin of the greater San Luis Basin of the northern Rio Grande rift, is bounded to the north and south by the San Luis Hills and the Red River fault zone, respectively. Surficial mapping, neotectonic investigations, geochronology, and geophysics demonstrate that the structural, volcanic, and geomorphic evolution of the basin involves the intermingling of climatic cycles and spatially and temporally varying tectonic activity of the Rio Grande rift system. Tectonic activity has transferred between range-bounding and intrabasin faults creating relict landforms of higher tectonic-activity rates along the mountain-piedmont junction. Pliocene–Pleistocene average long-term slip rates along the southern Sangre de Cristo fault zone range between 0.1 and 0.2 mm/year with late Pleistocene slip rates approximately half (0.06 mm/year) of the longer Quaternary slip rate. During the late Pleistocene, climatic influences have been dominant over tectonic influences on mountain-front geomorphic processes. Geomorphic evidence suggests that this once-closed subbasin was integrated into the Rio Grande prior to the integration of the once-closed northern San Luis Basin, north of the San Luis Hills, Colorado; however, deep canyon incision, north of the Red River and south of the San Luis Hills, initiated relatively coeval to the integration of the northern San Luis Basin.Long-term projections of slip rates applied to a 1.6 km basin depth defined from geophysical modeling suggests that rifting initiated within this subbasin between 20 and 10 Ma. Geologic mapping and geophysical interpretations reveal a complex network of northwest-, northeast-, and north-south–trending faults. Northwest- and northeast-trending faults show dual polarity and are crosscut by north-south– trending faults. This structural model possibly provides an analog for how some intracontinental rift structures evolve through time.

Knowledge, attitudes and practices on Rift Valley fever among agro pastoral communities in Kongwa and Kilombero districts, Tanzania.

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Shabani, Sasita S; Ezekiel, Mangi J; Mohamed, Mohamed; Moshiro, Candida S

2015-08-21

Rift valley fever (RVF) is a re-emerging viral vector-borne disease with rapid global socio-economic impact. A large RVF outbreak occurred in Tanzania in 2007 and affected more than half of the regions with high (47 %) case fatality rate. Little is known about RVF and its dynamics. A cross sectional study was conducted to assess the knowledge, attitudes and practices regarding RVF in Kongwa and Kilombero districts, Tanzania. We conducted a cross sectional survey among a randomly selected sample of individuals in 2011. We administered questionnaires to collect data on demographic characteristics, knowledge on symptoms, mode of transmission, prevention, attitudes and health seeking practices. A total of 463 community members participated in this study. The mean (±SD) age was 39.8 ± 14.4 years and 238 (51.4 %) were female. Majority of respondents had heard of RVF. However, only 8.8 % knew that mosquitoes were transmitting vectors. Male respondents were more likely to have greater knowledge about RVF. A small proportion mentioned clinical signs and symptoms of RVF in animals while 73.7 % mentioned unhealthy practices related to handling and consumption of dead animals. Thorough boiling of milk and cooking of meat were commonly mentioned as preventive measures for RVF. Majority (74.6 %) sought care for febrile illness at health facilities. Few (24.3 %) reported the use of protective gears to handle dead/sick animal while 15.5 % were consuming dead animals. Our study highlights the need to address the limited knowledge about RVF and promoting appropriate and timely health seeking practices. Rift valley fever outbreaks can be effectively managed with collaborative efforts of lay and professional communities with a shared perception that it poses a serious threat to public and animal health. The fact that this study was conducted in "high risk transmission areas" warrants further inquiry in other geographic regions with relatively low risk of RVF.

Lake Afrera, a structural depression in the Northern Afar Rift (Red Sea).

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Bonatti, Enrico; Gasperini, Elia; Vigliotti, Luigi; Lupi, Luca; Vaselli, Orlando; Polonia, Alina; Gasperini, Luca

2017-05-01

The boundary between the African and Arabian plates in the Southern Red Sea region is displaced inland in the northern Afar rift, where it is marked by the Red Sea-parallel Erta Ale, Alaita, and Tat Ali volcanic ridges. The Erta Ale is offset by about 20 and 40 km from the two en echelon ridges to the south. The offset area is highly seismic and marked by a depression filled by lake Afrera, a saline body of water fed by hydrothermal springs. Acoustic bathymetric profiles show ≈80 m deep canyons parallel to the NNW shore of the lake, part of a system of extensional normal faults striking parallel to the Red Sea. This system is intersected by oblique structures, some with strike-slip earthquakes, in what might evolve into a transform boundary. Given that the lake's surface lies today about 112 m below sea level, the depressed (minus ≈190 m below sea level) lake's bottom area may be considered the equivalent of the "nodal deep" in slow-slip oceanic transforms. The chemistry of the lake is compatible with the water having originated from hydrothermal liquids that had reacted with evaporites and basalts, rather than residual from evaporation of sea water. Bottom sediments include calcitic grains, halite and gypsum, as well as ostracod and diatom tests. The lake's level appears to have dropped by over 10 m during the last ≈50 years, continuing a drying up trend of the last few thousand years, after a "wet" stage 9,800 and 7,800 years before present when according to Gasse (1973) Lake Afrera covered an area several times larger than at present. This "wet" stage corresponds to an early Holocene warm-humid climate that prevailed in Saharan and Sub Saharan Africa. Lake Abhé, located roughly 250 km south of Afrera, shows similar climate-driven oscillations of its level.

Ethiopian Central Rift Valley basin hydrologic modelling using HEC-HMS and ArcSWAT

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Pascual-Ferrer, Jordi; Candela, Lucila; Pérez-Foguet, Agustí

2013-04-01

An Integrated Water Resources Management (IWRM) shall be applied to achieve a sustainable development, to increase population incomes without affecting lives of those who are highly dependent on the environment. First step should be to understand water dynamics at basin level, starting by modeling the basin water resources. For model implementation, a large number of data and parameters are required, but those are not always available, especially in some developing countries where different sources may have different data, there is lack of information on data collection, etc. The Ethiopian Central Rift Valley (CRV) is an endorheic basin covering an area of approximately 10,000 km2. For the period 1996-2005, the average annual volume of rainfall accounted for 9.1 Mm3, and evapotranspiration for 8 Mm3 (Jansen et al., 2007). From the environmental point of view, basin ecosystems are endangered due to human activities. Also, poverty is widespread all over the basin, with population mainly living from agriculture on a subsistence economy. Hence, there is an urgent need to set an IWRM, but datasets required for water dynamics simulation are not too reliable. In order to reduce uncertainty of numerical simulation, two semi-distributed open software hydrologic models were implemented: HEC-HMS and ArcSWAT. HEC-HMS was developed by the United States Army Corps of Engineers (USACoE) Hydrologic Engineering Center (HEC) to run precipitation-runoff simulations for a variety of applications in dendritic watershed systems. ArcSWAT includes the SWAT (Soil and Water Assessment Tool, Arnold et al., 1998) model developed for the USDA Agricultural Research Service into ArcGIS (ESRI®). SWAT was developed to assess the impact of land management practices on large complex watersheds with varying soils, land use and management conditions over long periods of time (Neitsch et al., 2005). According to this, ArcSWAT would be the best option for IWRM implementation in the basin. However

The Cenozoic western Svalbard margin: sediment geometry and sedimentary processes in an area of ultraslow oceanic spreading

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Amundsen, Ingrid Marie Hasle; Blinova, Maria; Hjelstuen, Berit Oline; Mjelde, Rolf; Haflidason, Haflidi

2011-12-01

The northeastern high-latitude North Atlantic is characterised by the Bellsund and Isfjorden fans on the continental slope off west Svalbard, the asymmetrical ultraslow Knipovich spreading ridge and a 1,000 m deep rift valley. Recently collected multichannel seismic profiles and bathymetric records now provide a more complete picture of sedimentary processes and depositional environments within this region. Both downslope and alongslope sedimentary processes are identified in the study area. Turbidity currents and deposition of glacigenic debris flows are the dominating downslope processes, whereas mass failures, which are a common process on glaciated margins, appear to have been less significant. The slide debrite observed on the Bellsund Fan is most likely related to a 2.5-1.7 Ma old failure on the northwestern Barents Sea margin. The seismic records further reveal that alongslope current processes played a major role in shaping the sediment packages in the study area. Within the Knipovich rift valley and at the western rift flank accumulations as thick as 950-1,000 m are deposited. We note that oceanic basement is locally exposed within the rift valley, and that seismostratigraphic relationships indicate that fault activity along the eastern rift flank lasted until at least as recently as 1.5 Ma. A purely hemipelagic origin of the sediments in the rift valley and on the western rift flank is unlikely. We suggest that these sediments, partly, have been sourced from the western Svalbard—northwestern Barents Sea margin and into the Knipovich Ridge rift valley before continuous spreading and tectonic activity caused the sediments to be transported out of the valley and westward.

Data-driven modeling to assess receptivity for Rift Valley Fever virus.

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Christopher M Barker

2013-11-01

Full Text Available Rift Valley Fever virus (RVFV is an enzootic virus that causes extensive morbidity and mortality in domestic ruminants in Africa, and it has shown the potential to invade other areas such as the Arabian Peninsula. Here, we develop methods for linking mathematical models to real-world data that could be used for continent-scale risk assessment given adequate data on local host and vector populations. We have applied the methods to a well-studied agricultural region of California with [Formula: see text]1 million dairy cattle, abundant and competent mosquito vectors, and a permissive climate that has enabled consistent transmission of West Nile virus and historically other arboviruses. Our results suggest that RVFV outbreaks could occur from February-November, but would progress slowly during winter-early spring or early fall and be limited spatially to areas with early increases in vector abundance. Risk was greatest in summer, when the areas at risk broadened to include most of the dairy farms in the study region, indicating the potential for considerable economic losses if an introduction were to occur. To assess the threat that RVFV poses to North America, including what-if scenarios for introduction and control strategies, models such as this one should be an integral part of the process; however, modeling must be paralleled by efforts to address the numerous remaining gaps in data and knowledge for this system.

Holocene evolution of a drowned melt-water valley in the Danish Wadden Sea

DEFF Research Database (Denmark)

Pedersen, Jørn Bjarke Torp; Svinth, Steffen; Bartholdy, Jesper

2009-01-01

Cores from the salt marshes along the drowned melt-water valley of river Varde Å in the Danish Wadden Sea have been dated and analysed (litho- and biostratigraphically) to reconstruct the Holocene geomorphologic evolution and relative sea level history of the area. The analysed cores cover...... the total post-glacial transgression, and the reconstructed sea level curve represents the first unbroken curve of this kind from the Danish Wadden Sea, including all phases from the time where sea level first reached the Pleistocene substrate of the area. The sea level has been rising from - 12 m below...... the present level at c. 8400 cal yr BP, interrupted by two minor drops of sea level rise, and the Holocene sequence consists in most places of clay atop...

The formation of graben morphology in the Dead Sea Fault, and its implications

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Ben-Avraham, Zvi; Katsman, Regina

2015-09-01

The Dead Sea Fault (DSF) is a 1000 km long continental transform. It forms a narrow and elongated valley with uplifted shoulders showing an east-west asymmetry, which is not common in other continental transforms. This topography may have strongly affected the course of human history. Several papers addressed the geomorphology of the DSF, but there is still no consensus with respect to the dominant mechanism of its formation. Our thermomechanical modeling demonstrates that existence of a transform prior to the rifting predefined high strain softening on the faults in the strong upper crust and created a precursor weak zone localizing deformations in the subsequent transtensional period. Together with a slow rate of extension over the Arabian plate, they controlled a narrow asymmetric morphology of the fault. This rift pattern was enhanced by a fast deposition of evaporites from the Sedom Lagoon, which occupied the rift depression for a short time period.

Predicting distribution of Aedes aegypti and Culex pipiens complex, potential vectors of Rift Valley fever virus in relation to disease epidemics in East Africa

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Clement Nyamunura Mweya

2013-10-01

Full Text Available Background: The East African region has experienced several Rift Valley fever (RVF outbreaks since the 1930s. The objective of this study was to identify distributions of potential disease vectors in relation to disease epidemics. Understanding disease vector potential distributions is a major concern for disease transmission dynamics. Methods: Diverse ecological niche modelling techniques have been developed for this purpose: we present a maximum entropy (Maxent approach for estimating distributions of potential RVF vectors in un-sampled areas in East Africa. We modelled the distribution of two species of mosquitoes (Aedes aegypti and Culex pipiens complex responsible for potential maintenance and amplification of the virus, respectively. Predicted distributions of environmentally suitable areas in East Africa were based on the presence-only occurrence data derived from our entomological study in Ngorongoro District in northern Tanzania. Results: Our model predicted potential suitable areas with high success rates of 90.9% for A. aegypti and 91.6% for C. pipiens complex. Model performance was statistically significantly better than random for both species. Most suitable sites for the two vectors were predicted in central and northwestern Tanzania with previous disease epidemics. Other important risk areas include western Lake Victoria, northern parts of Lake Malawi, and the Rift Valley region of Kenya. Conclusion: Findings from this study show distributions of vectors had biological and epidemiological significance in relation to disease outbreak hotspots, and hence provide guidance for the selection of sampling areas for RVF vectors during inter-epidemic periods.

Predicting distribution of Aedes aegypti and Culex pipiens complex, potential vectors of Rift Valley fever virus in relation to disease epidemics in East Africa.

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Mweya, Clement Nyamunura; Kimera, Sharadhuli Iddi; Kija, John Bukombe; Mboera, Leonard E G

2013-01-01

The East African region has experienced several Rift Valley fever (RVF) outbreaks since the 1930s. The objective of this study was to identify distributions of potential disease vectors in relation to disease epidemics. Understanding disease vector potential distributions is a major concern for disease transmission dynamics. DIVERSE ECOLOGICAL NICHE MODELLING TECHNIQUES HAVE BEEN DEVELOPED FOR THIS PURPOSE: we present a maximum entropy (Maxent) approach for estimating distributions of potential RVF vectors in un-sampled areas in East Africa. We modelled the distribution of two species of mosquitoes (Aedes aegypti and Culex pipiens complex) responsible for potential maintenance and amplification of the virus, respectively. Predicted distributions of environmentally suitable areas in East Africa were based on the presence-only occurrence data derived from our entomological study in Ngorongoro District in northern Tanzania. Our model predicted potential suitable areas with high success rates of 90.9% for A. aegypti and 91.6% for C. pipiens complex. Model performance was statistically significantly better than random for both species. Most suitable sites for the two vectors were predicted in central and northwestern Tanzania with previous disease epidemics. Other important risk areas include western Lake Victoria, northern parts of Lake Malawi, and the Rift Valley region of Kenya. Findings from this study show distributions of vectors had biological and epidemiological significance in relation to disease outbreak hotspots, and hence provide guidance for the selection of sampling areas for RVF vectors during inter-epidemic periods.

Innate Immune Response to Rift Valley Fever Virus in Goats

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Nfon, Charles K.; Marszal, Peter; Zhang, Shunzhen; Weingartl, Hana M.

2012-01-01

Rift Valley fever (RVF), a re-emerging mosquito-borne disease of ruminants and man, was endemic in Africa but spread to Saudi Arabia and Yemen, meaning it could spread even further. Little is known about innate and cell-mediated immunity to RVF virus (RVFV) in ruminants, which is knowledge required for adequate vaccine trials. We therefore studied these aspects in experimentally infected goats. We also compared RVFV grown in an insect cell-line and that grown in a mammalian cell-line for differences in the course of infection. Goats developed viremia one day post infection (DPI), which lasted three to four days and some goats had transient fever coinciding with peak viremia. Up to 4% of peripheral blood mononuclear cells (PBMCs) were positive for RVFV. Monocytes and dendritic cells in PBMCs declined possibly from being directly infected with virus as suggested by in vitro exposure. Infected goats produced serum IFN-γ, IL-12 and other proinflammatory cytokines but not IFN-α. Despite the lack of IFN-α, innate immunity via the IL-12 to IFN-γ circuit possibly contributed to early protection against RVFV since neutralising antibodies were detected after viremia had cleared. The course of infection with insect cell-derived RVFV (IN-RVFV) appeared to be different from mammalian cell-derived RVFV (MAM-RVFV), with the former attaining peak viremia faster, inducing fever and profoundly affecting specific immune cell subpopulations. This indicated possible differences in infections of ruminants acquired from mosquito bites relative to those due to contact with infectious material from other animals. These differences need to be considered when testing RVF vaccines in laboratory settings. PMID:22545170

Sublacustrine river valley in the shelf zone of the Black Sea parallel to the Bulgarian coast

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Preisinger, A.; Aslanian, S.; Beigelbeck, R.; Heinitz, W.-D.

2009-04-01

The considered sublacustrine river valley is situated in the shelf zone of the Black Sea. It runs in parallel to the Bulgarian coast, was formed in the time period of the Younger Dryas (Preisinger et al., 2005), and features an inclination of about 0.5 m/km. An about 200 km long sediment wall separates the approximately 10 km broad river valley from the outside shelf zone. This wall was generated during the Older Dryas until the beginning of the Younger Dryas. Its shape was formed by transportation of water and sediment from the Strait of Kerch by a circulating rim current in the Black Sea and water as well as sediment flow of the Danube in direction to the Bosporus. New investigations of the sediments of this river valley were performed by utilizing a Sediment Echo Sounder (SES 2000). This Echo Sounder is a parametric sub-bottom profiler enabling a high resolution sub-bottom analyses. It is capable of penetrating sea beds up to more than 50 m of water depth. The received echo data are real-time processed. The signal amplitudes are valuated in context to a logarithmic scale and graphically visualized by means of a colorized echogram utilizing false colours ranging from red for a high to blue representing a low signal (W.-D. Heinitz et al., 1998). The highest signal (red) is given by the acoustic impedance of the boundary between sea water and river sediment. The echograms of the river valley depict spatially isolated (red) high-signal peaks, which are periodically repeated in vertical direction between the sediment surface and the bottom of the valley. The number of these high-signal parts increase with an increasing valley depth. Studying of the distribution of these peaks allows to draw conclusions regarding the content and composition of the sediment. This prediction of the sediment composition obtained by means of the SES 2000 was successfully verified by analyzing a gravity core taken near Nos Maslen (at 44 m water depth) with a particular focus on the water

Neutralizing antibodies against flaviviruses, Babanki virus, and Rift Valley fever virus in Ugandan bats.

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Kading, Rebekah C; Kityo, Robert M; Mossel, Eric C; Borland, Erin M; Nakayiki, Teddie; Nalikka, Betty; Nyakarahuka, Luke; Ledermann, Jeremy P; Panella, Nicholas A; Gilbert, Amy T; Crabtree, Mary B; Peterhans, Julian Kerbis; Towner, Jonathan S; Amman, Brian R; Sealy, Tara K; Nichol, Stuart T; Powers, Ann M; Lutwama, Julius J; Miller, Barry R

2018-01-01

Introduction: A number of arboviruses have previously been isolated from naturally-infected East African bats, however the role of bats in arbovirus maintenance is poorly understood. The aim of this study was to investigate the exposure history of Ugandan bats to a panel of arboviruses. Materials and methods: Insectivorous and fruit bats were captured from multiple locations throughout Uganda during 2009 and 2011-2013. All serum samples were tested for neutralizing antibodies against West Nile virus (WNV), yellow fever virus (YFV), dengue 2 virus (DENV-2), Zika virus (ZIKV), Babanki virus (BBKV), and Rift Valley fever virus (RVFV) by plaque reduction neutralization test (PRNT). Sera from up to 626 bats were screened for antibodies against each virus. Results and Discussion:  Key findings include the presence of neutralizing antibodies against RVFV in 5/52 (9.6%) of little epauletted fruit bats ( Epomophorus labiatus ) captured from Kawuku and 3/54 (5.6%) Egyptian rousette bats from Kasokero cave. Antibodies reactive to flaviviruses were widespread across bat taxa and sampling locations. Conclusion: The data presented demonstrate the widespread exposure of bats in Uganda to arboviruses, and highlight particular virus-bat associations that warrant further investigation.

Inter-epidemic transmission of Rift Valley fever in livestock in the Kilombero River Valley, Tanzania: a cross-sectional survey.

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Robert D Sumaye

Full Text Available BACKGROUND: In recent years, evidence of Rift Valley fever (RVF transmission during inter-epidemic periods in parts of Africa has increasingly been reported. The inter-epidemic transmissions generally pass undetected where there is no surveillance in the livestock or human populations. We studied the presence of and the determinants for inter-epidemic RVF transmission in an area experiencing annual flooding in southern Tanzania. METHODOLOGY: A cross-sectional sero-survey was conducted in randomly selected cattle, sheep and goats in the Kilombero river valley from May to August 2011, approximately four years after the 2006/07 RVF outbreak in Tanzania. The exposure status to RVF virus (RVFV was determined using two commercial ELISA kits, detecting IgM and IgG antibodies in serum. Information about determinants was obtained through structured interviews with herd owners. FINDINGS: An overall seroprevalence of 11.3% (n = 1680 was recorded; 5.5% in animals born after the 2006/07 RVF outbreak and 22.7% in animals present during the outbreak. There was a linear increase in prevalence in the post-epidemic annual cohorts. Nine inhibition-ELISA positive samples were also positive for RVFV IgM antibodies indicating a recent infection. The spatial distribution of seroprevalence exhibited a few hotspots. The sex difference in seroprevalence in animals born after the previous epidemic was not significant (6.1% vs. 4.6% for females and males respectively, p = 0.158 whereas it was significant in animals present during the outbreak (26.0% vs. 7.8% for females and males respectively, p15 km from the flood plain were more likely to have antibodies than those living <5 km (OR 1.92; 95% CI 1.04-3.56. Species, breed, herd composition, grazing practices and altitude were not associated with seropositivity. CONCLUSION: These findings indicate post-epidemic transmission of RVFV in the study area. The linear increase in seroprevalence in the post-epidemic annual cohorts

An unexpected recurrent transmission of Rift Valley fever virus in cattle in a temperate and mountainous area of Madagascar.

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Veronique Chevalier

2011-12-01

Full Text Available Rift Valley fever is an acute, zoonotic viral disease of domestic ruminants, caused by a phlebovirus (Bunyaviridae family. A large outbreak occurred in Madagascar in 2008-2009. The goal of the present study was to evaluate the point prevalence of antibodies against Rift Valley Fever Virus (RVFV in cattle in the Anjozorobe district, located in the wet and temperate highland region of Madagascar and yet heavily affected by the disease, and analyse environmental and trade factors potentially linked to RVFV transmission. A serological study was performed in 2009 in 894 bovines. For each bovine, the following variables were recorded: age, location of the night pen, minimum distance from the pen to the nearest water point and the forest, nearest water point type, and herd replacement practices. The serological data were analyzed using a generalized linear mixed model. The overall anti-RVFV IgG seroprevalence rate was 28% [CI95% 25-31]. Age was statistically linked to prevalence (p = 10(-4, being consistent with a recurrent RVFV circulation. Distance from the night pen to the nearest water point was a protective factor (p = 5.10(-3, which would be compatible with a substantial part of the virus transmission being carried out by nocturnal mosquito vectors. However, water point type did not influence the risk of infection: several mosquito species are probably involved. Cattle belonging to owners who purchase animals to renew the herd were significantly more likely to have seroconverted than others (p = 0.04: cattle trade may contribute to the introduction of the virus in this area. The minimum distance of the night pen to the forest was not linked to the prevalence. This is the first evidence of a recurrent transmission of RVFV in such an ecosystem that associates a wet, temperate climate, high altitude, paddy fields, and vicinity to a dense rain forest. Persistence mechanisms need to be further investigated.

Rift Valley fever: current challenges and future prospects

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Himeidan YE

2016-03-01

Full Text Available Yousif E Himeidan Vector Control Unit, Africa Technical Research Centre, Vector Health International, Arusha, Tanzania Abstract: Rift Valley fever (RVF is a zoonotic, mosquito-borne viral disease that affects human health and causes significant losses in the livestock industry. Recent outbreaks have led to severe human infections with high mortality rates. There are many challenges to applying effective preventive and control measures, including weak infrastructure of health facilities, lack of capacity and support systems for field logistics and communication, access to global expert organizations, and insufficient information on the epidemiological and reservoir status of the RVF virus. The health systems in East African countries are underdeveloped, with gaps in adaptability to new, more accurate and rapid techniques, and well-trained staff that affect their capacity to monitor and evaluate the disease. Surveillance and response systems are inadequate in providing accurate information in a timely manner for decision making to deal with the scope of interrupting the disease transmission by applying mass animal vaccination, and other preventive measures at the early stage of an outbreak. The historical vaccines are unsuitable for use in newborn and gestating livestock, and the recent ones require a booster and annual revaccination. Future live-attenuated RVF vaccines should possess lower safety concerns regardless of the physiologic state of the animal, and provide rapid and long-term immunity after a single dose of vaccination. In the absence of an effective vaccination program, prevention and control measures must be immediately undertaken after an alert is generated. These measures include enforcing and adapting standard protocols for animal trade and movement, extensive vector control, safe disposal of infected animals, and modification of human–animal contact behavior. Directing control efforts on farmers and workers who deal with

Commercial helium reserves, continental rifting and volcanism

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Ballentine, C. J.; Barry, P. H.; Hillegonds, D.; Fontijn, K.; Bluett, J.; Abraham-James, T.; Danabalan, D.; Gluyas, J.; Brennwald, M. S.; Pluess, B.; Seneshens, D.; Sherwood Lollar, B.

2017-12-01

Helium has many industrial applications, but notably provides the unique cooling medium for superconducting magnets in medical MRI scanners and high energy beam lines. In 2013 the global supply chainfailed to meet demand causing significant concern - the `Liquid Helium Crisis' [1]. The 2017 closure of Quatar borders, a major helium supplier, is likely to further disrupt helium supply, and accentuates the urgent need to diversify supply. Helium is found in very few natural gas reservoirs that have focused 4He produced by the dispersed decay (a-particle) of U and Th in the crust. We show here, using the example of the Rukwa section of the Tanzanian East African Rift, how continental rifting and local volcanism provides the combination of processes required to generate helium reserves. The ancient continental crust provides the source of 4He. Rifting and associated magmatism provides the tectonic and thermal mechanism to mobilise deep fluid circulation, focusing flow to the near surface along major basement faults. Helium-rich springs in the Tanzanian Great Rift Valley were first identified in the 1950's[2]. The isotopic compositions and major element chemistry of the gases from springs and seeps are consistent with their release from the crystalline basement during rifting [3]. Within the Rukwa Rift Valley, helium seeps occur in the vicinity of trapping structures that have the potential to store significant reserves of helium [3]. Soil gas surveys over 6 prospective trapping structures (1m depth, n=1486) show helium anomalies in 5 out of the 6 at levels similar to those observed over a known helium-rich gas reservoir at 1200m depth (7% He - Harley Dome, Utah). Detailed macroseep gas compositions collected over two days (n=17) at one site allows us to distinguish shallow gas contributions and shows the deep gas to contain between 8-10% helium, significantly increasing resource estimates based on uncorrected values (1.8-4.2%)[2,3]. The remainder of the deep gas is

Salinization and dilution history of ground water discharging into the Sea of Galilee, the Dead Sea Transform, Israel

International Nuclear Information System (INIS)

Bergelson, G.; Nativ, R.; Bein, A.

1999-01-01

The mechanism governing salinization of ground water discharging into the Sea of Galilee in Israel has been the subject of debate for several decades. Because the lake provides 25% of the water consumed annually in Israel, correct identification of the salt sources is essential for the establishment of suitable water-management strategies for the lake and the ground water in the surrounding aquifers. Existing salinization models were evaluated in light of available and newly acquired data including general chemistry, and O, H, C and Cl isotopes. Based on the chemical and isotopic observations, the proposed salt source is an ancient, intensively evaporated brine (21- to 33-fold seawater) which percolated through the valley formations from a lake which had formed in the Rift Valley following seawater intrusion during the late Miocene. Low Na:Cl and high Br:Cl values support the extensive evaporation, whereas high Ca:Cl and low Mg:Cl values indicate the impact of dolomitization of the carbonate host rock on the residual solution. Based on radiocarbon and other isotope data, the dilution of the original brine occurred in two stages: the first took place similar30andpuncsp; omitted000 a ago by slightly evaporated fresh-to-brackish lake water to form the Sea of Galilee Brine. The second dilution phase is associated with the current hydrological regime as the Sea of Galilee Brine migrates upward along the Rift faults and mixes with the actively circulating fresh ground water to form the saline springs. The spatially variable chemical and isotopic features of the saline springs suggest not only differential dilution by fresh meteoric water, but also differential percolation timing of the original brine into the tectonically disconnected blocks, registering different evaporation stages in the original brine. Consequently, various operations to reduce the brine contribution to the lake may be differentially effective in the various areas. (Copyright (c) 1999 Elsevier Science

Contrasting neogene denudation histories of different structural regions in the transantarctic mountains rift flank constrained by cosmogenic isotope measurements

NARCIS (Netherlands)

Wateren, F.M. van der; Dunai, T.J.; Balen, R.T. van; Klas, W.; Verbers, A.L.L.M.; Passchier, S.; Herpers, U.

1999-01-01

Separate regions within the Transantarctic Mountains, the uplifted flank of the West Antarctic rift system, appear to have distinct Neogene histories of glaciation and valley downcutting. Incision of deep glacial outlet valleys occurred at different times throughout central and northern Victoria

Early-to-middle Holocene sea-level fluctuations, coastal progradation and the Neolithic occupations in Yaojiang valley of southern Hangzhou bay, eastern China

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Liu, Y.; Sun, Q.; Fan, D.; Chen, Z.

2017-12-01

The formation of Holocene coast in eastern China provided material base for the development of Neolithic civilizations. The coastal Yaojiang valley of south Hangzhou bay was one of the examples where the well-known Neolithic Hemudu Culture (HC) of Eastern China initiated. Here, we studied the early-to-middle Holocene environment changes in relation to sea-level fluctuations on the basis of a serial of sediment cores based on a set of new Accelerator Mass Spectrometry radiocarbon (AMS 14C) chronology. The result indicated that relative sea-level rose rapidly in the Yaojiang valley at the early Holocene, reaching its maximum at ca. 8000-7800 cal yr BP and then decelerated at ca. 7800-7500 cal yr BP. The alluvial plain in Yaojiang valley began to form at the foothills first and then grew towards the valley center accompanying with the sea-level stabilization after ca. 7500 cal yr BP. This progressive progradation of alluvial plain would attract the early arrivals of foragers to dwell at the foothills to engaging in rice farming after ca.7000 cal yr BP and starting the epic Hemudu Culture. The HC people then move down to the valley center as more land became available thanks to sediment aggregation and progradation. The rise and development of HC were closely associated with the sea-level induced landscape changes in Yaojiang valley at the early-middle Holocene, and the unstable hydraulic condition in the valley after 5000 cal yr BP could be accountable for the cultural termination.

Rifting-to-drifting transition of the South China Sea: Moho reflection characteristics in continental-ocean transition zone

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Wen, Y.; Li, C.

2017-12-01

Dispute remains on the process of continental rifting to subsequent seafloor spreading in the South China Sea (SCS). Several crust-scale multi-channel seismic reflection profiles acquired in the continent-ocean transition zone (COT) of the SCS provide a detailed overview of Moho and deep crustal reflectors and give key information on rifting-to-drifting transition of the area. Moho has strong but discontinuous seismic reflection in COT. These discontinuities are mainly located in the landward side of continent-ocean boundary (COB), and may own to upwelling of lower crustal materials during initial continental extension, leading to numerous volcanic edifices and volcanic ridges. The continental crust in COT shows discontinuous Moho reflections at 11-8.5 s in two-way travel time (twtt), and thins from 18-20.5 km under the uppermost slope to 6-7 km under the lower slope, assuming an average crustal velocity of 6.0 km/s. The oceanic crust has Moho reflections of moderate to high continuity mostly at 1.8-2.2 s twtt below the top of the igneous basement, which means that the crustal thickness excluding sediment layer in COT is 5.4-6.6 km. Subhorizontal Moho reflections are often abruptly interrupted by large seaward dipping normal faults in southern COT but are more continuous compared with the fluctuant and very discontinuous Moho reflections in northern COT. The thickness of thinned continental crust (4.2-4.8 km) is smaller than that of oceanic crust (5.4-6.0 km) near southern COB, indicating that the continental crust has experienced a long period of rifting before seafloor spreading started. The smaller width of northern COT (0-40 km) than in southern COT (0-60 km), and thinner continental crust in southern COT, all indicate that the continental margin rifting and extension was asymmetric. The COT width in the SCS is narrower than that found in other magma-poor continental margins, indicating a swift transition from the final stage of rifting to the inception of

Tectonic inheritance in the development of the Kivu - north Tanganyika rift segment of the East African Rift System: role of pre-existing structures of Precambrian to early Palaeozoic origin.

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Delvaux, Damien; Fiama Bondo, Silvanos; Ganza Bamulezi, Gloire

2017-04-01

The present architecture of the junction between the Kivu rift basin and the north Tanganyika rift basin is that of a typical accommodation zone trough the Ruzizi depression. However, this structure appeared only late in the development of the Western branch of the East African Rift System and is the result of a strong control by pre-existing structures of Precambrian to early Palaeozoic origin. In the frame of a seismic hazard assessment of the Kivu rift region, we (Delvaux et al., 2016) constructed homogeneous geological, structural and neotectonic maps cross the five countries of this region, mapped the pre-rift, early rift and Late Quaternary faults and compiled the existing knowledge on thermal springs (assumed to be diagnostic of current tectonic activity along faults). We also produced also a new catalogue of historical and instrumental seismicity and defined the seismotectonic characteristics (stress field, depth of faulting) using published focal mechanism data. Rifting in this region started at about 11 Ma by initial doming and extensive fissural basaltic volcanism along normal faults sub-parallel to the axis of the future rift valley, as a consequence of the divergence between the Nubia and the Victoria plate. In a later stage, starting around 8-7 Ma, extension localized along a series of major border faults individualizing the subsiding tectonic basins from the uplifting rift shoulders, while lava evolved towards alkali basaltic composition until 2.6 Ma. During this stage, initial Kivu rift valley was extending linearly in a SSW direction, much further than its the actual termination at Bukavu, into the Mwenga-Kamituga graben, up to Namoya. The SW extremity of this graben was linked via a long oblique transfer zone to the central part of Lake Tanganyika, itself reactivating an older ductile-brittle shear zone. In the late Quaternary-early Holocene, volcanism migrated towards the center of the basin, with the development of the Virunga volcanic massif

Spatial, seasonal and climatic predictive models of Rift Valley fever disease across Africa.

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Redding, David W; Tiedt, Sonia; Lo Iacono, Gianni; Bett, Bernard; Jones, Kate E

2017-07-19

Understanding the emergence and subsequent spread of human infectious diseases is a critical global challenge, especially for high-impact zoonotic and vector-borne diseases. Global climate and land-use change are likely to alter host and vector distributions, but understanding the impact of these changes on the burden of infectious diseases is difficult. Here, we use a Bayesian spatial model to investigate environmental drivers of one of the most important diseases in Africa, Rift Valley fever (RVF). The model uses a hierarchical approach to determine how environmental drivers vary both spatially and seasonally, and incorporates the effects of key climatic oscillations, to produce a continental risk map of RVF in livestock (as a proxy for human RVF risk). We find RVF risk has a distinct seasonal spatial pattern influenced by climatic variation, with the majority of cases occurring in South Africa and Kenya in the first half of an El Niño year. Irrigation, rainfall and human population density were the main drivers of RVF cases, independent of seasonal, climatic or spatial variation. By accounting more subtly for the patterns in RVF data, we better determine the importance of underlying environmental drivers, and also make space- and time-sensitive predictions to better direct future surveillance resources.This article is part of the themed issue 'One Health for a changing world: zoonoses, ecosystems and human well-being'. © 2017 The Authors.

Relationship of climate, geography, and geology to the incidence of Rift Valley fever in Kenya during the 2006-2007 outbreak.

Science.gov (United States)

Hightower, Allen; Kinkade, Carl; Nguku, Patrick M; Anyangu, Amwayi; Mutonga, David; Omolo, Jared; Njenga, M Kariuki; Feikin, Daniel R; Schnabel, David; Ombok, Maurice; Breiman, Robert F

2012-02-01

We estimated Rift Valley fever (RVF) incidence as a function of geological, geographical, and climatological factors during the 2006-2007 RVF epidemic in Kenya. Location information was obtained for 214 of 340 (63%) confirmed and probable RVF cases that occurred during an outbreak from November 1, 2006 to February 28, 2007. Locations with subtypes of solonetz, calcisols, solonchaks, and planosols soil types were highly associated with RVF occurrence during the outbreak period. Increased rainfall and higher greenness measures before the outbreak were associated with increased risk. RVF was more likely to occur on plains, in densely bushed areas, at lower elevations, and in the Somalia acacia ecological zone. Cases occurred in three spatial temporal clusters that differed by the date of associated rainfall, soil type, and land usage.

Development of a novel, single-cycle replicable rift valley Fever vaccine.

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Shin Murakami

2014-03-01

Full Text Available Rift Valley fever virus (RVFV (genus Phlebovirus, family Bunyaviridae is an arbovirus that causes severe disease in humans and livestock in sub-Saharan African countries. Although the MP-12 strain of RVFV is a live attenuated vaccine candidate, neuroinvasiveness and neurovirulence of MP-12 in mice may be a concern when vaccinating certain individuals, especially those that are immunocompromised. We have developed a novel, single-cycle replicable MP-12 (scMP-12, which carries an L RNA, M RNA mutant encoding a mutant envelope protein lacking an endoplasmic reticulum retrieval signal and defective for membrane fusion function, and S RNA encoding N protein and green fluorescent protein. The scMP-12 underwent efficient amplification, then formed plaques and retained the introduced mutation after serial passages in a cell line stably expressing viral envelope proteins. However, inoculation of the scMP-12 into naïve cells resulted in a single round of viral replication, and production of low levels of noninfectious virus-like particles. Intracranial inoculation of scMP-12 into suckling mice did not cause clinical signs or death, a finding which demonstrated that the scMP-12 lacked neurovirulence. Mice immunized with a single dose of scMP-12 produced neutralizing antibodies, whose titers were higher than in mice immunized with replicon particles carrying L RNA and S RNA encoding N protein and green fluorescent protein. Moreover, 90% of the scMP-12-immunized mice were protected from wild-type RVFV challenge by efficiently suppressing viremia and replication of the challenge virus in the liver and the spleen. These data demonstrated that scMP-12 is a safe and immunogenic RVFV vaccine candidate.

Rift Valley fever virus infections in Egyptian cattle and their prevention.

Science.gov (United States)

Mroz, C; Gwida, M; El-Ashker, M; Ziegler, U; Homeier-Bachmann, T; Eiden, M; Groschup, M H

2017-12-01

Rift Valley fever virus (RVFV) causes consistently severe outbreaks with high public health impacts and economic losses in livestock in many African countries and has also been introduced to Saudi Arabia and Yemen. Egypt with its four large outbreaks in the last 40 years represents the northernmost endemic area of RVFV. The purpose of this study was to provide an insight into the current anti-RVFV antibody status in immunized as well as non-immunized dairy cattle from the Nile Delta of Egypt. During 2013-2015, a total of 4,167 dairy cattle from four governorates including Dakahlia, Damietta, Gharbia and Port Said were investigated. All cattle were born after 2007 and therewith after the last reported Egyptian RVFV outbreak in 2003. The samples derived from vaccinated animals from 26 different dairy farms as well as non-immunized cattle from 27 different smallholding flocks. All samples were examined following a three-part analysis including a commercially available competition ELISA, an in-house immunofluorescence assay and a virus neutralization test. Additionally, a subset of samples was analysed for acute infections using IgM ELISA and real-time reverse transcriptase PCR. The results indicated that the RVFV is still circulating in Egypt as about 10% of the non-immunized animals exhibited RVFV-specific antibodies. Surprisingly, the antibody prevalence in immunized animals was not significantly higher than that in non-vaccinated animals which points out the need for further evaluation of the vaccination programme. Due to the substantial role of livestock in the amplification and transmission of RVFV, further recurrent monitoring of the antibody prevalence in susceptible species is highly warranted. © 2017 Blackwell Verlag GmbH.

The Plio-Pleistocene Evolution of the Indian Ocean Monsoonal System: Evidence from the Arabian Sea and East Africa

Science.gov (United States)

Wilson, K. E.; Maslin, M. A.; Mackay, A. W.; Leng, M. J.; Kingston, J.; Deino, A.

2011-12-01

It is important to identify the teleconnections between high latitude forcing and tropical monsoonal circulation in order to understand climate change in East Africa during the Plio-Pleistocene. Here we present a record of aeolian dust transport to the Arabian Sea between approximately 2.9 and 2.3 million years ago (Ma), constructed from the high-resolution XRF scanning of sediment cores from ODP Sites 721 and 722. Variations in the delivery of aeolian dust to the Arabian Sea, reflected in normalised flux of titanium, show that monsoonal circulation prior to 2.6 Ma, and after 2.5 Ma, was highly variable and primarily driven by orbitally-forced changes in tropical summer insolation, strongly modulated by the 400,000 year cycle of orbital eccentricity. This is confirmed by the presence of lakes in the East African Rift Valley during key eccentricity maxima. The dust record is coupled with the analysis of a well-dated series of diatomite units from the Baringo-Bogoria Basin which document the rhythmic cycling of large, precessionally-driven freshwater lakes which periodically occupied the Central Kenyan Rift Valley between 2.7 and 2.58 Ma. Analysis of one of these lake sequences using stable oxygen isotope measurements of diatom silica, combined with the XRF analysis of whole-sample geochemistry, reveals that the deep lake phase was characterised by fluctuations in rainfall and lake depth over cycles lasting, on average, 1,400 years. The presence of these millennial-scale fluctuations is confirmed by evidence of abrupt climate cycles in the oceanic dust record from the Arabian Sea.

Emerging vector-borne diseases in dromedaries in Tunisia: West Nile, bluetongue, epizootic haemorrhagic disease and Rift Valley fever

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Thameur B. Hassine

2017-03-01

Full Text Available A total of 118 sera were collected during 2016 from two groups of dromedaries from Kebili and Medenine governorates in the south of Tunisia. The aim of this study was to provide the first serological investigation of four emerging vector-borne diseases in two groups of dromedaries in Tunisia. Sera were tested by ELISA and serum neutralisation test to identify West Nile virus (WNV, bluetongue virus (BTV, epizootic haemorrhagic disease virus (EHDV and Rift Valley fever virus (RVFV. In the first group, the seroprevalence for BTV was 4.6%, while in the second group, it was 25.8% for WNV and 9.7% for BTV. Only serotype 1 was detected for BTV in the two groups. No evidence for circulation of RVF and EHD viruses was revealed. Results indicated that dromedaries can be infected with BTV and WNV, suggesting that this species might play a significant role in the epizootiology of these viral diseases in Tunisia and neighbouring countries.

Emerging vector-borne diseases in dromedaries in Tunisia: West Nile, bluetongue, epizootic haemorrhagic disease and Rift Valley fever.

Science.gov (United States)

Hassine, Thameur B; Amdouni, Jihane; Monaco, Federica; Savini, Giovanni; Sghaier, Soufien; Selimen, Imed B; Chandoul, Walid; Hamida, Khaled B; Hammami, Salah

2017-03-31

A total of 118 sera were collected during 2016 from two groups of dromedaries from Kebili and Medenine governorates in the south of Tunisia. The aim of this study was to provide the first serological investigation of four emerging vector-borne diseases in two groups of dromedaries in Tunisia. Sera were tested by ELISA and serum neutralisation test to identify West Nile virus (WNV), bluetongue virus (BTV), epizootic haemorrhagic disease virus (EHDV) and Rift Valley fever virus (RVFV). In the first group, the seroprevalence for BTV was 4.6%, while in the second group, it was 25.8% for WNV and 9.7% for BTV. Only serotype 1 was detected for BTV in the two groups. No evidence for circulation of RVF and EHD viruses was revealed. Results indicated that dromedaries can be infected with BTV and WNV, suggesting that this species might play a significant role in the epizootiology of these viral diseases in Tunisia and neighbouring countries.

Presence of viral RNA and proteins in exosomes from the cellular clones resistant to Rift Valley Fever Virus infection.

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Noor eAhsan

2016-02-01

Full Text Available Rift Valley Fever Virus (RVFV is a RNA virus that belongs to the genus Phlebovirus, family Bunyaviridae. It infects humans and livestock and causes Rift Valley fever. RVFV is considered an agricultural pathogen by the USDA, as it can cause up to 100% abortion in cattle and extensive death of newborns. In addition, it is designated as Category A pathogen by the CDC and the NIAID. In some human cases of RVFV infection, the virus causes fever, ocular damage, liver damage, hemorrhagic fever, and death. There are currently limited options for vaccine candidates, which include the MP-12 and clone 13 versions of RVFV. Viral infections often deregulate multiple cellular pathways that contribute to replication and host pathology. We have previously shown that latent HIV-1 and HTLV-1 infected cells secrete exosomes that contain short viral RNAs, limited number of genomic RNAs, and viral proteins. These exosomes largely target neighboring cells and activate the NF-кB pathway, leading to cell proliferation and overall better viral replication. In this manuscript, we studied the effects of exosome formation from RVFV infected cells and their function on recipient cells. We initially infected cells, isolated resistant clones, and further purified using dilution cloning. We then characterized these cells as resistant to new RVFV infection, but sensitive to other viral infections, including Venezuelan Equine Encephalitis Virus (VEEV. These clones contained normal markers (i.e. CD63 for exosomes and were able to activate the TLR pathway in recipient reporter cells. Interestingly, the exosome rich preparations, much like their host cell, contained viral RNA (L, M, and S genome. The RNAs were detected using qRT-PCR in both parental and exosomal preparations as well as in CD63 immunoprecipitates. Viral proteins such as N and a modified form of NSs were present in some of these exosomes. Finally, treatment of recipient cells (T- cells and monocytic cells showed

Attenuation of pathogenic Rift Valley fever virus strain through the chimeric S-segment encoding sandfly fever phlebovirus NSs or a dominant-negative PKR.

Science.gov (United States)

Nishiyama, Shoko; Slack, Olga A L; Lokugamage, Nandadeva; Hill, Terence E; Juelich, Terry L; Zhang, Lihong; Smith, Jennifer K; Perez, David; Gong, Bin; Freiberg, Alexander N; Ikegami, Tetsuro

2016-11-16

Rift Valley fever is a mosquito-borne zoonotic disease affecting ruminants and humans. Rift Valley fever virus (RVFV: family Bunyaviridae, genus Phlebovirus) causes abortions and fetal malformations in ruminants, and hemorrhagic fever, encephalitis, or retinitis in humans. The live-attenuated MP-12 vaccine is conditionally licensed for veterinary use in the US. However, this vaccine lacks a marker for the differentiation of vaccinated from infected animals (DIVA). NSs gene is dispensable for RVFV replication, and thus, rMP-12 strains lacking NSs gene is applicable to monitor vaccinated animals. However, the immunogenicity of MP-12 lacking NSs was not as high as parental MP-12. Thus, chimeric MP-12 strains encoding NSs from either Toscana virus (TOSV), sandfly fever Sicilian virus (SFSV) or Punta Toro virus Adames strain (PTA) were characterized previously. Although chimeric MP-12 strains are highly immunogenic, the attenuation through the S-segment remains unknown. Using pathogenic ZH501 strain, we aimed to demonstrate the attenuation of ZH501 strain through chimeric S-segment encoding either the NSs of TOSV, SFSV, PTA, or Punta Toro virus Balliet strain (PTB). In addition, we characterized rZH501 encoding a human dominant-negative PKR (PKRΔE7), which also enhances the immunogenicity of MP-12. Study done on mice revealed that attenuation of rZH501 occurred through the S-segment encoding either PKRΔE7 or SFSV NSs. However, rZH501 encoding either TOSV, PTA, or PTB NSs in the S-segment uniformly caused lethal encephalitis. Our results indicated that the S-segments encoding PKRΔE7 or SFSV NSs are attenuated and thus applicable toward next generation MP-12 vaccine candidates that encode a DIVA marker.

Land Use-Land Cover dynamics of Huluka watershed, Central Rift Valley, Ethiopia

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Hagos Gebreslassie

2014-12-01

Full Text Available Land Use-Land Cover (LULC dynamic has of human kind age and is one of the phenomenons which interweave the socio economic and environmental issues in Ethiopia. Huluka watershed is one of the watersheds in Central Rift Valley of Ethiopia which drains to Lake Langano. Few decades ago the stated watershed was covered with dense acacia forest. But, nowadays like other part of Ethiopia, it is experiencing complex dynamics of LULC. The aim of this research was thus to evaluate the LULC dynamics seen in between 1973–2009. This was achieved through collecting qualitative and quantitative data using Geographic Information System (GIS and Remote Sensing (RS technique. Field observations, discussion with elders were also employed to validate results from remotely sensed data. Based on the result, eight major dynamic LULC classes were identified from the watershed. Of these LULC classes, only cultivated and open lands had shown continuous and progressive expansion mainly at the expense of grass, shrub and forest lands. The 25% and 0% of cultivated and open land of the watershed in 1973 expanded to 84% and 4% in 2009 respectively while the 29%, 18% and 22% of grass, shrub and forest land of the watershed in 1973 degraded to 3.5%, 4% and 1.5% in 2009 respectively. As a result, land units which had been used for pastoralist before 1973 were identified under mixed agricultural system after 2000. In the end, this study came with a recommendation of an intervention of concerned body to stop the rapid degradation of vegetation on the watershed.

Off-axis volcano-tectonic activity during continental rifting: Insights from the transversal Goba-Bonga lineament, Main Ethiopian Rift (East Africa)

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Corti, Giacomo; Sani, Federico; Agostini, Samuele; Philippon, Melody; Sokoutis, Dimitrios; Willingshofer, Ernst

2018-03-01

The Main Ethiopian Rift, East Africa, is characterized by the presence of major, enigmatic structures which strike approximately orthogonal to the trend of the rift valley. These structures are marked by important deformation and magmatic activity in an off-axis position in the plateaus surrounding the rift. In this study, we present new structural data based on a remote and field analysis, complemented with analogue modelling experiments, and new geochemical analysis of volcanic rocks sampled in different portions of one of these transversal structures: the Goba-Bonga volcano-tectonic lineament (GBVL). This integrated analysis shows that the GBVL is associated with roughly E-W-trending prominent volcano-tectonic activity affecting the western plateau. Within the rift floor, the approximately E-W alignment of Awasa and Corbetti calderas likely represent expressions of the GBVL. Conversely, no tectonic or volcanic features of similar (E-W) orientation have been recognized on the eastern plateau. Analogue modelling suggests that the volcano-tectonic features of the GBVL have probably been controlled by the presence of a roughly E-W striking pre-existing discontinuity beneath the western plateau, which did not extend beneath the eastern plateau. Geochemical analysis supports this interpretation and indicates that, although magmas have the same sub-lithospheric mantle source, limited differences in magma evolution displayed by products found along the GBVL may be ascribed to the different tectonic framework to the west, to the east, and in the axial zone of the rift. These results support the importance of the heterogeneous nature of the lithosphere and the spatial variations of its structure in controlling the architecture of continental rifts and the distribution of the related volcano-tectonic activity.

Response of the Apodi-Mossoró estuary-incised valley system (NE Brazil to sea-level fluctuations

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Helenice Vital

2010-01-01

Full Text Available This study focuses on the Quaternary sea level changes in the Apodi-Mossoró Estuary and adjacent shelf, Northeastern Brazil, based on the analysis of high-resolution seismic profiles, integrated with echosounder, SRTM and satellite image data. We use these data to develop a relative stratigraphy. An incised-valley extending from the Apodi-Mossoró Estuary onto the shelf dominates the investigated area. In very shallow waters (down to 10 m depth the channel lies mainly in a NW-SE direction, changing to NE-SW in waters below10 m, in the form of a J-shaped valley. The southern flank of the shallow channel presents an abrupt morphology, probably determined by a residual scarp due to neotectonic reactivation of a pre-existing fault. This incised-valley can be correlated with a former river valley formed during the late Pleistocene fall in sea-level. The base-level change related to this drop in sea level can be regionally expressed on seismic lines as a laterally-continuous stratigraphic surface named Horizon I, interpreted as representing the sub-aerial exposure of the continental shelf. Many incised valleys were excavated on this exposed shelf, including that of the Apodi-Mossoró Estuary and its incised valley system. This incised valley has lain buried since the Holocene transgression. The Holocene sediments present sub-horizontal layers, or they have filled the incised valley with oblique features.Este estudo utiliza a integração de dados sísmicos de alta resolução, batimétricos, SRTM e imagens de satélite para desenvolvimento da estratigrafia relativa visando entender as variações do nível do mar durante o Quaternário no estuário do rio Apodi-Mossoró e plataforma adjacente, nordeste do Brasil. A principal feição identificada foi um canal submerso, na plataforma interna, parcialmente preenchido, provavelmente relacionado com o sistema de vales incisos formado durante o rebaixamento do nível do mar no Pleistoceno. O canal

Potential for North American mosquitoes (Diptera: Culicidae) to transmit rift valley fever virus.

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Turell, Michael J; Wilson, William C; Bennett, Kristine E

2010-09-01

To determine which arthropods should be targeted for control should Rift Valley fever virus (RVFV) be detected in North America, we evaluated Culex erraticus (Dyar and Knab), Culex erythrothorax Dyar, Culex nigripalpus Theobald, Culex pipiens L., Culex quinquefasciatus Say, Culex tarsalis Coquillett, Aedes dorsalis (Wiedemann), Aedes vexans (Meigen), Anopheles quadrimaculatus Say, and Culicoides sonorensis Wirth and Jones from the western, midwestern, and southern United States for their ability to transmit RVFV. Female mosquitoes were allowed to feed on adult hamsters inoculated with RVFV, after which engorged mosquitoes were incubated for 7-21 d at 260C, then allowed to refeed on susceptible hamsters, and tested to determine infection, dissemination, and transmission rates. Other specimens were inoculated intrathoracically, held for 7 d, and then allowed to feed on a susceptible hamster to check for a salivary gland barrier. When exposed to hamsters with viremias > or =10(8.8) plaque-forming units/ml blood, Cx. tarsalis transmitted RVFV efficiently (infection rate = 93%, dissemination rate = 56%, and estimated transmission rate = 52%). In contrast, when exposed to the same virus dose, none of the other species tested transmitted RVFV efficiently. Estimated transmission rates for Cx. erythrothorax, Cx. pipiens, Cx. erraticus, and Ae. dorsalis were 10, 8, 4, and 2%, respectively, and for the remaining species were feeding preference, longevity, and foraging behavior should be considered when determining the potential role that these species could play in RVFV transmission.

A fusion-inhibiting peptide against Rift Valley fever virus inhibits multiple, diverse viruses.

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Jeffrey W Koehler

Full Text Available For enveloped viruses, fusion of the viral envelope with a cellular membrane is critical for a productive infection to occur. This fusion process is mediated by at least three classes of fusion proteins (Class I, II, and III based on the protein sequence and structure. For Rift Valley fever virus (RVFV, the glycoprotein Gc (Class II fusion protein mediates this fusion event following entry into the endocytic pathway, allowing the viral genome access to the cell cytoplasm. Here, we show that peptides analogous to the RVFV Gc stem region inhibited RVFV infectivity in cell culture by inhibiting the fusion process. Further, we show that infectivity can be inhibited for diverse, unrelated RNA viruses that have Class I (Ebola virus, Class II (Andes virus, or Class III (vesicular stomatitis virus fusion proteins using this single peptide. Our findings are consistent with an inhibition mechanism similar to that proposed for stem peptide fusion inhibitors of dengue virus in which the RVFV inhibitory peptide first binds to both the virion and cell membranes, allowing it to traffic with the virus into the endocytic pathway. Upon acidification and rearrangement of Gc, the peptide is then able to specifically bind to Gc and prevent fusion of the viral and endocytic membranes, thus inhibiting viral infection. These results could provide novel insights into conserved features among the three classes of viral fusion proteins and offer direction for the future development of broadly active fusion inhibitors.

Environmental change and Rift Valley fever in eastern Africa: projecting beyond HEALTHY FUTURES

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David Taylor

2016-03-01

Full Text Available Outbreaks of Rift Valley fever (RVF, a relatively recently emerged zoonosis endemic to large parts of sub-Saharan Africa that has the potential to spread beyond the continent, have profound health and socio-economic impacts, particularly in communities where resilience is already low. Here output from a new, dynamic disease model [the Liverpool RVF (LRVF model], driven by downscaled, bias-corrected climate change data from an ensemble of global circulation models from the Inter-Sectoral Impact Model Intercomparison Project run according to two radiative forcing scenarios [representative concentration pathway (RCP4.5 and RCP8.5], is combined with results of a spatial assessment of social vulnerability to the disease in eastern Africa. The combined approach allowed for analyses of spatial and temporal variations in the risk of RVF to the end of the current century. Results for both scenarios highlight the high-risk of future RVF outbreaks, including in parts of eastern Africa to date unaffected by the disease. The results also highlight the risk of spread from/to countries adjacent to the study area, and possibly farther afield, and the value of considering the geography of future projections of disease risk. Based on the results, there is a clear need to remain vigilant and to invest not only in surveillance and early warning systems, but also in addressing the socio-economic factors that underpin social vulnerability in order to mitigate, effectively, future impacts.

NSs Virulence Factor of Rift Valley Fever Virus Engages the F-Box Proteins FBXW11 and β-TRCP1 To Degrade the Antiviral Protein Kinase PKR.

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Kainulainen, Markus; Lau, Simone; Samuel, Charles E; Hornung, Veit; Weber, Friedemann

2016-07-01

Rift Valley fever virus (RVFV, family Bunyaviridae, genus Phlebovirus) is a relevant pathogen of both humans and livestock in Africa. The nonstructural protein NSs is a major virulence factor known to suppress the type I interferon (IFN) response by inhibiting host cell transcription and by proteasomal degradation of a major antiviral IFN effector, the translation-inhibiting protein kinase PKR. Here, we identified components of the modular SCF (Skp1, Cul1, F-box protein)-type E3 ubiquitin ligases as mediators of PKR destruction by NSs. Small interfering RNAs (siRNAs) against the conserved SCF subunit Skp1 protected PKR from NSs-mediated degradation. Consequently, RVFV replication was severely reduced in Skp1-depleted cells when PKR was present. SCF complexes have a variable F-box protein subunit that determines substrate specificity for ubiquitination. We performed an siRNA screen for all (about 70) human F-box proteins and found FBXW11 to be involved in PKR degradation. The partial stabilization of PKR by FBXW11 depletion upregulated PKR autophosphorylation and phosphorylation of the PKR substrate eIF2α and caused a shutoff of host cell protein synthesis in RVFV-infected cells. To maximally protect PKR from the action of NSs, knockdown of structurally and functionally related FBXW1 (also known as β-TRCP1), in addition to FBXW11 deletion, was necessary. Consequently, NSs was found to interact with both FBXW11 and β-TRCP1. Thus, NSs eliminates the antiviral kinase PKR by recruitment of SCF-type E3 ubiquitin ligases containing FBXW11 and β-TRCP1 as substrate recognition subunits. This antagonism of PKR by NSs is essential for efficient RVFV replication in mammalian cells. Rift Valley fever virus is a pathogen of humans and animals that has the potential to spread from Africa and the Arabian Peninsula to other regions. A major virulence mechanism is the proteasomal degradation of the antiviral kinase PKR by the viral protein NSs. Here, we demonstrate that NSs

Driving force of organic fertilizer use in Central Rift Valley of Ethiopia: Independent double hurdle approach

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Terefe Aemro T.

2016-01-01

Full Text Available The objective of this study was to identify the important factors that influence both adoption and level of use of organic fertilizer among smallholder farmers in the Central Rift Valley of Ethiopia using a primary data collected from 161 sample respondents. An independent double hurdle model was used to address the objectives of the study on the assumption that adoption and level of organic fertilizer use by are two independent decisions influenced by different factors. Empirical estimates of the first hurdle reveals that literacy status of the head, livestock holding, frequency of extension contact, distance to market and slope of the plot are statistically significant decision variables that affect the probability of adopting organic fertilizer. Meanwhile, estimates of the second hurdle revealed that, the extent of use of organic fertilizer was determined by livestock holding, access to credit distance to the market and slope of plot. This indicates that factors that affect adoption are not necessarily the same as those that influence intensity. Therefore, it is important to consider both stages in evaluating strategies aimed at promoting the adoption and use of organic fertilizer.

The East African rift system

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Chorowicz, Jean

2005-10-01

This overview paper considers the East African rift system (EARS) as an intra-continental ridge system, comprising an axial rift. It describes the structural organization in three branches, the overall morphology, lithospheric cross-sections, the morphotectonics, the main tectonic features—with emphasis on the tension fractures—and volcanism in its relationships with the tectonics. The most characteristic features in the EARS are narrow elongate zones of thinned continental lithosphere related to asthenospheric intrusions in the upper mantle. This hidden part of the rift structure is expressed on the surface by thermal uplift of the rift shoulders. The graben valleys and basins are organized over a major failure in the lithospheric mantle, and in the crust comprise a major border fault, linked in depth to a low angle detachment fault, inducing asymmetric roll-over pattern, eventually accompanied by smaller normal faulting and tilted blocks. Considering the kinematics, divergent movements caused the continent to split along lines of preexisting lithospheric weaknesses marked by ancient tectonic patterns that focus the extensional strain. The hypothesis favored here is SE-ward relative divergent drifting of a not yet well individualized Somalian plate, a model in agreement with the existence of NW-striking transform and transfer zones. The East African rift system comprises a unique succession of graben basins linked and segmented by intracontinental transform, transfer and accommodation zones. In an attempt to make a point on the rift system evolution through time and space, it is clear that the role of plume impacts is determinant. The main phenomenon is formation of domes related to plume effect, weakening the lithosphere and, long after, failure inducing focused upper mantle thinning, asthenospheric intrusion and related thermal uplift of shoulders. The plume that had formed first at around 30 Ma was not in the Afar but likely in Lake Tana region (Ethiopia

Dike intrusions during rifting episodes obey scaling relationships similar to earthquakes

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L., Passarelli; E., Rivalta; A., Shuler

2014-01-01

As continental rifts evolve towards mid-ocean ridges, strain is accommodated by repeated episodes of faulting and magmatism. Discrete rifting episodes have been observed along two subaerial divergent plate boundaries, the Krafla segment of the Northern Volcanic Rift Zone in Iceland and the Manda-Hararo segment of the Red Sea Rift in Ethiopia. In both cases, the initial and largest dike intrusion was followed by a series of smaller intrusions. By performing a statistical analysis of these rifting episodes, we demonstrate that dike intrusions obey scaling relationships similar to earthquakes. We find that the dimensions of dike intrusions obey a power law analogous to the Gutenberg-Richter relation, and the long-term release of geodetic moment is governed by a relationship consistent with the Omori law. Due to the effects of magma supply, the timing of secondary dike intrusions differs from that of the aftershocks. This work provides evidence of self-similarity in the rifting process. PMID:24469260

Delineating the Drainage Structure and Sources of Groundwater Flux for Lake Basaka, Central Rift Valley Region of Ethiopia

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Megersa Olumana Dinka

2017-11-01

Full Text Available As opposed to most of the other closed basin type rift valley lakes in Ethiopia, Lake Basaka is found to be expanding at an alarming rate. Different studies indicated that the expansion of the lake is challenging the socio-economics and environment of the region significantly. This study result and previous reports indicated that the lake’s expansion is mostly due to the increased groundwater (GW flux to the lake. GW flux accounts for about 56% of the total inflow in recent periods (post 2000 and is found to be the dominant factor for the hydrodynamics and existence of the lake. The analysis of the drainage network for the area indicates the existence of a huge recharge area on the western and upstream side of the catchment. This catchment has no surface outlet; hence most of the incoming surface runoff recharges the GW system. The recharge area is the main source of GW flux to the lake. In addition to this, the likely sources/causes of GW flux to the lake could be: (i an increase of GW recharge following the establishment of irrigation schemes in the region; (ii subsurface inflow from far away due to rift system influence, and (iii lake neotectonism. Overall, the lake’s expansion has damaging effect to the region, owing to its poor water quality; hence the identification of the real causes of GW flux and mitigation measures are very important for sustainable lake management. Therefore a comprehensive and detailed investigation of the parameters related to GW flux and the interaction of the lake with the GW system of the area is highly recommended.

Infection and transmission of Rift Valley fever viruses lacking the NSs and/or NSm genes in mosquitoes: potential role for NSm in mosquito infection.

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Mary B Crabtree

Full Text Available BACKGROUND: Rift Valley fever virus is an arthropod-borne human and animal pathogen responsible for large outbreaks of acute and febrile illness throughout Africa and the Arabian Peninsula. Reverse genetics technology has been used to develop deletion mutants of the virus that lack the NSs and/or NSm virulence genes and have been shown to be stable, immunogenic and protective against Rift Valley fever virus infection in animals. We assessed the potential for these deletion mutant viruses to infect and be transmitted by Aedes mosquitoes, which are the principal vectors for maintenance of the virus in nature and emergence of virus initiating disease outbreaks, and by Culex mosquitoes which are important amplification vectors. METHODOLOGY AND PRINCIPAL FINDINGS: Aedes aegypti and Culex quinquefasciatus mosquitoes were fed bloodmeals containing the deletion mutant viruses. Two weeks post-exposure mosquitoes were assayed for infection, dissemination, and transmission. In Ae. aegypti, infection and transmission rates of the NSs deletion virus were similar to wild type virus while dissemination rates were significantly reduced. Infection and dissemination rates for the NSm deletion virus were lower compared to wild type. Virus lacking both NSs and NSm failed to infect Ae. aegypti. In Cx. quinquefasciatus, infection rates for viruses lacking NSm or both NSs and NSm were lower than for wild type virus. CONCLUSIONS/SIGNIFICANCE: In both species, deletion of NSm or both NSs and NSm reduced the infection and transmission potential of the virus. Deletion of both NSs and NSm resulted in the highest level of attenuation of virus replication. Deletion of NSm alone was sufficient to nearly abolish infection in Aedes aegypti mosquitoes, indicating an important role for this protein. The double deleted viruses represent an ideal vaccine profile in terms of environmental containment due to lack of ability to efficiently infect and be transmitted by mosquitoes.

Infection and transmission of Rift Valley fever viruses lacking the NSs and/or NSm genes in mosquitoes: potential role for NSm in mosquito infection.

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Crabtree, Mary B; Kent Crockett, Rebekah J; Bird, Brian H; Nichol, Stuart T; Erickson, Bobbie Rae; Biggerstaff, Brad J; Horiuchi, Kalanthe; Miller, Barry R

2012-01-01

Rift Valley fever virus is an arthropod-borne human and animal pathogen responsible for large outbreaks of acute and febrile illness throughout Africa and the Arabian Peninsula. Reverse genetics technology has been used to develop deletion mutants of the virus that lack the NSs and/or NSm virulence genes and have been shown to be stable, immunogenic and protective against Rift Valley fever virus infection in animals. We assessed the potential for these deletion mutant viruses to infect and be transmitted by Aedes mosquitoes, which are the principal vectors for maintenance of the virus in nature and emergence of virus initiating disease outbreaks, and by Culex mosquitoes which are important amplification vectors. Aedes aegypti and Culex quinquefasciatus mosquitoes were fed bloodmeals containing the deletion mutant viruses. Two weeks post-exposure mosquitoes were assayed for infection, dissemination, and transmission. In Ae. aegypti, infection and transmission rates of the NSs deletion virus were similar to wild type virus while dissemination rates were significantly reduced. Infection and dissemination rates for the NSm deletion virus were lower compared to wild type. Virus lacking both NSs and NSm failed to infect Ae. aegypti. In Cx. quinquefasciatus, infection rates for viruses lacking NSm or both NSs and NSm were lower than for wild type virus. In both species, deletion of NSm or both NSs and NSm reduced the infection and transmission potential of the virus. Deletion of both NSs and NSm resulted in the highest level of attenuation of virus replication. Deletion of NSm alone was sufficient to nearly abolish infection in Aedes aegypti mosquitoes, indicating an important role for this protein. The double deleted viruses represent an ideal vaccine profile in terms of environmental containment due to lack of ability to efficiently infect and be transmitted by mosquitoes.

The Nile valley of Egypt: A major active graben that magnifies seismic waves

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EI-Sayed, A.; Vaccari, F.; Panza, G.F.

2002-08-01

The Nile valley and the Nile delta are part of the active rift that is probably connected with the Red Sea tectonism. This zone is characterized by small to moderate size earthquakes that have caused extremely severe damage to recent and historical constructions. The most vulnerable area along the Nile valley is the one of Cairo-Faiyoum. Small local and large distant earthquakes could be a source of huge socio-economic damage in this area. The loose soft alluvial sediments of the Nile Canyon are the main factors behind this potential damage because they may greatly amplify the ground motion, as demonstrated by strong ground motion modelling. The largest amplification is generally concentrated along the edges of the graben and occurs at frequencies between 1 Hz and 2 Hz. This may explain the huge damage caused by distant earthquakes during recent and historical times. The distribution of intensity values during the events of 1926 and 1992 is well correlated with the modelled spatial distribution of the spectral amplification. (author)

Characterization of Rift Valley fever virus MP-12 strain encoding NSs of Punta Toro virus or sandfly fever Sicilian virus.

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Lihoradova, Olga A; Indran, Sabarish V; Kalveram, Birte; Lokugamage, Nandadeva; Head, Jennifer A; Gong, Bin; Tigabu, Bersabeh; Juelich, Terry L; Freiberg, Alexander N; Ikegami, Tetsuro

2013-01-01

Rift Valley fever virus (RVFV; genus Phlebovirus, family Bunyaviridae) is a mosquito-borne zoonotic pathogen which can cause hemorrhagic fever, neurological disorders or blindness in humans, and a high rate of abortion in ruminants. MP-12 strain, a live-attenuated candidate vaccine, is attenuated in the M- and L-segments, but the S-segment retains the virulent phenotype. MP-12 was manufactured as an Investigational New Drug vaccine by using MRC-5 cells and encodes a functional NSs gene, the major virulence factor of RVFV which 1) induces a shutoff of the host transcription, 2) inhibits interferon (IFN)-β promoter activation, and 3) promotes the degradation of dsRNA-dependent protein kinase (PKR). MP-12 lacks a marker for differentiation of infected from vaccinated animals (DIVA). Although MP-12 lacking NSs works for DIVA, it does not replicate efficiently in type-I IFN-competent MRC-5 cells, while the use of type-I IFN-incompetent cells may negatively affect its genetic stability. To generate modified MP-12 vaccine candidates encoding a DIVA marker, while still replicating efficiently in MRC-5 cells, we generated recombinant MP-12 encoding Punta Toro virus Adames strain NSs (rMP12-PTNSs) or Sandfly fever Sicilian virus NSs (rMP12-SFSNSs) in place of MP-12 NSs. We have demonstrated that those recombinant MP-12 viruses inhibit IFN-β mRNA synthesis, yet do not promote the degradation of PKR. The rMP12-PTNSs, but not rMP12-SFSNSs, replicated more efficiently than recombinant MP-12 lacking NSs in MRC-5 cells. Mice vaccinated with rMP12-PTNSs or rMP12-SFSNSs induced neutralizing antibodies at a level equivalent to those vaccinated with MP-12, and were efficiently protected from wild-type RVFV challenge. The rMP12-PTNSs and rMP12-SFSNSs did not induce antibodies cross-reactive to anti-RVFV NSs antibody and are therefore applicable to DIVA. Thus, rMP12-PTNSs is highly efficacious, replicates efficiently in MRC-5 cells, and encodes a DIVA marker, all of which are

Magma-poor vs. magma-rich continental rifting and breakup in the Labrador Sea

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Gouiza, M.; Paton, D.

2017-12-01

Magma-poor and magma-rich rifted margins show distinct structural and stratigraphic geometries during the rift to breakup period. In magma-poor margins, crustal stretching is accommodated mainly by brittle faulting and the formation of wide rift basins shaped by numerous graben and half-graben structures. Continental breakup and oceanic crust accretion are often preceded by a localised phase of (hyper-) extension where the upper mantle is embrittled, serpentinized, and exhumed to the surface. In magma-rich margins, the rift basin is narrow and extension is accompanied by a large magmatic supply. Continental breakup and oceanic crust accretion is preceded by the emplacement of a thick volcanic crust juxtaposing and underplating a moderately thinned continental crust. Both magma-poor and magma-rich rifting occur in response to lithospheric extension but the driving forces and processes are believed to be different. In the former extension is assumed to be driven by plate boundary forces, while in the latter extension is supposed to be controlled by sublithospheric mantle dynamics. However, this view fails in explaining observations from many Atlantic conjugate margins where magma-poor and magma-rich segments alternate in a relatively abrupt fashion. This is the case of the Labrador margin where the northern segment shows major magmatic supply during most of the syn-rift phase which culminate in the emplacement of a thick volcanic crust in the transitional domain along with high density bodies underplating the thinned continental crust; while the southern segment is characterized mainly by brittle extension, mantle seprentinization and exhumation prior to continental breakup. In this work, we use seismic and potential field data to describe the crustal and structural architectures of the Labrador margin, and investigate the tectonic and mechanical processes of rifting that may have controlled the magmatic supply in the different segments of the margin.

The Red Sea and Gulf of Aden Basins

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Bosworth, William; Huchon, Philippe; McClay, Ken

2005-10-01

We here summarize the evolution of the greater Red Sea-Gulf of Aden rift system, which includes the Gulfs of Suez and Aqaba, the Red Sea and Gulf of Aden marine basins and their continental margins, and the Afar region. Plume related basaltic trap volcanism began in Ethiopia, NE Sudan (Derudeb), and SW Yemen at ˜31 Ma, followed by rhyolitic volcanism at ˜30 Ma. Volcanism thereafter spread northward to Harrats Sirat, Hadan, Ishara-Khirsat, and Ar Rahat in western Saudi Arabia. This early magmatism occurred without significant extension, and continued to ˜25 Ma. Much of the Red Sea and Gulf of Aden region was at or near sea level at this time. Starting between ˜29.9 and 28.7 Ma, marine syn-tectonic sediments were deposited on continental crust in the central Gulf of Aden. At the same time the Horn of Africa became emergent. By ˜27.5-23.8 Ma a small rift basin was forming in the Eritrean Red Sea. At approximately the same time (˜25 Ma), extension and rifting commenced within Afar itself. At ˜24 Ma, a new phase of volcanism, principally basaltic dikes but also layered gabbro and granophyre bodies, appeared nearly synchronously throughout the entire Red Sea, from Afar and Yemen to northern Egypt. This second phase of magmatism was accompanied in the Red Sea by strong rift-normal extension and deposition of syn-tectonic sediments, mostly of marine and marginal marine affinity. Sedimentary facies were laterally heterogeneous, being comprised of inter-fingering siliciclastics, evaporite, and carbonate. Throughout the Red Sea, the principal phase of rift shoulder uplift and rapid syn-rift subsidence followed shortly thereafter at ˜20 Ma. Water depths increased dramatically and sedimentation changed to predominantly Globigerina-rich marl and deepwater limestone. Within a few million years of its initiation in the mid-Oligocene the Gulf of Aden continental rift linked the Owen fracture zone (oceanic crust) with the Afar plume. The principal driving force for extension

Phanerozoic Rifting Phases And Mineral Deposits

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Hassaan, Mahmoud

2016-04-01

In North Africa occur Mediterranean and Red Sea metallogenic provinces. In each province distribute 47 iron- manganese- barite and lead-zinc deposits with tectonic-structural control. The author presents in this paper aspects of position of these deposits in the two provinces with Phanerozoic rifting . The Mediterranean Province belongs to two epochs, Hercynian and Alpine. The Hercynian Epoch manganese deposits in only Moroccoa- Algeria belong to Paleozoic tectonic zones and Proterozoic volcanics. The Alpine Epoch iron-manganese deposits are of post-orogenic exhalative-sedimentary origin. Manganese deposits in southern Morocco occur in Kabil-Rief quartz-chalcedony veins controlled by faults in andesitic sheets and in bedded pelitic tuffs, strata-form lenses and ore veins, in Precambrian schist and in Triassic and Cretaceous dolomites. Disseminated manganese with quartz and barite and effusive hydrothermal veins are hosted in Paleocene volcanics. Manganese deposits in Algeria are limited and unrecorded in Tunisia. Strata-form iron deposits in Atlas Heights are widespread in sub-rift zone among Jurassic sediments inter-bedding volcanic rocks. In Algeria, Group Beni-Saf iron deposits are localized along the Mediterranean coast in terrigenous and carbonate rocks of Jurassic, Cretaceous and Eocene age within faults and bedding planes. In Morocco strata-form hydrothermal lead-zinc deposits occur in contact zone of Tertiary andesite inter-bedding Cambrian shale, Lias dolomites and Eocene andesite. In both Algeria and Tunisia metasomatic Pb-Zn veins occur in Campanian - Maastrichtian carbonates, Triassic breccia, Jurassic limestone, Paleocene sandstones and limestone and Neogene conglomerates and sandstones. The Red Sea metallogenic province belongs to the Late Tertiary-Miocene times. In Wadi Araba hydrothermal iron-manganese deposits occur in Cretaceous sediments within 320°and 310 NW faults related to Tertiary basalt. Um-Bogma iron-manganese deposits are closely

Climate Influence on Emerging Risk Areas for Rift Valley Fever Epidemics in Tanzania.

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Mweya, Clement N; Mboera, Leonard E G; Kimera, Sharadhuli I

2017-07-01

Rift Valley Fever (RVF) is a climate-related arboviral infection of animals and humans. Climate is thought to represent a threat toward emerging risk areas for RVF epidemics globally. The objective of this study was to evaluate influence of climate on distribution of suitable breeding habitats for Culex pipiens complex, potential mosquito vector responsible for transmission and distribution of disease epidemics risk areas in Tanzania. We used ecological niche models to estimate potential distribution of disease risk areas based on vectors and disease co-occurrence data approach. Climatic variables for the current and future scenarios were used as model inputs. Changes in mosquito vectors' habitat suitability in relation to disease risk areas were estimated. We used partial receiver operating characteristic and the area under the curves approach to evaluate model predictive performance and significance. Habitat suitability for Cx. pipiens complex indicated broad-scale potential for change and shift in the distribution of the vectors and disease for both 2020 and 2050 climatic scenarios. Risk areas indicated more intensification in the areas surrounding Lake Victoria and northeastern part of the country through 2050 climate scenario. Models show higher probability of emerging risk areas spreading toward the western parts of Tanzania from northeastern areas and decrease in the southern part of the country. Results presented here identified sites for consideration to guide surveillance and control interventions to reduce risk of RVF disease epidemics in Tanzania. A collaborative approach is recommended to develop and adapt climate-related disease control and prevention strategies.

Crustal thickness and Moho sharpness beneath the Midcontinent rift from receiver functions

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Moikwathai Moidaki

2013-02-01

Full Text Available The Mesoproterozoic Midcontinent rift (MCR in the central US is an approximately 2000 km long, 100 km wide structure from Kansas to Michigan. During the 20-40 million years of rifting, a thick (up to 20 km layer of basaltic lava was deposited in the rift valleys. Quantifying the effects of the rifting and associated volcanic eruptions on the structure and composition of the crust and mantle beneath the MCR is important for the understanding of the evolution of continental lithosphere. In this study we measure the crustal thickness (H, and the sharpness of the Moho (R at about 24 portable and permanent stations in Iowa, Kansas, and South Dakota by stacking Pto- S converted waves (PmS and their multiples (PPmS and PSmS. Under the assumption that the crustal mean velocity in the study area is the same as the IASP91 earth model, we find a significantly thickened crust beneath the MCR of about 53 km. The crustal Vp/Vs ratios increases from about 1.80 off rift to as large as 1.95 within the rift, which corresponds to an increase of Poisson’s ratio from 0.28 to 0.32, suggesting a more mafic crust beneath the MCR. The R measurements are spatially variable and are relatively small in the vicinity of the MCR, indicating the disturbance of the original sharp Moho by the rifting and magmatic intrusion and volcanic eruption.

Immunogenicity and efficacy of a chimpanzee adenovirus-vectored Rift Valley fever vaccine in mice.

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Warimwe, George M; Lorenzo, Gema; Lopez-Gil, Elena; Reyes-Sandoval, Arturo; Cottingham, Matthew G; Spencer, Alexandra J; Collins, Katharine A; Dicks, Matthew D J; Milicic, Anita; Lall, Amar; Furze, Julie; Turner, Alison V; Hill, Adrian V S; Brun, Alejandro; Gilbert, Sarah C

2013-12-05

Rift Valley Fever (RVF) is a viral zoonosis that historically affects livestock production and human health in sub-Saharan Africa, though epizootics have also occurred in the Arabian Peninsula. Whilst an effective live-attenuated vaccine is available for livestock, there is currently no licensed human RVF vaccine. Replication-deficient chimpanzee adenovirus (ChAd) vectors are an ideal platform for development of a human RVF vaccine, given the low prevalence of neutralizing antibodies against them in the human population, and their excellent safety and immunogenicity profile in human clinical trials of vaccines against a wide range of pathogens. Here, in BALB/c mice, we evaluated the immunogenicity and efficacy of a replication-deficient chimpanzee adenovirus vector, ChAdOx1, encoding the RVF virus envelope glycoproteins, Gn and Gc, which are targets of virus neutralizing antibodies. The ChAdOx1-GnGc vaccine was assessed in comparison to a replication-deficient human adenovirus type 5 vector encoding Gn and Gc (HAdV5-GnGc), a strategy previously shown to confer protective immunity against RVF in mice. A single immunization with either of the vaccines conferred protection against RVF virus challenge eight weeks post-immunization. Both vaccines elicited RVF virus neutralizing antibody and a robust CD8+ T cell response. Together the results support further development of RVF vaccines based on replication-deficient adenovirus vectors, with ChAdOx1-GnGc being a potential candidate for use in future human clinical trials.

p53 Activation following Rift Valley fever virus infection contributes to cell death and viral production.

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Dana Austin

Full Text Available Rift Valley fever virus (RVFV is an emerging viral zoonosis that is responsible for devastating outbreaks among livestock and is capable of causing potentially fatal disease in humans. Studies have shown that upon infection, certain viruses have the capability of utilizing particular cellular signaling pathways to propagate viral infection. Activation of p53 is important for the DNA damage signaling cascade, initiation of apoptosis, cell cycle arrest and transcriptional regulation of multiple genes. The current study focuses on the role of p53 signaling in RVFV infection and viral replication. These results show an up-regulation of p53 phosphorylation at several serine sites after RVFV MP-12 infection that is highly dependent on the viral protein NSs. qRT-PCR data showed a transcriptional up-regulation of several p53 targeted genes involved in cell cycle and apoptosis regulation following RVFV infection. Cell viability assays demonstrate that loss of p53 results in less RVFV induced cell death. Furthermore, decreased viral titers in p53 null cells indicate that RVFV utilizes p53 to enhance viral production. Collectively, these experiments indicate that the p53 signaling pathway is utilized during RVFV infection to induce cell death and increase viral production.

Ecological niche modeling and land cover risk areas for rift valley fever vector, culex tritaeniorhynchus giles in Jazan, Saudi Arabia.

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Sallam, Mohamed F; Al Ahmed, Azzam M; Abdel-Dayem, Mahmoud S; Abdullah, Mohamed A R

2013-01-01

The mosquito, Culex tritaeniorhynchus Giles is a prevalent and confirmed Rift Valley Fever virus (RVFV) vector. This vector, in association with Aedimorphus arabiensis (Patton), was responsible for causing the outbreak of 2000 in Jazan Province, Saudi Arabia. Larval occurrence records and a total of 19 bioclimatic and three topographic layers imported from Worldclim Database were used to predict the larval suitable breeding habitats for this vector in Jazan Province using ArcGIS ver.10 and MaxEnt modeling program. Also, a supervised land cover classification from SPOT5 imagery was developed to assess the land cover distribution within the suitable predicted habitats. Eleven bioclimatic and slope attributes were found to be the significant predictors for this larval suitable breeding habitat. Precipitation and temperature were strong predictors of mosquito distribution. Among six land cover classes, the linear regression model (LM) indicated wet muddy substrate is significantly associated with high-very high suitable predicted habitats (R(2) = 73.7%, Presearchers.

Detection of Rift Valley Fever Virus Interepidemic Activity in Some Hotspot Areas of Kenya by Sentinel Animal Surveillance, 2009–2012

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Jacqueline Kasiiti Lichoti

2014-01-01

Full Text Available Rift Valley fever virus causes an important zoonotic disease of humans and small ruminants in Eastern Africa and is spread primarily by a mosquito vector. In this region, it occurs as epizootics that typically occur at 5–15-year intervals associated with unusual rainfall events. It has hitherto been known that the virus is maintained between outbreaks in dormant eggs of the mosquito vector and this has formed the basis of understanding of the epidemiology and control strategies of the disease. We show here that seroconversion and sporadic acute disease do occur during the interepidemic periods (IEPs in the absence of reported cases in livestock or humans. The finding indicates that previously undetected low-level virus transmission during the IEPs does occur and that epizootics may also be due to periodic expansion of mosquito vectors in the presence of both circulating virus and naïve animals.

Identification of central Kenyan Rift Valley Fever virus vector habitats with Landsat TM and evaluation of their flooding status with airborne imaging radar

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Pope, K. O.; Sheffner, E. J.; Linthicum, K. J.; Bailey, C. L.; Logan, T. M.; Kasischke, E. S.; Birney, K.; Njogu, A. R.; Roberts, C. R.

1992-01-01

Rift Valley Fever (RVF) is a mosquito-borne virus that affects livestock and humans in Africa. Landsat TM data are shown to be effective in identifying dambos, intermittently flooded areas that are potential mosquite breeding sites, in an area north of Nairobi, Kenya. Positive results were obtained from a limited test of flood detection in dambos with airborne high resolution L, C, and X band multipolarization SAR imagery. L and C bands were effective in detecting flooded dambos, but LHH was by far the best channel for discrimination between flooded and nonflooded sites in both sedge and short-grass environments. This study demonstrates the feasibility of a combined passive and active remote sensing program for monitoring the location and condition of RVF vector habitats, thus making future control of the disease more promising.

Structure and Geochemistry of the Continental-Oceanic Crust Boundary of the Red Sea and the Rifted Margin of Western Arabia

Science.gov (United States)

Dilek, Y.; Furnes, H.; Schoenberg, R.

2009-12-01

The continental-oceanic crust boundary and an incipient oceanic crust of the Red Sea opening are exposed within the Arabian plate along a narrow zone of the Tihama Asir coastal plain in SW Saudi Arabia. Dike swarms, layered gabbros, granophyres and basalts of the 22 Ma Tihama Asir (TA) continental margin ophiolite represent products of magmatic differentiation formed during the initial stages of rifting between the African and Arabian plates. Nearly 4-km-wide zone of NW-trending sheeted dikes are the first products of mafic magmatism associated with incipient oceanic crust formation following the initial continental breakup. Gabbro intrusions are composed of cpx-ol-gabbro, cpx-gabbro, and norite/troctolite, and are crosscut by fine-grained basaltic dikes. Granophyre bodies intrude the sheeted dike swarms and are locally intrusive into the gabbros. Regional Bouger gravity anomalies suggest that the Miocene mafic crust represented by the TA complex extends westward beneath the coastal plain sedimentary rocks and the main trough of the Red Sea. The TA complex marks an incipient Red Sea oceanic crust that was accreted to the NE side of the newly formed continental rift in the earliest stages of seafloor spreading. Its basaltic to trachyandesitic lavas and dikes straddle the subalkaline-mildly alkaline boundary. Incompatible trace element relationships (e.g. Zr-Ti, Zr-P) indicate two distinct populations. The REE concentrations show an overall enrichment compared to N-MORB; light REEs are enriched over the heavy ones ((La/Yb)n > 1), pointing to an E-MORB influence. Nd-isotope data show ɛNd values ranging from +4 to +8, supporting an E-MORB melt source. The relatively large variations in ɛNd values also suggest various degrees of involvement of continental crust during ascent and emplacement, or by mixing of another mantle source.

Mid-Continent Rift: Rift, LIP, or Both?

Science.gov (United States)

Stein, C. A.; Stein, S. A.; Kley, J.; Hindle, D.; Keller, G. R., Jr.

2014-12-01

North America's Midcontinent Rift (MCR) is traditionally considered to have formed by midplate extension and volcanism ~1.1 Ga that ended due to compression from the Grenville orogeny, the ~1.3 - ~0.98 Ga assembly of Amazonia (Precambrian northeast South America), Laurentia (Precambrian North America), and other continents into the supercontinent of Rodinia. We find that a more plausible scenario is that it formed as part of the rifting of Amazonia from Laurentia and became inactive once seafloor spreading was established. The MCR has aspects both of a continental rift - a segmented linear depression filled with sedimentary and igneous rocks - and a large igneous province (LIP). Comparison of areas and volumes for a range of continental LIPS shows that the MCR volcanic rocks are significantly thicker than the others. The MCR flood basalts have steeper dips and thicker overlying sediments than other continental flood basalts, and were deposited in a subsiding basin after most extension ended, indicating that they are better viewed as post-rift than syn-rift rocks. Hence we view the MCR as a LIP deposited in crust weakened by rifting, and thus first a rift and then a LIP.

Last glacial-Holocene temperatures and hydrology of the Sea of Galilee and Hula Valley from clumped isotopes in Melanopsis shells

Science.gov (United States)

Zaarur, Shikma; Affek, Hagit P.; Stein, Mordechai

2016-04-01

The carbonate clumped isotope (Δ47) thermometer was applied to fresh water snails (Melanopsis spp.) grown in the waters of the Sea of Galilee and Hula Valley, in the north of Israel. Modern shells, grown at known temperatures agree with the Δ47-T calibration of Zaarur et al. (2013). Fossil Melanopsis shells from 2 locations, Gesher Bnot Ya'aqov (at the southern tip of the Hula Valley) and the Sea of Galilee provide a temperature record for the region during the time interval of the past 20 kyrs. Glacial temperatures are ∼5 °C cooler than mid-Holocene and ∼3 °C cooler than modern, similar to other records in the region. These Δ47-derived temperatures are combined with δ18O of the shell carbonate to calculate the oxygen isotopic composition of the habitat waters. Contrary to global trends and other regional records, reconstructed δ18Owater values increase from the late glacial through the Holocene. This reversed signal reflects a decrease in the relative contribution of snowmelt to the watershed post-LGM and a transition to a more rain dominated inflow. A fairly constant difference in δ18Owater values between the Hula Valley and Sea of Galilee waters, suggests that the hydrological relationship of the two water bodies had remained constant, with the temperature changes playing only a minor role in the extent of evaporation of the Sea of Galilee relative to the Hula.

Fracture-zone tectonics at Zabargad Island, Red Sea (Egypt)

Science.gov (United States)

Marshak, Stephen; Bonatti, Enrico; Brueckner, Hannes; Paulsen, Timothy

1992-12-01

Zabargad Island, which lies along the western margin of the Red Sea rift, is a remarkable place because it provides fresh exposures of undepleted mantle peridotite. How this peridotite came to be exposed on Zabargad remains unclear. Our field mapping indicates that most of the contacts between peridotite and the adjacent bodies of Pan-African gneiss and Cretaceous(?) Zabargad Formation on the island are now high-angle brittle faults. Zabargad Formation strata have been complexly folded, partly in response to this faulting. Overall, the array of high-angle faults and associated folds on the island resembles those found in cross-rift transfer zones. We suggest, therefore, that the Zabargad fracture zone, a band of submarine escarpments on the floor of the Red Sea north of the island, crosses Zabargad Island and has actively resolved differential movement between the central Red Sea rift and the northern Red Sea rift. The final stage of uplift that brought the unusual peridotite to the earth's surface is related to shallow crustal transpression, which may have inverted an earlier transtensional regime.

Imaging rifting at the lithospheric scale in the northern East African Rift using S-to-P receiver functions

Science.gov (United States)

Lavayssiere, A.; Rychert, C.; Harmon, N.; Keir, D.; Hammond, J. O. S.; Kendall, J. M.; Leroy, S. D.; Doubre, C.

2017-12-01

The lithosphere is modified during rifting by a combination of mechanical stretching, heating and potentially partial melt. We image the crust and upper mantle discontinuity structure beneath the northern East African Rift System (EARS), a unique tectonically active continental rift exposing along strike the transition from continental rifting in the Main Ethiopian rift (MER) to incipient seafloor spreading in Afar and the Red Sea. S-to-P receiver functions from 182 stations across the northern EARS were generated from 3688 high quality waveforms using a multitaper technique and then migrated to depth using a regional velocity model. Waveform modelling of data stacked in large conversion point bins confirms the depth and strength of imaged discontinuities. We image the Moho at 29.6±4.7 km depth beneath the Ethiopian plateaux with a variability in depth that is possibly due to lower crustal intrusions. The crust is 27.3±3.9 km thick in the MER and thinner in northern Afar, 17.5±0.7 km. The model requires a 3±1.2% reduction in shear velocity with increasing depth at 68.5±1.5 km beneath the Ethiopian plateaux, consistent with the lithosphere-asthenosphere boundary (LAB). We do not resolve a LAB beneath Afar and the MER. This is likely associated with partial melt near the base of the lithosphere, reducing the velocity contrast between the melt-intruded lithosphere and the partially molten asthenosphere. We identify a 4.5±0.7% increase in velocity with depth at 91±3 km beneath the MER. This change in velocity is consistent with the onset of melting found by previous receiver functions and petrology studies. Our results provide independent constraints on the depth of melt production in the asthenosphere and suggest melt percolation through the base of the lithosphere beneath the northernmost East African rift.

Tectonostratigraphy of the Southern Part of Papua and Arafura Sea, Eastern Indonesia

Directory of Open Access Journals (Sweden)

Bhakti H. Harahap

2014-06-01

Full Text Available DOI: 10.17014/ijog.v7i3.145Sedimentary history and stratigraphy of the Papua and Arafura Sea areas, eastern Indonesia, are gained from surface geological mapping combined with published data from oil companies. Development of some sedimentary units demonstrates that the tectonism have influenced sedimentation of such units comprising a succession of Phanerozoic rocks developing in a stable continental margin. The succession underlain by Cambrian-Silurian-Devonian metamorphic rocks consists of Tuaba, Kariem, Awitagoh, and Kemum Formation, and Modio Dolomite (Pre-Rift Phase. These rocks having been intruded by Late Permian-Middle Triassic granitoids and Carboniferous granite, are unconformably overlain by Late Carboniferous to Cretaceous siliciclastic-rich units comprising Aifam Group and Tipuma Formation (syn-Rift Phase and Kembelangan Group (Mesozoic Passive Margin Post-Rift. The Aifam Group is separated by a regionally continuous boundary on its top contact from the Triassic-Early Jurassic Tipuma Formation, which filled the block-faulted rift valley subbasins of continentally deposited red beds in the breakup stage. Regionally, developed erosion surfaces of the breakup unconformity have separated these red beds from generally transgressive post-breakup deposits of the Jurassic to Cretaceous marine sediments of the Kembelangan Group. Beach to shallow marine-glauconitic sandstone and shale of the group pass upward into shelf mudstone. Relative sea level fall related to the tectonic stability of the area led to the development of Eocene to Late Miocene platform carbonates of the New Guinea Limestone Supergroup which occurred in the entire island of Papua and the southern of Arafura that overlie these non-carbonate units (Tertiary passive margin. It is separated from the siliciclastic-rich packages by the Tertiary - Pre-Tertiary boundary. The sea level fluctuation within the group was also recorded during the formation of thin, discontinuous

Identification of mutations in the M RNA of a candidate vaccine strain of Rift Valley fever virus.

Science.gov (United States)

Takehara, K; Min, M K; Battles, J K; Sugiyama, K; Emery, V C; Dalrymple, J M; Bishop, D H

1989-04-01

The M RNA species of a candidate vaccine strain of Rift Valley fever virus (RVFV ZH-548M12), derived by consecutive high level mutagenesis using 5-fluorouracil (H. Caplen, C. J. Peters, and D. H. L. Bishop, J. Gen. Virol., 66, 2271-2277, 1985), has been cloned and the cDNA sequenced. The data have been compared to those obtained for the parent virus strain RVFV ZH-548 as well as the previously published data for RVFV ZH-501 (M. S. Collett, A. F. Purchio, K. Keegan, S. Frazier, W. Hays, D. K. Anderson, M. D. Parker, C. Schmaljohn, J. Schmidt, and J. M. Dalrymple, Virology, 144, 228-245, 1985). Some eight nucleotide and three amino acid differences were identified between the M RNAs of ZH-501 and ZH-548. Between the M RNAs of ZH-548 and that of the M12 mutant there were 12 nucleotide and 7 amino acid changes. Unique to the mutant virus is a new AUG codon upstream of that which initiates the open reading frame of the RVFV M gene product (the viral glycoprotein precursor). The significance of this and other differences in the mutant RNA with regard to the derivation and potential attenuation of the candidate vaccine is discussed.

Time-transgressive tunnel valley formation indicated by infill sediment structure, North Sea - the role of glaciohydraulic supercooling

DEFF Research Database (Denmark)

Kristensen, Thomas Bojer; Piotrowski, Jan; Huuse, Mads

2008-01-01

Structure and lithology of the infill sediments from 16 subglacial buried tunnel valleys of Pleistocene age in the North Sea were analyzed using 3D seismic data and geophysical log data from five hydrocarbon exploration wells. The infill sediments are characterized by three seismic facies: Facies...

The role of signal transducer and activator of transcription 3 in Rift Valley fever virus infection

International Nuclear Information System (INIS)

Pinkham, Chelsea; An, Soyeon; Lundberg, Lindsay; Bansal, Neha; Benedict, Ashwini; Narayanan, Aarthi; Kehn-Hall, Kylene

2016-01-01

Rift Valley fever (RVF) is a zoonotic disease that can cause severe illness in humans and livestock, triggering spontaneous abortion in almost 100% of pregnant ruminants. In this study, we demonstrate that signal transducer and activator of transcription 3 (STAT3) is phosphorylated on its conserved tyrosine residue (Y705) following RVFV infection. This phosphorylation was dependent on a major virulence factor, the viral nonstructural protein NSs. Loss of STAT3 had little effect on viral replication, but rather resulted in cells being more susceptible to RVFV-induced cell death. Phosphorylated STAT3 translocated to the nucleus, coinciding with inhibition of fos, jun, and nr4a2 gene expression, and the presence of STAT3 and NSs at the nr4a2 promoter. NSs was found predominantly in the cytoplasm of STAT3 null cells, indicating that STAT3 influences NSs nuclear localization. Collectively, these data demonstrate that STAT3 functions in a pro-survival capacity through modulation of NSs localization. - Highlights: • STAT3 is phosphorylated on tyrosine residue 705 following RVFV infection. • Phosphorylation of STAT3 was dependent on the viral protein NSs. • STAT3 -/- MEFs were more susceptible to RVFV-induced cell death. • Loss of STAT3 led to an increase in pro-apoptotic gene expression. • STAT3 functions in a pro-survival capacity by modulation of NSs localization.

NSs protein of rift valley fever virus promotes posttranslational downregulation of the TFIIH subunit p62.

Science.gov (United States)

Kalveram, Birte; Lihoradova, Olga; Ikegami, Tetsuro

2011-07-01

Rift Valley fever virus (RVFV; family Bunyaviridae, genus Phlebovirus) is an important emerging pathogen of humans and ruminants. Its NSs protein has previously been identified as a major virulence factor that suppresses host defense through three distinct mechanisms: it directly inhibits beta interferon (IFN-β) promoter activity, it promotes the degradation of double-stranded RNA-dependent protein kinase (PKR), and it suppresses host transcription by disrupting the assembly of the basal transcription factor TFIIH through sequestration of its p44 subunit. Here, we report that in addition to PKR, NSs also promotes the degradation of the TFIIH subunit p62. Infection of cells with the RVFV MP-12 vaccine strain reduced p62 protein levels to below the detection limit early in the course of infection. This NSs-mediated downregulation of p62 was posttranslational, as it was unaffected by pharmacological inhibition of transcription or translation and MP-12 infection had no effect on p62 mRNA levels. Treatment of cells with proteasome inhibitors but not inhibition of lysosomal acidification or nuclear export resulted in a stabilization of p62 in the presence of NSs. Furthermore, p62 could be coprecipitated with NSs from lysates of infected cells. These data suggest that the RVFV NSs protein is able to interact with the TFIIH subunit p62 inside infected cells and promotes its degradation, which can occur directly in the nucleus.

The role of signal transducer and activator of transcription 3 in Rift Valley fever virus infection

Energy Technology Data Exchange (ETDEWEB)

Pinkham, Chelsea; An, Soyeon; Lundberg, Lindsay; Bansal, Neha; Benedict, Ashwini; Narayanan, Aarthi; Kehn-Hall, Kylene, E-mail: kkehnhal@gmu.edu

2016-09-15

Rift Valley fever (RVF) is a zoonotic disease that can cause severe illness in humans and livestock, triggering spontaneous abortion in almost 100% of pregnant ruminants. In this study, we demonstrate that signal transducer and activator of transcription 3 (STAT3) is phosphorylated on its conserved tyrosine residue (Y705) following RVFV infection. This phosphorylation was dependent on a major virulence factor, the viral nonstructural protein NSs. Loss of STAT3 had little effect on viral replication, but rather resulted in cells being more susceptible to RVFV-induced cell death. Phosphorylated STAT3 translocated to the nucleus, coinciding with inhibition of fos, jun, and nr4a2 gene expression, and the presence of STAT3 and NSs at the nr4a2 promoter. NSs was found predominantly in the cytoplasm of STAT3 null cells, indicating that STAT3 influences NSs nuclear localization. Collectively, these data demonstrate that STAT3 functions in a pro-survival capacity through modulation of NSs localization. - Highlights: • STAT3 is phosphorylated on tyrosine residue 705 following RVFV infection. • Phosphorylation of STAT3 was dependent on the viral protein NSs. • STAT3 -/- MEFs were more susceptible to RVFV-induced cell death. • Loss of STAT3 led to an increase in pro-apoptotic gene expression. • STAT3 functions in a pro-survival capacity by modulation of NSs localization.

Luminescence characteristics of quartz from the Southern Kenyan Rift Valley: Dose estimation using LM-OSL SAR

International Nuclear Information System (INIS)

Choi, J.H.; Duller, G.A.T.; Wintle, A.G.; Cheong, C.-S.

2006-01-01

Linearly modulated (LM) optically stimulated luminescence (OSL) measurements have revealed that some sedimentary quartz samples from the Kenyan Rift Valley do not have a fast OSL component, but contain a medium component and several slow components. It was impossible to recover a known dose for these samples using the conventional single-aliquot regenerative-dose (SAR) procedure. The dose-response curves and continuous wave (CW) OSL decay curves for these samples showed several undesirable properties for dating. We have compared various luminescence characteristics of these samples with other quartz samples from elsewhere in the world for which the SAR procedure has been shown to be appropriate; the latter were dominated by a fast OSL component. The characteristics include photoionisation cross-sections for each component and the relative proportions of the different components in the initial and total OSL signals. It was found that those samples that had greater than 90% of the initial 0.8 s of their OSL signal from the fast component were suitable for dating using the conventional SAR protocol. A novel method of displaying the relative contributions of the different OSL components in a ternary diagram is proposed. The thermal stability of each component was investigated using pulse-annealing experiments. We then examined the possibility of applying an LM-OSL SAR protocol to samples that have a substantial medium component

Crustal structure and rift tectonics across the Cauvery–Palar basin ...

Indian Academy of Sciences (India)

The Cauvery–Palar basin is a major peri-cratonic rift basin located along the Eastern Continental. Margin of India ..... density P(k) of a magnetized body having infinite extensions in the .... aly data must be brought down to the sea level through ...

Virulence factor NSs of rift valley fever virus recruits the F-box protein FBXO3 to degrade subunit p62 of general transcription factor TFIIH.

Science.gov (United States)

Kainulainen, Markus; Habjan, Matthias; Hubel, Philipp; Busch, Laura; Lau, Simone; Colinge, Jacques; Superti-Furga, Giulio; Pichlmair, Andreas; Weber, Friedemann

2014-03-01

The nonstructural protein NSs is the main virulence factor of Rift Valley fever virus (RVFV; family Bunyaviridae, genus Phlebovirus), a serious pathogen of livestock and humans in Africa. RVFV NSs blocks transcriptional upregulation of antiviral type I interferons (IFN) and destroys the general transcription factor TFIIH subunit p62 via the ubiquitin/proteasome pathway. Here, we identified a subunit of E3 ubiquitin ligases, F-box protein FBXO3, as a host cell interactor of NSs. Small interfering RNA (siRNA)-mediated depletion of FBXO3 rescued p62 protein levels in RVFV-infected cells and elevated IFN transcription by 1 order of magnitude. NSs interacts with the full-length FBXO3 protein as well as with a truncated isoform that lacks the C-terminal acidic and poly(R)-rich domains. These isoforms are present in both the nucleus and the cytoplasm. NSs exclusively removes the nuclear pool of full-length FBXO3, likely due to consumption during the degradation process. F-box proteins form the variable substrate recognition subunit of the so-called SCF ubiquitin ligases, which also contain the constant components Skp1, cullin 1 (or cullin 7), and Rbx1. siRNA knockdown of Skp1 also protected p62 from degradation, suggesting involvement in NSs action. However, knockdown of cullin 1, cullin 7, or Rbx1 could not rescue p62 degradation by NSs. Our data show that the enzymatic removal of p62 via the host cell factor FBXO3 is a major mechanism of IFN suppression by RVFV. Rift Valley fever virus is a serious emerging pathogen of animals and humans. Its main virulence factor, NSs, enables unhindered virus replication by suppressing the antiviral innate immune system. We identified the E3 ubiquitin ligase FBXO3 as a novel host cell interactor of NSs. NSs recruits FBXO3 to destroy the general host cell transcription factor TFIIH-p62, resulting in suppression of the transcriptional upregulation of innate immunity.

Functional analysis of Rift Valley fever virus NSs encoding a partial truncation.

Science.gov (United States)

Head, Jennifer A; Kalveram, Birte; Ikegami, Tetsuro

2012-01-01

Rift Valley fever virus (RVFV), belongs to genus Phlebovirus of the family Bunyaviridae, causes high rates of abortion and fetal malformation in infected ruminants as well as causing neurological disorders, blindness, or lethal hemorrhagic fever in humans. RVFV is classified as a category A priority pathogen and a select agent in the U.S., and currently there are no therapeutics available for RVF patients. NSs protein, a major virulence factor of RVFV, inhibits host transcription including interferon (IFN)-β mRNA synthesis and promotes degradation of dsRNA-dependent protein kinase (PKR). NSs self-associates at the C-terminus 17 aa., while NSs at aa.210-230 binds to Sin3A-associated protein (SAP30) to inhibit the activation of IFN-β promoter. Thus, we hypothesize that NSs function(s) can be abolished by truncation of specific domains, and co-expression of nonfunctional NSs with intact NSs will result in the attenuation of NSs function by dominant-negative effect. Unexpectedly, we found that RVFV NSs truncated at aa. 6-30, 31-55, 56-80, 81-105, 106-130, 131-155, 156-180, 181-205, 206-230, 231-248 or 249-265 lack functions of IFN-β mRNA synthesis inhibition and degradation of PKR. Truncated NSs were less stable in infected cells, while nuclear localization was inhibited in NSs lacking either of aa.81-105, 106-130, 131-155, 156-180, 181-205, 206-230 or 231-248. Furthermore, none of truncated NSs had exhibited significant dominant-negative functions for NSs-mediated IFN-β suppression or PKR degradation upon co-expression in cells infected with RVFV. We also found that any of truncated NSs except for intact NSs does not interact with RVFV NSs even in the presence of intact C-terminus self-association domain. Our results suggest that conformational integrity of NSs is important for the stability, cellular localization and biological functions of RVFV NSs, and the co-expression of truncated NSs does not exhibit dominant-negative phenotype.

Functional analysis of Rift Valley fever virus NSs encoding a partial truncation.

Directory of Open Access Journals (Sweden)

Jennifer A Head

Full Text Available Rift Valley fever virus (RVFV, belongs to genus Phlebovirus of the family Bunyaviridae, causes high rates of abortion and fetal malformation in infected ruminants as well as causing neurological disorders, blindness, or lethal hemorrhagic fever in humans. RVFV is classified as a category A priority pathogen and a select agent in the U.S., and currently there are no therapeutics available for RVF patients. NSs protein, a major virulence factor of RVFV, inhibits host transcription including interferon (IFN-β mRNA synthesis and promotes degradation of dsRNA-dependent protein kinase (PKR. NSs self-associates at the C-terminus 17 aa., while NSs at aa.210-230 binds to Sin3A-associated protein (SAP30 to inhibit the activation of IFN-β promoter. Thus, we hypothesize that NSs function(s can be abolished by truncation of specific domains, and co-expression of nonfunctional NSs with intact NSs will result in the attenuation of NSs function by dominant-negative effect. Unexpectedly, we found that RVFV NSs truncated at aa. 6-30, 31-55, 56-80, 81-105, 106-130, 131-155, 156-180, 181-205, 206-230, 231-248 or 249-265 lack functions of IFN-β mRNA synthesis inhibition and degradation of PKR. Truncated NSs were less stable in infected cells, while nuclear localization was inhibited in NSs lacking either of aa.81-105, 106-130, 131-155, 156-180, 181-205, 206-230 or 231-248. Furthermore, none of truncated NSs had exhibited significant dominant-negative functions for NSs-mediated IFN-β suppression or PKR degradation upon co-expression in cells infected with RVFV. We also found that any of truncated NSs except for intact NSs does not interact with RVFV NSs even in the presence of intact C-terminus self-association domain. Our results suggest that conformational integrity of NSs is important for the stability, cellular localization and biological functions of RVFV NSs, and the co-expression of truncated NSs does not exhibit dominant-negative phenotype.

Correlation among fluoride and metals in irrigation water and soils of Ethiopian Rift Valley

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Elias Gizaw

2014-05-01

Full Text Available The levels of fluoride and selected metals in Ethiopian Rift Valley soils and irrigation water in the nearby sources were determined by fluoride ion selective electrode and flame atomic absorption spectrophotometer, respectively. The pH, conductivity, salinity and total dissolved solids in water and soil samples were also determined. Accuracy of the optimized procedure was evaluated using standard addition (spiking method and an acceptable percentage recovery was obtained. The fluoride concentrations in water samples were found in the range of 0.14-8.0 mg/L which is below the WHO limit of fluoride concentration for irrigation (less than 10 mg/L. The water soluble and total fluorides in soil were 2.3-16 µg/g and 209-1210 µg/g, respectively and are within the ranges recommended by FAO and WHO. The range of metal concentration in soil samples (µg/g dry weight basis and in water samples (mg/L respectively were: Na (684-6703, 8.6-67, Mg (1608-11229, 23-67, K (1776-4394, 1.1-20, Ca (7547-22998, 17-267, Cr (9.8-79, 0.07-0.17, Mn (143-700, 0.05-37, Co (50-112, 0.35-1.5, Ni (446-1288, 0.27-41, Fe (12180-32681, 6.0-48, Cu (8.9-45, 0.09-0.25 and Zn (31-89, 0.14-0.56. Fluoride was found to have significant correlation with major trace metals (Fe, Cu and Cr, but the correlation with other trace metals was not significant. DOI: http://dx.doi.org/10.4314/bcse.v28i2.7

Rift Valley fever virus NSs inhibits host transcription independently of the degradation of dsRNA-dependent protein kinase PKR.

Science.gov (United States)

Kalveram, Birte; Lihoradova, Olga; Indran, Sabarish V; Lokugamage, Nandadeva; Head, Jennifer A; Ikegami, Tetsuro

2013-01-20

Rift Valley fever virus (RVFV) encodes one major virulence factor, the NSs protein. NSs suppresses host general transcription, including interferon (IFN)-β mRNA synthesis, and promotes degradation of the dsRNA-dependent protein kinase (PKR). We generated a novel RVFV mutant (rMP12-NSsR173A) specifically lacking the function to promote PKR degradation. rMP12-NSsR173A infection induces early phosphorylation of eIF2α through PKR activation, while retaining the function to inhibit host general transcription including IFN-β gene inhibition. MP-12 NSs but not R173A NSs binds to wt PKR. R173A NSs formed filamentous structure in nucleus in a mosaic pattern, which was distinct from MP-12 NSs filament pattern. Due to early phosphorylation of eIF2α, rMP12-NSsR173A could not efficiently accumulate viral proteins. Our results suggest that NSs-mediated host general transcription suppression occurs independently of PKR degradation, while the PKR degradation is important to inhibit the phosphorylation of eIF2α in infected cells undergoing host general transcription suppression. Copyright © 2012 Elsevier Inc. All rights reserved.

The temporal and spatial distribution of upper crustal faulting and magmatism in the south Lake Turkana rift, East Africa

Science.gov (United States)

Muirhead, J.; Scholz, C. A.

2017-12-01

During continental breakup extension is accommodated in the upper crust largely through dike intrusion and normal faulting. The Eastern branch of the East African Rift arguably represents the premier example of active continental breakup in the presence magma. Constraining how faulting is distributed in both time and space in these regions is challenging, yet can elucidate how extensional strain localizes within basins as rifting progresses to sea-floor spreading. Studies of active rifts, such as the Turkana Rift, reveal important links between faulting and active magmatic processes. We utilized over 1100 km of high-resolution Compressed High Intensity Radar Pulse (CHIRP) 2D seismic reflection data, integrated with a suite of radiocarbon-dated sediment cores (3 in total), to constrain a 17,000 year history of fault activity in south Lake Turkana. Here, a set of N-S-striking intra-rift faults exhibit time-averaged slip-rates as high as 1.6 mm/yr, with the highest slip-rates occurring along faults within 3 km of the rift axis. Results show that strain has localized into a zone of intra-rift faults along the rift axis, forming an approximately 20 km-wide graben in central parts of the basin. Subsurface structural mapping and fault throw profile analyses reveal increasing basin subsidence and fault-related strain as this faulted graben approaches a volcanic island in the center of the basin (South Island). The long-axis of this island trends north-south, and it contains a number of elongate cones that support recent emplacement of N-S-striking dike intrusions, which parallel recently active intra-rift faults. Overall, these observations suggest strain localization into intra-rift faults in the rift center is likely a product of both volcanic loading and the mechanical and thermal effects of diking along the rift axis. These results support the establishment of magmatic segmentation in southern Lake Turkana, and highlight the importance of magmatism for focusing upper

Tectonics and stratigraphy of the East Brazil Rift system: an overview

Science.gov (United States)

Hung Kiang Chang; Kowsmann, Renato Oscar; Figueiredo, Antonio Manuel Ferreira; Bender, AndréAdriano

1992-10-01

The East Brazilian Rift system (Ebris) constitutes the northern segment of the South Atlantic rift system which developed during the Mesozoic breakup of South America and Africa. Following crustal separation in the Late Aptian, it evolved into a passive continental margin. Along the continental margin six basins are recognized, while three onshore basins form part of an aborted rift. Three continental syn-rift stratigraphic sequences are recognized, spanning Jurassic to Barremian times. The Jurassic (Syn-rift I) and Neocomian (Syn-rift II) phases were most active in the interior rift basins. During the Barremian (Syn-rift III), rift subsidence rates were twice as large as during the Neocomian (Syn-rift II), both in the interior rift and in the marginal rift segments, indicating that rift axis did not migrate from the interior to the marginal setting. Rift magmatism was centered on the southern EBRIS and peaked between 130 and 120 Ma during syn-rift phase II. Rift phase III was followed by a transitional marine, evaporitic megasequence of Aptian age, which directly overlies the rift unconformity and a marine drift megasequence which spans Albian to Recent times. During the Late Cretaceous, sedimentation rates responded to first-order eustatic sea-level fluctuations. Tertiary accelerated sedimentation rates can be related to local clastic supply which filled in spaces inherited from previous starved conditions. Between 60 and 40 Ma, post-rift magmatism, centered on the Abrolhos and Royal Charlotte banks, is probably related to development of a hot spot associated with the Vitória-Trindade Seamount Chain. Although crossing three distinct Precambrian tectono-thermal provinces, ranging from Archean through Late Proterozoic, rift structures follow a general NE trend, subparallel to the principal basement fabric. A NW-SE oriented stress field appears to be compatible with both Neocomian and Barremian phases of crustal extension. Profiles transverse to the rift axis

Adapting to climate variability and change: experiences from cereal-based farming in the central rift and Kobo Valleys, Ethiopia.

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Kassie, Belay Tseganeh; Hengsdijk, Huib; Rötter, Reimund; Kahiluoto, Helena; Asseng, Senthold; Van Ittersum, Martin

2013-11-01

Small-holder farmers in Ethiopia are facing several climate related hazards, in particular highly variable rainfall with severe droughts which can have devastating effects on their livelihoods. Projected changes in climate are expected to aggravate the existing challenges. This study examines farmer perceptions on current climate variability and long-term changes, current adaptive strategies, and potential barriers for successful further adaptation in two case study regions-the Central Rift Valley (CRV) and Kobo Valley. The study was based on a household questionnaire, interviews with key stakeholders, and focus group discussions. The result revealed that about 99 % of the respondents at the CRV and 96 % at the Kobo Valley perceived an increase in temperature and 94 % at CRV and 91 % at the Kobo Valley perceived a decrease in rainfall over the last 20-30 years. Inter-annual and intraseasonal rainfall variability also has increased according to the farmers. The observed climate data (1977-2009) also showed an increasing trend in temperature and high inter-annual and intra-seasonal rainfall variability. In contrast to farmers' perceptions of a decrease in rainfall totals, observed rainfall data showed no statistically significant decline. The interaction among various bio-physical and socio-economic factors, changes in rainfall intensity and reduced water available to crops due to increased hot spells, may have influenced the perception of farmers with respect to rainfall trends. In recent decades, farmers in both the CRV and Kobo have changed farming practices to adapt to perceived climate change and variability, for example, through crop and variety choice, adjustment of cropping calendar, and in situ moisture conservation. These relatively low-cost changes in farm practices were within the limited adaptation capacity of farmers, which may be insufficient to deal with the impacts of future climate change. Anticipated climate change is expected to impose new

Adapting to Climate Variability and Change: Experiences from Cereal-Based Farming in the Central Rift and Kobo Valleys, Ethiopia

Science.gov (United States)

Kassie, Belay Tseganeh; Hengsdijk, Huib; Rötter, Reimund; Kahiluoto, Helena; Asseng, Senthold; Van Ittersum, Martin

2013-11-01

Small-holder farmers in Ethiopia are facing several climate related hazards, in particular highly variable rainfall with severe droughts which can have devastating effects on their livelihoods. Projected changes in climate are expected to aggravate the existing challenges. This study examines farmer perceptions on current climate variability and long-term changes, current adaptive strategies, and potential barriers for successful further adaptation in two case study regions—the Central Rift Valley (CRV) and Kobo Valley. The study was based on a household questionnaire, interviews with key stakeholders, and focus group discussions. The result revealed that about 99 % of the respondents at the CRV and 96 % at the Kobo Valley perceived an increase in temperature and 94 % at CRV and 91 % at the Kobo Valley perceived a decrease in rainfall over the last 20-30 years. Inter-annual and intraseasonal rainfall variability also has increased according to the farmers. The observed climate data (1977-2009) also showed an increasing trend in temperature and high inter-annual and intra-seasonal rainfall variability. In contrast to farmers’ perceptions of a decrease in rainfall totals, observed rainfall data showed no statistically significant decline. The interaction among various bio-physical and socio-economic factors, changes in rainfall intensity and reduced water available to crops due to increased hot spells, may have influenced the perception of farmers with respect to rainfall trends. In recent decades, farmers in both the CRV and Kobo have changed farming practices to adapt to perceived climate change and variability, for example, through crop and variety choice, adjustment of cropping calendar, and in situ moisture conservation. These relatively low-cost changes in farm practices were within the limited adaptation capacity of farmers, which may be insufficient to deal with the impacts of future climate change. Anticipated climate change is expected to impose new

Comparison of Rift Valley fever virus replication in North American livestock and wildlife cell lines.

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Gaudreault, Natasha N; Indran, Sabarish V; Bryant, P K; Richt, Juergen A; Wilson, William C

2015-01-01

Rift Valley fever virus (RVFV) causes disease outbreaks across Africa and the Arabian Peninsula, resulting in high morbidity and mortality among young domestic livestock, frequent abortions in pregnant animals, and potentially severe or fatal disease in humans. The possibility of RVFV spreading to the United States or other countries worldwide is of significant concern to animal and public health, livestock production, and trade. The mechanism for persistence of RVFV during inter-epidemic periods may be through mosquito transovarial transmission and/or by means of a wildlife reservoir. Field investigations in endemic areas and previous in vivo studies have demonstrated that RVFV can infect a wide range of animals, including indigenous wild ruminants of Africa. Yet no predominant wildlife reservoir has been identified, and gaps in our knowledge of RVFV permissive hosts still remain. In North America, domestic goats, sheep, and cattle are susceptible hosts for RVFV and several competent vectors exist. Wild ruminants such as deer might serve as a virus reservoir and given their abundance, wide distribution, and overlap with livestock farms and human populated areas could represent an important risk factor. The objective of this study was to assess a variety of cell lines derived from North American livestock and wildlife for susceptibility and permissiveness to RVFV. Results of this study suggest that RVFV could potentially replicate in native deer species such as white-tailed deer, and possibly a wide range of non-ruminant animals. This work serves to guide and support future animal model studies and risk model assessment regarding this high-consequence zoonotic pathogen.

Subsurface images of the Eastern Rift, Africa, from the joint inversion of body waves, surface waves and gravity: investigating the role of fluids in early-stage continental rifting

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Roecker, S.; Ebinger, C.; Tiberi, C.; Mulibo, G.; Ferdinand-Wambura, R.; Mtelela, K.; Kianji, G.; Muzuka, A.; Gautier, S.; Albaric, J.; Peyrat, S.

2017-08-01

The Eastern Rift System (ERS) of northern Tanzania and southern Kenya, where a cratonic lithosphere is in the early stages of rifting, offers an ideal venue for investigating the roles of magma and other fluids in such an environment. To illuminate these roles, we jointly invert arrival times of locally recorded P and S body waves, phase delays of ambient noise generated Rayleigh waves and Bouguer anomalies from gravity observations to generate a 3-D image of P and S wave speeds in the upper 25 km of the crust. While joint inversion of gravity and arrival times requires a relationship between density and wave speeds, the improvement in resolution obtained by the combination of these disparate data sets serves to further constrain models, and reduce uncertainties. The most significant features in the 3-D model are (1) P and S wave speeds that are 10-15 per cent lower beneath the rift zone than in the surrounding regions, (2) a relatively high wave speed tabular feature located along the western edge of the Natron and Manyara rifts, and (3) low (∼1.71) values of Vp/Vs throughout the upper crust, with the lowest ratios along the boundaries of the rift zones. The low P and S wave speeds at mid-crustal levels beneath the rift valley are an expected consequence of active volcanism, and the tabular, high-wave speed feature is interpreted to be an uplifted footwall at the western edge of the rift. Given the high levels of CO2 outgassing observed at the surface along border fault zones, and the sensitivity of Vp/Vs to pore-fluid compressibility, we infer that the low Vp/Vs values in and around the rift zone are caused by the volcanic plumbing in the upper crust being suffused by a gaseous CO2 froth on top of a deeper, crystalline mush. The repository for molten rock is likely located in the lower crust and upper mantle, where the Vp/Vs ratios are significantly higher.

Post-exposure vaccination with MP-12 lacking NSs protects mice against lethal Rift Valley fever virus challenge.

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Gowen, Brian B; Bailey, Kevin W; Scharton, Dionna; Vest, Zachery; Westover, Jonna B; Skirpstunas, Ramona; Ikegami, Tetsuro

2013-05-01

Rift Valley fever virus (RVFV) causes severe disease in humans and livestock. There are currently no approved antivirals or vaccines for the treatment or prevention of RVF disease in humans. A major virulence factor of RVFV is the NSs protein, which inhibits host transcription including the interferon (IFN)-β gene and promotes the degradation of dsRNA-dependent protein kinase, PKR. We analyzed the efficacy of the live-attenuated MP-12 vaccine strain and MP-12 variants that lack the NSs protein as post-exposure vaccinations. Although parental MP-12 failed to elicit a protective effect in mice challenged with wild-type (wt) RVFV by the intranasal route, significant protection was demonstrated by vaccination with MP-12 strains lacking NSs when they were administered at 20-30 min post-exposure. Viremia and virus replication in liver, spleen and brain were also inhibited by post-exposure vaccination with MP-12 lacking NSs. The protective effect was mostly lost when vaccination was delayed 6 or 24 h after intranasal RVFV challenge. When mice were challenged subcutaneously, efficacy of MP-12 lacking NSs was diminished, most likely due to more rapid dissemination of wt RVFV. Our findings suggest that post-exposure vaccination with MP-12 lacking NSs may be developed as a novel post-exposure treatment to prevent RVF. Copyright © 2013 Elsevier B.V. All rights reserved.

Más allá del valle del Rift: la evidencia arqueológica del Plio-Pleistoceno fuera de África Oriental

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Ignacio de la TORRE SÁINZ

2009-12-01

Full Text Available RESUMEN: La mayor parte de los trabajos sobre la arqueología del Plio-Pleistoceno en Africa se centran en la evidencia del valle del Rift. Allí existen extensas columnas crono-estratigráficas que permiten contextualizar de forma fiable los conjuntos arqueo-paleontológicos y reconstruir así la secuencia evolutiva de nuestro género. Se suele obviar de esa forma la evidencia del resto de África, donde existen grandes áreas sedimentarias muy poco conocidas desde un punto de vista arqueológico. En este trabajo se reflexionará sobre el registro arqueológico plio-pleistocénico en las zonas alejadas del valle del Rift, y se tratará de reconstruir cómo fue la primera colonización del continente africano.ABSTRACT: Most of the works about the African Plio-Pleistocene are focused on the Rift Valley evidence. In this area there are long chrono-stratigraphical columns that build reliable contexts for the archaeo-paleontological sites, providing the reconstruction of the evolutionary sequence of our Genus. Evidence on the rest of Africa, where there are poor-known sedimentary areas from an archaeological point of view, is usually dismissed. In this work we will reflect on the Plio-Pleistocene record beyond the Rift Valley, trying to reconstruct the first settlement of the African continent.

Multi-faceted proteomic characterization of host protein complement of Rift Valley fever virus virions and identification of specific heat shock proteins, including HSP90, as important viral host factors.

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Nuss, Jonathan E; Kehn-Hall, Kylene; Benedict, Ashwini; Costantino, Julie; Ward, Michael; Peyser, Brian D; Retterer, Cary J; Tressler, Lyal E; Wanner, Laura M; McGovern, Hugh F; Zaidi, Anum; Anthony, Scott M; Kota, Krishna P; Bavari, Sina; Hakami, Ramin M

2014-01-01

Rift Valley fever is a potentially fatal disease of humans and domestic animals caused by Rift Valley fever virus (RVFV). Infection with RVFV in ruminants can cause near 100% abortion rates and recent outbreaks in naïve human populations have suggested case fatality rates of greater than thirty percent. To elucidate the roles that host proteins play during RVFV infection, proteomic analysis of RVFV virions was conducted using complementary analytical approaches, followed by functional validation studies of select identified host factors. Coupling the more traditional Gel LC/MS/MS approach (SDS PAGE followed by liquid chromatography tandem mass spectrometry) with an alternative technique that preserves protein complexes allowed the protein complement of these viral particles to be thoroughly examined. In addition to viral proteins present within the virions and virion-associated host proteins, multiple macromolecular complexes were identified. Bioinformatic analysis showed that host chaperones were among over-represented protein families associated with virions, and functional experiments using siRNA gene silencing and small molecule inhibitors identified several of these heat shock proteins, including heat shock protein 90 (HSP90), as important viral host factors. Further analysis indicated that HSP inhibition effects occur during the replication/transcription phase of the virus life cycle, leading to significant lowering of viral titers without compromising the functional capacity of released virions. Overall, these studies provide much needed further insight into interactions between RVFV and host cells, increasing our understanding of the infection process and suggesting novel strategies for anti-viral development. In particular, considering that several HSP90 inhibitors have been advancing through clinical trials for cancer treatment, these results also highlight the exciting potential of repurposing HSP90 inhibitors to treat RVF.

Multi-faceted proteomic characterization of host protein complement of Rift Valley fever virus virions and identification of specific heat shock proteins, including HSP90, as important viral host factors.

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Jonathan E Nuss

Full Text Available Rift Valley fever is a potentially fatal disease of humans and domestic animals caused by Rift Valley fever virus (RVFV. Infection with RVFV in ruminants can cause near 100% abortion rates and recent outbreaks in naïve human populations have suggested case fatality rates of greater than thirty percent. To elucidate the roles that host proteins play during RVFV infection, proteomic analysis of RVFV virions was conducted using complementary analytical approaches, followed by functional validation studies of select identified host factors. Coupling the more traditional Gel LC/MS/MS approach (SDS PAGE followed by liquid chromatography tandem mass spectrometry with an alternative technique that preserves protein complexes allowed the protein complement of these viral particles to be thoroughly examined. In addition to viral proteins present within the virions and virion-associated host proteins, multiple macromolecular complexes were identified. Bioinformatic analysis showed that host chaperones were among over-represented protein families associated with virions, and functional experiments using siRNA gene silencing and small molecule inhibitors identified several of these heat shock proteins, including heat shock protein 90 (HSP90, as important viral host factors. Further analysis indicated that HSP inhibition effects occur during the replication/transcription phase of the virus life cycle, leading to significant lowering of viral titers without compromising the functional capacity of released virions. Overall, these studies provide much needed further insight into interactions between RVFV and host cells, increasing our understanding of the infection process and suggesting novel strategies for anti-viral development. In particular, considering that several HSP90 inhibitors have been advancing through clinical trials for cancer treatment, these results also highlight the exciting potential of repurposing HSP90 inhibitors to treat RVF.

Human Dispersals Along the African Rift Valley in the Late Quaternary

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Tryon, C. A.; Faith, J. T.; Peppe, D. J.

2014-12-01

Climate- and tectonic-driven environmental dynamics of the East African Rift System (EARS) during the Quaternary played an important role in the demographic history of early Homo sapiens, including expansions of modern humans across and out of Africa. Human forager population size, geographic range, and behaviors such as hunting strategies and residential mobility likely varied in response to changes in the local and regional environment. Throughout the Quaternary, floral and faunal change was linked at least in part to variations in moisture availability, temperature, and atmospheric CO2, which in addition to uplift and faulting, contributed to the expansion and contraction of a number of large lakes that served as biogeographic barriers to many taxa. This is particularly clear for the Lake Victoria basin, where biogeographic, geological, and paleontological evidence documents repeated expansion and contraction of the ranges of species in response to lake level and vegetation change. Across much of eastern Africa, the topography of the rift facilitated north-south dispersals, the timing of which may have depended in part on the expansion and contraction of the equatorial forest belt. Dispersal potential likely increased during the more arid periods of the late Quaternary, when the roles of lakes and forests as dispersal barriers was reduced and the extent of low net primary productivity dry grasslands increased, the latter requiring large home ranges for human foragers, conditions suitable for range expansions within H. sapiens.

Dual functions of Rift Valley fever virus NSs protein: inhibition of host mRNA transcription and post-transcriptional downregulation of protein kinase PKR.

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Ikegami, Tetsuro; Narayanan, Krishna; Won, Sungyong; Kamitani, Wataru; Peters, C J; Makino, Shinji

2009-09-01

Rift Valley fever virus (RVFV), which belongs to the genus Phlebovirus, family Bunyaviridae, is a negative-stranded RNA virus carrying a single-stranded, tripartite RNA genome. RVFV is an important zoonotic pathogen transmitted by mosquitoes and causes large outbreaks among ruminants and humans in Africa and the Arabian Peninsula. Human patients develop an acute febrile illness, followed by a fatal hemorrhagic fever, encephalitis, or ocular diseases. A viral nonstructural protein, NSs, is a major viral virulence factor. Past studies showed that NSs suppresses the transcription of host mRNAs, including interferon-beta mRNAs. Here we demonstrated that the NSs protein induced post-transcriptional downregulation of dsRNA-dependent protein kinase (PKR), to prevent phosphorylation of eIF2alpha and promoted viral translation in infected cells. These two biological activities of the NSs most probably have a synergistic effect in suppressing host innate immune functions and facilitate efficient viral replication in infected mammalian hosts.

Single-Molecule FISH Reveals Non-selective Packaging of Rift Valley Fever Virus Genome Segments.

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Paul J Wichgers Schreur

2016-08-01

Full Text Available The bunyavirus genome comprises a small (S, medium (M, and large (L RNA segment of negative polarity. Although genome segmentation confers evolutionary advantages by enabling genome reassortment events with related viruses, genome segmentation also complicates genome replication and packaging. Accumulating evidence suggests that genomes of viruses with eight or more genome segments are incorporated into virions by highly selective processes. Remarkably, little is known about the genome packaging process of the tri-segmented bunyaviruses. Here, we evaluated, by single-molecule RNA fluorescence in situ hybridization (FISH, the intracellular spatio-temporal distribution and replication kinetics of the Rift Valley fever virus (RVFV genome and determined the segment composition of mature virions. The results reveal that the RVFV genome segments start to replicate near the site of infection before spreading and replicating throughout the cytoplasm followed by translocation to the virion assembly site at the Golgi network. Despite the average intracellular S, M and L genome segments approached a 1:1:1 ratio, major differences in genome segment ratios were observed among cells. We also observed a significant amount of cells lacking evidence of M-segment replication. Analysis of two-segmented replicons and four-segmented viruses subsequently confirmed the previous notion that Golgi recruitment is mediated by the Gn glycoprotein. The absence of colocalization of the different segments in the cytoplasm and the successful rescue of a tri-segmented variant with a codon shuffled M-segment suggested that inter-segment interactions are unlikely to drive the copackaging of the different segments into a single virion. The latter was confirmed by direct visualization of RNPs inside mature virions which showed that the majority of virions lack one or more genome segments. Altogether, this study suggests that RVFV genome packaging is a non-selective process.

Seroprevalence of Infections with Dengue, Rift Valley Fever and Chikungunya Viruses in Kenya, 2007.

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Caroline Ochieng

Full Text Available Arthropod-borne viruses are a major constituent of emerging infectious diseases worldwide, but limited data are available on the prevalence, distribution, and risk factors for transmission in Kenya and East Africa. In this study, we used 1,091 HIV-negative blood specimens from the 2007 Kenya AIDS Indicator Survey (KAIS 2007 to test for the presence of IgG antibodies to dengue virus (DENV, chikungunya virus (CHIKV and Rift Valley fever virus (RVFV.The KAIS 2007 was a national population-based survey conducted by the Government of Kenya to provide comprehensive information needed to address the HIV/AIDS epidemic. Antibody testing for arboviruses was performed on stored blood specimens from KAIS 2007 through a two-step sandwich IgG ELISA using either commercially available kits or CDC-developed assays. Out of the 1,091 samples tested, 210 (19.2% were positive for IgG antibodies against at least one of the three arboviruses. DENV was the most common of the three viruses tested (12.5% positive, followed by RVFV and CHIKV (4.5% and 0.97%, respectively. For DENV and RVFV, the participant's province of residence was significantly associated (P≤.01 with seropositivity. Seroprevalence of DENV and RVFV increased with age, while there was no correlation between province of residence/age and seropositivity for CHIKV. Females had twelve times higher odds of exposure to CHIK as opposed to DENV and RVFV where both males and females had the same odds of exposure. Lack of education was significantly associated with a higher odds of previous infection with either DENV or RVFV (p <0.01. These data show that a number of people are at risk of arbovirus infections depending on their geographic location in Kenya and transmission of these pathogens is greater than previously appreciated. This poses a public health risk, especially for DENV.

Exploratory space-time analyses of Rift Valley Fever in South Africa in 2008-2011.

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Raphaëlle Métras

Full Text Available Rift Valley fever (RVF is a zoonotic arbovirosis for which the primary hosts are domestic livestock (cattle, sheep and goats. RVF was first described in South Africa in 1950-1951. Mechanisms for short and long distance transmission have been hypothesised, but there is little supporting evidence. Here we describe RVF occurrence and spatial distribution in South Africa in 2008-11, and investigate the presence of a contagious process in order to generate hypotheses on the different mechanisms of transmission.A total of 658 cases were extracted from World Animal Health Information Database. Descriptive statistics, epidemic curves and maps were produced. The space-time K-function was used to test for evidence of space-time interaction. Five RVF outbreak waves (one in 2008, two in 2009, one in 2010 and one in 2011 of varying duration, location and size were reported. About 70% of cases (n = 471 occurred in 2010, when the epidemic was almost country-wide. No strong evidence of space-time interaction was found for 2008 or the second wave in 2009. In the first wave of 2009, a significant space-time interaction was detected for up to one month and over 40 km. In 2010 and 2011 a significant intense, short and localised space-time interaction (up to 3 days and 15 km was detected, followed by one of lower intensity (up to 2 weeks and 35 to 90 km.The description of the spatiotemporal patterns of RVF in South Africa between 2008 and 2011 supports the hypothesis that during an epidemic, disease spread may be supported by factors other than active vector dispersal. Limitations of under-reporting and space-time K-function properties are discussed. Further spatial analyses and data are required to explain factors and mechanisms driving RVF spread.

Stress and slip partitioning during oblique rifting: comparison between data from the Main Ethiopian Rift and laboratory experiments

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Corti, G.; Philippon, M.; Sani, F.; Keir, D.

2012-04-01

Oblique rifting in the central and northern Main Ethiopian Rift (MER) has resulted in a complex structural pattern characterized by two differently oriented fault systems: a set of NE-SW-trending boundary faults and a system of roughly NNE-SSW-oriented fault swarms affecting the rift floor (Wonji faults). Boundary faults formed oblique to the regional extension vector, likely as a result of the oblique reactivation of a pre-existing deep-seated rheological anisotropy, whereas internal Wonji faults developed sub-orthogonal to the stretching direction. Previous works have successfully reconciled this rift architecture and fault distribution with the long-term plate kinematics; however, at a more local scale, fault-slip and earthquake data reveal significant variations in the orientation the minimum principal stress and related fault-slip direction across the rift valley. Whereas fault measurements indicate a roughly N95°E extension on the axial Wonji faults, a N105°E to N110°E directed minimum principal stress is observed along boundary faults. Both fault-slip data and analysis of seismicity indicate a roughly pure dip-slip motion on the boundary faults, despite their orientation (oblique to the regional extension vector) should result in an oblique displacement. To shed light on the process driving the variability of data derived from fault-slip (and seismicity) analysis we present crustal-scale analogue models of oblique rifting, deformed in a large-capacity centrifuge by using materials and boundary conditions described in several previous modeling works. As in these previous works, the experiments show the diachronous activation of two fault systems, boundary and internal, whose pattern strikingly resemble that observed in previous lithospheric-scale modeling, as well as that described in the MER. Internal faults arrange in two different, en-echelon segments connected by a transfer zone where strike-slip displacement dominates. Whereas internal faults develop

Climate teleconnections and recent patterns of human and animal disease outbreaks.

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Assaf Anyamba

2012-01-01

Full Text Available Recent clusters of outbreaks of mosquito-borne diseases (Rift Valley fever and chikungunya in Africa and parts of the Indian Ocean islands illustrate how interannual climate variability influences the changing risk patterns of disease outbreaks. Although Rift Valley fever outbreaks have been known to follow periods of above-normal rainfall, the timing of the outbreak events has largely been unknown. Similarly, there is inadequate knowledge on climate drivers of chikungunya outbreaks. We analyze a variety of climate and satellite-derived vegetation measurements to explain the coupling between patterns of climate variability and disease outbreaks of Rift Valley fever and chikungunya.We derived a teleconnections map by correlating long-term monthly global precipitation data with the NINO3.4 sea surface temperature (SST anomaly index. This map identifies regional hot-spots where rainfall variability may have an influence on the ecology of vector borne disease. Among the regions are Eastern and Southern Africa where outbreaks of chikungunya and Rift Valley fever occurred 2004-2009. Chikungunya and Rift Valley fever case locations were mapped to corresponding climate data anomalies to understand associations between specific anomaly patterns in ecological and climate variables and disease outbreak patterns through space and time. From these maps we explored associations among Rift Valley fever disease occurrence locations and cumulative rainfall and vegetation index anomalies. We illustrated the time lag between the driving climate conditions and the timing of the first case of Rift Valley fever. Results showed that reported outbreaks of Rift Valley fever occurred after ∼3-4 months of sustained above-normal rainfall and associated green-up in vegetation, conditions ideal for Rift Valley fever mosquito vectors. For chikungunya we explored associations among surface air temperature, precipitation anomalies, and chikungunya outbreak locations. We found

Late oligocene and miocene faulting and sedimentation, and evolution of the southern Rio Grande rift, New Mexico, USA

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Mack, Greg H.; Seager, William R.; Kieling, John

1994-08-01

The distribution of nonmarine lithofacies, paleocurrents, and provenance data are used to define the evolution of late Oligocene and Miocene basins and complementary uplifts in the southern Rio Grande rift in the vicinity of Hatch, New Mexico, USA. The late Oligocene-middle Miocene Hayner Ranch Formation, which consists of a maximum of 1000 m of alluvial-fan, alluvial-flat, and lacustrine-carbonate lithofacies, was deposited in a narrow (12 km), northwest-trending, northeast-tilted half graben, whose footwall was the Caballo Mountains block. Stratigraphic separation on the border faults of the Caballo Mountains block was approximately 1615 m. An additional 854 m of stratigraphic separation along the Caballo Mountains border faults occurred during deposition of the middle-late Miocene Rincon Valley Formation, which is composed of up to 610 m of alluvial-fan, alluvial-flat, braided-fluvial, and gypsiferous playa lithofacies. Two new, north-trending fault blocks (Sierra de las Uvas and Dona Ana Mountains) and complementary west-northwest-tilted half graben also developed during Rincon Valley time, with approximately 549 m of stratigraphic separation along the border fault of the Sierra de las Uvas block. In latest Miocene and early Pliocene time, following deposition of the Rincon Valley Formation, movement continued along the border faults of the Caballo Mountains, Dona Ana Mountains, and Sierra de las Uvas blocks, and large parts of the Hayner Ranch and Rincon Valley basins were segmented into smaller fault blocks and basins by movement along new, largely north-trending faults. Analysis of the Hayner Ranch and Rincon Valley Formations, along with previous studies of the early Oligocene Bell Top Formation and late Pliocene-early Pleistocene Camp Rice Formation, indicate that the traditional two-stage model for development of the southern Rio Grande rift should be abandoned in favor of at least four episodes of block faulting beginning 35 Ma ago. With the exception of

The NE Rift of Tenerife: towards a model on the origin and evolution of ocean island rifts; La dorsal NE de Tenerife: hacia un modelo del origen y evolucion de los rifts de islas oceanicas

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Carracedo, J. C.; Guillou, H.; Rodriguez Badiola, E.; Perez-Torrado, F. J.; Rodriguez Gonzalez, A.; Peris, R.; Troll, V.; Wiesmaier, S.; Delcamp, A.; Fernandez-Turiel, J. L.

2009-07-01

The NE Rift of Tenerife is an excellent example of a persistent, recurrent rift, providing important evidence of the origin and dynamics of these major volcanic features. The rift developed in three successive, intense and relatively short eruptive stages (a few hundred ka), separated by longer periods of quiescence or reduced activity: A Miocene stage (7266 {+-}156 ka), apparently extending the central Miocene shield of Tenerife towards the Anaga massif; an Upper Pliocene stage (2710{+-} 58 ka) and the latest stage, with the main eruptive phase in the Pleistocene. Detailed geological (GIS) mapping, geomagnetic reversal mapping and stratigraphic correlation, and radioisotopic (K/Ar) dating of volcanic formations allowed the reconstruction of the latest period of rift activity. In the early phases of this stage the majority of the eruptions grouped tightly along the axis of the rift and show reverse polarity (corresponding to the Matuyama chron). Dykes are of normal and reverse polarities. In the final phase of activity, eruptions are more disperse and lavas and dykes are consistently of normal polarity (Brunhes chron). Volcanic units of normal polarity crossed by dykes of normal and reverse polarities yield ages apparently compatible with normal subchrons (M-B Precursor and Jaramillo) in the Upper Matuyama chron. Three lateral collapses successively mass-wasted the rift: The Micheque collapse, completely concealed by subsequent nested volcanism, and the Guimar and La Orotava collapses, that are only partially filled. Time occurrence of collapses in the NE rift apparently coincides with glacial stages, suggesting that giant landslides may be finally triggered by sea level chan-ges during glaciations. Pre-collapse and nested volcanism is predominantly basaltic, except in the Micheque collapse, where magmas evolved towards intermediate and felsic (trachytic) compositions. Rifts in the Canary Islands are long-lasting, recurrent features, probably related to primordial

Geodetic constraints on present-day motion of the Arabian Plate: Implications for Red Sea and Gulf of Aden rifting

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Arrajehi, Abdullah; McClusky, Simon; Reilinger, Robert; Daoud, Mohamed; Alchalbi, Abdulmutaleb; Ergintav, Semih; Gomez, Francisco; Sholan, Jamal; Bou-Rabee, Firyal; Ogubazghi, Ghebrebrhan; Haileab, Biniam; Fisseha, Shimelles; Asfaw, Laike; Mahmoud, Salah; Rayan, Ali; Bendik, Rebecca; Kogan, Lewis

2010-06-01

Five years of continuously recording GPS observations in the Kingdom of Saudi Arabia together with new continuous and survey-mode GPS observations broadly distributed across the Arabian Peninsula provide the basis for substantially improved estimates of present-day motion and internal deformation of the Arabian plate. We derive the following relative, geodetic Euler vectors (latitude (°N), longitude (°E), rate (°/Myr, counterclockwise)) for Arabia-Nubia (31.7 ± 0.2, 24.6 ± 0.3, 0.37 ± 0.01), Arabia-Somalia (22.0 ± 0.5, 26.2 ± 0.5, 0.40 ± 0.01), Arabia-India (18.0 ± 3.8, 87.6 ± 3.3, 0.07 ± 0.01), Arabia-Sinai (35.7 ± 0.8, 17.1 ± 5.0, 0.15 ± 0.04), and Arabia-Eurasia (27.5 ± 0.1, 17.6 ± 0.3, 0.404 ± 0.004). We use these Euler vectors to estimate present-day stability of the Arabian plate, the rate and direction of extension across the Red Sea and Gulf of Aden, and slip rates along the southern Dead Sea fault south of the Lebanon restraining bend (4.5-4.7 ± 0.2 mm/yr, left lateral; 0.8-1.1 ± 0.3 mm/yr extension) and the Owens fracture zone (3.2-2.5 ± 0.5 mm/yr, right lateral, increasing from north to south; 1-2 mm/yr extension). On a broad scale, the Arabian plate has no resolvable internal deformation (weighted root mean square of residual motions for Arabia equals 0.6 mm/yr), although there is marginally significant evidence for N-S shortening in the Palmyride Mountains, Syria at ≤ 1.5 mm/yr. We show that present-day Arabia plate motion with respect to Eurasia is consistent within uncertainties (i.e., ±10%) with plate tectonic estimates since the early Miocene when Arabia separated from Nubia. We estimate the time of Red Sea and Gulf of Aden rifting from present-day Arabia motion, plate tectonic evidence for a 70% increase in Arabia-Nubia relative motion at 13 Ma, and the width of the Red Sea and Gulf of Aden and find that rifting initiated roughly simultaneously (±2.2 Myr) along the strike of the Red Sea from the Gulf of Suez to the Afar

Broad accommodation of rift-related extension recorded by dyke intrusion in Saudi Arabia

KAUST Repository

Pallister, John S.

2010-09-26

The extensive harrat lava province of Arabia formed during the past 30 million years in response to Red Sea rifting and mantle upwelling. The area was regarded as seismically quiet, but between April and June 2009 a swarm of more than 30,000 earthquakes struck one of the lava fields in the province, Harrat Lunayyir, northwest Saudi Arabia. Concerned that larger damaging earthquakes might occur, the Saudi Arabian government evacuated 40,000 people from the region. Here we use geologic, geodetic and seismic data to show that the earthquake swarm resulted from magmatic dyke intrusion. We document a surface fault rupture that is 8 km long with 91 cm of offset. Surface deformation is best modelled by the shallow intrusion of a north-west trending dyke that is about 10 km long. Seismic waves generated during the earthquakes exhibit overlapping very low- and high-frequency components. We interpret the low frequencies to represent intrusion of magma and the high frequencies to represent fracturing of the crystalline basement rocks. Rather than extension being accommodated entirely by the central Red Sea rift axis, we suggest that the broad deformation observed in Harrat Lunayyir indicates that rift margins can remain as active sites of extension throughout rifting. Our analyses allowed us to forecast the likelihood of a future eruption or large earthquake in the region and informed the decisions made by the Saudi Arabian government to return the evacuees. © 2010 Macmillan Publishers Limited. All rights reserved.

Broad accommodation of rift-related extension recorded by dyke intrusion in Saudi Arabia

KAUST Repository

Pallister, John S.; McCausland, Wendy A.; Jonsson, Sigurjon; Lu, Zhong; Zahran, Hani M.; El-Hadidy, Salah Y.; Aburukbah, Abdallah; Stewart, Ian C F; Lundgren, Paul R.; White, Randal A.; Moufti, Mohammed Rashad H

2010-01-01

The extensive harrat lava province of Arabia formed during the past 30 million years in response to Red Sea rifting and mantle upwelling. The area was regarded as seismically quiet, but between April and June 2009 a swarm of more than 30,000 earthquakes struck one of the lava fields in the province, Harrat Lunayyir, northwest Saudi Arabia. Concerned that larger damaging earthquakes might occur, the Saudi Arabian government evacuated 40,000 people from the region. Here we use geologic, geodetic and seismic data to show that the earthquake swarm resulted from magmatic dyke intrusion. We document a surface fault rupture that is 8 km long with 91 cm of offset. Surface deformation is best modelled by the shallow intrusion of a north-west trending dyke that is about 10 km long. Seismic waves generated during the earthquakes exhibit overlapping very low- and high-frequency components. We interpret the low frequencies to represent intrusion of magma and the high frequencies to represent fracturing of the crystalline basement rocks. Rather than extension being accommodated entirely by the central Red Sea rift axis, we suggest that the broad deformation observed in Harrat Lunayyir indicates that rift margins can remain as active sites of extension throughout rifting. Our analyses allowed us to forecast the likelihood of a future eruption or large earthquake in the region and informed the decisions made by the Saudi Arabian government to return the evacuees. © 2010 Macmillan Publishers Limited. All rights reserved.

Broad accommodation of rift-related extension recorded by dyke intrusion in Saudi Arabia

Science.gov (United States)

Pallister, J.S.; McCausland, W.A.; Jonsson, Sigurjon; Lu, Z.; Zahran, H.M.; El, Hadidy S.; Aburukbah, A.; Stewart, I.C.F.; Lundgren, P.R.; White, R.A.; Moufti, M.R.H.

2010-01-01

The extensive harrat lava province of Arabia formed during the past 30 million years in response to Red Sea rifting and mantle upwelling. The area was regarded as seismically quiet, but between April and June 2009 a swarm of more than 30,000 earthquakes struck one of the lava fields in the province, Harrat Lunayyir, northwest Saudi Arabia. Concerned that larger damaging earthquakes might occur, the Saudi Arabian government evacuated 40,000 people from the region. Here we use geologic, geodetic and seismic data to show that the earthquake swarm resulted from magmatic dyke intrusion. We document a surface fault rupture that is 8 km long with 91 cm of offset. Surface deformation is best modelled by the shallow intrusion of a north-west trending dyke that is about 10 km long. Seismic waves generated during the earthquakes exhibit overlapping very low- and high-frequency components. We interpret the low frequencies to represent intrusion of magma and the high frequencies to represent fracturing of the crystalline basement rocks. Rather than extension being accommodated entirely by the central Red Sea rift axis, we suggest that the broad deformation observed in Harrat Lunayyir indicates that rift margins can remain as active sites of extension throughout rifting. Our analyses allowed us to forecast the likelihood of a future eruption or large earthquake in the region and informed the decisions made by the Saudi Arabian government to return the evacuees.

The seismicity related to the southern part of the Kenya Rift

Science.gov (United States)

Hollnack, D.; Stangl, R.

1998-04-01

In 1990 the Geology Department of the University of Nairobi started to build up a seismological network for Kenya, which has been operating since 1993. In this paper the actual state of this seismological network is described. Additionally, the first results on the seismic activity in the southern part of Kenya and adjacent areas between October 1993 and August 1996 are presented and are compared with historical data. Out of more than 2000 recorded local earthquakes 435 could be localised within the study area with local magnitudes of up to 5. The distribution of the events shows three areas of prominent seismicity: the Rift Valley between Nakuru and northern Tanzania; the area northeast of Kilimanjaro; and the Nyanza Rift in western Kenya. In a first attempt to assess the seismic hazard for the study area, a seismic energy map for the period of observation is given.

Safety and Efficacy Profile of Commercial Veterinary Vaccines against Rift Valley Fever: A Review Study

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Moataz Alhaj

2016-01-01

Full Text Available Rift Valley Fever (RVF is an infectious illness with serious clinical manifestations and health consequences in humans as well as a wide range of domestic ruminants. This review provides significant information about the prevention options of RVF along with the safety-efficacy profile of commercial vaccines and some of RVF vaccination strategies. Information presented in this paper was obtained through a systematic investigation of published data about RVF vaccines. Like other viral diseases, the prevention of RVF relies heavily on immunization of susceptible herds with safe and cost-effective vaccine that is able to confer long-term protective immunity. Several strains of RVF vaccines have been developed and are available in commercial production including Formalin-Inactivated vaccine, live attenuated Smithburn vaccine, and the most recent Clone13. Although Formalin-Inactivated vaccine and live attenuated Smithburn vaccine are immunogenic and widely used in prevention programs, they proved to be accompanied by significant concerns. Despite Clone13 vaccine being suggested as safe in pregnant ewes and as highly immunogenic along with its potential for differentiating infected from vaccinated animals (DIVA, a recent study raised concerns about the safety of the vaccine during the first trimester of gestation. Accordingly, RVF vaccines that are currently available in the market to a significant extent do not fulfill the requirements of safety, potency, and DIVA. These adverse effects stressed the need for developing new vaccines with an excellent safety profile to bridge the gap in safety and immunity. Bringing RVF vaccine candidates to local markets besides the absence of validated serological test for DIVA remain the major challenges of RVF control.

Maize Response to Fertilizer Dosing at Three Sites in the Central Rift Valley of Ethiopia

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Getachew Sime

2014-09-01

Full Text Available This study examines the agronomic response, efficiency and profitability of fertilizer microdosing in maize. An experiment with the following treatments was conducted: control without fertilizer, microdosing treatments, with the rate of 27 + 27, 53 + 53 and 80 + 80 kg ha−1, and banding of fertilizer with 100 + 100 kg ha−1 of di ammonium phosphate (DAP + urea, applied at planting and jointing, respectively. The treatments were arranged in a randomized complete block design with four replications. The experiment was conducted during the 2011/2012 and 2012/2013 cropping seasons at Ziway, Melkassa and Hawassa in the semiarid central rift valley region of Ethiopia. Compared to the control, the fertilizer treatments had higher yield and fertilizer use efficiency (FUE profitably. The 27 + 27 kg ha−1 fertilizer rate increased the grain yield by 19, 45 and 46% at Hawassa, Ziway and Melkassa, respectively, and it was equivalent to the higher rates. The value cost ratio (VCR was highest with the lowest fertilizer rate, varying between seven and 11 in the treatment with 27 + 27 kg ha−1, but two and three in the banding treatment. Similarly, FUE was highest with the lowest fertilizer rate, varying between 23 and 34 kg kg−1 but 7 and 8 kg kg−1 in the banding treatment. The improved yield, FUE, VCR and gross margin in maize with microdosing at the 27 + 27 kg ha−1 of DAP + urea rate makes it low cost, low risk, high yielding and profitable. Therefore, application of this particular rate in maize may be an option for the marginal farmers in the region with similar socioeconomic and agroecological conditions.

Mercury in fish from three rift valley lakes (Turkana, Naivasha and Baringo), Kenya, East Africa

Energy Technology Data Exchange (ETDEWEB)

Campbell, L.M.; Osano, O.; Hecky, R.E.; Dixon, D.G

2003-09-01

Mercury concentrations in Kenyan fish vary with tropic position but, in general, do not pose an unacceptable risk to human consumers of wildlife. -Total mercury (THg) concentrations were measured for various fish species from Lakes Turkana, Naivasha and Baringo in the rift valley of Kenya. The highest THg concentration (636 ng g{sup -1} wet weight) was measured for a piscivorous tigerfish Hydrocynus forskahlii from Lake Turkana. THg concentrations for the Perciformes species, the Nile perch Lates niloticus from Lake Turkana and the largemouth bass Micropterus salmoides from Lake Naivasha ranged between 4 and 95 ng g{sup -1}. The tilapiine species in all lakes, including the Nile tilapia Oreochromis niloticus, had consistently low THg concentrations ranging between 2 and 25 ng g{sup -1}. In Lake Naivasha, the crayfish species, Procambrus clarkii, had THg concentrations similar to those for the tilapiine species from the same lake, which is consistent with their shared detritivore diet. THg concentrations in all fish species were usually consistent with their known trophic position, with highest concentrations in piscivores and declining in omnivores, insectivores and detritivores. One exception is the detritivore Labeo cylindricus from Lake Baringo, which had surprisingly elevated THg concentrations (mean=75 ng g{sup -1}), which was similar to those for the top trophic species (Clarias and Protopterus) in the same lake. Except for two Hydrocynus forskahlii individuals from Lake Turkana, which had THg concentrations near or above the international marketing limit of 500 ng g{sup -1}, THg concentrations in the fish were generally below those of World Health Organization's recommended limit of 200 ng g{sup -1} for at-risk groups.

Fine-scale heat flow, shallow heat sources, and decoupled circulation systems at two sea-floor hydrothermal sites, Middle Valley, northern Juan de Fuca Ridge

Science.gov (United States)

Stein, J. S.; Fisher, A. T.; Langseth, M.; Jin, W.; Iturrino, G.; Davis, E.

1998-12-01

Fine-scale heat-flow patterns at two areas of active venting in Middle Valley, a sedimented rift on the northern Juan de Fuca Ridge, provide thermal evidence of shallow hydrothermal reservoirs beneath the vent fields. The extreme variability of heat flow is explained by conductive heating immediately adjacent to vents and shallow circulation within sediments above the reservoir. This secondary circulation is hydrologically separated from the deeper system feeding the vents by a shallow conductive lid within the sediments. A similar separation of shallow and deep circulation may also occur at sediment-free ridge-crest hydrothermal environments.

Factors associated with severe human Rift Valley fever in Sangailu, Garissa County, Kenya.

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A Desirée LaBeaud

2015-03-01

Full Text Available Mosquito-borne Rift Valley fever virus (RVFV causes acute, often severe, disease in livestock and humans. To determine the exposure factors and range of symptoms associated with human RVF, we performed a population-based cross-sectional survey in six villages across a 40 km transect in northeastern Kenya.A systematic survey of the total populations of six Northeastern Kenyan villages was performed. Among 1082 residents tested via anti-RVFV IgG ELISA, seroprevalence was 15% (CI95%, 13-17%. Prevalence did not vary significantly among villages. Subject age was a significant factor, with 31% (154/498 of adults seropositive vs. only 2% of children ≤15 years (12/583. Seroprevalence was higher among men (18% than women (13%. Factors associated with seropositivity included a history of animal exposure, non-focal fever symptoms, symptoms related to meningoencephalitis, and eye symptoms. Using cluster analysis in RVFV positive participants, a more severe symptom phenotype was empirically defined as having somatic symptoms of acute fever plus eye symptoms, and possibly one or more meningoencephalitic or hemorrhagic symptoms. Associated with this more severe disease phenotype were older age, village, recent illness, and loss of a family member during the last outbreak. In multivariate analysis, sheltering livestock (aOR = 3.5 CI95% 0.93-13.61, P = 0.065, disposing of livestock abortus (aOR = 4.11, CI95% 0.63-26.79, P = 0.14, and village location (P = 0.009 were independently associated with the severe disease phenotype.Our results demonstrate that a significant proportion of the population in northeastern Kenya has been infected with RVFV. Village and certain animal husbandry activities were associated with more severe disease. Older age, male gender, herder occupation, killing and butchering livestock, and poor visual acuity were useful markers for increased RVFV infection. Formal vision testing may therefore prove to be a helpful, low-technology tool

Analysis of gravity anomalies in the Ulleung Basin (East Sea/Sea of Japan) and its implications for the crustal structure of rift-dominated back-arc basin

Science.gov (United States)

Kim, Yoon-Mi; Lee, Sang-Mook

2018-01-01

The Ulleung Basin (UB), one of three major basins in the East Sea/Sea of Japan, is considered to represent a continental-rifting end-member of back-arc basin system, but is much less understood compared to the nearby Yamato Basin (YB) and Japan Basin (JB). This study examines the gravity anomalies of the UB since the variation in crustal thickness can provide important insights on the mode of extension during basin opening. Our analysis shows that the Moho depth (from the sea surface) varies from 16 km at the basin center to 22 km at the edges. However, within the central part of the basin, the crustal thickness (not including sediment) is more or less the same (10-12 km), by varying only about 10-20% of the total thickness, contrary to the previous suggestions. Our finding of anomalous but uniformly thick crust is consistent with the recent seismic results from the YB (14 km on average). A mantle residual gravity anomaly high (∼20 mGal) exists in the northeastern part of the UB. This feature is interpreted as the location of maximum extension (slightly thinner crust by ∼1 km). Together with another moderate gravity high to the southwest, the two anomalies form a NNE-SSW line, which corresponds to the direction of the major tectonic structures of the Korean Peninsula. We argue that the a massive magmatic emplacement took place extensively in the lower crust of the UB during the opening, significantly increasing its overall thickness to almost twice as that of the JB where a mid-ocean-ridge style seafloor spreading occurred. Two important post-opening processes took place after the formation of uniformly thick crust: post-rift volcanic intrusions in the north, especially in its northeast sections but had little effect on the residual gravity anomaly itself, and the deflection of crust in response to differential sediment loading towards the south, producing the median high in the basement in response to the flexural bending. We also conducted a simple test to

Wetlands, wild Bovidae species richness and sheep density delineate risk of Rift Valley fever outbreaks in the African continent and Arabian Peninsula.

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Michael G Walsh

2017-07-01

Full Text Available Rift Valley fever (RVF is an emerging, vector-borne viral zoonosis that has significantly impacted public health, livestock health and production, and food security over the last three decades across large regions of the African continent and the Arabian Peninsula. The potential for expansion of RVF outbreaks within and beyond the range of previous occurrence is unknown. Despite many large national and international epidemics, the landscape epidemiology of RVF remains obscure, particularly with respect to the ecological roles of wildlife reservoirs and surface water features. The current investigation modeled RVF risk throughout Africa and the Arabian Peninsula as a function of a suite of biotic and abiotic landscape features using machine learning methods. Intermittent wetland, wild Bovidae species richness and sheep density were associated with increased landscape suitability to RVF outbreaks. These results suggest the role of wildlife hosts and distinct hydrogeographic landscapes in RVF virus circulation and subsequent outbreaks may be underestimated. These results await validation by studies employing a deeper, field-based interrogation of potential wildlife hosts within high risk taxa.

Detection and identification of Rift Valley fever virus in mosquito vectors by quantitative real-time PCR.

Science.gov (United States)

Mwaengo, D; Lorenzo, G; Iglesias, J; Warigia, M; Sang, R; Bishop, R P; Brun, A

2012-10-01

Diagnostic methods allowing for rapid identification of pathogens are crucial for controlling and preventing dissemination after disease outbreaks as well as for use in surveillance programs. For arboviruses, detection of the presence of virus in their arthropod hosts is important for monitoring of viral activity and quantitative information is useful for modeling of transmission dynamics. In this study, molecular detection of Rift Valley fever virus (RVFV) in mosquito samples from the 2006 to 2007 East African outbreaks was performed using quantitative real-time PCR assay (qRT-PCR). Specific RVFV sequence-based primer/fluorogenic (TaqMan) probe sets were derived from the L and S RNA segments of the virus. Both primer-probe L and S segment-based combinations detected genomic RVFV sequences, with generally comparable levels of sensitivity. Viral loads from three mosquito species, Aedes mcintoshi, Aedes ochraceus and Mansonia uniformis were estimated and significant differences of between 5- and 1000-fold were detected between Ae. mcintoshi and M. uniformis using both the L and S primer-probe-based assays. The genetic relationships of the viral sequences in mosquito samples were established by partial M segment sequencing and assigned to the two previously described viral lineages defined by analysis of livestock isolates obtained during the 2006-2007 outbreak, confirming that similar viruses were present in both the vector and mammalian host. The data confirms the utility of qRT-PCR for identification and initial quantification of virus in mosquito samples during RVFV outbreaks. Copyright © 2012 Elsevier B.V. All rights reserved.

Experimental transmission of West Nile Virus and Rift Valley Fever Virus by Culex pipiens from Lebanon.

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Renée Zakhia

2018-01-01

Full Text Available West Nile virus (WNV and Rift Valley fever virus (RVFV are two emerging arboviruses transmitted by Culex pipiens species that includes two biotypes: pipiens and molestus. In Lebanon, human cases caused by WNV and RVFV have never been reported. However, the introduction of these viruses in the country is likely to occur through the migratory birds and animal trades. In this study, we evaluated the ability of Cx. pipiens, a predominant mosquito species in urban and rural regions in Lebanon, to transmit WNV and RVFV. Culex egg rafts were collected in the West Bekaa district, east of Lebanon and adult females of Cx. pipiens were experimentally infected with WNV and RVFV Clone 13 strain at titers of 1.6×108 and 1.33×107 plaque forming units (PFU/mL, respectively. We estimated viral infection, dissemination and transmission at 3, 7, 14 and 19 days post infection (dpi. Results showed that infection was higher for WNV than for RVFV from 3 dpi to 19 dpi. Viral dissemination and transmission started from 3 dpi for WNV; and only from 19 dpi for RVFV. Moreover, Cx. pipiens were able to excrete in saliva a higher number of viral particles of WNV (1028 ± 405 PFU/saliva at 19 dpi than RVFV (42 PFU/saliva at 19 dpi. Cx. pipiens from Lebanon are efficient experimental vectors of WNV and to a lower extent, RVFV. These findings should stimulate local authorities to establish an active entomological surveillance in addition to animal surveys for both viruses in the country.

Rift Valley fever in a zone potentially occupied by Aedes vexans in Senegal: dynamics and risk mapping

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Cécile Vignolles

2009-05-01

Full Text Available This paper presents an analysis of the interaction between the various variables associated with Rift Valley fever (RVF such as the mosquito vector, available hosts and rainfall distribution. To that end, the varying zones potentially occupied by mosquitoes (ZPOM, rainfall events and pond dynamics, and the associated exposure of hosts to the RVF virus by Aedes vexans, were analyzed in the Barkedji area of the Ferlo, Senegal, during the 2003 rainy season. Ponds were identified by remote sensing using a high-resolution SPOT-5 satellite image. Additional data on ponds and rainfall events from the Tropical Rainfall Measuring Mission were combined with in-situ entomological and limnimetric measurements, and the localization of vulnerable ruminant hosts (data derived from QuickBird satellite. Since “Ae. vexans productive events” are dependent on the timing of rainfall for their embryogenesis (six days without rain are necessary to trigger hatching, the dynamic spatio-temporal distribution of Ae. vexans density was based on the total rainfall amount and pond dynamics. Detailed ZPOM mapping was obtained on a daily basis and combined with aggressiveness temporal profiles. Risks zones, i.e. zones where hazards and vulnerability are combined, are expressed by the percentages of parks where animals are potentially exposed to mosquito bites. This new approach, simply relying upon rainfall distribution evaluated from space, is meant to contribute to the implementation of a new, operational early warning system for RVF based on environmental risks linked to climatic and environmental conditions.

NSs Protein of Rift Valley Fever Virus Promotes Posttranslational Downregulation of the TFIIH Subunit p62▿

Science.gov (United States)

Kalveram, Birte; Lihoradova, Olga; Ikegami, Tetsuro

2011-01-01

Rift Valley fever virus (RVFV; family Bunyaviridae, genus Phlebovirus) is an important emerging pathogen of humans and ruminants. Its NSs protein has previously been identified as a major virulence factor that suppresses host defense through three distinct mechanisms: it directly inhibits beta interferon (IFN-β) promoter activity, it promotes the degradation of double-stranded RNA-dependent protein kinase (PKR), and it suppresses host transcription by disrupting the assembly of the basal transcription factor TFIIH through sequestration of its p44 subunit. Here, we report that in addition to PKR, NSs also promotes the degradation of the TFIIH subunit p62. Infection of cells with the RVFV MP-12 vaccine strain reduced p62 protein levels to below the detection limit early in the course of infection. This NSs-mediated downregulation of p62 was posttranslational, as it was unaffected by pharmacological inhibition of transcription or translation and MP-12 infection had no effect on p62 mRNA levels. Treatment of cells with proteasome inhibitors but not inhibition of lysosomal acidification or nuclear export resulted in a stabilization of p62 in the presence of NSs. Furthermore, p62 could be coprecipitated with NSs from lysates of infected cells. These data suggest that the RVFV NSs protein is able to interact with the TFIIH subunit p62 inside infected cells and promotes its degradation, which can occur directly in the nucleus. PMID:21543505

Origin of three-armed rifts in volcanic islands: the case of El Hierro (Canary Islands)

Science.gov (United States)

Galindo Jiménez, Inés; Becerril Carretero, Laura; Martí Molist, Joan; Gudmundsson, Agust

2015-04-01

Rifts zones in volcanic oceanic islands are common structures that have been explained through several theories/models. However, despite all these models it is as yet unclear whether it is the intense intrusive activity or the sector collapses that actually control the structural evolution and geometry of oceanic-island rift zones. Here we provide a new hypothesis to explain the origin and characteristics of the feeding system of oceanic-island rift zones based on the analysis of more than 1700 surface, subsurface (water galleries), and submarine structural data from El Hierro (Canary Islands). El Hierro's geological structure is primarily controlled by a three-armed rift-zone, the arms striking NE, WSW and S. Between the rift axes there are three valleys formed during huge landslides: El Golfo, El Julan, and Las Playas. Our results show: (1) a predominant NE-SW strike of structural elements, which coincides with the main regional trend of the Canary Archipelago as a whole; (2) a clear radial strike distribution of structural elements for the whole volcanic edifice (including submarine flanks) with respect to the centre of the island; (3) that the rift zones are mainly subaerial structures and do not propagate through the submarine edifice; (4) that it is only in the NE rift that structures have a general strike similar to that of the rift as a whole, and; (5) that in the W and S rifts there is not clear main direction, showing the structural elements in the W rift a fan distribution coinciding with the general radial pattern in the island as a whole. Based on these data, we suggest that the radial-striking structures reflect comparatively uniform stress fields that operated during the constructive episodes, mainly conditioned by the combination of overburden pressure, gravitational spreading, and magma-induced stresses. By contrast, in the shallower parts of the edifice, that is, the NE-SW, N-S and WNW-ESE-striking structures, reflect local stress fields related

High-Resolution Body Wave Tomography of the Ross Sea Embayment, Antarctica

Science.gov (United States)

White-Gaynor, A.; Nyblade, A.; Wiens, D. A.; Aster, R. C.; Gerstoft, P.; Bromirski, P. D.; Stephen, R. A.

2017-12-01

The West Antarctic Rift System (WARS) is one of the least understood continental rift system on the planet. The 1000 km wide WARS includes the Ross Sea Embayment between Marie Byrd Land and the Transantarctic Mountains (TAMS). Active volcanism on Ross Island continues to challenge our understanding of the generally quiescent rift system. Previous regional-scale body wave tomographic investigations have identified areas of low seismic wave speeds to 200 km depth beneath Ross Island. However, the spatial extent of the low velocity structure across the entirety of the WARS remains poorly constrained due to the insufficient resolution of upper mantle structure under the Ross Sea Embayment away from Ross Island. We utilize teleseismic P wave observations recorded on the RIS/DRIS network, which consists of 34 seismometers deployed across the Ross Ice Shelf, along with data from nearby POLENET and TAMSEIS stations to better resolve this region. Relative P wave travel time residuals from 1300 teleseismic events, obtained using a multichannel cross-correlation method, have been inverted for a seismic velocity model of the upper mantle throughout the Ross Sea Embayment. Our results suggest that the low wave speed structure under Ross Island extends roughly halfway across the Embayment and south along the Transantarctic Mountains. This observation is consistent with a two-phase rifting history for the WARS in which broad, late Cretaceous rifting between Marie Byrd Land and the TAMS transitioned to more focused rifting along the TAMS margin in the Cenozoic.

Genetic Evidence for an Interferon-Antagonistic Function of Rift Valley Fever Virus Nonstructural Protein NSs

Science.gov (United States)

Bouloy, Michèle; Janzen, Christian; Vialat, Pierre; Khun, Huot; Pavlovic, Jovan; Huerre, Michel; Haller, Otto

2001-01-01

Rift Valley fever virus (RVFV), a phlebovirus of the family Bunyaviridae, is a major public health threat in Egypt and sub-Saharan Africa. The viral and host cellular factors that contribute to RVFV virulence and pathogenicity are still poorly understood. All pathogenic RVFV strains direct the synthesis of a nonstructural phosphoprotein (NSs) that is encoded by the smallest (S) segment of the tripartite genome and has an undefined accessory function. In this report, we show that MP12 and clone 13, two attenuated RVFV strains with mutations in the NSs gene, were highly virulent in IFNAR−/− mice lacking the alpha/beta interferon (IFN-α/β) receptor but remained attenuated in IFN-γ receptor-deficient mice. Both attenuated strains proved to be excellent inducers of early IFN-α/β production. In contrast, the virulent strain ZH548 failed to induce detectable amounts of IFN-α/β and replicated extensively in both IFN-competent and IFN-deficient mice. Clone 13 has a defective NSs gene with a large in-frame deletion. This defect in the NSs gene results in expression of a truncated protein which is rapidly degraded. To investigate whether the presence of the wild-type NSs gene correlated with inhibition of IFN-α/β production, we infected susceptible IFNAR−/− mice with S gene reassortant viruses. When the S segment of ZH548 was replaced by that of clone 13, the resulting reassortants became strong IFN inducers. When the defective S segment of clone 13 was exchanged with the wild-type S segment of ZH548, the reassortant virus lost the capacity to stimulate IFN-α/β production. These results demonstrate that the ability of RVFV to inhibit IFN-α/β production correlates with viral virulence and suggest that the accessory protein NSs is an IFN antagonist. PMID:11152510

The use of Nanotrap particles in the enhanced detection of Rift Valley fever virus nucleoprotein.

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Nazly Shafagati

Full Text Available Rift Valley fever virus (RVFV is a highly pathogenic arthropod-borne virus that has a detrimental effect on both livestock and human populations. While there are several diagnostic methodologies available for RVFV detection, many are not sensitive enough to diagnose early infections. Furthermore, detection may be hindered by high abundant proteins such as albumin. Previous findings have shown that Nanotrap particles can be used to significantly enhance detection of various small analytes of low abundance. We have expanded upon this repertoire to show that this simple and efficient sample preparation technology can drastically improve the detection of the RVFV nucleoprotein (NP, the most abundant and widely used viral protein for RVFV diagnostics.After screening multiple Nanotrap particle architectures, we found that one particle, NT45, was optimal for RVFV NP capture, as demonstrated by western blotting. NT45 significantly enhanced detection of the NP at levels undetectable without the technology. Importantly, we demonstrated that Nanotrap particles are capable of concentrating NP in a number of matrices, including infected cell lysates, viral supernatants, and animal sera. Specifically, NT45 enhanced detection of NP at various viral titers, multiplicity of infections, and time points. Our most dramatic results were observed in spiked serum samples, where high abundance serum proteins hindered detection of NP without Nanotrap particles. Nanotrap particles allowed for sample cleanup and subsequent detection of RVFV NP. Finally, we demonstrated that incubation of our samples with Nanotrap particles protects the NP from degradation over extended periods of time (up to 120 hours and at elevated temperatures (at 37ºC.This study demonstrates that Nanotrap particles are capable of drastically lowering the limit of detection for RVFV NP by capturing, concentrating, and preserving RVFV NP in clinically relevant matrices. These studies can be extended to

A temperature-limited assessment of the risk of Rift Valley fever transmission and establishment in the continental United States of America

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Sarah K. Konrad

2012-05-01

Full Text Available The rapid spread of West Nile virus across North America after its introduction in 1999 highlights the potential for foreign arboviruses to become established in the United States of America. Of particular concern is Rift Valley fever virus (RVFV, which has been responsible for multiple African epidemics resulting in death of both humans and livestock, as well as major economic disruption due to livestock loss and trade restrictions. Modern globalization, travel, and commerce allow viruses to easily jump from one continent to another; and it is likely only a matter of time before RVFV reaches North American shores. We used a degree-day model in combination with livestock population data and a pathways analysis to identify regions and times where RVFV is most likely to enter and become established in the United States of America. Transmission risk of the disease varies across the country from 325 annual risk days in parts of Florida to zero risk days in the far North and in high mountain regions. Areas of particular concern are where there are a high number of possible transmission days, a large livestock population, and proximity to likely locations for the disease to enter the country via mosquito vector or human host. These areas should be monitored closely during transmission “risk seasons” so that if the virus does enter the country and begins to become established, it can be quickly controlled and eliminated before spreading further. Areas most at risk include the Baltimore and New York City metro areas as well as much of the region between these urban centers; most of Texas, especially around Houston; Florida; Atlanta; southwest Nebraska; southern California and Arizona; and the central valley of California.

Co-housing of Rift Valley fever virus infected lambs with immunocompetent or immunosuppressed lambs does not result in virus transmission

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Paul J Wichgers Schreur

2016-03-01

Full Text Available Rift Valley fever virus (RVFV is transmitted among susceptible animals by mosquito vectors. Although the virus can be isolated from nasal and oral swabs of infected animals and is known to be highly infectious when administered experimentally via oral or respiratory route, horizontal transmission of the virus is only sporadically reported in literature. We considered that immunosuppression resulting from stressful conditions in the field may increase the susceptibility to horizontally transmitted RVFV. Additionally, we reasoned that horizontal transmission may induce immune responses that could affect the susceptibility of contact-exposed animals to subsequent infection via mosquito vectors. To address these two hypotheses, viremic lambs were brought into contact with sentinel lambs. One group of sentinel lambs was treated with the immunosuppressive synthetic glucocorticosteroid dexamethasone and monitored for signs of disease and presence of virus in the blood and target organs. Another group of contact-exposed sentinel lambs remained untreated for three weeks and was subsequently challenged with RVFV. We found that none of the dexamethasone-treated contact-exposed lambs developed detectable viremia, antibody responses or significant increases in cytokine mRNA levels. Susceptibility of immunocompetent lambs to RVFV infection was not influenced by previous contact-exposure. Our results are discussed in light of previous findings.

NSs protein of severe fever with thrombocytopenia syndrome virus suppresses interferon production through different mechanism than Rift Valley fever virus.

Science.gov (United States)

Zhang, S; Zheng, B; Wang, T; Li, A; Wan, J; Qu, J; Li, C H; Li, D; Liang, M

Severe fever with thrombocytopenia syndrome virus (SFTSV) is a newly identified Phlebovirus that causes severe fever with thrombocytopenia syndrome. Our study demonstrated that SFTSV NSs functioned as IFN antagonist mainly by suppressing TBK1/IKKε-IRF3 signaling pathway. NSs interacted with and relocalized TANK-binding kinase 1 (TBK1) into NSs-induced cytoplasmic structures and this interaction could effectively inhibit downstream phosphorylation and dimerization of interferon regulatory factor 3 (IRF3), resulting in the suppression of antiviral signaling and IFN induction. Functional sites of SFTSV NSs binding with TBK1 were then studied and results showed that NSs had lost their IFN-inhibiting activity after deleting the 25 amino acids in N-terminal. Furthermore, the mechanism of Rift Valley fever virus (RVFV) NSs blocking IFN-β response were also investigated. Preliminary results showed that RVFV NSs proteins could neither interact nor co-localize with TBK1 in cytoplasm, but suppressed its expression levels, phosphorylation and dimerization of IRF3 in the subsequent steps, resulting in inhibition of the IFN-β production. Altogether, our data demonstrated the probable mechanism used by SFTSV to inhibit IFN responses which was different from RVFV and pointed toward a novel mechanism for RVFV suppressing IFN responses.

Twenty-five years of geodetic measurements along the Tadjoura-Asal rift system, Djibouti, East Africa

Science.gov (United States)

Vigny, Christophe; de Chabalier, Jean-Bernard; Ruegg, Jean-Claude; Huchon, Philippe; Feigl, Kurt L.; Cattin, Rodolphe; Asfaw, Laike; Kanbari, Khaled

2007-06-01

Since most of Tadjoura-Asal rift system sits on dry land in the Afar depression near the triple junction between the Arabia, Somalia, and Nubia plates, it is an ideal natural laboratory for studying rifting processes. We analyze these processes in light of a time series of geodetic measurements from 1978 through 2003. The surveys used triangulation (1973), trilateration (1973, 1979, and 1981-1986), leveling (1973, 1979, 1984-1985, and 2000), and the Global Positioning System (GPS, in 1991, 1993, 1995, 1997, 1999, 2001, and 2003). A network of about 30 GPS sites covers the Republic of Djibouti. Additional points were also measured in Yemen and Ethiopia. Stations lying in the Danakil block have almost the same velocity as Arabian plate, indicating that opening near the southern tip of the Red Sea is almost totally accommodated in the Afar depression. Inside Djibouti, the Asal-Ghoubbet rift system accommodates 16 ± 1 mm/yr of opening perpendicular to the rift axis and exhibits a pronounced asymmetry with essentially null deformation on its southwestern side and significant deformation on its northeastern side. This rate, slightly higher than the large-scale Arabia-Somalia motion (13 ± 1 mm/yr), suggests transient variations associated with relaxation processes following the Asal-Ghoubbet seismovolcanic sequence of 1978. Inside the rift, the deformation pattern exhibits a clear two-dimensional pattern. Along the rift axis, the rate decreases to the northwest, suggesting propagation in the same direction. Perpendicular to the rift axis, the focus of the opening is clearly shifted to the northeast, relative to the topographic rift axis, in the "Petit Rift," a rift-in-rift structure, containing most of the active faults and the seismicity. Vertical motions, measured by differential leveling, show the same asymmetric pattern with a bulge of the northeastern shoulder. Although the inner floor of the rift is subsiding with respect to the shoulders, all sites within the

The distribution and hydrogeological controls of fluoride in the groundwater of central Ethiopian rift and adjacent highlands

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Ayenew, Tenalem

2008-05-01

Occurrence of fluoride (F) in groundwater has drawn worldwide attention, since it has considerable impact on human health. In Ethiopia high concentrations of F in groundwaters used for community water supply have resulted in extensive dental and skeletal fluorosis. As a part of a broader study, the distribution of F in groundwater has been investigated, and compared with bedrock geology and pertinent hydrochemical variables. The result indicates extreme spatial variations. High F concentration is often associated with active and sub-active regional thermal fields and acidic volcanics within high temperature rift floor. Variations in F can also be related to changes in calcium concentration resulting from dissolution of calcium minerals and mixing with waters of different chemical composition originated from variable hydrogeological environment across the rift valley. The concentration of F dramatically declines from the rift towards the highlands with the exception of scattered points associated with thermal springs confined in local volcanic centers. There are also interactions of F-rich alkaline lakes and the surrounding groundwater. Meteoric waters recharging volcanic aquifers become enriched with respect to F along the groundwater flow path from highland recharge areas to rift discharge areas. Locally wells drilled along large rift faults acting as conduits of fresh highland waters show relatively lower F. These areas are likely to be possible sources of better quality waters within the rift. The result of this study has important implications on site selection for water well drilling.

Present-day kinematics of the Danakil block (southern Red Sea-Afar) constrained by GPS

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Ladron de Guevara, R.; Jonsson, S.; Ruch, J.; Doubre, C.; Reilinger, R. E.; Ogubazghi, G.; Floyd, M.; Vasyura-Bathke, H.

2017-12-01

The rifting of the Arabian plate from the Nubian and Somalian plates is primarily accommodated by seismic and magmatic activity along two rift arms of the Afar triple junction (the Red Sea and Gulf of Aden rifts). The spatial distribution of active deformation in the Afar region have been constrained with geodetic observations. However, the plate boundary configuration in which this deformation occurs is still not fully understood. South of 17°N, the Red Sea rift is composed of two parallel and overlapping rift branches separated by the Danakil block. The distribution of the extension across these two overlapping rifts, their potential connection through a transform fault zone and the counterclockwise rotation of the Danakil block have not yet been fully resolved. Here we analyze new GPS observations from the Danakil block, the Gulf of Zula area (Eritrea) and Afar (Ethiopia) together with previous geodetic survey data to better constrain the plate kinematics and active deformation of the region. The new data has been collected in 2016 and add up to 5 years to the existing geodetic observations (going back to 2000). Our improved GPS velocity field shows differences with previously modeled GPS velocities, suggesting that the rate and rotation of the Danakil block need to be updated. The new velocity field also shows that the plate-boundary strain is accommodated by broad deformation zones rather than across sharp boundaries between tectonic blocks. To better determine the spatial distribution of the strain, we first implement a rigid block model to constrain the overall regional plate kinematics and to isolate the plate-boundary deformation at the western boundary of the Danakil block. We then study whether the recent southern Red Sea rifting events have caused detectable changes in observed GPS velocities and if the observations can be used to constrain the scale of this offshore rift activity. Finally, we investigate different geometries of transform faults that

Numerical analysis of air pollution in a combined field of land/sea breeze and mountain/valley wind

International Nuclear Information System (INIS)

Kitada, T.; Igarashi, K.; Owada, M.

1986-01-01

Air pollution in the presence of two types of local flows (i.e., land/sea breeze and mountain/valley wind) was studies by advection simulation of the cluster of hypothetical fluid particles, and transport/chemistry calculation employing a three-dimensional Eulerian model for 20 advected species and about 90 chemical reactions. Three-dimensional flow fields over the River Yahagi basin in Japan were estimated for 48 h using an objective method with routine wind observations. Those obtained showed characteristics of the combined local flows such that in the daytime sea breeze and valley wind tend to form one united flow with substantial wind velocity in the whole region and, in contrast, land breeze and mountain wind during the nighttime form two separated circulating flows with a clear weak-wind area between the two local flow regimes. The results of the advection simulation of fluid particles and the transport/chemistry calculation using those flows as inputs elucidated how the features found in the diurnally varying, complex local flows contribute to produce characteristic time-variations of the concentrations of both primary and secondary pollutants. Among others, dynamics of NO 2 , HNO 3 , PAN, O 3 , SO 2 , and SO 4 /sup =/ concentrations are discussed

Distinct virulence of Rift Valley fever phlebovirus strains from different genetic lineages in a mouse model.

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Tetsuro Ikegami

Full Text Available Rift Valley fever phlebovirus (RVFV causes high rates of abortions and fetal malformations in ruminants, and hemorrhagic fever, encephalitis, or blindness in humans. Viral transmission occurs via mosquito vectors in endemic areas, which necessitates regular vaccination of susceptible livestock animals to prevent the RVF outbreaks. Although ZH501 strain has been used as a challenge strain for past vaccine efficacy studies, further characterization of other RVFV strains is important to optimize ruminant and nonhuman primate RVFV challenge models. This study aimed to characterize the virulence of wild-type RVFV strains belonging to different genetic lineages in outbred CD1 mice. Mice were intraperitoneally infected with 1x103 PFU of wild-type ZH501, Kenya 9800523, Kenya 90058, Saudi Arabia 200010911, OS1, OS7, SA75, Entebbe, or SA51 strains. Among them, mice infected with SA51, Entebbe, or OS7 strain showed rapid dissemination of virus in livers and peracute necrotic hepatitis at 2-3 dpi. Recombinant SA51 (rSA51 and Zinga (rZinga strains were recovered by reverse genetics, and their virulence was also tested in CD1 mice. The rSA51 strain reproduced peracute RVF disease in mice, whereas the rZinga strain showed a similar virulence with that of rZH501 strain. This study showed that RVFV strains in different genetic lineages display distinct virulence in outbred mice. Importantly, since wild-type RVFV strains contain defective-interfering RNA or various genetic subpopulations during passage from original viral isolations, recombinant RVFV strains generated by reverse genetics will be better suitable for reproducible challenge studies for vaccine development as well as pathological studies.

Characterising and comparing animal-health services in the Rift Valley, Kenya: an exploratory analysis (part I).

Science.gov (United States)

Higham, L E; Ongeri, W; Asena, K; Thrusfield, M V

2016-12-01

Livestock are of vital importance to the livelihoods of millions of people across the world, playing a pivotal role in income generation, employment, food security, transport and social cohesion. Access to quality animal-health services by livestock owners is critical to sustainable food-animal production; therefore, animal-health practitioners represent key stakeholders within the world food system. A mixed-method study was conducted in the Rift Valley of Kenya to characterise and compare existing private animal-health services and to explore perceptions of veterinary services amongst pastoralists and farmers. Forty structured questionnaires were administered to staff at animal-health outlets, including franchise outlets of 'Sidai Africa Ltd.', and two focus group discussions were facilitated to explore the perceptions of a Maasai pastoralist group and members of a dairy-farmer cooperative of their local animal-health services. Results were analysed using descriptive methods and the confidence interval overlap technique. Differences were detected in the characteristics of Sidai outlets, agrovets (agricultural retailers), pharmacies and dukas (general shops). Sidai outlets offered a more professional and diverse portfolio of livestock services. Across all outlet types, staff knowledge and training gaps and a shortage of cold-chain facilities were identified. Farmers have strong preferences for certain products, which may foster the development of drug resistance. There is a disconnection between the sale of veterinary medicines and the provision of quality advice, with many agrovets, pharmacies and dukas selling veterinary medicines but lacking the capacity to provide clinical services. There is a clear demand from livestock keepers for accessible, affordable and quality animal-health services and products in Kenya; therefore, animal-health practitioners have the potential to provide increased support to livestock-based livelihoods.

Modelling the effects of seasonality and socioeconomic impact on the transmission of Rift Valley fever virus

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Xiao, Yanyu; Beier, John C.; Cantrell, Robert Stephen; Cosner, Chris; DeAngelis, Donald L.; Ruan, Shigui

2015-01-01

Rift Valley fever (RVF) is an important mosquito-borne viral zoonosis in Africa and the Middle East that causes human deaths and significant economic losses due to huge incidences of death and abortion among infected livestock. Outbreaks of RVF are sporadic and associated with both seasonal and socioeconomic effects. Here we propose an almost periodic three-patch model to investigate the transmission dynamics of RVF virus (RVFV) among ruminants with spatial movements. Our findings indicate that, in Northeastern Africa, human activities, including those associated with the Eid al Adha feast, along with a combination of climatic factors such as rainfall level and hydrological variations, contribute to the transmission and dispersal of the disease pathogen. Moreover, sporadic outbreaks may occur when the two events occur together: 1) abundant livestock are recruited into areas at risk from RVF due to the demand for the religious festival and 2) abundant numbers of mosquitoes emerge. These two factors have been shown to have impacts on the severity of RVF outbreaks. Our numerical results present the transmission dynamics of the disease pathogen over both short and long periods of time, particularly during the festival time. Further, we investigate the impact on patterns of disease outbreaks in each patch brought by festival- and seasonal-driven factors, such as the number of livestock imported daily, the animal transportation speed from patch to patch, and the death rate induced by ceremonial sacrifices. In addition, our simulations show that when the time for festival preparation starts earlier than usual, the risk of massive disease outbreaks rises, particularly in patch 3 (the place where the religious ceremony will be held).

The nonstructural protein NSs induces a variable antibody response in domestic ruminants naturally infected with Rift Valley fever virus.

Science.gov (United States)

Fernandez, José-Carlos; Billecocq, Agnès; Durand, Jean Paul; Cêtre-Sossah, Catherine; Cardinale, Eric; Marianneau, Philippe; Pépin, Michel; Tordo, Noël; Bouloy, Michèle

2012-01-01

Rift Valley fever (RVF) is an emerging zoonosis in Africa which has spread to Egypt, the Arabian Peninsula, Madagascar, and Comoros. RVF virus (RVFV) (Bunyaviridae family, Phlebovirus genus) causes a wide range of symptoms in humans, from benign fever to fatal hemorrhagic fever. Ruminants are severely affected by the disease, which leads to a high rate of mortality in young animals and to abortions and teratogenesis in pregnant females. Diagnostic tests include virus isolation and genome or antibody detection. During RVFV infection, the nucleoprotein encapsidating the tripartite RNA genome is expressed in large amounts and raises a robust antibody response, while the envelope glycoproteins elicit neutralizing antibodies which play a major role in protection. Much less is known about the antigenicity/immunogenicity of the nonstructural protein NSs, which is a major virulence factor. Here we have developed a competitive enzyme-linked immunosorbent assay (ELISA) enabling detection of low levels of NSs-specific antibodies in naturally infected or vaccinated ruminants. Detection of the NSs antibodies was validated by Western blotting. Altogether, our data showed that the NSs antibodies were detected in only 55% of animals naturally infected by RVFV, indicating that NSs does not induce a consistently high immune response. These results are discussed in light of differentiation between infected and vaccinated animals (DIVA) tests distinguishing naturally infected animals and those vaccinated with NSs-defective vaccines.

TerraSAR-X high-resolution radar remote sensing: an operational warning system for Rift Valley fever risk.

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Vignolles, Cécile; Tourre, Yves M; Mora, Oscar; Imanache, Laurent; Lafaye, Murielle

2010-11-01

In the vicinity of the Barkedji village (in the Ferlo region of Senegal), the abundance and aggressiveness of the vector mosquitoes for Rift Valley fever (RVF) are strongly linked to rainfall events and associated ponds dynamics. Initially, these results were obtained from spectral analysis of high-resolution (~10 m) Spot-5 images, but, as a part of the French AdaptFVR project, identification of the free water dynamics within ponds was made with the new high-resolution (down to 3-meter pixels), Synthetic Aperture Radar satellite (TerraSAR-X) produced by Infoterra GmbH, Friedrichshafen/Potsdam, Germany. During summer 2008, within a 30 x 50 km radar image, it was found that identified free water fell well within the footprints of ponds localized by optical data (i.e. Spot-5 images), which increased the confidence in this new and complementary remote sensing technique. Moreover, by using near real-time rainfall data from the Tropical Rainfall Measuring Mission (TRMM), NASA/JAXA joint mission, the filling-up and flushing-out rates of the ponds can be accurately determined. The latter allows for a precise, spatio-temporal mapping of the zones potentially occupied by mosquitoes capable of revealing the variability of pond surfaces. The risk for RVF infection of gathered bovines and small ruminants (~1 park/km(2)) can thus be assessed. This new operational approach (which is independent of weather conditions) is an important development in the mapping of risk components (i.e. hazards plus vulnerability) related to RVF transmission during the summer monsoon, thus contributing to a RVF early warning system.

Predicting Rift Valley Fever Inter-epidemic Activities and Outbreak Patterns: Insights from a Stochastic Host-Vector Model.

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Sansao A Pedro

2016-12-01

Full Text Available Rift Valley fever (RVF outbreaks are recurrent, occurring at irregular intervals of up to 15 years at least in East Africa. Between outbreaks disease inter-epidemic activities exist and occur at low levels and are maintained by female Aedes mcintoshi mosquitoes which transmit the virus to their eggs leading to disease persistence during unfavourable seasons. Here we formulate and analyse a full stochastic host-vector model with two routes of transmission: vertical and horizontal. By applying branching process theory we establish novel relationships between the basic reproduction number, R0, vertical transmission and the invasion and extinction probabilities. Optimum climatic conditions and presence of mosquitoes have not fully explained the irregular oscillatory behaviour of RVF outbreaks. Using our model without seasonality and applying van Kampen system-size expansion techniques, we provide an analytical expression for the spectrum of stochastic fluctuations, revealing how outbreaks multi-year periodicity varies with the vertical transmission. Our theory predicts complex fluctuations with a dominant period of 1 to 10 years which essentially depends on the efficiency of vertical transmission. Our predictions are then compared to temporal patterns of disease outbreaks in Tanzania, Kenya and South Africa. Our analyses show that interaction between nonlinearity, stochasticity and vertical transmission provides a simple but plausible explanation for the irregular oscillatory nature of RVF outbreaks. Therefore, we argue that while rainfall might be the major determinant for the onset and switch-off of an outbreak, the occurrence of a particular outbreak is also a result of a build up phenomena that is correlated to vertical transmission efficiency.

TerraSAR-X high-resolution radar remote sensing: an operational warning system for Rift Valley fever risk

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Cécile Vignolles

2010-11-01

Full Text Available In the vicinity of the Barkedji village (in the Ferlo region of Senegal, the abundance and aggressiveness of the vector mosquitoes for Rift Valley fever (RVF are strongly linked to rainfall events and associated ponds dynamics. Initially, these results were obtained from spectral analysis of high-resolution (~10 m Spot-5 images, but, as a part of the French AdaptFVR project, identification of the free water dynamics within ponds was made with the new high-resolution (down to 3-meter pixels, Synthetic Aperture Radar satellite (TerraSAR-X produced by Infoterra GmbH, Friedrichshafen/Potsdam, Germany. During summer 2008, within a 30 x 50 km radar image, it was found that identified free water fell well within the footprints of ponds localized by optical data (i.e. Spot-5 images, which increased the confidence in this new and complementary remote sensing technique. Moreover, by using near real-time rainfall data from the Tropical Rainfall Measuring Mission (TRMM, NASA/JAXA joint mission, the filling-up and flushingout rates of the ponds can be accurately determined. The latter allows for a precise, spatio-temporal mapping of the zones potentially occupied by mosquitoes capable of revealing the variability of pond surfaces. The risk for RVF infection of gathered bovines and small ruminants (~1 park/km2 can thus be assessed. This new operational approach (which is independent of weather conditions is an important development in the mapping of risk components (i.e. hazards plus vulnerability related to RVF transmission during the summer monsoon, thus contributing to a RVF early warning system.

Rift valley fever virus nonstructural protein NSs promotes viral RNA replication and transcription in a minigenome system.

Science.gov (United States)

Ikegami, Tetsuro; Peters, C J; Makino, Shinji

2005-05-01

Rift Valley fever virus (RVFV), which belongs to the genus Phlebovirus, family Bunyaviridae, has a tripartite negative-strand genome (S, M, and L segments) and is an important mosquito-borne pathogen for domestic animals and humans. We established an RVFV T7 RNA polymerase-driven minigenome system in which T7 RNA polymerase from an expression plasmid drove expression of RNA transcripts for viral proteins and minigenome RNA transcripts carrying a reporter gene between both termini of the M RNA segment in 293T cells. Like other viruses of the Bunyaviridae family, replication and transcription of the RVFV minigenome required expression of viral N and L proteins. Unexpectedly, the coexpression of an RVFV nonstructural protein, NSs, with N and L proteins resulted in a significant enhancement of minigenome RNA replication. Coexpression of NSs protein with N and L proteins also enhanced minigenome mRNA transcription in the cells expressing viral-sense minigenome RNA transcripts. NSs protein expression increased the RNA replication of minigenomes that originated from S and L RNA segments. Enhancement of minigenome RNA synthesis by NSs protein occurred in cells lacking alpha/beta interferon (IFN-alpha/beta) genes, indicating that the effect of NSs protein on minigenome RNA replication was unrelated to a putative NSs protein-induced inhibition of IFN-alpha/beta production. Our finding that RVFV NSs protein augmented minigenome RNA synthesis was in sharp contrast to reports that Bunyamwera virus (genus Bunyavirus) NSs protein inhibits viral minigenome RNA synthesis, suggesting that RVFV NSs protein and Bunyamwera virus NSs protein have distinctly different biological roles in viral RNA synthesis.

Rift Valley fever dynamics in Senegal: a project for pro-active adaptation and improvement of livestock raising management

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Murielle Lafaye

2013-11-01

Full Text Available The multi-disciplinary French project “Adaptation à la Fièvre de la Vallée du Rift” (AdaptFVR has concluded a 10-year constructive interaction between many scientists/partners involved with the Rift Valley fever (RVF dynamics in Senegal. The three targeted objectives reached were (i to produce - in near real-time - validated risk maps for parked livestock exposed to RVF mosquitoes/vectors bites; (ii to assess the impacts on RVF vectors from climate variability at different time-scales including climate change; and (iii to isolate processes improving local livestock management and animal health. Based on these results, concrete, pro-active adaptive actions were taken on site, which led to the establishment of a RVF early warning system (RVFews. Bulletins were released in a timely fashion during the project, tested and validated in close collaboration with the local populations, i.e. the primary users. Among the strategic, adaptive methods developed, conducted and evaluated in terms of cost/benefit analyses are the larvicide campaigns and the coupled bio-mathematical (hydrological and entomological model technologies, which are being transferred to the staff of the “Centre de Suivi Ecologique” (CSE in Dakar during 2013. Based on the results from the AdaptFVR project, other projects with similar conceptual and modelling approaches are currently being implemented, e.g. for urban and rural malaria and dengue in the French Antilles.

Dietary Fluoride Intake and Associated Skeletal and Dental Fluorosis in School Age Children in Rural Ethiopian Rift Valley

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Aweke Kebede

2016-07-01

Full Text Available An observational study was conducted to determine dietary fluoride intake, diet, and prevalence of dental and skeletal fluorosis of school age children in three fluorosis endemic districts of the Ethiopian Rift Valley having similar concentrations of fluoride (F in drinking water (~5 mg F/L. The duplicate plate method was used to collect foods consumed by children over 24 h from 20 households in each community (n = 60 and the foods, along with water and beverages, were analyzed for fluoride (F content. Prevalence of dental and skeletal fluorosis was determined using presence of clinical symptoms in children (n = 220. Daily dietary fluoride intake was at or above tolerable upper intake level (UL of 10 mg F/day and the dietary sources (water, prepared food and beverages all contributed to the daily fluoride burden. Urinary fluoride in children from Fentale and Adamitulu was almost twice (>5 mg/L the concentration found in urine from children from Alaba, where rain water harvesting was most common. Severe and moderate dental fluorosis was found in Alaba and Adamitulu, the highest severity and prevalence being in the latter district where staple foods were lowest in calcium. Children in all three areas showed evidence of both skeletal and non-skeletal fluorosis. Our data support the hypothesis that intake of calcium rich foods in addition to using rain water for household consumption and preparation of food, may help in reducing risk of fluorosis in Ethiopia, but prospective studies are needed.

Is the Proterozoic Ladoga Rift (SE Baltic Shield) a rift?

DEFF Research Database (Denmark)

Artemieva, Irina; Shulgin, Alexey

2015-01-01

, and geophysical characteristics typical of continental rifts in general and demonstrate that, except for magmatic and, perhaps, some gravity signature, the Lake Ladoga region lacks any other rift features. We also compare the geophysical data from the Lake Ladoga region with similar in age Midcontinent and Valday...... interpreted as an intracratonic Ladoga rift (graben). We question the validity of this geodynamic interpretation by analyzing regional geophysical data (crustal structure, heat flow, Bouguer gravity anomalies, magnetic anomalies, and mantle Vs velocities). We provide a complete list of tectonic, magmatic...... rifts, and provide alternative explanations for Mesoproterozoic geodynamic evolution of the southern Baltic Shield. We propose that Mesoproterozoic mafic intrusions in southern Fennoscandia may be associated with a complex deformation pattern during reconfiguration of (a part of) Nuna (Columbia...

Combining hydrology and mosquito population models to identify the drivers of Rift Valley fever emergence in semi-arid regions of West Africa.

Science.gov (United States)

Soti, Valérie; Tran, Annelise; Degenne, Pascal; Chevalier, Véronique; Lo Seen, Danny; Thiongane, Yaya; Diallo, Mawlouth; Guégan, Jean-François; Fontenille, Didier

2012-01-01

Rift Valley fever (RVF) is a vector-borne viral zoonosis of increasing global importance. RVF virus (RVFV) is transmitted either through exposure to infected animals or through bites from different species of infected mosquitoes, mainly of Aedes and Culex genera. These mosquitoes are very sensitive to environmental conditions, which may determine their presence, biology, and abundance. In East Africa, RVF outbreaks are known to be closely associated with heavy rainfall events, unlike in the semi-arid regions of West Africa where the drivers of RVF emergence remain poorly understood. The assumed importance of temporary ponds and rainfall temporal distribution therefore needs to be investigated. A hydrological model is combined with a mosquito population model to predict the abundance of the two main mosquito species (Aedes vexans and Culex poicilipes) involved in RVFV transmission in Senegal. The study area is an agropastoral zone located in the Ferlo Valley, characterized by a dense network of temporary water ponds which constitute mosquito breeding sites. The hydrological model uses daily rainfall as input to simulate variations of pond surface areas. The mosquito population model is mechanistic, considers both aquatic and adult stages and is driven by pond dynamics. Once validated using hydrological and entomological field data, the model was used to simulate the abundance dynamics of the two mosquito species over a 43-year period (1961-2003). We analysed the predicted dynamics of mosquito populations with regards to the years of main outbreaks. The results showed that the main RVF outbreaks occurred during years with simultaneous high abundances of both species. Our study provides for the first time a mechanistic insight on RVFV transmission in West Africa. It highlights the complementary roles of Aedes vexans and Culex poicilipes mosquitoes in virus transmission, and recommends the identification of rainfall patterns favourable for RVFV amplification.

Combining hydrology and mosquito population models to identify the drivers of Rift Valley fever emergence in semi-arid regions of West Africa.

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Valérie Soti

Full Text Available BACKGROUND: Rift Valley fever (RVF is a vector-borne viral zoonosis of increasing global importance. RVF virus (RVFV is transmitted either through exposure to infected animals or through bites from different species of infected mosquitoes, mainly of Aedes and Culex genera. These mosquitoes are very sensitive to environmental conditions, which may determine their presence, biology, and abundance. In East Africa, RVF outbreaks are known to be closely associated with heavy rainfall events, unlike in the semi-arid regions of West Africa where the drivers of RVF emergence remain poorly understood. The assumed importance of temporary ponds and rainfall temporal distribution therefore needs to be investigated. METHODOLOGY/PRINCIPAL FINDINGS: A hydrological model is combined with a mosquito population model to predict the abundance of the two main mosquito species (Aedes vexans and Culex poicilipes involved in RVFV transmission in Senegal. The study area is an agropastoral zone located in the Ferlo Valley, characterized by a dense network of temporary water ponds which constitute mosquito breeding sites. The hydrological model uses daily rainfall as input to simulate variations of pond surface areas. The mosquito population model is mechanistic, considers both aquatic and adult stages and is driven by pond dynamics. Once validated using hydrological and entomological field data, the model was used to simulate the abundance dynamics of the two mosquito species over a 43-year period (1961-2003. We analysed the predicted dynamics of mosquito populations with regards to the years of main outbreaks. The results showed that the main RVF outbreaks occurred during years with simultaneous high abundances of both species. CONCLUSION/SIGNIFICANCE: Our study provides for the first time a mechanistic insight on RVFV transmission in West Africa. It highlights the complementary roles of Aedes vexans and Culex poicilipes mosquitoes in virus transmission, and recommends

Geothermal energy and hot springs in Ethiopia

Energy Technology Data Exchange (ETDEWEB)

Koga, T. (Hot Springs Therapeutics Research Institute, Kyushu, Univ., Japan)

1971-01-01

The hot springs in Ethiopia are concentrated in two areas: the North Afar depression and adjacent Red Sea shore, and a geothermal field 100 km from northeast to southwest in the central part of Ethiopia. The latter extends not only to the Great Rift Valley but also to the Aden Gulf. In the lake district in the central Great Rift Valley, there are a number of hot springs on the lake shore. These are along NE-SW fault lines, and the water is a sodium bicarbonate-type rich in HCO/sub 3/ and Na but low in C1 and Ca. In Dallol in the North Afar depression, CO/sub 2/-containing hot springs with high temperatures (110/sup 0/C) and a specific gravity of 1.4, were observed. In the South Afar depression, located in the northeastern part of the Rift Valley, there are many active volcanoes and hot springs between the lake district and the Danakil depression. The spring water is a sodium bicarbonate saline type. Nine graphs and maps are included.

Continental rift formation and transition to ocean sea floor spreading : A case study of the Afar triple junction

NARCIS (Netherlands)

Lavecchia, A.L.

2017-01-01

Lithosphere extension, thinning and breakup are fundamental processes in geodynamics. During rift development, both the lithosphere and the mantle are involved in a coupled system, in which the main mechanisms and the forces associated with them often vary during the rift evolution. Furthermore, the

Pathogenic effects of Rift Valley fever virus NSs gene are alleviated in cultured cells by expressed antiviral short hairpin RNAs.

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Scott, Tristan; Paweska, Janusz T; Arbuthnot, Patrick; Weinberg, Marc S

2012-01-01

Rift Valley fever virus (RVFV), a member of the Bunyaviridae family, may cause severe hepatitis, encephalitis and haemorrhagic fever in humans. There are currently no available licensed vaccines or therapies to treat the viral infection in humans. RNA interference (RNAi)-based viral gene silencing offers a promising approach to inhibiting replication of this highly pathogenic virus. The small (S) segment of the RVFV tripartite genome carries the genetic determinates for pathogenicity during infection. This segment encodes the non-structural S (NSs) and essential nucleocapsid (N) genes. To advance RNAi-based inhibition of RVFV replication, we designed several Pol III short hairpin RNA (shRNA) expression cassettes against the NSs and N genes, including a multimerized plasmid vector that included four shRNA expression cassettes. Effective target silencing was demonstrated using full- and partial-length target reporter assays, and confirmed by western blot analysis of exogenous N and NSs expression. Small RNA northern blots showed detectable RNAi guide strand formation from single and multimerized shRNA constructs. Using a cell culture model of RVFV replication, shRNAs targeting the N gene decreased intracellular nucleocapsid protein concentration and viral replication. The shRNAs directed against the NSs gene reduced NSs protein concentrations and alleviated NSs-mediated cytotoxicity, which may be caused by host transcription suppression. These data are the first demonstration that RNAi activators have a potential therapeutic benefit for countering RVFV infection.

The origin of Mauna Loa's Nīnole Hills: Evidence of rift zone reorganization

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Zurek, Jeffrey; Williams-Jones, Glyn; Trusdell, Frank A.; Martin, Simon

2015-01-01

In order to identify the origin of Mauna Loa volcano's Nīnole Hills, Bouguer gravity was used to delineate density contrasts within the edifice. Our survey identified two residual anomalies beneath the Southwest Rift Zone (SWRZ) and the Nīnole Hills. The Nīnole Hills anomaly is elongated, striking northeast, and in inversions both anomalies merge at approximately −7 km above sea level. The positive anomaly, modeled as a rock volume of ~1200 km3 beneath the Nīnole Hills, is associated with old eruptive vents. Based on the geologic and geophysical data, we propose that the gravity anomaly under the Nīnole Hills records an early SWRZ orientation, now abandoned due to geologically rapid rift-zone reorganization. Catastrophic submarine landslides from Mauna Loa's western flank are the most likely cause for the concurrent abandonment of the Nīnole Hills section of the SWRZ. Rift zone reorganization induced by mass wasting is likely more common than currently recognized.

The Jurassic of Denmark and Greenland: key elements in the reconstruction of the North Atlantic Jurassic rift system

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Surlyk, Finn

2003-10-01

Full Text Available The Jurassic succession of Denmark is largely confined to the subsurface with the exception of exposures on the island of Bornholm in the Baltic Sea. In East Greenland, in contrast, the Jurassic is extensively exposed. Comparison of basin evolution in the two regions, which now occur on two separate plates, thus relies on highly different datasets. It is possible nevertheless to construct an integrated picture allowing testing of hypotheses concerning basin evolution, regional uplift, onset and climax of rifting, relative versus eustatic sea-level changes and sequence stratigraphic subdivision and correlation. On a smaller scale, it is possible to compare the signatures of sequence stratigraphic surfaces as seen on well logs, in cores and at outcrop and of sequences recognised and defined on the basis of very different data types. Breakdown of the successions into tectonostratigraphic megasequences highlights the high degree of similarity in overall basin evolution and tectonic style. An important difference, however, lies in the timing. Major events such as late Early - Middle Jurassic uplift, followed by onset of rifting, basin reorganisation and rift climax were delayed in East Greenland relative to the Danish region. This has important implications both for regional reconstructions of the rift system and for the understanding and testing of classical sequence stratigraphic concepts involving eustatic versus tectonic controls of basin evolution and stratigraphy.

3D Numerical Rift Modeling with Application to the East African Rift System

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Glerum, A.; Brune, S.; Naliboff, J.

2017-12-01

As key components of plate tectonics, continental rifting and the formation of passive margins have been extensively studied with both analogue models and numerical techniques. Only recently however, technical advances have enabled numerical investigations into rift evolution in three dimensions, as is actually required for including those processes that cause rift-parallel variability, such as structural inheritance and oblique extension (Brune 2016). We use the massively parallel finite element code ASPECT (Kronbichler et al. 2012; Heister et al. 2017) to investigate rift evolution. ASPECT's adaptive mesh refinement enables us to focus resolution on the regions of interest (i.e. the rift center), while leaving other areas such as the asthenospheric mantle at coarse resolution, leading to kilometer-scale local mesh resolution in 3D. Furthermore, we implemented plastic and viscous strain weakening of the nonlinear viscoplastic rheology required to develop asymmetric rift geometries (e.g. Huismans and Beaumont 2003). Additionally created plugins to ASPECT allow us to specify initial temperature and composition conditions based on geophysical data (e.g. LITHO1.0, Pasyanos et al. 2014) or to prescribe more general along-strike variation in the initial strain seeding the rift. Employing the above functionality, we construct regional models of the East African Rift System (EARS), the world's largest currently active rift. As the EARS is characterized by both orthogonal and oblique rift sections, multi-phase extension histories as well as magmatic and a-magmatic branches (e.g. Chorowicz 2005; Ebinger and Scholz 2011), it constitutes an extensive natural laboratory for our research into the 3D nature of continental rifting. References:Brune, S. (2016), in Plate boundaries and natural hazards, AGU Geophysical Monograph 219, J. C. Duarte and W. P. Schellart (Eds.). Chorowicz, J. (2005). J. Afr. Earth Sci., 43, 379-410. Ebinger, C. and Scholz, C. A. (2011), in Tectonics of

Mesoscale energetics and flows induced by sea-land and mountain-valley contrasts

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S. Federico

2000-02-01

Full Text Available We study the relative importance of sea-land and mountain-valley thermal contrasts in determining the development of thermally forced mesoscale circulations (TFMCs over a mountainous peninsula. We first analyse the energetics of the problem, and using this theory, we interprete the numerical simulations over Calabria, a mountainous peninsula in southern Italy. The CSU 3-D nonlinear numerical model is utilised to simulate the dynamics and the thermodynamics of the atmospheric fields over Calabria. Results show the importance of orography in determining the pattern of the flow and the local climate in a region as complex as Calabria. Analysis of the results shows that the energetics due to the sea-land interactions are more efficient when the peninsula is flat. The importance of the energy due to the sea-land decreases as the mountain height of the peninsula increases. The energy stored over the mountain gains in importance, untill it is released by the readjustment of the warm mountain air as it prevails over the energy released by the inland penetration of the sea breeze front. For instance, our results show that over a peninsula 100 km wide the energy over the mountain and the energy in the sea-land contrast are of the same order when the height of the mountain is about 700 m, for a 1500 m convective boundary layer (CBL depth. Over the Calabrian peninsula, the energy released by the hot air in the CBL of the mountain prevails over the energy released by the inland penetration of the sea air. Calabria is about 1500 m high and about 50 km wide, and the CBL is of the order of 1500 m. The energy over the mountain is about four time larger than the energy contained in the sea-land contrast. Furthermore, the energetics increase with the patch width of the peninsula, and when its half width is much less than the Rossby radius, the MAPE of the sea breeze is negligible. When its half width is much larger than the Rossby radius, the breezes from the two

Tectonic-magmatic interplay during the early stages of oceanic rifting: temporal constraints from cosmogenic 3He dating in the Dabbahu rift segment, Afar

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Williams, A.; Pik, R.; Burnard, P.; Medynski, S.; Yirgu, G.

2009-12-01

. Available cosmogenic 3He dating of lava flow surfaces constrains the first phase of activity at rift axis to between 51 and 45 ka, coeval with basaltic activity at Baddi Volcano. Cosmogenic 3He dating of two major fault scarps in the Gabbole Valley yields ages of about 30-31 ka and 16-20 ka. Given the depths along the fault scarps at which samples were collected, these data constrain the timing of fault initiation in the region to c. 38 ka, shortly after the cessation of the first major phase of fissural basaltic activity on the rift-floor. The most recent basalts have eruption ages younger than 2000 yrs. All these dated basalts lie on the same differentiation trend as the Baddi basalts and Dabbahu volcanics, as defined by Barberi et al. (1974), using SiO2 vs. MgO and there is a clear relationship between degree of magma evolution and eruption age. The most recent basalts in the axial region also lie on this trend, but with a primitive composition similar to that of the Baddi basalts, strongly suggesting that the renewed seismicity in the segment is associated with a renewed magmatic cycle.

The rifted margin of Saudi Arabia

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McClain, J. S.; Orcutt, J. A.

The structure of rifted continental margins has always been of great scientific interest, and now, with dwindling economic oil deposits, these complex geological features assume practical importance as well. The ocean-continent transition is, by definition, laterally heterogeneous and likely to be extremely complicated. The southernmost shotpoints (4, 5, and 6) in the U.S. Geological Survey seismic refraction profile in the Kingdom of Saudi Arabia lie within a transition region and thus provide a testing ground for methods that treat wave propagation in laterally heterogeneous media. This portion of the profile runs from the Farasan Islands in the Red Sea across the coast line and the Hijaz-Asir escarpment into the Hijaz-Asir tectonic province. Because the southernmost shotpoint is within the margin of the Saudi sub-continent, the full transition region is not sampled. Furthermore, such an experiment is precluded by the narrowness of the purely oceanic portion of the Red Sea.

Understanding the groundwater dynamics in the Southern Rift Valley Lakes Basin (Ethiopia). Multivariate statistical analysis method, oxygen (δ 18O) and deuterium (δ 2H)

International Nuclear Information System (INIS)

Girum Admasu Nadew; Zebene Lakew Tefera

2013-01-01

Multivariate statistical analysis is very important to classify waters of different hydrochemical groups. Statistical techniques, such as cluster analysis, can provide a powerful tool for analyzing water chemistry data. This method is used to test water quality data and determine if samples can be grouped into distinct populations that may be significant in the geologic context, as well as from a statistical point of view. Multivariate statistical analysis method is applied to the geochemical data in combination with δ 18 O and δ 2 H isotopes with the objective to understand the dynamics of groundwater using hierarchical clustering and isotope analyses. The geochemical and isotope data of the central and southern rift valley lakes have been collected and analyzed from different works. Isotope analysis shows that most springs and boreholes are recharged by July and August rainfalls. The different hydrochemical groups that resulted from the multivariate analysis are described and correlated with the geology of the area and whether it has any interaction with a system or not. (author)

Using Detrital Zircon Geochronology to Constrain Paleogene Provenance and Its Relationship to Rifting in the Zhu 1 Depression, Pearl River Mouth Basin, South China Sea

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Wang, Wei; Ye, Jiaren; Bidgoli, Tandis; Yang, Xianghua; Shi, Hesheng; Shu, Yu

2017-11-01

Paleogene syn-rift successions in the South China Sea are poorly understood and systematic provenance analysis, which could provide clues to their history, is lacking. Here we report 409 new concordant U-Pb ages from detrital zircons separated from the Paleogene Wenchang, Enping, and Zhuhai formations in the Zhu 1 depression, Pearl River Mouth Basin. The new data, combined with the published age data from the region, document changes in the provenance of syn-rift successions. Detrital zircons from the Eocene Wenchang Formation are unimodal, with Jurassic-Cretaceous (180-80 Ma) ages making up >80% of grains. The ages are consistent with the geochronology of intrabasinal highs, dominated by igneous rocks emplaced during the Yanshanian orogeny, and suggest local provenance. By contrast, detrital zircons from the upper Eocene to lower Oligocene Enping Formation form three well-recognized age-clusters, with peaks at 150, 254, and 438 Ma that match documented tectonomagmatism in South China Block (SCB). Combined with increasing numbers of Precambrian zircons, the data suggest increasing influence of regional provenance of the SCB. Similar age peaks are also recognized from the limited number of zircons analyzed from the upper Oligocene Zhuhai Formation and comparability with modern shelf and river sediment indicates the unit was mainly sourced from the SCB and likely transported by a paleo-Pearl River. We infer that the change in provenance, from local uplifts within the Zhu 1 to the SCB, is related to distinct phases of PRMB rift development; however, later changes are best explained by SCB drainage evolution.

Venusian channels and valleys - Distribution and volcanological implications

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Komatsu, Goro; Baker, Victor R.; Gulick, Virginia C.; Parker, Timothy J.

1993-01-01

An updated map is presented which shows the distribution of more than 200 channels and valleys on Venus. A large number of channels are concentrated in equatorial regions characterized by highlands, rift and fracture zones, an associated volcanic features. Many channels associated with flow deposits are similar to typical terrestrial lava drainage channels. They are associated with a wide range of volcanic edifices. More than half of the sinuous rilles are associated with coronae, coronalike features, or arachnoids. Corona volcanism driven by mantle plume events may explain this association. Many valley network are observed in highlands and in association with coronae, coronalike features, or arachnoids. This indicates that highlands and coronae provided fractures and flow-viscosity lavas, both of which seem to be required for network formation by lava sapping processes. Canali-type channels have a unique distribution limited to some plains regions.

Hydro-meteorological trends in the Gidabo catchment of the Rift Valley Lakes Basin of Ethiopia

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Belihu, Mamuye; Abate, Brook; Tekleab, Sirak; Bewket, Woldeamlak

2018-04-01

The global and regional variability and changes of climate and stream flows are likely to have significant influence on water resource availability. The magnitude and impacts of climate variability and change differs spatially and temporally. This study examines the long term hydroclimatic changes, analyses of the hydro-climate variability and detect whether there exist significant trend or not in the Gidabo catchment, rift valley lakes basin of Ethiopia. Precipitation, temperature and stream flow time series data were used in monthly, seasonal and annual time scales. The precipitation and temperature data span is between 1982 and 2014 and that of stream flow is between 1976 and 2006. To detect trends the analysis were done by using Mann Kendal (MK), Sen's graphical method and to detect change point using the Pettit test. The comparison of trend analysis between MK trend test and Sen graphical method results depict mostly similar pattern. The annual rainfall trends exhibited a significant decrease by about 12 mm per year in the upstream, which is largely driven by the significant decrease in the peak season rainfall. The Pettit test revealed that the years 1997 and 2007 were the change points. It is noted that the rise of temperature over a catchment might have decreased the availability of soil moisture which resulted in less runoff. The temperature analyses also revealed that the catchment was getting warmer; particularly in the upstream. The minimum temperature trend showed a significant increase about 0.08°c per annum. There is generally a decreasing trend in stream flow. The monthly stream flow also exhibited a decreasing trend in February, March and September. The decline in annual and seasonal rainfall and the increase in temperature lead to more evaporation and directly affecting the stream flow negatively. This trend compounded with the growth of population and increasing demand for irrigation water exacerbates the competing demand for water resources. It

Orogenic inheritance and continental breakup: Wilson Cycle-control on rift and passive margin evolution

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Schiffer, C.; Petersen, K. D.

2016-12-01

observed seismically or exposed at the sea floor of passive margins, was formed prior to rifting in addition to syn-rift, fault-driven hydrothermal processes. Whether lower crustal and serpentinite bodies are produced previously or during rifting is of relevance for the estimation of thinning-factors of the pre-existing crust.

Biochemical and biophysical characterization of cell-free synthesized Rift Valley fever virus nucleoprotein capsids enables in vitro screening to identify novel antivirals.

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Broce, Sean; Hensley, Lisa; Sato, Tomoharu; Lehrer-Graiwer, Joshua; Essrich, Christian; Edwards, Katie J; Pajda, Jacqueline; Davis, Christopher J; Bhadresh, Rami; Hurt, Clarence R; Freeman, Beverly; Lingappa, Vishwanath R; Kelleher, Colm A; Karpuj, Marcela V

2016-05-14

Viral capsid assembly involves the oligomerization of the capsid nucleoprotein (NP), which is an essential step in viral replication and may represent a potential antiviral target. An in vitro transcription-translation reaction using a wheat germ (WG) extract in combination with a sandwich ELISA assay has recently been used to identify small molecules with antiviral activity against the rabies virus. Here, we examined the application of this system to viruses with capsids with a different structure, such as the Rift Valley fever virus (RVFV), the etiological agent of a severe emerging infectious disease. The biochemical and immunological characterization of the in vitro-generated RVFV NP assembly products enabled the distinction between intermediately and highly ordered capsid structures. This distinction was used to establish a screening method for the identification of potential antiviral drugs for RVFV countermeasures. These results indicated that this unique analytical system, which combines nucleoprotein oligomerization with the specific immune recognition of a highly ordered capsid structure, can be extended to various viral families and used both to study the early stages of NP assembly and to assist in the identification of potential antiviral drugs in a cost-efficient manner. Reviewed by Jeffry Skolnick and Noah Isakov. For the full reviews please go to the Reviewers' comments section.

Trace element mobility and transfer to vegetation within the Ethiopian Rift Valley lake areas.

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Kassaye, Yetneberk A; Skipperud, Lindis; Meland, Sondre; Dadebo, Elias; Einset, John; Salbu, Brit

2012-10-26

To evaluate critical trace element loads in native vegetation and calculate soil-to-plant transfer factors (TFs), 11 trace elements (Cr, Co, Ni, Cu, Zn, As, Se, Mo, Cd, Pb and Mn) have been determined in leaves of 9 taxonomically verified naturally growing terrestrial plant species as well as in soil samples collected around 3 Ethiopian Rift Valley lakes (Koka, Ziway and Awassa). The Cr concentration in leaves of all the plant species was higher than the "normal" range, with the highest level (8.4 mg per kg dw) being observed in Acacia tortilis from the Lake Koka area. Caper species (Capparis fascicularis) and Ethiopian dogstooth grass (Cynodon aethiopicus) from Koka also contained exceptionally high levels of Cd (1 mg per kg dw) and Mo (32.8 mg per kg dw), respectively. Pb, As and Cu concentrations were low in the plant leaves from all sites. The low Cu level in important fodder plant species (Cynodon aethiopicus, Acacia tortilis and Opuntia ficus-indicus) implies potential deficiency in grazing and browsing animals. Compared to the Canadian environmental quality guideline and maximum allowable concentration in agricultural soils, the total soil trace element concentrations at the studied sites are safe for agricultural crop production. Enrichment factor was high for Zn in soils around Lakes Ziway and Awassa, resulting in moderate to high transfer of Zn to the studied plants. A six step sequential extraction procedure on the soils revealed a relatively high mobility of Cd, Se and Mn. Strong association of most trace elements with the redox sensitive fraction and mineral lattice was also confirmed by partial redundancy analysis. TF (mg per kg dw plants/mg per kg dw soil) values based on the total (TF(total)) and mobile fractions (TF(mobile)) of soil trace element concentrations varied widely among elements and plant species, with the averaged TF(total) and TF(mobile) values ranging from 0.01-2 and 1-60, respectively. Considering the mobile fraction in soils should

3D Coupled Thermal-Hydraulic Model of the Lower Yarmouk Gorge, Jordan Rift Valley

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Walther, M.; Magri, F.; Inbar, N.; Möller, P.; Raggad, M.; Rödiger, T.; Rosenthal, E.; Shentsis, I.; Siebert, C.; Volpi, G.

2017-12-01

It is supposed that the Lower Yarmouk Gorge (LYG), in the Jordan Rift Valley acts as the mixing zone of two crossing flow pathways: N-S from the Hermon Mountains and from the Ajlun Dome, and E-W from Jebel al Arab Mountain in Syria (also known as Huran Plateau or Yarmouk drainage basin). As a result, several springs can be found within the gorge. These are characterized by widespread temperatures (20 - 60 °C) which indicate that, beside the complex regional flow, also ascending thermal waters control the hydrologic behavior of the LYG. Previous simulations based on a conceptual simplified 3D model (Magri et al., 2016) showed that crossing flow paths result from the coexistence of convection, that can develop for example along NE-SW oriented faults within the gorge or in permeable aquifers below Maastrichtian aquiclude, and additional flow fields that are induced by the N-S topographic gradients. Here we present the first 3D hydrogeological model of the entire LYG that includes structural features based on actual logs and interpreted seismic lines from both Israeli and Jordanian territories. The model distinguishes seven units from upper Eocene to the Lower Triassic, accounting for major aquifers, aquicludes and deep-cutting faults. Recharges are implemented based on the numerical representation developed by Shentsis (1990) that considers relationships between mean annual rain and topographic elevation. The model reveals that topography-driven N-S and E-W flows strongly control the location of discharge areas while the anomalous spring temperature is not necessarily linked to the presence of fault convection. Local permeability anisotropy due to aquifers folding or facies changes are features sufficient for the rising of hot fluids. Shentsis, I., 1990. Mathematical models for long-term prediction of mountainous river runoff: methods, information and results, Hydrological Sciences Journal, 35:5, 487-500 Magri, F., Möller, S., Inbar, N., Möller, P., Raggad, M., R�

Transmission of Rift Valley fever virus from European-breed lambs to Culex pipiens mosquitoes.

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Rianka P M Vloet

2017-12-01

Full Text Available Rift Valley fever virus (RVFV is a mosquito-borne bunyavirus of the genus Phlebovirus that is highly pathogenic to ruminants and humans. The disease is currently confined to Africa and the Arabian Peninsula, but globalization and climate change may facilitate introductions of the virus into currently unaffected areas via infected animals or mosquitoes. The consequences of such an introduction will depend on environmental factors, the availability of susceptible ruminants and the capacity of local mosquitoes to transmit the virus. We have previously demonstrated that lambs native to the Netherlands are highly susceptible to RVFV and we here report the vector competence of Culex (Cx. pipiens, the most abundant and widespread mosquito species in the country. Vector competence was first determined after artificial blood feeding of laboratory-reared mosquitoes using the attenuated Clone 13 strain. Subsequently, experiments with wild-type RVFV and mosquitoes hatched from field-collected eggs were performed. Finally, the transmission of RVFV from viremic lambs to mosquitoes was studied.Artificial feeding experiments using Clone 13 demonstrated that indigenous, laboratory-reared Cx. pipiens mosquitoes are susceptible to RVFV and that the virus can be transmitted via their saliva. Experiments with wild-type RVFV and mosquitoes hatched from field-collected eggs confirmed the vector competence of Cx. pipiens mosquitoes from the Netherlands. To subsequently investigate transmission of the virus under more natural conditions, mosquitoes were allowed to feed on RVFV-infected lambs during the viremic period. We found that RVFV is efficiently transmitted from lambs to mosquitoes, although transmission was restricted to peak viremia. Interestingly, in the mosquito-exposed skin samples, replication of RVFV was detected in previously unrecognized target cells.We here report the vector competence of Cx. pipiens mosquitoes from the Netherlands for RVFV. Both

Analysis of the pre-rift/rifte transition interval (Serraria and Barra de Itiuba formations) from the Sergipe-Alagoas basin; Analise da secao de transicao pre-rifte/rifte (formacoes Serraria e Barra de Itiuba) da Bacia Sergipe-Alagoas

Energy Technology Data Exchange (ETDEWEB)

Barreiro, C.B.; Mizusaki, A.M.P. [Rio Grande do Sul Univ., Porto Alegre, RS (Brazil)]. E-mail: camilita@terra.com.br; ana.misuzaki@ufrgs.br; Garcia, A.J.V. [Universidade do Vale do Rio dos Sinos (UNISINOS), Sao Leopoldo, RS (Brazil)]. E-mail: garcia@euler.unisinos.br

2003-07-01

The pre-rift/rift transition is represented by the Serraria and Barra de Itiuba formations. This interval was analyzed through qualitative and quantitative descriptions of cores, electric log analysis and studies of outcropping sections. The integration of surface and subsurface data allowed the stratigraphic characterization of sandstone bodies in the pre-rift/rift. These sandstones bodies were deposited by fluvial braided, lacustrine and deltaic systems (delta plain, delta front and pro delta). The sedimentary deposits characterized in the Serraria Formation are of channel, flooding of the fluvial system and eolic. The upper interval of this formation is characterized by to coarse medium-grained sandstones identified as the Caioba Sandstone. The Barra de Itiuba Formation contains lake, pro delta, frontal bar, distributary mouth, crevasse and distributary channel deposits. The sandstone units were specifically characterized in terms of their potential reservoir quality, and they were characterized the reservoirs R1 (good to medium quality) and Caioba (good quality) from the pre-rift phase, and reservoirs R2 (medium quality) and R3 (medium to good quality) from the rift phase. The reservoirs from pre-rift phase phase show the better reservoirs quality potential of the pre-rift/rift transition in the Sergipe-Alagoas Basin. (author)

Early to Middle Holocene sea level fluctuation, coastal progradation and the Neolithic occupation in the Yaojiang Valley of southern Hangzhou Bay, Eastern China

Science.gov (United States)

Liu, Yan; Sun, Qianli; Fan, Daidu; Dai, Bin; Ma, Fuwei; Xu, Lichen; Chen, Jing; Chen, Zhongyuan

2018-06-01

The Yaojiang Valley (YJV) of southern Hangzhou Bay was the birthplace of the well-known Hemudu Culture (HC), one of the representatives of Neolithic civilization in eastern China. To explore the magnitude of natural environmental effects on the HC trajectory, the palaeo-embayment setting of the YJV was studied in detail for the first time in terms of 3D Holocene strata supported by a series of new radiocarbon-dated cores. The results indicated that the local relative sea level rose rapidly during the Early Holocene in the YJV, reached its maximum flooding surface ca. 7900 cal yr BP, and then remained stable ca. 7900-7600 cal yr BP. Thereupon, an estuary stretching inland was first formed by marine transgression, and then, it was transformed to an alluvial-coastal plain by regressive progradation. The alluvial plain was initiated in the foothills and then spread towards the valley centre after sea level stabilization ca. 7600 cal yr BP. Accompanying these natural environmental changes, the earliest arrivals of foragers in the valley occurred no later than ca. 7000 cal yr BP. They engaged in rice farming and fostered the HC for approximately two millennia from ca. 7000-5000 cal yr BP as more lands developed from coastal progradation. The rise and development of the HC are closely associated with the sea level-induced landscape changes in the YJV in the Early-Middle Holocene, but the enigmatic exodus of the HC people after ca. 5000 cal yr BP is still contentious and possibly linked with the rapid waterlogging and deterioration of this setting in such a low-lying coastal plain as well as with associated social reasons.

Synoptic conditions of fine-particle transport to the last interglacial Red Sea-Dead Sea from Nd-Sr compositions of sediment cores

Science.gov (United States)

Palchan, Daniel; Stein, Mordechai; Goldstein, Steven L.; Almogi-Labin, Ahuva; Tirosh, Ofir; Erel, Yigal

2018-01-01

The sediments deposited at the depocenter of the Dead Sea comprise high-resolution archive of hydrological changes in the lake's watershed and record the desert dust transport to the region. This paper reconstructs the dust transport to the region during the termination of glacial Marine Isotope Stage 6 (MIS 6; ∼135-129 ka) and the last interglacial peak period (MIS5e, ∼129-116 ka). We use chemical and Nd and Sr isotope compositions of fine detritus material recovered from sediment core drilled at the deepest floor of the Dead Sea. The data is integrated with data achieved from cores drilled at the floor of the Red Sea, thus, forming a Red Sea-Dead Sea transect extending from the desert belt to the Mediterranean climate zone. The Dead Sea accumulated flood sediments derived from three regional surface cover types: settled desert dust, mountain loess-soils and loess-soils filling valleys in the Dead Sea watershed termed here "Valley Loess". The Valley Loess shows a distinct 87Sr/86Sr ratio of 0.7081 ± 1, inherited from dissolved detrital calcites that originate from dried waterbodies in the Sahara and are transported with the dust to the entire transect. Our hydro-climate and synoptic conditions reconstruction illustrates the following history: During glacial period MIS6, Mediterranean cyclones governed the transport of Saharan dust and rains to the Dead Sea watershed, driving the development of both mountain soils and Valley Loess. Then, at Heinrich event 11, dry western winds blew Saharan dust over the entire Red Sea - Dead Sea transect marking latitudinal expansion of the desert belt. Later, when global sea-level rose, the Dead Sea watershed went through extreme aridity, the lake retreated, depositing salt and accumulating fine detritus of the Valley Loess. During peak interglacial MIS 5e, enhanced flooding activity flushed the mountain soils and fine detritus from all around the Dead Sea and Red Sea, marking a significant "contraction" of the desert belt

Sea-floor drainage features of Cascadia Basin and the adjacent continental slope, northeast Pacific Ocean

Science.gov (United States)

Hampton, M.A.; Karl, Herman A.; Kenyon, Neil H.

1989-01-01

Sea-floor drainage features of Cascadia Basin and the adjacent continental slope include canyons, primary fan valleys, deep-sea valleys, and remnant valley segments. Long-range sidescan sonographs and associated seismic-reflection profiles indicate that the canyons may originate along a mid-slope escarpment and grow upslope by mass wasting and downslope by valley erosion or aggradation. Most canyons are partly filled with sediment, and Quillayute Canyon is almost completely filled. Under normal growth conditions, the larger canyons connect with primary fan valleys or deep-sea valleys in Cascadia Basin, but development of accretionary ridges blocks or re-routes most canyons, forcing abandonment of the associated valleys in the basin. Astoria Fan has a primary fan valley that connects with Astoria Canyon at the fan apex. The fan valley is bordered by parallel levees on the upper fan but becomes obscure on the lower fan, where a few valley segments appear on the sonographs. Apparently, Nitinat Fan does not presently have a primary fan valley; none of the numerous valleys on the fan connect with a canyon. The Willapa-Cascadia-Vancouver-Juan de Fuca deep-sea valley system bypasses the submarine fans and includes deeply incised valleys to broad shallow swales, as well as within-valley terraces and hanging-valley confluences. ?? 1989.

Validation of an ELISA for the concurrent detection of total antibodies (IgM and IgG to Rift Valley fever virus

Directory of Open Access Journals (Sweden)

Charlotte E. Ellis

2014-05-01

Full Text Available Rift Valley fever virus (RVFV infects humans and livestock, causing haemorrhaging andabortions in animals. Three major RVF epizootics have occurred in South Africa since the1950s and the outbreak in 2010 had a mortality rate of 10.7% in humans. Accurate and earlydetection is therefore essential for management of this zoonotic disease. Enzyme-linkedimmunosorbent assays (ELISAs have been developed for the detection of either IgM or IgGantibodies to RVFV in animal sera. In this study, data are presented on the validation of adouble-antigen ELISA for the simultaneous detection of both classes of antibodies to RVFV ina single test. ELISA plates were coated with a recombinant nucleoprotein. The nucleoprotein,conjugated to horseradish peroxidase, was used as the detecting reagent. A total of 534 serafrom sheep and cattle were used in the validation. The sheep sera were collected during a RVFpathogenesis study at the Agricultural Research Council (ARC – Onderstepoort VeterinaryInstitute and the cattle sera were collected during an outbreak of RVF in 2008 at the ARC –Animal Production Institute in Irene, Pretoria. The ELISA had a diagnostic sensitivity of 98.4%and a specificity of 100% when compared to a commercial cELISA. This convenient and fastassay is suitable for use in serological surveys or monitoring immune responses in vaccinatedanimals.

Farmers' perceptions of land degradation and their investments in land management: a case study in the Central Rift Valley of Ethiopia.

Science.gov (United States)

Adimassu, Zenebe; Kessler, Aad; Yirga, Chilot; Stroosnijder, Leo

2013-05-01

To combat land degradation in the Central Rift Valley (CRV) of Ethiopia, farmers are of crucial importance. If farmers perceive land degradation as a problem, the chance that they invest in land management measures will be enhanced. This study presents farmers' perceptions of land degradation and their investments in land management, and to what extent the latter are influenced by these perceptions. Water erosion and fertility depletion are taken as main indicators of land degradation, and the results show that farmers perceive an increase in both indicators over the last decade. They are aware of it and consider it as a problem. Nevertheless, farmers' investments to control water erosion and soil fertility depletion are very limited in the CRV. Results also show that farmers' awareness of both water erosion and soil fertility decline as a problem is not significantly associated with their investments in land management. Hence, even farmers who perceive land degradation on their fields and are concerned about its increase over the last decade do not significantly invest more in water erosion and soil fertility control measures than farmers who do not perceive these phenomena. Further research is needed to assess which other factors might influence farmers' investments in land management, especially factors related to socioeconomic characteristics of farm households and plot characteristics which were not addressed by this study.

Spatial Heterogeneity of Habitat Suitability for Rift Valley Fever Occurrence in Tanzania: An Ecological Niche Modelling Approach

Science.gov (United States)

Sindato, Calvin; Stevens, Kim B.; Karimuribo, Esron D.; Mboera, Leonard E. G.; Paweska, Janusz T.; Pfeiffer, Dirk U.

2016-01-01

Background Despite the long history of Rift Valley fever (RVF) in Tanzania, extent of its suitable habitat in the country remains unclear. In this study we investigated potential effects of temperature, precipitation, elevation, soil type, livestock density, rainfall pattern, proximity to wild animals, protected areas and forest on the habitat suitability for RVF occurrence in Tanzania. Materials and Methods Presence-only records of 193 RVF outbreak locations from 1930 to 2007 together with potential predictor variables were used to model and map the suitable habitats for RVF occurrence using ecological niche modelling. Ground-truthing of the model outputs was conducted by comparing the levels of RVF virus specific antibodies in cattle, sheep and goats sampled from locations in Tanzania that presented different predicted habitat suitability values. Principal Findings Habitat suitability values for RVF occurrence were higher in the northern and central-eastern regions of Tanzania than the rest of the regions in the country. Soil type and precipitation of the wettest quarter contributed equally to habitat suitability (32.4% each), followed by livestock density (25.9%) and rainfall pattern (9.3%). Ground-truthing of model outputs revealed that the odds of an animal being seropositive for RVFV when sampled from areas predicted to be most suitable for RVF occurrence were twice the odds of an animal sampled from areas least suitable for RVF occurrence (95% CI: 1.43, 2.76, p < 0.001). Conclusion/Significance The regions in the northern and central-eastern Tanzania were more suitable for RVF occurrence than the rest of the regions in the country. The modelled suitable habitat is characterised by impermeable soils, moderate precipitation in the wettest quarter, high livestock density and a bimodal rainfall pattern. The findings of this study should provide guidance for the design of appropriate RVF surveillance, prevention and control strategies which target areas with

Development and characterization of a Rift Valley fever virus cell-cell fusion assay using alphavirus replicon vectors

International Nuclear Information System (INIS)

Filone, Claire Marie; Heise, Mark; Doms, Robert W.; Bertolotti-Ciarlet, Andrea

2006-01-01

Rift Valley fever virus (RVFV), a member of the Phlebovirus genus in the Bunyaviridae family, is transmitted by mosquitoes and infects both humans and domestic animals, particularly cattle and sheep. Since primary RVFV strains must be handled in BSL-3+ or BSL-4 facilities, a RVFV cell-cell fusion assay will facilitate the investigation of RVFV glycoprotein function under BSL-2 conditions. As for other members of the Bunyaviridae family, RVFV glycoproteins are targeted to the Golgi, where the virus buds, and are not efficiently delivered to the cell surface. However, overexpression of RVFV glycoproteins using an alphavirus replicon vector resulted in the expression of the glycoproteins on the surface of multiple cell types. Brief treatment of RVFV glycoprotein expressing cells with mildly acidic media (pH 6.2 and below) resulted in rapid and efficient syncytia formation, which we quantified by β-galactosidase α-complementation. Fusion was observed with several cell types, suggesting that the receptor(s) for RVFV is widely expressed or that this acid-dependent virus does not require a specific receptor to mediate cell-cell fusion. Fusion occurred over a broad temperature range, as expected for a virus with both mosquito and mammalian hosts. In contrast to cell fusion mediated by the VSV-G glycoprotein, RVFV glycoprotein-dependent cell fusion could be prevented by treating target cells with trypsin, indicating that one or more proteins (or protein-associated carbohydrate) on the host cell surface are needed to support membrane fusion. The cell-cell fusion assay reported here will make it possible to study the membrane fusion activity of RVFV glycoproteins in a high-throughput format and to screen small molecule inhibitors for the ability to block virus-specific membrane fusion

Identifying landscape features associated with Rift Valley fever virus transmission, Ferlo region, Senegal, using very high spatial resolution satellite imagery.

Science.gov (United States)

Soti, Valérie; Chevalier, Véronique; Maura, Jonathan; Bégué, Agnès; Lelong, Camille; Lancelot, Renaud; Thiongane, Yaya; Tran, Annelise

2013-03-01

Dynamics of most of vector-borne diseases are strongly linked to global and local environmental changes. Landscape changes are indicators of human activities or natural processes that are likely to modify the ecology of the diseases. Here, a landscape approach developed at a local scale is proposed for extracting mosquito favourable biotopes, and for testing ecological parameters when identifying risk areas of Rift Valley fever (RVF) transmission. The study was carried out around Barkedji village, Ferlo region, Senegal. In order to test whether pond characteristics may influence the density and the dispersal behaviour of RVF vectors, and thus the spatial variation in RVFV transmission, we used a very high spatial resolution remote sensing image (2.4 m resolution) provided by the Quickbird sensor to produce a detailed land-cover map of the study area. Based on knowledge of vector and disease ecology, seven landscape attributes were defined at the pond level and computed from the land-cover map. Then, the relationships between landscape attributes and RVF serologic incidence rates in small ruminants were analyzed through a beta-binomial regression. Finally, the best statistical model according to the Akaike Information Criterion corrected for small samples (AICC), was used to map areas at risk for RVF. Among the derived landscape variables, the vegetation density index (VDI) computed within a 500 m buffer around ponds was positively correlated with serologic incidence (premote sensing data for identifying environmental risk factors and mapping RVF risk areas at a local scale.

Simulation modelling of population dynamics of mosquito vectors for rift valley Fever virus in a disease epidemic setting.

Directory of Open Access Journals (Sweden)

Clement N Mweya

Full Text Available Rift Valley Fever (RVF is weather dependent arboviral infection of livestock and humans. Population dynamics of mosquito vectors is associated with disease epidemics. In our study, we use daily temperature and rainfall as model inputs to simulate dynamics of mosquito vectors population in relation to disease epidemics.Time-varying distributed delays (TVDD and multi-way functional response equations were implemented to simulate mosquito vectors and hosts developmental stages and to establish interactions between stages and phases of mosquito vectors in relation to vertebrate hosts for infection introduction in compartmental phases. An open-source modelling platforms, Universal Simulator and Qt integrated development environment were used to develop models in C++ programming language. Developed models include source codes for mosquito fecundity, host fecundity, water level, mosquito infection, host infection, interactions, and egg time. Extensible Markup Language (XML files were used as recipes to integrate source codes in Qt creator with Universal Simulator plug-in. We observed that Floodwater Aedines and Culicine population continued to fluctuate with temperature and water level over simulation period while controlled by availability of host for blood feeding. Infection in the system was introduced by floodwater Aedines. Culicines pick infection from infected host once to amplify disease epidemic. Simulated mosquito population show sudden unusual increase between December 1997 and January 1998 a similar period when RVF outbreak occurred in Ngorongoro district.Findings presented here provide new opportunities for weather-driven RVF epidemic simulation modelling. This is an ideal approach for understanding disease transmission dynamics towards epidemics prediction, prevention and control. This approach can be used as an alternative source for generation of calibrated RVF epidemics data in different settings.

Simulation modelling of population dynamics of mosquito vectors for rift valley Fever virus in a disease epidemic setting.

Science.gov (United States)

Mweya, Clement N; Holst, Niels; Mboera, Leonard E G; Kimera, Sharadhuli I

2014-01-01

Rift Valley Fever (RVF) is weather dependent arboviral infection of livestock and humans. Population dynamics of mosquito vectors is associated with disease epidemics. In our study, we use daily temperature and rainfall as model inputs to simulate dynamics of mosquito vectors population in relation to disease epidemics. Time-varying distributed delays (TVDD) and multi-way functional response equations were implemented to simulate mosquito vectors and hosts developmental stages and to establish interactions between stages and phases of mosquito vectors in relation to vertebrate hosts for infection introduction in compartmental phases. An open-source modelling platforms, Universal Simulator and Qt integrated development environment were used to develop models in C++ programming language. Developed models include source codes for mosquito fecundity, host fecundity, water level, mosquito infection, host infection, interactions, and egg time. Extensible Markup Language (XML) files were used as recipes to integrate source codes in Qt creator with Universal Simulator plug-in. We observed that Floodwater Aedines and Culicine population continued to fluctuate with temperature and water level over simulation period while controlled by availability of host for blood feeding. Infection in the system was introduced by floodwater Aedines. Culicines pick infection from infected host once to amplify disease epidemic. Simulated mosquito population show sudden unusual increase between December 1997 and January 1998 a similar period when RVF outbreak occurred in Ngorongoro district. Findings presented here provide new opportunities for weather-driven RVF epidemic simulation modelling. This is an ideal approach for understanding disease transmission dynamics towards epidemics prediction, prevention and control. This approach can be used as an alternative source for generation of calibrated RVF epidemics data in different settings.

Serological evidence of Rift Valley fever virus circulation in sheep and goats in Zambézia Province, Mozambique.

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José Fafetine

Full Text Available Rift Valley fever (RVF is endemic in most parts of Africa and has also been reported to occur in the Arabian Peninsula. It is responsible for significant morbidity and mortality, particularly in livestock, but also in humans. During the last two decades several outbreaks of RVF have been reported in countries in Southern Africa. In contrast to other countries, no clinical disease has been reported in Mozambique during this period. In a serological study conducted in 2007 in five districts of Zambézia Province, Mozambique, of a total of 654 small ruminants sampled (277 sheep and 377 goats, 35.8% of sheep sera and 21.2% of goat sera were positive for RVF virus (RVFV antibodies in a virus neutralization test (VN and in an IgG enzyme-linked immunosorbent assay (ELISA. In 2010, a cross-sectional survey was conducted in 313 sheep and 449 goats in two districts of the same province. This study revealed an overall seropositivity rate of 9.2% in sheep and 11.6% in goat and an increased likelihood of being seropositive in older animals (OR = 7.3; p<0.001 using an IgG ELISA. 29 out of 240 animals assessed for RVF specific IgM by ELISA were positive, suggesting recent exposure to RVFV. However, a longitudinal study carried out between September 2010 and April 2011 in a cohort of 125 of these animals (74 sheep and 51 goats failed to demonstrate seroconversion. The results of the study indicate that RVFV circulates sub-clinically in domestic small ruminants in Zambézia Province.

NSs protein of rift valley fever virus induces the specific degradation of the double-stranded RNA-dependent protein kinase.

Science.gov (United States)

Habjan, Matthias; Pichlmair, Andreas; Elliott, Richard M; Overby, Anna K; Glatter, Timo; Gstaiger, Matthias; Superti-Furga, Giulio; Unger, Hermann; Weber, Friedemann

2009-05-01

Rift Valley fever virus (RVFV) continues to cause large outbreaks of acute febrile and often fatal illness among humans and domesticated animals in Africa, Saudi Arabia, and Yemen. The high pathogenicity of this bunyavirus is mainly due to the viral protein NSs, which was shown to prevent transcriptional induction of the antivirally active type I interferons (alpha/beta interferon [IFN-alpha/beta]). Viruses lacking the NSs gene induce synthesis of IFNs and are therefore attenuated, whereas the noninducing wild-type RVFV strains can only be inhibited by pretreatment with IFN. We demonstrate here in vitro and in vivo that a substantial part of the antiviral activity of IFN against RVFV is due to a double-stranded RNA-dependent protein kinase (PKR). PKR-mediated virus inhibition, however, was much more pronounced for the strain Clone 13 with NSs deleted than for the NSs-expressing strain ZH548. In vivo, Clone 13 was nonpathogenic for wild-type (wt) mice but could regain pathogenicity if mice lacked the PKR gene. ZH548, in contrast, killed both wt and PKR knockout mice indiscriminately. ZH548 was largely resistant to the antiviral properties of PKR because RVFV NSs triggered the specific degradation of PKR via the proteasome. The NSs proteins of the related but less virulent sandfly fever Sicilian virus and La Crosse virus, in contrast, had no such anti-PKR activity despite being efficient suppressors of IFN induction. Our data suggest that RVFV NSs has gained an additional anti-IFN function that may explain the extraordinary pathogenicity of this virus.

Gravity study of the Central African Rift system: a model of continental disruption 2. The Darfur domal uplift and associated Cainozoic volcanism

Science.gov (United States)

Bermingham, P. M.; Fairhead, J. D.; Stuart, G. W.

1983-05-01

Gravity studies of the Darfur uplift, Western Sudan, show it to be associated with a circular negative Bouguer anomaly, 50 mGal in amplitude and 700 km across. A three-dimensional model interpretation of the Darfur anomaly, using constraints deduced from geophysical studies of similar but more evolved Kenya and Ethiopia domes, suggests either a low-density laccolithic body at mid-lithospheric depth (~ 60 km) or a thinned lithosphere with emplacement at high level of low-density asthenospheric material. The regional setting of the Darfur uplift is described in terms of it being an integral part of the Central African Rift System which is shown to be broadly equivalent to the early to middle Miocene stage in the development of the Afro-Arabian Rift System. Comparisons between these rift systems suggest that extensional tectonics and passive rifting, resulting in the subsiding sedimentary rift basins associated with the Ngaoundere, Abu Gabra, Red Sea and Gulf of Aden rifts, are more typical of the early stage development of passive continental margins than the active domal uplift and development of rifted features associated with the Darfur, Kenya and Ethiopia domes.

Stratigraphic architecture of back-filled incised-valley systems: Pennsylvanian-Permian lower Cutler beds, Utah, USA

Science.gov (United States)

Wakefield, Oliver J. W.; Mountney, Nigel P.

2013-12-01

The Pennsylvanian to Permian lower Cutler beds collectively form the lowermost stratigraphic unit of the Cutler Group in the Paradox Basin, southeast Utah. The lower Cutler beds represent a tripartite succession comprising lithofacies assemblages of aeolian, fluvial and shallow-marine origin, in near equal proportion. The succession results from a series of transgressive-regressive cycles, driven by repeated episodes of climatic variation and linked changes in relative sea-level. Relative sea-level changes created a number of incised-valleys, each forming through fluvial incision during lowered base-level. Aeolian dominance during periods of relative sea-level lowstand aids incised-valley identification as the erosive bounding surface juxtaposes incised-valley infill against stacked aeolian faces. Relative sea-level rises resulted in back-flooding of the incised-valleys and their infill via shallow-marine and estuarine processes. Back-flooded valleys generated marine embayments within which additional local accommodation was exploited. Back-filling is characterised by a distinctive suite of lithofacies arranged into a lowermost, basal fill of fluvial channel and floodplain architectural elements, passing upwards into barform elements with indicators of tidal influence, including inclined heterolithic strata and reactivation surfaces. The incised-valley fills are capped by laterally extensive and continuous marine limestone elements that record the drowning of the valleys and, ultimately, flooding and accumulation across surrounding interfluves (transgressive surface). Limestone elements are characterised by an open-marine fauna and represent the preserved expression of maximum transgression.

Modelling the Effects of Sea-level, Climate Change, Geology, and Tectonism on the Morphology of the Amazon River Valley and its Floodplain

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Aalto, R. E.; Cremon, E.; Dunne, T.

2017-12-01

How continental-scale rivers respond to climate, geology, and sea level change is not well represented in morphodynamic models. Large rivers respond to influences less apparent in the form and deposits of smaller streams, as the huge scales require long time periods for changes in form and behavior. Tectonic deformation and excavation of resistant deposits can affect low gradient continental-scale rivers, thereby changing flow pathways, channel slope and sinuosity, along-stream patterns of sediment transport capacity, channel patterns, floodplain construction, and valley topography. Nowhere are such scales of morphodynamic response grander than the Amazon River, as described in papers by L.A.K. Mertes. Field-based understanding has improved over the intervening decades, but mechanistic models are needed to simulate and synthesize key morphodynamic components relevant to the construction of large river valleys, with a focus on the Amazon. The Landscape-Linked Environmental Model (LLEM) utilizes novel massively parallel computer architectures to simulate multiple-direction flow, sediment transport, deposition, and incision for exceptionally large (30-80 million nodes per compute unit) lowland dispersal systems. LLEM represents key fluvial processes such as bed and bar deposition, lateral and vertical erosion/incision, levee and floodplain construction, floodplain hydrology, `badlands dissection' of weak sedimentary deposits during falling sea level, tectonic and glacial-isostatic deformation, and provides a 3D record of created stratigraphy and underlying bedrock. We used LLEM to simulate the development of the main valley of the Amazon over the last million years, exploring the propagation of incision waves and system dissection during glacial lowstands, followed by rapid valley filling and extreme lateral mobility of channels during interglacials. We present metrics, videos, and 3D fly-throughs characterizing how system development responds to key assumptions

Post-Pan-African tectonic evolution of South Malawi in relation to the Karroo and recent East African rift systems

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Castaing, C.

1991-05-01

Structural studies conducted in the Lengwe and Mwabvi Karroo basins and in the basement in South Malawi, using regional maps and published data extended to cover Southeast Africa, serve to propose a series of geodynamic reconstructions which reveal the persistence of an extensional tectonic regime, the minimum stress σ3 of which has varied through time. The period of Karroo rifting and the tholeiitic and alkaline magmatism which terminated it, were controlled by NW-SE extension, which resulted in the creation of roughly NE-SW troughs articulated by the Tanganyika-Malawi and Zambesi pre-transform systems. These were NW-SE sinistral-slip systems with directions of movement dipping slightly to the Southeast, which enabled the Mwanza fault to play an important role in the evolution of the Karroo basins of the Shire Valley. The Cretaceous was a transition period between the Karroo rifting and the formation of the Recent East African Rift System. Extension was NE-SW, with some evidence for a local compressional episode in the Lengwe basin. Beginning in the Cenozoic, the extension once more became NW-SE and controlled the evolution in transtension of the Recent East African Rift System. This history highlights the major role of transverse faults systems dominated by strike-slip motion in the evolution and perpetuation of the continental rift systems. These faults are of a greater geological persistence than the normal faults bounding the grabens, especially when they are located on major basement anisotropies.

Infill of tunnel valleys associated with landward‐flowing ice sheets

DEFF Research Database (Denmark)

Moreau, Julien; Huuse, Mads

2014-01-01

The southern termination of the Middle and Late Pleistocene Scandinavian ice sheets was repeatedly located in the southern North Sea (sNS) and adjacent, north-sloping land areas. Giant meltwater-excavated valleys (tunnel valleys) formed at the southern termination of the ice sheets and contain...

Kinematics of the entire East African Rift from GPS velocities

Science.gov (United States)

Floyd, M.; King, R. W.

2017-12-01

Through a collaborative effort of the GeoPRISMS East Africa Rift GPS Working Group, we have collected and collated all of the publicly available continuous and survey-mode data for the entire rift system between 1994 and 2017 and processed these data as part of a larger velocity solution for Africa, Arabia and western Eurasia. We present here our velocity solution encompassing the major bounding plates and intervening terranes along the East African Rift from the Red Sea to the Malawi Rift and adjacent regions for GPS sites with data spans of at least 2.4 years, and north and east velocity uncertainties less than 1.5 mm/yr. To obtain realistic uncertainties for the velocity estimates, we attempted at each stage of the analysis to account for the character of the noise: During phase processing, we used an elevation-dependent weighting based on the phase residuals for each station; we then examined each position time series, removing outliers and reweighting appropriately to account for the white noise component of the errors; and e accounted for temporal correlations by estimating an equivalent random-walk magnitude for each continuous site and applying the median value (0.5 mm/√yr) to all survey-mode sites. We rigorously estimate relative rotation rates of Nubia, by choosing subset of well-determined sites such that the effective weights of western, northeastern and southern Africa were roughly equivalent, and Somalia, for which the estimate is dominated by three sites (MALI, RCMN, SEY1) whose uncertainties are a factor of 2-3 smaller than those of the other sites. For both plates, the weighted root-mean-square of the velocity residuals is 0.5 mm/yr. Our unified velocity solution provides a geodetic framework and constraints on the continental-scale kinematics of surface motions as well as more local effects both within and outside of the rift structures. Specific focus areas with denser coverage than previous fields include the Danakil block, the Afar Rift, the

Young rift kinematics in the Tadjoura rift, western Gulf of Aden, Republic of Djibouti

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Daoud, Mohamed A.; Le Gall, Bernard; Maury, René C.; Rolet, JoëL.; Huchon, Philippe; Guillou, Hervé

2011-02-01

The Tadjoura rift forms the westernmost edge of the westerly propagating Sheba ridge, between Arabia and Somalia, as it enters into the Afar depression. From structural and remote sensing data sets, the Tadjoura rift is interpreted as an asymmetrical south facing half-graben, about 40 km wide, dominated by a large boundary fault zone to the north. It is partially filled up by the 1-3 Myr old Gulf Basalts which onlapped the older Somali Basalts along its shallower southern flexural margin. The major and trace element analysis of 78 young onshore lavas allows us to distinguish and map four distinct basaltic types, namely the Gulf, Somali, Goumarre, and Hayyabley Basalts. These results, together with radiometric age data, lead us to propose a revised volcano-stratigraphic sketch of the two exposed Tadjoura rift margins and to discriminate and date several distinct fault networks of this oblique rift. Morphological and statistical analyses of onshore extensional fault populations show marked changes in structural styles along-strike, in a direction parallel to the rift axis. These major fault disturbances are assigned to the arrest of axial fault tip propagation against preexisting discontinuities in the NS-oriented Arta transverse zone. According to our model, the sinistral jump of rifting into the Asal-Ghoubbet rift segment results from structural inheritance, in contrast with the en échelon or transform mechanism of propagation that prevailed along the entire length of the Gulf of Aden extensional system.

Resource assessment of the Imperial Valley. Final report

Energy Technology Data Exchange (ETDEWEB)

Biehler, S.; Lee, T.

1977-01-01

A resource assessment of the Imperial Valley has been made based on the use of the gravity anomalies as indicators of total excess mass. These data indicate a potential of producing electric power of 7 to 80 thousand megawatts for 30 years. Over half of the total potential is located in the Salton Sea Anomaly and approximately half of the potential of the Salton Sea field is water covered. An attempt has been made to assess not only the heat in storage in the fluid but also recoverable from the country rock by reinjection. Based on calculations, the natural recharge rate of heat in the Valley due to sea floor spreading is too small to give the resource an indefinite life-span since the economic rates of withdrawal appear to be at least an order of magnitude greater.

Potential impacts of damming the Juba Valley, western Somalia: Insights from geomorphology and alluvial history

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Williams, Martin

2014-05-01

In 1988 plans were well advanced to dam the Juba River in western Somalia. The aims of the Baardheere Dam Project were to generate hydroelectric power for the capital Mogadishu, and to provide water for irrigation in the Juba Valley. A reconnaissance survey on foot along 500 km of the river upstream of the proposed dam site at Baardheere and detailed geomorphic mapping from air photos provided a basis for reconstructing the late Quaternary alluvial history of the river and for assessing the potential impact of the proposed dam. The Juba River rises in the Ethiopian Highlands and is the only river in Somalia that flows to the sea. Its history reflects climatic events in Ethiopia, where the Rift Valley lakes were very low during the LGM (21±2 ka), and high for about 5, 000 years before and after then. Cave deposits in Somalia indicate wetter conditions at 13, 10, 7.5 and 1.5 ka. Alluvial terraces in the Juba Valley range in age from late Pleistocene to late Holocene but only attain a few metres above the present floodplain. This is because the dry tributary valleys contain limestone caves and fissures that divert any high flows from the parent river underground, a process not known when the project was first approved. The oldest preserved terrace was cemented by calcrete by 40 ka. Alluvial gravels were deposited at the outlet of dry tributary valleys during times of episodic high-energy flow between 26 ka and 28 ka. Finely laminated shelly sands accumulated at 10 ka to form the 5 m terrace. The 2 m terrace was laid down 3.2 ka ago as a slackwater deposit. The lack of high-level alluvial terraces raises doubts over plans to dam the river, since rapid leakage would occur from side valleys and the reservoir would not attain the height needed to generate hydroelectric power. It would submerge all existing arable land along the river. Finally, the presence in the late Holocene alluvium of the sub-fossil gastropods Bulinus truncatus and Biomphalaria pfeifferi, which are

GPS measurements of crustal deformation across the southern Arava Valley section of the Dead Sea Fault and implications to regional seismic hazard assessment

Science.gov (United States)

Hamiel, Yariv; Masson, Frederic; Piatibratova, Oksana; Mizrahi, Yaakov

2018-01-01

Detailed analysis of crustal deformation along the southern Arava Valley section of the Dead Sea Fault is presented. Using dense GPS measurements we obtain the velocities of new near- and far-field campaign stations across the fault. We find that this section is locked with a locking depth of 19.9 ± 7.7 km and a slip rate of 5.0 ± 0.8 mm/yr. The geodetically determined locking depth is found to be highly consistent with the thickness of the seismogenic zone in this region. Analysis of instrumental seismic record suggests that only 1% of the total seismic moment accumulated since the last large event occurred about 800 years ago, was released by small to moderate earthquakes. Historical and paleo-seismic catalogs of this region together with instrumental seismic data and calculations of Coulomb stress changes induced by the 1995 Mw 7.2 Nuweiba earthquake suggest that the southern Arava Valley section of the Dead Sea Fault is in the late stage of the current interseismic period.

Identifying Areas Suitable for the Occurrence of Rift Valley Fever in North Africa: Implications for Surveillance.

Science.gov (United States)

Arsevska, E; Hellal, J; Mejri, S; Hammami, S; Marianneau, P; Calavas, D; Hénaux, V

2016-12-01

Rift Valley fever (RVF) is a vector-borne zoonotic disease that has caused widespread outbreaks throughout Africa and the Arabian Peninsula, with serious consequences for livestock-based economies and public health. Although there have never been any reports of RVF in Morocco, Algeria, Tunisia and Libya, it is a priority disease in the Maghreb, due to the threat of introduction of the virus through transboundary livestock movements or infected mosquito vectors. However, the implementation of surveillance activities and early warning contingency plans requires better knowledge of the epidemiological situation. We conducted a multicriteria decision analysis, integrating host distribution with a combination of important ecological factors that drive mosquito abundance, to identify hotspots and suitable time periods for RVF enzootic circulation (i.e. stable transmission at a low to moderate level for an extended period of time) and an RVF epizootic event (i.e. a sudden occurrence of a large number of infected animals over a large geographic area) in the Maghreb. We also modelled vector species distribution using available information on vector presence and habitat preference. We found that the northern regions of the Maghreb were moderately suitable for RVF enzootics, but highly suitable for RVF epizootics. The vector species distribution model identified these regions as the most favourable mosquito habitats. Due to the low density of animal hosts and arid conditions, the desert region showed low RVF suitability, except in oases. However, the presence of competent vectors in putative unsuitable areas underlines the need for further assessments of mosquito habitat preference. This study produced monthly RVF suitability maps useful for animal health managers and veterinary services involved in designing risk-based surveillance programmes. The suitability maps can be further enhanced using existing country-specific sources of information and by incorporating knowledge

Contrasted continental rifting via plume-craton interaction: Applications to Central East African Rift

Directory of Open Access Journals (Sweden)

Alexander Koptev

2016-03-01

Full Text Available The East African Rift system (EARS provides a unique system with the juxtaposition of two contrasting yet simultaneously formed rift branches, the eastern, magma-rich, and the western, magma-poor, on either sides of the old thick Tanzanian craton embedded in a younger lithosphere. Data on the pre-rift, syn-rift and post-rift far-field volcanic and tectonic activity show that the EARS formed in the context of the interaction between a deep mantle plume and a horizontally and vertically heterogeneous lithosphere under far-field tectonic extension. We bring quantitative insights into this evolution by implementing high-resolution 3D thermo-mechanical numerical deformation models of a lithosphere of realistic rheology. The models focus on the central part of the EARS. We explore scenarios of plume-lithosphere interaction with plumes of various size and initial position rising beneath a tectonically pre-stretched lithosphere. We test the impact of the inherited rheological discontinuities (suture zones along the craton borders, of the rheological structure, of lithosphere plate thickness variations, and of physical and mechanical contrasts between the craton and the embedding lithosphere. Our experiments indicate that the ascending plume material is deflected by the cratonic keel and preferentially channeled along one of its sides, leading to the formation of a large rift zone along the eastern side of the craton, with significant magmatic activity and substantial melt amount derived from the mantle plume material. We show that the observed asymmetry of the central EARS, with coeval amagmatic (western and magmatic (eastern branches, can be explained by the splitting of warm material rising from a broad plume head whose initial position is slightly shifted to the eastern side of the craton. In that case, neither a mechanical weakness of the contact between the craton and the embedding lithosphere nor the presence of second plume are required to

3D hydrogeological model of the Lower Yarmouk Gorge, Jordan Rift Valley

Science.gov (United States)

Magri, Fabien; Inbar, Nimrod; Möller, Peter; Raggad, Marwan; Rödiger, Tino; Rosenthal, Eliahu; Shentsis, Izabela; Tzoufka, Kalliopi; Siebert, Christian

2017-04-01

The Lower Yarmouk Gorge (LYG) lies on the eastern margin of the lower Jordan Rift Valley (JRV), bounded to the south by the Ajlun and to the north by the Golan Heights. It allows the outflow of the Yarmouk drainage basin and flow into the Jordan River, a few kilometers south of Lake Tiberias. The main aquifer system of the LYG is built mostly of Cretaceous sandstones and carbonates confined by Maastrichtian aquiclude. Fissures allow hydraulic connections between the major water-bearing formations from Quaternary to Upper Cretaceous age. It is supposed that the gorge acts as the mixing zone of two crossing flow pathways: N-S from the Hermon Mountains and from the Ajlun Dome, and E-W from Jebel al Arab Mountain in Syria (also known as Huran Plateau or Yarmouk drainage basin). As a result, several springs can be found within the gorge. These are characterized by widespread temperatures (20 - 60 °C) which indicate that, beside the complex regional flow, also ascending thermal waters control the hydrologic behavior of the LYG. Previous simulations based on a conceptual simplified 3D model (Magri et al., 2016) showed that crossing flow paths result from the coexistence of convection, that can develop for example along NE-SW oriented faults within the gorge or in permeable aquifers below Maastrichtian aquiclude, and additional flow fields that are induced by the N-S topographic gradients. Here we present the first 3D hydrogeological model of the entire LYG that includes structural features based on actual logs and interpreted seismic lines from both Israeli and Jordanian territories. The model distinguishes seven units from upper Eocene to the Lower Triassic, accounting for major aquifers, aquicludes and deep-cutting faults. Recharges are implemented based on the numerical representation developed by Shentsis (1990) that considers relationships between mean annual rain and topographic elevation. The model reveals that topography-driven N-S and E-W flows strongly control

Crustal and mantle structure and anisotropy beneath the incipient segments of the East African Rift System: Preliminary results from the ongoing SAFARI

Science.gov (United States)

Yu, Y.; Reed, C. A.; Gao, S. S.; Liu, K. H.; Massinque, B.; Mdala, H. S.; moidaki, M.; Mutamina, D. M.; Atekwana, E. A.; Ingate, S. F.; Reusch, A.; Barstow, N.

2013-12-01

Despite the vast wealth of research conducted toward understanding processes associated with continental rifting, the extent of our knowledge is derived primarily from studies focused on mature rift systems, such as the well-developed portions of the East African Rift System (EARS) north of Lake Malawi. To explore the dynamics of early rift evolution, the SAFARI (Seismic Arrays for African Rift Initiation) team deployed 50 PASSCAL broadband seismic stations across the Malawi, Luangwa, and Okavango rifts of the EARS during the summer of 2012. The cumulative length of the profiles is about 2500 km and the planned recording duration is 2 years. Here we present the preliminary results of systematic analyses of data obtained from the first year of acquisition for all 50 stations. A total of 446 high-quality shear-wave splitting measurements using PKS, SKKS, and SKS phases from 84 teleseismic events were used to constrain fast polarization directions and splitting times throughout the region. The Malawi and Okavango rifts are characterized by mostly NE trending fast directions with a mean splitting time of about 1 s. The fast directions on the west side of the Luangwa Rift Zone are parallel to the rift valley, and those on the east side are more N-S oriented. Stacking of approximately 1900 radial receiver functions reveals significant spatial variations of both crustal thickness and the ratio of crustal P and S wave velocities, as well as the thickness of the mantle transition zone. Stations situated within the Malawi rift demonstrate a southward increase in observed crustal thickness, which is consistent with the hypothesis that the Malawi rift originated at the northern end of the rift system and propagated southward. Both the Okavango and Luangwa rifts are associated with thinned crust and increased Vp/Vs, although additional data is required at some stations to enhance the reliability of the observations. Teleseismic P-wave travel-time residuals show a delay of about

Immunogenicity of a recombinant Rift Valley fever MP-12-NSm deletion vaccine candidate in calves.

Science.gov (United States)

Morrill, John C; Laughlin, Richard C; Lokugamage, Nandadeva; Wu, Jing; Pugh, Roberta; Kanani, Pooja; Adams, L Garry; Makino, Shinji; Peters, C J

2013-10-09

The safety and immunogenicity of an authentic recombinant (ar) of the live, attenuated MP-12 Rift Valley fever (RVF) vaccine virus with a large deletion of the NSm gene in the pre-Gn region of the M RNA segment (arMP-12ΔNSm21/384) was tested in 4-6 month old Bos taurus calves. Phase I of this study evaluated the neutralizing antibody response, measured by 80% plaque reduction neutralization (PRNT80), and clinical response of calves to doses of 1 × 10(1) through 1 × 10(7) plaque forming units (PFU) administered subcutaneously (s.c.). Phase II evaluated the clinical and neutralizing antibody response of calves inoculated s.c. or intramuscularly (i.m.) with 1 × 10(3), 1 × 10(4) or 1 × 10(5)PFU of arMP-12ΔNSm21/384. No significant adverse clinical events were observed in the animals in these studies. Of all specimens tested, only one vaccine viral isolate was recovered and that virus retained the introduced deletion. In the Phase I study, there was no statistically significant difference in the PRNT80 response between the dosage groups though the difference in IgG response between the 1 × 10(1)PFU group and the 1 × 10(5)PFU group was statistically significant (pPFU dose group showing the least response. The Phase II study also showed no statistically significant difference in PRNT80 response between the dosage groups though the difference in RVFV-specific IgG values was significantly increased (pPFU versus those inoculated s.c. with 1 × 10(3) or 1 × 10(5)PFU. Although the study groups were small, these data suggest that 1 × 10(4) or 1 × 10(5)PFU of arMP-12ΔNSm21/384 administered i.m. to calves will consistently stimulate a presumably protective PRNT80 response for at least 91 days post inoculation. Further studies of arMP-12ΔNSm21/384 are warranted to explore its suitability as an efficacious livestock vaccine. Copyright © 2013 Elsevier Ltd. All rights reserved.

The evolution of magma during continental rifting: New constraints from the isotopic and trace element signatures of silicic magmas from Ethiopian volcanoes

Science.gov (United States)

Hutchison, William; Mather, Tamsin A.; Pyle, David M.; Boyce, Adrian J.; Gleeson, Matthew L. M.; Yirgu, Gezahegn; Blundy, Jon D.; Ferguson, David J.; Vye-Brown, Charlotte; Millar, Ian L.; Sims, Kenneth W. W.; Finch, Adrian A.

2018-05-01

Magma plays a vital role in the break-up of continental lithosphere. However, significant uncertainty remains about how magma-crust interactions and melt evolution vary during the development of a rift system. Ethiopia captures the transition from continental rifting to incipient sea-floor spreading and has witnessed the eruption of large volumes of silicic volcanic rocks across the region over ∼45 Ma. The petrogenesis of these silicic rocks sheds light on the role of magmatism in rift development, by providing information on crustal interactions, melt fluxes and magmatic differentiation. We report new trace element and Sr-Nd-O isotopic data for volcanic rocks, glasses and minerals along and across active segments of the Main Ethiopian (MER) and Afar Rifts. Most δ18 O data for mineral and glass separates from these active rift zones fall within the bounds of modelled fractional crystallization trajectories from basaltic parent magmas (i.e., 5.5-6.5‰) with scant evidence for assimilation of Pan-African Precambrian crustal material (δ18 O of 7-18‰). Radiogenic isotopes (εNd = 0.92- 6.52; 87Sr/86Sr = 0.7037-0.7072) and incompatible trace element ratios (Rb/Nb productivity or where crustal structure inhibits magma ascent). This has important implications for understanding the geotectonic settings that promote extreme melt evolution and, potentially, genesis of economically-valuable mineral deposits in ancient rift-settings. The limited isotopic evidence for assimilation of Pan-African crustal material in Ethiopia suggests that the pre-rift crust beneath the magmatic segments has been substantially modified by rift-related magmatism over the past ∼45 Ma; consistent with geophysical observations. We argue that considerable volumes of crystal cumulate are stored beneath silicic volcanic systems (>100 km3), and estimate that crystal cumulates fill at least 16-30% of the volume generated by crustal extension under the axial volcanoes of the MER and Manda Hararo

Influence of system controls on the Late Quaternary geomorphic evolution of a rapidly-infilled incised-valley system: The lower Manawatu valley, North Island New Zealand

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Clement, Alastair J. H.; Fuller, Ian C.

2018-02-01

The Manawatu incised-valley estuary was rapidly infilled between 12,000-4700 cal. yr BP. A combination of empirical measurements of sedimentation rates, a reconstruction of relative sea-level (RSL) change, and digital elevation models of key surfaces within the Holocene sedimentary fill of the valley were integrated to produce a numerical model to investigate the influence of the system controls of sea-level change, sediment flux, and accommodation space on the rapid infilling history of the palaeo-estuary. The numerical model indicates that sediment flux into the palaeo-estuary was greatest during the Holocene marine transgression between 12,000-8000 years BP. The average rate of sediment deposition in the estuary during this period was 1.0 M m3 yr- 1. This rapid rate of sedimentation was controlled by the rate of accommodation space creation, as regulated by the rate of sea-level rise and the antecedent configuration of the valley. By the time sea levels stabilised c. 7500 cal. yr BP, the palaeo-estuary had been substantively infilled. Limited accommodation space resulted in rapid infilling of the central basin, though sediment flux into the estuary between 7100 and 4500 cal. yr BP was at a lower rate of 234,000 m3 yr- 1. The limited accommodation space also influenced hydrodynamic conditions in the estuarine central basin, driving export of fine-grained sediment from the estuary. Once the accommodation space of the estuarine basin was infilled sediment bypassed the system, with a consequent reduction in the sedimentation rate in the valley. More accurate partitioning of the sources of sediment driving the infilling is necessary to quantify sediment bypassing. Post-depositional lowering of RSL index points from the valley is driven by neotectonics and sediment compaction.

Comparative Riftology: Insights into the Evolution of Passive Continental Margins and Continental Rifts from the Failed Midcontinent Rift (MCR)

Science.gov (United States)

Elling, R. P.; Stein, C. A.; Stein, S.; Kley, J.; Keller, G. R.; Wysession, M. E.

2017-12-01

Continental rifts evolve to seafloor spreading and are preserved in passive margins, or fail and remain as fossil features in continents. Rifts at different stages give insight into these evolutionary paths. Of particular interest is the evolution of volcanic passive margins, which are characterized by seaward dipping reflectors, volcanic rocks yielding magnetic anomalies landward of the oldest spreading anomalies, and are underlain by high-velocity lower crustal bodies. How and when these features form remains unclear. Insights are given by the Midcontinent Rift (MCR), which began to form during the 1.1 Ga rifting of Amazonia from Laurentia, but failed when seafloor spreading was established elsewhere. MCR volcanics are much thicker than other continental flood basalts, due to deposition in a narrow rift rather than a broad region, giving a rift's geometry but a LIP's magma volume. The MCR provides a snapshot of the deposition of a thick and highly magnetized volcanic section during rifting. Surface exposures and reflection seismic data near Lake Superior show a rift basin filled by inward-dipping flood basalt layers. Had the rift evolved to seafloor spreading, the basin would have split into two sets of volcanics with opposite-facing SDRs, each with a magnetic anomaly. Because the rift formed as a series of alternating half-grabens, structural asymmetries between conjugate margins would have naturally occurred had it gone to completion. Hence the MCR implies that many passive margin features form prior to seafloor spreading. Massive inversion of the MCR long after it failed has provided a much clearer picture of its structure compared to failed rifts with lesser degrees of inversion. Seismic imaging as well as gravity and magnetic modeling provide important insight into the effects of inversion on failed rifts. The MCR provides an end member for the evolution of actively extending rifts, characterized by upwelling mantle and negative gravity anomalies, to failed

Inter-epidemic abundance and distribution of potential mosquito vectors for Rift Valley fever virus in Ngorongoro district, Tanzania.

Science.gov (United States)

Mweya, Clement N; Kimera, Sharadhuli I; Mellau, Lesakit S B; Mboera, Leonard E G

2015-01-01

Rift Valley fever (RVF) is a mosquito-borne viral zoonosis that primarily affects ruminants but also has the capacity to infect humans. To determine the abundance and distribution of mosquito vectors in relation to their potential role in the virus transmission and maintenance in disease epidemic areas of Ngorongoro district in northern Tanzania. A cross-sectional entomological investigation was carried out before the suspected RVF outbreak in October 2012. Mosquitoes were sampled both outdoors and indoors using the Centre for Disease Control (CDC) light traps and Mosquito Magnets baited with attractants. Outdoor traps were placed in proximity with breeding sites and under canopy in banana plantations close to the sleeping places of animals. A total of 1,823 mosquitoes were collected, of which 87% (N=1,588) were Culex pipiens complex, 12% (N=226) Aedes aegypti, and 0.5% (N=9) Anopheles species. About two-thirds (67%; N=1,095) of C. pipiens complex and nearly 100% (N=225) of A. aegypti were trapped outdoors using Mosquito Magnets. All Anopheles species were trapped indoors using CDC light traps. There were variations in abundance of C. pipiens complex and A. aegypti among different ecological and vegetation habitats. Over three quarters (78%) of C. pipiens complex and most (85%) of the A. aegypti were trapped in banana and maize farms. Both C. pipiens complex and A. aegypti were more abundant in proximity with cattle and in semi-arid thorn bushes and lower Afro-montane. The highest number of mosquitoes was recorded in villages that were most affected during the RVF epidemic of 2007. Of the tested 150 pools of C. pipiens complex and 45 pools of A. aegypti, none was infected with RVF virus. These results provide insights into unique habitat characterisation relating to mosquito abundances and distribution in RVF epidemic-prone areas of Ngorongoro district in northern Tanzania.

Geometry of the neoproterozoic and paleozoic rift margin of western Laurentia: Implications for mineral deposit settings

Science.gov (United States)

Lund, K.

2008-01-01

The U.S. and Canadian Cordilleran miogeocline evolved during several phases of Cryogenian-Devonian intracontinental rifting that formed the western mangin of Laurentia. Recent field and dating studies across central Idaho and northern Nevada result in identification of two segments of the rift margin. Resulting interpretations of rift geometry in the northern U.S. Cordillera are compatible with interpretations of northwest- striking asymmetric extensional segments subdivided by northeast-striking transform and transfer segments. The new interpretation permits integration of miogeoclinal segments along the length of the western North American Cordillera. For the U.S. Cordillera, miogeoclinal segments include the St. Mary-Moyie transform, eastern Washington- eastern Idaho upper-plate margin, Snake River transfer, Nevada-Utah lower-plate margin, and Mina transfer. The rift is orthogonal to most older basement domains, but the location of the transform-transfer zones suggests control of them by basement domain boundaries. The zigzag geometry of reentrants and promontories along the rift is paralleled by salients and recesses in younger thrust belts and by segmentation of younger extensional domains. Likewise, transform transfer zones localized subsequent transcurrent structures and igneous activity. Sediment-hosted mineral deposits trace the same zigzag geometry along the margin. Sedimentary exhalative (sedex) Zn-Pb-Ag ??Au and barite mineral deposits formed in continental-slope rocks during the Late Devonian-Mississippian and to a lesser degree, during the Cambrian-Early Ordovician. Such deposits formed during episodes of renewed extension along miogeoclinal segments. Carbonate-hosted Mississippi Valley- type (MVT) Zn-Pb deposits formed in structurally reactivated continental shelf rocks during the Late Devonian-Mississippian and Mesozoic due to reactivation of preexisting structures. The distribution and abundance of sedex and MVT deposits are controlled by the

The Red Sea Basin Province: Sudr-Nubia(!) and Maqna(!) Petroleum Systems

Science.gov (United States)

Lindquist, Sandra J.

1999-01-01

The Sudr-Nubia(!) oil-prone total petroleum system dominates the densely explored Gulf of Suez part of the rifted Red Sea Basin Province. Upper Cretaceous to Eocene source rocks, primarily the Senonian Sudr Formation, are organic-rich, areally uniform marine carbonates that have generated known ultimate recoverable reserves exceeding 11 BBOE. The name Nubia is used for sandstone reservoirs with a wide range of poorly constrained, pre-rift geologic ages ranging from Early Paleozoic to Early Cretaceous. Syn- and post-rift Tertiary reservoirs, especially the Kareem Formation, also contain significant reserves. Partly overlapping Sudr-Nubia(!) is the areally larger and geochemically distinct, oil-and-gas-prone Maqna(!) total petroleum system within the southern Gulf of Suez basin and the sparsely explored remaining Red Sea basin. Known ultimate recoverable reserves are 50-100 MMBOE and more than 900 MMBOE, respectively, in those areas. Both the source and reservoir rocks in this petroleum system are Tertiary, dominantly Miocene, in age. Maqna(!) has the greater potential for future resource development.

Interim Report on SNP analysis and forensic microarray probe design for South American hemorrhagic fever viruses, tick-borne encephalitis virus, henipaviruses, Old World Arenaviruses, filoviruses, Crimean-Congo hemorrhagic fever viruses, Rift Valley fever

Energy Technology Data Exchange (ETDEWEB)

Jaing, C; Gardner, S

2012-06-05

The goal of this project is to develop forensic genotyping assays for select agent viruses, enhancing the current capabilities for the viral bioforensics and law enforcement community. We used a multipronged approach combining bioinformatics analysis, PCR-enriched samples, microarrays and TaqMan assays to develop high resolution and cost effective genotyping methods for strain level forensic discrimination of viruses. We have leveraged substantial experience and efficiency gained through year 1 on software development, SNP discovery, TaqMan signature design and phylogenetic signature mapping to scale up the development of forensics signatures in year 2. In this report, we have summarized the whole genome wide SNP analysis and microarray probe design for forensics characterization of South American hemorrhagic fever viruses, tick-borne encephalitis viruses and henipaviruses, Old World Arenaviruses, filoviruses, Crimean-Congo hemorrhagic fever virus, Rift Valley fever virus and Japanese encephalitis virus.

A New Structural Model for the Red Sea from Seismic Data

Science.gov (United States)

Mooney, W. D.; Yao, Z.; Zahran, H. M.; El-Hadidy, S. Y.

2017-12-01

We present a new structureal model for the Red Sea that shows opening on an east-dipping low-angle detachment fault. We measured phase velocities using Rayleigh-wave data recorded at recently-installed, dense broadband seismic stations in the Arabian shield and determined the shear-wave velocity structure. Our results clearly reveal a 300-km wide upper mantle seismic low-velocity zone (LVZ) beneath the western Arabian shield at a depth of 60 km and with a thickness of 130 km. The LVZ has a north-south trend and follows the late-Cenozoic volcanic areas. The lithosphere beneath the western Arabian shield is remarkably thin (60-90 km). The 130-km thick mantle LVZ does not appear beneath the western Red Sea and the spreading axis. Thus, the Red Sea at 20°- 26° N is an asymmetric rift, with thin lithosphere located east of the Red Sea axis, as predicted by the low-angle detachment model for rift development. Passive rifting at the Red Sea and extensional stresses in the shield are probably driven by slab pull from the Zagros subduction zone. The low shear-wave velocity (4.0-4.2 km/s) and the geometry of LVZ beneath the western shield indicate northward flow of hot asthenosphere from the Afar hot spot. The upwelling of basaltic melt in fractures or zones of localized lithospheric thinning has produced extensive late Cenozoic volcanism on the western edge of the shield, and the buoyant LVZ has caused pronounced topography uplift there. Thus, the evolution of the Red Sea and the Arabian shield is driven by subduction of the Arabian plate along its northeastern boundary, and the Red Sea opened on a east-dipping low-angle detachment fault.

Contrasted continental rifting via plume-craton interaction : Applications to Central East African Rift

NARCIS (Netherlands)

Koptev, Alexander; Burov, Evgueni; Calais, Eric; Leroy, Sylvie; Gerya, Taras; Guillou-Frottier, Laurent; Cloetingh, Sierd

The East African Rift system (EARS) provides a unique system with the juxtaposition of two contrasting yet simultaneously formed rift branches, the eastern, magma-rich, and the western, magma-poor, on either sides of the old thick Tanzanian craton embedded in a younger lithosphere. Data on the

Asynchronous behavior of the Antarctic Ice Sheet and local glaciers during and since Termination 1, Salmon Valley, Antarctica

Science.gov (United States)

Jackson, Margaret S.; Hall, Brenda L.; Denton, George H.

2018-01-01

The stability of the Antarctic Ice Sheet under future warming remains an open question with broad implications for sea-level prediction and adaptation. In particular, knowledge of whether the ice sheet has the capacity for rapid drawdown or collapse, or whether it can remain stable during periods of warming, is essential for predicting its future behavior. Here we use 55 radiocarbon dates, coupled with geomorphologic mapping, to reconstruct the timing of changes in ice extent and elevation during the last ice-age termination in Salmon Valley, adjacent to McMurdo Sound in the western Ross Sea Embayment. Results indicate that a grounded ice sheet in the Ross Sea Embayment achieved its maximum elevation and extent along the headlands of Salmon Valley at ∼18,000 yr BP, during a period of increasing temperatures and accumulation over the Antarctic continent. This ice remained at or near its maximum on the headlands near the valley mouth until after ∼14,000 yr BP. Removal of grounded Ross Sea ice from Salmon Valley was complete shortly after ∼7900 yr BP, indicating that the grounding line had retreated through southern McMurdo Sound by that time. We suggest the primary driver of Ross Sea ice removal from McMurdo Sound was marine-based, either through basal melting or calving due to sea-level rise. When combined with regional data, the Salmon Valley record suggests that this sector of the Antarctic Ice Sheet did not contribute in a significant way to deglacial meltwater pulses, such as meltwater pulse 1a. In contrast to the Ross Sea ice, our work also shows that local, independent alpine glaciers in Salmon Valley have advanced through the Holocene. Land-terminating glaciers such as these elsewhere in the region show a similar pattern, and may reflect the continued influence of increased accumulation following the termination of the last ice age.

Luminescence dating of paleolake deltas and glacial deposits in Garwood Valley, Antarctica: Implications for climate, Ross ice sheet dynamics, and paleolake duration

Science.gov (United States)

Levy, Joseph S.; Rittenour, Tammy M.; Fountain, Andrew G.; O'Connor, Jim E.

2017-01-01

The formation of perched deltas and other lacustrine deposits in the McMurdo Dry Valleys of Antarctica is widely considered to be evidence of valley-filling lakes dammed by the grounded Ross Sea ice sheet during the local Last Glacial Maximum, with lake drainage interpreted as a record of grounding line retreat. We used luminescence dating to determine the age of paleolake deltas and glacial tills in Garwood Valley, a coastal dry valley that opens to the Ross Sea. Luminescence ages are stratigraphically consistent with radiocarbon results from algal mats within the same delta deposits but suggest radiocarbon dates from lacustrine carbonates may overestimate deposit ages by thousands of years. Results suggest that late Holocene delta deposition into paleolake Howard in Garwood Valley persisted until ca. 3.5 ka. This is significantly younger than the date when grounded ice is thought to have retreated from the Ross Sea. Our evidence suggests that the local, stranded ice-cored till topography in Garwood Valley, rather than regional ice-sheet dynamics, may have controlled lake levels for some McMurdo Dry Valleys paleolakes. Age control from the supraglacial Ross Sea drift suggests grounding and up-valley advance of the Ross Sea ice sheet into Garwood valley during marine oxygen isotope stage (MIS) 4 (71–78 ka) and the local Last Glacial Maximum (9–10 ka). This work demonstrates the power of combining luminescence dating with existing radiocarbon data sets to improve understanding of the relationships among paleolake formation, glacial position, and stream discharge in response to climate change.

Preliminary sequence stratigraphy and tectonic evolution of the Tokar Delta, (Southern Sudanese Red Sea)

OpenAIRE

Yagoub, Abbas Musa

2007-01-01

The study area comprises about 2500sq.Kms. From the seismic data acquired by the Oil Companies (Chevron 1975-76 Total 1980 and IPC 1992), thirty two seismic lines were selected Fig (2). Also synthetic seismograms of Suakin-1, Bashayer-1 A and Bashayer-2A wells are used. The stratigraphy and sedimentation of the Sudanese Red Sea can be placed into four major tectonic phases, Pre-rifting stratigraphy, Syn-Rift Pre-Salt Stratigarphy, Salt Phase and Syn-Rift Post Salt Stratigraphy. Basic conce...

A Systematic Scoping Study of the Socio-Economic Impact of Rift Valley Fever: Research Gaps and Needs.

Science.gov (United States)

Peyre, M; Chevalier, V; Abdo-Salem, S; Velthuis, A; Antoine-Moussiaux, N; Thiry, E; Roger, F

2015-08-01

Rift Valley fever (RVF) is a severe mosquito-borne disease affecting humans and domestic ruminants. RVF virus has been reported in most African countries, as well as in the Arabic Peninsula. This paper reviews the different types of socio-economic impact induced by RVF disease and the attempts to evaluate them. Of the 52 papers selected for this review, 13 types of socio-economic impact were identified according to the sector impacted, the level and temporal scale of the impact. RVF has a dramatic impact on producers and livestock industries, affecting public and animal health, food security and the livelihood of the pastoralist communities. RVF also has an impact on international trade and other agro-industries. The risk of introducing RVF into disease-free countries via the importation of an infected animal or mosquito is real, and the consequent restriction of access to export markets may induce dramatic economic consequences for national and local economies. Despite the important threat of RVF, few studies have been conducted to assess the socio-economic impact of the disease. The 17 studies identified for quantitative analysis in this review relied only on partial cost analysis, with limited reference to mid- and long-term impact, public health or risk mitigation measures. However, the estimated impacts were high (ranging from $5 to $470 million USD losses). To reduce the impact of RVF, early detection and rapid response should be implemented. Comprehensive disease impact studies are required to provide decision-makers with science-based information on the best intervention measure to implement ensuring efficient resource allocation. Through the analysis of RVF socio-economic impact, this scoping study proposes insights into the mechanisms underpinning its often-underestimated importance. This study highlights the need for comparative socio-economic studies to help decision-makers with their choices related to RVF disease management. © 2014 The Authors

The sero-epidemiology of Rift Valley fever in people in the Lake Victoria Basin of western Kenya.

Directory of Open Access Journals (Sweden)

Elizabeth Anne Jessie Cook

2017-07-01

Full Text Available Rift Valley fever virus (RVFV is a zoonotic arbovirus affecting livestock and people. This study was conducted in western Kenya where RVFV outbreaks have not previously been reported. The aims were to document the seroprevalence and risk factors for RVFV antibodies in a community-based sample from western Kenya and compare this with slaughterhouse workers in the same region who are considered a high-risk group for RVFV exposure. The study was conducted in western Kenya between July 2010 and November 2012. Individuals were recruited from randomly selected homesteads and a census of slaughterhouses. Structured questionnaire tools were used to collect information on demographic data, health, and risk factors for zoonotic disease exposure. Indirect ELISA on serum samples determined seropositivity to RVFV. Risk factor analysis for RVFV seropositivity was conducted using multi-level logistic regression. A total of 1861 individuals were sampled in 384 homesteads. The seroprevalence of RVFV in the community was 0.8% (95% CI 0.5-1.3. The variables significantly associated with RVFV seropositivity in the community were increasing age (OR 1.2; 95% CI 1.1-1.4, p<0.001, and slaughtering cattle at the homestead (OR 3.3; 95% CI 1.0-10.5, p = 0.047. A total of 553 slaughterhouse workers were sampled in 84 ruminant slaughterhouses. The seroprevalence of RVFV in slaughterhouse workers was 2.5% (95% CI 1.5-4.2. Being the slaughterman, the person who cuts the animal's throat (OR 3.5; 95% CI 1.0-12.1, p = 0.047, was significantly associated with RVFV seropositivity. This study investigated and compared the epidemiology of RVFV between community members and slaughterhouse workers in western Kenya. The data demonstrate that slaughtering animals is a risk factor for RVFV seropositivity and that slaughterhouse workers are a high-risk group for RVFV seropositivity in this environment. These risk factors have been previously reported in other studies providing further

The sero-epidemiology of Rift Valley fever in people in the Lake Victoria Basin of western Kenya.

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Cook, Elizabeth Anne Jessie; Grossi-Soyster, Elysse Noel; de Glanville, William Anson; Thomas, Lian Francesca; Kariuki, Samuel; Bronsvoort, Barend Mark de Clare; Wamae, Claire Njeri; LaBeaud, Angelle Desiree; Fèvre, Eric Maurice

2017-07-01

Rift Valley fever virus (RVFV) is a zoonotic arbovirus affecting livestock and people. This study was conducted in western Kenya where RVFV outbreaks have not previously been reported. The aims were to document the seroprevalence and risk factors for RVFV antibodies in a community-based sample from western Kenya and compare this with slaughterhouse workers in the same region who are considered a high-risk group for RVFV exposure. The study was conducted in western Kenya between July 2010 and November 2012. Individuals were recruited from randomly selected homesteads and a census of slaughterhouses. Structured questionnaire tools were used to collect information on demographic data, health, and risk factors for zoonotic disease exposure. Indirect ELISA on serum samples determined seropositivity to RVFV. Risk factor analysis for RVFV seropositivity was conducted using multi-level logistic regression. A total of 1861 individuals were sampled in 384 homesteads. The seroprevalence of RVFV in the community was 0.8% (95% CI 0.5-1.3). The variables significantly associated with RVFV seropositivity in the community were increasing age (OR 1.2; 95% CI 1.1-1.4, p<0.001), and slaughtering cattle at the homestead (OR 3.3; 95% CI 1.0-10.5, p = 0.047). A total of 553 slaughterhouse workers were sampled in 84 ruminant slaughterhouses. The seroprevalence of RVFV in slaughterhouse workers was 2.5% (95% CI 1.5-4.2). Being the slaughterman, the person who cuts the animal's throat (OR 3.5; 95% CI 1.0-12.1, p = 0.047), was significantly associated with RVFV seropositivity. This study investigated and compared the epidemiology of RVFV between community members and slaughterhouse workers in western Kenya. The data demonstrate that slaughtering animals is a risk factor for RVFV seropositivity and that slaughterhouse workers are a high-risk group for RVFV seropositivity in this environment. These risk factors have been previously reported in other studies providing further evidence for RVFV

Kanda fault: A major seismogenic element west of the Rukwa Rift (Tanzania, East Africa)

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Vittori, Eutizio; Delvaux, Damien; Kervyn, François

1997-09-01

The NW-SE trending Rukwa Rift, part of the East African Rift System, links the approximately N-S oriented Tanganyika and Nyassa (Malawi) depressions. The rift has a complex half-graben structure, generally interpreted as the result of normal and strike-slip faulting. Morphological and structural data (e.g. fault scarps, faceted spurs, tilting of Quaternary continental deposits, volcanism, seismicity) indicate Late Quaternary activity within the rift. In 1910 an earthquake of M = 7.4 (historically the largest felt in Africa) struck the Rukwa region. The epicentre was located near the Kanda fault, which affects the Ufipa plateau, separating the Rukwa depression from the south-Tanganyika basin. The geomorphic expression of the Kanda fault is a prominent fresh-looking scarp more than 180 km long, from Tunduma to north of Sumbawanga, that strikes roughly NW-SE, and dips constantly northeast. No evidence for horizontal slip was observed. Generally, the active faulting affects a very narrow zone, and is only locally distributed over several subparallel scarps. The height of the scarp progressively decreases towards the northwest, from about 40-50 m to a few metres north of Sumbawanga. Faulted lacustrine deposits exposed in a road cut near Kaengesa were dated as 8340 ± 700 and 13 600 ± 1240 radiocarbon years. These low-energy deposits now hang more than 15 m above the present-day valley floor, suggesting rapid uplift during the Holocene. Due to its high rate of activity in very recent times, the Kanda Fault could have produced the 1910 earthquake. Detailed paleoseismological studies are used to characterize its recent history. In addition, the seismic hazard posed by this fault, which crosses the fast growing town of Sumbawanga, must be seriously considered in urban planning.

Evaluation of positive Rift Valley fever virus formalin-fixed paraffin embedded samples as a source of sequence data for retrospective phylogenetic analysis.

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Mubemba, B; Thompson, P N; Odendaal, L; Coetzee, P; Venter, E H

2017-05-01

Rift Valley fever (RVF), caused by an arthropod borne Phlebovirus in the family Bunyaviridae, is a haemorrhagic disease that affects ruminants and humans. Due to the zoonotic nature of the virus, a biosafety level 3 laboratory is required for isolation of the virus. Fresh and frozen samples are the preferred sample type for isolation and acquisition of sequence data. However, these samples are scarce in addition to posing a health risk to laboratory personnel. Archived formalin-fixed, paraffin-embedded (FFPE) tissue samples are safe and readily available, however FFPE derived RNA is in most cases degraded and cross-linked in peptide bonds and it is unknown whether the sample type would be suitable as reference material for retrospective phylogenetic studies. A RT-PCR assay targeting a 490 nt portion of the structural G N glycoprotein encoding gene of the RVFV M-segment was applied to total RNA extracted from archived RVFV positive FFPE samples. Several attempts to obtain target amplicons were unsuccessful. FFPE samples were then analysed using next generation sequencing (NGS), i.e. Truseq ® (Illumina) and sequenced on the Miseq ® genome analyser (Illumina). Using reference mapping, gapped virus sequence data of varying degrees of shallow depth was aligned to a reference sequence. However, the NGS did not yield long enough contigs that consistently covered the same genome regions in all samples to allow phylogenetic analysis. Copyright © 2017 Elsevier B.V. All rights reserved.

Is the Gop rift oceanic? A reevaluation of the Seychelles-India conjugate margins

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Guan, Huixin; Werner, Philippe; Geoffroy, Laurent

2016-04-01

Gop Rift axis. We propose that the conspicuous buoyant central part of the Gop Rift is likely associated with a continental C-Block as described in a recent paper on conjugated VPMs8, at least in the southern part of the Gop Rift. The crust below the Laxmi basin is probably transitional continental i.e. strongly intruded. West of India and west of the Laxmi Ridge, the transition to the Carlsberg Basin occurs along a clearly-expressed transform fault, not through an extended and thinned continental margin. We reinterpret the whole system based on those observations and propositions, giving some explanations on controversial magnetic anomalies based on similar observations from the southern Atlantic Ocean. 1: Collier et al., 2008. Age of the Seychelles-India break-up. Earth and Planetary Science Letters. 2: Minshull et al., 2008. The relationship between riftingand magmatism in the northeastern Arabian Sea. Nature Geoscience. 3 : Armitage et al., 2010. The importance of rift history for volcanic margin. Nature. 4 : Krishna et al., 2006. Nature of the crust in the Laxmi Basin (14 degrees-20 degrees N), western continental margin of India. Tectonics. 5 : Misra et al., 2015. Repeat ridge jumps and microcontinent separation: insights from NE Arabian Sea. Marine and Petroleum Geology. 6 : Biswas, 1982. Rift basins in the western margin of India and their hydrocarbon prospects. Bull. Am. Assoc. Pet. Geol. 7 : Chatterjee et al., 2013. The longest voyage: Tectonic, magmatic, and paleoclimatic evolution of the Indian plate during its northward flight from Gondwana to Asia. Gondwana Research. 8 : Geoffroy et al., 2015. Volcanic passive margins: anotherway to break up continents. Scientific Reports.

An interdisciplinary approach for groundwater management in area contaminated by fluoride in East African Rift System

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Da Pelo, Stefania; Melis, M. Teresa; Dessì, Francesco; Pistis, Marco; Funedda, Antonio; Oggiano, Giacomo; Carletti, Alberto; Soler Gil, Albert; Barbieri, Manuela; Pittalis, Daniele; Ghiglieri, Giorgio

2017-04-01

Groundwater is the main source of fresh water supply for most of the rural communities in Africa (approximately 75% of Africans has confidence in groundwater as their major source of drinking water). Many African countries has affected by high fluoride concentration in groundwater (up to 90 mg/L), generating the contamination of waters, soils and food, in particular in the eastern part of the continent. It seems that fluoride concentration is linked to geology of the Rift Valley: geogenic occurrence of fluoride is often connected to supergenic enrichment due to the weathering of alkaline volcanic rocks, fumaric gases and presence of thermal waters. The H2020 project FLOWERED (de-FLuoridation technologies for imprOving quality of WatEr and agRo-animal products along the East African Rift Valley in the context of aDaptation to climate change) wish to address environmental and health (human and animal) issues associated to the fluoride contamination in the African Rift Valley, in particular in three case study area located in Ethiopia, Tanzania and Kenya. FLOWERED aims to develop an integrated, sustainable and participative water and agriculture management at a cross-boundary catchment scale through a strong interdisciplinary research approach. It implies knowledge of geology, hydrogeology, mineralogy, geochemistry, agronomy, crop and animal sciences, engineering, technological sciences, data management and software design, economics and communication. The proposed approach is based on a detailed knowledge of the hydrogeological setting, with the identification and mapping of the specific geological conditions of water contamination and its relation with the different land uses. The East African Rift System (EARS) groundwater circulation and storage, today already poorly understood, is characterized by a complex arrangement of aquifers. It depends on the type of porosity and permeability created during and after the rock formation, and is strongly conditioned by the

Bookshelf faulting and transform motion between rift segments of the Northern Volcanic Zone, Iceland

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Green, R. G.; White, R. S.; Greenfield, T. S.

2013-12-01

Plate spreading is segmented on length scales from 10 - 1,000 kilometres. Where spreading segments are offset, extensional motion has to transfer from one segment to another. In classical plate tectonics, mid-ocean ridge spreading centres are offset by transform faults, but smaller 'non-transform' offsets exist between slightly overlapping spreading centres which accommodate shear by a variety of geometries. In Iceland the mid-Atlantic Ridge is raised above sea level by the Iceland mantle plume, and is divided into a series of segments 20-150 km long. Using microseismicity recorded by a temporary array of 26 three-component seismometers during 2009-2012 we map bookshelf faulting between the offset Askja and Kverkfjöll rift segments in north Iceland. The micro-earthquakes delineate a series of sub-parallel strike-slip faults. Well constrained fault plane solutions show consistent left-lateral motion on fault planes aligned closely with epicentral trends. The shear couple across the transform zone causes left-lateral slip on the series of strike-slip faults sub-parallel to the rift fabric, causing clockwise rotations about a vertical axis of the intervening rigid crustal blocks. This accommodates the overall right-lateral transform motion in the relay zone between the two overlapping volcanic rift segments. The faults probably reactivated crustal weaknesses along the dyke intrusion fabric (parallel to the rift axis) and have since rotated ˜15° clockwise into their present orientation. The reactivation of pre-existing rift-parallel weaknesses is in contrast with mid-ocean ridge transform faults, and is an important illustration of a 'non-transform' offset accommodating shear between overlapping spreading segments.

Groundwater quality in Coachella Valley, California

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Dawson, Barbara J. Milby; Belitz, Kenneth

2012-01-01

Groundwater provides more than 40 percent of California’s drinking water. To protect this vital resource, the State of California created the Groundwater Ambient Monitoring and Assessment (GAMA) Program. The Priority Basin Project of the GAMA Program provides a comprehensive assessment of the State’s groundwater quality and increases public access to groundwater-quality information. Coachella Valley is one of the study areas being evaluated. The Coachella study area is approximately 820 square miles (2,124 square kilometers) and includes the Coachella Valley groundwater basin (California Department of Water Resources, 2003). Coachella Valley has an arid climate, with average annual rainfall of about 6 inches (15 centimeters). The runoff from the surrounding mountains drains to rivers that flow east and south out of the study area to the Salton Sea. Land use in the study area is approximately 67 percent (%) natural, 21% agricultural, and 12% urban. The primary natural land cover is shrubland. The largest urban areas are the cities of Indio and Palm Springs (2010 populations of 76,000 and 44,000, respectively). Groundwater in this basin is used for public and domestic water supply and for irrigation. The main water-bearing units are gravel, sand, silt, and clay derived from surrounding mountains. The primary aquifers in Coachella Valley are defined as those parts of the aquifers corresponding to the perforated intervals of wells listed in the California Department of Public Health database. Public-supply wells in Coachella Valley are completed to depths between 490 and 900 feet (149 to 274 meters), consist of solid casing from the land surface to a depth of 260 to 510 feet (79 to 155 meters), and are screened or perforated below the solid casing. Recharge to the groundwater system is primarily runoff from the surrounding mountains, and by direct infiltration of irrigation. The primary sources of discharge are pumping wells, evapotranspiration, and underflow to

Speciation of selected trace elements in three Ethiopian Rift Valley Lakes (Koka, Ziway, and Awassa) and their major inflows

International Nuclear Information System (INIS)

Masresha, Alemayehu E.; Skipperud, Lindis; Rosseland, Bjorn Olav; Zinabu, G.M.; Meland, Sondre; Teien, Hans-Christian; Salbu, Brit

2011-01-01

The Ethiopian Rift Valley Lakes (ERVLs) are water resources which have considerable environmental, economic and cultural importance. However, there is an increasing concern that increasing human activities around these lakes and their main inflows can result in increased contamination of these water bodies. Information on total concentrations of some trace elements is available for these lakes and their inflows; however, data on the trace element speciation is lacking. Therefore, the objective of this study was to determine the low molecular mass (LMM) trace element species and also, evaluate the influence of flooding episodes on the LMM trace element fractions. At-site size and charge fractionation system was used for sampling of water from the lakes Koka, Ziway and Awassa and their main inflows during the dry and wet seasons. The results showed that chromium (Cr), manganese (Mn), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), and lead (Pb) in Lake Koka and its inflows as well as in Lake Ziway were predominantly present as HMM (high molecular mass, i.e., > 10 kDa) forms, while arsenic (As), selenium (Se), cadmium (Cd) were more mobile during the dry season. In Lake Awassa, all except Cr and Mn were predominantly found as LMM species (low molecular mass, i.e. < 10 kDa) which can be attributed to the high concentrations of LMM DOC (dissolved organic carbon). During the wet season, results from the Lake Koka and its inflows showed that all trace elements were predominantly associated with HMM forms such as colloids and particles, demonstrating that the mobility of elements was reduced during the wet season. The colloidal fraction of elements such as Cr, Ni, and Cd was also correlated with dissolved Fe. As the concentration of LMM trace element species are very low, the mobility, biological uptake and the potential environmental impact should be low.

Reverse-phase phosphoproteome analysis of signaling pathways induced by Rift valley fever virus in human small airway epithelial cells.

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Taissia G Popova

Full Text Available Rift valley fever virus (RVFV infection is an emerging zoonotic disease endemic in many countries of sub-Saharan Africa and in Egypt. In this study we show that human small airway epithelial cells are highly susceptible to RVFV virulent strain ZH-501 and the attenuated strain MP-12. We used the reverse-phase protein arrays technology to identify phosphoprotein signaling pathways modulated during infection of cultured airway epithelium. ZH-501 infection induced activation of MAP kinases (p38, JNK and ERK and downstream transcriptional factors [STAT1 (Y701, ATF2 (T69/71, MSK1 (S360 and CREB (S133]. NF-κB phosphorylation was also increased. Activation of p53 (S15, S46 correlated with the increased levels of cleaved effector caspase-3, -6 and -7, indicating activation of the extrinsic apoptotic pathway. RVFV infection downregulated phosphorylation of a major anti-apoptotic regulator of survival pathways, AKT (S473, along with phosphorylation of FOX 01/03 (T24/31 which controls cell cycle arrest downstream from AKT. Consistent with this, the level of apoptosis inhibitor XIAP was decreased. However, the intrinsic apoptotic pathway marker, caspase-9, demonstrated only a marginal activation accompanied by an increased level of the inhibitor of apoptosome formation, HSP27. Concentration of the autophagy marker, LC3B, which often accompanies the pro-survival signaling, was decreased. Cumulatively, our analysis of RVFV infection in lung epithelium indicated a viral strategy directed toward the control of cell apoptosis through a number of transcriptional factors. Analyses of MP-12 titers in challenged cells in the presence of MAPK inhibitors indicated that activation of p38 represents a protective cell response while ERK activation controls viral replication.

Identification of suitable areas for the occurrence of Rift Valley fever outbreaks in Spain using a multiple criteria decision framework.

Science.gov (United States)

Sánchez-Vizcaíno, Fernando; Martínez-López, Beatriz; Sánchez-Vizcaíno, José Manuel

2013-07-26

Rift Valley fever (RVF) is a mosquito-borne viral disease that may produce a considerable impact on the economy in affected countries. In the last decades, the geographic distribution of RVF virus has increased including most of the countries in Africa, Arabia Saudi and Yemen. This situation has raised the concerns regarding its potential introduction in the European Union (EU) countries where the high number of susceptible species and competent vectors may contribute to the spread of the disease and challenge its rapid control. Thus, the identification of the areas and time periods with highest suitability for RVF outbreak occurrence would be useful for improving the early detection and rapid response of the disease into free countries. The objective of this study was to identify suitable areas for the occurrence of RVF outbreaks in Spain using a multiple criteria decision making model based on weighted linear combination of factors in geographical information systems (GIS). To the best of the author's knowledge this is the first comprehensive GIS-based framework that provides risk maps for RVF suitability in an EU country. Spanish zones with the highest suitability for RVF were concentrated in the regions of Extremadura, south-western Castile and Leon, eastern Galicia, Asturias, Cantabria, Basque Country, northern-central and southern region of Andalusia and in the Balearic Islands. October and May were the most suitable months for RVF outbreak occurrence. Methods and results presented here may be useful to target risk-based surveillance strategies and to more cost-effectively control potential RVFV incursions into Spain. Copyright © 2013 Elsevier B.V. All rights reserved.

The crustal characteristics at syn- and/or post-rifting in eastern Shikoku basin by seismic reflection survey

Science.gov (United States)

Yamashita, M.; Takahashi, N.; Kodaira, S.; Takizawa, K.; No, T.; Miura, S.; Kaneda, Y.

2008-12-01

Imaging of the arc-backarc transition zone is important in relation to the backarc opening process. Shikoku Basin locates between the Kyushu-Palau Ridge and the Izu-Ogasawara Arc, which is an important area to reveal the opening evolution of the backarc basins as a part of the growth process of the Philippine Sea. The Shikoku Basin was in the backarc rifting and spreading stage during about 30-15 Ma (e.g. Okino et al., 1994). High P-wave velocity lower crust is identified in arc-backarc transition zone by refraction survey using OBSs (Takahashi et al., 2007). Japan Agency for Marine-Earth Science and Technology (JAMSTEC) carried out multi-channel seismic reflection (MCS) survey using 12,000 cu.in. air gun and 5 km streamer with 204 ch hydrophones in the Izu-Ogasawara region since 2004. We extracted and mapped the crustal characteristics from poststack and prestack depth migrated profiles. According to obtained profiles, the deformation structure with share component is recognized in arc-backarc transition zone, which located eastern side of Shikoku Basin from Zenisu Ridge to about 500 km south. The maximum width of this deformation zone is about 100 km. The relative displacement of horizon is little; however, it is strongly deformed from upper crust beneath seafloor. This deformation zone indicates the post- rifting activity in east side of Shikoku Basin. On the other hand, some knolls are indicated along the en- echelon arrangement from Izu-Ogasawara arc. Ishizuka et al. (2003) reported post-rifting volcanism with Miocene age in en-echelon arrangement. A part of these knolls are estimated to penetrate at syn-rifting and/or post-rifting stage in backarc opening. By comparing the both side of arc-backarc transition zone, we elucidate syn- and post-rifting effect in Shikoku Basin. We also carried out high density MCS surveys in Shikoku Basin in order to IODP proposal site for reconstruction of magmatic processes since Oligocene in rear arc. In this survey, we use new

Controls of inherited lithospheric heterogeneity on rift linkage: Numerical and analog models of interaction between the Kenyan and Ethiopian rifts across the Turkana depression

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Brune, Sascha; Corti, Giacomo; Ranalli, Giorgio

2017-09-01

Inherited rheological structures in the lithosphere are expected to have large impact on the architecture of continental rifts. The Turkana depression in the East African Rift connects the Main Ethiopian Rift to the north with the Kenya rift in the south. This region is characterized by a NW-SE trending band of thinned crust inherited from a Mesozoic rifting event, which is cutting the present-day N-S rift trend at high angle. In striking contrast to the narrow rifts in Ethiopia and Kenya, extension in the Turkana region is accommodated in subparallel deformation domains that are laterally distributed over several hundred kilometers. We present both analog experiments and numerical models that reproduce the along-axis transition from narrow rifting in Ethiopia and Kenya to a distributed deformation within the Turkana depression. Similarly to natural observations, our models show that the Ethiopian and Kenyan rifts bend away from each other within the Turkana region, thus forming a right-lateral step over and avoiding a direct link to form a continuous N-S depression. The models reveal five potential types of rift linkage across the preexisting basin: three types where rifts bend away from the inherited structure connecting via a (1) wide or (2) narrow rift or by (3) forming a rotating microplate, (4) a type where rifts bend towards it, and (5) straight rift linkage. The fact that linkage type 1 is realized in the Turkana region provides new insights on the rheological configuration of the Mesozoic rift system at the onset of the recent rift episode.

Syn-rift unconformities punctuating the lower-middle Cambrian transition in the Atlas Rift, Morocco

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Álvaro, J. Javier; Ezzouhairi, Hassan; Clausen, Sébastien; Ribeiro, M. Luisa; Solá, Rita

2015-04-01

The Cambrian Tamdroust and Bab n'Ali Volcanic Complexes represent two magmatic episodes developed in the latest Ediacaran-Cambrian Atlas Rift of Morocco. Their rifting pulses were accompanied by accumulation of volcanosedimentary edifices (dominated by effusive lava flows in the former and explosive acidic aprons in the latter) associated with active tilting and uplift. Sealing of their peneplaned horst-and-graben palaeotopographies led to the onset of distinct onlapping geometries and angular discordances capping eroded basements ranging from the Ediacaran Ouarzazate Supergroup to the Cambrian Asrir Formation. Previous interpretations of these discordances as pull-apart or compressive events are revised here and reinterpreted in an extensional (rifting) context associated with active volcanism. The record of erosive unconformities, stratigraphic gaps, condensed beds and onlapping patterns across the traditional "lower-middle Cambrian" (or Cambrian Series 2-3) transition of the Atlas Rift must be taken into consideration for global chronostratigraphic correlation based on their trilobite content.

Kinematic evolution of the southwestern Arabian continental margin: implications for the origin of the Red Sea

Science.gov (United States)

Voggenreiter, W.; Hötzl, H.

The tectonic and magnetic evolution of the Jizan coastal plain (Tihama Asir) in southwest Arabia was dominated by SW-NE lithospheric extension related to the development of the Red Sea Rift. A well-exposed, isotopically-dated succession of magmatic rocks (Jizan Group volcanics, Tihama Asir Magmatic Complex) allows a kinematic analysis for this part of the Arabian Red Sea margin. A mafic dyke swarm and several generations of roughly NW-trending normal faults characterized the continental rift stage from Oligocene to early Miocene time. Major uplift of the Arabian graben shoulder probably began about 14 Ma ago. By this time, extension and magmatism ceased in the Jizan area and were followed by an approximately 10 Ma interval of tectonic and magmatic quiescence. A second phase of extension began in the Pliocene and facilitated a vast outpouring of alkaliolivine basalts on the coastal plain. The geometry of faulting in the Jizan area supports a Wernicke-type simple-shear mechanism of continental rifting for the southern Arabian continental margin of the Red Sea.

[Feeding pattern of Rift Valley Fever virus vectors in Senegal. Implications in the disease epidemiology].

Science.gov (United States)

Ba, Y; Diallo, D; Dia, I; Diallo, M

2006-10-01

During the rainy season 2003, an entomological survey was undertaken in the Sahelian bioclimatic zone of the Ferlo area in northern Senegal, in order to evaluate the degree of interaction between Rift valley fever (RVF) virus vectors and domestic animals and to determine the role of natural vertebrate hosts in the transmission and maintenance cycle. The study of vector-host contact was carried out under bed net traps using man, cow, sheep, chicken as bait whereas the RVFV vectors-vertebrate host interactions were studied through the analysis by an ELISA technique of the origin of the blood meals from naturally engorged females collected by aspiration. Blood meals sources were determined using a set of eight antibodies. Overall, the different known RVFV vectors (Culex poicilipes, Aedes vexans and Aedes ochraceus) were opportunistic although the bovine-baited net was, as far the more effective trap with 53.6% of collected mosquitoes. It was followed by the sheep-baited net (16.7%), man-baited net (12.6%) and chicken-baited net (11.6%). The more effectiveness of the bovine-baited net confirms the degree of implication of this host in RVF epidemiology. The study of vector-hosts interactions in nature showed that among the 1,112 mosquito blood meals tested, 701 were identified of which 693 were from Aedes vexans. The percentage of non-reacting blood meal was 36.7% whereas 16.9 % of the blood meals were taken at least on two vertebrate hosts. Overall, 53.2% of the blood meals from Ae. vexans were taken on equine, 18.6% on bovines, 7.1% on sheep and 0.6% on human. No blood meal was taken on rodent. The greatest diversity was observed in August. These host feedings patterns show that although equine is known to play a minor role in RVF epidemiology a thorough attention should be made to this host with regard to the percentage of blood meals taken in this host. The low percentage of blood meals taken on human could probably explain the low human infection rate observed up

Application of multivariate statistical analyses in the interpretation of geochemical behaviour of uranium in phosphatic rocks in the Red Sea, Nile Valley and Western Desert, Egypt

International Nuclear Information System (INIS)

El-Arabi, A.M.Abd El-Gabar M.; Khalifa, Ibrahim H.

2002-01-01

Factor and cluster analyses as well as the Pearson correlation coefficient have been applied to geochemical data obtained from phosphorite and phosphatic rocks of Duwi Formation exposed at the Red Sea coast, Nile Valley and Western Desert. Sixty-six samples from a total of 71 collected samples were analysed for SiO 2 , TiO 2 , Al 2 O 3 , Fe 2 O 3 , CaO, MgO, Na 2 O, K 2 O, P 2 O 5 , Sr, U and Pb by XRF and their mineral constituents were determined by the use of XRD techniques. In addition, the natural radioactivity of the phosphatic samples due to their uranium, thorium and potassium contents was measured by gamma-spectrometry.The uranium content in the phosphate rocks with P 2 O 5 >15% (average of 106.6 ppm) is higher than in rocks with P 2 O 5 2 O 5 and CaO, whereas it is not related to changes in SiO 2 , TiO 2 , Al 2 O 3 , Fe 2 O 3 , MgO, Na 2 O and K 2 O concentrations.Factor analysis and the Pearson correlation coefficient revealed that uranium behaves geochemically in different ways in the phosphatic sediments and phosphorites in the Red Sea, Nile Valley and Western Desert. In the Red Sea and Western Desert phosphorites, uranium occurs mainly in oxidized U 6+ state where it seems to be fixed by the phosphate ion, forming secondary uranium phosphate minerals such as phosphuranylite.In the Nile Valley phosphorites, ionic substitution of Ca 2+ by U 4+ is the main controlling factor in the concentration of uranium in phosphate rocks. Moreover, fixation of U 6+ by phosphate ion and adsorption of uranium on phosphate minerals play subordinate roles

Host selection patterns of Culex tarsalis (Diptera: Culicidae) at wetlands near the Salton Sea, Coachella Valley, California, 1998-2002.

Science.gov (United States)

Reisen, William K; Lothrop, Hugh D; Thiemann, Tara

2013-09-01

The bloodmeal hosts used by Culex tarsalis Coquillett collected along the Salton Sea in Coachella Valley, CA, during 1998-2002 were identified using sequences of the cytochrome c oxidase I gene identified from Barcode of Life database. Overall, 265 (83.3%) of 318 bloodmeals were identified, of which 76.6% fed on birds, 18.1% on mammals, and 5.3% on reptiles. Forty-seven different hosts were identified, none of which comprised > 12.5% of the total. Although Cx. tarsalis exhibits specific host-seeking flight patterns, bloodmeals seemed to be acquired opportunistically, thereby limiting potential arbovirus transmission efficiency in species-rich environments.

Deepening, and repairing, the metabolic rift.

Science.gov (United States)

Schneider, Mindi; McMichael, Philip

2010-01-01

This paper critically assesses the metabolic rift as a social, ecological, and historical concept describing the disruption of natural cycles and processes and ruptures in material human-nature relations under capitalism. As a social concept, the metabolic rift presumes that metabolism is understood in relation to the labour process. This conception, however, privileges the organisation of labour to the exclusion of the practice of labour, which we argue challenges its utility for analysing contemporary socio-environmental crises. As an ecological concept, the metabolic rift is based on outmoded understandings of (agro) ecosystems and inadequately describes relations and interactions between labour and ecological processes. Historically, the metabolic rift is integral to debates about the definitions and relations of capitalism, industrialism, and modernity as historical concepts. At the same time, it gives rise to an epistemic rift, insofar as the separation of the natural and social worlds comes to be expressed in social thought and critical theory, which have one-sidedly focused on the social. We argue that a reunification of the social and the ecological, in historical practice and in historical thought, is the key to repairing the metabolic rift, both conceptually and practically. The food sovereignty movement in this respect is exemplary.

Anthropogenic Influence On Groundwater Quality In Jericho and And Adjoining Wadis (Lower Jordan Valley, Palestine)

Science.gov (United States)

Geyer, S.; Khayat, S.; Roediger, T.; Siebert, C.

2008-12-01

The Lower Jordan Valley is part of the Jordan-Dead Sea Rift. The graben is filled by sedmiments of limnological and marine origin. Towards the Dead Sea, the occurance of gipseous and salty sediments on the valley floor increase. The southern part of the Lower Jordan Valley, where the city of Jericho is situated, is an arid area (SMART-project, is to understand the vulnerability of the Jericho groundwater aquifers in connection with lowering the groundwater table by overexploitation and the intensively use of pesticides Jericho and its vicinity are of most importance for the Palestinians. However, beside the about 25,000 residents, the tourism industry and the vital agriculture depend on sufficient and expoitable fresh water resources. Because the demand of water is increasing, overexpoitaion takes place. Due to over extraction of groundwater a huge depression cone is evolving during the dry season which is filled up again according to the groundwater recharge in the rainy season. Concomitantly, depression cone in the fresh water aquifers leads to an infiltration of the surrounding saltwater. The amount of saltwater which infiltrates into the freshwater resource was calculated by different stable isotope methods (d2H, d18O) and hydrochemical analyses of wellwater. The agriculture is main consumer of groundwater - over 60% of the pumped water is used for inefficient irrigation. Additionally, an intensive use of pesticides in concentrated liquid and gaseous forms for vegetable gardening hold the danger to pollute the groundwater via irrigation return flow. This return flow most probably endangers the quality of the water resource, because shallow wells nearby extract it directly from the underground. However, one result of the first screening campaign concerning pesticide remnants in the groundwater wells of Jericho, just traces have been detected. Thus, the higher amount of chemicals is retained by the soil during infiltration of irrigated water. The detected low

Arabian Plate Deformation: The role of inherited structures in the localization of strain in the Red Sea extensional system

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Aldaajani, T.; Furlong, K.; Malservisi, R.

2017-12-01

The Red Sea rift structural architecture changes dramatically along strike from narrow localized spreading (with creation of new oceanic crust) in the south to asymmetrical diffuse extension north of 21 ° latitude. The region of diffuse extension falls within a triangle that is bounded to the east by the Sarhan graben, (a Cenozoic failed rift), to the west by the northern Red Sea Rift, and to the south by the Makkah-Madinah-Nafud (MMN) volcanic line. Geological observations appear to show that tectonic stresses acting on inherited structures within the NW Arabian margin are associated with the region of diffuse extension. In contrast, in the southern Red Sea, a single strong block within the SW Arabian margin led to localize the extension there. Using current velocities from more than 30 GNSS stations distributed within the Arabian plate, we are able to map its rigidity and the distribution of strain along the plate margin. The data show that the transition between the two styles of extension within the Red Sea (crustal accretion vs crustal extension) corresponds with a transition between rigid behavior and diffuse extension within the Arabian Plate. This suggests that the preexisting structures within the Arabian plate play a significant role in the style of extension along the Red Sea margin.

Deposition and alteration of carbonaceous series within a Neotethyan rift at the western boundary of the Arabian plate: The late Permian Um Irna Formation, NW Jordan, a petroleum system

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Dill, H.G.; Kus, J. [Federal Institute for Geosciences and Natural Resources, P.O. Box 51 01 53 D-30631 Hannover (Germany); Bechtel, A.; Gratzer, R. [Department of Applied Geosciences and Geophysics, University of Leoben, Peter Tunner Strasse 5, A-8700 Leoben (Austria); Abu Hamad, A.M.B. [Geology Department, University of Jordan, Amman 11942 (Jordan)

2010-01-07

During the late Permian (Kungurian to Kazanian) a Neotethyan rift basin evolved at the western boundary of the Arabian Plate, in what is called today the Dead Sea Valley of western Jordan. The break-up of Pangaea was accompanied by low-sinuosity sandy braided- to meandering-fluvial drainage systems which were fed by the uplift of the Arabian Shield and by poorly aerated swamps and ponds that concentrated plant debris of the Cathaysian floral province in the Um Irna Formation. These proximal wet fan sediments are overlain by a dry fan characterized by extensive reddish floodplain deposits, anastomosing channel systems and paleosols. The wet fan is underlain by Cambrian sandstones. These units serve as the top and bottom seals of the OM-bearing system of the Um Irna Formation. The sedimentary rocks of the OM-bearing Um Irna Formation underwent supergene, diagenetic and epigenetic hydrothermal alteration under an elevated geothermal gradient. The temperature increased from the time of deposition of the wet to the time of deposition of the dry fan and caused remobilization of manganese already pre-concentrated in the Cambrian footwall rocks of the rift basin. The anomalous heat regime may be accounted for as a predecessor stage of the Dead Sea Rift which is still active today. Oil seeps are found along faults and fractures near this deep-seated lineamentary fault zone. The deposition and alteration of the organic matter in this late Permian rift are of great consequence for oil generation in the region. Organic petrographic investigations revealed that organic-rich terrestrial carbonaceous and coal rich sediments of mainly of type III kerogen are dominant in the Um Irna Formation. In addition, aquatic liptinite rich sedimentary input (fresh water lake and/or lacustrine swamp) of type I kerogen is also noted. Coal derived organic matter occurs in the form of coaly particles with ranks from subbituminous A to high volatile bituminous C. Higher plant-derived macerals as

Fracture patterns of the drainage basin of Wadi Dahab in relation to tectonic-landscape evolution of the Gulf of Aqaba - Dead Sea transform fault

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Shalaby, Ahmed

2017-10-01

Crustal rifting of the Arabian-Nubian Shield and formation of the Afro-Arabian rifts since the Miocene resulted in uplifting and subsequent terrain evolution of Sinai landscapes; including drainage systems and fault scarps. Geomorphic evolution of these landscapes in relation to tectonic evolution of the Afro-Arabian rifts is the prime target of this study. The fracture patterns and landscape evolution of the Wadi Dahab drainage basin (WDDB), in which its landscape is modeled by the tectonic evolution of the Gulf of Aqaba-Dead Sea transform fault, are investigated as a case study of landscape modifications of tectonically-controlled drainage systems. The early developed drainage system of the WDDB was achieved when the Sinai terrain subaerially emerged in post Eocene and initiation of the Afro-Arabian rifts in the Oligo-Miocene. Conjugate shear fractures, parallel to trends of the Afro-Arabian rifts, are synthesized with tensional fracture arrays to adapt some of inland basins, which represent the early destination of the Sinai drainage systems as paleolakes trapping alluvial sediments. Once the Gulf of Aqaba rift basin attains its deeps through sinistral movements on the Gulf of Aqaba-Dead Sea transform fault in the Pleistocene and the consequent rise of the Southern Sinai mountainous peaks, relief potential energy is significantly maintained through time so that it forced the Pleistocene runoffs to flow via drainage systems externally into the Gulf of Aqaba. Hence the older alluvial sediments are (1) carved within the paleolakes by a new generation of drainage systems; followed up through an erosional surface by sandy- to silty-based younger alluvium; and (2) brought on footslopes of fault scarps reviving the early developed scarps and inselbergs. These features argue for crustal uplifting of Sinai landscapes syn-rifting of the Gulf of Aqaba rift basin. Oblique orientation of the Red Sea-Gulf of Suez rift relative to the WNW-trending Precambrian Najd faults; and

Population genetics of two key mosquito vectors of Rift Valley Fever virus reveals new insights into the changing disease outbreak patterns in Kenya.

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David P Tchouassi

2014-12-01

Full Text Available Rift Valley fever (RVF outbreaks in Kenya have increased in frequency and range to include northeastern Kenya where viruses are increasingly being isolated from known (Aedes mcintoshi and newly-associated (Ae. ochraceus vectors. The factors contributing to these changing outbreak patterns are unclear and the population genetic structure of key vectors and/or specific virus-vector associations, in particular, are under-studied. By conducting mitochondrial and nuclear DNA analyses on >220 Kenyan specimens of Ae. mcintoshi and Ae. ochraceus, we uncovered high levels of vector complexity which may partly explain the disease outbreak pattern. Results indicate that Ae. mcintoshi consists of a species complex with one of the member species being unique to the newly-established RVF outbreak-prone northeastern region of Kenya, whereas Ae. ochraceus is a homogeneous population that appears to be undergoing expansion. Characterization of specimens from a RVF-prone site in Senegal, where Ae. ochraceus is a primary vector, revealed direct genetic links between the two Ae. ochraceus populations from both countries. Our data strongly suggest that unlike Ae. mcintoshi, Ae. ochraceus appears to be a relatively recent, single 'introduction' into Kenya. These results, together with increasing isolations from this vector, indicate that Ae. ochraceus will likely be of greater epidemiological importance in future RVF outbreaks in Kenya. Furthermore, the overall vector complexity calls into question the feasibility of mosquito population control approaches reliant on genetic modification.

Population Genetics of Two Key Mosquito Vectors of Rift Valley Fever Virus Reveals New Insights into the Changing Disease Outbreak Patterns in Kenya

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Tchouassi, David P.; Bastos, Armanda D. S.; Sole, Catherine L.; Diallo, Mawlouth; Lutomiah, Joel; Mutisya, James; Mulwa, Francis; Borgemeister, Christian; Sang, Rosemary; Torto, Baldwyn

2014-01-01

Rift Valley fever (RVF) outbreaks in Kenya have increased in frequency and range to include northeastern Kenya where viruses are increasingly being isolated from known (Aedes mcintoshi) and newly-associated (Ae. ochraceus) vectors. The factors contributing to these changing outbreak patterns are unclear and the population genetic structure of key vectors and/or specific virus-vector associations, in particular, are under-studied. By conducting mitochondrial and nuclear DNA analyses on >220 Kenyan specimens of Ae. mcintoshi and Ae. ochraceus, we uncovered high levels of vector complexity which may partly explain the disease outbreak pattern. Results indicate that Ae. mcintoshi consists of a species complex with one of the member species being unique to the newly-established RVF outbreak-prone northeastern region of Kenya, whereas Ae. ochraceus is a homogeneous population that appears to be undergoing expansion. Characterization of specimens from a RVF-prone site in Senegal, where Ae. ochraceus is a primary vector, revealed direct genetic links between the two Ae. ochraceus populations from both countries. Our data strongly suggest that unlike Ae. mcintoshi, Ae. ochraceus appears to be a relatively recent, single 'introduction' into Kenya. These results, together with increasing isolations from this vector, indicate that Ae. ochraceus will likely be of greater epidemiological importance in future RVF outbreaks in Kenya. Furthermore, the overall vector complexity calls into question the feasibility of mosquito population control approaches reliant on genetic modification. PMID:25474018

Nonstructural NSs protein of rift valley fever virus interacts with pericentromeric DNA sequences of the host cell, inducing chromosome cohesion and segregation defects.

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Mansuroglu, Z; Josse, T; Gilleron, J; Billecocq, A; Leger, P; Bouloy, M; Bonnefoy, E

2010-01-01

Rift Valley fever virus (RVFV) is an emerging, highly pathogenic virus; RVFV infection can lead to encephalitis, retinitis, or fatal hepatitis associated with hemorrhagic fever in humans, as well as death, abortions, and fetal deformities in animals. RVFV nonstructural NSs protein, a major factor of the virulence, forms filamentous structures in the nuclei of infected cells. In order to further understand RVFV pathology, we investigated, by chromatin immunoprecipitation, immunofluorescence, fluorescence in situ hybridization, and confocal microscopy, the capacity of NSs to interact with the host genome. Our results demonstrate that even though cellular DNA is predominantly excluded from NSs filaments, NSs interacts with some specific DNA regions of the host genome such as clusters of pericentromeric gamma-satellite sequence. Targeting of these sequences by NSs was correlated with the induction of chromosome cohesion and segregation defects in RVFV-infected murine, as well as sheep cells. Using recombinant nonpathogenic virus rZHDeltaNSs210-230, expressing a NSs protein deleted of its region of interaction with cellular factor SAP30, we showed that the NSs-SAP30 interaction was essential for NSs to target pericentromeric sequences, as well as for induction of chromosome segregation defects. The effect of RVFV upon the inheritance of genetic information is discussed with respect to the pathology associated with fetal deformities and abortions, highlighting the main role played by cellular cofactor SAP30 on the establishment of NSs interactions with host DNA sequences and RVFV pathogenesis.

Inter-epidemic abundance and distribution of potential mosquito vectors for Rift Valley fever virus in Ngorongoro district, Tanzania

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Clement N. Mweya

2015-01-01

Full Text Available Background: Rift Valley fever (RVF is a mosquito-borne viral zoonosis that primarily affects ruminants but also has the capacity to infect humans. Objective: To determine the abundance and distribution of mosquito vectors in relation to their potential role in the virus transmission and maintenance in disease epidemic areas of Ngorongoro district in northern Tanzania. Methods: A cross-sectional entomological investigation was carried out before the suspected RVF outbreak in October 2012. Mosquitoes were sampled both outdoors and indoors using the Centre for Disease Control (CDC light traps and Mosquito Magnets baited with attractants. Outdoor traps were placed in proximity with breeding sites and under canopy in banana plantations close to the sleeping places of animals. Results: A total of 1,823 mosquitoes were collected, of which 87% (N=1,588 were Culex pipiens complex, 12% (N=226 Aedes aegypti, and 0.5% (N=9 Anopheles species. About two-thirds (67%; N=1,095 of C. pipiens complex and nearly 100% (N=225 of A. aegypti were trapped outdoors using Mosquito Magnets. All Anopheles species were trapped indoors using CDC light traps. There were variations in abundance of C. pipiens complex and A. aegypti among different ecological and vegetation habitats. Over three quarters (78% of C. pipiens complex and most (85% of the A. aegypti were trapped in banana and maize farms. Both C. pipiens complex and A. aegypti were more abundant in proximity with cattle and in semi-arid thorn bushes and lower Afro-montane. The highest number of mosquitoes was recorded in villages that were most affected during the RVF epidemic of 2007. Of the tested 150 pools of C. pipiens complex and 45 pools of A. aegypti, none was infected with RVF virus. Conclusions: These results provide insights into unique habitat characterisation relating to mosquito abundances and distribution in RVF epidemic-prone areas of Ngorongoro district in northern Tanzania.

Statistical modeling of the abundance of vectors of West African Rift Valley fever in Barkédji, Senegal.

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Cheikh Talla

Full Text Available Rift Valley fever is an emerging mosquito-borne disease that represents a threat to human and animal health. The exophilic and exophagic behavior of the two main vector in West Africa (Aedes vexans and Culex poicilipes, adverse events post-vaccination, and lack of treatment, render ineffective the disease control. Therefore it is essential to develop an information system that facilitates decision-making and the implementation of adaptation strategies. In East Africa, RVF outbreaks are linked with abnormally high rainfall, and can be predicted up to 5 months in advance by modeling approaches using climatic and environmental parameters. However, the application of these models in West Africa remains unsatisfactory due to a lack of data for animal and human cases and differences in the dynamics of the disease emergence and the vector species involved in transmission. Models have been proposed for West Africa but they were restricted to rainfall impact analysis without a spatial dimension. In this study, we developed a mixed Bayesian statistical model to evaluate the effects of climatic and ecological determinants on the spatiotemporal dynamics of the two main vectors. Adult mosquito abundance data were generated from July to December every fortnight in 2005-2006 at 79 sites, including temporary ponds, bare soils, shrubby savannah, wooded savannah, steppes, and villages in the Barkédji area. The results demonstrate the importance of environmental factors and weather conditions for predicting mosquito abundance. The rainfall and minimum temperature were positively correlated with the abundance of Cx. poicilipes, whereas the maximum temperature had negative effects. The rainfall was negatively correlated with the abundance of Ae. vexans. After combining land cover classes, weather conditions, and vector abundance, our model was used to predict the areas and periods with the highest risks of vector pressure. This information could support decision

Fluids circulation during the Miocene rifting of the Penedès half-graben, NE Iberian Peninsula

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Baqués, Vinyet; Travé, Anna; Cantarero, Irene

2013-04-01

The Penedès half-graben, located in the north-western part of the Mediterranean, is a NE-SW oriented basin generated during the Miocene rifting. This graben is bounded to the northwest by the SE-dipping Vallès-Penedès fault, which places the Mesozoic rocks in contact with the Miocene basin-fill. The basin is filled with an up to 4 km thick succession of sediments divided into three lithostratigraphic units. From base to top: (1) a lower continental complex, (2) a continental to marine complex and (3) an upper continental complex. These units are covered by Pliocene deposits which onlap a Messinian regional erosive surface. The structural features within the Penedès half-graben allow defining three deformational phases during the Miocene rifting. The first, during the syn-rift, two successive stages of NE-SW normal faults were formed. The second, during the early post-rift, one stage of NE-SW normal faults and one minor compression phase with a dextral directional developed. The third, during the late post-rift, two successive stages of N-S trending extensional fractures (faults and joints) and one minor compression with a sinistral component developed. The fractures related to the syn-rift stage acted as conduits for meteoric fluids both, in the phreatic and in the vadose zone. During the early post-rift, Fe2+- rich fluids precipitated oxides along the NE-SW fault planes. The dextral directional faults served as conduits for meteoric fluids which reequilibrated totally the marine Miocene host rocks under the phreatic environment. The late post-rift stage was characterized by marine fluids upflowing through the N-S fractures, probably derived from the Miocene marine interval, which mixed with meteoric fluids producing dolomitization. The second set of N-S fractures served as conduits for meteoric fluids characterised by δ13C-depleted soil-derived CO2 attributed to precipitation in the vadose zone. The change from phreatic to vadose meteoric environment and the

Crustal Deformation across the Jericho Valley Section of the Dead Sea Fault as Resolved by Detailed Field and Geodetic Observations

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Hamiel, Yariv; Piatibratova, Oksana; Mizrahi, Yaakov; Nahmias, Yoav; Sagy, Amir

2018-04-01

Detailed field and geodetic observations of crustal deformation across the Jericho Fault section of the Dead Sea Fault are presented. New field observations reveal several slip episodes that rupture the surface, consist with strike slip and extensional deformation along a fault zone width of about 200 m. Using dense Global Positioning System measurements, we obtain the velocities of new stations across the fault. We find that this section is locked for strike-slip motion with a locking depth of 16.6 ± 7.8 km and a slip rate of 4.8 ± 0.7 mm/year. The Global Positioning System measurements also indicate asymmetrical extension at shallow depths of the Jericho Fault section, between 0.3 and 3 km. Finally, our results suggest the vast majority of the sinistral slip along the Dead Sea Fault in southern Jorden Valley is accommodated by the Jericho Fault section.

3D crustal model of the US and Canada East Coast rifted margin

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Dowla, N.; Bird, D. E.; Murphy, M. A.

2017-12-01

We integrate seismic reflection and refraction data with gravity and magnetic data to generate a continent-scale 3D crustal model of the US and Canada East Coast, extending north from the Straits of Florida to Newfoundland, and east from the Appalachian Mountains to the Central Atlantic Ocean. The model includes five layers separated by four horizons: sea surface, topography, crystalline basement, and Moho. We tested magnetic depth-to-source techniques to improve the basement morphology, from published sources, beneath the continental Triassic rift basins and outboard to the Jurassic ocean floor. A laterally varying density grid was then produced for the resultant sedimentary rock layer thickness based on an exponential decay function that approximates sedimentary compaction. Using constant density values for the remaining layers, we calculated an isostatically compensated Moho. The following structural inversion results of the Moho, controlled by seismic refraction depths, advances our understanding of rift-to-drift crustal geometries, and provides a regional context for additional studies.

Predicting the mosquito species and vertebrate species involved in the theoretical transmission of Rift Valley fever virus in the United States.

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Andrew J Golnar

2014-09-01

Full Text Available Rift Valley fever virus (RVFV is a mosquito-borne virus in the family Bunyaviridiae that has spread throughout continental Africa to Madagascar and the Arabian Peninsula. The establishment of RVFV in North America would have serious consequences for human and animal health in addition to a significant economic impact on the livestock industry. Published and unpublished data on RVFV vector competence, vertebrate host competence, and mosquito feeding patterns from the United States were combined to quantitatively implicate mosquito vectors and vertebrate hosts that may be important to RVFV transmission in the United States. A viremia-vector competence relationship based on published mosquito transmission studies was used to calculate a vertebrate host competence index which was then combined with mosquito blood feeding patterns to approximate the vector and vertebrate amplification fraction, defined as the relative contribution of the mosquito or vertebrate host to pathogen transmission. Results implicate several Aedes spp. mosquitoes and vertebrates in the order Artiodactyla as important hosts for RVFV transmission in the U.S. Moreover, this study identifies critical gaps in knowledge which would be necessary to complete a comprehensive analysis identifying the different contributions of mosquitoes and vertebrates to potential RVFV transmission in the U.S. Future research should focus on (1 the dose-dependent relationship between viremic exposure and the subsequent infectiousness of key mosquito species, (2 evaluation of vertebrate host competence for RVFV among North American mammal species, with particular emphasis on the order Artiodactyla, and (3 identification of areas with a high risk for RVFV introduction so data on local vector and host populations can help generate geographically appropriate amplification fraction estimates.

Rift Valley fever virus NSs protein promotes post-transcriptional downregulation of protein kinase PKR and inhibits eIF2alpha phosphorylation.

Science.gov (United States)

Ikegami, Tetsuro; Narayanan, Krishna; Won, Sungyong; Kamitani, Wataru; Peters, C J; Makino, Shinji

2009-02-01

Rift Valley fever virus (RVFV) (genus Phlebovirus, family Bunyaviridae) is a negative-stranded RNA virus with a tripartite genome. RVFV is transmitted by mosquitoes and causes fever and severe hemorrhagic illness among humans, and fever and high rates of abortions in livestock. A nonstructural RVFV NSs protein inhibits the transcription of host mRNAs, including interferon-beta mRNA, and is a major virulence factor. The present study explored a novel function of the RVFV NSs protein by testing the replication of RVFV lacking the NSs gene in the presence of actinomycin D (ActD) or alpha-amanitin, both of which served as a surrogate of the host mRNA synthesis suppression function of the NSs. In the presence of the host-transcriptional inhibitors, the replication of RVFV lacking the NSs protein, but not that carrying NSs, induced double-stranded RNA-dependent protein kinase (PKR)-mediated eukaryotic initiation factor (eIF)2alpha phosphorylation, leading to the suppression of host and viral protein translation. RVFV NSs promoted post-transcriptional downregulation of PKR early in the course of the infection and suppressed the phosphorylated eIF2alpha accumulation. These data suggested that a combination of RVFV replication and NSs-induced host transcriptional suppression induces PKR-mediated eIF2alpha phosphorylation, while the NSs facilitates efficient viral translation by downregulating PKR and inhibiting PKR-mediated eIF2alpha phosphorylation. Thus, the two distinct functions of the NSs, i.e., the suppression of host transcription, including that of type I interferon mRNAs, and the downregulation of PKR, work together to prevent host innate antiviral functions, allowing efficient replication and survival of RVFV in infected mammalian hosts.

Predicting the mosquito species and vertebrate species involved in the theoretical transmission of Rift Valley fever virus in the United States.

Science.gov (United States)

Golnar, Andrew J; Turell, Michael J; LaBeaud, A Desiree; Kading, Rebekah C; Hamer, Gabriel L

2014-09-01

Rift Valley fever virus (RVFV) is a mosquito-borne virus in the family Bunyaviridiae that has spread throughout continental Africa to Madagascar and the Arabian Peninsula. The establishment of RVFV in North America would have serious consequences for human and animal health in addition to a significant economic impact on the livestock industry. Published and unpublished data on RVFV vector competence, vertebrate host competence, and mosquito feeding patterns from the United States were combined to quantitatively implicate mosquito vectors and vertebrate hosts that may be important to RVFV transmission in the United States. A viremia-vector competence relationship based on published mosquito transmission studies was used to calculate a vertebrate host competence index which was then combined with mosquito blood feeding patterns to approximate the vector and vertebrate amplification fraction, defined as the relative contribution of the mosquito or vertebrate host to pathogen transmission. Results implicate several Aedes spp. mosquitoes and vertebrates in the order Artiodactyla as important hosts for RVFV transmission in the U.S. Moreover, this study identifies critical gaps in knowledge which would be necessary to complete a comprehensive analysis identifying the different contributions of mosquitoes and vertebrates to potential RVFV transmission in the U.S. Future research should focus on (1) the dose-dependent relationship between viremic exposure and the subsequent infectiousness of key mosquito species, (2) evaluation of vertebrate host competence for RVFV among North American mammal species, with particular emphasis on the order Artiodactyla, and (3) identification of areas with a high risk for RVFV introduction so data on local vector and host populations can help generate geographically appropriate amplification fraction estimates.

Integrated Analysis of Environment, Cattle and Human Serological Data: Risks and Mechanisms of Transmission of Rift Valley Fever in Madagascar.

Science.gov (United States)

Olive, Marie-Marie; Chevalier, Véronique; Grosbois, Vladimir; Tran, Annelise; Andriamandimby, Soa-Fy; Durand, Benoit; Ravalohery, Jean-Pierre; Andriamamonjy, Seta; Rakotomanana, Fanjasoa; Rogier, Christophe; Heraud, Jean-Michel

2016-07-01

Rift Valley fever (RVF) is a vector-borne disease affecting ruminants and humans. Madagascar was heavily affected by RVF in 2008-2009, with evidence of a large and heterogeneous spread of the disease. The identification of at-risk environments is essential to optimize the available resources by targeting RVF surveillance in Madagascar. Herein, the objectives of our study were: (i) to identify the environmental factors and areas favorable to RVF transmission to both cattle and human and (ii) to identify human behaviors favoring human infections in Malagasy contexts. First, we characterized the environments of Malagasy communes using a Multiple Factor Analysis (MFA). Then, we analyzed cattle and human serological data collected at national level using Generalized Linear Mixed Models, with the individual serological status (cattle or human) as the response, and MFA factors, as well as other potential risk factors (cattle density, human behavior) as explanatory variables. Cattle and human seroprevalence rates were positively associated to humid environments (p<0.001). Areas with high cattle density were at risk (p<0.01; OR = 2.6). Furthermore, our analysis showed that frequent contact with raw milk contributed to explain human infection (OR = 1.6). Finally, our study highlighted the eastern-coast, western and north-western parts as high-risk areas for RVF transmission in cattle. Our integrated approach analyzing environmental, cattle and human datasets allow us to bring new insight on RVF transmission patterns in Madagascar. The association between cattle seroprevalence, humid environments and high cattle density suggests that concomitant vectorial and direct transmissions are critical to maintain RVF enzootic transmission. Additionally, in the at-risk humid environment of the western, north-western and the eastern-coast areas, suitable to Culex and Anopheles mosquitoes, vectorial transmission probably occurs in both cattle and human. The relative contribution of

Characterising and comparing drug-dispensing practices at animal health outlets in the Rift Valley, Kenya: an exploratory analysis (part II).

Science.gov (United States)

Higham, L E; Ongeri, W; Asena, K; Thrusfield, M V

2016-12-01

A mixed-method study was conducted in the Rift Valley of Kenya to characterise drug-dispensing practices amongst staff at animal health outlets and to explore perceptions of veterinary medicines amongst pastoralists and farmers. Forty structured questionnaires were administered to staff at animal health outlets, including franchise outlets of 'Sidai Africa Ltd.', and two focus group discussions were facilitated to explore the perceptions of local animal health services by a Maasai pastoralist group and a dairy farmer cooperative. Differences were detected in the characteristics of Sidai outlets, agrovets, pharmacies and dukas. A greater proportion of Sidai outlet staff selected drugs based on principles of responsible drug use than staff at other types of outlet, and technical qualifications and training were associated with responsible drug use. Across all outlet types, staff knowledge and training gaps were identified, including in the correct administration of medicines. The majority of drug sales are accompanied by verbal advice to farmers. Members of the Maasai pastoralist group were concerned about accidental self-medication, withdrawal periods, drug residues and the misuse of drugs due to a lack of quality information and advice. The dairy farmer group raised similar concerns, reporting under-dosing as a common mistake amongst farmers. This study concludes that current knowledge, attitudes and practices of many service providers and livestock owners in the sale, purchase and use of veterinary medicines present risks of drug misuse and therefore the emergence of antimicrobial resistance. There is a clear demand from livestock keepers for accessible, affordable and quality animal health services and products in Kenya, and animal health practitioners have the potential to provide increased support to livestock-based livelihoods and act as stewards of our existing portfolio of animal and human medicines.

Integrated Analysis of Environment, Cattle and Human Serological Data: Risks and Mechanisms of Transmission of Rift Valley Fever in Madagascar.

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Marie-Marie Olive

2016-07-01

Full Text Available Rift Valley fever (RVF is a vector-borne disease affecting ruminants and humans. Madagascar was heavily affected by RVF in 2008-2009, with evidence of a large and heterogeneous spread of the disease. The identification of at-risk environments is essential to optimize the available resources by targeting RVF surveillance in Madagascar. Herein, the objectives of our study were: (i to identify the environmental factors and areas favorable to RVF transmission to both cattle and human and (ii to identify human behaviors favoring human infections in Malagasy contexts.First, we characterized the environments of Malagasy communes using a Multiple Factor Analysis (MFA. Then, we analyzed cattle and human serological data collected at national level using Generalized Linear Mixed Models, with the individual serological status (cattle or human as the response, and MFA factors, as well as other potential risk factors (cattle density, human behavior as explanatory variables. Cattle and human seroprevalence rates were positively associated to humid environments (p<0.001. Areas with high cattle density were at risk (p<0.01; OR = 2.6. Furthermore, our analysis showed that frequent contact with raw milk contributed to explain human infection (OR = 1.6. Finally, our study highlighted the eastern-coast, western and north-western parts as high-risk areas for RVF transmission in cattle.Our integrated approach analyzing environmental, cattle and human datasets allow us to bring new insight on RVF transmission patterns in Madagascar. The association between cattle seroprevalence, humid environments and high cattle density suggests that concomitant vectorial and direct transmissions are critical to maintain RVF enzootic transmission. Additionally, in the at-risk humid environment of the western, north-western and the eastern-coast areas, suitable to Culex and Anopheles mosquitoes, vectorial transmission probably occurs in both cattle and human. The relative contribution

Commercial production of ethanol in the San Luis Valley, Colorado. Final report

Energy Technology Data Exchange (ETDEWEB)

Hewlett, E.M.; Erickson, M.V.; Ferguson, C.D.; Boswell, B.S.; Walter, K.M.; Hart, M.L.; Sherwood, P.B.

1983-07-01

The commercial feasibility of producing between 76 and 189 million liters (20 to 50 million gallons) of ethanol annually in the San Luis Valley, Colorado using geothermal energy as the primary heat source was assessed. The San Luis Valley is located in south-central Colorado. The valley is a high basin situated approximately 2316 meters (7600 feet) above sea level which contains numerous warm water wells and springs. A known geothermal resource area (IGRA) is located in the east-central area of the valley. The main industry in the valley is agriculture, while the main industry in the surrounding mountains is lumber. Both of these industries can provide feedstocks for the production of ethanol.

The Jurassic of Denmark and Greenland: The Jurassic of East Greenland: a sedimentary record of thermal subsidence, onset and culmination of rifting

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Surlyk, Finn

2003-10-01

Full Text Available The Late Palaeozoic – Mesozoic extensional basin complex of East Greenland contains a record of deposition during a period of Rhaetian – Early Bajocian thermal subsidence, the onset of riftingin the Late Bajocian, its growth during the Bathonian–Kimmeridgian, culmination of rifting in the Volgian – Early Ryazanian, and waning in the Late Ryazanian – Hauterivian. The area was centred over a palaeolatitude of about 45°N in the Rhaetian and drifted northwards to about 50°N in the Hauterivian. A major climate change from arid to humid subtropical conditions took place at the Norian–Rhaetian transition. Deposition was in addition governed by a long-term sea-level rise with highstands in the Toarcian–Aalenian, latest Callovian and Kimmeridgian, and lowstands in the latest Bajocian – earliest Bathonian, Middle Oxfordian and Volgian.The Rhaetian – Lower Bajocian succession is considered the upper part of a megasequence, termed J1, with its base in the upper Lower Triassic, whereas the Upper Bajocian – Hauterivian succession forms a complete, syn-rift megasequence, termed J2. The southern part of the basin complex in Jameson Land contains a relatively complete Rhaetian–Ryazanian succession and underwent only minor tilting during Middle Jurassic – earliest Cretaceous rifting. Rhaetian – Lower Jurassic deposits are absent north of Jameson Land and this region was fragmented into strongly tilted fault blocks during the protracted rift event. The syn-rift successions of the two areas accordingly show different long-term trends in sedimentary facies. In the southern area, the J2 syn-rift megasequence forms a symmetrical regressive–transgressive–regressive cycle, whereas the J2 megasequence in the northern area shows an asymmetrical, stepwise deepening trend.A total of eight tectonostratigraphic sequences are recognised in the Rhaetian–Hauterivian interval. They reflect major changes in basin configuration, drainage systems

Chronology and volcanology of the 1949 multi-vent rift-zone eruption on La Palma (Canary Islands)

Science.gov (United States)

Klügel, A.; Schmincke, H.-U.; White, J. D. L.; Hoernle, K. A.

1999-12-01

The compositionally zoned San Juan eruption on La Palma emanated from three eruptive centers located along a north-south-trending rift zone in the south of the island. Seismic precursors began weakly in 1936 and became strong in March 1949, with their foci progressing from the north of the rift zone towards its south. This suggests that magma ascended beneath the old Taburiente shield volcano and moved southward along the rift. The eruption began on June 24, 1949, with phreatomagmatic activity at Duraznero crater on the ridgetop (ca. 1880 m above sea level), where five vents erupted tephritic lava along a 400-m-long fissure. On June 8, the Duraznero vents shut down abruptly, and the activity shifted to an off-rift fissure at Llano del Banco, located at ca. 550 m lower elevation and 3 km to the northwest. This eruptive center issued initially tephritic aa and later basanitic pahoehoe lava at high rates, producing a lava flow that entered the sea. Two days after basanite began to erupt at Llano del Banco, Hoyo Negro crater (ca. 1880 m asl), located 700 m north of Duraznero along the rift, opened on July 12 and produced ash and bombs of basanitic to phonotephritic composition in violent phreatomagmatic explosions ( White and Schmincke, 1999). Llano del Banco and Hoyo Negro were simultaneously active for 11 days and showed a co-variance of their eruption rates indicating a shallow hydraulic connection. On July 30, after 3 days of quiescence at all vents, Duraznero and Hoyo Negro became active again during a final eruptive phase. Duraznero issued basanitic lava at high rates for 12 h and produced a lava flow that descended towards the east coast. The lava contains ca. 1 vol.% crustal and mantle xenoliths consisting of 40% tholeiitic gabbros from the oceanic crust, 35% alkaline gabbros, and 20% ultramafic cumulates. The occurrence of xenoliths almost exclusively in the final lava is consistent with their origin by wall-rock collapse at depth near the end of the eruption

Surface deformation in volcanic rift zones

Science.gov (United States)

Pollard, D.D.; Delaney, P.T.; Duffield, W.A.; Endo, E.T.; Okamura, A.T.

1983-01-01

The principal conduits for magma transport within rift zones of basaltic volcanoes are steeply dipping dikes, some of which feed fissure eruptions. Elastic displacements accompanying a single dike emplacement elevate the flanks of the rift relative to a central depression. Concomitant normal faulting may transform the depression into a graben thus accentuating the topographic features of the rift. If eruption occurs the characteristic ridge-trough-ridge displacement profile changes to a single ridge, centered at the fissure, and the erupted lava alters the local topography. A well-developed rift zone owes its structure and topography to the integrated effects of many magmatic rifting events. To investigate this process we compute the elastic displacements and stresses in a homogeneous, two-dimensional half-space driven by a pressurized crack that may breach the surface. A derivative graphical method permits one to estimate the three geometric parameters of the dike (height, inclination, and depth-to-center) and the mechanical parameter (driving pressure/rock stiffness) from a smoothly varying displacement profile. Direct comparison of measured and theoretical profiles may be used to estimate these parameters even if inelastic deformation, notably normal faulting, creates discontinuities in the profile. Geological structures (open cracks, normal faults, buckles, and thrust faults) form because of stresses induced by dike emplacement and fissure eruption. Theoretical stress states associated with dilation of a pressurized crack are used to interpret the distribution and orientation of these structures and their role in rift formation. ?? 1983.

Evidence for cross rift structural controls on deformation and seismicity at a continental rift caldera

Science.gov (United States)

Lloyd, Ryan; Biggs, Juliet; Wilks, Matthew; Nowacki, Andy; Kendall, J.-Michael; Ayele, Atalay; Lewi, Elias; Eysteinsson, Hjálmar

2018-04-01

In continental rifts structural heterogeneities, such as pre-existing faults and foliations, are thought to influence shallow crustal processes, particularly the formation of rift faults, magma reservoirs and surface volcanism. We focus on the Corbetti caldera, in the southern central Main Ethiopian Rift. We measure the surface deformation between 22nd June 2007 and 25th March 2009 using ALOS and ENVISAT SAR interferograms and observe a semi-circular pattern of deformation bounded by a sharp linear feature cross-cutting the caldera, coincident with the caldera long axis. The signal reverses in sign but is not seasonal: from June to December 2007 the region south of this structure moves upwards 3 cm relative to the north, while from December 2007 until November 2008 it subsides by 2 cm. Comparison of data taken from two different satellite look directions show that the displacement is primarily vertical. We discuss potential mechanisms and conclude that this deformation is associated with pressure changes within a shallow (statistically consistent with this fault structure, indicating that the fault has also controlled the migration of magma from a reservoir to the surface over tens of thousands of years. Spatial patterns of seismicity are consistent with a cross-rift structure that extents outside the caldera and to a depth of ∼30 km, and patterns of seismic anisotropy suggests stress partitioning occurs across the structure. We discuss the possible nature of this structure, and conclude that it is most likely associated with the Goba-Bonga lineament, which cross-cuts and pre-dates the current rift. Our observations show that pre-rift structures play an important role in magma transport and shallow hydrothermal processes, and therefore they should not be neglected when discussing these processes.

Rift propagation at craton margin.: Distribution of faulting and volcanism in the North Tanzanian Divergence (East Africa) during Neogene times

Science.gov (United States)

Le Gall, B.; Nonnotte, P.; Rolet, J.; Benoit, M.; Guillou, H.; Mousseau-Nonnotte, M.; Albaric, J.; Deverchère, J.

2008-02-01

A revised kinematic model is proposed for the Neogene tectono-magmatic development of the North Tanzanian Divergence where the axial valley in S Kenya splits southwards into a wide diverging pattern of block faulting in association with the disappearance of volcanism. Propagation of rifting along the S Kenya proto-rift during the last 8 Ma is first assumed to have operated by linkage of discrete magmatic cells as far S as the Ngorongoro-Kilimanjaro transverse volcanic belt that follows the margin of cratonic blocks in N Tanzania. Strain is believed to have nucleated throughout the thermally-weakened lithosphere in the transverse volcanic belt that might have later linked the S Kenya and N Tanzania rift segments with marked structural changes along-strike. The North Tanzanian Divergence is now regarded as a two-armed rift pattern involving: (1) a wide domain of tilted fault blocks to the W (Mbulu) that encompasses the Eyasi and Manyara fault systems, in direct continuation with the Natron northern trough. The reactivation of basement fabrics in the cold and intact Precambrian lithosphere in the Mbulu domain resulted in an oblique rift pattern that contrasts with the orthogonal extension that prevailed in the Magadi-Natron trough above a more attenuated lithosphere. (2) To the E, the Pangani horst-like range is thought to be a younger (< 1 Ma) structure that formed in response to the relocation of extension S of the Kilimanjaro magmatic center. A significant contrast in the mechanical behaviour of the stretched lithosphere in the North Tanzanian diverging rift is assumed to have occurred on both sides of the Masai cratonic block with a mid-crustal decoupling level to the W where asymmetrical fault-basin patterns are dominant (Magadi-Natron and Mbulu), whereas a component of dynamical uplift is suspected to have caused the topographic elevation of the Pangani range in relation with possible far-travelled mantle melts produced at depth further N.

Geomorphic Response to Spatial and Temporal Tectonic uplift on the Kenya Rift of East African Rift System

Science.gov (United States)

Xue, L.; Abdelsalam, M. G.

2017-12-01

Tectonic uplifts of the shoulders of the East Africa Rift System (EARS) have significant impact on the geological record by reorganizing drainage systems, increasing sediment supply, and changing climate and biogeography. Recent studies in geochronology, geomorphology and geophysics have provided some understanding of the timing of tectonic uplift and its distribution pattern of the (EARS). We do not know how the vertical motion is localized along the rift axis and the relative roles of upwelling of magma and rift extensional processes play in tectonic uplift history. This work presents detailed morphometric study of the fluvial landscape response to the tectonic uplift and climate shifting of the Kenya Rift shoulders in order to reconstruct their incision history, with special attention to timing, location, and intensity of uplift episodes. This work compiles the Shuttle Radar Topography Mission (SRTM) Digital Elevation Model (DEM) and Sentinel-2A data, summarized previous 39Ar-40Ar and thermochronology data, and calculates long-term incision rate and geomorphic proxies (normalized steepness and chi-integral) along the Kenya Rift. It also models the age of tectonic/climatic events by using knickpoint celerity model and R/SR integrative approach. It found that the maximum long-term incision rates of 300 mm/kyr to be at the central Kenya Rift, possibly related to the mantle-driven process and rapid tectonic uplift. The geomorphic proxies indicate southward decreasing pattern of the short-term incision rate, possibly related to the migration of the mantle plume.

A ΩXaV motif in the Rift Valley fever virus NSs protein is essential for degrading p62, forming nuclear filaments and virulence.

Science.gov (United States)

Cyr, Normand; de la Fuente, Cynthia; Lecoq, Lauriane; Guendel, Irene; Chabot, Philippe R; Kehn-Hall, Kylene; Omichinski, James G

2015-05-12

Rift Valley fever virus (RVFV) is a single-stranded RNA virus capable of inducing fatal hemorrhagic fever in humans. A key component of RVFV virulence is its ability to form nuclear filaments through interactions between the viral nonstructural protein NSs and the host general transcription factor TFIIH. Here, we identify an interaction between a ΩXaV motif in NSs and the p62 subunit of TFIIH. This motif in NSs is similar to ΩXaV motifs found in nucleotide excision repair (NER) factors and transcription factors known to interact with p62. Structural and biophysical studies demonstrate that NSs binds to p62 in a similar manner as these other factors. Functional studies in RVFV-infected cells show that the ΩXaV motif is required for both nuclear filament formation and degradation of p62. Consistent with the fact that the RVFV can be distinguished from other Bunyaviridae-family viruses due to its ability to form nuclear filaments in infected cells, the motif is absent in the NSs proteins of other Bunyaviridae-family viruses. Taken together, our studies demonstrate that p62 binding to NSs through the ΩXaV motif is essential for degrading p62, forming nuclear filaments and enhancing RVFV virulence. In addition, these results show how the RVFV incorporates a simple motif into the NSs protein that enables it to functionally mimic host cell proteins that bind the p62 subunit of TFIIH.

Rifting in heterogeneous lithosphere inferences from numerical modeling of the northern North Sea and the Oslo Graben.

NARCIS (Netherlands)

Pascal Candas, C.; Cloetingh, S.A.P.L.

2002-01-01

Permian rifting and magmatism are widely documented across NW Europe. The different Permian basins often display contrasting structural styles and evolved in lithospheric domains with contrasting past evolution and contrasting thermotectonic ages. In particular, the Oslo Graben and the northern

Polyphase Rifting and Breakup of the Central Mozambique Margin

Science.gov (United States)

Senkans, Andrew; Leroy, Sylvie; d'Acremont, Elia; Castilla, Raymi

2017-04-01

The breakup of the Gondwana supercontinent resulted in the formation of the Central Mozambique passive margin as Africa and Antarctica were separated during the mid-Jurassic period. The identification of magnetic anomalies in the Mozambique Basin and Riiser Larsen Sea means that post-oceanisation plate kinematics are well-constrained. Unresolved questions remain, however, regarding the initial fit, continental breakup process, and the first relative movements of Africa and Antarctica. This study uses high quality multi-channel seismic reflection profiles in an effort to identify the major crustal domains in the Angoche and Beira regions of the Central Mozambique margin. This work is part of the integrated pluri-disciplinary PAMELA project*. Our results show that the Central Mozambique passive margin is characterised by intense but localised magmatic activity, evidenced by the existence of seaward dipping reflectors (SDR) in the Angoche region, as well as magmatic sills and volcanoclastic material which mark the Beira High. The Angoche region is defined by a faulted upper-continental crust, with the possible exhumation of lower crustal material forming an extended ocean-continent transition (OCT). The profiles studied across the Beira high reveal an offshore continental fragment, which is overlain by a pre-rift sedimentary unit likely to belong to the Karoo Group. Faulting of the crust and overlying sedimentary unit reveals that the Beira High has recorded several phases of deformation. The combination of our seismic interpretation with existing geophysical and geological results have allowed us to propose a breakup model which supports the idea that the Central Mozambique margin was affected by polyphase rifting. The analysis of both along-dip and along-strike profiles shows that the Beira High initially experienced extension in a direction approximately parallel to the Mozambique coastline onshore of the Beira High. Our results suggest that the Beira High results

Commercial production of ethanol in the San Luis Valley, Colorado. Final Report

Energy Technology Data Exchange (ETDEWEB)

Hewlett, E.M.; Erickson, M.V.; Ferguson, C.D.; Sherwood, P.B.; Boswell, B.S.; Walter, K.M.; Hart, M.L.

1983-07-01

The purpose of this study is to assess the commercial feasibility of producing between 76 and 189 million liters (20 and 50 million gallons) of ethanol annually in the San Luis Valley, Colorado using geothermal energy as the primary heat source. The San Luis Valley is located in south-central Colorado. The valley is a high basin situated approximately 2316 meters (7600 feet) above sea level which contains numerous warm water wells and springs. A known geothermal resource area (KGRA) is located in the east-central area of the valley. The main industry in the valley is agriculture, while the main industry in the surrounding mountains is lumber. Both of these industries can provide feedstock for the production of ethanol.

Long wavelength magnetic anomalies over continental rifts in cratonic region

Science.gov (United States)

Friedman, S. A.; Persaud, P.; Ferre, E. C.; Martín-Hernández, F.; Feinberg, J. M.

2017-12-01

New collections of unaltered mantle xenoliths shed light on potential upper mantle contributions to long wavelength magnetic anomalies (LWMA) in continental rifts in cratonic / shield areas. The new material originates from the East African Rift (Tanzania), the Rio Grande Rift (U.S.A.), the Rhine Rift (Germany), and the West Antarctic Rift (Antarctica). The xenoliths sample the uppermost ( 0.2 or Fe geotherms (>60ºC/km) that are characteristic of rifted regions preclude any contribution to LWMA at depths >10 km. Hence, only upper basalts and hypovolcanic mafic sills would constitute potential magnetic sources. In contrast, the margins of these rifted regions consist of refractory cratonic domains, often characterized by oxidized sublithospheric mantle that host significant concentrations of primary magnetite. The higher NRMs of these peridotites (up to 15 A/m, Qn > 2.5) combined with much lower geotherms (as low as 15ºC/km) allows for a 5 to 10 km layer of uppermost mantle to potentially contribute to LWMA. Assuming that Qn values in rift margins are also gradient across the rift would primarily reflect thermal equilibration over time.

75 FR 59285 - Sonny Bono Salton Sea National Wildlife Refuge Complex (Sonny Bono Salton Sea National Wildlife...

Science.gov (United States)

2010-09-27

... DEPARTMENT OF THE INTERIOR Fish and Wildlife Service [FWS-R8-R-2010-N169; 80230-1265-0000-S3] Sonny Bono Salton Sea National Wildlife Refuge Complex (Sonny Bono Salton Sea National Wildlife Refuge and Coachella Valley National Wildlife Refuge), Imperial and Riverside Counties, CA Correction Notice...

Syn-rift unconformities punctuating the lower-middle Cambrian transition in the Atlas Rift, Morocco

OpenAIRE

Álvaro, J. Javier; Ezzouhairi, Hassan; Clausen, Sébastien; Ribeiro, Maria Luísa; Solá, Ana Rita

2015-01-01

The Cambrian Tamdroust and Bab n’Ali Volcanic Complexes represent two magmatic episodes developed in the latest Ediacaran–Cambrian Atlas Rift of Morocco. Their rifting pulses were accompanied by accumulation of volcanosedimentary edifices (dominated by effusive lava flows in the former and explosive acidic aprons in the latter) associated with active tilting and uplift. Sealing of their peneplaned horst-and-graben palaeotopographies led to the onset of distinct onlapping geometrie...

Crustal structure and development of the SW Barents Sea and the adjacent continental margin

Energy Technology Data Exchange (ETDEWEB)

Breivik, Asbjoern Johan

1998-12-31

Because of its expected petroleum potential, the western Barents Sea has been extensively mapped and investigated. The present thesis deals with many aspects of the geological development of this area. The emphasis is on Late Paleozoic structuring, Late Mesozoic basin formation, and early Tertiary margin formation including geodynamical response to the late Cenozoic sedimentation. The thesis begins with a review of the literature on the Late Palaeozoic structural development of the south-western Barents Sea, Svalbard and eastern Greenland. A structural map is developed for the Upper Carboniferous rift system in the southwestern Barents Sea that shows the interference of the northeasterly and the northerly structural grain. A discussion of the Ottar Basin uses a combination of seismic interpretation and gravity modelling to investigate this important structural element of the Upper Palaeozoic rift system. Previous work on Late Mesozoic basin formation in the southwestern Barents Sea is extended by incorporating new seismic reflection data and gravity modelling. Finally, the focus is shifted from the Barents Sea shelf to the continental-ocean transition and the oceanic basin. Gridded free-air gravity data from the ERS-1 enables the construction of a Bouguer gravity map of unprecedented resolution. The relationship between isostacy and gravity was resolved by modelling the thermal structure across the margin. Admittance analysis of the relationship between bathymetry and free-air gravity indicates an elastic thickness of the oceanic Lithosphere of 15-20 km, which is compatible with the depth to the 450{sup o}C isotherm obtained from thermal modelling. It is concluded that the southwestern Barents Sea margin does not deviate in any significant respects from passive rifted margins, except for a very straight and narrow continent-ocean transition zone. 332 refs., 55 figs., 7 tabs.

Dykes and structures of the NE rift of Tenerife, Canary Islands: a record of stabilisation and destabilisation of ocean island rift zones

Science.gov (United States)

Delcamp, A.; Troll, V. R.; van Wyk de Vries, B.; Carracedo, J. C.; Petronis, M. S.; Pérez-Torrado, F. J.; Deegan, F. M.

2012-07-01

Many oceanic island rift zones are associated with lateral sector collapses, and several models have been proposed to explain this link. The North-East Rift Zone (NERZ) of Tenerife Island, Spain offers an opportunity to explore this relationship, as three successive collapses are located on both sides of the rift. We have carried out a systematic and detailed mapping campaign on the rift zone, including analysis of about 400 dykes. We recorded dyke morphology, thickness, composition, internal textural features and orientation to provide a catalogue of the characteristics of rift zone dykes. Dykes were intruded along the rift, but also radiate from several nodes along the rift and form en échelon sets along the walls of collapse scars. A striking characteristic of the dykes along the collapse scars is that they dip away from rift or embayment axes and are oblique to the collapse walls. This dyke pattern is consistent with the lateral spreading of the sectors long before the collapse events. The slump sides would create the necessary strike-slip movement to promote en échelon dyke patterns. The spreading flank would probably involve a basal decollement. Lateral flank spreading could have been generated by the intense intrusive activity along the rift but sectorial spreading in turn focused intrusive activity and allowed the development of deep intra-volcanic intrusive complexes. With continued magma supply, spreading caused temporary stabilisation of the rift by reducing slopes and relaxing stress. However, as magmatic intrusion persisted, a critical point was reached, beyond which further intrusion led to large-scale flank failure and sector collapse. During the early stages of growth, the rift could have been influenced by regional stress/strain fields and by pre-existing oceanic structures, but its later and mature development probably depended largely on the local volcanic and magmatic stress/strain fields that are effectively controlled by the rift zone growth

The role of inheritance in structuring hyperextended rift systems

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Manatschal, Gianreto; Lavier, Luc; Chenin, Pauline

2015-04-01

A long-standing question in Earth Sciences is related to the importance of inheritance in controlling tectonic processes. In contrast to physical processes that are generally applicable, assessing the role of inheritance suffers from two major problems: firstly, it is difficult to appraise without having insights into the history of a geological system; and secondly all inherited features are not reactivated during subsequent deformation phases. Therefore, the aim of our presentation is to give some conceptual framework about how inheritance may control the architecture and evolution of hyperextended rift systems. We use the term inheritance to refer to the difference between an "ideal" layer-cake type lithosphere and a "real" lithosphere containing heterogeneities and we define 3 types of inheritance, namely structural, compositional and thermal inheritance. Moreover, we assume that the evolution of hyperextended rift systems reflects the interplay between their inheritance (innate/"genetic code") and the physical processes at play (acquired/external factors). Thus, by observing the architecture and evolution of hyperextended rift systems and integrating the physical processes, one my get hints on what may have been the original inheritance of a system. Using this approach, we focus on 3 well-studied rift systems that are the Alpine Tethys, Pyrenean-Bay of Biscay and Iberia-Newfoundland rift systems. For the studied examples we can show that: 1) strain localization on a local scale and during early stages of rifting is controlled by inherited structures and weaknesses 2) the architecture of the necking zone seems to be influenced by the distribution and importance of ductile layers during decoupled deformation and is consequently controlled by the thermal structure and/or the inherited composition of the curst 3) the location of breakup in the 3 examples is not significantly controlled by the inherited structures 4) inherited mantle composition and rift

Crustal structure of the rifted volcanic margins and uplifted plateau of Western Yemen from receiver function analysis

Science.gov (United States)

Ahmed, Abdulhakim; Tiberi, Christel; Leroy, Sylvie; Stuart, Graham W.; Keir, Derek; Sholan, Jamal; Khanbari, Khaled; Al-Ganad, Ismael; Basuyau, Clémence

2013-06-01

We analyse P-wave receiver functions across the western Gulf of Aden and southern Red Sea continental margins in Western Yemen to constrain crustal thickness, internal crustal structure and the bulk seismic velocity characteristics in order to address the role of magmatism, faulting and mechanical crustal thinning during continental breakup. We analyse teleseismic data from 21 stations forming the temporary Young Conjugate Margins Laboratory (YOCMAL) network together with GFZ and Yemeni permanent stations. Analysis of computed receiver functions shows that (1) the thickness of unextended crust on the Yemen plateau is ˜35 km; (2) this thins to ˜22 km in coastal areas and reaches less than 14 km on the Red Sea coast, where presence of a high-velocity lower crust is evident. The average Vp/Vs ratio for the western Yemen Plateau is 1.79, increasing to ˜1.92 near the Red Sea coast and decreasing to 1.68 for those stations located on or near the granitic rocks. Thinning of the crust, and by inference extension, occurs over a ˜130-km-wide transition zone from the Red Sea and Gulf of Aden coasts to the edges of the Yemen plateau. Thinning of continental crust is particularly localized in a <30-km-wide zone near the coastline, spatially co-incident with addition of magmatic underplate to the lower crust, above which on the surface we observe the presence of seaward dipping reflectors (SDRs) and thickened Oligo-Miocene syn-rift basaltic flows. Our results strongly suggest the presence of high-velocity mafic intrusions in the lower crust, which are likely either synrift magmatic intrusion into continental lower crust or alternatively depleted upper mantle underplated to the base of the crust during the eruption of the SDRs. Our results also point towards a regional breakup history in which the onset of rifting was synchronous along the western Gulf of Aden and southern Red Sea volcanic margins followed by a second phase of extension along the Red Sea margin.

Comparison of sampling techniques for Rift Valley Fever virus potential vectors, Aedes aegypti and Culex pipiens complex, in Ngorongoro District in northern Tanzania.

Science.gov (United States)

Mweya, Clement N; Kimera, Sharadhuli I; Karimuribo, Esron D; Mboera, Leonard E G

2013-07-01

We investigated mosquito sampling techniques with two types of traps and attractants at different time for trapping potential vectors for Rift Valley Fever virus. The study was conducted in six villages in Ngorongoro district in Tanzania from September to October 2012. A total of 1814 mosquitoes were collected, of which 738 were collected by CDC light traps and 1076 by Mosquito Magnet trapping technique. Of the collected mosquitoes, 12.46% (N = 226) were Aedes aegypti and 87.54% (N = 1588) were Culex pipiens complex. More mosquitoes were collected outdoors using Mosquito Magnets baited with octenol attractant, 36.38% (N =660) followed by indoor trapping using CDC light traps without attractant, 29.60% (N = 537). Most of Ae. aegypti mosquitoes were collected outdoor using Mosquito Magnets, 95% (N = 214) whereas Cx. pipiens complex were trapped both indoor using CDC light traps without attractant and outdoors using both CDC light traps baited with carbon dioxide (CO2) sachets and Mosquito Magnets. Analysis on the differences in abundance of mosquitoes trapped by different techniques using Generalized Linear Models was statistically significance at p-value < 0.05 for both species. Three hours mosquito collections show differing patterns in activity, most Ae. aegypti species were collected primarily during the first and last quarters of the day. Cx pipiens complex was active throughout the night, early evening and early morning then decreased markedly during the day time. The results presented in this paper emphasize the possibility of using Mosquito Magnets in order to efficiently capture these potential RVF vectors.

Mechanistic Insight into the Host Transcription Inhibition Function of Rift Valley Fever Virus NSs and Its Importance in Virulence.

Science.gov (United States)

Terasaki, Kaori; Ramirez, Sydney I; Makino, Shinji

2016-10-01

Rift Valley fever virus (RVFV), a member of the genus Phlebovirus within the family Bunyaviridae, causes periodic outbreaks in livestocks and humans in countries of the African continent and Middle East. RVFV NSs protein, a nonstructural protein, is a major virulence factor that exhibits several important biological properties. These include suppression of general transcription, inhibition of IFN-β promoter induction and degradation of double-stranded RNA-dependent protein kinase R. Although each of these biological functions of NSs are considered important for countering the antiviral response in the host, the individual contributions of these functions towards RVFV virulence remains unclear. To examine this, we generated two RVFV MP-12 strain-derived mutant viruses. Each carried mutations in NSs that specifically targeted its general transcription inhibition function without affecting its ability to degrade PKR and inhibit IFN-β promoter induction, through its interaction with Sin3-associated protein 30, a part of the repressor complex at the IFN-β promoter. Using these mutant viruses, we have dissected the transcription inhibition function of NSs and examined its importance in RVFV virulence. Both NSs mutant viruses exhibited a differentially impaired ability to inhibit host transcription when compared with MP-12. It has been reported that NSs suppresses general transcription by interfering with the formation of the transcription factor IIH complex, through the degradation of the p62 subunit and sequestration of the p44 subunit. Our study results lead us to suggest that the ability of NSs to induce p62 degradation is the major contributor to its general transcription inhibition property, whereas its interaction with p44 may not play a significant role in this function. Importantly, RVFV MP-12-NSs mutant viruses with an impaired general transcription inhibition function showed a reduced cytotoxicity in cell culture and attenuated virulence in young mice

Rift Valley fever virus NSs protein promotes post-transcriptional downregulation of protein kinase PKR and inhibits eIF2alpha phosphorylation.

Directory of Open Access Journals (Sweden)

Tetsuro Ikegami

2009-02-01

Full Text Available Rift Valley fever virus (RVFV (genus Phlebovirus, family Bunyaviridae is a negative-stranded RNA virus with a tripartite genome. RVFV is transmitted by mosquitoes and causes fever and severe hemorrhagic illness among humans, and fever and high rates of abortions in livestock. A nonstructural RVFV NSs protein inhibits the transcription of host mRNAs, including interferon-beta mRNA, and is a major virulence factor. The present study explored a novel function of the RVFV NSs protein by testing the replication of RVFV lacking the NSs gene in the presence of actinomycin D (ActD or alpha-amanitin, both of which served as a surrogate of the host mRNA synthesis suppression function of the NSs. In the presence of the host-transcriptional inhibitors, the replication of RVFV lacking the NSs protein, but not that carrying NSs, induced double-stranded RNA-dependent protein kinase (PKR-mediated eukaryotic initiation factor (eIF2alpha phosphorylation, leading to the suppression of host and viral protein translation. RVFV NSs promoted post-transcriptional downregulation of PKR early in the course of the infection and suppressed the phosphorylated eIF2alpha accumulation. These data suggested that a combination of RVFV replication and NSs-induced host transcriptional suppression induces PKR-mediated eIF2alpha phosphorylation, while the NSs facilitates efficient viral translation by downregulating PKR and inhibiting PKR-mediated eIF2alpha phosphorylation. Thus, the two distinct functions of the NSs, i.e., the suppression of host transcription, including that of type I interferon mRNAs, and the downregulation of PKR, work together to prevent host innate antiviral functions, allowing efficient replication and survival of RVFV in infected mammalian hosts.

Mapping of zones potentially occupied by Aedes vexans and Culex poicilipes mosquitoes, the main vectors of Rift Valley fever in Senegal

Directory of Open Access Journals (Sweden)

Yves M. Tourre

2008-11-01

Full Text Available A necessary condition for Rift Valley fever (RVF emergence is the presence of Aedes (Aedimorphus vexans and Culex (Culex poicilipes mosquitoes carrying the arbovirus and responsible for the infection. This paper presents a detailed mapping in the Sahelian region of Senegal of zones potentially occupied by these mosquitoes (ZPOMs whose population density is directly linked to ecozones in the vicinity of small ponds. The vectors habitats and breeding sites have been characterized through an integrated approach combining remote sensing technology, geographical information systems, geographical positioning systems and field observations for proper geo-referencing. From five SPOT-5 images (~10 m spatial resolution with appropriate channels, a meridional composite transect of 290 x 60 km was first constructed at the height of the summer monsoon. Subsequent ZPOMs covered major ecozones from north to south with different hydrological environments and different patterns pond distributions. It was found that an overall area of 12,817 ha ± 10% (about 0.8% of the transect is occupied by ponds with an average ZPOM 17 times larger than this (212,813 ha ± 10% or about 14% of the transect. By comparing the very humid year of 2003 with 2006 which had just below normal rainfall, the ZPOMs inter-annual variability was analyzed in a sandy-clayey ecozone with an important hydrofossil riverbed within the Ferlo region of Senegal. Very probably contributing to an increased abundance of vectors by the end of August 2003, it was shown that the aggregate pond area was already about 22 times larger than in August 2006, corresponding to an approximately five times larger total ZPOM. The results show the importance of pin-pointing small ponds (sizes down to 0.1 ha and their geographical distribution in order to assess animal exposure to the RVF vectors.

Mutation of adjacent cysteine residues in the NSs protein of Rift Valley fever virus results in loss of virulence in mice.

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Monteiro, Gaby E R; Jansen van Vuren, Petrus; Wichgers Schreur, Paul J; Odendaal, Lieza; Clift, Sarah J; Kortekaas, Jeroen; Paweska, Janusz T

2018-04-02

The NSs protein encoded by the S segment of Rift Valley fever virus (RVFV) is the major virulence factor, counteracting the host innate antiviral defence. It contains five highly conserved cysteine residues at positions 39, 40, 149, 178 and 194, which are thought to stabilize the tertiary and quaternary structure of the protein. Here, we report significant differences between clinical, virological, histopathological and host gene responses in BALB/c mice infected with wild-type RVFV (wtRVFV) or a genetic mutant having a double cysteine-to-serine substitution at residues 39 and 40 of the NSs protein (RVFV-C39S/C40S). Mice infected with the wtRVFV developed a fatal acute disease; characterized by high levels of viral replication, severe hepatocellular necrosis, and massive up-regulation of transcription of genes encoding type I and -II interferons (IFN) as well as pro-apoptotic and pro-inflammatory cytokines. The RVFV-C39S/C40S mutant did not cause clinical disease and its attenuated virulence was consistent with virological, histopathological and host gene expression findings in BALB/c mice. Clinical signs in mice infected with viruses containing cysteine-to-serine substitutions at positions 178 or 194 were similar to those occurring in mice infected with the wtRVFV, while a mutant containing a substitution at position 149 caused mild, non-fatal disease in mice. As mutant RVFV-C39S/C40S showed an attenuated phenotype in mice, the molecular mechanisms behind this attenuation were further investigated. The results show that two mechanisms are responsible for the attenuation; (1) loss of the IFN antagonistic propriety characteristic of the wtRVFV NSs and (2) the inability of the attenuated mutant to degrade Proteine Kinase R (PKR). Copyright © 2018. Published by Elsevier B.V.

Groundwater fluoride enrichment in an active rift setting: Central Kenya Rift case study

Energy Technology Data Exchange (ETDEWEB)

Olaka, Lydia A., E-mail: lydiaolaka@gmail.com [Department of Geology, University of Nairobi, P.O Box 30197, Nairobi (Kenya); Wilke, Franziska D.H. [Geoforschungs Zentrum, Telegrafenberg, 14473 Potsdam (Germany); Olago, Daniel O.; Odada, Eric O. [Department of Geology, University of Nairobi, P.O Box 30197, Nairobi (Kenya); Mulch, Andreas [Senckenberg Biodiversity and Climate Research Centre, Senckenberganlage 25, 60325 Frankfurt (Germany); Institut für Geowissenschaften, Goethe Universität Frankfurt, Altenhöferallee 1, 60438 Frankfurt (Germany); Musolff, Andreas [UFZ-Helmholtz-Centre for Environmental Research, Department of Hydrogeology, Permoserstr. 15, 04318 Leipzig (Germany)

2016-03-01

Groundwater is used extensively in the Central Kenya Rift for domestic and agricultural demands. In these active rift settings groundwater can exhibit high fluoride levels. In order to address water security and reduce human exposure to high fluoride in drinking water, knowledge of the source and geochemical processes of enrichment are required. A study was therefore carried out within the Naivasha catchment (Kenya) to understand the genesis, enrichment and seasonal variations of fluoride in the groundwater. Rocks, rain, surface and groundwater sources were sampled for hydrogeochemical and isotopic investigations, the data was statistically and geospatially analyzed. Water sources have variable fluoride concentrations between 0.02–75 mg/L. 73% exceed the health limit (1.5 mg/L) in both dry and wet seasons. F{sup −} concentrations in rivers are lower (0.2–9.2 mg/L) than groundwater (0.09 to 43.6 mg/L) while saline lake waters have the highest concentrations (0.27–75 mg/L). The higher values are confined to elevations below 2000 masl. Oxygen (δ{sup 18}O) and hydrogen (δD) isotopic values range from − 6.2 to + 5.8‰ and − 31.3 to + 33.3‰, respectively, they are also highly variable in the rift floor where they attain maximum values. Fluoride base levels in the precursor vitreous volcanic rocks are higher (between 3750–6000 ppm) in minerals such as cordierite and muscovite while secondary minerals like illite and kaolinite have lower remnant fluoride (< 1000 ppm). Thus, geochemical F{sup −} enrichment in regional groundwater is mainly due to a) rock alteration, i.e. through long residence times and natural discharge and/or enhanced leakages of deep seated geothermal water reservoirs, b) secondary concentration fortification of natural reservoirs through evaporation, through reduced recharge and/or enhanced abstraction and c) through additional enrichment of fluoride after volcanic emissions. The findings are useful to help improve water management

Impact of earthquakes on agriculture during the Roman-Byzantine period from pollen records of the Dead Sea laminated sediment

Science.gov (United States)

Leroy, Suzanne A. G.; Marco, Shmuel; Bookman, Revital; Miller, Charlotte S.

2010-03-01

The Dead Sea region holds the archives of a complex relationship between an ever-changing nature and ancient civilisations. Regional pollen diagrams show a Roman-Byzantine period standing out in the recent millennia by its wetter climate that allowed intensive arboriculture. During that period, the Dead Sea formed laminites that display mostly a seasonal character. A multidisciplinary study focused on two earthquakes, 31 BC and AD 363, recorded as seismites in the Ze'elim gully A unit III which has been well dated by radiocarbon in a previous study. The sampling of the sediment was done at an annual resolution starting from a few years before and finishing a decade after each earthquake. A clear drop in agricultural indicators (especially Olea and cereals) is shown. These pollen indicators mostly reflect human activities in the Judean Hills and coastal oases. Agriculture was disturbed in large part of the rift valley where earthquake damage affected irrigation and access to the fields. It took 4 to 5 yr to resume agriculture to previous conditions. Earthquakes must be seen as contributors to factors damaging societies. If combined with other factors such as climatic aridification, disease epidemics and political upheaval, they may lead to civilisation collapse.

K-Ar age data and geochemistry of the Kiwitahi Volcanics, western Hauraki Rift, North Island, New Zealand

Energy Technology Data Exchange (ETDEWEB)

Black, P M [Department of Geology, Auckland University, Auckland (New Zealand); Briggs, R M [Department of Earth Sciences, Waikato University, Hamilton (New Zealand); Itaya, T [Hiruzen Research Institute, Okayama University of Science, Okayama (Japan); Dewes, E R [Department of Earth Sciences, Waikato University, Hamilton (New Zealand); Dunbar, H M [Department of Earth Sciences, Waikato University, Hamilton (New Zealand); Kawasaki, K [Hiruzen Research Institute, Okayama University of Science, Okayama (Japan); Kuschel, E [Department of Geology, Auckland University, Auckland (New Zealand); Smith, I E.M. [Department of Geology, Auckland University, Auckland (New Zealand)

1992-07-01

The Kiwitahi Volcanics of late Miocene age crop out in a number of localities situated along the western side of the Hauraki Rift in northern North Island, New Zealand. They extend from Waiheke Island in the north to Te Tapui in the south. From 19 new K-Ar ages presented here and geochemical data from volcanics at each locality, it is suggested that the Kiwitahi Volcanics should be informally subdivided into five groups: (1) an oldest group of agglomerates and volcanic breccias at northeastern Waiheke, containing pyroxene and hornblende andesites with an age range of 14.4-16.02 Ma; (2) a volcanic centre at Stony Batter (6.85-8.34 Ma) comprised of olivine basaltic andesites which should be assigned to the geochemically and temporally similar Ti Point Volcanics; (3) a group including the andesitic breccias at Ness Valley and the volcanic centres of Miranda (pyroxene basaltic andesite, pyroxene and hornblende andesite, hornblende dacite) and Pukekamaka (hornblende andesites), all within the age range 10.22-12.96 Ma; (4) a separate group at Tahuna (6.36-6.80 Ma) consisting of pyroxene basaltic andesites and pyroxene andesites; and (5) a southern group of Maungatapu, Ruru, Maungakawa, and Te Tapui (5.52-6.23 Ma), forming eroded cones of olivine basaltic andesites, pyroxene basaltic andesites, and pyroxene andesites. The Kiwitahi Volcanics of late Miocene age crop out in a number of localities situated along the western side of the Hauraki Rift in northern North Island, New Zealand. They extend from Waiheke Island in the north to Te Tapui in the south. From 19 new K-Ar ages presented here and geochemical data from volcanics at each locality, it is suggested that the Kiwitahi Volcanics should be informally subdivided into five groups: (1) an oldest group of agglomerates and volcanic breccias at northeastern Waiheke, containing pyroxene and hornblende andesites with an age range of 14.4-16.02 Ma; (2) a volcanic centre at Stony Batter (6.85-8.34 Ma) comprised of olivine

K-Ar age data and geochemistry of the Kiwitahi Volcanics, western Hauraki Rift, North Island, New Zealand

International Nuclear Information System (INIS)

Black, P.M.; Briggs, R.M.; Itaya, T.; Dewes, E.R.; Dunbar, H.M.; Kawasaki, K.; Kuschel, E.; Smith, I.E.M.

1992-01-01

The Kiwitahi Volcanics of late Miocene age crop out in a number of localities situated along the western side of the Hauraki Rift in northern North Island, New Zealand. They extend from Waiheke Island in the north to Te Tapui in the south. From 19 new K-Ar ages presented here and geochemical data from volcanics at each locality, it is suggested that the Kiwitahi Volcanics should be informally subdivided into five groups: (1) an oldest group of agglomerates and volcanic breccias at northeastern Waiheke, containing pyroxene and hornblende andesites with an age range of 14.4-16.02 Ma; (2) a volcanic centre at Stony Batter (6.85-8.34 Ma) comprised of olivine basaltic andesites which should be assigned to the geochemically and temporally similar Ti Point Volcanics; (3) a group including the andesitic breccias at Ness Valley and the volcanic centres of Miranda (pyroxene basaltic andesite, pyroxene and hornblende andesite, hornblende dacite) and Pukekamaka (hornblende andesites), all within the age range 10.22-12.96 Ma; (4) a separate group at Tahuna (6.36-6.80 Ma) consisting of pyroxene basaltic andesites and pyroxene andesites; and (5) a southern group of Maungatapu, Ruru, Maungakawa, and Te Tapui (5.52-6.23 Ma), forming eroded cones of olivine basaltic andesites, pyroxene basaltic andesites, and pyroxene andesites. The Kiwitahi Volcanics of late Miocene age crop out in a number of localities situated along the western side of the Hauraki Rift in northern North Island, New Zealand. They extend from Waiheke Island in the north to Te Tapui in the south. From 19 new K-Ar ages presented here and geochemical data from volcanics at each locality, it is suggested that the Kiwitahi Volcanics should be informally subdivided into five groups: (1) an oldest group of agglomerates and volcanic breccias at northeastern Waiheke, containing pyroxene and hornblende andesites with an age range of 14.4-16.02 Ma; (2) a volcanic centre at Stony Batter (6.85-8.34 Ma) comprised of olivine

Rift systems of the Russian Eastern Arctic shelf and Arctic deep water basins: link between geological history and geodynamics

Directory of Open Access Journals (Sweden)

A. M. Nikishin

2017-01-01

Full Text Available In our study, we have developed a new tectonic scheme of the Arctic Ocean, which is based mainly on seismic profiles obtained in the Arctic-2011, Arctic-2012 and Arctic-2014 Projects implemented in Russia. Having interpreted many seismic profiles, we propose a new seismic stratigraphy of the Arctic Ocean. Our main conclusions are drawn from the interpretation of the seismic profiles and the analysis of the regional geological data. The results of our study show that rift systems within the Laptev, the East Siberian and the Chukchi Seas were formed not earlier than Aptian. The geological structure of the Eurasian, Podvodnikov, Toll and Makarov Basins is described in this paper. Having synthesized all the available data on the study area, we propose the following model of the geological history of the Arctic Ocean: 1. The Canada Basin formed till the Aptian (probably, during Hauterivian-Barremian time. 2. During the Aptian-Albian, large-scale tectonic and magmatic events took place, including plume magmatism in the area of the De Long Islands, Mendeleev Ridge and other regions. Continental rifting started after the completion of the Verkhoyansk-Chukotka orogenу, and rifting occurred on the shelf of the Laptev, East Siberian, North Chukchi and South Chukchi basins, and the Chukchi Plateau; simultaneously, continental rifting started in the Podvodnikov and Toll basins. 3. Perhaps the Late Cretaceous rifting continued in the Podvodnikov and Toll basins. 4. At the end of the Late Cretaceous and Paleocene, the Makarov basin was formed by rifting, although local spreading of oceanic crust during its formation cannot be excluded. 5. The Eurasian Basin started to open in the Early Eocene. We, of course, accept that our model of the geological history of the Arctic Ocean, being preliminary and debatable, may need further refining. In this paper, we have shown a link between the continental rift systems on the shelf and the formation history of the Arctic

Impact of rheological layering on rift asymmetry

Science.gov (United States)

Jaquet, Yoann; Schmalholz, Stefan M.; Duretz, Thibault

2015-04-01

Although numerous models of rift formation have been proposed, what triggers asymmetry of rifted margins remains unclear. Parametrized material softening is often employed to induce asymmetric fault patterns in numerical models. Here, we use thermo-mechanical finite element models that allow softening via thermal weakening. We investigate the importance of lithosphere rheology and mechanical layering on rift morphology. The numerical code is based on the MILAMIN solver and uses the Triangle mesh generator. Our model configuration consists of a visco-elasto-platic layered lithosphere comprising either (1) only one brittle-ductile transition (in the mantle) or (2) three brittle-ductile transitions (one in the upper crust, one in the lower crust and one in the mantle). We perform then two sets of simulations characterized by low and high extensional strain rates (5*10-15 s-1, 2*10-14 s-1). The results show that the extension of a lithosphere comprising only one brittle-ductile transition produces a symmetric 'neck' type rift. The upper and lower crusts are thinned until the lithospheric mantle is exhumed to the seafloor. A lithosphere containing three brittle-ductile transitions favors strain localization. Shear zones at different horizontal locations and generated in the brittle levels of the lithosphere get connected by the weak ductile layers. The results suggest that rheological layering of the lithosphere can be a reason for the generation of asymmetric rifting and subsequent rift morphology.

The origin and evolution of silicic magmas during continental rifting: new constraints from trace elements and oxygen isotopes from Ethiopian volcanoes

Science.gov (United States)

Hutchison, W.; Boyce, A.; Mather, T. A.; Pyle, D. M.; Yirgu, G.; Gleeson, M. L.

2017-12-01

The petrologic diversity of rift magmas is generated by two key processes: interaction with the crust via partial melting or assimilation; and closed-system fractional crystallization of the parental magma. It is not yet known whether these two petrogenetic processes vary spatially between different rift settings, and whether there are any significant secular variations during rift evolution. The Ethiopian Rift is the ideal setting to test these hypotheses because it captures the transition from continental rifting to sea-floor spreading and has witnessed the eruption of large volumes of mafic and silicic volcanic rocks since 30 Ma. We use new oxygen isotope (δ18O) and trace element data to fingerprint fractional crystallisation and partial crustal melting processes in Ethiopia and evaluate spatial variations between three active rift segments. δ18O measurements are used to examine partial crustal melting processes. We find that most δ18O data from basalts to rhyolites fall within the bounds of modelled fractional crystallization trajectories (i.e., 5.5-6.5 ‰). Few samples deviate from this trend, emphasising that fractional crystallization is the dominant petrogenetic processes and that little fusible Precambrian crustal material (δ18O of 7-18 ‰) remain to be assimilated beneath the magmatic segments. Trace element systematics (e.g., Ba, Sr, Rb, Th and Zr) further underscore the dominant role of fractional crystallization but also reveal important variations in the degree of melt evolution between the volcanic systems. We find that the most evolved silicic magmas, i.e., those with greatest peralkalinity (molar Na2O+K2O>Al2O3), are promoted in regions of lowest magma flux off-axis and along rift. Our findings provide new information on the nature of the crust beneath Ethiopia's active magmatic segments and also have relevance for understanding ancient rift zones and the geotectonic settings that promote genesis of economically-valuable mineral deposits.

Recognized Multiple Rifts of the Neoproterozoic in the Initiation of the Tarim Craton (NW China) and Their Tectonic Implications

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He, B.; Jiao, C.; Huang, T.; Zhou, X.; Cai, Z.; Cao, Z.; Jiang, Z.; Cui, J.; Yu, Z.; Chen, W.

2017-12-01

The Tarim Basin is the largest, oil-bearing and superimposed basin in the northwest of China. The development and tectonic property of the initial Tarim basin have been acutely disputed and remain enigmatic. Urgently need to reveal the origin and formation dynamics of the Tarim Carton and evaluate the potential of the deep energy resources. However, covered by vast desert and huge-thickness sedimentary strata, suffered by multiple tectonic movements, seismic data with low signal- to- noise ratio in the deep are the critical difficulties. We analyse 4 field outcrops, 18 wells, 27 reprocessed seismic reflection profiles with high SNR across the basin and many ancillary ones and aeromagnetic data. We find about 20 normal fault-controlled rift depressions of the Cryogenian and Ediacaran scattered in the Tarim basin, which developed on the Precambrian metamorphic and crystalline basements and covered by the epeiric sea and basin facies sediments of the Lower Cambrian. The structural styles of the rifts are mainly half grabens, symmetrical troughs and horst-grabens. The regional differences exist obviously in spatial and temporal. The WNW-ESE-trending faults occur in the central part and northern of the basin and the NE, and the NEE-trending faults occur in the southern parts, which response with the anomaly of aeromagnetic. Some main faults of the Ediacaran inherited from the Cryogenian and some occurred newly, the more rifting depressions occurred during the Ediacaran. The extensional NNW-SSE-oriented and NNE-SSW-oriented paleostress field occurred simultaneously during rifting, and accompanied with the clockwise shearing. According to the activities of syn-sedimentary faults, magmatic events and sediments, the tectonic properties of the rifts are different depending on their locations in the Tarim craton. The rifting phases mainly occurred from 780 Ma to 615 Ma. The formation of rifts were associated with the opening of the South Tianshan Ocean and the South Altun

Rifting and Subsidence in the Gulf of Mexico: Implications for Syn-rift, Sag, and Salt Sections, and Subsequent Paleogeography

Science.gov (United States)

Pindell, J. L.; Graham, R.; Horn, B.

2013-05-01

Thick (up to 5 km), rapid (depression where basement had already subsided tectonically, and thus could receive up to 5 km of salt, roughly the isostatic maximum on exhumed mantle, hyper-thinned continent, or new ocean crust. ION-GXT and other seismic data along W Florida and NW Yucatán show that (1) mother salt was only 1 km thick in these areas, (2) that these areas were depositionally connected to areas of thicker deposition, and (3) the top of all salt was at global sea level, and hence the sub-salt unconformity along Florida and Yucatán was only 1 km deep by end of salt deposition. These observations fit the air-filled chasm hypothesis; however, two further observations make that mechanism highly improbable: (1) basinward limits of sub-salt unconformities along Florida/Yucatán are deeper than top of adjacent ocean crust emplaced at ~2.7 km subsea (shown by backstripping), and (2) deepest abyssal sediments over ocean crust onlap the top of distal salt, demonstrating that the salt itself was rapidly drowned after deposition. Study of global ION datasets demonstrates the process of "rapid outer marginal collapse" at most margins, which we believe is achieved by low-angle detachment on deep, landward-dipping, Moho-equivalent surfaces such that outer rifted margins are hanging walls of crustal scale half-grabens over mantle. The tectonic accommodation space produced (up to 3 km, < 3 Ma) can be filled by ~5 km of sag/salt sequences with little apparent hanging wall rifting. When salt (or other) deposition lags behind, or ends during, outer marginal collapse, deep-water settings result. We suggest that this newly identified, "outer marginal detachment phase", normally separates the traditional "rift" from "drift" stages during continental margin creation. Importantly, this 2-3 km of subsidence presently is neither treated as tectonic nor as thermal in traditional subsidence analysis; thus, Beta estimates may be excessive at many outer margins. Outer marginal

Rift Valley fever virus-infected mosquito ova and associated pathology: possible implications for endemic maintenance

Directory of Open Access Journals (Sweden)

Romoser WS

2011-09-01

Full Text Available William S Romoser1, Marco Neira Oviedo1, Kriangkrai Lerdthusnee2, Lisa A Patrican3, Michael J Turell4, David J Dohm4, Kenneth J Linthicum5, Charles L Bailey61Department of Biomedical Sciences, College of Osteopathic Medicine, Tropical Disease Institute, Ohio University, Athens, Ohio, USA; 2Department of Entomology, Faculty of Agriculture, Kasetsart University, Bangkok, Thailand; 3Infectious Disease Division, National Center for Medical Intelligence, Fort Detrick, Frederick, Maryland, USA; 4Department of Vector Assessment, Virology Division, United States Army Medical Research Institute of Infectious Diseases, Fort Detrick, Frederick, Maryland, USA; 5Center for Medical, Agricultural, and Veterinary Entomology, United States Department of Agriculture – Agricultural Research Service, Gainesville, Florida, USA; 6National Center for Biodefense and Infectious Disease, School of Systems Biology, College of Science, George Mason University, Manassas, Virginia, USABackground: Endemic/enzootic maintenance mechanisms like vertical transmission (pathogen passage from infected adults to their offspring are central in the epidemiology of zoonotic pathogens. In Kenya, Rift Valley fever virus (RVFV may be maintained by vertical transmission in ground-pool mosquitoes such as Aedes mcintoshi. RVFV can cause serious morbidity and mortality in humans and livestock. Past epidemics/epizootics have occurred in sub-Saharan Africa but, since the late 1970s, RVFV has also appeared in North Africa and the Middle East. Preliminary results revealed RVFV-infected eggs in Ae. mcintoshi after virus injection into the hemocoel after the first of two blood meals, justifying further study.Methods: Mosquitoes were collected from an artificially flooded water-catching depression along a stream in Kenya, shipped live to the USA, and studied using an immunocytochemical method for RVFV-antigen localization in mosquito sections.Results and conclusion: After virus injection into the

Fault kinematics and tectonic stress in the seismically active Manyara Dodoma Rift segment in Central Tanzania Implications for the East African Rift

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Macheyeki, Athanas S.; Delvaux, Damien; De Batist, Marc; Mruma, Abdulkarim

2008-07-01

The Eastern Branch of the East African Rift System is well known in Ethiopia (Main Ethiopian Rift) and Kenya (Kenya or Gregory Rift) and is usually considered to fade away southwards in the North Tanzanian Divergence, where it splits into the Eyasi, Manyara and Pangani segments. Further towards the south, rift structures are more weakly expressed and this area has not attracted much attention since the mapping and exploratory works of the 1950s. In November 4, 2002, an earthquake of magnitude Mb = 5.5 struck Dodoma, the capital city of Tanzania. Analysis of modern digital relief, seismological and geological data reveals that ongoing tectonic deformation is presently affecting a broad N-S trending belt, extending southward from the North Tanzanian Divergence to the region of Dodoma, forming the proposed "Manyara-Dodoma Rift segment". North of Arusha-Ngorongoro line, the rift is confined to a narrow belt (Natron graben in Tanzania) and south of it, it broadens into a wide deformation zone which includes both the Eyasi and Manyara grabens. The two-stage rifting model proposed for Kenya and North Tanzania also applies to the Manyara-Dodoma Rift segment. In a first stage, large, well-expressed topographic and volcanogenic structures were initiated in the Natron, Eyasi and Manyara grabens during the Late Miocene to Pliocene. From the Middle Pleistocene onwards, deformations related to the second rifting stage propagated southwards to the Dodoma region. These young structures have still limited morphological expressions compared to the structures formed during the first stage. However, they appear to be tectonically active as shown by the high concentration of moderate earthquakes into earthquake swarms, the distribution of He-bearing thermal springs, the morphological freshness of the fault scarps, and the presence of open surface fractures. Fault kinematic and paleostress analysis of geological fault data in basement rocks along the active fault lines show that recent

Study of southern CHAONAN sag lower continental slope basin deposition character in Northern South China Sea

Science.gov (United States)

Tang, Y.

2009-12-01

Northern South China Sea Margin locates in Eurasian plate,Indian-Australia plate,Pacific Plates.The South China Sea had underwent a complicated tectonic evolution in Cenozoic.During rifting,the continental shelf and slope forms a series of Cenozoic sedimentary basins,including Qiongdongnan basin,Pearl River Mouth basin,Taixinan basin.These basins fill in thick Cenozoic fluviolacustrine facies,transitional facies,marine facies,abyssal facies sediment,recording the evolution history of South China Sea Margin rifting and ocean basin extending.The studies of tectonics and deposition of depression in the Southern Chaonan Sag of lower continental slope in the Norther South China Sea were dealt with,based on the sequence stratigraphy and depositional facies interpretation of seismic profiles acquired by cruises of“China and Germany Joint Study on Marine Geosciences in the South China Sea”and“The formation,evolution and key issues of important resources in China marginal sea",and combining with ODP 1148 cole and LW33-1-1 well.The free-air gravity anomaly of the break up of the continental and ocean appears comparatively low negative anomaly traps which extended in EW,it is the reflection of passive margin gravitational effect.Bouguer gravity anomaly is comparatively low which is gradient zone extended NE-SW.Magnetic anomaly lies in Magnetic Quiet Zone at the Northern Continental Margin of the South China Sea.The Cenozoic sediments of lower continental slope in Southern Chaonan Sag can be divided into five stratum interface:SB5.5,SB10.5,SB16.5,SB23.8 and Hg,their ages are of Pliocene-Quaternary,late Miocene,middle Miocene,early Miocene,paleogene.The tectonic evolution of low continental slope depressions can be divided into rifting,rifting-depression transitional and depression stages,while their depositional environments change from river to shallow marine and abyssa1,which results in different topography in different stages.The topographic evolvement in the study

Seismicity of the Earth 1900-2013 East African Rift

Science.gov (United States)

Hayes, Gavin P.; Jones, Eric S.; Stadler, Timothy J.; Barnhart, William D.; McNamara, Daniel E.; Benz, Harley M.; Furlong, Kevin P.; Villaseñor, Antonio; Hayes, Gavin P.; Jones, Eric S.; Stadler, Timothy J.; Barnhart, William D.; McNamara, Daniel E.; Benz, Harley M.; Furlong, Kevin P.; Villaseñor, Antonio

2014-01-01

The East African Rift system (EARS) is a 3,000-km-long Cenozoic age continental rift extending from the Afar triple junction, between the horn of Africa and the Middle East, to western Mozambique. Sectors of active extension occur from the Indian Ocean, west to Botswana and the Democratic Republic of the Congo (DRC). It is the only rift system in the world that is active on a continent-wide scale, providing geologists with a view of how continental rifts develop over time into oceanic spreading centers like the Mid-Atlantic Ridge.

Laboratory safe detection of nucleocapsid protein of Rift Valley fever virus in human and animal specimens by a sandwich ELISA.

Science.gov (United States)

Jansen van Vuren, P; Paweska, J T

2009-04-01

A safe laboratory procedure, based on a sandwich ELISA (sAg-ELISA), was developed and evaluated for the detection of nucleocapsid protein (NP) of Rift Valley fever virus (RVFV) in specimens inactivated at 56 degrees C for 1h in the presence of 0.5% Tween-20 (v/v) before testing. Polyclonal capture and detection immune sera were generated respectively in sheep and rabbits immunized with recombinant NP antigen. The assay was highly repeatable and specific; it detected strains of RVFV from the entire distributional range of the disease, isolated over a period of 53 years; no cross-reactivity with genetically related African phleboviruses or other members of the family Bunyaviridae was observed. In specimens spiked with RVFV, including human and animal sera, homogenates of liver and spleen tissues of domestic ruminants, and Anopheles mosquito homogenates, the sAg-ELISA detection limit ranged from log(10)10(2.2) to 10(3.2) TCID(50)/reaction volume. The ELISA detected NP antigen in spiked bovine and sheep liver homogenates up to at least 8 days of incubation at 37 degrees C whereas infectious virus could not be detected at 48h incubation in these adverse conditions. Compared to virus isolation from sera from RVF patients and sheep infected experimentally, the ELISA had 67.7% and 70% sensitivity, and 97.97% and 100% specificity, respectively. The assay was 100% accurate when testing tissues of various organs from mice infected experimentally and buffalo foetuses infected naturally. The assay was able to detect NP antigen in infective culture supernatants 16-24h before cytopathic effects were observed microscopically and as early as 8h after inoculation with 10(5.8) TCID(50)/ml of RVFV. This ability renders the assay for rapid identification of the virus when its primary isolation is attempted in vitro. As a highly specific, safe and simple assay format, the sAg-ELISA represents a valuable diagnostic tool for use in less equipped laboratories in Africa, and for routine

Ore-forming environment and ore-forming system of carbonaceous-siliceous-pelitic rock type uranium deposit in China

International Nuclear Information System (INIS)

Qi Fucheng; Zhang Zilong; Li Zhixing; He Zhongbo; Wang Wenquan

2012-01-01

It is proposed that there are four types of ore-forming systems about carbonaceous-siliceous-pelitic rock type uranium deposit in China based on systematic study on structural environment and distribution regularity of uraniferous construction of marine carbonaceous-siliceous-pelitic rock in China: continental margin rift valley ore-forming systems, continental margin rifting deep fracture zone ore-forming systems, landmass boundary borderland basin ore-forming systems and epicontinental mobile belt downfaulted aulacogen ore-forming systems. It is propounded definitely that it is controlled by margin rift valley ore-forming systems and continental margin rifting deep fracture zone ore-forming systems for large-scale uranium mineralization of carbonaceous-siliceous-pelitic rock type uranium deposit in China, which is also controlled by uraniferous marine carbonaceous-siliceous-pelitic rock construction made up of silicalite, siliceous phosphorite and carbonaceous-siliceous-pelitic rock, which settled down accompany with submarine backwash and sub marine volcanic eruption in margin rift valley and continental margin rifting mineralizing environment. Continental mar gin rift valley and continental margin rifting thermal sedimentation or exhalation sedimentation is the mechanism of forming large-scale uraniferous marine carbonaceous-siliceous-pelitic rock construction Early Palaeozoic Era in China or large-scale uranium-polymetallic mineralization. (authors)

Re-emergence of Rift Valley fever virus in Barkedji (Senegal, West Africa) in 2002-2003: identification of new vectors and epidemiological implications.

Science.gov (United States)

Ba, Y; Sall, A A; Diallo, D; Mondo, M; Girault, L; Dia, I; Diallo, M

2012-09-01

The Rift Valley fever virus (RVFV) is a threat that must not be neglected, as the consequences of RVFV are dramatic, both for human and animal health. This virus is a zoonotic virus that already has demonstrated a real capacity for re-emerging after long periods of silence, as observed in Barkedji (Senegal, West Africa) in 2002. In this article we present the 2nd emergence in Barkedji after the 1st manifestation in 1993, and for the 1st time the circulation of RVFV during 2 consecutive years among mosquito populations in Senegal. As part of the entomological surveillance program undertaken since 1990 to detect circulation of the RVFV in Barkedji, 108,336 mosquitoes belonging to 34 species and 5 genera were collected in 2002-2003. Aedes vexans and Culex poicilipes, previously known to be vectors of RVFV in Senegal, comprised 88.7% of the total collection. In 2002, Ae. vexans was the most abundant mosquito, followed by Cx. poicilipes; the opposite situation was observed in 2003. In 2002, 29 and 10 RVFV isolates were obtained from Cx. poicilipes (minimum infection rate [MIR] = 0.13%) and Ae. vexans (MIR = 0.02%) pools, respectively and the MIR for the 2 species were significantly different (chi2 = 34.65; df = 1, P < 0.001). In 2003, 7 RVFV strains were isolated from Cx. poicilipes (3, MIR = 0.03), Mansonia africana (2, MIR = 0.08), Ae. fowleri (1), and Ma. uniformis (1, MIR = 0.05). The 3 latter species were found to be associated with RVFV for the 1st time in Senegal. A significant decrease in MIR was observed from 2002 to 2003 (chi2 6.28; df = 1, P = 0.01) for Cx. poicilipes, the only species involved in the transmission during the 2 sampling years.

Rift Valley Fever Vaccine Virus Clone 13 Is Able to Cross the Ovine Placental Barrier Associated with Foetal Infections, Malformations, and Stillbirths.

Directory of Open Access Journals (Sweden)

Birgit Makoschey

2016-03-01

Full Text Available Rift Valley fever virus (RVFV is a mosquito-borne pathogen that affects domesticated ruminants and occasionally humans. Classical RVF vaccines are based on formalin-inactivated virus or the live-attenuated Smithburn strain. The inactivated vaccine is highly safe but requires multiple administrations and yearly re-vaccinations. Although the Smithburn vaccine provides solid protection after a single vaccination, this vaccine is not safe for pregnant animals. An alternative live-attenuated vaccine, named Clone 13, carries a large natural deletion in the NSs gene which encodes the major virulence factor of the virus. The Clone 13 vaccine was previously shown to be safe for young lambs and calves. Moreover, a study in pregnant ewes suggested that the vaccine could also be applied safely during gestation. To anticipate on a possible future incursion of RVFV in Europe, we have evaluated the safety of Clone 13 for young lambs and pregnant ewes. In line with the guidelines from the World Organisation for Animal health (Office International des Epizooties, OIE and regulations of the European Pharmacopeia (EP, these studies were performed with an overdose. Our studies with lambs showed that Clone 13 dissemination within vaccinated animals is very limited. Moreover, the Clone 13 vaccine virus was not shed nor spread to in-contact sentinels and did not revert to virulence upon animal-to-animal passage. Importantly, a large experiment with pregnant ewes demonstrated that the Clone 13 virus is able to spread to the fetus, resulting in malformations and stillbirths. Altogether, our results suggest that Clone 13 can be applied safely in lambs, but that caution should be taken when Clone 13 is used in pregnant animals, particularly during the first trimester of gestation.

Safety and immunogenicity of Onderstepoort Biological Products’ Rift Valley fever Clone 13 vaccine in sheep and goats under field conditions in Senegal

Directory of Open Access Journals (Sweden)

Modou M. Lo

2015-05-01

Full Text Available This blinded field safety study was conducted in Senegal to assess safety and immunogenicity of administration of the registered dose of Rift Valley fever virus (RVFV Clone 13 vaccine (Onderstepoort Biological Products to sheep and goats of West African breeds under natural conditions. A total of 267 small ruminants (220 sheep, 47 goats were included; half received RVFV Clone 13 vaccine at the recommended dose and half received the diluent (as placebo only. The study was performed on three commercial farms in the northern and eastern region of Senegal in accordance with veterinary good clinical practices. The animals were observed daily for 3 days after vaccination, and then weekly for 1 year. In both sheep and goats vaccinated against RVFV seroconversion rates above 70% were recorded. No seroconversion related to RVFV was observed in placebo-treated animals. No statistically significant differences were determined between placebo and vaccinated groups for mean rectal temperatures for the first 3 days after administration (p > 0.05. No abnormal clinical signs related to treatment were noted, and only one slight injection site reaction was observed in one vaccinated animal for 2 days after vaccination. Out of 176 births assessed over 1 year (93 from the vaccinated group, 83 from the placebo group, 9 were abnormal in the placebo group and 3 in the vaccinated group (p > 0.05. The frequency of adverse events was similar in the placebo and vaccinated groups. RVFV Clone 13 vaccine administered according to the manufacturer’s instructions was safe and well tolerated in West African breeds of sheep and goats, including animals of approximately 6 months of age and pregnant females, under field conditions in Senegal. Antibody levels persisted up to 1 year after vaccination.

Rift Valley Fever Vaccine Virus Clone 13 Is Able to Cross the Ovine Placental Barrier Associated with Foetal Infections, Malformations, and Stillbirths

Science.gov (United States)

Makoschey, Birgit; van Kilsdonk, Emma; Hubers, Willem R.; Vrijenhoek, Mieke P.; Smit, Marianne; Wichgers Schreur, Paul J.; Kortekaas, Jeroen; Moulin, Véronique

2016-01-01

Rift Valley fever virus (RVFV) is a mosquito-borne pathogen that affects domesticated ruminants and occasionally humans. Classical RVF vaccines are based on formalin-inactivated virus or the live-attenuated Smithburn strain. The inactivated vaccine is highly safe but requires multiple administrations and yearly re-vaccinations. Although the Smithburn vaccine provides solid protection after a single vaccination, this vaccine is not safe for pregnant animals. An alternative live-attenuated vaccine, named Clone 13, carries a large natural deletion in the NSs gene which encodes the major virulence factor of the virus. The Clone 13 vaccine was previously shown to be safe for young lambs and calves. Moreover, a study in pregnant ewes suggested that the vaccine could also be applied safely during gestation. To anticipate on a possible future incursion of RVFV in Europe, we have evaluated the safety of Clone 13 for young lambs and pregnant ewes. In line with the guidelines from the World Organisation for Animal health (Office International des Epizooties, OIE) and regulations of the European Pharmacopeia (EP), these studies were performed with an overdose. Our studies with lambs showed that Clone 13 dissemination within vaccinated animals is very limited. Moreover, the Clone 13 vaccine virus was not shed nor spread to in-contact sentinels and did not revert to virulence upon animal-to-animal passage. Importantly, a large experiment with pregnant ewes demonstrated that the Clone 13 virus is able to spread to the fetus, resulting in malformations and stillbirths. Altogether, our results suggest that Clone 13 can be applied safely in lambs, but that caution should be taken when Clone 13 is used in pregnant animals, particularly during the first trimester of gestation. PMID:27031621

Combining hydrologic and groundwater modelling to characterize a regional aquifer system within a rift setting (Gidabo River Basin, Main Ethiopian Rift)

Science.gov (United States)

Birk, Steffen; Mechal, Abraham; Wagner, Thomas; Dietzel, Martin; Leis, Albrecht; Winkler, Gerfried; Mogessie, Aberra

2016-04-01

The development of groundwater resources within the Ethiopian Rift is complicated by the strong physiographic contrasts between the rift floor and the highland and by the manifold hydrogeological setting composed of volcanic rocks of different type and age that are intersected by numerous faults. Hydrogeochemical and isotope data from various regions within the Ethiopian Rift suggest that the aquifers within the semi-arid rift floor receive a significant contribution of groundwater flow from the humid highland. For example, the major ion composition of groundwater samples from Gidabo River Basin (3302 km²) in the southern part of the Main Ethiopian Rift reveals a mixing trend from the highland toward the rift floor; moreover, the stable isotopes of water, deuterium and O-18, of the rift-floor samples indicate a component recharged in the highland. This work aims to assess if the hydrological and hydrogeological data available for Gidabo River Basin is consistent with these findings and to characterize the regional aquifer system within the rift setting. For this purpose, a two-step approach is employed: First, the semi-distributed hydrological model SWAT is used to obtain an estimate of the spatial and temporal distribution of groundwater recharge within the watershed; second, the numerical groundwater flow model MODFLOW is employed to infer aquifer properties and groundwater flow components. The hydrological model was calibrated and validated using discharge data from three stream gauging stations within the watershed (Mechal et al., Journal of Hydrology: Regional Studies, 2015, doi:10.1016/j.ejrh.2015.09.001). The resulting recharge distribution exhibits a strong decrease from the highland, where the mean annual recharge amounts to several hundred millimetres, to the rift floor, where annual recharge largely is around 100 mm and below. Using this recharge distribution as input, a two-dimensional steady-state groundwater flow model was calibrated to hydraulic

Petrological Constraints on Melt Generation Beneath the Asal Rift (Djibouti)

Science.gov (United States)

Pinzuti, P.; Humler, E.; Manighetti, I.; Gaudemer, Y.; Bézos, A.

2010-12-01

The temporal evolution of the mantle melting processes in the Asal Rift is evaluated from the chemical composition of 95 lava flows sampled along 10 km of the rift axis and 8 km off-axis (that is for the last 650 ky). The major element composition and the trace element ratios of aphyric basalts across the Asal Rift show a symmetric pattern relative to the rift axis and preserved a clear signal of mantle melting depth variations. FeO, Fe8.0, Sm/YbN and Zr/Y increase, whereas SiO2 and Lu/HfN decrease from the rift axis to the rift shoulders. These variations are qualitatively consistent with a shallower melting beneath the rift axis than off-axis and the data show that the melting regime is inconsistent with a passive upwelling model. In order to quantify the depth range and extent of melting, we invert Na8.0 and Fe8.0 contents of basalts based on a pure active upwelling model. Beneath the rift axis, melting paths are shallow, from 60 to 30 km. These melting paths are consistent with adiabatic melting in normal-temperature asthenosphere, beneath an extensively thinned mantle lithosphere. In contrast, melting on the rift shoulders occurred beneath a thick mantle lithosphere and required mantle solidus temperature 180°C hotter than normal (melting paths from 110 to 75 km). The calculated rate of lithospheric thinning is high (6.0 cm yr-1) and could explain the survival of a metastable garnet within the mantle at depth shallower than 90 km beneath the modern Asal Rift.

Catastrophic flooding origin of shelf valley systems in the English Channel.

Science.gov (United States)

Gupta, Sanjeev; Collier, Jenny S; Palmer-Felgate, Andy; Potter, Graeme

2007-07-19

Megaflood events involving sudden discharges of exceptionally large volumes of water are rare, but can significantly affect landscape evolution, continental-scale drainage patterns and climate change. It has been proposed that a significant flood event eroded a network of large ancient valleys on the floor of the English Channel-the narrow seaway between England and France. This hypothesis has remained untested through lack of direct evidence, and alternative non-catastrophist ideas have been entertained for valley formation. Here we analyse a new regional bathymetric map of part of the English Channel derived from high-resolution sonar data, which shows the morphology of the valley in unprecedented detail. We observe a large bedrock-floored valley that contains a distinct assemblage of landforms, including streamlined islands and longitudinal erosional grooves, which are indicative of large-scale subaerial erosion by high-magnitude water discharges. Our observations support the megaflood model, in which breaching of a rock dam at the Dover Strait instigated catastrophic drainage of a large pro-glacial lake in the southern North Sea basin. We suggest that megaflooding provides an explanation for the permanent isolation of Britain from mainland Europe during interglacial high-sea-level stands, and consequently for patterns of early human colonisation of Britain together with the large-scale reorganization of palaeodrainage in northwest Europe.

Jurassic domes in the North Sea - northern North Atlantic region

Energy Technology Data Exchange (ETDEWEB)

Surlyk, F. [Univ. of Copenhagen, Geological Inst., Copenhagen (Denmark)

1996-12-31

The stratigraphic and tectonic evolution of the Jurassic of East Greenland, the Norwegian Shelf and the North Sea is remarkably similar. A major Middle Jurassic unconformity occurs in all three areas. In the North Sea it is commonly termed the `Mid-Cimmerian Unconformity` and is characterized by progressive truncation of the underlying section towards a centre at the triple junction between the Central Graben, Viking Graben and Moray Firth. Strata above the unconformity show a progressive Late Aalenian-Early Kimmeridgian onlap in the same direction. These relations have been interpreted as caused by Early Jurassic uplift and of a major thermal dome in the central North Sea, followed by Medial and Late Jurassic rifting, erosion, deflation and transgression of the dome. The East Greenland unconformity shows progressive truncation of underlying strata from south to north, and Bajocian to Callovian onlap in the same direction. The same pattern seems to be developed on the conjugate Norwegian margin. This suggests the possibility that the three unconformities have similar causes for their development. It is proposed that major rift domes formed in the Central North Sea and in the Greenland-Norway seaway in Early Jurassic times. The domes were eroded and gradually deflated during Medial Jurassic times and were finally submerged by the Late Oxfordian-Kimmeridgian. They were associated with volcanism and rifting which was delayed with respect to dome initiation. Roughly contemperaneous domes were present west of Britain, north of the Porcupine Seabight, and in Scania, southern Sweden, as reflected by development of asymmetrical unconformities showing progressive truncation of underlying strata, onlap of overlying Jurassic strata, and associated intrusive and extrusive volcanism. The domes are related to impingement of the heads of transient mantle plumes at the base of the lithosphere. The associated unconformities are thus of non-eustatic nature. Domal uplift and

Diverse Eruptions at Approximately 2,200 Years B.P. on the Great Rift, Idaho: Inferences for Magma Dynamics Along Volcanic Rift Zones

Science.gov (United States)

Hughes, S. S.; Nawotniak, S. E. Kobs; Borg, C.; Mallonee, H. C.; Purcell, S.; Neish, C.; Garry, W. B.; Haberle, C. W.; Lim, D. S. S.; Heldmann, J. L.

2016-01-01

Compositionally and morphologically diverse lava flows erupted on the Great Rift of Idaho approximately 2.2 ka (kilo-annum, 1000 years ago) during a volcanic "flare-up" of activity following an approximately 2 ky (kiloyear, 1000 years) hiatus in eruptions. Volcanism at Craters of the Moon (COTM), Wapi and Kings Bowl lava fields around this time included primitive and evolved compositions, separated over 75 kilometers along the approximately 85 kilometers-long rift, with striking variability in lava flow emplacement mechanisms and surface morphologies. Although the temporal associations may be coincidental, the system provides a planetary analog to better understand magma dynamics along rift systems, including that associated with lunar floor-fractured craters. This study aims to help bridge the knowledge gap between ancient rift volcanism evident on the Moon and other terrestrial planets, and active rift volcanism, e.g., at Hawai'i and Iceland.

Transient cracks and triple junctions induced by Cocos-Nazca propagating rift

Science.gov (United States)

Schouten, H.; Smith, D. K.; Zhu, W.; Montesi, L. G.; Mitchell, G. A.; Cann, J. R.

2009-12-01

The Galapagos triple junction is a ridge-ridge-ridge triple junction where the Cocos, Nazca, and Pacific plates meet around the Galapagos microplate (GMP). On the Cocos plate, north of the large gore that marks the propagating Cocos-Nazca (C-N) Rift, a 250-km-long and 50-km-wide band of NW-SE-trending cracks crosscuts the N-S-trending abyssal hills of the East Pacific Rise (EPR). These appear as a succession of minor rifts, accommodating some NE-SW extension of EPR-generated seafloor. The rifts successively intersected the EPR in triple junctions at distances of 50-100 km north of the tip of the C-N Rift. We proposed a simple crack interaction model to explain the location of the transient rifts and their junction with the EPR. The model predicts that crack locations are controlled by the stress perturbation along the EPR, induced by the dominant C-N Rift, and scaled by the distance of its tip to the EPR (Schouten et al., 2008). The model also predicts that tensile stresses are symmetric about the C-N Rift and thus, similar cracks should have occurred south of the C-N Rift prior to formation of the GMP about 1 Ma. There were no data at the time to test this prediction. In early 2009 (AT 15-41), we mapped an area on the Nazca plate south of the C-N rift out to 4 Ma. The new bathymetric data confirm the existence of a distinctive pattern of cracks south of the southern C-N gore that mirrors the pattern on the Cocos plate until about 1 Ma, and lends support to the crack interaction model. The envelope of the symmetric cracking pattern indicates that the distance between the C-N Rift tip and the EPR varied between 40 and 65 km during this time (1-4 Ma). The breakdown of the symmetry at 1 Ma accurately dates the onset of a southern plate boundary of the GMP, now Dietz Deep Rift. At present, the southern rift boundary of the GMP joins the EPR with a steep-sided, 80 km long ridge. This ridge releases the stress perturbation otherwise induced along the EPR by elastic

Orogenic structural inheritance and rifted passive margin formation

Science.gov (United States)

Salazar Mora, Claudio A.; Huismans, Ritske S.

2016-04-01

Structural inheritance is related to mechanical weaknesses in the lithosphere due to previous tectonic events, e.g. rifting, subduction and collision. The North and South Atlantic rifted passive margins that formed during the breakup of Western Gondwana, are parallel to the older Caledonide and the Brasiliano-Pan-African orogenic belts. In the South Atlantic, 'old' mantle lithospheric fabric resulting from crystallographic preferred orientation of olivine is suggested to play a role during rifted margin formation (Tommasi and Vauchez, 2001). Magnetometric and gravimetric mapping of onshore structures in the Camamu and Almada basins suggest that extensional faults are controlled by two different directions of inherited older Brasiliano structures in the upper lithosphere (Ferreira et al., 2009). In the South Atlantic Campos Basin, 3D seismic data indicate that inherited basement structures provide a first order control on basin structure (Fetter, 2009). Here we investigate the role of structural inheritance on the formation of rifted passive margins with high-resolution 2D thermo-mechanical numerical experiments. The numerical domain is 1200 km long and 600 km deep and represents the lithosphere and the sublithospheric mantle. Model experiments were carried out by creating self-consistent orogenic inheritance where a first phase of orogen formation is followed by extension. We focus in particular on the role of varying amount of orogenic shortening, crustal rheology, contrasting styles of orogen formation on rifted margin style, and the time delay between orogeny and subsequent rifted passive formation. Model results are compared to contrasting structural styles of rifted passive margin formation as observed in the South Atlantic. Ferreira, T.S., Caixeta, J.M., Lima, F.D., 2009. Basement control in Camamu and Almada rift basins. Boletim de Geociências da Petrobrás 17, 69-88. Fetter, M., 2009. The role of basement tectonic reactivation on the structural evolution

Molecular Rift: Virtual Reality for Drug Designers.

Science.gov (United States)

Norrby, Magnus; Grebner, Christoph; Eriksson, Joakim; Boström, Jonas

2015-11-23

Recent advances in interaction design have created new ways to use computers. One example is the ability to create enhanced 3D environments that simulate physical presence in the real world--a virtual reality. This is relevant to drug discovery since molecular models are frequently used to obtain deeper understandings of, say, ligand-protein complexes. We have developed a tool (Molecular Rift), which creates a virtual reality environment steered with hand movements. Oculus Rift, a head-mounted display, is used to create the virtual settings. The program is controlled by gesture-recognition, using the gaming sensor MS Kinect v2, eliminating the need for standard input devices. The Open Babel toolkit was integrated to provide access to powerful cheminformatics functions. Molecular Rift was developed with a focus on usability, including iterative test-group evaluations. We conclude with reflections on virtual reality's future capabilities in chemistry and education. Molecular Rift is open source and can be downloaded from GitHub.

Volcanism in the Sumisu Rift. Pt. 2

International Nuclear Information System (INIS)

Hochstaedter, A.G.; Gill, J.B.; Morris, J.D.

1990-01-01

A bimodal suite of volcanic rocks collected from the Sumisu Rift by ALVIN provide present day example of the first magmatic products of arc rifting during the initiation of back-arc spreading. The trace element and isotopic composition of these rocks, which are contemporaneous with island arc tholeiite lavas of the Izu-Ogasawara arc 20 km to the east, differ from those of arc rocks and N-MORB in their relative incorporation of both subduction-related and non-subduction-related components. Subduction-related components, i.e., those that distinguish volcanic arc basalts from N-MORB, are less pronounced in rift lavas than in arc lavas. Alkali and alkaline earth to high field strength element and REE ratios as well as 87 Sr/ 86 Sr are intermediate between those of N-MORB and Izu arc lavas and indicate that Sumisu Rift basalts are similar to BABB erupted in other, more mature back-arc basins. These results show that back-arc basins may begin their magmatic evolution with BABB rather than more arc-like lavas. Evidence of non-subduction related components remains after the effects of subduction related components are removed or accounted for. Compared to the arc, higher HFSE and REE concentrations, contrasting REE patterns, and ≤ε Nd in the rift reflect derivation of rift lavas from more enriched components. Although SR basalt resembles E-MORB in many trace element ratios, it is referred to as BABB because low concentrations of Nb are similar to those in volcanic arcs and H 2 O/REE and H 2 O/K 2 O exceed those of E-MORB. Differences in HREE pattern and ε Nd require that the E-MORB characteristics result from source heterogeneities and not lower degrees of melting. Enriched mantle beneath the rift may reflect enriched blobs entrained in a more depleted matrix, or injection of new, more enriched mantle. High 208 Pb/ 204 Pb and moderate 207 Pb/ 204 Pb ratios with respect to Pacific MORB also reflect ancient mantle enrichment. (orig.)

A new perspective on evolution of the Baikal Rift

Directory of Open Access Journals (Sweden)

Victor D. Mats

2011-07-01

The three-stage model of the rift history does not rule out the previous division into two major stages but rather extends its limits back into time as far as the Maastrichtian. Our model is consistent with geological, stratigraphic, structural, and geophysical data and provides further insights into the understanding of rifting in the Baikal region in particular and continental rifting in general.

Analogue modelling of microcontinent formation: a case study from the Danakil Block, southern Red Sea

Science.gov (United States)

Molnar, Nicolas; Cruden, Alexander; Betts, Peter

2017-04-01

The kinematic evolution of the Danakil Block is well constrained but the processes responsible for the formation of an isolated continental segment around 13 Ma ago with an independent pole of rotation are still matter of debate. We performed three-dimensional analogue experiments of rotational continental extension containing a pre-existing linear weakness zones in the lithospheric mantle to investigate the formation of the Red Sea, including the Danakil Block. We imposed a rotational extensional boundary condition that simulates the progressive anticlockwise rotation of the Arabian Plate with respect to the Nubia Plate over the last 13-15 Ma and we simulated the presence of a narrow thermal anomaly related to the northward channelling of Afar plume by varying the viscosity of the model lithospheric mantle. The results from experiments containing a linear zone of weakness oriented at low angles with respect to the rift axis show that early stages of deformation are characterised by the development of two rift sub-parallel compartments that delimit an intra-rift block in the vicinity of the weak lithosphere boundary zone, which are analogous to the two rift branches that confine the Danakil Block in the southern Red Sea. The imposed rotational boundary condition creates a displacement gradient along the intra-rift block and prevents the nucleation of the early rift compartments to the north of the block, enhancing the formation of an independently rotating intra-rift segment. Comparison with geodetic data supports our modelling results, which are also in agreement with the "crank-arm" model of Sichler (1980. La biellette Danakile: un modèle pour l'évolution géodynamique de l'Afar. Bull. la Société Géologique Fr. 22, 925-933). Additional analogue models of i) orthogonal extension with an identical lithospheric mantle weakness and, ii) rotational extension with a homogeneous lithosphere (i.e., no lithospheric mantle weakness) show no evidence of developing

Large-scale variation in lithospheric structure along and across the Kenya rift

Science.gov (United States)

Prodehl, C.; Mechie, J.; Kaminski, W.; Fuchs, K.; Grosse, C.; Hoffmann, H.; Stangl, R.; Stellrecht, R.; Khan, M.A.; Maguire, Peter K.H.; Kirk, W.; Keller, Gordon R.; Githui, A.; Baker, M.; Mooney, W.; Criley, E.; Luetgert, J.; Jacob, B.; Thybo, H.; Demartin, M.; Scarascia, S.; Hirn, A.; Bowman, J.R.; Nyambok, I.; Gaciri, S.; Patel, J.; Dindi, E.; Griffiths, D.H.; King, R.F.; Mussett, A.E.; Braile, L.W.; Thompson, G.; Olsen, K.; Harder, S.; Vees, R.; Gajewski, D.; Schulte, A.; Obel, J.; Mwango, F.; Mukinya, J.; Riaroh, D.

1991-01-01

The Kenya rift is one of the classic examples of a continental rift zone: models for its evolution range from extension of the lithosphere by pure shear1, through extension by simple shear2, to diapiric upwelling of an asthenolith3. Following a pilot study in 19854, the present work involved the shooting of three seismic refraction and wide-angle reflection profiles along the axis, across the margins, and on the northeastern flank of the rift (Fig. 1). These lines were intended to reconcile the different crustal thickness estimates for the northern and southern parts of the rift4-6 and to reveal the structure across the rift, including that beneath the flanks. The data, presented here, reveal significant lateral variations in structure both along and across the rift. The crust thins along the rift axis from 35 km in the south to 20 km in the north; there are abrupt changes in Mono depth and uppermost-mantle seismic velocity across the rift margins, and crustal thickening across the boundary between the Archaean craton and PanAfrican orogenic belt immediately west of the rift. These results suggest that thickened crust may have controlled the rift's location, that there is a decrease in extension from north to south, and that the upper mantle immediately beneath the rift may contain reservoirs of magma generated at greater depth.

Two-phase opening of Andaman Sea: a new seismotectonic insight

Science.gov (United States)

Khan, P. K.; Chakraborty, Partha Pratim

2005-01-01

High-resolution reconstruction of Benioff zone depth-dip angle trajectory for Burma-Java subduction margin between 2° and 17°N Lat. reveals two major episodes of plate geometry change expressed as abrupt deviation in subduction angle. Estimation of effective rate of subduction in different time slices (and then length of subducted slab) allowed drawing of isochrones in Ma interval through these trajectories for the time period 5-12 Ma. With these isochrones, the deformation events on the subducting Indian plate are constrained in time as of 4-5 and 11 Ma old. This well-constrained time connotation offered scope for the correlation of slab deformation events with the well-established two-phase opening history of the Andaman Sea. While the 11 Ma event recorded from southern part of the study area is correlated with early stretching and rifting phase, the 4-5 Ma event is interpreted as major forcing behind the spreading phase of the Andaman Sea. Systematic spatio-temporal evaluation of Indian plate obliquity on the Andaman Sea evolution shows its definite control on the early rifting phase, initiated towards south near northwest Sumatra. The much young spreading phase recorded towards north of 7° Lat. is possibly the result of late Miocene-Pliocene trench retreat and follow-up transcurrent movement (along Sagaing and Sumatran fault system) with NW-SE pull-apart extension. Nonconformity between plate shape and subduction margin geometry is interpreted as the causative force behind Mid-Miocene intraplate extension and tearing. Enhanced stretching in the overriding plate consequently caused active forearc subsidence, recorded all along this plate margin. Initial phase of the Andaman Sea opening presumably remains concealed in this early-middle Miocene forearc subsidence history. The late Miocene-Pliocene pull-apart opening and spreading was possibly initiated near the western part of the Mergui-Sumatra region and propagated northward in subsequent period. A temporary

Planning for Rift Valley fever virus: use of geographical information systems to estimate the human health threat of white-tailed deer (Odocoileus virginianus-related transmission

Directory of Open Access Journals (Sweden)

Sravan Kakani

2010-11-01

Full Text Available Rift Valley fever (RVF virus is a mosquito-borne phlebovirus of the Bunyaviridae family that causes frequent outbreaks of severe animal and human disease in sub-Saharan Africa, Egypt and the Arabian Peninsula. Based on its many known competent vectors, its potential for transmission via aerosolization, and its progressive spread from East Africa to neighbouring regions, RVF is considered a high-priority, emerging health threat for humans, livestock and wildlife in all parts of the world. Introduction of West Nile virus to North America has shown the potential for “exotic” viral pathogens to become embedded in local ecological systems. While RVF is known to infect and amplify within domestic livestock, such as taurine cattle, sheep and goats, if RVF virus is accidentally or intentionally introduced into North America, an important unknown factor will be the role of local wildlife in the maintenance or propagation of virus transmission. We examined the potential impact of RVF transmission via white-tailed deer (Odocoileus virginianus in a typical north-eastern United States urban-suburban landscape, where livestock are rare but where these potentially susceptible, ungulate wildlife are highly abundant. Model results, based on overlap of mosquito, human and projected deer densities, indicate that a significant proportion (497/1186 km2, i.e. 42% of the urban and peri-urban landscape could be affected by RVF transmission during the late summer months. Deer population losses, either by intervention for herd reduction or by RVF-related mortality, would substantially reduce these likely transmission zones to 53.1 km2, i.e. by 89%.

Mantle Flow Across the Baikal Rift Constrained With Integrated Seismic Measurements

Science.gov (United States)

Lebedev, S.; Meier, T.; van der Hilst, R. D.

2005-12-01

The Baikal Rift is located at the boundary of the stable Siberian Craton and deforming central Mongolia. The origin of the late Cenozoic rifting and volcanism are debated, as is the mantle flow beneath the rift zone. Here we combine new evidence from azimuthally-anisotropic upper-mantle tomography and from a radially-anisotropic inversion of interstation surface-wave dispersion curves with previously published shear-wave-splitting measurements of azimuthal anisotropy across the rift (Gao et al. 1994). While our tomographic model maps isotropic and anisotropic shear-velocity heterogeneity globally, the inversion of interstation phase-velocity measurements produces a single, radially-anisotropic, shear-velocity profile that averages from the rift to 500 km SE of it. The precision and the broad band (8-340 s) of the Rayleigh and Love wave curves ensures high accuracy of the profile. Tomography and shear-wave splitting both give a NW-SE fast direction (perpendicular to the rift) in the vicinity of the rift, changing towards W-E a few hundred kilometers from it. Previously, this has been interpreted as evidence for mantle flow similar to that beneath mid-ocean ridges, with deeper vertical flow directly beneath the rift also proposed. Our radially anisotropic profile, however, shows that while strong anisotropy with SH waves faster than SV waves is present in the thin lithosphere and upper asthenosphere beneath and SE of the rift, no anisotropy is required below 110 km. The tomographic model shows thick cratonic lithosphere north of the rift. These observations suggest that instead of a flow diverging from the rift axis in NW and SE directions, the most likely pattern is the asthenospheric flow in SE direction from beneath the Siberian lithosphere and across the rift. Possible driving forces of the flow are large-scale lithospheric deformation in East Asia and the draining of asthenosphere at W-Pacific subduction zones; a plume beneath the Siberian craton also cannot be

Mid Cenozoic freshwater wetlands of the Sunda region

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Robert J. Morley

2013-08-01

Full Text Available The Sunda region was the scene of widespread rifting during the mid-Cenozoic, resulting in the development of numerous large lake-filled rifts, analogous in scale to the rift valley system of East Africa. The Tonle Sap in Cambodia forms the closest modern analogue for these lakes in the Southeast Asian region. Many of the palaeolakes were long lived, continuing uninterrupted as open lakes for several millions of years during the Oligocene. Smaller rift systems infilled with fluvial sediments, but the larger ones remained as lakes, and with Late Oligocene subsidence, were transformed by brackish, and in the earliest Miocene, by marine incursion, into large inland seas. These seas reached their greatest extent at the time of the mid Miocene thermal maximum. This paper describes the development and eventual demise of these lakes following marine transgression, and, based on their rich content of pollen and spores, illustrates the variety of fresh and brackish water swamp communities which developed around their margins. The marginal swamps can be divided into: i seasonally inundated swamps, mainly during the Oligocene, characterised by Barringtonia, Lagerstroemia and grasses/sedges; ii fern swamps and iii from the Late Oligocene onward alluvial swamps, often characterised by Pandanus; and iv peat swamps. The latter can be differentiated into kerapah peat swamps, first occurring during the Oligocene, and basinal peat swamps, becoming widespread from the Early Miocene onward.

Validation of an IgM antibody capture ELISA based on a recombinant nucleoprotein for identification of domestic ruminants infected with Rift Valley fever virus.

Science.gov (United States)

Williams, Roy; Ellis, Charlotte Elizabeth; Smith, Shirley Jacqueline; Potgieter, Christiaan Abraham; Wallace, David; Mareledwane, Vuyokazi Epipodia; Majiwa, Phelix Antipas Ochola

2011-11-01

The presence of competent vectors in some countries currently free of Rift Valley fever (RVF) and global changes in climate, travel and trade have increased the risk of RVF spreading to new regions and have emphasised the need for accurate and reliable diagnostic tools for early diagnosis during RVF outbreaks. Highly sensitive viral detection systems like PCR have a limited use during outbreaks because of the short duration of viraemia, whereas antibodies like specific IgM which are serological indicators of acute infection, can be detected for up to 50 days after infection. Using the highly conserved and immunogenic recombinant nucleoprotein of RVF virus in an IgM capture ELISA, the risk of laboratory infection associated with traditional serological methods is avoided. The use of pre-coated/pre-blocked ELISA plates and the conjugation of the recombinant nucleoprotein with horseradish peroxidase simplified and shortened the assay procedure. Results showed the assay to be highly reproducible with a lower detection limit equal to that of a commercial competition ELISA. By receiver operating characteristic (ROC) curve analysis the area under curve (AUC) index was determined as 1.0 and the diagnostic sensitivity and specificity at a PP cut-off value of 4.1 as 100% and 99.78% respectively. The results of this study demonstrated that the IgM capture ELISA is a safe, reliable and highly accurate diagnostic tool which can be used on its own or in parallel with other methods for the early diagnosis of RVF virus infection and also for monitoring of immune responses in vaccinated domestic ruminants. Copyright © 2011 Elsevier B.V. All rights reserved.

Rescue of infectious rift valley fever virus entirely from cDNA, analysis of virus lacking the NSs gene, and expression of a foreign gene.

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Ikegami, Tetsuro; Won, Sungyong; Peters, C J; Makino, Shinji

2006-03-01

Rift Valley fever virus (RVFV) (genus Phlebovirus, family Bunyaviridae) has a tripartite negative-strand genome, causes a mosquito-borne disease that is endemic in sub-Saharan African countries and that also causes large epidemics among humans and livestock. Furthermore, it is a bioterrorist threat and poses a risk for introduction to other areas. In spite of its danger, neither veterinary nor human vaccines are available. We established a T7 RNA polymerase-driven reverse genetics system to rescue infectious clones of RVFV MP-12 strain entirely from cDNA, the first for any phlebovirus. Expression of viral structural proteins from the protein expression plasmids was not required for virus rescue, whereas NSs protein expression abolished virus rescue. Mutants of MP-12 partially or completely lacking the NSs open reading frame were viable. These NSs deletion mutants replicated efficiently in Vero and 293 cells, but not in MRC-5 cells. In the latter cell line, accumulation of beta interferon mRNA occurred after infection by these NSs deletion mutants, but not after infection by MP-12. The NSs deletion mutants formed larger plaques than MP-12 did in Vero E6 cells and failed to shut off host protein synthesis in Vero cells. An MP-12 mutant carrying a luciferase gene in place of the NSs gene replicated as efficiently as MP-12 did, produced enzymatically active luciferase during replication, and stably retained the luciferase gene after 10 virus passages, representing the first demonstration of foreign gene expression in any bunyavirus. This reverse genetics system can be used to study the molecular virology of RVFV, assess current vaccine candidates, produce new vaccines, and incorporate marker genes into animal vaccines.

Depth to Curie temperature across the central Red Sea from magnetic data using the de-fractal method

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Salem, Ahmed; Green, Chris; Ravat, Dhananjay; Singh, Kumar Hemant; East, Paul; Fairhead, J. Derek; Mogren, Saad; Biegert, Ed

2014-06-01

The central Red Sea rift is considered to be an embryonic ocean. It is characterised by high heat flow, with more than 90% of the heat flow measurements exceeding the world mean and high values extending to the coasts - providing good prospects for geothermal energy resources. In this study, we aim to map the depth to the Curie isotherm (580 °C) in the central Red Sea based on magnetic data. A modified spectral analysis technique, the “de-fractal spectral depth method” is developed and used to estimate the top and bottom boundaries of the magnetised layer. We use a mathematical relationship between the observed power spectrum due to fractal magnetisation and an equivalent random magnetisation power spectrum. The de-fractal approach removes the effect of fractal magnetisation from the observed power spectrum and estimates the parameters of depth to top and depth to bottom of the magnetised layer using iterative forward modelling of the power spectrum. We applied the de-fractal approach to 12 windows of magnetic data along a profile across the central Red Sea from onshore Sudan to onshore Saudi Arabia. The results indicate variable magnetic bottom depths ranging from 8.4 km in the rift axis to about 18.9 km in the marginal areas. Comparison of these depths with published Moho depths, based on seismic refraction constrained 3D inversion of gravity data, showed that the magnetic bottom in the rift area corresponds closely to the Moho, whereas in the margins it is considerably shallower than the Moho. Forward modelling of heat flow data suggests that depth to the Curie isotherm in the centre of the rift is also close to the Moho depth. Thus Curie isotherm depths estimated from magnetic data may well be imaging the depth to the Curie temperature along the whole profile. Geotherms constrained by the interpreted Curie isotherm depths have subsequently been calculated at three points across the rift - indicating the variation in the likely temperature profile with

Dry well analysis of well 6407/10-5 at 793 area, Norwegian Sea.

OpenAIRE

Qamar, Javeria

2017-01-01

Master's thesis in Petroleum Geosciences Engineering. The region of investigation is located in the Norwegian Sea, which is an area of high hydrocarbon activity. Many reservoirs have been successfully identified, drilled, and now they are producing in large oil & gas fields. However, the Norwegian Sea has a complex geology as it resulted from Permian to Late Jurassic crustal extension, which created rift basins and several horst and graben structures. Most of the important hydrocarbon rese...

Blood meal analysis and virus detection in blood-fed mosquitoes collected during the 2006-2007 Rift Valley fever outbreak in Kenya.

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Lutomiah, Joel; Omondi, David; Masiga, Daniel; Mutai, Collins; Mireji, Paul O; Ongus, Juliette; Linthicum, Ken J; Sang, Rosemary

2014-09-01

Rift Valley fever (RVF) is a zoonosis of domestic ruminants in Africa. Blood-fed mosquitoes collected during the 2006-2007 RVF outbreak in Kenya were analyzed to determine the virus infection status and animal source of the blood meals. Blood meals from individual mosquito abdomens were screened for viruses using Vero cells and RT-PCR. DNA was also extracted and the cytochrome c oxidase 1 (CO1) and cytochrome b (cytb) genes amplified by PCR. Purified amplicons were sequenced and queried in GenBank and Barcode of Life Database (BOLD) to identify the putative blood meal sources. The predominant species in Garissa were Aedes ochraceus, (n=561, 76%) and Ae. mcintoshi, (n=176, 24%), and Mansonia uniformis, (n=24, 72.7%) in Baringo. Ae. ochraceus fed on goats (37.6%), cattle (16.4%), donkeys (10.7%), sheep (5.9%), and humans (5.3%). Ae. mcintoshi fed on the same animals in almost equal proportions. RVFV was isolated from Ae. ochraceus that had fed on sheep (4), goats (3), human (1), cattle (1), and unidentified host (1), with infection and dissemination rates of 1.8% (10/561) and 50% (5/10), respectively, and 0.56% (1/176) and 100% (1/1) in Ae. mcintoshi. In Baringo, Ma. uniformis fed on sheep (38%), frogs (13%), duikers (8%), cattle (4%), goats (4%), and unidentified hosts (29%), with infection and dissemination rates of 25% (6/24) and 83.3% (5/6), respectively. Ndumu virus (NDUV) was also isolated from Ae. ochraceus with infection and dissemination rates of 2.3% (13/561) and 76.9% (10/13), and Ae. mcintoshi, 2.8% (5/176) and 80% (4/5), respectively. Ten of the infected Ae. ochraceus had fed on goats, sheep (1), and unidentified hosts (2), and Ae. mcintoshi on goats (3), camel (1), and donkey (1). This study has demonstrated that RVFV and NDUV were concurrently circulating during the outbreak, and sheep and goats were the main amplifiers of these viruses respectively.

Estimation of age of Dali-Ganis rifting and associated volcanic activity, Venus

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Basilevsky, A. T.

1993-01-01

This paper deals with the estimation of age for the Dali and Ganis Chasma rift zones and their associated volcanism based on photogeologic analysis of stratigraphic relations of rift-associated features with impact craters which have associated features indicative of their age. The features are radar-dark and parabolic, and they are believed to be mantles of debris derived from fallout of the craters' ejecta. They are thought to be among the youngest features on the Venusian surface, so their 'parent' craters must also be very young, evidently among the youngest 10 percent of Venus' crater population. Dali Chasma and Ganis Chasma are a part of a system of rift zones contained within eastern Aphrodite and Atla Regio which is a significant component of Venus tectonics. The rifts of this system are fracture belts which dissect typical Venusian plains with rare islands of tessera terrain. The rift zone system consists of several segments following each other (Diane, Dali, Ganis) and forming the major rift zone line, about 10,000 km long, which has junctions with several other rift zones, including Parga Chasma Rift. The junctions are usually locations of rift-associated volcanism in the form of volcanic edifices (Maat and Ozza Montes) or plain-forming flows flooding some areas within the rift zones and the adjacent plains.

Tectonic characteristics and structural styles of a continental rifted basin: Revelation from deep seismic reflection profiles

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Yuan Li

2016-09-01

Full Text Available The Fushan Depression is a half-graben rifted sub-basin located in the southeast of the Beibuwan Basin, South China Sea. The Paleogene Liushagang sequence is the main hydrocarbon-bearing stratigraphic unit in the sub-basin. Using three-dimensional (3-D seismic data and logging data over the sub-basin, we analyzed structural styles and sedimentary characteristics of the Liushagang sequence. Five types of structural styles were defined: ancient horst, traditional slope, flexure slope-break, faulted slope-break and multiple-stage faults slope, and interpretations for positions, background and development formations of each structural style were discussed. Structural framework across the sub-basin reveals that the most remarkable tectonic setting is represented by the central transfer zone (CTZ which divides the sub-basin into two independent depressions, and two kinds of sequence architectures are summarized: (i the western multi-stage faults slope; (ii the eastern flexure slope break belt. Combined with regional stress field of the Fushan Depression, we got plane combinations of the faults, and finally built up plan distribution maps of structural system for main sequence. Also, we discussed the controlling factors mainly focused on subsidence history and background tectonic activities such as volcanic activity and earthquakes. The analysis of structural styles and tectonic evolution provides strong theoretical support for future prospecting in the Fushan sub-basin and other similar rifted basins of the Beibuwan Basin in South China Sea.

Oblique rift opening revealed by reoccurring magma injection in central Iceland

KAUST Repository

Ruch, Joel; Wang, Teng; Xu, Wenbin; Hensch, Martin; Jonsson, Sigurjon

2016-01-01

-field deformation has rarely been captured, hindering progress in understanding rifting mechanisms and evolution. Here we show new evidence of oblique rift opening during a rifting event influenced by pre-existing fractures and two centuries of extension deficit

Images of the East Africa Rift System from the Joint Inversion of Body Waves, Surface Waves, and Gravity: Investigating the Role of Magma in Early-Stage Continental Rifting

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Roecker, S. W.; Ebinger, C. J.; Tiberi, C.; Mulibo, G. D.; Ferdinand-Wambura, R.; Muzuka, A.; Khalfan, M.; Kianji, G.; Gautier, S.; Albaric, J.; Peyrat, S.

2015-12-01

With several rift segments at different stages of the rifting cycle, and the last orogenic episode more than 500 Mya, the young (Ngorongoro caldera appears to be physically cut off from the magma beneath the main part of the rift zone by a relatively thin (< 10 km) wide zone of higher shear wave speeds that lies along the western edge of the fault-bounded rift. The narrow ridge of higher velocity lower crustal material may be a consequence of flexural uplift of the rift flank in response to stretching of strong, cratonic lithosphere.

Zonation of Microbial Communities by a Hydrothermal Mound in the Atlantis II Deep (the Red Sea)

KAUST Repository

Wang, Yong

2015-10-20

In deep-sea geothermal rift zones, the dispersal of hydrothermal fluids of moderately-high temperatures typically forms subseafloor mounds. Major mineral components of the crust covering the mound are barite and metal sulfides. As a result of the continental rifting along the Red Sea, metalliferous sediments accumulate on the seafloor of the Atlantis II Deep. In the present study, a barite crust was identified in a sediment core from the Atlantis II Deep, indicating the formation of a hydrothermal mound at the sampling site. Here, we examined how such a dense barite crust could affect the local environment and the distribution of microbial inhabitants. Our results demonstrate distinctive features of mineral components and microbial communities in the sediment layers separated by the barite crust. Within the mound, archaea accounted for 65% of the community. In contrast, the sediments above the barite boundary were overwhelmed by bacteria. The composition of microbial communities under the mound was similar to that in the sediments of the nearby Discovery Deep and marine cold seeps. This work reveals the zonation of microbial communities after the formation of the hydrothermal mound in the subsurface sediments of the rift basin.

Zonation of Microbial Communities by a Hydrothermal Mound in the Atlantis II Deep (the Red Sea.

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Yong Wang

Full Text Available In deep-sea geothermal rift zones, the dispersal of hydrothermal fluids of moderately-high temperatures typically forms subseafloor mounds. Major mineral components of the crust covering the mound are barite and metal sulfides. As a result of the continental rifting along the Red Sea, metalliferous sediments accumulate on the seafloor of the Atlantis II Deep. In the present study, a barite crust was identified in a sediment core from the Atlantis II Deep, indicating the formation of a hydrothermal mound at the sampling site. Here, we examined how such a dense barite crust could affect the local environment and the distribution of microbial inhabitants. Our results demonstrate distinctive features of mineral components and microbial communities in the sediment layers separated by the barite crust. Within the mound, archaea accounted for 65% of the community. In contrast, the sediments above the barite boundary were overwhelmed by bacteria. The composition of microbial communities under the mound was similar to that in the sediments of the nearby Discovery Deep and marine cold seeps. This work reveals the zonation of microbial communities after the formation of the hydrothermal mound in the subsurface sediments of the rift basin.