WorldWideScience

Sample records for stronger equatorial ligand

  1. Fine-Tuning of Magnetic Properties in Nickel(II) Trinuclear EMACs via Modifications of Equatorial Ligands.

    Science.gov (United States)

    Szarek, P; Grochala, W

    2015-09-03

    The relationship between equatorial ligands structures and magnetic response of [Ni3]6+ extended metal atom chain core has been investigated. The distances between metal ions in Ni metal strings are largely predefined by framework provided through equatorial ligands. The equatorial ligands thus have primary influence on the magnitude of magnetic coupling between terminal high spin centers. Since the σ channel has greatest contribution to J, the variations in Ni–Ni bond lengths have immediate and strong effect on magnetic properties. The secondary, yet important role is played by ligand field strength and nucleophilicity. It has been shown that energy difference between singly occupied σ-type MOs composed of d(z2) of terminal ions and doubly occupied σ-type MO evolved from d(z2) of the central ion in antiferromagnetic state solution is inversely proportional to magnitude of J. Hence, the alignment between energies of d(z2) orbitals on HS and LS centers directly affected by ligand field strength governs the magnetic response. Moreover, the greater basicity of lone pairs coordinating terminal metal atoms correlates with the larger absolute value of magnetic coupling constant.

  2. Stronger synergies

    CERN Document Server

    Antonella Del Rosso

    2012-01-01

    CERN was founded 58 years ago under the auspices of UNESCO. Since then, both organisations have grown to become world leaders in their respective fields. The links between the two have always existed but today they are even stronger, with new projects under way to develop a more efficient way of exchanging information and devise a common strategy on topics of mutual interest.   CERN and UNESCO are a perfect example of natural partners: their common field is science and education is one of the pillars on which both are built. Historically, they share a common heritage. Both UNESCO and CERN were born of the desire to use scientific cooperation to rebuild peace and security in the aftermath of the Second World War. "Recently, building on our common roots and in close collaboration with UNESCO, we have been developing more structured links to ensure the continuity of the actions taken over the years," says Maurizio Bona, who is in charge of CERN relations with international orga...

  3. Equatorial Guinea.

    Science.gov (United States)

    1989-03-01

    Equatorial Guinea is situated on the Gulf of Guinea along the west African coast between Cameroon and Gabon. The people are predominantly of Bantu origin. The country's ties with Spain are significant; in 1959, it became the Spanish Equatorial region ruled by Spain's commissioner general. Recent political developments in Equatorial Guinea include the formation of the Democratic Party for Equatorial Guinea in July of 1987 and the formation of a 60-member unicameral Chamber of Representatives of the People in 1983. Concerning the population, 83% of the people are Catholic and the official language is Spanish. Poverty and serious health, education and sanitary problems exist. There is no adequate hospital and few trained physicians, no dentists, and no opticians. Malaria is endemic and immunization for yellow fever is required for entrance into the country. The water is not potable and many visitors to the country bring bottled water. The tropical climate of Equatorial Guinea provides the climate for the country's largest exports and source of economy; cacao, wood and coffee. Although the country, as a whole, has progressed towards developing a participatory political system, there are still problems of governmental corruption in the face of grave health and welfare conditions. In recent years, the country has received assistance from the World Bank and the United States to aid in its development.

  4. Equatorial Guinea.

    Science.gov (United States)

    1984-06-01

    Attention in this discussion of Equatorial Guinea is directed to the following: the people, history, geography, government, political conditions, the economy, foreign relations, and relations between the US and Equatorial Guinea. The population was estimated at 304,000 in 1983 and the annual growth rate was estimated in the range of 1.7-2.5. The infant mortality rate is 142.9/1000 with a life expectancy of 44.4 years for males and 47.6 years for females. The majority of the Equatoguinean people are of Bantu origin. The largest tribe, the Fang, is indigenous to the mainland, although many now also live on Bioko Island. Portuguese explorers found the island of Bioko in 1471, and the Portuguese retained control until 1778, when the island, adjacent islets, and the commercial rights to the mainland between the Niger and Ogooue Rivers were ceded to Spain. Spain lacked the wealth and the interest to develop an extensive economic infrastructure in Equatorial Guinea during the 1st half of this century, but the Spanish did help Equatorial Guinea achieve 1 of the highest literacy rates in Africa. They also founded a good network of health care facilities. In March 1968, under pressure from Guinean nationalists, Spain announced that it would grant independence to Equatorial Guinea as rapidly as possible. A referendum was held on August 11, 1968, and 63% of the electorate voted in favor of the constitution, which provided for a government with a general assembly and presidentially appointed judges in the Supreme Court. After the coup in August 1979, power was placed in the hands of a Supreme Military Council. A new constitution came into effect after a popular vote in August 1982, abolishing the Supreme Military Council. Under the terms of the constitution, the president was given extensive powers. By the end of 1983, a 60-member Chamber of Representatives of the people had been formed. The government, which is credited with restoring greater personal freedom, is regarded

  5. Intermonsoonal equatorial jets

    Digital Repository Service at National Institute of Oceanography (India)

    Muraleedharan, P.M.

    , respectively. Hydrographic features and transport computations favour a well developed equatorial jet during both seasons. The net surface eastward and subsurface westward flows are well balanced during the premonsoon transition period and appear...

  6. Prospects for stronger calandria tubes

    International Nuclear Information System (INIS)

    Ells, C.E.; Coleman, C.E.; Hosbons, R.R.; Ibrahim, E.F.; Doubt, G.L.

    1990-12-01

    The CANDU calandria tubes, made of seam welded and annealed Zircaloy-2, have given exemplary service in-reactor. Although not designed as a system pressure containment, calandria tubes may remain intact even in the face of pressure tube rupture. One such incident at Pickering Unit 2 demonstrated the economic advantage of such an outcome, and a case can be made for increasing the probability that other calandria tubes would perform in a similar fashion. Various methods of obtaining stronger calandria tubes are available, and reviewed here. When the tubes are internally pressurized, the weld is the weak section of the tube. Increasing the oxygen concentration in the starting sheet, and thickening the weld, are promising routes to a stronger tube

  7. Pacific Equatorial Transect

    OpenAIRE

    Pälike, Heiko; Nishi, Hiroshi; Lyle, Mitch; Raffi, Isabella; Klaus, Adam; Gamage, Kusali

    2009-01-01

    Integrated Ocean Drilling Program Expedition 320/321, "Pacific Equatorial Age Transect" (Sites U1331–U1338), was designed to recover a continuous Cenozoic record of the paleoequatorial Pacific by coring above the paleoposition of the Equator at successive crustal ages on the Pacific plate. These sediments record the evolution of the paleoequatorial climate system throughout the Cenozoic. As we gained more information about the past movement of plates and when in Earth's history "critical" cli...

  8. Equatorial MU Radar project

    Science.gov (United States)

    Yamamoto, Mamoru; Hashiguchi, H.; Tsuda, Toshitaka; Yamamoto, Masayuki

    Research Institute for Sustainable Humanosphere, Kyoto University (RISH) has been studying the atmosphere by using radars. The first big facility was the MU (Middle and Upper atmosphere) radar installed in Shiga, Japan in 1984. This is one of the most powerful and multi-functional radar, and is successful of revealing importance of atmospheric waves for the dynamical vertical coupling processes. The next big radar was the Equatorial Atmosphere Radar (EAR) installed at Kototabang, West Sumatra, Indonesia in 2001. The EAR was operated under close collaboration with LAPAN (Indonesia National Institute for Aeronautics and Space), and conducted the long-term continuous observations of the equatorial atmosphere/ionosphere for more than 10 years. The MU radar and the EAR are both utilized for inter-university and international collaborative research program for long time. National Institute for Polar Research (NIPR) joined EISCAT Scientific Association together with Nagoya University, and developed the PANSY radar at Syowa base in Antarctica as a joint project with University of Tokyo. These are the efforts of radar study of the atmosphere/ionosphere in the polar region. Now we can find that Japan holds a global network of big atmospheric/ionospheric radars. The EAR has the limitation of lower sensitivity compared with the other big radars shown above. RISH now proposes a plan of Equatorial MU Radar (EMU) that is to establish the MU-radar class radar next to the EAR. The EMU will have an active phased array antenna with the 163m diameter and 1055 cross-element Yagis. Total output power of the EMU will be more than 500kW. The EMU can detect turbulent echoes from the mesosphere (60-80km). In the ionosphere incoherent-scatter observations of plasma density, drift, and temperature would be possible. Multi-channel receivers will realize radar-imaging observations. The EMU is one of the key facilities in the project "Study of coupling processes in the solar-terrestrial system

  9. Understanding the Longitudinal Variability of Equatorial Electrodynamics using integrated Ground- and Space-based Observations

    Science.gov (United States)

    Yizengaw, E.; Moldwin, M.; Zesta, E.

    2015-12-01

    The currently funded African Meridian B-Field Education and Research (AMBER) magnetometer array comprises more than thirteen magnetometers stationed globally in the vicinity of geomagnetic equator. One of the main objectives of AMBER network is to understand the longitudinal variability of equatorial electrodynamics as function of local time, magnetic activity, and season. While providing complete meridian observation in the region and filling the largest land-based gap in global magnetometer coverage, the AMBER array addresses two fundamental areas of space physics: first, the processes governing electrodynamics of the equatorial ionosphere as a function of latitude (or L-shell), local time, longitude, magnetic activity, and season, and second, ULF pulsation strength at low/mid-latitude regions and its connection with equatorial electrojet and density fluctuation. The global AMBER network can also be used to augment observations from space-based instruments, such us the triplet SWARM mission and the upcoming ICON missions. Thus, in coordination with space-based and other ground-based observations, the AMBER magnetometer network provides a great opportunity to understand the electrodynamics that governs equatorial ionosphere motions. In this paper we present the longitudinal variability of the equatorial electrodynamics using the combination of instruments onboard SWARM and C/NOFS satellites and ground-based AMBER network. Both ground- and pace-based observations show stronger dayside and evening sector equatorial electrodynamics in the American and Asian sectors compared to the African sector. On the other hand, the African sector is home to stronger and year-round ionospheric bubbles/irregularities compared to the American and Asian sectors. This raises the question if the evening sector equatorial electrodynamics (vertical drift), which is believed to be the main cause for the enhancement of Rayleigh-Taylor (RT) instability growth rate, is stronger in the

  10. Equatorial jet - a case study

    Digital Repository Service at National Institute of Oceanography (India)

    Muraleedharan, P.M.; PrasannaKumar, S.

    and formation of a subsurface high salinity core are, apparently, manifestations of vertical advection of momentum associated with the jet. The driving force behind the equatorial undercurrent in the Indian Ocean ceases to exist in May, causing undercurrent...

  11. Chemical reaction due to stronger Ramachandran interaction

    Indian Academy of Sciences (India)

    The origin of a chemical reaction between two reactant atoms is associated with the activation energy, on the assumption that, high-energy collisions between these atoms, are the ones that overcome the activation energy. Here, we show that a stronger attractive van der Waals (vdW) and electron-ion Coulomb interactions ...

  12. Equatorial zonal circulations: Historical perspectives

    Science.gov (United States)

    Hastenrath, Stefan

    2007-04-01

    The changing perceptions on zonal circulations in the equatorial belt are traced for (a) stratospheric wind regimes, and (b) vertical-zonal circulation cells in the troposphere. (a) Observations from the Krakatoa eruption 1883 and Berson's 1908 expedition to East Africa, along with later soundings over Batavia (Jakarta) led to the notion of "Krakatoa easterlies" around 30 km (10 mb) and "Berson westerlies" around 20 km (50 mb). Prompted by contrary observations since the late 1950s, this dogma was replaced by the notion of easterlies alternating with westerlies in the equatorial stratosphere at a rhythm of about 26 months. (b) Stimulated by Bjerknes' postulate of a "Walker circulation" along the Pacific Equator, a multitude of such cells have been hypothesized at other longitudes, in part from zonal contrasts of temperature and cloudiness. Essential for the diagnosis of equatorial zonal circulation cells is the continuity following the flow between the centers of ascending and subsiding motion. Evaluation of the recent NCEP-NCAR and ECMWF Reanalysis upper-air datasets reveals equatorial zonal circulation cells over the Pacific all year round, over the Atlantic only in boreal winter, and over the Indian Ocean only in autumn, all being seasons and oceanic longitudes with strong zonal flow in the lower troposphere.

  13. Observation of low energy particle precipitation at low altitude in the equatorial zone

    Science.gov (United States)

    Miah, M. A.

    1989-01-01

    Precipitation of protons in the equatorial zone was investigated by the Phoenix-1 experiment on the S81-1 mission from May to November, 1982. The protons show a precipitation peak along the line of minimum magnetic field strength with a FWHM of 13 deg. The index of equatorial pitch angle distribution is about 19. The peak proton flux shows a fifth-power altitude dependence, and the proton flux shows approximately a factor of 3 times increase in 1982 compared to that in 1969 due, possibly, to the stronger solar maximum conditions of 10.7-cm radiation in 1982.

  14. Longitudinal differences of ionospheric vertical density distribution and equatorial electrodynamics

    Science.gov (United States)

    Yizengaw, E.; Zesta, E.; Moldwin, M. B.; Damtie, B.; Mebrahtu, A.; Valladares, C. E.; Pfaff, R. F.

    2012-07-01

    from VEFI onboard Communication/Navigation Outage Forecasting System (C/NOFS) satellite and JULIA radar, is equally promising. The observations at different longitudes suggest that the vertical drift velocities and the vertical density distribution have significant longitudinal differences; especially the equatorial anomaly peaks expand to higher latitudes more in American sector than the African sector, indicating that the vertical drift in the American sector is stronger than the African sector.

  15. LHC Season 2: A stronger machine

    CERN Multimedia

    Dominguez, Daniel

    2015-01-01

    1) New magnets / De nouveaux aimants 2) Stronger connections / Des jonctions électriques renforcées 3) Safer magnets / Des aimants plus sûrs 4) Higher energy beams / Des faisceaux d’énergie plus élevée 5) Narrower beams / Des faisceaux plus serrés 6) Smaller but closer proton packets / Des groupes de protons plus petits mais plus rapprochés 7) Higher voltage / Une tension plus haute 8) Superior cryogenics / Un système cryogénique amélioré 9) Radiation-resistant electronics / Une électronique qui résiste aux radiations 10) More secure vacuum / Un vide plus sûr

  16. Irregularities and Forecast Studies of Equatorial Spread

    Science.gov (United States)

    2016-07-13

    document in the published literature . The result implies that the aeronomy of the postsunset equatorial ionosphere is sufficiently well understood for...of equatorial spread F in the Peruvian sector, J. Geophys. Res. Space Physics, 119, 38153827, doi:10.1002/2014JA019889. ◦ Hysell, D. L., M. A. Milla...L. Condori, and J. W. Meriwether (2014), Data-driven numer- ical simulations of equatorial spread F in the Peruvian sector: 2. Autumnal equinox, J

  17. Gas Marbles: Much Stronger than Liquid Marbles

    Science.gov (United States)

    Timounay, Yousra; Pitois, Olivier; Rouyer, Florence

    2017-06-01

    Enwrapping liquid droplets with hydrophobic particles allows the manufacture of so-called "liquid marbles" [Aussillous and Quéré Nature (London) 411, 924 (2001); , 10.1038/35082026Mahadevan Nature (London)411, 895 (2001), 10.1038/35082164]. The recent intensive research devoted to liquid marbles is justified by their very unusual physical and chemical properties and by their potential for various applications, from microreactors to water storage, including water pollution sensors [Bormashenko Curr. Opin. Colloid Interface Sci. 16, 266 (2011), 10.1016/j.cocis.2010.12.002]. Here we demonstrate that this concept can be successfully applied for encapsulating and protecting small gas pockets within an air environment. Similarly to their liquid counterparts, those new soft-matter objects, that we call "gas marbles," can sustain external forces. We show that gas marbles are surprisingly tenfold stronger than liquid marbles and, more importantly, they can sustain both positive and negative pressure differences. This magnified strength is shown to originate from the strong cohesive nature of the shell. Those interesting properties could be exploited for imprisoning valuable or polluted gases or for designing new aerated materials.

  18. Central Equatorial Pacific Experiment (CEPEX)

    Energy Technology Data Exchange (ETDEWEB)

    1993-01-01

    The Earth's climate has varied significantly in the past, yet climate records reveal that in the tropics, sea surface temperatures seem to have been remarkably stable, varying by less than a few degrees Celsius over geologic time. Today, the large warm pool of the western Pacific shows similar characteristics. Its surface temperature always exceeds 27[degree]C, but never 31[degree]C. Heightened interest in this observation has been stimulated by questions of global climate change and the exploration of stabilizing climate feedback processes. Efforts to understand the observed weak sensitivity of tropical sea surface temperatures to climate forcing has led to a number of competing ideas about the nature of this apparent thermostat. Although there remains disagreement on the processes that regulate tropical sea surface temperature, most agree that further progress in resolving these differences requires comprehensive field observations of three-dimensional water vapor concentrations, solar and infrared radiative fluxes, surface fluxes of heat and water vapor, and cloud microphysical properties. This document describes the Central Equatorial Pacific Experiment (CEPEX) plan to collect such observations over the central equatorial Pacific Ocean during March of 1993.

  19. Quantum cloning machines for equatorial qubits

    International Nuclear Information System (INIS)

    Fan Heng; Matsumoto, Keiji; Wang Xiangbin; Wadati, Miki

    2002-01-01

    Quantum cloning machines for equatorial qubits are studied. For the case of a one to two phase-covariant quantum cloning machine, we present the networks consisting of quantum gates to realize the quantum cloning transformations. The copied equatorial qubits are shown to be separable by using Peres-Horodecki criterion. The optimal one to M phase-covariant quantum cloning transformations are given

  20. The longitudinal variability of equatorial electrojet and vertical drift velocity in the African and American sectors

    OpenAIRE

    E. Yizengaw; M. B. Moldwin; E. Zesta; C. M. Biouele; B. Damtie; A. Mebrahtu; B. Rabiu; C. F. Valladares; R. Stoneback

    2014-01-01

    While the formation of equatorial electrojet (EEJ) and its temporal variation is believed to be fairly well understood, the longitudinal variability at all local times is still unknown. This paper presents a case and statistical study of the longitudinal variability of dayside EEJ for all local times using ground-based observations. We found EEJ is stronger in the west American sector and decreases from west to east longitudinal sectors. We also confirm the presence of signi...

  1. States agree on stronger physical protection regime

    International Nuclear Information System (INIS)

    2005-01-01

    Full text: Delegates from 89 countries agreed on 8 July to fundamental changes that will substantially strengthen the Convention on the Physical Protection of Nuclear Material (CPPNM). IAEA Director General Mohamed ElBaradei welcomed the agreement in saying 'This new and stronger treaty is an important step towards greater nuclear security by combating, preventing, and ultimately punishing those who would engage in nuclear theft, sabotage or even terrorism. It demonstrates that there is indeed a global commitment to remedy weaknesses in our nuclear security regime.' The amended CPPNM makes it legally binding for States Parties to protect nuclear facilities and material in peaceful domestic use, storage as well as transport. It will also provide for expanded cooperation between and among States regarding rapid measures to locate and recover stolen or smuggled nuclear material, mitigate any radiological consequences of sabotage, and prevent and combat related offences. The original CPPNM applied only to nuclear material in international transport. Conference President Dr. Alec Baer said 'All 89 delegations demonstrated real unity of purpose. They put aside some very genuine national concerns in favour of the global interest and the result is a much improved convention that is better suited to addressing the nuclear security challenges we currently face.' The new rules will come into effect once they have been ratified by two-thirds of the 112 States Parties of the Convention, expected to take several years. 'But concrete actions are already taking place around the world. For more than 3 years, the IAEA has been implementing a systematic Nuclear Security plan, including physical protection activities designed to prevent, detect and respond to malicious acts,' said Anita Nillson, Director of the IAEA's Office of Nuclear Security. The Agency's Nuclear Security Fund, set up after the events of 9/11, has delivered $19.5 million in practical assistance to 121 countries

  2. Final Activity Report: The Effects of Iron Complexing Ligands on the Long Term Ecosystem Response to Iron Enrichment of HNLC waters

    Energy Technology Data Exchange (ETDEWEB)

    Trick, Charles Gordon [Western University

    2013-07-30

    Substantial increases in the concentrations of the stronger of two Fe(III) complexing organic ligand classes measured during the mesoscale Fe enrichment studies IronEx II and SOIREE appeared to sharply curtailed Fe availability to diatoms and thus limited the efficiency of carbon sequestration to the deep. Detailed observations during IronEx II (equatorial Pacific Ocean) and SOIREE (Southern Ocean –Pacific sector) indicate that the diatoms began re-experiencing Fe stress even though dissolved Fe concentrations remained elevated in the patch. This surprising outcome likely is related to the observed increased concentrations of strong Fe(III)-complexing ligands in seawater. Preliminary findings from other studies indicate that diatoms may not readily obtain Fe from these chemical species whereas Fe bound by strong ligands appears to support growth of cyanobacteria and nanoflagellates. The difficulty in assessing the likelihood of these changes with in-situ mesoscale experiments is the extended monitoring period needed to capture the long-term trajectory of the carbon cycle. A more detailed understanding of Fe complexing ligand effects on long-term ecosystem structure and carbon cycling is essential to ascertain not only the effect of Fe enrichment on short-term carbon sequestration in the oceans, but also the potential effect of Fe enrichment in modifying ecosystem structure and trajectory.

  3. Final Technical Report: The Effects of Iron Complexing Ligands on the Long Term Ecosystem Response to Iron Enrichment of HNLC waters

    Energy Technology Data Exchange (ETDEWEB)

    Cochlan, William P.

    2008-06-13

    Substantial increases in the concentrations of the stronger of two Fe(III) complexing organic ligand classes measured during the mesoscale Fe enrichment studies IronEx II and SOIREE appeared to sharply curtailed Fe availability to diatoms and thus limited the efficiency of carbon sequestration to the deep. Detailed observations during IronEx II (equatorial Pacific Ocean) and SOIREE (Southern Ocean –Pacific sector) indicate that the diatoms began re-experiencing Fe stress even though dissolved Fe concentrations remained elevated in the patch. This surprising outcome likely is related to the observed increased concentrations of strong Fe(III)-complexing ligands in seawater. Preliminary findings from other studies indicate that diatoms may not readily obtain Fe from these chemical species whereas Fe bound by strong ligands appears to support growth of cyanobacteria and nanoflagellates. The difficulty in assessing the likelihood of these changes with in-situ mesoscale experiments is the extended monitoring period needed to capture the long-term trajectory of the carbon cycle. A more detailed understanding of Fe complexing ligand effects on long-term ecosystem structure and carbon cycling is essential to ascertain not only the effect of Fe enrichment on short-term carbon sequestration in the oceans, but also the potential effect of Fe enrichment in modifying ecosystem structure and trajectory.

  4. The longitudinal variability of equatorial electrojet and vertical drift velocity in the African and American sectors

    Directory of Open Access Journals (Sweden)

    E. Yizengaw

    2014-03-01

    Full Text Available While the formation of equatorial electrojet (EEJ and its temporal variation is believed to be fairly well understood, the longitudinal variability at all local times is still unknown. This paper presents a case and statistical study of the longitudinal variability of dayside EEJ for all local times using ground-based observations. We found EEJ is stronger in the west American sector and decreases from west to east longitudinal sectors. We also confirm the presence of significant longitudinal difference in the dusk sector pre-reversal drift, using the ion velocity meter (IVM instrument onboard the C/NOFS satellite, with stronger pre-reversal drift in the west American sector compared to the African sector. Previous satellite observations have shown that the African sector is home to stronger and year-round ionospheric bubbles/irregularities compared to the American and Asian sectors. This study's results raises the question if the vertical drift, which is believed to be the main cause for the enhancement of Rayleigh–Taylor (RT instability growth rate, is stronger in the American sector and weaker in the African sector – why are the occurrence and amplitude of equatorial irregularities stronger in the African sector?

  5. The longitudinal variability of equatorial electrojet and vertical drift velocity in the African and American sectors

    Science.gov (United States)

    Yizengaw, E.; Moldwin, M. B.; Zesta, E.; Biouele, C. M.; Damtie, B.; Mebrahtu, A.; Rabiu, B.; Valladares, C. F.; Stoneback, R.

    2014-03-01

    While the formation of equatorial electrojet (EEJ) and its temporal variation is believed to be fairly well understood, the longitudinal variability at all local times is still unknown. This paper presents a case and statistical study of the longitudinal variability of dayside EEJ for all local times using ground-based observations. We found EEJ is stronger in the west American sector and decreases from west to east longitudinal sectors. We also confirm the presence of significant longitudinal difference in the dusk sector pre-reversal drift, using the ion velocity meter (IVM) instrument onboard the C/NOFS satellite, with stronger pre-reversal drift in the west American sector compared to the African sector. Previous satellite observations have shown that the African sector is home to stronger and year-round ionospheric bubbles/irregularities compared to the American and Asian sectors. This study's results raises the question if the vertical drift, which is believed to be the main cause for the enhancement of Rayleigh-Taylor (RT) instability growth rate, is stronger in the American sector and weaker in the African sector - why are the occurrence and amplitude of equatorial irregularities stronger in the African sector?

  6. Funnel-shaped, low-frequency equatorial waves

    Science.gov (United States)

    Boardsen, S. A.; Gallagher, D. L.; Gurnett, D. A.; Peterson, W. K.; Green, J. L.

    1992-01-01

    Funnel-shaped, low-frequency radiation, as observed in frequency time spectrograms, is frequently found at the earth's magnetic equator which extends from the proton-cyclotron frequency up to the lower hybrid frequency. Ray-tracing calculations can qualitatively reproduce the observed frequency-time characteristics of these emissions if the waves are propagating in the fast magnetosonic mode starting with wave normal angles of about 88 deg at the magnetic equator. The funnel-shaped emissions are consistent with generation by protons with a ring-type velocity space distribution. A ring-shaped region of positive slope in the velocity space density distribution of protons is observed near the Alfven velocity, indicating that the ring protons strongly interact with the waves. Ray-tracing calculations show that for similar equatorial wave normal angles lower-frequency fast magnetosonic waves are more closely confined to the magnetic equator than higher-frequency fast magnetosonic waves. For waves refracted back toward the equator at similar magnetic latitudes, the lower-frequency waves experience stronger damping in the vicinity of the equator than higher-frequency waves. Also, wave growth is restricted to higher frequencies at larger magnetic latitudes. Wave damping at the equator and wave growth off the equator favors equatorial wave normal angle distributions which lead to the funnel-shaped frequency time characteristic.

  7. Latitudinal comparisons of equatorial Pacific zooplankton

    Science.gov (United States)

    Roman, M. R.; Dam, H. G.; Le Borgne, R.; Zhang, X.

    Zooplankton biomass and rates of ingestion, egestion and production in the equatorial Pacific Ocean along 140°W and 180° exhibit maximum values in the High-Nutrient Low-Chlorophyll (HNLC) zone associated with equatorial upwelling (5°S-5°N) as compared to the more oligotrophic regions to the north and south. Zooplankton biomass and rates are not usually highest on the equator, but increase "downstream" of the upwelling center as the zooplankton populations exhibit a delayed response to enhanced phytoplankton production. The vertical distribution of zooplankton biomass in the equatorial HNLC area tends to be concentrated in surface waters and is more uniform with depth in oligotrophic regions to the north and south of the equatorial upwelling zone. In general, the amount of mesozooplankton (>200 μm) carbon biomass is approximately 25% of estimated phytoplankton biomass and 30% of bacterial biomass in the HNLC area of the equatorial Pacific Ocean. Zooplankton grazing on phytoplankton is low in the equatorial Pacific Ocean, generally migrant zooplankton in the HNLC zone is a minor fraction of the gravitational flux (2% at 140°W, 4% at 180°) but increases in the more oligotrophic regions to the north and south where there is a deeper mixed layer and a greater relative proportion of diel migrant zooplankton.

  8. Stronger Schrödinger-like uncertainty relations

    International Nuclear Information System (INIS)

    Song, Qiu-Cheng; Qiao, Cong-Feng

    2016-01-01

    Highlights: • A stronger Schrödinger-like uncertainty relation in the sum of variances of two observables is obtained. • An improved Schrödinger-like uncertainty relation in the product of variances of two observables is obtained. • A stronger uncertainty relation in the sum of variances of three observables is proposed. - Abstract: Uncertainty relation is one of the fundamental building blocks of quantum theory. Nevertheless, the traditional uncertainty relations do not fully capture the concept of incompatible observables. Here we present a stronger Schrödinger-like uncertainty relation, which is stronger than the relation recently derived by Maccone and Pati (2014) [11]. Furthermore, we give an additive uncertainty relation which holds for three incompatible observables, which is stronger than the relation newly obtained by Kechrimparis and Weigert (2014) [12] and the simple extension of the Schrödinger uncertainty relation.

  9. The oil boom in Equatorial Guinea

    International Nuclear Information System (INIS)

    Frynas, J.G.

    2004-01-01

    In less than a decade, Equatorial Guinea has transformed itself from an African backwater into one of the world's fastest growing economies and a sought-after political partner in the Gulf of Guinea. The sole reason for this transformation has been the discovery of oil and gas. This article outlines the rise of Equatorial Guinea as one of Africa's leading oil-producing countries and investigates the political, economic and social effects of becoming a petro-state. The article is based on the author's field research in Equatorial Guinea in the autumn of 2003 and interviews with senior oil company staff, government officials and staff of international organizations as well as secondary sources. This research demonstrates how reliance on oil and gas exports can lead to profound changes in a country's political economy. (author)

  10. Observation of low energy particle precipitation at low altitude in the equatorial zone

    International Nuclear Information System (INIS)

    Miah, M.A.

    1989-01-01

    Precipitation of protons (∼ 1 MeV) in the equatorial zone was investigated by the Phoenix-1 experiment on board the S81-1 mission from May-November, 1982. The protons show a precipitation peak along the line of minimum magnetic field strength with a full width at half maximum (FWHM) of 13 0 . The index of equatorial pitch angle distribution is q ∼ 19. The peak proton flux shows a fifth-power altitude dependence, and the proton flux shows approximately a factor of 3 times increase in 1982 compared to that in 1969 due, possibly, to the stronger (∼ 1.2 times) solar maximum conditions of 10.7 cm radiation in 1982. (author)

  11. Comparison of storm time equatorial ionospheric electrodynamics in the African and American sectors

    Science.gov (United States)

    Yizengaw, E.; Moldwin, M. B.; Mebrahtu, A.; Damtie, B.; Zesta, E.; Valladares, C. E.; Doherty, P.

    2011-01-01

    The characteristics of storm time (corotating interaction regions (CIR)-driven storm that happened on 9 August 2008) equatorial electrojet (EEJ) phenomena and their effect on the ionospheric density structure at two different longitudinal sectors are presented. Equatorial magnetometer data, occultation density profiles from COSMIC and CHAMP LEO satellites, and ground-based GPS TEC are used. We find unusual density reduction around local noon at the same time when we observe the reversal of electrojet current and thus counter-equatorial electrojet (CEJ) signatures. The continuous energy deposition in to high latitudes due to the CIR-driven storm that triggers the E-region dynamo and the penetrating magnetospheric origin electric field is suggested to be responsible for the reversal of equatorial electrojet current flows. We also compare the magnitude and direction of the driving force (E×B drift) in the American and African sectors for the first time. It was found that at the same local time the E×B drift in the American sector is stronger than that of the African sector. Previously, the uneven distribution of ground-based instruments hindered our ability to obtain a global understanding of the dynamics and structure of the ionosphere. The newly deployed ground-based instruments, primarily in the African sector, provide the opportunity to observe the governing equatorial electrodynamics simultaneously with the ionospheric density structures detected by the instrument onboard low-Earth-orbit (LEO) satellites. To our knowledge this is the first simultaneous observation performed in the African sector. This case study may provide additional input that could be used to explain the unique density irregularities that are often seen from in situ satellite observation in the African sector, a region that has been devoid of ground-based instrumentations.

  12. Coccolithophores in the equatorial Atlantic Ocean

    DEFF Research Database (Denmark)

    Kinkel, Hanno; Baumann, K.-H.; Cepek, M.

    2000-01-01

    The present study was initiated to ascertain the significance of coccolithophores as a proxy for paleoceanographic and paleoproductivity studies in the equatorial Atlantic. Data from a range of different samples, from the plankton, surface sediments as well as sediment cores are shown and compare...

  13. Coccolithophores in the equatorial Atlantic Ocean

    DEFF Research Database (Denmark)

    Kinkel, Hanno; Baumann, K.-H.; Cepek, M.

    2000-01-01

    tenuis are strongly diminished, causing an increase in relative abundance of the lower photic zone taxa Florisphaera profunda and Gladiolithus flabellatus. During the past 140,000 years the surface water circulation of the equatorial Atlantic has changed drastically, as can be seen from changes...

  14. Equatorial electrojet in east Brazil longitudes

    Indian Academy of Sciences (India)

    and West Africa. It is felt that a systematic study of the geomagnetic/ionospheric observations at suit- able sites in Brazil is important to understand EEJ and aspects of space weather. Acknowledgements. The data from the Kyushu network of equatorial electrojet stations is acknowledged. Rastogi and. Chandra are thankful ...

  15. Equatorial electrojet in the Indian region during the geomagnetic ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Earth System Science; Volume 125; Issue 3. Equatorial electrojet in the Indian region ... A strong (–50 nT) and a long duration counterelectrojet, right from 08 to 13 hr on 14 November 1998 was observed resulting in the absence of equatorialEs at Thumba. Absence of the equatorial ionization ...

  16. The Longitudinal Variation of Equatorial Electrodynamics Observations

    Science.gov (United States)

    Yizengaw, E.; Zesta, E.; Moldwin, M.; Valladares, C. E.; Damtie, B.; Mebrahtu, A.; Biouele, C. M.; Yumoto, K.; Pfaff, R. F.; Heelis, R. A.

    2010-12-01

    The uneven distribution of ground-based instruments due to the large ocean coverage in the equatorial regions hinders our ability to obtain a global understanding of the dynamics and structure of the equatorial ionosphere. In Africa, which has been mostly devoid of ground-based instruments, the ionospheric density structure has been traditionally estimated by model interpolation over vast geographic areas. Recent ground- and space-based observations have shown that geomagnetic storms can have dramatic longitudinal differences in equatorial ionospheric electrodynamics, such as enhanced generation of F-region plasma irregularities, and super fountain effect at low latitudes. For example, satellite observations have shown very unique equatorial ionospheric density structures in the African region. The African region is the longitude sector where the occurrence of large scale bubble activity (zonal width, depletion level, and spacing) peaks. No other region in the globe shows similar characteristics. One of the possible driving mechanisms that govern the equatorial electrodynamics is the vertical ExB drift, which strongly affects the structure and dynamics of the ionosphere in the low/mid-latitude region. According to the observations performed at different longitudes, using recently deployed limited ground-based instruments, the vertical ExB drift has significant longitudinal differences. This paper presents initial results of vertical ExB drifts observed at three different longitudes: East African, West African, and West American sectors. The drift is estimated using a pairs of ground-based magnetometers technique. In the African sector stations from the AMBER, INTERMAGNET, and MAGDAS, and in the American sector SAMBA and LISN magnetometer arrays have been used for this study. Finally, the comparison between the magnetometer estimated ExB drift and the vertical drift observations (VEFI and IVM) on board C/NOFS satellites have also been performed, showing promising

  17. Equatorial Electrojet Observations in the African Continent

    Science.gov (United States)

    Yizengaw, E.; Moldwin, M. B.; Mebrahtu, A.; Damtie, B.; Pfaff, R.; Zesta, E.

    2008-12-01

    Although Satellite observations in the African sector show unique equatorial ionospheric structures that can severely impact navigation and communication systems, the study of ionospheric disturbances in this region is difficult due to the lack of ground-based instruments. This has created a gap in global understanding of the physics behind the evolution and formation of plasma irregularities in the equatorial region, which imposes limitations on ionospheric density modeling efforts. Therefore, in order to have a more complete global understanding of equatorial ionosphere motion, the international space science community has begun to develop an observational infrastructure in the African sector. This includes the deployment of a number of arrays of small instruments, including the AMBER magnetometer array, through the International Heliophysical Year (IHY) cooperative program with the United Nations Basic Space Science (UNBSS) program. Two AMBER magnetometers have been deployed successfully at Adigrat (~6°N magnetic) in Ethiopia and at Medea in Algeria (28°N magnetic), and became fully operational on 03 August 2008. The remaining two AMBER magnetometers will be deployed soon in Cameroon and Namibia. One of the prime scientific objectives of AMBER is to understand the processes governing electrodynamics of the equatorial ionosphere as a function of latitude, local time, magnetic activity, and season in the African region. The most credible driving mechanism of ionospheric plasma (E × B drift) can be estimated using two magnetometers, one right at the equator and the other about 6 off the equator. Therefore, using the AMBER magnetometer at Adigrat and the INTERMAGNET magnetometer located at Addis Ababa (0.9°N magnetic) in Ethiopia, the equatorial electrojet (E × B drift) activities in that longitudinal sector of the African continent is estimated. The paper also presents the comparison between the estimated vertical drift and the drift values obtained from the

  18. Equatorial ionospheric electrodynamics during solar flares

    Science.gov (United States)

    Zhang, Ruilong; Liu, Libo; Le, Huijun; Chen, Yiding

    2017-05-01

    Previous investigations on ionospheric responses to solar flares focused mainly on the photoionization caused by the increased X-rays and extreme ultraviolet irradiance. However, little attention was paid to the related electrodynamics. In this letter, we explored the equatorial electric field (EEF) and electrojet (EEJ) in the ionosphere at Jicamarca during flares from 1998 to 2008. It is verified that solar flares increase dayside eastward EEJ but decrease dayside eastward EEF, revealing a negative correlation between EEJ and EEF. The decreased EEF weakens the equatorial fountain effect and depresses the low-latitude electron density. During flares, the enhancement in the Cowling conductivity may modulate ionospheric dynamo and decrease the EEF. Besides, the decreased EEF is closely related to the enhanced ASY-H index that qualitatively reflects Region 2 field-aligned current (R2 FAC). We speculated that solar flares may also decrease EEF through enhancing R2 FAC that leads to an overshielding-like effect.

  19. Wintertime Phytoplankton Blooms in the Western Equatorial Indian Ocean Associated With the Madden-Julian Oscillation

    Science.gov (United States)

    Liao, Xiaomei; Du, Yan; Zhan, Haigang; Wang, Tianyu; Feng, Ming

    2017-12-01

    This study investigated boreal wintertime phytoplankton blooms in the western equatorial Indian Ocean (WEIO) and the underlying physical mechanisms. The Sea viewing Wide field of View sensor (SeaWiFS) chlorophyll-a (Chla) concentrations show that phytoplankton blooms occur in the WEIO during December-March. The development of these blooms is not only a seasonal process but also consists of 2-3 intraseasonal events induced by the Madden-Julian Oscillation (MJO). During a typical intraseasonal event, enhanced cross-equatorial wind induces strong upwelling and ocean mixing, thus increasing the supply of nutrients to the surface in equatorial regions. Argo profiles clearly show various responses to the intraseasonal wind bursts, including shoaling of the thermocline and deepening of the mixed layer. Further analysis reveals that the former is the dominant mechanism for the blooms along the equator, while the latter controls the high Chla concentrations off the coast of Somalia. Surface ocean circulations not only account for the blooms south of the equator but also modulate the thermocline depth in the WEIO. The shallower thermocline during the early period of the northeast monsoon season provides favorable conditions for a stronger Chla response to intraseasonal forcing.

  20. Equatorial Kelvin waves do not vanish

    Science.gov (United States)

    O'Brien, James J.; Parham, Fred

    1992-01-01

    In the last several years many scientists have been using poorly resolved coupled models to study the ENSO. It has been very common to state that an ENSO cycle found in a model cannot have oceanic Kelvin waves as a mechanism because such waves do not exist in an ocean model with coarse grid spaing. In this note it is demonstrated that equatorial Kelvin waves can exist in models with coarse grids.

  1. Seasonal Cycle of Cross Equatorial Flow in the Central Equatorial Indian Ocean

    Science.gov (United States)

    McPhaden, Michael; Wang, Yi

    2017-04-01

    This study investigates the seasonal cycle of meridional currents in the upper layers of central equatorial Indian Ocean using acoustic Doppler current profiler (ADCP) data and other data sets along 80.5°E for the period 2004-13. The ADCP data set is the most comprehensive collection of direct velocity measurements in the central Indian Ocean to date, providing new insights into cross equatorial flow in this region. Mean meridional currents are characterized by subsurface divergence between 50-100 m depths with relatively weak convergence above, driven by the annual mean westward pressure gradient force and the surface westerly wind stress respectively. However, in response to a mean northward component of the surface wind stress, the maximum mean surface layer convergence is shifted off the equator to 0.75°N. Evidence is also presented for the existence of a shallow equatorial roll, consisting of a northward wind-driven surface drift overlaying a southward subsurface flow. Cross equatorial transports during boreal summer and winter indicate that a quasi-steady Sverdrup transport balance dominates the seasonal cycle of upper-layer meridional currents. In addition, semi-annually varying westerly monsoon transition winds force Ekman convergence in the surface layer and set up transient zonal pressure gradients that drive seasonally enhanced meridional geostrophic divergence in the thermocline. These results quantify expectations from ocean circulation theories for equatorial Indian Ocean meridional circulation patterns with a high degree of confidence given the length of the data records.

  2. Women's political participation leads to stronger local economies ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Edgard Rodriguez - IDRC. Women attend a self-help group meeting near Hyderabad, India. Keenara Khanderia. Under changes to India's constitution, Indian women are gaining a stronger political voice. Legal reforms are encouraging women to contribute to economic growth and investments in community growth.

  3. A Stronger Reason for the Right to Sign Languages

    Science.gov (United States)

    Trovato, Sara

    2013-01-01

    Is the right to sign language only the right to a minority language? Holding a capability (not a disability) approach, and building on the psycholinguistic literature on sign language acquisition, I make the point that this right is of a stronger nature, since only sign languages can guarantee that each deaf child will properly develop the…

  4. Equatorial westward electrojet impacting equatorial ionization anomaly development during the 6 April 2000 superstorm

    Science.gov (United States)

    Horvath, Ildiko; Lovell, Brian C.

    2013-11-01

    investigate the forward plasma fountain and the equatorial ionosphere in the topside region during the 6 April 2000 superstorm in the Australian sector at ~0900 LT. Space- and ground-based multi-instrument measurements, Coupled Thermosphere-Ionosphere-Plasmasphere Electrodynamics (CTIPe) simulations, and field-aligned observations comprise our results. These reveal an unusual storm development during which the eastward prompt penetration electric (E) field (PPEF) developed and operated under the continuous effects of the westward disturbance dynamo E-field (DDEF) while large-scale traveling ionospheric disturbances (TIDs) traveled equatorward and generated strong equatorward wind surges. We have identified the eastward PPEF by the superfountain effect causing the equatorial ionization anomaly (EIA)'s development with crests situated at ~±28°N (geomagnetic) in the topside ionosphere at ~840 km altitude. The westward DDEF's occurrence is confirmed by mapping the "anti-Sq" current system wherein the equatorial westward current created a weak long-lasting westward electrojet event. Line plots of vertical drift data tracked large-scale TIDs. Four scenarios, covering ~3.5 h in universal time, demonstrate that the westward DDEF became superimposed on the eastward PPEF. As these E-fields of different origins became mapped into the F region, they could interact. Consequently, the eastward PPEF-related equatorial upward E × B drift became locally reduced by up to 75 m/s near the dip equator by the westward DDEF-related equatorial downward E × B drift. Meanwhile, the EIA displayed a better development as equatorial wind surges, reproduced by CTIPe, increased from 501 to 629 m/s, demonstrating the crucial role of mechanical wind effects keeping plasma density high.

  5. Strong post-midnight Equatorial Ionospheric Anomaly and Equatorial spread F Observations during magnetically quiet period

    Science.gov (United States)

    Moldwin, M. B.; Yizengaw, E.; Sahai, Y.

    2008-12-01

    Post sunset equatorial ionospheric irregularities, especially during magnetically active periods, have been a subject of many studies. The most prominent irregularities often observed right after sunset are the resurgence of the equatorial ionospheric anomaly (EIA) and equatorial spread F (ESF). It is well understood and documented that pre-reversal enhancement, due to the ionospheric conductivity gradient at the dusk, is one of the prime triggering mechanisms for the post-sunset irregularities in the equatorial region. However, less attention has been given to the equatorial irregularities (EIA and ESF) that often occur in post-midnight, especially during magnetically quiet periods. It has been suggested that the primary process responsible for the dramatic post-midnight ESF during magnetically active periods is the change in magnitude and direction of the usual equatorial electric field. Earlier studies speculated that during magnetically active post-midnight periods the change in electric field direction from westward to eastward for a short intervals cause an upward E × B drift, resulting in increased h'F and decreased electron densities at the magnetic equator. Individual scans of Jicamarca vertical drift also often observe significant upward drift during post-midnight periods. We present a case of post-midnight strong equatorial ionospheric anomaly during a magnetically quiet (Kp < 3) period using TOPEX altimeter TEC data. Simultaneously, the ionosonde station at S.J. Campos (23.2°S, 45.9°W; dip lat. 17.6°S) observed strong ESF and unusual h'F height rise during post-midnight period, where TOPEX detected strong EIA. At the same time ROCSAT-1 and DMSP satellites also clearly show existence of EIA during post-midnight period at their orbiting altitude. The former satellite also detected post-midnight in situ density irregularities (such as bubbles) at the same time as strong EIA and ESF. The questions here are what triggers these post-midnight equatorial

  6. Role of the Interannual equatorial Kelvin wave propagations in the equatorial Atlantic on the Angola Benguela current system.

    Science.gov (United States)

    Anicet Imbol Koungue, Rodrigue; Illig, Serena; Rouault, Mathieu

    2017-04-01

    The link between equatorial Atlantic Ocean variability and the coastal region of Angola and Namibia is investigated at interannual time scales from 1998 to 2012. An index of the equatorial Kelvin wave activity is defined based on equatorial PIRATA in situ data. Results show a significant correlation between monthly dynamic height anomalies derived from the Prediction and Research Moored Array in the Tropical Atlantic (PIRATA), monthly Sea Surface Height anomalies (SSHA) derived from altimetry and SSHA calculated with an Ocean Linear Model. This allows interpreting PIRATA record into equatorial Kelvin wave signal. Estimated phase speed of eastward propagations from PIRATA equatorial mooring remains in agreement with the linear theory, emphasizing the dominance of the second baroclinic mode. Systematic analysis of all strong interannual equatorial SSH anomalies shows that they precede by one month extreme interannual SST anomalies along the African coast, suggesting that major warm and cold events in the Angola-Benguela current system are remotely forced by ocean atmosphere interactions in the equatorial Atlantic. Wave dynamics along the equatorial wave guide, as inferred from the Ocean Linear Model, is at the origin of their developments. Wind anomalies in the Western Equatorial Atlantic force equatorial downwelling and upwelling Kelvin waves that propagate eastward along the equator and then polewards along the African coast triggering extreme warm and cold events respectively. A proxy index based on linear ocean dynamics appears to be significantly more skilful in forecasting coastal variability than an index based on wind variability.

  7. The equatorial F-layer: progress and puzzles

    Directory of Open Access Journals (Sweden)

    H. Rishbeth

    Full Text Available This work reviews some aspects of the ionospheric F-layer in the vicinity of the geomagnetic equator. Starting with a historical introduction, brief summaries are given of the physics that makes the equatorial ionosphere so interesting, concentrating on the large-scale structure rather than the smaller-scale instability phenomena. Several individual topics are then discussed, including eclipse effects, the asymmetries of the `equatorial trough', variations with longitude, the semiannual variation, the effects of the global thermospheric circulation, and finally the equatorial neutral thermosphere, including `superrotation' and possible topographic influences.

    Keyword: Ionosphere (equatorial ionosphere

  8. Equatorial Oscillations in Jupiter's and Saturn's Atmospheres

    Science.gov (United States)

    Flasar, F. Michael; Guerlet, S.; Fouchet, T.; Schinder, P. J.

    2011-01-01

    Equatorial oscillations in the zonal-mean temperatures and zonal winds have been well documented in Earth's middle atmosphere. A growing body of evidence from ground-based and Cassini spacecraft observations indicates that such phenomena also occur in the stratospheres of Jupiter and Saturn. Earth-based midinfrared measurements spanning several decades have established that the equatorial stratospheric temperatures on Jupiter vary with a cycle of 4-5 years and on Saturn with a cycle of approximately 15 years. Spectra obtained by the Composite Infrared Spectrometer (CIRS) during the Cassini swingby at the end of 2000, with much better vertical resolution than the ground-based data, indicated a series of vertically stacked warm and cold anomalics at Jupiter's equator; a similar structurc was seen at Saturn's equator in CIRS limb measurements made in 2005, in the early phase of Cassini's orbital tour. The thermal wind equation implied similar patterns of mean zonal winds increasing and decreasing with altitude. On Saturn the peak-to-pcak amplitude of this variation was nearly 200 meters per second. The alternating vertical pattern of wanner and colder cquatorial tcmperatures and easterly and westerly tendencies of the zonal winds is seen in Earth's equatorial oscillations, where the pattern descends with time, The Cassini Jupiter and early Saturn observations were snapshots within a limited time interval, and they did not show the temporal evolution of the spatial patterns. However, more recent Saturn observations by CIRS (2010) and Cassini radio-occultation soundings (2009-2010) have provided an opportunity to follow the change of the temperature-zonal wind pattern, and they suggest there is descent, at a rate of roughly one scale height over four years. On Earth, the observed descent in the zonal-mean structure is associated with the absorption of a combination of vertically propagating waves with easlerly and westerly phase velocities. The peak-to-peak zonal wind

  9. Central Equatorial Pacific Experiment (CEPEX). Design document

    Energy Technology Data Exchange (ETDEWEB)

    1993-04-01

    The Earth`s climate has varied significantly in the past, yet climate records reveal that in the tropics, sea surface temperatures seem to have been remarkably stable, varying by less than a few degrees Celsius over geologic time. Today, the large warm pool of the western Pacific shows similar characteristics. Its surface temperature always exceeds 27{degree}C, but never 31{degree}C. Heightened interest in this observation has been stimulated by questions of global climate change and the exploration of stabilizing climate feedback processes. Efforts to understand the observed weak sensitivity of tropical sea surface temperatures to climate forcing has led to a number of competing ideas about the nature of this apparent thermostat. Although there remains disagreement on the processes that regulate tropical sea surface temperature, most agree that further progress in resolving these differences requires comprehensive field observations of three-dimensional water vapor concentrations, solar and infrared radiative fluxes, surface fluxes of heat and water vapor, and cloud microphysical properties. This document describes the Central Equatorial Pacific Experiment (CEPEX) plan to collect such observations over the central equatorial Pacific Ocean during March of 1993.

  10. Fading of Jupiter's South Equatorial Belt

    Science.gov (United States)

    Sola, Michael A.; Orton, Glenn; Baines, Kevin; Yanamandra-Fisher, Padma

    2011-01-01

    One of Jupiter's most dominant features, the South Equatorial Belt, has historically gone through a "fading" cycle. The usual dark, brownish clouds turn white, and after a period of time, the region returns to its normal color. Understanding this phenomenon, the latest occurring in 2010, will increase our knowledge of planetary atmospheres. Using the near infrared camera, NSFCAM2, at NASA's Infrared Telescope Facility in Hawaii, images were taken of Jupiter accompanied by data describing the circumstances of each observation. These images are then processed and reduced through an IDL program. By scanning the central meridian of the planet, graphs were produced plotting the average values across the central meridian, which are used to find variations in the region of interest. Calculations using Albert4, a FORTRAN program that calculates the upwelling reflected sunlight from a designated cloud model, can be used to determine the effects of a model atmosphere due to various absorption, scattering, and emission processes. Spectra that were produced show ammonia bands in the South Equatorial Belt. So far, we can deduce from this information that an upwelling of ammonia particles caused a cloud layer to cover up the region. Further investigations using Albert4 and other models will help us to constrain better the chemical make up of the cloud and its location in the atmosphere.

  11. Observational features of equatorial coronal hole jets

    Directory of Open Access Journals (Sweden)

    G. Nisticò

    2010-03-01

    Full Text Available Collimated ejections of plasma called "coronal hole jets" are commonly observed in polar coronal holes. However, such coronal jets are not only a specific features of polar coronal holes but they can also be found in coronal holes appearing at lower heliographic latitudes. In this paper we present some observations of "equatorial coronal hole jets" made up with data provided by the STEREO/SECCHI instruments during a period comprising March 2007 and December 2007. The jet events are selected by requiring at least some visibility in both COR1 and EUVI instruments. We report 15 jet events, and we discuss their main features. For one event, the uplift velocity has been determined as about 200 km s−1, while the deceleration rate appears to be about 0.11 km s−2, less than solar gravity. The average jet visibility time is about 30 min, consistent with jet observed in polar regions. On the basis of the present dataset, we provisionally conclude that there are not substantial physical differences between polar and equatorial coronal hole jets.

  12. Preliminary report: STOIC CGCM intercomparison - equatorial sections

    International Nuclear Information System (INIS)

    Davey, M; Huddleston, M; Sperber, K R.

    1999-01-01

    An intercomparison and assessment of the tropical behaviour of coupled general circulation models (CGCMs) is being carried out, to identify common strengths and weaknesses and thus guide future CGCM development. The work is being carried out as part of the CLIVAR climate research programme, as a WG-SIP (Working Group on Seasonal to Interannual Prediction) project called STOIC (Study of Tropical Oceans In CGCMs), organised by Michael Davey. This project complements a companion sub-project called ENSIP (El Ni no Simulation Intercomparison Project) organised by Mojib Latif (Max- Planck-Institute for Meteorology) that focusses on equatorial Pacific CGCM behaviour (Latif et al. 1999). Previous coupled model assessments (Mechoso et al. 1995, Neelin et al. 1992, and ENSIP) have focussed on tropical Pacific behaviour. The aim of STOIC is to look at model performance in all tropical ocean regions. This status report contains a sample of the STOIC assessment work, highlighting mean and inter- annual equatorial sea surface temperatures and zonal windstresses. The intention is to submit STOIC and ENSIP papers in mid-1999 for publication together in a refereed journal

  13. Stronger declines in youth alcohol consumption thanks to stronger integrated alcohol policies? A qualitative comparison of ten Dutch municipalities.

    Science.gov (United States)

    de Goeij, Moniek C M; Harting, Janneke; Kunst, Anton E

    2017-03-02

    Little detailed evidence is available on how integrated policies could impact population health and under what conditions such policies could be realized. The aim of this study was to assess how youth alcohol consumption trends in the province of Noord-Brabant, The Netherlands, were related to the development and implementation of integrated policies. In a retrospective multiple case study, alcohol policies of six municipalities with stronger declines in youth alcohol consumption between 2007 and 2011 (cases) were compared to four municipalities with weaker declines (controls). Information on the policy process in the same period was obtained through semi-structured in-depth interviews with policy advisors. Information on implemented interventions was extracted from policy documents and checked by the interviewees. Interviews were analyzed for thematic content. Only municipalities with stronger declines in alcohol consumption involved sectors other than public health and had started to implement interventions that use regulatory or enforcement strategies. Their involvement was facilitated by framing youth alcohol consumption as a safety rather than a health problem, whereby local media played a substantial role. Implementation of integrated policies was further facilitated by dedicated leadership and sufficient resources. Reductions in youth alcohol consumption in Noord-Brabant were stronger when municipalities started to develop integrated policies. Results suggest that integrated policies framing a health problem as a broader societal problem could positively influence population health.

  14. Equatorial counter electrojets and polar stratospheric sudden warmings – a classical example of high latitude-low latitude coupling?

    Directory of Open Access Journals (Sweden)

    C. Vineeth

    2009-08-01

    Full Text Available Favored occurrences of Equatorial Counter Electrojets (CEJs with a quasi 16-day periodicity over Trivandrum (8.5° N, 76.5° E, 0.5° N diplat. in association with the polar Stratospheric Sudden Warming (SSW events are presented. It is observed that, the stratospheric temperature at ~30 km over Trivandrum shows a sudden cooling prior to the SSWs and the CEJs of maximum intensity which occurs around this time. In general stronger CEJs are associated with more intense SSW events. The stratospheric zonal mean zonal wind over Trivandrum also exhibits a distinctly different pattern during the SSW period. These circulation changes are proposed to be conducive for the upward propagation of the lower atmospheric waves over the equatorial latitudes. The interaction of such waves with the tidal components at the upper mesosphere and its subsequent modification are suggested to be responsible for the occurrence of CEJs having planetary wave periods.

  15. Synthesis and transition metal coordination chemistry of a novel hexadentate bispidine ligand.

    Science.gov (United States)

    Comba, Peter; Rudolf, Henning; Wadepohl, Hubert

    2015-02-14

    Reported is the new bispidine-derived hexadentate ligand (L = 3-(2-methylpyridyl)-7-(bis-2-methylpyridyl)-3,7-diazabicyclo[3.3.1]nonane) with two tertiary amine and four pyridine donor groups. This ligand can form heterodinuclear and mononuclear complexes and, in the mononuclear compounds discussed here, the ligand may coordinate as a pentadentate ligand, with one of the bispyridinemethane-based pyridine groups un- or semi-coordinated, or as a hexadentate ligand, leading to a pentagonal pyramidal coordination geometry or, with an additional monodentate ligand, to a heptacoordinate pentagonal bipyramidal structure. The solution and solid state data presented here indicate that, with the relatively small Cu(II) and high-spin Fe(II) ions the fourth pyridine group is only semi-coordinated for steric reasons and, with the larger high-spin Mn(II) ion genuine heptacoordination is observed but with a relatively large distortion in the pentagonal equatorial plane.

  16. The right of the stronger: The play Sisyphus and critias

    Directory of Open Access Journals (Sweden)

    Jordović Ivan

    2004-01-01

    Full Text Available The Focus of this study is the standpoint of the play Sisyphus and critias the leader of the thirty towards the right of the stronger. this is a question of constant interest in scientific circles, since its answer can serve as the indicator of the influence this famous theory has had. this interest has been encouraged by the fact that critias’ authorship of the play is questionable. however, the question of the author is not of primary importance for this article, because there are some arguments, among some well known ones, which were not considered and which Show that in this satire, regardless of the author and the purpose of this fragment, the right of the stronger is actually non-existant. the first argument to support this theory is that nomosphysis antithesis is nowhere explicitly mentioned although it is the crucial element of the right of the stronger. in addition there is no claim in the play that the exploitation of the strong by the week or by law accrued. the second argument is that despite the incapability of laws to prevent the secret injustice, they and their importance for the human society are depicted in a positive light. it should also be noted that, unlike callicles and glaucon, laws are created to stop the bad and not the good. the third argument is that the invention of religion is accepted as a positive achievement, which finally enables the overcoming of primeval times and lawlessness. the reflection of this argument is a positive characterization of the individual who invented the fear of gods. the fourth argument, which has not been taken into consideration so far is the way the supporters and opponents of lawlessness are described and marked as κακοί and έσξλοί in the satire only physically strong are considered as strong as opposed to callicles, where they are also spiritually superior. intelectually superior in Sisyphus is the inventor of the fear of gods who is also in favor of law and order. the fact

  17. Stronger misdirection in curved than in straight motion

    Directory of Open Access Journals (Sweden)

    Jorge eOtero-Millan

    2011-11-01

    Full Text Available Illusions developed by magicians are a rich and largely untapped source of insight into perception and cognition. Here we show that curved motion, as employed by the magician in a classic sleight of hand trick, generates stronger misdirection than rectilinear motion, and that this difference can be explained by the differential engagement of the smooth pursuit and the saccadic oculomotor systems. This research moreover exemplifies how the magician’s intuitive understanding of the spectator’s mindset can surpass that of the cognitive scientist in specific instances, and that observation-based behavioral insights developed by magicians are worthy of quantitative investigation in the neuroscience laboratory.

  18. Evidence of Late Palaeocene-Early Eocene equatorial rain forest ...

    Indian Academy of Sciences (India)

    2009-11-02

    Nov 2, 2009 ... Prevalence of excessive humid climate during this period has been seen as a result of equatorial positioning of Indian subcontinent, superimposed by a long term global warming phase (PETM and EECO) during the early Palaeogene. The study presents clear evidence that highly diversified equatorial rain ...

  19. KIR2DL2/2DL3-E35 alleles are functionally stronger than -Q35 alleles

    Science.gov (United States)

    Bari, Rafijul; Thapa, Rajoo; Bao, Ju; Li, Ying; Zheng, Jie; Leung, Wing

    2016-03-01

    KIR2DL2 and KIR2DL3 segregate as alleles of a single locus in the centromeric motif of the killer cell immunoglobulin-like receptor (KIR) gene family. Although KIR2DL2/L3 polymorphism is known to be associated with many human diseases and is an important factor for donor selection in allogeneic hematopoietic stem cell transplantation, the molecular determinant of functional diversity among various alleles is unclear. In this study we found that KIR2DL2/L3 with glutamic acid at position 35 (E35) are functionally stronger than those with glutamine at the same position (Q35). Cytotoxicity assay showed that NK cells from HLA-C1 positive donors with KIR2DL2/L3-E35 could kill more target cells lacking their ligands than NK cells with the weaker -Q35 alleles, indicating better licensing of KIR2DL2/L3+ NK cells with the stronger alleles. Molecular modeling analysis reveals that the glutamic acid, which is negatively charged, interacts with positively charged histidine located at position 55, thereby stabilizing KIR2DL2/L3 dimer and reducing entropy loss when KIR2DL2/3 binds to HLA-C ligand. The results of this study will be important for future studies of KIR2DL2/L3-associated diseases as well as for donor selection in allogeneic stem cell transplantation.

  20. Proton flux under radiation belts: near-equatorial zone

    International Nuclear Information System (INIS)

    Grigoryan, O.R.; Panasyuk, M.I.; Petrov, A.N.; Kudela, K.

    2005-01-01

    In this work the features of low-energy proton flux increases in near-equatorial region (McIlvein parameter L th the proton flux (with energy from tens keV up to several MeV) increases are registering regularly. However modern proton flux models (for example AP8 model) works at L>1.15 only and does not take into account near-equatorial protons. These fluxes are not too big, but the investigation of this phenomenon is important in scope of atmosphere-ionosphere connections and mechanisms of particles transport in magnetosphere. In according to double charge-exchange model the proton flux in near-equatorial region does not depend on geomagnetic local time (MLT) and longitude. However the Azur satellite data and Kosmos-484, MIR station and Active satellite data revealed the proton flux dependence on longitude. The other feature of near-equatorial proton flux is the dependence on geomagnetic local time revealed in the Sampex satellite experiment and other experiments listed above. In this work the dependences on MLT and longitude are investigated using the Active satellite (30-500 keV) and Sampex satellite (>800 keV). This data confirms that main sources of near-equatorial protons are radiation belts and ring current. The other result is that near-equatorial protons are quasi-trapped. The empirical proton flux dependences on L, B at near-equatorial longitudes are presented. (author)

  1. Ligands in PSI structures

    International Nuclear Information System (INIS)

    Kumar, Abhinav; Chiu, Hsiu-Ju; Axelrod, Herbert L.; Morse, Andrew; Elsliger, Marc-André; Wilson, Ian A.; Deacon, Ashley

    2010-01-01

    A survey of the types and frequency of ligands that are bound to PSI structures is analyzed as well as their utility in functional annotation of previously uncharacterized proteins. Approximately 65% of PSI structures report some type of ligand(s) that is bound in the crystal structure. Here, a description is given of how such ligands are handled and analyzed at the JCSG and a survey of the types, variety and frequency of ligands that are observed in the PSI structures is also compiled and analyzed, including illustrations of how these bound ligands have provided functional clues for annotation of proteins with little or no previous experimental characterization. Furthermore, a web server was developed as a tool to mine and analyze the PSI structures for bound ligands and other identifying features

  2. Air-Sea Coupling Over The Equatorial Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Gopika, N.

    .1 Introduction 13 1.2 Equatorial Indian Ocean 13 1.3 Geographic location of the study area 17 1.4 Previous Work 18 1.5 Present Work 27 1.5.1 Motivation 27 1.5.2 Objectives 27 Chapter 2: Data and Methods 29 2... 1.5.1 Motivation Equatorial regions are special areas of the world ocean where intense air- sea interaction takes place and the ocean and atmosphere is tightly coupled. Equatorial Indian Ocean, in spite of its very special characteristics...

  3. Strong Equatorial Seasonality during Early Eocene greenhouse

    Science.gov (United States)

    Samanta, Arpita; Sarkar, Anindya

    2017-04-01

    A warm greenhouse climate, punctuated by a series of rapid warming events (known as hyperthermals), is characteristic of the Late Paleocene to Early Eocene period. Rapid addition of 13C depleted carbon to the exogenic carbon cycle, in an otherwise overall higher atmospheric CO2 level, is thought to set off the hyperthermal events. For understanding the fate of ongoing global warming and response of the climate system and biota, researchers for past few decades are paying more attention to comprehend this climatic enigma. Existing proxies from the most distinct hyperthermal event i.e., PETM indicate that the mean annual sea surface temperature (MASST) was comparatively higher (by ˜8 ˚ C) at high latitude and to a lesser extent towards the equator. Apart from the prominent hyperthermal events the rest of the Early Eocene was significantly warmer and thought to be more equable compare to present. Terrestrial proxy records from the mid-latitude regions indicated that the Mean Annual Temperature (MAT) and Minimum Winter Temperature (MWT) was high, thus reducing the seasonality or difference between MWT and Maximum Summer Temperature (MST). In absence of proxy data from the low latitude region, a ≥40 ˚ C summer temperature was predicted assuming a mild Eocene temperature gradient of ˜0.4 ˚ C/ ˚ latitude and mid-latitude temperature data. Even question was raised about the existence of the tropical rain forest in such climatic extreme. Recent pollen census data, on contrary, suggest proliferation of the tropical rain forest during this climatic extreme. Important in this context is that there is a very few direct evidence of Late Paleocene-Early Eocene MAT and seasonality data from the low latitude/equatorial regions. To resolve this issue, oxygen and carbon isotope ratios of larger benthic foraminifera (Nummulites burdigalensis) were measured in laser based carbonate device attached with the Delta V advantage continuous flow stable isotope ratio mass spectrometer

  4. Conservatives Anticipate and Experience Stronger Emotional Reactions to Negative Outcomes.

    Science.gov (United States)

    Joel, Samantha; Burton, Caitlin M; Plaks, Jason E

    2014-02-01

    The present work examined whether conservatives and liberals differ in their anticipation of their own emotional reactions to negative events. In two studies, participants imagined experiencing positive or negative outcomes in domains that do not directly concern politics. In Study 1, 190 American participants recruited online (64 male, Mage  = 32 years) anticipated their emotional responses to romantic relationship outcomes. In Study 2, 97 Canadian undergraduate students (26 male, Mage  = 21 years) reported on their anticipated and experienced emotional responses to academic outcomes. In both studies, more conservative participants predicted they would feel stronger negative emotions following negative outcomes than did more liberal participants. Furthermore, a longitudinal follow-up of Study 2 participants revealed that more conservative participants actually felt worse than more liberal participants after receiving a lower-than-desired exam grade. These effects remained even when controlling for the Big Five traits, prevention focus, and attachment style (Study 1), and optimism (Study 2). We discuss how the relationship between political orientation and anticipated affect likely contributes to differences between conservatives and liberals in styles of decision and policy choices. © 2013 Wiley Periodicals, Inc.

  5. Stronger inducible defences enhance persistence of intraguild prey.

    Science.gov (United States)

    Kratina, Pavel; Hammill, Edd; Anholt, Bradley R

    2010-09-01

    1. Intraguild predation is widespread in nature despite its potentially destabilizing effect on food web dynamics. 2. Anti-predator inducible defences affect both birth and death rates of populations and have the potential to substantially modify food web dynamics and possibly increase persistence of intraguild prey. 3. In a chemostat experiment, we investigated the long-term effects of inducible defences on the dynamics of aquatic microbial food webs consisting of an intraguild predator, intraguild prey, and a basal resource. We controlled environmental conditions and selected strains of intraguild prey that varied in the strength of expressed inducible defences. 4. We found that intraguild prey with a stronger tendency to induce an anti-predator morphology persist for significantly longer periods of time. In addition, model selection analysis implied that flexibility in defensive phenotype (inducibility itself) is most likely the factor responsible for the enhanced persistence. 5. As patterns at the community level often emerge as a result of the life-history traits of individuals, we propose that inducible defences increase the persistence of populations and may contribute to the widespread occurrence of theoretically unstable intraguild predation systems in nature.

  6. Geochemistry of sediment cores of the western equatorial Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Murty, P.S.N.; Cronan, D.S.; Rao, Ch.M.; Paropkari, A.L.; Topgi, R.S.; Guptha, M.V.S.; Colley, N.

    Geochemical investigations including partition analysis have been carried out on nine sediment cores from the western equatorial Indian Ocean. The results show that a core from the Arabian Sea exhibits a greater terrigenous influence than cores from...

  7. Modelling the development of mixing height in near equatorial region

    Energy Technology Data Exchange (ETDEWEB)

    Samah, A.A. [Univ. of Malaya, Air Pollution Research Unit, Kuala Lumpur (Malaysia)

    1997-10-01

    Most current air pollution models were developed for mid-latitude conditions and as such many of the empirical parameters used were based on observations taken in the mid-latitude boundary layer which is physically different from that of the equatorial boundary layer. In the equatorial boundary layer the Coriolis parameter f is small or zero and moisture plays a more important role in the control of stability and the surface energy balance. Therefore air pollution models such as the OMLMULTI or the ADMS which were basically developed for mid-latitude conditions must be applied with some caution and would need some adaptation to properly simulate the properties of equatorial boundary layer. This work elucidates some of the problems of modelling the evolution of mixing height in the equatorial region. The mixing height estimates were compared with routine observations taken during a severe air pollution episodes in Malaysia. (au)

  8. Planktonic foraminifera from core tops of western equatorial Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Naidu, P.D.; Guptha, M.V.S.

    A set of seven core tops from western equatorial Indian ocean were analysed for planktonic foraminifera, which has yielded 20 planktonic foraminiferal species. Among them Globorotalia menardii, Globigerinoides sacculifer and G. ruber constitute...

  9. ITER L 6 equatorial maintenance duct remote handling study

    International Nuclear Information System (INIS)

    Millard, J.

    1996-09-01

    The status and conclusions of a preliminary study of equatorial maintenance duct remote handling is reported. Due to issues with the original duct design a significant portion of the study had to be refocused on equatorial duct layout studies. The study gives an overview of some of the options for design of these ducts and the impact of the design on the equipment to work in the duct. To develop a remote handling concept for creating access through the ducts the following design tasks should be performed: define the operations sequences for equatorial maintenance duct opening and closing; review the remote handling requirements for equatorial maintenance duct opening and closing; design concept for door and pipe handling equipment and to propose preliminary procedures for material handling outsides the duct. 35 figs

  10. An improved model of equatorial scintillation

    Science.gov (United States)

    Secan, J. A.; Bussey, R. M.; Fremouw, E. J.; Basu, Sa.

    1995-05-01

    One of the main limitations of the modeling work that went into the equatorial section of the Wideband ionospheric scintillation model (WBMOD) was that the data set used in the modeling was limited to two stations near the dip equator (Ancon, Peru, and Kwajalein Island, in the North Pacific Ocean) at two fixed local times (nominally 1000 and 2200). Over the past year this section of the WBMOD model has been replaced by a model developed using data from three additional stations (Ascension Island, in the South Atlantic Ocean, Huancayo, Peru, and Manila, Phillipines; data collected under the auspices of the USAF Phillips Laboratory Geophysics Directorate) which provide a greater diversity in both latitude and longitude, as well as cover the entire day. The new model includes variations with latitude, local time, longitude, season, solar epoch, and geomagnetic activity levels. The way in which the irregularity strength parameter CkL is modeled has also been changed. The new model provides the variation of the full probability distribution function (PDF) of log (CkL) rather than simply the average of log (CkL). This permits the user to specify a threshold on scintillation level, and the model will calculate the percent of the time that scintillation will exceed that level in the user-specified scenario. It will also permit calculation of scintillation levels at a user-specified percentile. A final improvement to the WBMOD model is the implementation of a new theory for calculating S4 on a two-way channel.

  11. Geomagnetic storm and equatorial spread-F

    Directory of Open Access Journals (Sweden)

    F. Becker-Guedes

    2004-09-01

    Full Text Available In August 2000, a new ionospheric sounding station was established at Sao Jose dos Campos (23.2° S, 45.9° W; dip latitude 17.6° S, Brazil, by the University of Vale do Paraiba (UNIVAP. Another ionospheric sounding station was established at Palmas (10.2° S, 48.2° W; dip latitude 5.5° S, Brazil, in April 2002, by UNIVAP in collaboration with the Lutheran University Center of Palmas (CEULP, Lutheran University of Brazil (ULBRA. Both the stations are equipped with digital ionosonde of the type known as Canadian Advanced Digital Ionosonde (CADI. In order to study the effects of geomagnetic storms on equatorial spread-F, we present and discuss three case studies, two from the ionospheric sounding observations at Sao Jose dos Campos (September and November 2000 and one from the simultaneous ionospheric sounding observations at Sao Jose dos Campos and Palmas (July 2003. Salient features from these ionospheric observations are presented and discussed in this paper. It has been observed that sometimes (e.g. 4-5 November 2000 the geomagnetic storm acts as an inhibitor (high strong spread-F season, whereas at other times (e.g. 11-12 July 2003 they act as an initiator (low strong spread-F season, possibly due to corresponding changes in the quiet and disturbed drift patterns during different seasons.

  12. Radiation protection in hospitals of Equatorial Guinea

    International Nuclear Information System (INIS)

    Rabat Macambo, P.

    2001-01-01

    With a population of four hundred thousand (400.000) inhabitants and distributed in a territory of 28 thousand (28.000) km 2 , the use of ionizing radiations for medical practice in Equatorial Guinea is few and decreasing. It is used for diagnostic practices in the main hospitals of the country, where the work burden is not over 20 patients per day. The political, social and economical embryonic development of the country until recently had a negative influence on indicators and health organisations, so that even now the country does not have any radiological protection law, this shortness, in addition with the old architectural structure that x ray tools is lodging, as well as dosimetrical lack of employed staff, put this staff under risk of electromagnetic energy. This is to show the present survey of medical activities with ionizing radiation and to request technical support for implementing suitably the basic standards of radiation protection which will help us as basis for the elaboration outline law, on radiological protection in accordance with the new guidelines of the International Atomic Energy Agency. (author)

  13. Equatorial Magnetohydrodynamic Shallow Water Waves in the Solar Tachocline

    Science.gov (United States)

    Zaqarashvili, Teimuraz

    2018-03-01

    The influence of a toroidal magnetic field on the dynamics of shallow water waves in the solar tachocline is studied. A sub-adiabatic temperature gradient in the upper overshoot layer of the tachocline causes significant reduction of surface gravity speed, which leads to trapping of the waves near the equator and to an increase of the Rossby wave period up to the timescale of solar cycles. Dispersion relations of all equatorial magnetohydrodynamic (MHD) shallow water waves are obtained in the upper tachocline conditions and solved analytically and numerically. It is found that the toroidal magnetic field splits equatorial Rossby and Rossby-gravity waves into fast and slow modes. For a reasonable value of reduced gravity, global equatorial fast magneto-Rossby waves (with the spatial scale of equatorial extent) have a periodicity of 11 years, matching the timescale of activity cycles. The solutions are confined around the equator between latitudes ±20°–40°, coinciding with sunspot activity belts. Equatorial slow magneto-Rossby waves have a periodicity of 90–100 yr, resembling the observed long-term modulation of cycle strength, i.e., the Gleissberg cycle. Equatorial magneto-Kelvin and slow magneto-Rossby-gravity waves have the periodicity of 1–2 years and may correspond to observed annual and quasi-biennial oscillations. Equatorial fast magneto-Rossby-gravity and magneto-inertia-gravity waves have periods of hundreds of days and might be responsible for observed Rieger-type periodicity. Consequently, the equatorial MHD shallow water waves in the upper overshoot tachocline may capture all timescales of observed variations in solar activity, but detailed analytical and numerical studies are necessary to make a firm conclusion toward the connection of the waves to the solar dynamo.

  14. On Irrotational Flows Beneath Periodic Traveling Equatorial Waves

    Science.gov (United States)

    Quirchmayr, Ronald

    2017-06-01

    We discuss some aspects of the velocity field and particle trajectories beneath periodic traveling equatorial surface waves over a flat bed in a flow with uniform underlying currents. The system under study consists of the governing equations for equatorial ocean waves within a non-inertial frame of reference, where Euler's equation of motion has to be suitably adjusted, in order to account for the influence of the earth's rotation.

  15. Meridional equatorial electrojet current in the American sector

    Directory of Open Access Journals (Sweden)

    R. G. Rastogi

    Full Text Available Huancayo is the only equatorial electrojet station where the daytime increase of horizontal geomagnetic field (H is associated with a simultaneous increase of eastward geomagnetic field (Y. It is shown that during the counter electrojet period when ∆H is negative, ∆Y also becomes negative. Thus, the diurnal variation of ∆Y at equatorial latitudes is suggested to be a constituent part of the equatorial electrojet current system. Solar flares are known to increase the H field at an equatorial station during normal electrojet conditions (nej. At Huancayo, situated north of the magnetic equator, the solar flare effect, during nej, consists of positive impulses in H and Y and negative impulse in Z field. During counter electrojet periods (cej, a solar flare produces a negative impulse in H and Y and a positive impulse in Z at Huancayo. It is concluded that both the zonal and meridional components of the equatorial electrojet in American longitudes, as in Indian longitudes, flows in the same, E region of the ionosphere.

    Key words. Geomagnetism and paleomagnetism (dynamo theories · Ionosphere (equatorial ionosphere; ionosphere disturbances

  16. Meridional equatorial electrojet current in the American sector

    Directory of Open Access Journals (Sweden)

    R. G. Rastogi

    1999-02-01

    Full Text Available Huancayo is the only equatorial electrojet station where the daytime increase of horizontal geomagnetic field (H is associated with a simultaneous increase of eastward geomagnetic field (Y. It is shown that during the counter electrojet period when ∆H is negative, ∆Y also becomes negative. Thus, the diurnal variation of ∆Y at equatorial latitudes is suggested to be a constituent part of the equatorial electrojet current system. Solar flares are known to increase the H field at an equatorial station during normal electrojet conditions (nej. At Huancayo, situated north of the magnetic equator, the solar flare effect, during nej, consists of positive impulses in H and Y and negative impulse in Z field. During counter electrojet periods (cej, a solar flare produces a negative impulse in H and Y and a positive impulse in Z at Huancayo. It is concluded that both the zonal and meridional components of the equatorial electrojet in American longitudes, as in Indian longitudes, flows in the same, E region of the ionosphere.Key words. Geomagnetism and paleomagnetism (dynamo theories · Ionosphere (equatorial ionosphere; ionosphere disturbances

  17. The seasonal march of the equatorial Pacific upper-ocean and its El Niño variability

    Science.gov (United States)

    Gasparin, Florent; Roemmich, Dean

    2017-08-01

    Based on two modern data sets, the climatological seasonal march of the upper-ocean is examined in the equatorial Pacific for the period 2004-2014, because of its large contribution to the total variance, its relationship to El Niño, and its unique equatorial wave phenomena. Argo provides a broadscale view of the equatorial Pacific upper-ocean based on subsurface temperature and salinity measurements for the period 2004-2015, and satellite altimetry provides synoptic observations of the sea surface height (SSH) for the period 1993-2015. Using either 11-year (1993-2003/2004-2014) time-series for averaging, the seasonal Rossby waves stands out clearly and eastward intraseasonal Kelvin wave propagation is strong enough in individual years to leave residuals in the 11-year averages, particularly but not exclusively, during El Niño onset years. The agreement of altimetric SSH minus Argo steric height (SH) residuals with GRACE ocean mass estimates confirms the scale-matching of in situ variability with that of satellite observations. Surface layer and subsurface thermohaline variations are both important in determining SH and SSH basin-wide patterns. The SH/SSH October-November maximum in the central-eastern Pacific is primarily due to a downward deflection of the thermocline (∼20 m), causing a warm subsurface anomaly (>1 °C), in response to the phasing of downwelling intraseasonal Kelvin and seasonal Rossby waves. Compared with the climatology, the stronger October-November maximum in the 2004-2014 El Niño composites is due to higher intraseasonal oscillations and interannual variability. Associated with these equatorial wave patterns along the thermocline, the western warm/fresh pool waters move zonally at interannual timescales through zonal wind stress and pressure gradient fluctuations, and cause substantial fresh (up to 0.6 psu) and warm (∼1 °C higher than the climatology) anomalies in the western-central Pacific surface-layer during the El Niño onset

  18. Is Polar Amplification Deeper and Stronger than Dynamicists Assume?

    Science.gov (United States)

    Scheff, J.; Maroon, E.

    2017-12-01

    In the CMIP multi-model mean under strong future warming, Arctic amplification is confined to the lower troposphere, so that the meridional gradient of warming reverses around 500 mb and the upper troposphere is characterized by strong "tropical amplification" in which warming weakens with increasing latitude. This model-derived pattern of warming maxima in the upper-level tropics and lower-level Arctic has become a canonical assumption driving theories of the large-scale circulation response to climate change. Yet, several lines of evidence and reasoning suggest that Arctic amplification may in fact extend through the entire depth of the troposphere, and/or may be stronger than commonly modeled. These include satellite Microwave Sounding Unit (MSU) temperature trends as a function of latitude and vertical level, the recent discovery that the extratropical negative cloud phase feedback in models is largely spurious, and the very strong polar amplification observed in past warm and lukewarm climates. Such a warming pattern, with deep, dominant Arctic amplification, would have very different implications for the circulation than a canonical CMIP-like warming: instead of slightly shifting poleward and strengthening, eddies, jets and cells might shift equatorward and considerably weaken. Indeed, surface winds have been mysteriously weakening ("stilling") at almost all stations over the last half-century or so, there has been no poleward shift in northern hemisphere circulation metrics, and past warm climates' subtropics were apparently quite wet (and their global ocean circulations were weak.) To explore these possibilities more deeply, we examine the y-z structure of warming and circulation changes across a much broader range of models, scenarios and time periods than the CMIP future mean, and use an MSU simulator to compare them to the satellite warming record. Specifically, we examine whether the use of historical (rather than future) forcing, AMIP (rather than CMIP

  19. Increasing Arctic sea ice export driven by stronger winds

    Science.gov (United States)

    Sorteberg, A.; Smedsrud, L. H.; Sirevaag, A.; Kloster, K.

    2010-12-01

    Arctic sea ice area has decreased steadily over the last three decades. A thinner and more seasonal Arctic ice cover, related to increased long wave radiation, has become evident. Changes in circulation, including drift patterns of the Arctic pack ice, have been less obvious. Arctic sea ice export estimates have been hampered by low resolution spatial and temporal satellite imagery, especially during summer, making accurate detection difficult. Here we present a new ice area export dataset calculated from sea ice motion and concentration profiles along 79N. Ice drift vectors are calculated from ice feature displacement using Envisat ASAR WideSwath images every 3 days from 2004 while ice concentration is based on DMSP F13 SSMI and AQUA AMSR-E brightness temperature data. The two data sets are combined to give the ice-area flux in consecutive 3-day periods, uninterrupted year-round coverage along 79N. It is shown that sea ice export variability is closely linked to the geostrophic wind in the Fram Strait (correlation of 0.84). Using geostrophic winds from reanalysis back to the 1950s as a proxy for ice export indicates that the Arctic sea ice has annually lost an increasing area since the 1950's driven by stronger winds. Ice concentration has decreased slightly, but does not contribute significantly. The ice export has overall increased by ~25% over the period. Using cyclone tracking the changes in winds seems directly related to a higher low pressure activity in the Nordic Seas. Our results demonstrate that the changes in atmospheric circulation over the Arctic and sub-Arctic have contributed to a trend in the Fram Strait ice export. The Fram Strait between Greenland and Svalbard with average sea ice concentration for summer (red, June through August) and winter (black, January through March). Solid lines are 50%, dashed lines are 15%. Above mean southward ice drift across 79N from August 2004 to July 2010 in 1 degree bins based on SAR imagery, and mean ice

  20. Neotectonics in the northern equatorial Brazilian margin

    Science.gov (United States)

    Rossetti, Dilce F.; Souza, Lena S. B.; Prado, Renato; Elis, Vagner R.

    2012-08-01

    An increasing volume of publications has addressed the role of tectonics in inland areas of northern Brazil during the Neogene and Quaternary, despite its location in a passive margin. Hence, northern South America plate in this time interval might have not been as passive as usually regarded. This proposal needs further support, particularly including field data. In this work, we applied an integrated approach to reveal tectonic structures in Miocene and late Quaternary strata in a coastal area of the Amazonas lowland. The investigation, undertaken in Marajó Island, mouth of the Amazonas River, consisted of shallow sub-surface geophysical data including vertical electric sounding and ground penetrating radar. These methods were combined with morphostructural analysis and sedimentological/stratigraphic data from shallow cores and a few outcrops. The results revealed two stratigraphic units, a lower one with Miocene age, and an upper one of Late Pleistocene-Holocene age. An abundance of faults and folds were recorded in the Miocene deposits and, to a minor extent, in overlying Late Pleistocene-Holocene strata. In addition to characterize these structures, we discuss their origin, considering three potential mechanisms: Andean tectonics, gravity tectonics related to sediment loading in the Amazon Fan, and rifting at the continental margin. Amongst these hypotheses, the most likely is that the faults and folds recorded in Marajó Island reflect tectonics associated with the history of continental rifting that gave rise to the South Atlantic Ocean. This study supports sediment deposition influenced by transpression and transtension associated with strike-slip divergence along the northern Equatorial Brazilian margin in the Miocene and Late Pleistocene-Holocene. This work records tectonic evidence only for the uppermost few ten of meters of this sedimentary succession. However, available geological data indicate a thickness of up to 6 km, which is remarkably thick for

  1. Equatorial Kelvin waves: A UARS MLS view

    Science.gov (United States)

    Canziani, Pablo O.; Holton, James R.; Fishbein, Evan; Froidevaux, Lucien; Waters, Joe W.

    1994-01-01

    Data from the Microwave Limb Sounder (MLS) instrument on the Upper Atmosphere Research Satellite (UARS) are used to compare two periods of Kelvin wave activity during different stages of the equatorial quasi-biennial oscillation. The analysis is carried out using an asynoptic mapping technique. A wide bandpass filter is used to isolate the frequency bands where Kelvin waves have been identified in previous studies. Time-height and time-latitude plots of the bandpassed data are used to identify Kelvin wave activity in the temperature and ozone fields. Frequency spectra of temperature and ozone amplitudes are constructed to further analyze the latitudinal and meridional distribution of Kelvin wave activity in zonal wavenumbers 1 and 2. The characteristics identified in these plots agree well with theoretical predictions and previous observations of middle atmosphere Kelvin waves. The time-height and time-latitude plots support the existence of Kelvin waves in discrete frequency bands; the slow, fast, and ultrafast Kelvin modes are all identified in the data. The characteristics of these modes do not vary much despite different mean flow conditions in the two periods examined. For the Kelvin wave-induced perturbations in ozone, the change from a transport-dominated regime below 10 hPa to a photochemically controlled regime above 10 hPa is clearly apparent in the height dependence of the phase difference between temperature and ozone. The ratios of the ozone perturbation amplitude to the temperature perturbation amplitude for the various observed Kelvin wave modes are in agreement with model estimates and LIMS (Limb Infrared Monitor of the Stratosphere) observations in the lower half of the region sampled but appear to be too large in the upper stratosphere and lower mesosphere.

  2. Assessment of prediction skill in equatorial Pacific Ocean in high resolution model of CFS

    Science.gov (United States)

    Arora, Anika; Rao, Suryachandra A.; Pillai, Prasanth; Dhakate, Ashish; Salunke, Kiran; Srivastava, Ankur

    2018-01-01

    The effect of increasing atmospheric resolution on prediction skill of El Niño southern oscillation phenomenon in climate forecast system model is explored in this paper. Improvement in prediction skill for sea surface temperature (SST) and winds at all leads compared to low resolution model in the tropical Indo-Pacific basin is observed. High resolution model is able to capture extreme events reasonably well. As a result, the signal to noise ratio is improved in the high resolution model. However, spring predictability barrier (SPB) for summer months in Nino 3 and Nino 3.4 region is stronger in high resolution model, in spite of improvement in overall prediction skill and dynamics everywhere else. Anomaly correlation coefficient of SST in high resolution model with observations in Nino 3.4 region targeting boreal summer months when predicted at lead times of 3-8 months in advance decreased compared its lower resolution counterpart. It is noted that higher variance of winds predicted in spring season over central equatorial Pacific compared to observed variance of winds results in stronger than normal response on subsurface ocean, hence increases SPB for boreal summer months in high resolution model.

  3. One Year After Fukushima, Nuclear Safety Is Stronger

    International Nuclear Information System (INIS)

    2012-01-01

    Full text: Nuclear power is safer than it was a year ago as the nuclear industry, regulators and governments act on the lessons of Fukushima, but that safety must never be taken for granted, said Yukiya Amano, Director General of the International Atomic Energy Agency (IAEA). Speaking ahead of the first anniversary of the Fukushima Daiichi nuclear accident on 11 March, Amano said a culture of constant vigilance and improvement was vital to ensure that the benefits of nuclear power could be harnessed as safely as humanly possible. 'Nuclear safety is stronger than it was a year ago', he said. 'Fukushima Daiichi was a very serious accident, but we know what went wrong and we have a clear course of action to tackle those causes - not only in Japan, but anywhere in the world. 'Now we have to keep up the momentum. Complacency can kill'. On 11 March 2011 a huge earthquake and tsunami left more than 20 000 people dead or missing in eastern Japan. Amidst widespread destruction, the tsunami slammed into the Fukushima Daiichi Nuclear Power Station, disabling cooling systems and leading to fuel meltdowns in three of the six Units. The accident was a jolt to the nuclear industry, regulators and governments. It was triggered by a massive force of nature, but it was existing weaknesses of design regarding defence against natural hazards, regulatory oversight, accident management and emergency response that allowed it to unfold as it did. For example: The nuclear regulator was not sufficiently independent, allowing weak oversight of the operator, TEPCO, and regulatory requirements fell short of international best practice; Not enough attention was paid to guarding against possible extreme events at the Fukushima Daiichi site, leaving critical safety functions such as cooling systems vulnerable to the tsunami; Training to respond to serious accidents was inadequate, as were mitigation measures to prevent hydrogen explosions and protect the venting system; and Accident command lines

  4. Should the Master Equatorial Be a Slave?

    Science.gov (United States)

    Gawronski, W.; Ahlstrom, H. G., Jr.; Bernardo, A. M.

    2000-10-01

    The article describes the existing 70-m antenna control system, the master equatorial (ME) control system, and their "master--slave" interaction through the autocollimator coupling. The analysis describes the open-loop models of the antenna and ME, obtained through field tests and system identification. Next, the performances of closed-loop systems of the antenna and ME are evaluated. The closed-loop performance indicates that a single control algorithm can replace three existing algorithms and that the mode-switching algorithm is no longer required. This new single control algorithm provides significant performance improvement at minimal cost, using primarily existing equipment. Different configurations of the antenna and ME are proposed and evaluated. In the existing configuration, the ME is a master: it follows a target, and the antenna is a slave, following the ME. This arrangement causes occasional problems. Since antenna drives were designed for rates smaller than 0.25 deg/s and for accelerations smaller than 0.2 deg/s^2, tracking at high rates (e.g., near the keyhole) may leave the antenna outside the autocollimator acquisition range. It causes the breakdown of the ME-antenna optical link and termination of the track. Here we analyze two new ME-antenna configurations. Configuration A is a modification of the existing configuration with new control algorithms and a command preprocessor added, where the antenna follows the ME. Configuration B also includes new control algorithms and a command preprocessor, but unlike Configuration A, the ME is a slave and follows the antenna. It serves, in effect, as an antenna position sensor. Analysis shows that both configurations are feasible for high-rate tracking using the existing autocollimator. Configuration B, however, is superior as it has much smaller autocollimator errors. Finally, for the existing configuration and for Configurations A, there is no provision for ME wrap direction, while Configuration B would

  5. Effect of geomagnetic storm conditions on the equatorial ionization anomaly and equatorial temperature anomaly

    Science.gov (United States)

    Bharti, Gaurav; Bag, T.; Sunil Krishna, M. V.

    2018-03-01

    The effect of the geomagnetic storm on the equatorial ionization anomaly (EIA) and equatorial temperature anomaly (ETA) has been studied using the atomic oxygen dayglow emissions at 577.7 nm (OI 557.7 nm) and 732.0 nm (OII 732.0 nm). For the purpose of this study, four intense geomagnetic storms during the ascending phase of solar cycle 24 have been considered. This study is primarily based on the results obtained using photochemical models with necessary inputs from theoretical studies and experimental observations. The latest reaction rate coefficients, quantum yields and the corresponding cross-sections have also been incorporated in these models. The volume emission rate of airglow emissions has been calculated using the neutral densities from NRLMSISE-00 and charged densities from IRI-2012 model. The modeled volume emission rate (VER) for OI 557.7 nm shows a positive correlation with the Dst index at 150 km and negative correlation with Dst at 250 and 280 km altitudes. Latitudinal profile of the greenline emission rate at different altitudes show a distinct behaviour similar to what has been observed in EIA with crests on either sides of the equator. The EIA crests are found to show poleward movement in the higher altitude regions. The volume emission rate of 732.0 nm emission shows a strong enhancement during the main phase of the storm. The changes observed in the airglow emission rates are explained with the help of variations induced in neutral densities and parameters related to EIA and ETA. The latitudinal variation of 732.0 nm emission rate is correlated to the variability in EIA during the storm period.

  6. Occurrence of Equatorial Plasma Bubbles during Intense Magnetic Storms

    Directory of Open Access Journals (Sweden)

    Chao-Song Huang

    2011-01-01

    Full Text Available An important issue in low-latitude ionospheric space weather is how magnetic storms affect the generation of equatorial plasma bubbles. In this study, we present the measurements of the ion density and velocity in the evening equatorial ionosphere by the Defense Meteorological Satellite Program (DMSP satellites during 22 intense magnetic storms. The DMSP measurements show that deep ion density depletions (plasma bubbles are generated after the interplanetary magnetic field (IMF turns southward. The time delay between the IMF southward turning and the first DMSP detection of plasma depletions decreases with the minimum value of the IMF Bz, the maximum value of the interplanetary electric field (IEF Ey, and the magnitude of the Dst index. The results of this study provide strong evidence that penetration electric field associated with southward IMF during the main phase of magnetic storms increases the generation of equatorial plasma bubbles in the evening sector.

  7. Molecular characterization of Cryptosporidium isolates from humans in Equatorial Guinea.

    Science.gov (United States)

    Blanco, María Alejandra; Iborra, Asunción; Vargas, Antonio; Nsie, Eugenia; Mbá, Luciano; Fuentes, Isabel

    2009-12-01

    The aim of the study was to perform a molecular characterization of clinical isolates of Cryptosporidium species from Equatorial Guinea. Standard laboratory methods were used to identify 35 cryptosporidiosis cases among 185 patients. PCR-RFLP successfully identified 34 Cryptosporidium species from these 35 cases, comprising C. parvum (52.9%), C. hominis (44.1%) and C. meleagridis (2.9%); over 90% of the species were isolated from HIV-positive patients. This is the first report of the molecular characterization of Cryptosporidium species isolated from humans in Equatorial Guinea and shows that zoonotic and anthroponotic transmission is present in this country.

  8. Longitudinal Variation and Waves in Jupiter's South Equatorial Wind Jet

    Science.gov (United States)

    Simon-Miller, A. A.; Rogers, John H.; Gierasch, Peter J.; Choi, David; Allison, Michael; Adamoli, Gianluigi; Mettig, Hans-Joerg

    2012-01-01

    We have conducted a detailed study of the cloud features in the strong southern equatorial wind jet near 7.5 S planetographic latitude. To understand the apparent variations in average zonal wind jet velocity at this latitude [e.g.. 1,2,3], we have searched for variations iIi both feature latitude and velocity with longitude and time. In particular, we focused on the repetitive chevron-shaped dark spots visible on most dates and the more transient large anticyclonic system known as the South Equatorial Disturbance (SED). These small dark spots are interpreted as cloud holes, and are often used as material tracers of the wind field.

  9. A first look at past sea surface temperatures in the equatorial Indian Ocean from Mg/Ca in foraminifera

    Digital Repository Service at National Institute of Oceanography (India)

    Saraswat, R.; Nigam, R.; Weldeab, S.; Mackensen, A.; Naidu, P.D.

    between the equatorial Indian Ocean SST and the equatorial Pacific SST suggests the possibility of a common mechanism controlling the SSTs in both the equatorial Indian Ocean and the Pacific Ocean. Citation: Saraswat, R., R. Nigam, S. Weldeab, A. Mackensen...

  10. A three-dimensional autonomous nonlinear dynamical system modelling equatorial ocean flows

    Science.gov (United States)

    Ionescu-Kruse, Delia

    2018-04-01

    We investigate a nonlinear three-dimensional model for equatorial flows, finding exact solutions that capture the most relevant geophysical features: depth-dependent currents, poleward or equatorial surface drift and a vertical mixture of upward and downward motions.

  11. Upper ocean circulation modulation by phytoplankton concentration in the Equatorial Pacific and the Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Nakamoto, S.; PrasannaKumar, S.; Oberhuber, J.M.; Sammarco, P.; Muneyama, K.; Sato, T.; AjoyKumar, A.; Frouin, R.

    Wind patterns in the equatorial Pacific and Indian oceans are the factors that regulate the chlorophyll pigment distributions in the equatorial region of these oceans. Trade winds and coastline of the Pacific basin supports wave-guide dynamics...

  12. Different Strokes: Spanish Policy toward Cuba and Equatorial ...

    African Journals Online (AJOL)

    Spanish policy toward Cuba and Equatorial Guinea up to the end of the 19th century differed markedly. The policy itself is difficult to define but the general principle emphasized the exploitation of the resources of the colonies for the benefit of Spain. It also provided for the spread of Spanish culture and the Christian faith.

  13. Clean advice for oily money : Consulting for Equatorial Guinea

    NARCIS (Netherlands)

    Lachotzki, F.; Karssing, E.D.

    2011-01-01

    Equatorial Guinea is one of the most extraordinary countries in the world, if also one of the most obscure. Its tremendous yearly revenue from the oil concessions it grants in its Gulf of Guinea territorial waters is little known, but so too is its abysmal record on human rights. The deep-rooted

  14. Relation between the continental TCZ and the TCZ over Equatorial ...

    Indian Academy of Sciences (India)

    First page Back Continue Last page Overview Graphics. Relation between the continental TCZ and the TCZ over Equatorial Indian Ocean. Competition: Air ascending in the TCZ descends in the surrounding region . So when there are two TCZs over the same longitudinal belt, each tries to suppress the other. Active spells of ...

  15. Variable influence on the equatorial troposphere associated with ...

    Indian Academy of Sciences (India)

    Sudden stratospheric warming (SSW) events are identified to investigate their influence on the equatorial tropospheric climate. Composite analysis of warming events from Era-Interim (1979–2013) record a cooling of the tropical lower stratosphere with corresponding changes in the mean meridional stratosphericcirculation.

  16. Characterisation of tectonic lineaments in the Central Equatorial ...

    African Journals Online (AJOL)

    Characterisation of tectonic lineaments in the Central Equatorial Atlantic region of Africa using Bouguer anomaly gravity data. ... Ife Journal of Science ... 3-D standard Euler deconvolution analysis was carried out on Bouguer anomaly gravity data for configuration definition and approximate depth estimate of tectonic ...

  17. Solar Wind Associated with Near Equatorial Coronal Hole

    Indian Academy of Sciences (India)

    2016-01-27

    Jan 27, 2016 ... Present study probes temporal changes in the area and radiative flux of near equatorial coronal hole associated with solar wind parameters such as wind speed, density, magnetic field and temperature. Using high temporal resolution data from SDO/AIA for the two wave-lengths 193 Å and 211 Å, area and ...

  18. equatorial electrojet strength in the african sector during high

    African Journals Online (AJOL)

    Preferred Customer

    electrojet current. The electric fields that drive the equatorial electrojet current have been found to consist of three components with different origins. (Reddy, 1981): a) an electric field originating in the dynamo action of the global scale wind system in the lower atmosphere, which is the driving electric field on quiet days with ...

  19. Equatorial electrojet in the south Atlantic anomaly region

    Indian Academy of Sciences (India)

    Ronchi C, Sudan R N and Similon P L 1990 Effect of short- scale turbulence on kilometer wavelength irregularities in the equatorial electrojet; J. Geophys. Res. 95 189–200. Sarabhai V and Nair K N 1971 Morphology of the geomag- netic field variations and a study of the interplanetary magnetic field fluctuations in relation ...

  20. Iron sources and pathways into the Pacific Equatorial Undercurrent

    NARCIS (Netherlands)

    Qin, Xuerong; Menviel, Laurie; Sen Gupta, Alex; van Sebille, Erik

    2016-01-01

    Using a novel observationally constrained Lagrangian iron model forced by outputs from an eddy-resolving biogeochemical ocean model, we examine the sensitivity of the Equatorial Undercurrent (EUC) iron distribution to EUC source region iron concentrations. We find that elevated iron concentrations

  1. Mesoscale model simulation of low level equatorial winds over ...

    Indian Academy of Sciences (India)

    http://www.ias.ac.in/article/fulltext/jess/118/04/0295-0307. Keywords. Equatorial region; low-level meteorological parameters; biomass burning; haze; southeast Asia; Sarawak. Abstract. The large-scale vegetation fires instigated by the local farmers during the dry period of the major El Ni˜no event in 1997 can be considered ...

  2. Solar Wind Associated with Near Equatorial Coronal Hole M ...

    Indian Academy of Sciences (India)

    2015-05-25

    May 25, 2015 ... Probably, during the early his- tory of solar system formation, strong solar wind might have played a dominant role. 355 .... (Atmospheric Imaging Assembly), we have considered near equatorial coronal hole data with 1 hour time ... thermal or kinetic energy of the solar wind? (iii) at what height in the solar ...

  3. A biweekly mode in the equatorial Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Sengupta, D.; Senan, R.; Murty, V.S.N.; Fernando, V.

    propagating biweekly waves with zonal wavelength in the range 2100 to 6100 km. An ocean model forced by high-resolution scatterometer wind stress is used to show that the observed biweekly variability is due to equatorially trapped mixed Rossby-gravity waves...

  4. Climate regulation of fire emissions and deforestation in equatorial Asia

    NARCIS (Netherlands)

    van der Werf, G. R.; Dempewolf, J.; Trigg, S. N.; Randerson, J. T.; Kasibhatla, P. S.; Giglio, L.; Murdiyarso, D.; Peters, W.; Morton, D. C.; Collatz, G. J.; Dolman, A. J.; Defries, R. S.

    2008-01-01

    Drainage of peatlands and deforestation have led to large-scale fires in equatorial Asia, affecting regional air quality and global concentrations of greenhouse gases. Here we used several sources of satellite data with biogeochemical and atmospheric modeling to better understand and constrain fire

  5. The equatorial disc of the Be star X Persei

    NARCIS (Netherlands)

    Telting, JH; Waters, LBFM; Roche, P; Boogert, ACA; Clark, JS; de Martino, D; Persi, P

    1998-01-01

    We study the long-term behaviour of the equatorial disc of the Be/X-ray binary X Persei (X Per), combining new low-resolution IUE spectra and IR photometry with UV, optical and IR observations collected from the literature. We find that the near-UV continuum level of X Per varies along with the

  6. Equatorial electrojet in the Indian region during the geomagnetic ...

    Indian Academy of Sciences (India)

    1998-11-14

    Nov 14, 1998 ... November 1998 reaching a minimum of about –120 nT around midnight of 13–14 November 1998. Features of the equatorial electrojet in the Indian region are studied during the geomagnetic storm event of 13–14 November 1998, based on the geomagnetic data from the chain of observatories in India.

  7. Observations of ULF wave related equatorial electrojet and density fluctuations

    Science.gov (United States)

    Yizengaw, E.; Zesta, E.; Biouele, C. M.; Moldwin, M. B.; Boudouridis, A.; Damtie, B.; Mebrahtu, A.; Anad, F.; Pfaff, R. F.; Hartinger, M.

    2013-10-01

    We report on Pc5 wave related electric field and vertical drift velocity oscillations at the equator as observed by ground magnetometers for an extended period on 9 August 2008. We show that the magnetometer-estimated equatorial E×B drift oscillates with the same frequency as ULF Pc5 waves, creating significant ionospheric density fluctuations. We also show ionospheric density fluctuations during the period when we observed ULF wave activity. At the same time, we detect the ULF activity on the ground using ground-based magnetometer data from the African Meridian B-field Education and Research (AMBER) and the South American Meridional B-field Array (SAMBA). From space, we use magnetic field observations from the GOES 12 and the Communication/Navigation Outage and Forecast System (C/NOFS) satellites. Upstream solar wind conditions are provided by the ACE spacecraft. We find that the wave power observed on the ground also occurs in the upstream solar wind and in the magnetosphere. All these observations demonstrate that Pc5 waves with a likely driver in the solar wind can penetrate to the equatorial ionosphere and modulate the equatorial electrodynamics. While no direct drift measurements from equatorial radars exist for the 9 August 2008 event, we used JULIA 150 km radar drift velocities observed on 2 May 2010 and found similar fluctuations with the period of 5-8 min, as a means of an independent confirmation of our magnetometer derived drift dynamics.

  8. Yanai waves in the western equatorial Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Chatterjee, A; Shankar, D.; McCreary, J.P.; Vinayachandran, P.N.

    Observations and models have shown the presence of intraseasonal fluctuations in 20-30-day and 10-20-day bands in the equatorial Indian Ocean west of 60 degrees E (WEIO). Their spatial and temporal structures characterize them as Yanai waves, which...

  9. Variable influence on the equatorial troposphere associated with ...

    Indian Academy of Sciences (India)

    DOI 10.1007/s12040-017-0802-6. Variable influence on the equatorial troposphere associated with SSW using ERA-Interim. Sourabh Bal1,4,∗. , Semjon Schimanke2, Thomas Spangehl3 and Ulrich Cubasch1. 1Institute for Meteorology, Freie Universität, Berlin, Germany. 2Swedish Meteorological and Hydrological Institute, ...

  10. Post-midnight occurrence of equatorial plasma bubbles

    Science.gov (United States)

    Ajith, K. K.; Otsuka, Yuichi; Yamamoto, Mamoru; Yokoyama, Tatsuhiro; Tulasiram, S.

    2016-07-01

    The equatorial plasma bubbles (EPBs)/equatorial spread F (ESF) irregularities are an important topic of space weather interest because of their impact on transionospheric radio communications, satellite-based navigation and augmentation systems. This local plasma depleted structures develop at the bottom side F layer through Rayleigh-Taylor instability and rapidly grow to topside ionosphere via polarization electric fields within them. The steep vertical gradients due to quick loss of bottom side ionization and rapid uplift of equatorial F layer via prereversal enhancement (PRE) of zonal electric field makes the post-sunset hours as the most preferred local time for the formation of EPBs. However, there is a different class of irregularities that occurs during the post-midnight hours of June solstice reported by the previous studies. The occurrence of these post-midnight EPBs maximize during the low solar activity periods. The growth characteristics and the responsible mechanism for the formation of these post-midnight EPBs are not yet understood. Using the rapid beam steering ability of 47 MHz Equatorial Atmosphere Radar (EAR) at Kototabang (0.2°S geographic latitude, 100.3°E geographic longitude, and 10.4°S geomagnetic latitude), Indonesia, the spatial and temporal evolution of equatorial plasma bubbles (EPBs) were examined to classify the evolutionary-type EPBs from those which formed elsewhere and drifted into the field of view of radar. The responsible mechanism for the genesis of summer time post-midnight EPBs were discussed in light of growth rate of Rayleigh-Taylor instability using SAMI2 model.

  11. Equatorial and Low-Latitude Ionospheric Response to the Extreme Space Weather Event of March 2015, in the Brazilian Sector.

    Science.gov (United States)

    Fagundes, P. R.; Cardoso, F. A.; Fejer, B. G.; Kavutarapu, V.; Ribeiro, B. A.; Pillat, V. G.

    2015-12-01

    Fagundes PR, Cardoso FA and Venkatesh KPhysics and Astronomy Laboratory, Universidade do Vale do Paraiba (UNIVAP), Sao Jose dos Campos, Sao Paulo, Brazil In the present investigation we discuss the results on the response of the ionosphere (F-region) in the Brazilian sector, during extreme space weather event of March 2015. This geomagnetic storm has been considered as one of strongest storms in the solar cycle 24 where, the Dst index reached a minimum of -227 nT at 23:00 UT (17/03/2015) with KP reaching to 8-, and the monthly mean F10.7 solar flux was 125 sfu. This space weather event was studied using a large network of 110 GPS stations. It has been noticed that the Total Electron Content (TEC) was severely disturbed during the geomagnetic storm main and recovery phases. A wavelike oscillation with three peaks is observed from equator to low latitudes during the storm main phase on 17th and 18th March, 2015. Using a latitudinal chain of 8 GPS stations from equatorial region to low latitudes the storm time behavior of the Equatorial Ionization Anomaly (EIA) is investigated. It was noticed that the wavelike oscillation peak latitudinal extent decreases from the beginning of main phase to the recovery phase. The first maximum extends beyond from 2oS to 20oS, the second one from 8oS to 18oS and the third one from 13oS to 17oS. In addition, a strong negative phase in TEC variations is observed during the recovery phase on March 18, 2015. This negative phase is found to be stronger at low-latitude compared to the equatorial region. An anomalous behavior of EIA caused by the wavelike oscillations is observed during the main phase on March 17, 2015. Also, due to the strong negative phase in TEC resulted in strong EIA suppression on March 18, 2015.

  12. Selectivity in ligand binding to uranyl compounds: A synthetic, structural, thermodynamic and computational study

    International Nuclear Information System (INIS)

    Arnold, John

    2015-01-01

    The uranyl cation (UO 2 2+ ) is the most abundant form of uranium on the planet. It is estimated that 4.5 billion tons of uranium in this form exist in sea water. The ability to bind and extract the uranyl cation from aqueous solution while separating it from other elements would provide a limitless source of nuclear fuel. A large body of research concerns the selective recognition and extraction of uranyl. A stable molecule, the cation has a linear O=U=O geometry. The short U-O bonds (1.78 Å) arise from the combination of uranium 5f/6d and oxygen 2p orbitals. Due to the oxygen moieties being multiply bonded, these sites were not thought to be basic enough for Lewis acidic coordination to be a viable approach to sequestration. The goal of this research is thus to broaden the coordination chemistry of the uranyl ion by studying new ligand systems via synthetic, structural, thermodynamic and computational methods. It is anticipated that this fundamental science will find use beyond actinide separation technologies in areas such as nuclear waste remediation and nuclear materials. The focus of this study is to synthesize uranyl complexes incorporating amidinate and guanidinate ligands. Both synthetic and computational methods are used to investigate novel equatorial ligand coordination and how this affects the basicity of the oxo ligands. Such an understanding will later apply to designing ligands incorporating functionalities that can bind uranyl both equatorially and axially for highly selective sequestration. Efficient and durable chromatography supports for lanthanide separation will be generated by (1) identifying robust peptoid-based ligands capable of binding different lanthanides with variable affinities, and (2) developing practical synthetic methods for the attachment of these ligands to Dowex ion exchange resins.

  13. Selectivity in ligand binding to uranyl compounds: A synthetic, structural, thermodynamic and computational study

    Energy Technology Data Exchange (ETDEWEB)

    Arnold, John [Univ. of California, Berkeley, CA (United States)

    2015-01-21

    The uranyl cation (UO₂²⁺) is the most abundant form of uranium on the planet. It is estimated that 4.5 billion tons of uranium in this form exist in sea water. The ability to bind and extract the uranyl cation from aqueous solution while separating it from other elements would provide a limitless source of nuclear fuel. A large body of research concerns the selective recognition and extraction of uranyl. A stable molecule, the cation has a linear O=U=O geometry. The short U-O bonds (1.78 Å) arise from the combination of uranium 5f/6d and oxygen 2p orbitals. Due to the oxygen moieties being multiply bonded, these sites were not thought to be basic enough for Lewis acidic coordination to be a viable approach to sequestration. The goal of this research is thus to broaden the coordination chemistry of the uranyl ion by studying new ligand systems via synthetic, structural, thermodynamic and computational methods. It is anticipated that this fundamental science will find use beyond actinide separation technologies in areas such as nuclear waste remediation and nuclear materials. The focus of this study is to synthesize uranyl complexes incorporating amidinate and guanidinate ligands. Both synthetic and computational methods are used to investigate novel equatorial ligand coordination and how this affects the basicity of the oxo ligands. Such an understanding will later apply to designing ligands incorporating functionalities that can bind uranyl both equatorially and axially for highly selective sequestration. Efficient and durable chromatography supports for lanthanide separation will be generated by (1) identifying robust peptoid-based ligands capable of binding different lanthanides with variable affinities, and (2) developing practical synthetic methods for the attachment of these ligands to Dowex ion exchange resins.

  14. Stronger learning recruits additional cell-signaling cascades: c-Jun-N-terminal kinase 1 (JNK1) is necessary for expression of stronger contextual fear conditioning.

    Science.gov (United States)

    Leach, Prescott T; Kenney, Justin W; Gould, Thomas J

    2015-02-01

    Increased training often results in stronger memories but the neural changes responsible for these stronger memories are poorly understood. It is proposed here that higher levels of training that result in stronger memories recruit additional cell signaling cascades. This study specifically examined if c-Jun N-terminal kinase 1 (JNK1) is involved in the formation of stronger fear conditioning memories. Wildtype (WT), JNK1 heterozygous (Het), and JNK1 knockout (KO) mice were fear conditioned with 1 trial, 2 trials, or 4 trials. All mice learned both contextual (hippocampus-dependent) and cued (hippocampus-independent) fear conditioning but for contextual fear conditioning only, the JNK1 KO mice did not show higher levels of learning with increased trials. That is, WT mice showed a significant linear increase in contextual fear conditioning as training trials increased from 1 to 2 to 4 trials whereas KO mice showed the same level of contextual fear conditioning as WT mice for 1 trial training but did not have increased levels of contextual fear conditioning with additional trials. These data suggest that JNK1 may not be critical for learning but when higher levels of hippocampus-dependent learning occur, JNK1 signaling is recruited and is necessary for stronger hippocampus-dependent memory formation. Copyright © 2014 Elsevier Inc. All rights reserved.

  15. Global and Seasonal Scintillation Morphology in the Equatorial Region Derived from ROCSAT-1 In-situ Data

    Directory of Open Access Journals (Sweden)

    Yen-Hung Liu

    2012-01-01

    Full Text Available The global/seasonal distributions of the scintillation occurrence rate are obtained from the in-situ density measurement of the ROCSAT-1 using a modified procedure reported by Wernik et al. (2007. A least-squares curve fitting in the optimal trust region is used to obtain the spectral slope for the density irregularity structure and the outer scale of the scintillation. The distribution of the S4 index for the weak scintillation (S4 < 0.3 is almost identical to that of the equatorial irregularity distribution reported in the literature. However, as the scintillation becomes stronger (0.3 < S4 < 0.6, the latitudinal distribution moves to the equatorial ionization anomaly (EIA region. In addition, the distributions of the outer scale values that are useful for the study of the physical evolution of the irregularity structure are also obtained. The occurrence distribution of scintillation activity with several parameters such as dip-latitude, longitude, local time, solar activity, and geomagnetic activity during different seasons are presented and discussed in this paper.

  16. A Protein Data Bank survey reveals shortening of intermolecular hydrogen bonds in ligand-protein complexes when a halogenated ligand is an H-bond donor.

    Directory of Open Access Journals (Sweden)

    Jarosław Poznański

    Full Text Available Halogen bonding in ligand-protein complexes is currently widely exploited, e.g. in drug design or supramolecular chemistry. But little attention has been directed to other effects that may result from replacement of a hydrogen by a strongly electronegative halogen. Analysis of almost 30000 hydrogen bonds between protein and ligand demonstrates that the length of a hydrogen bond depends on the type of donor-acceptor pair. Interestingly, lengths of hydrogen bonds between a protein and a halogenated ligand are visibly shorter than those estimated for the same family of proteins in complexes with non-halogenated ligands. Taking into account the effect of halogenation on hydrogen bonding is thus important when evaluating structural and/or energetic parameters of ligand-protein complexes. All these observations are consistent with the concept that halogenation increases the acidity of the proximal amino/imino/hydroxyl groups and thus makes them better, i.e. stronger, H-bond donors.

  17. A Protein Data Bank survey reveals shortening of intermolecular hydrogen bonds in ligand-protein complexes when a halogenated ligand is an H-bond donor.

    Science.gov (United States)

    Poznański, Jarosław; Poznańska, Anna; Shugar, David

    2014-01-01

    Halogen bonding in ligand-protein complexes is currently widely exploited, e.g. in drug design or supramolecular chemistry. But little attention has been directed to other effects that may result from replacement of a hydrogen by a strongly electronegative halogen. Analysis of almost 30000 hydrogen bonds between protein and ligand demonstrates that the length of a hydrogen bond depends on the type of donor-acceptor pair. Interestingly, lengths of hydrogen bonds between a protein and a halogenated ligand are visibly shorter than those estimated for the same family of proteins in complexes with non-halogenated ligands. Taking into account the effect of halogenation on hydrogen bonding is thus important when evaluating structural and/or energetic parameters of ligand-protein complexes. All these observations are consistent with the concept that halogenation increases the acidity of the proximal amino/imino/hydroxyl groups and thus makes them better, i.e. stronger, H-bond donors.

  18. Sterically demanding iminopyridine ligands

    NARCIS (Netherlands)

    Irrgang, Torsten; Keller, Sandra; Maisel, Heidi; Kretschmer, Winfried; Kempe, Rhett

    Two sterically demanding iminopyridine ligands, (2,6-diisopropylphenyl)[6-(2,4,6-triisopropylphenyl)pyridin-2-ylmeth- ylene]amine and (2,6-diisopropylphenyl)]6-(2,6-dimethylphenyl)pyridin-2-ylmethylene]amine, were prepared by a two-step process: first, condensation of 6-bromopyridine-2-carbaldehyde

  19. Ligand close packing and the geometry of the fluorides of the nonmetals of periods 3, 4, and 5.

    Science.gov (United States)

    Robinson, E A; Gillespie, R J

    2003-06-16

    This paper discusses the geometry of the fluorides of the nonmetals of periods 3, 4, and 5 in terms of the ligand close packing (LCP) model according to which molecular geometry is determined primarily by ligand-ligand repulsions (Pauli closed shell repulsions) rather than by the bonding and lone pair Pauli repulsions of the VSEPR model. The LCP model becomes the dominant factor in determing geometry when the ligands are sufficiently crowded that they may be regarded as essentially incompressible. Ligand close packing is a modification of the VSEPR model in which ligand-ligand repulsion (Pauli closed shell repulsion) is given more emphasis than bonding and nonbonding electron pair Pauli repulsion. The nonmetals of period 3 are large enough to form octahedral six coordinated molecules in which the ligands are close packed. The larger nonmetals of period 4 also have a maximum coordination number of six and an octahedral geometry although the ligands are not close packed. Ligand radii derived from the interligand distances in the molecules of period 3 depend only on the charge of the fluorine ligands and are consistent with the previously derived radii obtained from the fluorides of the close packed tetrahedral molecules of the period 2 elements. Although the ligands in the molecules of the period 4 nonmetals are not close packed, these elements are not large enough to form molecules with a higher coordination number. However, the larger period 5 nonmetals may have coordination numbers of seven and eight. The seven coordinated molecules have a pentagonal bipyramidal geometry in which the equatorial ligands are close packed. The eight coordinated molecules have a square antiprism geometry, which is not a close packed geometry although the fluorine interligand distances are only a little larger than expected for close packing. The difference between the axial and equatorial bond lengths in the trigonal bipyramidal pentafluorides and the pentagonal bipyramidal

  20. Nonlinearly coupled dynamics of irregularities in the equatorial electrojet

    International Nuclear Information System (INIS)

    Atul, J.K.; Sarkar, S.; Singh, S.K.

    2016-01-01

    Kinetic wave description is used to study the nonlinear influence of background Farley Buneman (FB) modes on the Gradient Drift (GD) modes in the equatorial electrojet ionosphere. The dominant nonlinearity is mediated through the electron flux term in the governing fluid equation which further invokes a turbulent current into the system. Electron dynamics reveals the modification in electron collision frequency and inhomogeneity scale length. It is seen that the propagation and growth rate of GD modes get modified by the background FB modes. Also, a new quasimode gets excited through the quadratic dispersion relation. Physical significance of coupled dynamics between the participating modes is also discussed. - Highlights: • Nonlinear influence of Farley Buneman mode on the Gradient drift mode, is investigated. • Electron collision frequency and density gradient scale length get modified. • A new quasimode gets excited due to the competition between these modes. • It seems to be important for modelling of Equatorial Electrojet current system.

  1. Industrial concessions, fires and air pollution in Equatorial Asia

    Science.gov (United States)

    Spracklen, D. V.; Reddington, C. L.; Gaveau, D. L. A.

    2015-09-01

    Forest and peatland fires in Indonesia emit large quantities of smoke leading to poor air quality across Equatorial Asia. Marlier et al (2015 Environ. Res. Lett. 10 085005) explore the contribution of fires occurring on oil palm, timber (wood pulp and paper) and natural forest logging concessions to smoke emissions and exposure of human populations to the resulting air pollution. They find that one third of the population exposure to smoke across Equatorial Asia is caused by fires in oil palm and timber concessions in Sumatra and Kalimantan. Logging concessions have substantially lower fire emissions, and contribute less to air quality degradation. This represents a compelling justification to prevent reclassification of logging concessions into oil palm or timber concessions after logging. This can be achieved by including logged forests in the Indonesian moratorium on new plantations in forested areas.

  2. Ongoing Analysis of Jupiter's Equatorial Hotspots and Plumes from Cassini

    Science.gov (United States)

    Choi, D. S.; Showmwn, A. P.; Vasavada, A. R.; Simon-Miller, A. A.

    2012-01-01

    We present updated results from our ongoing analysis of Cassini observations of Jupiter's equatorial meteorology. For two months preceding the spacecraft's closest approach of the planet, the ISS instrument onboard Cassini regularly imaged the atmosphere of Jupiter. We created time-lapse movies from this period that show the complex activity and interactions of the equatorial atmosphere. During this period, hot spots exhibited significant variations in size and shape over timescales of days and weeks. Some of these changes appear to be a result of interactions with passing vortex systems in adjacent latitudes. Strong anticyclonic gyres to the southeast of the dark areas converge with flow from the west and appear to circulate into a hot spot at its southwestern corner.

  3. Equatorial enhancement of the nighttime OH mesospheric infrared airglow

    International Nuclear Information System (INIS)

    Baker, D J; Thurgood, B K; Harrison, W K; Mlynczak, M G; Russell, J M

    2007-01-01

    Global measurements of the hydroxyl mesospheric airglow over an extended period of time have been made possible by the NASA SABER infrared sensor aboard the TIMED satellite which has been functioning since December of 2001. The orbital mission has continued over a significant portion of a solar cycle. Experimental data from SABER for several years have exhibited equatorial enhancements of the nighttime mesospheric OH (Δv=2) airglow layer consistent with the high average diurnal solar flux. The brightening of the OH airglow typically means more H+O 3 is being reacted. At both the spring and autumn seasonal equinoxes when the equatorial solar UV irradiance mean is greatest, the peak volume emission rate (VER) of the nighttime Meinel infrared airglow typically appears to be both significantly brighter plus lower in altitude by several kilometres at low latitudes compared with midlatitude findings

  4. Meteorology of Jupiter's Equatorial Hot Spots and Plumes from Cassini

    Science.gov (United States)

    Choi, David Sanghun; Showman, Adam P.; Vasavada, Ashwin R.; Simon-Miller, Amy A.

    2013-01-01

    We present an updated analysis of Jupiter's equatorial meteorology from Cassini observations. For two months preceding the spacecraft's closest approach, the Imaging Science Subsystem (ISS) onboard regularly imaged the atmosphere. We created time-lapse movies from this period in order to analyze the dynamics of equatorial hot spots and their interactions with adjacent latitudes. Hot spots are relatively cloud-free regions that emit strongly at 5 lm; improved knowledge of these features is crucial for fully understanding Galileo probe measurements taken during its descent through one. Hot spots are quasistable, rectangular dark areas on visible-wavelength images, with defined eastern edges that sharply contrast with surrounding clouds, but diffuse western edges serving as nebulous boundaries with adjacent equatorial plumes. Hot spots exhibit significant variations in size and shape over timescales of days and weeks. Some of these changes correspond with passing vortex systems from adjacent latitudes interacting with hot spots. Strong anticyclonic gyres present to the south and southeast of the dark areas appear to circulate into hot spots. Impressive, bright white plumes occupy spaces in between hot spots. Compact cirrus-like 'scooter' clouds flow rapidly through the plumes before disappearing within the dark areas. These clouds travel at 150-200 m/s, much faster than the 100 m/s hot spot and plume drift speed. This raises the possibility that the scooter clouds may be more illustrative of the actual jet stream speed at these latitudes. Most previously published zonal wind profiles represent the drift speed of the hot spots at their latitude from pattern matching of the entire longitudinal image strip. If a downward branch of an equatorially-trapped Rossby wave controls the overall appearance of hot spots, however, the westward phase velocity of the wave leads to underestimates of the true jet stream speed.

  5. Equatorial electrojet in the south Atlantic anomaly region

    Indian Academy of Sciences (India)

    Features of the equatorial electrojet are studied at Sao Luiz (2.6°S, 44.2°W, inclination −0.25°) in eastern Brazil and Sikasso (11.3°N, 5.7°W, inclination 0.1°) in the western African sector. The stations are situated on either side of the lowest magnetic field intensity in the region of rapid changes in the declination. The daily ...

  6. Equatorial noise emissions with quasiperiodic modulation of wave intensity

    Czech Academy of Sciences Publication Activity Database

    Němec, F.; Santolík, Ondřej; Hrbáčková, Zuzana; Pickett, J. S.; Cornilleau-Wehrlin, N.

    2015-01-01

    Roč. 120, č. 4 (2015), s. 2649-2661 ISSN 2169-9380 R&D Projects: GA MŠk(CZ) LH11122 Institutional support: RVO:68378289 Keywords : equatorial noise * magnetosonic waves * quasiperiodic modulation Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 3.318, year: 2015 http://onlinelibrary.wiley.com/doi/10.1002/2014JA020816/full

  7. Climatic Variation at Thumba Equatorial Rocket Launching Station, India

    OpenAIRE

    K. V. S. Namboodiri; P. K. Dileep; Koshy Mammen

    2013-01-01

    Long-term (45 years) diversified surface meteorological records from Thumba Equatorial Rocket Launching Station (TERLS), India, were collected and analysed to study the long-term changes in the overall climatology, climatology pertained to a particular observational time, mean daily climatology in temperature, inter-annual variability in temperature, interannual variability in surface pressure, and rainfall for the main Indian seasons—South West and North East monsoons and inter-annual mean m...

  8. Analysis of macromolecules, ligands and macromolecule-ligand complexes

    Science.gov (United States)

    Von Dreele, Robert B [Los Alamos, NM

    2008-12-23

    A method for determining atomic level structures of macromolecule-ligand complexes through high-resolution powder diffraction analysis and a method for providing suitable microcrystalline powder for diffraction analysis are provided. In one embodiment, powder diffraction data is collected from samples of polycrystalline macromolecule and macromolecule-ligand complex and the refined structure of the macromolecule is used as an approximate model for a combined Rietveld and stereochemical restraint refinement of the macromolecule-ligand complex. A difference Fourier map is calculated and the ligand position and points of interaction between the atoms of the macromolecule and the atoms of the ligand can be deduced and visualized. A suitable polycrystalline sample of macromolecule-ligand complex can be produced by physically agitating a mixture of lyophilized macromolecule, ligand and a solvent.

  9. Modulation of precipitation over West Africa by equatorial waves

    Science.gov (United States)

    Schlüter, Andreas; van der Linden, Roderick; Vogel, Peter; Fink, Andreas H.; Knippertz, Peter

    2017-04-01

    Equatorial waves can couple with deep convection and thus modulate rainfall on the synoptic timescale throughout the tropics. Until now, however, no comparative study of the influence of all the different wave types on precipitation has been performed specifically for West Africa. To fill this gap, the following wave types were analyzed for the pre-/post- and full monsoon season (April to October): (1) the Madden-Julian Oscillation (MJO), (2) Kelvin waves, (3) equatorial Rossby waves, (4) eastward-propagating inertia gravity waves, (5) mixed Rossby-gravity waves and (6) tropical disturbances/African Easterly Waves. The different wave types were filtered in the wavenumber-frequency spectrum of outgoing longwave radiation. Eight different wave phases were defined from a phase diagram that can be calculated from the time-derivative of the filtered wave signal. Subsequently, composites of dynamical and thermodynamical fields for each wave phase of the different wave types were plotted using the ERA Interim reanalysis from the European Centre for Medium-Range Weather Forecasts. This way the propagation of the wave can be depicted. All aforementioned wave types, except the fast eastward-propagating inertia gravity wave, show consistent and significant influence on West African rainfall. The influence of the waves can be seen far into the subtropics for some wave types. The expected theoretical structure is confirmed by the analysis of upper- and lower-level divergence, wind and geopotential height. An interaction between the tropical and extratropical regime appears to occur for the MJO and equatorial Rossby waves. The mechanism involved in this interaction, however, is not fully understood. Composites of low-level wind shear, convective available potential energy and mid-level moisture are used to analyze whether waves create favorable conditions for the organization of convection. Additionally, the source regions of moisture were identified using moisture fields and

  10. Radiobiology with DNA ligands

    International Nuclear Information System (INIS)

    Weinreich, R.; Argentini, M.; Guenther, I.; Koziorowski, J.; Larsson, B.; Nievergelt-Egido, M.C.; Salt, C.; Wyer, L.; Dos Santos, D.F.; Hansen, H.J.

    1997-01-01

    The paper deals with the following topics: labelling of DNA ligands and other tumour-affinic compounds with 4.15-d 124 I, radiotoxicity of Hoechst 33258 and 33342 and of iodinated Hoechst 33258 in cell cultures, preparation of 76 Br-, 123 I-, and 221 At-labelled 5-halo-2'-deoxyuridine, chemical syntheses of boron derivatives of Hoechst 33258.III., Gadolinium neutron capture therapy

  11. Therapeutic androgen receptor ligands

    Science.gov (United States)

    Allan, George F.; Sui, Zhihua

    2003-01-01

    In the past several years, the concept of tissue-selective nuclear receptor ligands has emerged. This concept has come to fruition with estrogens, with the successful marketing of drugs such as raloxifene. The discovery of raloxifene and other selective estrogen receptor modulators (SERMs) has raised the possibility of generating selective compounds for other pathways, including androgens (that is, selective androgen receptor modulators, or SARMs). PMID:16604181

  12. How the biotin–streptavidin interaction was made even stronger: investigation via crystallography and a chimaeric tetramer

    Science.gov (United States)

    Chivers, Claire E.; Koner, Apurba L.; Lowe, Edward D.; Howarth, Mark

    2011-01-01

    The interaction between SA (streptavidin) and biotin is one of the strongest non-covalent interactions in Nature. SA is a widely used tool and a paradigm for protein–ligand interactions. We previously developed a SA mutant, termed Tr (traptavidin), possessing a 10-fold lower off-rate for biotin, with increased mechanical and thermal stability. In the present study, we determined the crystal structures of apo-Tr and biotin–Tr at 1.5 Å resolution. In apo-SA the loop (L3/4), near biotin's valeryl tail, is typically disordered and open, but closes upon biotin binding. In contrast, L3/4 was shut in both apo-Tr and biotin–Tr. The reduced flexibility of L3/4 and decreased conformational change on biotin binding provide an explanation for Tr's reduced biotin off- and on-rates. L3/4 includes Ser45, which forms a hydrogen bond to biotin consistently in Tr, but erratically in SA. Reduced breakage of the biotin–Ser45 hydrogen bond in Tr is likely to inhibit the initiating event in biotin's dissociation pathway. We generated a Tr with a single biotin-binding site rather than four, which showed a simi-larly low off-rate, demonstrating that Tr's low off-rate was governed by intrasubunit effects. Understanding the structural features of this tenacious interaction may assist the design of even stronger affinity tags and inhibitors. PMID:21241253

  13. Crystal structure of di-μ-chlorido-bis[dichloridobis(methanol-κOiridium(III] dihydrate: a surprisingly simple chloridoiridium(III dinuclear complex with methanol ligands

    Directory of Open Access Journals (Sweden)

    Joseph S. Merola

    2015-05-01

    Full Text Available The reaction between IrCl3·xH2O in methanol led to the formation of small amounts of the title compound, [Ir2Cl6(CH3OH4]·2H2O, which consists of two IrCl4O2 octahedra sharing an edge via chloride bridges. The molecule lies across an inversion center. Each octahedron can be envisioned as being comprised of four chloride ligands in the equatorial plane with methanol ligands in the axial positions. A lattice water molecule is strongly hydrogen-bonded to the coordinating methanol ligands and weak interactions with coordinating chloride ligands lead to the formation of a three-dimensional network. This is a surprising structure given that, while many reactions of iridium chloride hydrate are carried out in alcoholic solvents, especially methanol and ethanol, this is the first structure of a chloridoiridium compound with only methanol ligands.

  14. Discovery Of A Rossby Wave In Jupiter's South Equatorial Region

    Science.gov (United States)

    Simon-Miller, Amy A.; Choi, D. S.; Rogers, J. H.; Gierasch, P. J.

    2012-01-01

    A detailed study of the chevron-shaped dark spots on the strong southern equatorial wind jet near 7.5 deg S planetographic latitude shows variations in velocity with longitude and time. The chevrons move with velocities near the maximum wind jet velocity of approx.140 m/s, as deduced by the history of velocities at this latitude and the magnitude of the symmetric wind jet near 7 deg N latitude. Their repetitive nature is consistent with an inertia-gravity wave (n = 75-100) with phase speed up to 25 m/s, relative to the local flow, but the identity of this wave mode is not well constrained. However, high spatial resolution movies from Cassini images show that the chevrons oscillate in latitude with a approx.7-day period. This oscillating motion has a wavelength of approx.20 deg and a speed of approx.100 m/s, following a pattern similar to that seen in the Rossby wave plumes of the North Equatorial Zone, and possibly reinforced by it, though they are not perfectly in phase. The transient anticyclonic South Equatorial Disturbance (SED) may be a similar wave feature, but moves at slower velocity. All data show chevron latitude variability, but it is unclear if this Rossby wave is present during other epochs, without time series movies that fully delineate it. In the presence of multiple wave modes, the difference in dominant cloud appearance between 7 deg N and 7.5 deg S may be due to the presence of the Great Red Spot, either through changes in stratification and stability or by acting as a wave boundary.

  15. Regulation of primary productivity rate in the equatorial Pacific

    Energy Technology Data Exchange (ETDEWEB)

    Barber, R.T. (Duke Univ. Marine Lab., Beaufort, NC (United States)); Chavez, F.P. (Monterey Bay Aquarium Research Inst., Pacific Grove, CA (United States))

    1991-12-01

    Analysis of the Chl-specific rate of primary productivity (P{sup B}) as a function of subsurface nutrient concentration at >300 equatorial stations provides an answer to the question: What processes regulate primary productivity rate in the high-nutrient, low-chlorophyll waters of the equatorial Pacific In the western Pacific where there is a gradient in 60-m (NO{sub 3}) from 0 to {approximately}12 {mu}M, the productivity rate is a linear function of nutrient concentration; in the eastern Pacific where the gradient is from 12 to 28 {mu}M, the productivity rate is independent of nutrient concentration and limited to {approximately}36 mg C(mg Chl){sup {minus}1} d{sup {minus}1}, or a mean euphotic zone C-specific growth rate ({mu}) of 0.47 d{sup {minus}1}. However, rates downstream of the Galapagos Islands are not limited; they are 46.4 mg C(mg Chl){sup {minus}1} d{sup {minus}1} and {mu} = 0.57 d{sup {minus}1}, very close to the predicted nutrient-regulated rates in the absence of other limitation. This pattern of rate regulation can be accounted for by a combination of eolian Fe, subsurface nutrients, and sedimentary Fe derived from the Galapagos platform. In the low-nutrient western Pacific the eolian supply of Fe is adequate to allow productivity rate to be set by subsurface nutrient concentration. In the nutrient-rich easter equatorial region eolian Fe is inadequate to support productivity rates proportional to the higher nutrient concentrations, so in this region eolian Fe is rate limiting. Around the Galapagos Islands productivity rates reach levels consistent with nutrient concentrations; sedimentary Fe from the Galapagos platform seems adequate to support increased nutrient-regulated productivity rates in this region.

  16. Regulation of primary productivity rate in the equatorial Pacific

    International Nuclear Information System (INIS)

    Barber, R.T.; Chavez, F.P.

    1991-01-01

    Analysis of the Chl-specific rate of primary productivity (P B ) as a function of subsurface nutrient concentration at >300 equatorial stations provides an answer to the question: What processes regulate primary productivity rate in the high-nutrient, low-chlorophyll waters of the equatorial Pacific? In the western Pacific where there is a gradient in 60-m [NO 3 ] from 0 to ∼12 μM, the productivity rate is a linear function of nutrient concentration; in the eastern Pacific where the gradient is from 12 to 28 μM, the productivity rate is independent of nutrient concentration and limited to ∼36 mg C(mg Chl) -1 d -1 , or a mean euphotic zone C-specific growth rate (μ) of 0.47 d -1 . However, rates downstream of the Galapagos Islands are not limited; they are 46.4 mg C(mg Chl) -1 d -1 and μ = 0.57 d -1 , very close to the predicted nutrient-regulated rates in the absence of other limitation. This pattern of rate regulation can be accounted for by a combination of eolian Fe, subsurface nutrients, and sedimentary Fe derived from the Galapagos platform. In the low-nutrient western Pacific the eolian supply of Fe is adequate to allow productivity rate to be set by subsurface nutrient concentration. In the nutrient-rich easter equatorial region eolian Fe is inadequate to support productivity rates proportional to the higher nutrient concentrations, so in this region eolian Fe is rate limiting. Around the Galapagos Islands productivity rates reach levels consistent with nutrient concentrations; sedimentary Fe from the Galapagos platform seems adequate to support increased nutrient-regulated productivity rates in this region

  17. High resolution 2-D maps of OI 630.0 nm thermospheric dayglow from equatorial latitudes

    Directory of Open Access Journals (Sweden)

    D. Pallam Raju

    1998-08-01

    Full Text Available The first-ever high resolution 2-D maps of OI 630.0 nm dayglow obtained from equatorial latitudes clearly reveal the movement as a large-scale feature of the equatorial ionization anomaly (EIA. These also show the presence of wave-like features classified as gravity waves presumably originating at the crest of the EIA, similar to the equatorial electrojet acting as a source of these waves. These results are presented and discussed.Key words. Atmospheric composition and structure (Airglow and aurora · Ionosphere (Equatorial ionosphere; Instruments and techniques.

  18. High resolution 2-D maps of OI 630.0 nm thermospheric dayglow from equatorial latitudes

    Directory of Open Access Journals (Sweden)

    D. Pallam Raju

    Full Text Available The first-ever high resolution 2-D maps of OI 630.0 nm dayglow obtained from equatorial latitudes clearly reveal the movement as a large-scale feature of the equatorial ionization anomaly (EIA. These also show the presence of wave-like features classified as gravity waves presumably originating at the crest of the EIA, similar to the equatorial electrojet acting as a source of these waves. These results are presented and discussed.

    Key words. Atmospheric composition and structure (Airglow and aurora · Ionosphere (Equatorial ionosphere; Instruments and techniques.

  19. Bexarotene ligand pharmaceuticals.

    Science.gov (United States)

    Hurst, R E

    2000-12-01

    Bexarotene (LGD-1069), from Ligand, was the first retinoid X receptor (RXR)-selective, antitumor retinoid to enter clinical trials. The company launched the drug for the treatment of cutaneous T-cell lymphoma (CTCL), as Targretin capsules, in the US in January 2000 [359023]. The company filed an NDA for Targretin capsules in June 1999, and for topical gel in December 1999 [329011], [349982] specifically for once-daily oral administration for the treatment of patients with early-stage CTCL who have not tolerated other therapies, patients with refractory or persistent early stage CTCL and patients with refractory advanced stage CTCL. The FDA approved Targretin capsules at the end of December 1999 for once-daily oral treatment of all stages of CTCL in patients refractory to at least one prior systemic therapy, at an initial dose of 300 mg/m2/day. After an NDA was submitted in December 1999 for Targretin gel, the drug received Priority Review status for use as a treatment of cutaneous lesions in patients with stage IA, IB or IIA CTCL [354836]. The FDA issued an approvable letter in June 2000, and granted marketing clearance for CTCL in the same month [370687], [372768], [372769], [373279]. Ligand had received Orphan Drug designation for this indication [329011]. At the request of the FDA, Ligand agreed to carry out certain post-approval phase IV and pharmacokinetic studies [351604]. The company filed an MAA with the EMEA for Targretin Capsules to treat lymphoma in November 1999 [348944]. The NDA for Targretin gel is based on a multicenter phase III trial that was conducted in the US, Canada, Europe and Australia involving 50 patients and a multicenter phase I/II clinical program involving 67 patients. Targretin gel was evaluated for the treatment of patients with early stage CTCL (IA-IIA) who were refractory to, intolerant to, or reached a response plateau for at least 6 months on at least two prior therapies. Efficacy results exceeded the protocol-defined response

  20. Spatiotemporal variability and propagation of equatorial noise observed by Cluster

    Czech Academy of Sciences Publication Activity Database

    Santolík, Ondřej; Pickett, J. S.; Gurnett, D. A.; Maksimovic, M.; Cornilleau-Wehrlin, N.

    2002-01-01

    Roč. 107, A12, 1495 (2002), s. SMP 43-1-43-8, doi: 10.1029/2001JA009159 ISSN 0148-0227 R&D Projects: GA ČR GA205/01/1064 Grant - others:NASA(US) NAG5-9974 Institutional research plan: CEZ:AV0Z3042911; CEZ:MSM 113200004 Keywords : outer plasmasphere * proton-cyclotron frequency * electromagnetic equatorial noise Subject RIV: DG - Athmosphere Sciences, Meteorology Impact factor: 2.245, year: 2002

  1. Provisional hourly values of equatorial Dst for 1971

    Science.gov (United States)

    Sugiura, M.; Poros, D. J.

    1972-01-01

    Tables and plots of provisional hourly values of the equatorial Dst index for 1971 are given, a table of daily mean Dst values for 1971 is also provided. The base line values for the four observatories, Hermanus, Kakioka, Honolulu, and San Juan, were obtained from extrapolations using the coefficients for the secular variations determined for the previous years. Examining the Dst values for quiet days, the base lines so determined appear to be slightly low, so that the Dst index for quiet periods tends to be high.

  2. Vertical Rise Velocity of Equatorial Plasma Bubbles Estimated from Equatorial Atmosphere Radar Observations and High-Resolution Bubble Model Simulations

    Science.gov (United States)

    Yokoyama, T.; Ajith, K. K.; Yamamoto, M.; Niranjan, K.

    2017-12-01

    Equatorial plasma bubble (EPB) is a well-known phenomenon in the equatorial ionospheric F region. As it causes severe scintillation in the amplitude and phase of radio signals, it is important to understand and forecast the occurrence of EPBs from a space weather point of view. The development of EPBs is presently believed as an evolution of the generalized Rayleigh-Taylor instability. We have already developed a 3D high-resolution bubble (HIRB) model with a grid spacing of as small as 1 km and presented nonlinear growth of EPBs which shows very turbulent internal structures such as bifurcation and pinching. As EPBs have field-aligned structures, the latitude range that is affected by EPBs depends on the apex altitude of EPBs over the dip equator. However, it was not easy to observe the apex altitude and vertical rise velocity of EPBs. Equatorial Atmosphere Radar (EAR) in Indonesia is capable of steering radar beams quickly so that the growth phase of EPBs can be captured clearly. The vertical rise velocities of the EPBs observed around the midnight hours are significantly smaller compared to those observed in postsunset hours. Further, the vertical growth of the EPBs around midnight hours ceases at relatively lower altitudes, whereas the majority of EPBs at postsunset hours found to have grown beyond the maximum detectable altitude of the EAR. The HIRB model with varying background conditions are employed to investigate the possible factors that control the vertical rise velocity and maximum attainable altitudes of EPBs. The estimated rise velocities from EAR observations at both postsunset and midnight hours are, in general, consistent with the nonlinear evolution of EPBs from the HIRB model.

  3. Neutronic analysis of the Diagnostic Equatorial Ports in ITER

    Energy Technology Data Exchange (ETDEWEB)

    Suarez, Alejandro [ITER Organization, Route de Vinon sur Verdon, 13115 Saint Paul Lez Durance (France); Bertalot, Luciano, E-mail: luciano.bertalot@iter.org [ITER Organization, Route de Vinon sur Verdon, 13115 Saint Paul Lez Durance (France); Maquet, Philippe; Pitcher, Charles Spencer; Portales, Mickael [ITER Organization, Route de Vinon sur Verdon, 13115 Saint Paul Lez Durance (France); Serikov, Arkady [Karlsruhe Institute of Technology KIT, 76344 Eggenstein-Leopoldshafen (Germany); Udintsev, Victor; Walsh, Michael [ITER Organization, Route de Vinon sur Verdon, 13115 Saint Paul Lez Durance (France)

    2015-10-15

    Highlights: • Reduction of the streaming around Equatorial Ports. • Solutions for the mitigation of narrow gap streaming. • Importance of the environment and the radiation cross talk. - Abstract: The Diagnostic Port Plugs provide an infrastructure for integrating the diagnostics necessary to operate the machine, while withstanding the nuclear and mechanical loads. They have to provide neutron shielding in order to ensure accessibility to the Port Interspace (PI) region for maintenance operations. This report is about the study to mitigate the ITER Shutdown Dose Rate in Port Interspace. This is a strong design driver for the Equatorial Port Plugs (EPPs) requiring a neutron attenuation of 7 orders of magnitude while maintaining the weight limit. To achieve this challenging task, the design has evolved to an improved double labyrinth configuration with welded shims at the back of the EPP to reduce the gap with the Vacuum Vessel Port Extension. This proved to be very successful for this task. Neutron stoppers have been placed after the gaps necessary for the insertion of the Diagnostic Shielding Modules (DSMs) housed inside the EPP. Effort was also placed in the further development of the DSMs. The latest design relies on a stainless steel structure and lightweight efficient neutron absorbing materials inside. Studies of cross talk with lower ports and the influence of the streaming through the blanket area are presented to give the status of the radiation environment in the Port Interspace region and their contribution to the Shutdown Dose Rate (SDR).

  4. Semidiurnal internal tide incoherence in the equatorial Pacific

    Science.gov (United States)

    Buijsman, Maarten C.; Arbic, Brian K.; Richman, James G.; Shriver, Jay F.; Wallcraft, Alan J.; Zamudio, Luis

    2017-07-01

    The jets in the equatorial Pacific Ocean of a realistically forced global circulation model with a horizontal resolution of 1/12.5° cause a strong loss of phase coherence in semidiurnal internal tides that propagate equatorward from the French Polynesian Islands and Hawaii. This loss of coherence is quantified with a baroclinic energy analysis, in which the semidiurnal-band terms are separated into coherent, incoherent, and cross terms. For time scales longer than a year, the coherent energy flux approaches zero values at the equator, while the total flux is ˜500 W/m. The time variability of the incoherent energy flux is compared with the internal-tide travel-time variability, which is based on along-beam integrated phase speeds computed with the Taylor-Goldstein equation. The variability of monthly mean Taylor-Goldstein phase speeds agrees well with the phase speed variability inferred from steric sea surface height phases extracted with a plane-wave fit technique. On monthly time scales, the loss of phase coherence in the equatorward beams from the French Polynesian Islands is attributed to the time variability in the vertically sheared background flow associated with the jets and tropical instability waves. On an annual time scale, the effect of stratification variability is of equal or greater importance than the shear variability is to the loss of coherence. In the model simulations, low-frequency equatorial jets do not noticeably enhance the dissipation of the internal tide, but merely decohere and scatter it.

  5. Intense equatorial flux spots on the surface of Earth's core

    Science.gov (United States)

    Jackson, A.

    2003-04-01

    A vast number of vector measurements of the Earth's magnetic field have recently become available from the satellite Oersted, currently in orbit monitoring the core magnetic field. In this presentation I will present new maps of the Earth's magnetic field at the surface of the fluid core derived from these satellite data which show intense flux spots in equatorial regions; the images are derived using a maximum entropy technique which is capable of reconstructing images with high dynamic range more precisely than conventional techniques. The intensity of these features is unusually large - they are comparable to high-latitude flux patches near the poles, previously identified as the major component of the dynamo field. A comparison with sunspots is tempting, though they are probably not associated with expulsion of toroidal magnetic field as is the case for the sun. Indeed, the tendency for pairing of these spots to the north and south of the geographical equator suggests they might be associated with the tops of so-called `Taylor columns' (indicative of the dominance of the rotation of the Earth) which have previously been suggested to be associated with the four high-latitude flux patches near the poles. Equatorially-trapped waves are known to exist in theory, and a correct interpretation of these features might lead to constraints on the strength of the hidden toroidal magnetic field within the Earth, as well as constraints on other physical regimes.

  6. Longitudinal Variability of Equatorial Electrodynamics and Density Irregularities

    Science.gov (United States)

    Yizengaw, E.; Doherty, P.

    2017-12-01

    The longitudinal variability of equatorial electrodynamics or scintillations has not been thoroughly investigated due to the lack of ground-based instruments that track the temporal variation of electrodynamics at different longitudes. Thus, study of longitudinal variability of electrodynamics has been possible only using in situ observations. In this paper, for the first time, we present the longitudinal variability of the nightside equatorial electrodynamics signatures that may be responsible for the formation of bubbles and scintillation activities. It is well known that the H-component geomagnetic field at low latitudes shows clear signatures for external currents during dayside and nightside. Thus, by removing Sq and ring currents contribution, it is possible to eliminate the gradual drift of the background field. Conspicuously, the residual geomagnetic field signature shows interestingly well-defined increase in ΔH during nightside, indicating the existence of eastward electric field at night. It is also well known that the Pedersen conductivity exhibits a large gradient across the sunset terminator due to large E-region conductivity on dayside compared to conductivity on nightside. This causes the positive charges to be accumulated at the terminator followed by the formation of divergent electric field at the terminator, which is eastward and maps along the equipotential field lines to F-region. In this paper, we present the longitudinal variability of the nightside divergent eastward electric field using the longitudinal chain of AMBER magnetometer network.

  7. Study of the equatorial Atlantic Ocean mixing layer using a one-dimensional turbulence model

    Directory of Open Access Journals (Sweden)

    Udo Tersiano Skielka

    2010-06-01

    Full Text Available The General Ocean Turbulence Model (GOTM is applied to the diagnostic turbulence field of the mixing layer (ML over the equatorial region of the Atlantic Ocean. Two situations were investigated: rainy and dry seasons, defined, respectively, by the presence of the intertropical convergence zone and by its northward displacement. Simulations were carried out using data from a PIRATA buoy located on the equator at 23º W to compute surface turbulent fluxes and from the NASA/GEWEX Surface Radiation Budget Project to close the surface radiation balance. A data assimilation scheme was used as a surrogate for the physical effects not present in the one-dimensional model. In the rainy season, results show that the ML is shallower due to the weaker surface stress and stronger stable stratification; the maximum ML depth reached during this season is around 15 m, with an averaged diurnal variation of 7 m depth. In the dry season, the stronger surface stress and the enhanced surface heat balance components enable higher mechanical production of turbulent kinetic energy and, at night, the buoyancy acts also enhancing turbulence in the first meters of depth, characterizing a deeper ML, reaching around 60 m and presenting an average diurnal variation of 30 m.O modelo General Ocean Turbulence Model (GOTM é aplicado para diagnosticar o campo de turbulência da camada de mistura oceânica (CM na região equatorial do Oceano Atlântico. Foram investigadas as estações chuvosa e seca, definidas, respectivamente, pela presença da zona de convergência intertropical e pelo seu deslocamento para norte. Simulações foram realizadas usando dados da bóia PIRATA (0º, 23ºW para o cálculo dos fluxos turbulentos de superfície e dados do Projeto NASA/GEWEX Surface Radiation Budget para "fechar" o balanço de radiação na superfície. Um esquema para assimilação de dados foi usado para considerar os mecanismos físicos não representados pelo modelo unidimensional

  8. Changes in Equatorial Atlantic Ocean Thermohaline Circulation Across the Mid-Pleistocene Transition

    Science.gov (United States)

    Yehudai, M.; Kim, J.; Seguí, M. J.; Goldstein, S. L.; Pena, L. D.; Haynes, L.; Hoenisch, B.; Farmer, J. R.; Ford, H. L.; Raymo, M. E.; Bickert, T.

    2016-12-01

    The Mid-Pleistocene Transition (MPT) marked a change in the duration of glacial-interglacial cycles from 41 to 100kyr between 1.3-0.7 Ma. A recent study (Pena and Goldstein, Science, 2014) from the Southern Atlantic Ocean found evidence for major disruptions in the global thermohaline circulation (THC) between MIS 25-21 ( 950-850ka), which may have triggered intensified glacial periods and the onset of the 100 kyr cycles. We report new Nd isotope data on Fe-Mn oxide encrusted foraminifera and fish debris from ODP Site 926 (3.719N, 42.908W, 3598m) between 1.2-0.4 Ma, in order to evaluate changes in the THC in the equatorial Atlantic, through comparison with North and South Atlantic sites. The ODP 926 ɛNd values fall in-between those in the North Atlantic (DSDP 607) and South Atlantic (ODP 1088 and 1090) throughout the studied interval, consistent with mixing between northern and southern end-members, and supporting the interpretation that the data represent the THC signal at this site. Pre-MPT data show smaller glacial-interglacial differences compared to the greater post-MPT glacial-interglacial variability. As Pena and Goldstein (2014) observed in the South Atlantic, during MIS 23 at 900 ka, ɛNd values do not shift significantly toward North Atlantic more negative values, consistent with a weak THC through this critical weak interglacial. Comparing ODP 926 and DSDP 607 data, ɛNd values converge during most interglacial peaks (excepting MIS 23) and diverge otherwise. This observation indicates that northern-sourced water masses dominate the site during peak interglacials, and confirms that the THC has been strongest during peak interglacials throughout the studied interval. Otherwise, diverging ɛNd values indicate a stronger southern-source signal and weaker northern-source signal at the ODP 926 site. This confirms that there was an active but variable THC system before, during, and after the MPT, with stronger deep water export from the North Atlantic during

  9. Ligand Depot: a data warehouse for ligands bound to macromolecules.

    Science.gov (United States)

    Feng, Zukang; Chen, Li; Maddula, Himabindu; Akcan, Ozgur; Oughtred, Rose; Berman, Helen M; Westbrook, John

    2004-09-01

    Ligand Depot is an integrated data resource for finding information about small molecules bound to proteins and nucleic acids. The initial release (version 1.0, November, 2003) focuses on providing chemical and structural information for small molecules found as part of the structures deposited in the Protein Data Bank. Ligand Depot accepts keyword-based queries and also provides a graphical interface for performing chemical substructure searches. A wide variety of web resources that contain information on small molecules may also be accessed through Ligand Depot. Ligand Depot is available at http://ligand-depot.rutgers.edu/. Version 1.0 supports multiple operating systems including Windows, Unix, Linux and the Macintosh operating system. The current drawing tool works in Internet Explorer, Netscape and Mozilla on Windows, Unix and Linux.

  10. Neogene paleoceanography of the eastern equatorial Pacific based on the radiolarian record of IODP drill sites off Costa Rica

    Science.gov (United States)

    Sandoval, María. I.; Boltovskoy, Demetrio; Baxter, Alan T.; Baumgartner, Peter O.

    2017-03-01

    The Integrated Ocean Drilling Program (IODP) Expedition 344 drilled cores following a transect across the convergent margin off Costa Rica. Two of the five sites (U1381 and U1414) are the subject of the present study. Major radiolarian faunal breaks and characteristic species groups were defined with the aid of cluster analysis, nodal analysis, and discriminant analysis of principal components. A middle-late Miocene to Pleistocene age (radiolarian zones RN5 to RN16) was determined for the sites, which agrees with the nannofossil zonations and 40Ar/39Ar and tephra layers. Considering the northward movement of the Cocos plate (˜7.3 cm/yr), and a paleolatitude calculator, it is assumed that during the Miocene the two sites were located ˜1000 km to the southwest of their current position, slightly south of the equator. The radiolarian faunas retrieved were thus seemingly formed under the influence of different oceanic currents and sources of nutrients. Changes in the radiolarian assemblages at Site U1414 point at dissimilar environmental settings associated with the colder South Equatorial Current and the warmer Equatorial Countercurrent, as well as to coastal upwelling. These differences are best reflected by changes in the abundance of the morphotype Spongurus spp., with noticeably higher values during the Miocene, than in the Pliocene and the Pleistocene. Because Spongurus spp. is generally associated with cooler waters, these abundance variations (as well as those of several other species) suggest that during the Miocene the area had a stronger influence of colder waters than during younger periods. During the Pliocene and the lowermost Pleistocene, biogenic remains are scarce, presumably due to the terrigenous input, which could have diluted and affected the preservation of pelagic fossils, as well as to the displacement of the site to warmer waters. A typically tropical fauna characterized the Pleistocene, yet with widespread presence of colder water species

  11. Study of equatorial regions of Moon with the help of backscattering ...

    Indian Academy of Sciences (India)

    sensors are used for analyzing the equatorial region of the Moon (60. ◦. N to 60 ... In this paper we have discussed the scattering behaviour of lunar equatorial region where the value of. CPR >1. Studies .... Figure 1. Generic hybrid polarity architecture in which the transmitted field is circularly polarized (right or left), and the.

  12. Variability in the origins and pathways of Pacific Equatorial Undercurrent water

    NARCIS (Netherlands)

    Qin, Xuerong; Sen Gupta, Alex; Van Sebille, Erik

    2015-01-01

    The Pacific Equatorial Undercurrent (EUC) transports water originating from a number of distinct source regions, eastward across the Pacific Ocean. It is responsible for supplying nutrients to the productive eastern Equatorial Pacific Ocean. Of particular importance is the transport of iron by the

  13. A note on new indices for the equatorial Indian Ocean oscillation

    Indian Academy of Sciences (India)

    It is now well known that there is a strong association of the extremes of the Indian summer monsoon rainfall (ISMR) with the El Niño and southern oscillation (ENSO) and the Equatorial Indian Ocean Oscillation (EQUINOO), later being an east–west oscillation in convection anomaly over the equatorial Indian Ocean. So far ...

  14. Melatonin: functions and ligands.

    Science.gov (United States)

    Singh, Mahaveer; Jadhav, Hemant R

    2014-09-01

    Melatonin is a chronobiotic substance that acts as synchronizer by stabilizing bodily rhythms. Its synthesis occurs in various locations throughout the body, including the pineal gland, skin, lymphocytes and gastrointestinal tract (GIT). Its synthesis and secretion is controlled by light and dark conditions, whereby light decreases and darkness increases its production. Thus, melatonin is also known as the 'hormone of darkness'. Melatonin and analogs that bind to the melatonin receptors are important because of their role in the management of depression, insomnia, epilepsy, Alzheimer's disease (AD), diabetes, obesity, alopecia, migraine, cancer, and immune and cardiac disorders. In this review, we discuss the mechanism of action of melatonin in these disorders, which could aid in the design of novel melatonin receptor ligands. Copyright © 2014 Elsevier Ltd. All rights reserved.

  15. Cross-equatorial flow through an abyssal channel under the complete Coriolis force: Two-dimensional solutions

    Science.gov (United States)

    Stewart, A. L.; Dellar, P. J.

    channel as it crosses the equator. The "non-traditional" contribution to the planetary angular momentum must be balanced by stronger westward flow in the channel, which leads to an increased transport in a northwestward channel, and a reduced transport in a northeastward channel. Our results suggest that as much as 10-30% of the cross-equatorial flow of the AABW may be attributed to the non-traditional components of the Coriolis force.

  16. Stereochemistry of lead(II) complexes with oxygen donor ligands.

    Energy Technology Data Exchange (ETDEWEB)

    Stavilla, Vitalie; Davidovich, Ruven L.; Whitmire, Kenton Herbert (Rice University); Voit, Elena I.; Marinin, Dmitry V.

    2008-10-01

    This review discusses the coordination number (CN) and the coordination geometry of the first coordination sphere of Pb(II) atoms in crystal structures of 98 lead(II) complexes with O-donor ligands and the stereochemically active lone pair of electrons (LP, E) in the terms of the valence shell electron-pair repulsion (VSEPR) model. The CN of Pb(II) atoms of the first coordination sphere has values falling into the range (3 + E) to (6 + E). The following coordination polyhedra-{psi}-tetrahedron (I), {psi}-trigonal bipyramid (II), {psi}-octahedron (III), {psi}-pentagonal bipyramid with an axial (IV) or equatorial (V) vacant position are formed. For the investigated structures of the Pb(II) complexes, the formula of each compound, the overall CN of the Pb(II) atom considered as the sum of the CN in the first coordination sphere and the number of secondary bonds, the polyhedron shape, the Pb-O bond lengths, and O-Pb-O bond angles in the first coordination sphere, secondary bond lengths, references and REFCODEs are presented in the comprehensive Tables. The quantum chemical investigations performed using density functional theory (DFT) method have confirmed the stereochemical activity of the LP of Pb(II) atoms in the studied structures of lead(II) complexes with O-donor ligands.

  17. Response of the equatorial Pacific to chlorophyll pigment in a mixed layer isopycnal ocean general circulation model

    Digital Repository Service at National Institute of Oceanography (India)

    Nakamoto, S.; PrasannaKumar, S.; Oberhuber, J.M.; Ishizaka, J.; Muneyama, K.; Frouin, R.

    pigment concentration from the Coastal Zone Color Scanner (CZCS). In the equatorial Pacific heat accumulation due to a higher abundance of chlorophyll pigments in the equatorial Pacific leads to a decrease of the mixed layer thickness. This generates...

  18. Spread F – an old equatorial aeronomy problem finally resolved?

    Directory of Open Access Journals (Sweden)

    R. F. Woodman

    2009-05-01

    Full Text Available One of the oldest scientific topics in Equatorial Aeronomy is related to Spread-F. It includes all our efforts to understand the physical mechanisms responsible for the existence of ionospheric F-region irregularities, the spread of the traces in a night-time equatorial ionogram – hence its name – and all other manifestations of the same. It was observed for the first time as an abnormal ionogram in Huancayo, about 70 years ago. But only recently are we coming to understand the physical mechanisms responsible for its occurrence and its capricious day to day variability. Several additional techniques have been used to reveal the spatial and temporal characteristics of the F-region irregularities responsible for the phenomenon. Among them we have, in chronological order, radio star scintillations, trans-equatorial radio propagation, satellite scintillations, radar backscatter, satellite and rocket in situ measurements, airglow, total electron content techniques using the propagation of satellite radio signals and, recently, radar imaging techniques. Theoretical efforts are as old as the observations. Nevertheless, 32 years after their discovery, Jicamarca radar observations showed that none of the theories that had been put forward could explain them completely. The observations showed that irregularities were detected at altitudes that were stable according to the mechanisms proposed. A breakthrough came a few years later, again from Jicamarca, by showing that some of the "stable" regions had become unstable by the non-linear propagation of the irregularities from the unstable to the stable region of the ionosphere in the form of bubbles of low density plasma. A problem remained, however; the primary instability mechanism proposed, an extended (generalized Rayleigh-Taylor instability, was too slow to explain the rapid development seen by the observations. Gravity waves in the neutral background have been proposed as a seeding mechanism to

  19. Predatory blue crabs induce stronger nonconsumptive effects in eastern oysters Crassostrea virginica than scavenging blue crabs

    Directory of Open Access Journals (Sweden)

    Avery E. Scherer

    2017-02-01

    Full Text Available By influencing critical prey traits such as foraging or habitat selection, predators can affect entire ecosystems, but the nature of cues that trigger prey reactions to predators are not well understood. Predators may scavenge to supplement their energetic needs and scavenging frequency may vary among individuals within a species due to preferences and prey availability. Yet prey reactions to consumers that are primarily scavengers versus those that are active foragers have not been investigated, even though variation in prey reactions to scavengers or predators might influence cascading nonconsumptive effects in food webs. Oysters Crassostrea virginica react to crab predators by growing stronger shells. We exposed oysters to exudates from crabs fed live oysters or fed aged oyster tissue to simulate scavenging, and to controls without crab cues. Oysters grew stronger shells when exposed to either crab exudate, but their shells were significantly stronger when crabs were fed live oysters. The stronger response to predators than scavengers could be due to inherent differences in diet cues representative of reduced risk in the presence of scavengers or to degradation of conspecific alarm cues in aged treatments, which may mask risk from potential predators subsisting by scavenging.

  20. Stronger Accent Following a Stroke: The Case of a Trilingual with Aphasia

    Science.gov (United States)

    Levy, Erika S.; Goral, Mira; De Diesbach, Catharine Castelluccio; Law, Franzo, II

    2011-01-01

    This study documents patterns of change in speech production in a multilingual with aphasia following a cerebrovascular accident (CVA). EC, a right-handed Hebrew-English-French trilingual man, had a left fronto-temporo-parietal CVA, after which he reported that his (native) Hebrew accent became stronger in his (second language) English. Recordings…

  1. Peptide-MHC class I stability is a stronger predictor of CTL immunogenicity than peptide affinity

    DEFF Research Database (Denmark)

    Harndahl, Mikkel Nors; Rasmussen, Michael; Nielsen, Morten

    2012-01-01

    Peptide-MHC class I stability is a stronger predictor of CTL immunogenicity than peptide affinity Mikkel Harndahla, Michael Rasmussena, Morten Nielsenb, Soren Buusa,∗ a Laboratory of Experimental Immunology, Faculty of Health Sciences, University of Copenhagen, Denmark b Center for Biological Seq...... al., 2007. J. Immunol. 178, 7890–7901. doi:10.1016/j.molimm.2012.02.025...

  2. First-order dominance: stronger characterization and a bivariate checking algorithm

    DEFF Research Database (Denmark)

    Range, Troels Martin; Østerdal, Lars Peter Raahave

    2018-01-01

    distributions. Utilizing that this problem can be formulated as a transportation problem with a special structure, we provide a stronger characterization of multivariate first-order dominance and develop a linear time complexity checking algorithm for the bivariate case. We illustrate the use of the checking...

  3. Fasting insulin is a stronger cardiovascular risk factor in women than in men

    NARCIS (Netherlands)

    Oterdoom, Leendert H.; de Vries, Aiko P. J.; Gansevoort, Ron T.; de Jong, Paul E.; Gans, Reinold O. B.; Bakker, Stephan J. L.

    Diabetes is a stronger risk factor for cardiovascular disease (CVD) in women than in men. It is not known whether there is also a sex difference in the association between hyperinsulinaemia, reflecting insulin resistance, and CVD. Fasting insulin was assessed with a specific assay in 6916 fasting,

  4. A stronger patch test elicitation reaction to the allergen hydroxycitronellal plus the irritant sodium lauryl sulfate

    DEFF Research Database (Denmark)

    Heydorn, S; Andersen, Klaus Ejner; Johansen, Jeanne Duus

    2003-01-01

    Household and cleaning products often contain both allergens and irritants. The aim of this double-blinded, randomized, paired study was to determine whether patch testing with an allergen (hydroxycitronellal) combined with an irritant [sodium lauryl sulfate (SLS)] cause a stronger patch test...

  5. A Human Capital Framework for a Stronger Teacher Workforce. Advancing Teaching--Improving Learning. White Paper

    Science.gov (United States)

    Myung, Jeannie; Martinez, Krissia; Nordstrum, Lee

    2013-01-01

    Building a stronger teacher workforce requires the thoughtful orchestration of multiple processes working together in a human capital system. This white paper presents a framework that can be used to take stock of current efforts to enhance the teacher workforce in school districts or educational organizations, as well as their underlying theories…

  6. Harmful drinking after job loss: a stronger association during the post-2008 economic crisis?

    NARCIS (Netherlands)

    de Goeij, Moniek C. M.; Bruggink, Jan-Willem; Otten, Ferdy; Kunst, Anton E.

    2017-01-01

    This study investigated, among the Dutch working population, whether job loss during the post-2008 economic crisis is associated with harmful drinking and whether this association is stronger than before the crisis. Repeated cross-sectional data from the Dutch Health Interview Survey 2004-2013 were

  7. Role of interannual Kelvin wave propagations in the equatorial Atlantic on the Angola Benguela Current system

    Science.gov (United States)

    Imbol Koungue, Rodrigue Anicet; Illig, Serena; Rouault, Mathieu

    2017-06-01

    The link between equatorial Atlantic Ocean variability and the coastal region of Angola-Namibia is investigated at interannual time scales from 1998 to 2012. An index of equatorial Kelvin wave activity is defined based on Prediction and Research Moored Array in the Tropical Atlantic (PIRATA). Along the equator, results show a significant correlation between interannual PIRATA monthly dynamic height anomalies, altimetric monthly Sea Surface Height Anomalies (SSHA), and SSHA calculated with an Ocean Linear Model. This allows us to interpret PIRATA records in terms of equatorial Kelvin waves. Estimated phase speed of eastward propagations from PIRATA equatorial mooring remains in agreement with the linear theory, emphasizing the dominance of the second baroclinic mode. Systematic analysis of all strong interannual equatorial SSHA shows that they precede by 1-2 months extreme interannual Sea Surface Temperature Anomalies along the African coast, which confirms the hypothesis that major warm and cold events in the Angola-Benguela current system are remotely forced by ocean atmosphere interactions in the equatorial Atlantic. Equatorial wave dynamics is at the origin of their developments. Wind anomalies in the Western Equatorial Atlantic force equatorial downwelling and upwelling Kelvin waves that propagate eastward along the equator and then poleward along the African coast triggering extreme warm and cold events, respectively. A proxy index based on linear ocean dynamics appears to be significantly more correlated with coastal variability than an index based on wind variability. Results show a seasonal phasing, with significantly higher correlations between our equatorial index and coastal SSTA in October-April season.

  8. Can absolute and proportional anthropometric characteristics distinguish stronger and weaker powerlifters?

    Science.gov (United States)

    Keogh, Justin W L; Hume, Patria A; Pearson, Simon N; Mellow, Peter J

    2009-11-01

    This study sought to compare the anthropometric profiles of 17 weaker and 17 stronger Australasian and Pacific powerlifters who had competed in a regional-, national-, or international-level powerlifting competition in New Zealand. Stronger lifters were defined as those having a Wilks score greater than 410, whereas those in the weaker group had a Wilks score less than 370. Each powerlifter was assessed for 37 anthropometric dimensions by International Society for the Advancement of Kinanthropometry (ISAK) level II and III accredited anthropometrists. Because all powerlifters were highly mesomorphic and possessed large girths and bone breadths, both in absolute terms and when expressed as Phantom-Z scores compared through the Phantom, relatively few significant anthropometric differences were observed. However, stronger lifters had significantly greater muscle mass and larger muscular girths in absolute terms as well as greater Brugsch Index (chest girth/height) and "Phantom"-normalized muscle mass, upper arm, chest, and forearm girths. In terms of the segment lengths and bone breadths, the only significant difference was that stronger lifters had a significantly shorter lower leg than weaker lifters. Because the majority of the significant differences were for muscle mass and muscular girths, it would appear likely that these differences contributed to the stronger lifters' superior performance. Powerlifters may therefore need to devote some of their training to the development of greater levels of muscular hypertrophy if they wish to continue to improve their performance. To better understand the anthropometric determinants of muscular strength, future research should recruit larger samples (particularly of elite lifters) and follow these subjects prospectively.

  9. Exploring the Hydrolytic Behavior of the Platinum(IV) Complexes with Axial Acetato Ligands.

    Science.gov (United States)

    Zhao, Jian; Xu, Zichen; Lin, Jing; Gou, Shaohua

    2017-08-21

    Platinum(IV) complexes are generally thought to be kinetically inert, and are expected to be stable enough to resist premature aquation before entering the cancer cells. Nevertheless, in this work, complex 2 with axial acetato ligands can hydrolyze relatively quickly under biologically relevant conditions with a half-life of 91.7 min, resulting in the loss of the equatorial chlorido ligand. Further study indicated that the fast hydrolysis of complex 2 may be attributed to the strong σ-donor ability of N-isopropyl-1R,2R-diaminocyclohexane, and an increasing σ-donor ability of the amine group can promote the hydrolysis rate of the corresponding platinum(IV) complex. The experiment results were proven by the corresponding DFT calculation. Our study can help to re-evaluate the aqueous properties of the platinum(IV) complexes with axial acetate, which may be less inert to hydrolysis than expected under biologically relevant conditions.

  10. Pelagic microplastics around an archipelago of the Equatorial Atlantic.

    Science.gov (United States)

    Ivar do Sul, Juliana A; Costa, Monica F; Barletta, Mário; Cysneiros, Francisco José A

    2013-10-15

    Plastic marine debris is presently widely recognised as an important environmental pollutant. Such debris is reported in every habitat of the oceans, from urban tourist beaches to remote islands and from the ocean surface to submarine canyons, and is found buried and deposited on sandy and cobble beaches. Plastic marine debris varies from micrometres to several metres in length and is potentially ingested by animals of every level of the marine food web. Here, we show that synthetic polymers are present in subsurface plankton samples around Saint Peter and Saint Paul Archipelago in the Equatorial Atlantic Ocean. To explain the distribution of microplastics around the Archipelago, we proposed a generalised linear model (GLM) that suggests the existence of an outward gradient of mean plastic-particle densities. Plastic items can be autochthonous or transported over large oceanic distances. One probable source is the small but persistent fishing fleet using the area. Copyright © 2013 Elsevier Ltd. All rights reserved.

  11. Combined radar observations of equatorial electrojet irregularities at Jicamarca

    Directory of Open Access Journals (Sweden)

    D. L. Hysell

    2007-03-01

    Full Text Available Daytime equatorial electrojet plasma irregularities were investigated using five distinct radar diagnostics at Jicamarca including range-time-intensity (RTI mapping, Faraday rotation, radar imaging, oblique scattering, and multiple-frequency scattering using the new AMISR prototype UHF radar. Data suggest the existence of plasma density striations separated by 3–5 km and propagating slowly downward. The striations may be caused by neutral atmospheric turbulence, and a possible scenario for their formation is discussed. The Doppler shifts of type 1 echoes observed at VHF and UHF frequencies are compared and interpreted in light of a model of Farley Buneman waves based on kinetic ions and fluid electrons with thermal effects included. Finally, the up-down and east-west asymmetries evident in the radar observations are described and quantified.

  12. Analytical solutions for J 2-perturbed unbounded equatorial orbits

    Science.gov (United States)

    Martinusi, Vladimir; Gurfil, Pini

    2013-01-01

    While solutions for bounded orbits about oblate spheroidal planets have been presented before, similar solutions for unbounded motion are scarce. This paper develops solutions for unbounded motion in the equatorial plane of an oblate spheroidal planet, while taking into account only the J 2 harmonic in the gravitational potential. Two cases are distinguished: A pseudo-parabolic motion, obtained for zero total specific energy, and a pseudo-hyperbolic motion, characterized by positive total specific energy. The solutions to the equations of motion are expressed using elliptic integrals. The pseudo-parabolic motion unveils a new orbit, termed herein the fish orbit, which has not been observed thus far in the perturbed two-body problem. The pseudo-hyperbolic solutions show that significant differences exist between the Keplerian flyby and the flyby performed under the the J 2 zonal harmonic. Numerical simulations are used to quantify these differences.

  13. Multistation digisonde observations of equatorial spread F in South America

    Directory of Open Access Journals (Sweden)

    B. W. Reinisch

    2004-09-01

    Full Text Available Directional ionogram and F-region drift observations were conducted at seven digisonde stations in South America during the COPEX campaign from October to December 2002. Five stations in Brazil, one in Argentina, and one in Peru, monitored the ionosphere across the continent to study the onset and development of F-region density depletions that cause equatorial spread F (ESF. New ionosonde techniques quantitatively describe the prereversal uplifting of the F layer at the magnetic equator and the eastward motion of the depletions over the stations. Three of the Brazilian stations were located along a field line with a 350-km apex over the equator to investigate the relation of the occurrence of ESF and the presence of sporadic E-layers at the two E-region intersections of the field line. No simple correlation was found.

  14. Priority areas for large mammal conservation in Equatorial Guinea.

    Science.gov (United States)

    Murai, Mizuki; Ruffler, Heidi; Berlemont, Antoine; Campbell, Genevieve; Esono, Fidel; Agbor, Anthony; Mbomio, Domingo; Ebana, Agustín; Nze, Antonio; Kühl, Hjalmar S

    2013-01-01

    Hunting is one of the main driving forces behind large mammal density distribution in many regions of the world. In tropical Africa, urban demand for bushmeat has been shown to dominate over subsistence hunting and its impact often overrides spatial-ecological species characteristics. To effectively protect remaining mammal populations the main factors that influence their distribution need to be integrated into conservation area prioritisation and management plans. This information has been lacking for Río Muni, Equatorial Guinea, as prior studies have been outdated or have not systematically covered the continental region of the country. In this study we evaluated: 1) the relative importance of local vs. commercial hunting; 2) wildlife density of protected vs. non-protected areas; and 3) the importance of ecological factors vs. human influence in driving mammal density distribution in Río Muni. We adopted a systematic countrywide line transect approach with particular focus on apes and elephants, but also including other mammal species. For analysis of field data we used generalised linear models with a set of predictor variables representing ecological conditions, anthropogenic pressure and protected areas. We estimate that there are currently 884 (437-1,789) elephants and 11,097 (8,719-13,592) chimpanzees and gorillas remaining in Río Muni. The results indicate strong hunting pressures on both local and commercial levels, with roads demonstrating a negative impact on elephants and overall mammal body mass. Protected areas played no role in determining any of the mammal species distributions and significant human hunting signs were found inside these protected areas, illustrating the lack of environmental law enforcement throughout the country. Río Muni is currently under-represented in conservation efforts in Western Equatorial Africa, and we recommend a focus on cross-boundary conservation, in particular in the Monte Alén-Monts de Cristal and Río Campo

  15. Prevalence of refractive errors in children in Equatorial Guinea.

    Science.gov (United States)

    Soler, Margarita; Anera, Rosario G; Castro, José J; Jiménez, Raimundo; Jiménez, José R

    2015-01-01

    The aim of this work is to evaluate the epidemiological aspects of the refractive errors in school-aged children in Malabo (Island of Bioko), Equatorial Guinea (western-central Africa). A total of 425 schoolchildren (209 male subjects and 216 female subjects, aged between 6 and 16 years) were examined to evaluate their refraction errors in Malabo, Equatorial Guinea (western-central Africa). The examination included autorefraction with cycloplegia, measurement of visual acuity (VA) for far vision, and the curvature radii of the main meridians of the anterior surface of the cornea. A low prevalence of myopia was found (≤-0.50 diopters [D] spherical equivalent), with unilateral and bilateral myopia being 10.4 and 5.2%, respectively. The prevalence of unilateral and bilateral hypermetropia (≥2.0 D spherical equivalent) was 3.1 and 1.6%, respectively. Astigmatism (≤-0.75 D) was found in unilateral form in 32.5% of these children, whereas bilateral astigmatism was found in 11.8%. After excluding children having any ocular pathology, the low prevalence of high refractive errors signified good VA in these children. Significant differences were found in the distribution of the refractive errors by age and type of schooling (public or private) but not by sex. In general, the radii of the anterior of the cornea did not vary significantly with age. The mean refractive errors found were low and therefore VA was high in these children. There was a low prevalence of myopia, with significantly higher values in those who attended private schools (educationally and socioeconomically more demanding). Astigmatism was the most frequent refractive error.

  16. A Generalized Equatorial Model for the Accelerating Solar Wind

    Science.gov (United States)

    Tasnim, S.; Cairns, Iver H.; Wheatland, M. S.

    2018-02-01

    A new theoretical model for the solar wind is developed that includes the wind's acceleration, conservation of angular momentum, deviations from corotation, and nonradial velocity and magnetic field components from an inner boundary (corresponding to the onset of the solar wind) to beyond 1 AU. The model uses a solution of the time-steady isothermal equation of motion to describe the acceleration and analytically predicts the Alfvénic critical radius. We fit the model to near-Earth observations of the Wind spacecraft during the solar rotation period of 1-27 August 2010. The resulting data-driven model demonstrates the existence of noncorotating, nonradial flows and fields from the inner boundary (r = rs) outward and predicts the magnetic field B = (Br,Bϕ), velocity v = (vr,vϕ), and density n(r,ϕ,t), which vary with heliocentric distance r, heliolatitude ϕ, and time t in a Sun-centered standard inertial plane. The description applies formally only in the equatorial plane. In a frame corotating with the Sun, the transformed velocity v' and a field B' are not parallel, resulting in an electric field with a component Ez' along the z axis. The resulting E'×B'=E'×B drift lies in the equatorial plane, while the ∇B and curvature drifts are out of the plane. Together these may lead to enhanced scattering/heating of sufficiently energetic particles. The model predicts that deviations δvϕ from corotation at the inner boundary are common, with δvϕ(rs,ϕs,ts) comparable to the transverse velocities due to granulation and supergranulation motions. Abrupt changes in δvϕ(rs,ϕs,ts) are interpreted in terms of converging and diverging flows at the cell boundaries and centers, respectively. Large-scale variations in the predicted angular momentum demonstrate that the solar wind can drive vorticity and turbulence from near the Sun to 1 AU and beyond.

  17. A tropospheric ozone maximum over the equatorial Southern Indian Ocean

    Directory of Open Access Journals (Sweden)

    L. Zhang

    2012-05-01

    Full Text Available We examine the distribution of tropical tropospheric ozone (O3 from the Microwave Limb Sounder (MLS and the Tropospheric Emission Spectrometer (TES by using a global three-dimensional model of tropospheric chemistry (GEOS-Chem. MLS and TES observations of tropospheric O3 during 2005 to 2009 reveal a distinct, persistent O3 maximum, both in mixing ratio and tropospheric column, in May over the Equatorial Southern Indian Ocean (ESIO. The maximum is most pronounced in 2006 and 2008 and less evident in the other three years. This feature is also consistent with the total column O3 observations from the Ozone Mapping Instrument (OMI and the Atmospheric Infrared Sounder (AIRS. Model results reproduce the observed May O3 maximum and the associated interannual variability. The origin of the maximum reflects a complex interplay of chemical and dynamic factors. The O3 maximum is dominated by the O3 production driven by lightning nitrogen oxides (NOx emissions, which accounts for 62% of the tropospheric column O3 in May 2006. We find the contribution from biomass burning, soil, anthropogenic and biogenic sources to the O3 maximum are rather small. The O3 productions in the lightning outflow from Central Africa and South America both peak in May and are directly responsible for the O3 maximum over the western ESIO. The lightning outflow from Equatorial Asia dominates over the eastern ESIO. The interannual variability of the O3 maximum is driven largely by the anomalous anti-cyclones over the southern Indian Ocean in May 2006 and 2008. The lightning outflow from Central Africa and South America is effectively entrained by the anti-cyclones followed by northward transport to the ESIO.

  18. CCR2 elimination in mice results in larger and stronger tibial bones but bone loss is not attenuated following ovariectomy or muscle denervation.

    Science.gov (United States)

    Mader, Tara L; Novotny, Susan A; Lin, Angela S; Guldberg, Robert E; Lowe, Dawn A; Warren, Gordon L

    2014-11-01

    Bone loss due to age and disuse contributes to osteoporosis and increases fracture risk. It has been hypothesized that such bone loss can be attenuated by modulation of the C-C chemokine receptor 2 (CCR2) and/or its ligands. The objectives of this study were to examine the effects of genetic elimination of CCR2 on cortical and trabecular bones in the mouse tibia and how bone loss was impacted following disuse and estrogen loss. Female CCR2 knockout (CCR2(-/-)) and wildtype mice underwent ovariectomy (OVX) or denervation of musculature adjacent to the tibia (DEN) to induce bone loss. Cortical and trabecular structural properties as well as mechanical properties (i.e., strength) of tibial bones were measured. Compared to wildtype mice, CCR2(-/-) mice had tibiae that were up to 9% larger and stronger; these differences could be explained mainly by the 17% greater body mass (P bone loss per se. These findings indicate that while CCR2(-/-) mice do have larger and stronger bones than do wildtype mice, there is minimal evidence that CCR2 elimination provides protection against bone loss during disuse and estrogen loss.

  19. Glutamate receptor ligands

    DEFF Research Database (Denmark)

    Guldbrandt, Mette; Johansen, Tommy N; Frydenvang, Karla Andrea

    2002-01-01

    Homologation and substitution on the carbon backbone of (S)-glutamic acid [(S)-Glu, 1], as well as absolute stereochemistry, are structural parameters of key importance for the pharmacological profile of (S)-Glu receptor ligands. We describe a series of methyl-substituted 2-aminoadipic acid (AA...... or slightly lower potencies than (S)-AA [e.g., EC(50) = 76 microM for (2S,4S)-4-methyl-AA (5a) as compared to EC(50) = 35 microM for (S)-AA]. The position of the methyl substituent had a profound effect on the observed pharmacology, whereas the absolute stereochemistry at the methylated carbon atom had a very......) analogs, and the synthesis, stereochemistry, and enantiopharmacology of 3-methyl-AA (4a-d), 4-methyl-AA (5a-d), 5-methyl-AA (6a-d), and (E)-Delta(4)-5-methyl-AA (7a and 7b) are reported. The compounds were resolved using chiral HPLC and the configurational assignments of the enantiomers were based on X...

  20. CONVECTIVE BURSTS AND THE COUPLING OF SATURN'S EQUATORIAL STORMS AND INTERIOR ROTATION

    International Nuclear Information System (INIS)

    Heimpel, Moritz; Aurnou, Jonathan M.

    2012-01-01

    Temporal variations of Saturn's equatorial jet and magnetic field hint at rich dynamics coupling the atmosphere and the deep interior. However, it has been assumed that rotation of the interior dynamo must be steady over tens of years of modern observations. Here we use a numerical convection model and scaling estimates to show how equatorial convective bursts can transfer angular momentum to the deeper interior. The numerical model allows angular momentum transfer between a fluid outer spherical shell and a rigid inner sphere. Convection drives a prograde equatorial jet exhibiting quasiperiodic bursts that fill the equatorial volume outside the tangent cylinder. For each burst strong changes in the equatorial surface velocity are associated with retrograde torque on the inner sphere. Our results suggest that Saturn's Great White Spot, a giant storm that was observed to fill the equatorial region in 1990, could mobilize a volume of fluid carrying roughly 15% of Saturn's moment of inertia. Conservation of angular momentum then implies that a 20% change in the equatorial jet angular velocity could change the average interior rotation rate by about 0.1%—roughly an order of magnitude less than the apparent rotation rate changes associated with Saturn's kilometric radio (SKR) signal. However, if the SKR signal originates outside the liquid metal core in a 'planetary tachocline' that separates the layer of fast zonal flow from the magnetically controlled and slowly convecting deep interior, then convective bursts can provide a possible mechanism for the observed ∼1% SKR changes.

  1. The streaming-trapped ion interface in the equatorial inner magnetosphere

    Science.gov (United States)

    Lin, J.; Horwitz, J. L.; Gallagher, D.; Pollock, C. J.

    1994-01-01

    Spacecraft measurements of core ions on L=4-7 field-lines typically show trapped ion distributions near the magnetic equator, and frequently indicate field-aligned ion streams at higher latitudes. The nature of the transition between them may indicate both the microphysics of hot-cold plasma interactions and overall consequences for core plasma evolution. We have undertaken a statistical analysis and characterization of this interface and its relation to the equatorial region of the inner magnetosphere. In this analysis, we have characterized such features as the equatorial ion flux anisotropy, the penetration of field-aligned ionospheric streams into the equatorial region, the scale of the transition into trapped ion populations, and the transition latitude. We found that most transition latitudes occur within 13 deg of the equator. The typical values of equatorial ion anisotropies are consistent with bi-Maxwellian temperature ratios of T(sub perpendicular)/T(sub parallel) in the range of 3-5. The latitudinal scales for the edges of the trapped ion populations display a rather strong peak in the 2-3 deg range. We also found that there is a trend for the penetration ratio, the anisotropy half width, and the transition scale length to decrease with a higher equatorial ion anisotropy. We may interpret these features in terms of Liouville mapping of equatorially trapped ions and the reflection of the incoming ionospheric ion streams from the equatorial potential peaks associated with such trapped ions.

  2. A multi-model approach to the Atlantic Equatorial mode: impact on the West African monsoon

    Energy Technology Data Exchange (ETDEWEB)

    Losada, T.; Rodriguez-Fonseca, B. [Universidad Complutense de Madrid, Madrid (Spain); Janicot, S.; Gervois, S. [LOCEAN/IPSL, CNRS, Universite Pierre et Marie Curie, Paris (France); Chauvin, F. [GAME/CNRM, Meteo-France/CNRS, Toulouse (France); Ruti, P. [Progetto Speciale Clima Globale, Ente Nazionale per le NuoveTecnologie, Rome (Italy)

    2010-07-15

    This paper is focused on the West African anomalous precipitation response to an Atlantic Equatorial mode whose origin, development and damping resembles the observed one during the last decades of the XXth century. In the framework of the AMMA-EU project, this paper analyses the atmospheric response to the Equatorial mode using a multimodel approach with an ensemble of integrations from 4 AGCMs under a time varying Equatorial SST mode. The Guinean Gulf precipitation, which together with the Sahelian mode accounts for most of the summer West African rainfall variability, is highly coupled to this Equatorial Atlantic SST mode or Atlantic Nino. In a previous study, done with the same models under 1958-1997 observed prescribed SSTs, most of the models identify the Equatorial Atlantic SST mode as the one most related to the Guinean Gulf precipitation. The models response to the positive phase of equatorial Atlantic mode (warm SSTs) depicts a direct impact in the equatorial Atlantic, leading to a decrease of the local surface temperature gradient, weakening the West African Monsoon flow and the surface convergence over the Sahel. (orig.)

  3. Crosstalk in concurrent repeated games impedes direct reciprocity and requires stronger levels of forgiveness.

    Science.gov (United States)

    Reiter, Johannes G; Hilbe, Christian; Rand, David G; Chatterjee, Krishnendu; Nowak, Martin A

    2018-02-07

    Direct reciprocity is a mechanism for cooperation among humans. Many of our daily interactions are repeated. We interact repeatedly with our family, friends, colleagues, members of the local and even global community. In the theory of repeated games, it is a tacit assumption that the various games that a person plays simultaneously have no effect on each other. Here we introduce a general framework that allows us to analyze "crosstalk" between a player's concurrent games. In the presence of crosstalk, the action a person experiences in one game can alter the person's decision in another. We find that crosstalk impedes the maintenance of cooperation and requires stronger levels of forgiveness. The magnitude of the effect depends on the population structure. In more densely connected social groups, crosstalk has a stronger effect. A harsh retaliator, such as Tit-for-Tat, is unable to counteract crosstalk. The crosstalk framework provides a unified interpretation of direct and upstream reciprocity in the context of repeated games.

  4. A stronger patch test elicitation reaction to the allergen hydroxycitronellal plus the irritant sodium lauryl sulfate

    DEFF Research Database (Denmark)

    Heydorn, S; Andersen, K E; Johansen, J D

    2003-01-01

    elicitation reaction than patch testing with the allergen (hydroxycitronellal) alone, in patients previously patch tested positive to hydroxycitronellal. A stronger patch test elicitation reaction was defined as at least 1 day of patch test reading showing more positive patch tests......Household and cleaning products often contain both allergens and irritants. The aim of this double-blinded, randomized, paired study was to determine whether patch testing with an allergen (hydroxycitronellal) combined with an irritant [sodium lauryl sulfate (SLS)] cause a stronger patch test...... (+, ++ or +++) on the forearm patch tested with 6 concentrations of SLS plus hydroxycitronellal than on the forearm tested with 6 concentrations of hydroxycitronellal alone and no day of patch test readings showing more positive tests on the hydroxycitronellal forearm. 15/20 (75%) had at least 1 day of patch test reading...

  5. Daytime warming has stronger negative effects on soil nematodes than night-time warming

    OpenAIRE

    Yan, Xiumin; Wang, Kehong; Song, Lihong; Wang, Xuefeng; Wu, Donghui

    2017-01-01

    Warming of the climate system is unequivocal, that is, stronger warming during night-time than during daytime. Here we focus on how soil nematodes respond to the current asymmetric warming. A field infrared heating experiment was performed in the western of the Songnen Plain, Northeast China. Three warming modes, i.e. daytime warming, night-time warming and diurnal warming, were taken to perform the asymmetric warming condition. Our results showed that the daytime and diurnal warming treatmen...

  6. World Bank: Management Controls Stronger, But Challenges in Fighting Corruption Remain

    Science.gov (United States)

    2000-04-01

    outline for possible World Development Report on institutions, including corruption . Completed • Prepare Europe and Central Asia Region...Management Controls Stronger, but Challenges in Fighting Corruption Remain If , 20000417 062 G A O Accountability * Integrity * Reliability GAO... corruption —broadly defined as the abuse of public office for private gain— ’The "World Bank" and "Bank" refer to the World Bank Group of institutions

  7. A stronger version of matrix convexity as applied to functions of Hermitian matrices

    Directory of Open Access Journals (Sweden)

    Kagan Abram

    1999-01-01

    Full Text Available A stronger version of matrix convexity, called hyperconvexity is introduced. It is shown that the function is hyperconvex on the set of Hermitian matrices and is hyperconvex on the set of positive definite Hermitian matrices. The new concept makes it possible to consider weighted averages of matrices of different orders. Proofs use properties of the Fisher information matrix, a fundamental concept of mathematical statistics.

  8. Decisive Thaw: The Changing Pattern of Relations between Nigeria and Equatorial Guinea, 1980-2005

    Directory of Open Access Journals (Sweden)

    David Aworawo

    2010-04-01

    Full Text Available This article examines the nature and changing pattern of relations between Nigeria and Equatorial Guinea from 1980-2005. It states that relations between the countries improved tremendously in the quarter century covered in this study compared to the two decades preceding that time frame (1960-1980 due to of a number of domesticpolitical and economic changes that occurred in both countries, as well as the transformation of the international system in the late 1980s and early 1990s. The paper explores the specific changes that took place in Nigerian-Equatorial Guinean relations from1980 onwards and the factors that influenced them. The termination of the brutal and violent rule of President Macias Nguema in Equatorial Guinea opened the way for improved relations between Nigeria and Equatorial Guinea. The shift from dependence on cocoa to petroleum exports in Equatorial Guinea also helped to promote cordial relations since the ill-treatment of Nigerian workers in Equatorial Guinea’s cocoa plantations had been a thorny issue in Nigerian-Equatorial Guinean relations in previous decades. The end of the Cold War and apartheid between 1989 and 1994 were also important factors that shaped relations. All these were issues that had previously negatively affected cordial relations between the countries. Thisarticle therefore discusses relations between Nigeria and Equatorial Guinea within the context of the post-Cold War international system and intra-African relations. It also argues that although improvements were recorded in Nigerian-Equatorial Guinean relations between 1980 and 2005, there remain numerous avenues that could be explored for yet better relations.

  9. The physical and theoretical basis of solar-terrestrial relationships 1. Equatorial locations

    International Nuclear Information System (INIS)

    Njau, E.C.

    1988-07-01

    The theory of solar-terrestrial relationships developed earlier by the author is extended to incorporate expressions that represent the non-linear responses of the earth-atmosphere system to incoming solar radiation in a more detailed manner. Application of the extended theory to equatorial locations leads to new and interesting features that are consistent with past observations. It also predicts the existence of new oscillations in the equatorial atmosphere whose causative physical processes are given and explained. Non-equatorial locations are treated along similar lines in Part 2 of the series. (author). 44 refs

  10. A space system integrating earth observation and mobile communications for equatorial remote areas

    Science.gov (United States)

    Ceballos, Decio C.

    1993-10-01

    The integration of two constellations of light and low-cost satellites, the Equatorial Communications (ECO) system and a polar orbit system for World Observation and Monitoring (WOM), is proposed. The WOM involves eight satellites and portable data reception and processing equipment. Onboard data compression enables UHF transmission of earth observation data. A system for global coverage with a temporal result of two passes per day is proposed. The ECO involves eight satellites in an equatorial constellation at 2000 mm. This system can supply low-orbit communications for equatorial countries and assist in the daily monitoring of ecologically protected areas.

  11. Ligand-guided receptor optimization.

    Science.gov (United States)

    Katritch, Vsevolod; Rueda, Manuel; Abagyan, Ruben

    2012-01-01

    Receptor models generated by homology or even obtained by crystallography often have their binding pockets suboptimal for ligand docking and virtual screening applications due to insufficient accuracy or induced fit bias. Knowledge of previously discovered receptor ligands provides key information that can be used for improving docking and screening performance of the receptor. Here, we present a comprehensive ligand-guided receptor optimization (LiBERO) algorithm that exploits ligand information for selecting the best performing protein models from an ensemble. The energetically feasible protein conformers are generated through normal mode analysis and Monte Carlo conformational sampling. The algorithm allows iteration of the conformer generation and selection steps until convergence of a specially developed fitness function which quantifies the conformer's ability to select known ligands from decoys in a small-scale virtual screening test. Because of the requirement for a large number of computationally intensive docking calculations, the automated algorithm has been implemented to use Linux clusters allowing easy parallel scaling. Here, we will discuss the setup of LiBERO calculations, selection of parameters, and a range of possible uses of the algorithm which has already proven itself in several practical applications to binding pocket optimization and prospective virtual ligand screening.

  12. Geochemical characterization of organic ligands for copper(II) in different molecular size fractions in Lake Biwa, Japan

    Energy Technology Data Exchange (ETDEWEB)

    Fengchang Wu [Chinese Academy of Science, Guiyang (China). Inst. of Geochemistry; Eiichiro Tanoue [Nagoya University, Nagoya (Japan). Graduate School of Environmental Studies

    2001-07-01

    In a previous study, we reported the isolation of organic ligands for copper(II), their mass distribution and fluorescence properties in different molecular size fractions of the waters in Lake Biwa by immobilized metal ion affinity chromatography (IMAC) and three dimensional excitation/emission matrix spectroscopy (3DEEM) (Wu, F., Tanoue, E., 2001. Molecular mass distributions and fluorescence characteristics of organic ligands for copper (II) in Lake Biwa, Japan. Org. Geochem. 32, 11-20). In this continuous study, geochemical properties of these isolated ligand fractions were characterized in terms of binding complexation, functional groups and amino acid composition. The results show that two ligand classes (L{sub 1} and L{sub 2}) were recovered from all molecular size ligand fractions, L{sub 1} with a conditional stability constant (LogK'{sub CuL}) of 7.82-9.56, and L{sub 2} with a LogK'{sub CuL} value of 7.05-8.78. The stronger ligands with protein-like fluorescence were of recent biogenic origin, and the weaker ligands with humic-like fluorescence were related to refractory humic substances. Functional groups responsible for the fluorescence in the ligand fractions are also discussed. The results presented here would have significance for understanding the nature of natural organic ligands and their biogeochemical role in aquatic systems. (author)

  13. An Analysis of Unseasonal Equatorial Plasma Bubbles in July 2014

    Science.gov (United States)

    Carter, B. A.; Currie, J. L.; Pradipta, R.; Groves, K. M.; Caton, R. G.; Yokoyama, T.

    2017-12-01

    In the equatorial ionosphere, the Raleigh-Taylor (RT) plasma instability in the post sunset region is known to cause plasma depletions, known as equatorial plasma bubbles (EPBs). These EPBs can have adverse effects on satellite-reliant technologies by causing scintillations in the phase and amplitude of Global Navigation Satellite System (GNSS) signals. The effect of EPBs on satellite-reliant technologies highlights a need for reliable forecasting of EPBs in the low-latitude regions, which requires a solid understanding of their climatology and daily variability. The climatology of EPB occurrence is known to correlate with the angle between the magnetic field and solar terminator. This angle controls the longitudinal E-region conductivity gradient across the day-night terminator, which influences the strength of the pre-reversal enhancement in the upward plasma drift, a dominant term in the linear RT growth rate. This relationship is well established from ground-based GNSS and satellite-based studies. However, reliable forecasts have not been developed by space weather forecasting agencies due to the lack of understanding of EPB daily variability. During July, EPB occurrence is small in the South-East Asia longitude sector due to the relatively large angle between the magnetic field and solar terminator. As a result, the pre-reversal enhancement in the upward plasma drift is typically low during this period, creating less favourable conditions for EPB growth. However, despite the typically low pre-reversal enhancement strength, this analysis reveals that July 2014 is not devoid of EPB events above South-East Asia. These unseasonal EPB events during July 2014 are studied in the context of the prevalently low solar and geomagnetic activity conditions. Given the lack of solar and geomagnetic control, the influence of the lower atmosphere on EPB generation (e.g., via atmospheric gravity wave seeding) is explored. These events provide a unique opportunity to investigate

  14. Characteristics of Extreme Summer Convection over equatorial America and Africa

    Science.gov (United States)

    Zuluaga, M. D.; Houze, R.

    2013-12-01

    Fourteen years of Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar (PR) version 7 data for June-August show the temporal and spatial characteristics of extreme convection over equatorial regions of the American and African continents. We identify three types of extreme systems: storms with deep convective cores (contiguous convective 40 dBZ echoes extending ≥10 km in height), storms with wide convective cores (contiguous convective 40 dBZ echoes with areas >1,000 km2) and storms with broad stratiform regions (stratiform echo >50,000 km2). European Centre for Medium-Range Weather Forecast (ECMWF) reanalysis is used to describe the environmental conditions around these forms of extreme convection. Storms with deep convective cores occur mainly over land: in the equatorial Americas, maximum occurrence is in western Mexico, Northern Colombia and Venezuela; in Africa, the region of maximum occurrence is a broad zone enclosing the central and west Sudanian Savanna, south of the Sahel region. Storms with wide convective radar echoes occur in these same general locations. In the American sector, storms with broad stratiform precipitation regions (typifying robust mesoscale convective systems) occur mainly over the eastern tropical Pacific Ocean and the Colombia-Panama bight. In the African sector, storms with broad stratiform precipitation areas occur primarily over the eastern tropical Atlantic Ocean near the coast of West Africa. ECMWF reanalyses show how the regions of extreme deep convection associated with both continents are located mainly in regions affected by diurnal heating and influenced by atmospheric jets in regions with strong humidity gradients. Composite analysis of the synoptic conditions leading to the three forms of extreme convection provides insights into the forcing mechanisms in which these systems occur. These analyses show how the monsoonal flow directed towards the Andes slopes is mainly what concentrates the occurrence of extreme

  15. Snowball Earth termination by destabilization of equatorial permafrost methane clathrate.

    Science.gov (United States)

    Kennedy, Martin; Mrofka, David; von der Borch, Chris

    2008-05-29

    The start of the Ediacaran period is defined by one of the most severe climate change events recorded in Earth history--the recovery from the Marinoan 'snowball' ice age, approximately 635 Myr ago (ref. 1). Marinoan glacial-marine deposits occur at equatorial palaeolatitudes, and are sharply overlain by a thin interval of carbonate that preserves marine carbon and sulphur isotopic excursions of about -5 and +15 parts per thousand, respectively; these deposits are thought to record widespread oceanic carbonate precipitation during postglacial sea level rise. This abrupt transition records a climate system in profound disequilibrium and contrasts sharply with the cyclical stratigraphic signal imparted by the balanced feedbacks modulating Phanerozoic deglaciation. Hypotheses accounting for the abruptness of deglaciation include ice albedo feedback, deep-ocean out-gassing during post-glacial oceanic overturn or methane hydrate destabilization. Here we report the broadest range of oxygen isotope values yet measured in marine sediments (-25 per thousand to +12 per thousand) in methane seeps in Marinoan deglacial sediments underlying the cap carbonate. This range of values is likely to be the result of mixing between ice-sheet-derived meteoric waters and clathrate-derived fluids during the flushing and destabilization of a clathrate field by glacial meltwater. The equatorial palaeolatitude implies a highly volatile shelf permafrost pool that is an order of magnitude larger than that of the present day. A pool of this size could have provided a massive biogeochemical feedback capable of triggering deglaciation and accounting for the global postglacial marine carbon and sulphur isotopic excursions, abrupt unidirectional warming, cap carbonate deposition, and a marine oxygen crisis. Our findings suggest that methane released from low-latitude permafrost clathrates therefore acted as a trigger and/or strong positive feedback for deglaciation and warming. Methane hydrate

  16. Iapetus' Geophysics: Rotation Rate, Shape, and Equatorial Ridge

    Science.gov (United States)

    Castillo-Rogez, J. C.; Matson, D. L.; Sotin, C.; Johnson, T. V.; Lunine, J. I.; Thomas, P. C.

    2007-01-01

    Iapetus has preserved evidence that constrains the modeling of its geophysical history from the time of its accretion until now. The evidence is (a) its present 79.33-day rotation or spin rate, (b) its shape that corresponds to the equilibrium figure for a hydrostatic body rotating with a period of approximately 16 h, and (c) its high, equatorial ridge, which is unique in the Solar System. This paper reports the results of an investigation into the coupling between Iapetus' thermal and orbital evolution for a wide range of conditions including the spatial distributions with time of composition, porosity, short-lived radioactive isotopes (SLRI), and temperature. The thermal model uses conductive heat transfer with temperature-dependent conductivity. Only models with a thick lithosphere and an interior viscosity in the range of about the water ice melting point can explain the observed shape. Short-lived radioactive isotopes provide the heat needed to decrease porosity in Iapetus? early history. This increases thermal conductivity and allows the development of the strong lithosphere that is required to preserve the 16-h rotational shape and the high vertical relief of the topography. Long-lived radioactive isotopes and SLRI raise internal temperatures high enough that significant tidal dissipation can start, and despin Iapetus to synchronous rotation. This occurred several hundred million years after Iapetus formed. The models also constrain the time when Iapetus formed because the successful models are critically dependent upon having just the right amount of heat added by SLRI decay in this early period. The amount of heat available from short-lived radioactivity is not a free parameter but is fixed by the time when Iapetus accreted, by the canonical concentration of Al-26, and, to a lesser extent, by the concentration of Fe-60. The needed amount of heat is available only if Iapetus accreted between 2.5 and 5.0Myr after the formation of the calcium aluminum

  17. Insulin mimetic peroxo complexes of vanadium containing uracil or Cytosine as ligand.

    Science.gov (United States)

    Sarkar, A R; Mandal, S

    2000-01-01

    Mixed ligand oxo peroxo complexes of vanadium (V), M[VO(O(2))L(2)].nH(2)O where M = K or NH(4), HL = uracil or cytosine and n = 1 or 2, have been isolated from aqueous methanolic medium. The complexes were characterised by elemental analysis, conductance, TGA, UV-Visible, IR and NMR spectral studies. Both the peroxide and the other ligands acts as chelates coordinating through their oxygen at C (2) and nitrogen at N (3) and the presence of monomeric oxoperoxovanadium (V) species, have been established by IR, (1)H and (51)V NMR studies. The complexes appeared to possess pentagonal bipyramidal geometry. The terminal oxo ligand and the oxygen of the uracil or cytosine at C (2) occupy the axial position while the peroxide and the other donor ligands are in the equatorial position. The UV spectral studies confirm the presence of Vanadium in its +5 oxidation state. The administration of the potassium salts of the complexes reduces the blood glucose level in Swiss Albino mice compared to that of KVO(3). The complexes also readily oxidise cysteine to Cystine in aqueous solution. The possible mechanism for the insulin-mimic activity of the complexes is discussed.

  18. Macrocyclic ligands for uranium complexation: Progress report, August 15, 1986--January 28, 1989

    Energy Technology Data Exchange (ETDEWEB)

    Potts, K.T.

    1989-01-28

    Macrocycles, designed for complexation of the uranyl ion by computer modeling studies and utilizing six ligating atoms in the equatorial plane of the uranyl ion, have been prepared and their ability to complex the uranyl ion evaluated. The ligating atoms, either oxygen or sulfur, were part of acylurea, biuret or thiobiuret subunits with alkane chains or pyridine units completing the macrocyclic periphery. The macrocycles studied formed uranyl complexes in solution but no crystalline complexes have been isolated to date. Acyclic ligands containing the same atoms in equivalent functional entities were found to form a crystalline 1:1 uranyl-ligand complex whose structure was established by X-ray data. This complex underwent a facile, DMSO-induced rearrangement to a 2:1 uranyl-ligand complex whose structure was also established by X-ray data. The intermediates to the macrocycles all behave as excellent ligands for the complexation of transition metals. Acylthiourea complexes of copper and nickel as well as intermolecular, binuclear copper and nickel complexes of bidentate carbonyl thioureas formed readily and their structures were established in several representative instances by X-ray structural determinations. Tetradentate bis(carbonylthioureas) were found to be very efficient selective reagents for the complexation of copper in the presence of nickel ions. 21 refs., 7 figs., 10 tabs.

  19. Novel olfactory ligands via terpene synthases.

    Science.gov (United States)

    Touchet, Sabrina; Chamberlain, Keith; Woodcock, Christine M; Miller, David J; Birkett, Michael A; Pickett, John A; Allemann, Rudolf K

    2015-05-01

    A synthetic biology approach to the rational design of analogues of olfactory ligands by providing unnatural substrates for the enzyme synthesising (S)-germacrene D, an olfactory ligand acting as a plant derived insect repellent, to produce novel ligands is described as a viable alternative to largely unsuccessful ligand docking studies. (S)-14,15-Dimethylgermacrene D shows an unexpected reversal in behavioural activity.

  20. Study on Equatorial Bubbles Detected by SPS IMS Onboard the Kompsat-I

    Directory of Open Access Journals (Sweden)

    Jaejeung Park

    2002-06-01

    Full Text Available Space Physics Sensor onboard the KOMPSAT-1, which was launched at 1999, had transmitted ionospheric data during the solar maximum from June 2000 to August 2001. When the KOMPSAT-1 has passed the equatorial region, equatorial bubbles, in which the electron density abruptly decreases, had frequently been detected. Statistical analysis of the data obtained during the entire operational period shows equatorial bubbles frequently occur across the Atlantic region where the geomagnetic field strength is weak. Also, equatorial bubbles occur more frequently for lower Kp index. The results are in good agreement with the previous observations by DMSP satellites and radio experiments at the Peruvian sector. The correlation between electron density and the electron temperature shows various behaviors from event to event.

  1. Determination of vertical velocities in the equatorial part of the western Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Bahulayan, N.; Varadachari, V.V.R.

    Using steady state two-dimensional turbulent diffusion equations of salt and heat some important characteristics of vertical circulation in the equatorial part of the Indian Ocean have been evaluated and discussed. Upwelling and sinking velocities...

  2. Weight Percentage of Calcium Carbonate for 17 Equatorial Pacific Cores from Brown University

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Weight percentages of calcium carbonate in this file were compiled by J. Farrell and W. L. Prell of Brown University for 17 equatorial Pacific Ocean sediment cores....

  3. Geology of the Venus equatorial region from Pioneer Venus radar imaging

    Science.gov (United States)

    Senske, D. A.

    1990-01-01

    The data collected by Pioneer Venus have been used to map the broad radar characteristics of the equatorial region on the basis of radar brightness and texture. Seven units are defined and are used to assess the geologic character of the equatorial region. The correspondence between features in the 15 deg region of overlap between Pioneer Venus ans Venera 15/16 images is examined and used to extend units mapped in the northern high latitudes into the equatorial region. Using the properties of rms slope, reflectivity, the scattering behavior of the surface, and topographic signature, seven physiographic units are mapped on the basis of the distribution of the radar units in the equatorial region and are identified by increasing complexity as plains, dark halo plains, upland rises, upland plateaus, interhighland tectonic zones, tectonically segmented linear highlands, and tectonic junctions. The distribution of larger circular structures interpreted as coronae is also examined.

  4. 10Be/230Th ratios as proxy for particle flux in the equatorial Pacific ocean

    International Nuclear Information System (INIS)

    Anderson, R.F.; Fleisher, M.Q.; Kubik, P.W.; Suter, M.

    1997-01-01

    Particulate 10 Be/ 230 Th ratios collected by sediment traps in the central equatorial Pacific Ocean exhibit a positive correlation with particle flux, but little or no correlation with particle composition. (author) 1 fig., 4 refs

  5. Upper ocean variability of the equatorial Indian Ocean and its relation to chlorophyll pigment concentration.

    Digital Repository Service at National Institute of Oceanography (India)

    Narvekar, J.; PrasannaKumar, S.

    Hydrographic data from the upper ocean together with atmospheric data and satellite data are used to understand the variability of upper ocean and its relation to surface chlorophyll in the Equatorial Indian Ocean. The sea surface temperature showed...

  6. Detection and Characterization of Equatorial Scintillation for Real-Time Operational Support

    National Research Council Canada - National Science Library

    McNeil, W

    1997-01-01

    The Phillips Laboratory Scintillation Network Decision Aid (PL-SCINDA) is a software tool which uses real-time data from remote sites to model ionospheric plasma depletions in the equatorial region...

  7. Central Equatorial Pacific Experiment (CEPEX) MODIS Airborne Simulator (MAS) Level-1B Data Products

    Data.gov (United States)

    National Aeronautics and Space Administration — The objective of the Central Equatorial Pacific Experiment (CEPEX) campaign was to study the effects that Cirrus cloud radiative and surface evaporation properties...

  8. Improved design of an ITER equatorial EC launcher

    International Nuclear Information System (INIS)

    Takahashi, K.; Kajiwara, K.; Kobayashi, N.; Kasugai, A.; Sakamoto, K.

    2008-01-01

    New design improvements for an ITER equatorial EC launcher are described. A design of the front shield modules was evaluated analytically. The results indicate that these modules can withstand the electromagnetic forces induced by plasma disruption and vertical plasma motion. The steering mirror mock-up including the spiral cooling tubes was fabricated based on the present design with application of the hot isostatic pressing technique to bond the copper alloy mirror body and the embedded stainless steel cooling tubes. The test of water flow was carried out and the expected flow rate was successfully obtained. A quasi-optical (QO) transmission layout has been proposed instead of the waveguide lines. The advantage of this option is possibly to increase the reliability in terms of fabrication and refurbishment. According to the beam propagation analysis, it is verified that transmission loss at the QO region is 1.1%-2.2%, which is comparable to the reference design. The peak heat load on the steering mirror surface could be reduced by 55%, which relaxes the mirror design

  9. Equatorial circular orbits in the Kerr-de Sitter spacetimes

    International Nuclear Information System (INIS)

    Stuchlik, Zdenek; Slany, Petr

    2004-01-01

    Equatorial motion of test particles in Kerr-de Sitter spacetimes is considered. Circular orbits are determined, their properties are discussed for both black-hole and naked-singularity spacetimes, and their relevance for thin accretion disks is established. The circular orbits constitute two families that coalesce at the so-called static radius. The orientation of the motion along the circular orbits is, in accordance with case of asymptotically flat Kerr spacetimes, defined by relating the motion to the locally nonrotating frames. The minus-family orbits are all counterrotating, while the plus-family orbits are usually corotating relative to these frames. However, the plus-family orbits become counterrotating in the vicinity of the static radius in all Kerr-de Sitter spacetimes, and they become counterrotating in the vicinity of the ring singularity in Kerr-de Sitter naked-singularity spacetimes with a low enough rotational parameter. In such spacetimes, the efficiency of the conversion of the rest energy into heat energy in the geometrically thin plus-family accretion disks can reach extremely high values exceeding the efficiency of the annihilation process. The transformation of a Kerr-de Sitter naked singularity into an extreme black hole due to accretion in the thin disks is briefly discussed for both the plus-family and minus-family disks. It is shown that such a conversion leads to an abrupt instability of the innermost parts of the plus-family accretion disks that can have strong observational consequences

  10. Equatorial segment of the mid-atlantic ridge

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-12-31

    The Equatorial Segment of the Mid-Atlantic Ridge is a part of this mid-oceanic ridge limited by a cluster of fracture zones - Cape Verde, Marathon, Mercury, Vema, Doldrums, Vernadsky and Sierra Leone - in the North, and a similar cluster of fracture zones - St Paul, Romanche and Chain - in the South. During recent decades, following the publication of the 5. edition of the General Bathymetric Chart of the Oceans (GEBCO), there has been a great deal of geological-geophysical research and mapping of the World Ocean. The results have led to the development of a number of theories concerning the essential heterogeneity of the structure of the ocean floor and, in particular, the heterogeneity of the structure and segmentation of mid-oceanic ridges. Research on the nature of such segmentation is of great importance for an understanding of the processes of development of such ridges and oceanic basins as a whole. Chapter 20 is dedicated to the study of the atlantic ocean mantle by using (Th.U)Th, (Th/U)pb and K/Ti systematics 380 refs.

  11. Equatorial Kelvin wave variability during 1992 and 1993

    Science.gov (United States)

    Canziani, Pablo O.; Holton, James R.; Fishbein, Evan; Froidevaux, Lucien

    1995-01-01

    Temperature and ozone data from the Microwave Limb Sounder (MLS) instrument on Upper Atmosphere Research Satellite (UARS) are used to analyze the variability of Kelvin wave activity during the first two years of the UARS mission. The analysis is carried out using the asynoptic mapping technique. Time frequency plots for zonal wavenumbers 1 and 2, at two heights representing the middle stratosphere and the stratopause, respectively, are used to analyze the temporal variability of the waves, and its possible relationship to the equatorial quasi-biennial oscillation (QBO) and semiannual oscillation (SAO). Kelvin wave activity reaches a maximum during the solstice seasons and almost disappears during the equinoxes, in agreement with previous studies. Eastward propagating variance is estimated for wave periods from 4 to 20 days, at all UARS pressure surfaces currently available for MLS. The semiannual modulation of variance is observed to extend down to the lower limits of the height ranges of the temperature and ozone retrievals. Furthermore, a superposed QBO modulation is detected up to the stratopause. Comparison between the variance in eastward propagating waves and the mean zonal wind shows a possible participation of kelvin waves in the forcing of the QBO. At the stratopause the role of Kelvin waves in forcing the SAO appears to be limited, in agreement with previous results. Between the 21-hPa and 4.6-hPa surfaces there appears to be a transition zone where there is no clear relationship between Kelvin wave activity and mean zonal flow acceleration.

  12. A Cenozoic record of the equatorial Pacific carbonate compensation depth.

    Science.gov (United States)

    Pälike, Heiko; Lyle, Mitchell W; Nishi, Hiroshi; Raffi, Isabella; Ridgwell, Andy; Gamage, Kusali; Klaus, Adam; Acton, Gary; Anderson, Louise; Backman, Jan; Baldauf, Jack; Beltran, Catherine; Bohaty, Steven M; Bown, Paul; Busch, William; Channell, Jim E T; Chun, Cecily O J; Delaney, Margaret; Dewangan, Pawan; Dunkley Jones, Tom; Edgar, Kirsty M; Evans, Helen; Fitch, Peter; Foster, Gavin L; Gussone, Nikolaus; Hasegawa, Hitoshi; Hathorne, Ed C; Hayashi, Hiroki; Herrle, Jens O; Holbourn, Ann; Hovan, Steve; Hyeong, Kiseong; Iijima, Koichi; Ito, Takashi; Kamikuri, Shin-ichi; Kimoto, Katsunori; Kuroda, Junichiro; Leon-Rodriguez, Lizette; Malinverno, Alberto; Moore, Ted C; Murphy, Brandon H; Murphy, Daniel P; Nakamura, Hideto; Ogane, Kaoru; Ohneiser, Christian; Richter, Carl; Robinson, Rebecca; Rohling, Eelco J; Romero, Oscar; Sawada, Ken; Scher, Howie; Schneider, Leah; Sluijs, Appy; Takata, Hiroyuki; Tian, Jun; Tsujimoto, Akira; Wade, Bridget S; Westerhold, Thomas; Wilkens, Roy; Williams, Trevor; Wilson, Paul A; Yamamoto, Yuhji; Yamamoto, Shinya; Yamazaki, Toshitsugu; Zeebe, Richard E

    2012-08-30

    Atmospheric carbon dioxide concentrations and climate are regulated on geological timescales by the balance between carbon input from volcanic and metamorphic outgassing and its removal by weathering feedbacks; these feedbacks involve the erosion of silicate rocks and organic-carbon-bearing rocks. The integrated effect of these processes is reflected in the calcium carbonate compensation depth, which is the oceanic depth at which calcium carbonate is dissolved. Here we present a carbonate accumulation record that covers the past 53 million years from a depth transect in the equatorial Pacific Ocean. The carbonate compensation depth tracks long-term ocean cooling, deepening from 3.0-3.5 kilometres during the early Cenozoic (approximately 55 million years ago) to 4.6 kilometres at present, consistent with an overall Cenozoic increase in weathering. We find large superimposed fluctuations in carbonate compensation depth during the middle and late Eocene. Using Earth system models, we identify changes in weathering and the mode of organic-carbon delivery as two key processes to explain these large-scale Eocene fluctuations of the carbonate compensation depth.

  13. Equatorial segment of the mid-atlantic ridge

    International Nuclear Information System (INIS)

    1996-01-01

    The Equatorial Segment of the Mid-Atlantic Ridge is a part of this mid-oceanic ridge limited by a cluster of fracture zones - Cape Verde, Marathon, Mercury, Vema, Doldrums, Vernadsky and Sierra Leone - in the North, and a similar cluster of fracture zones - St Paul, Romanche and Chain - in the South. During recent decades, following the publication of the 5. edition of the General Bathymetric Chart of the Oceans (GEBCO), there has been a great deal of geological-geophysical research and mapping of the World Ocean. The results have led to the development of a number of theories concerning the essential heterogeneity of the structure of the ocean floor and, in particular, the heterogeneity of the structure and segmentation of mid-oceanic ridges. Research on the nature of such segmentation is of great importance for an understanding of the processes of development of such ridges and oceanic basins as a whole. Chapter 20 is dedicated to the study of the atlantic ocean mantle by using (Th.U)Th, (Th/U)pb and K/Ti systematics

  14. Climatic Variation at Thumba Equatorial Rocket Launching Station, India

    Directory of Open Access Journals (Sweden)

    K. V. S. Namboodiri

    2013-01-01

    Full Text Available Long-term (45 years diversified surface meteorological records from Thumba Equatorial Rocket Launching Station (TERLS, India, were collected and analysed to study the long-term changes in the overall climatology, climatology pertained to a particular observational time, mean daily climatology in temperature, inter-annual variability in temperature, interannual variability in surface pressure, and rainfall for the main Indian seasons—South West and North East monsoons and inter-annual mean monthly anomaly structure in temperature. Results on various analyses show strong and vivid features contributed by climate change for this South Peninsular Indian Arabian Sea Coastal Station, and this paper may be a first time venture which discusses climate change imparted perturbations in several meteorological parameters in different time domains, like a specific time, daily, monthly, and interannually over a station. Being a coastal rocket launching station, climatic change information is crucial for long-term planning of its facilities as well as for various rocket range operational demands.

  15. Climate extremes in Malaysia and the equatorial South China Sea

    Science.gov (United States)

    Salahuddin, Ahmed; Curtis, Scott

    2011-08-01

    The southern extent of the South China Sea (SCS) is an important natural resource epicenter for Malaysia which experiences climate extremes. This paper documents the variability of extremes in the equatorial SCS through selected ground-based observations of precipitation in Malaysia and ship-based observations of wind data in the Maritime Continent region, to elucidate the interrelationship between precipitation variability over Malaysia and wind variability over the ocean. The data have been carefully inspected and analyzed, and related to the real-time multivariate Madden-Julian Oscillation (MJO) time series. The analysis suggests that the northeast or boreal winter monsoon dominates extreme rainfall in eastern Malaysian cities. Further, the west coast of Peninsular Malaysia and Borneo Malaysia are affected by the MJO differently than the east coast of Peninsular Malaysia. From the wind analysis we found that average zonal wind is westerly from May to September and easterly from November to April. When the active (convective) phase of the MJO is centered over the Maritime Continent, the strong westerly wind bursts are more frequent in the South China Sea. While more investigation is needed, these results suggest that the status of the Madden-Julian Oscillation can be used to help forecast climate extremes in areas of Malaysia.

  16. Seasonal Variation of the North/South Equatorial Current Bifurcation

    Science.gov (United States)

    Chen, Z.

    2016-02-01

    The seasonal variation of the North/South Equatorial Current (NEC/SEC) bifurcation off the Philippine/Madagascar/Australian coast is investigated. It is shown that the seasonal cycles of the NEC/SEC bifurcation are generally analogous to each other, all of which shift synchronously back and forth seasonally and arrive at their southernmost positions in boreal late spring and early summer. It is demonstrated that the linear, reduced gravity, long Rossby model, which works well for the NEC bifurcation, is insufficient to reproduce the seasonal cycles of the SEC bifurcation off the Madagascar/Australian coast particularly in their south-north migrations. This can be attributed to the existence of the isolated island in the Madagascar case and the seasonally-varying wind forcing around the Australian coast, while they are almost absent in the NEC bifurcation case. Without considering the existence of an island and the alongshore winds, we propose a simple bifurcation model under the framework of linear Rossby wave dynamics. It is found that the seasonal bifurcation latitude is predominantly determined by the spatial pattern of the wind and baroclinic Rossby wave propagation. This model explains the roles of local/remote wind forcing and baroclinic adjustment in the south-north migration and peak seasons of the bifurcation latitude.

  17. Stormtime dynamics of the global thermosphere and equatorial ionosphere

    Directory of Open Access Journals (Sweden)

    W. J. Burke

    2009-05-01

    Full Text Available During magnetic storms the development of equatorial plasma bubbles (EPBs and distributions of thermospheric densities are strongly influenced by the histories of imposed magnetospheric electric (εM fields. Periods of intense EPB activity driven by penetration εM fields in the main phase are followed by their worldwide absence during recovery. A new method is applied to estimate global thermospheric energy (Eth budgets from orbit-averaged densities measured by accelerometers on polar-orbiting satellites. During the main phase of storms Eth increases as long as the stormtime εM operates, then exponentially decays toward quiet-time values during early recovery. Some fraction of the energy deposited at high magnetic latitudes during the main phase propagates into the subauroral ionosphere-thermosphere where it affects chemical and azimuthal-wind dynamics well into recovery. We suggest a scenario wherein fossils of main phase activity inhibit full restoration of quiet-time dayside dynamos and pre-reversal enhancements of upward plasma drifts near dusk denying bottomside irregularities sufficient time to grow into EPBs.

  18. Stormtime dynamics of the global thermosphere and equatorial ionosphere

    Directory of Open Access Journals (Sweden)

    W. J. Burke

    2009-05-01

    Full Text Available During magnetic storms the development of equatorial plasma bubbles (EPBs and distributions of thermospheric densities are strongly influenced by the histories of imposed magnetospheric electric (εM fields. Periods of intense EPB activity driven by penetration εM fields in the main phase are followed by their worldwide absence during recovery. A new method is applied to estimate global thermospheric energy (Eth budgets from orbit-averaged densities measured by accelerometers on polar-orbiting satellites. During the main phase of storms Eth increases as long as the stormtime εM operates, then exponentially decays toward quiet-time values during early recovery. Some fraction of the energy deposited at high magnetic latitudes during the main phase propagates into the subauroral ionosphere-thermosphere where it affects chemical and azimuthal-wind dynamics well into recovery. We suggest a scenario wherein fossils of main phase activity inhibit full restoration of quiet-time dayside dynamos and pre-reversal enhancements of upward plasma drifts near dusk denying bottomside irregularities sufficient time to grow into EPBs.

  19. Axial-equatorial isomerism and semiexperimental equilibrium structures of fluorocyclohexane.

    Science.gov (United States)

    Juanes, Marcos; Vogt, Natalja; Demaison, Jean; León, Iker; Lesarri, Alberto; Rudolph, Heinz Dieter

    2017-11-08

    An experimental-computational methodology combining rotational data, high-level ab initio calculations and predicate least-squares fitting is applied to the axial-equatorial isomerism and semiexperimental equilibrium structure determination of fluorocyclohexane. New supersonic-jet microwave measurements of the rotational spectra of the two molecular conformations, together with all 13 C isotopologues of both isomeric forms are reported. Equilibrium rotational constants are obtained from the ground-state rotational constants corrected for vibration-rotation interactions and electronic contributions. Equilibrium structures were determined by the mixed estimation (ME) method. Different computational methods were tested for the evaluation of predicate values of the structural parameters, and a computationally effective procedure for estimating reliable dihedral angles is proposed. Structural parameters were fitted concurrently to predicate parameters and moments of inertia, affected with appropriate uncertainties. The new structures of the title compound are regarded as accurate to 0.001 Å and 0.2°, illustrating the advantages of this methodology. Structural comparisons are offered with the cyclohexane prototype, revealing subtle substituent effects. For comparison purposes the equilibrium structures for the two fluorocyclohexane isomers and cyclohexanone are computed from high-level ab initio theory with inclusion of adjustments for basis set dependence and correlation of the core electrons.

  20. The field of the equatorial electrojet from CHAMP data

    Directory of Open Access Journals (Sweden)

    J.-L. Le Mouël

    2006-03-01

    Full Text Available We apply a simple linear transform, the along-track second derivative, to four years of scalar and vectorial data from the CHAMP satellite. This transform, reminiscent of techniques used in the interpretation of aeromagnetic surveys, is applied either to the geocentric spherical components of the field or to its intensity. After averaging in time and space, we first produce a map of the crustal field, then maps of the equatorial electrojet field at all local times and all universal times. The seasonal variation of the electrojet, its evolution with the solar cycle, and the effect of geomagnetic activity are discussed. The variation of the electrojet with longitude, an intriguing feature revealed by satellite data, is described in some detail, and it is shown that this longitude dependance is stable in time. The existence of a counterelectrojet in the morning, everywhere except over the Pacific Ocean, is established. The signatures of closure electric currents and of interhemispheric currents are also evidenced.

  1. Sexual harassment and emotional and behavioural symptoms in adolescence: stronger associations among boys than girls.

    Science.gov (United States)

    Kaltiala-Heino, Riittakerttu; Fröjd, Sari; Marttunen, Mauri

    2016-08-01

    To study the associations between subjection to sexual harassment and emotional (depression) and behavioural (delinquency) symptoms among 14-to-18-year-old adolescents, and gender differences within these associations. 90,953 boys and 91,746 girls aged 14-18 participated in the School Health Promotion Study (SHPS), a school-based survey designed to examine the health, health behaviours, and school experiences of teenagers. Experiences of sexual harassment were elicited with five questions addressing five separate forms of harassment. Depression was measured by the 13-item Beck Depression Inventory and delinquency with a modified version of the International Self-Report Delinquency Study (ISRD) instrument. Data were analysed using cross-tabulations with Chi-square statistics and logistic regression. All sexual harassment experiences studied were associated with both depression (adjusted odds ratios varied from 2.2 to 2.7 in girls and from 2.0 to 5.1 in boys) and delinquency (adjusted odds ratios 3.1-5.0 in girls and 1.7-6.9 in boys). Sexual name-calling had a stronger association with depression and with delinquency in girls (adjusted odds ratios, respectively, 2.4 and 4.2), than in boys (adjusted odds ratios, respectively, 2.0 and 1.7), but otherwise stronger associations with emotional and behavioural symptoms were seen in boys. Subjection to sexual harassment is associated with both emotional and behavioural symptoms in both girls and boys. The associations are mostly stronger for boys. Boys subjected to sexual harassment may feel particularly threatened regarding their masculinity, and there may be less support available for boys traumatised due to sexual harassment.

  2. The effect of J2 on equatorial and halo orbits around a magnetic planet

    International Nuclear Information System (INIS)

    Inarrea, Manuel; Lanchares, Victor; Palacian, Jesus F.; Pascual, Ana I.; Pablo Salas, J.; Yanguas, Patricia

    2009-01-01

    We calculate equatorial and halo orbits around a non-spherical (both oblate and prolate) magnetic planet. It is known that circular equatorial and halo orbits exist for a dust grain orbiting a spherical magnetic planet. However, the frequency of the orbit is constrained by the charge-mass ratio of the particle. If the non-sphericity of the planet is taken into account this constraint is modified or, in some cases, it disappears.

  3. The effect of J{sub 2} on equatorial and halo orbits around a magnetic planet

    Energy Technology Data Exchange (ETDEWEB)

    Inarrea, Manuel [Universidad de la Rioja, Area de Fisica, 26006 Logrono (Spain); Lanchares, Victor [Dpto. de Matematicas y Computacion, CIEMUR: Centro de Investigacion en Informatica, Estadistica y Matematicas, Universidad de la Rioja, 26004 Logrono (Spain)], E-mail: vlancha@unirioja.es; Palacian, Jesus F. [Universidad Publica de Navarra, Departamento de Ingenieria Matematica e Informatica, 31006 Pamplona (Spain); Pascual, Ana I. [Dpto. de Matematicas y Computacion, CIEMUR: Centro de Investigacion en Informatica, Estadistica y Matematicas, Universidad de la Rioja, 26004 Logrono (Spain); Pablo Salas, J. [Universidad de la Rioja, Area de Fisica, 26006 Logrono (Spain); Yanguas, Patricia [Universidad Publica de Navarra, Departamento de Ingenieria Matematica e Informatica, 31006 Pamplona (Spain)

    2009-10-15

    We calculate equatorial and halo orbits around a non-spherical (both oblate and prolate) magnetic planet. It is known that circular equatorial and halo orbits exist for a dust grain orbiting a spherical magnetic planet. However, the frequency of the orbit is constrained by the charge-mass ratio of the particle. If the non-sphericity of the planet is taken into account this constraint is modified or, in some cases, it disappears.

  4. Biogeochemical impact of a model western iron source in the Pacific Equatorial Undercurrent

    OpenAIRE

    Slemons, L.; Gorgues, T.; Aumont, Olivier; Menkès, Christophe; Murray, J. W.

    2009-01-01

    Trace element distributions in the source waters of the Pacific Equatorial Undercurrent (EUC) show the existence of elevated total acid-soluble iron concentrations. This region has been suggested to contribute enough bioavailable iron to regulate interannual and interglacial variability in biological productivity downstream in the high-nitrate low-chlorophyll upwelling zone of the eastern equatorial Pacific. We investigated the advection and first-order biogeochemical impact of an imposed, da...

  5. Building Stronger State Energy Partnerships with the U.S. Department of Energy

    Energy Technology Data Exchange (ETDEWEB)

    David Terry

    2008-09-30

    This final technical report details the results of total work efforts and progress made from July 2000 - July 2008 under the National Association of State Energy Officials (NASEO) cooperative agreement DE-FC26-00NT40802, Building Stronger State Energy Partnerships with the U.S. Department of Energy. Major topical project areas in this final report include work efforts in the following areas: Rebuild America/Energy Smart Schools, Higher Education Initiative, Winter/Summer Fuels Outlook Conferences, Energy Emergency, Clean Energy Integration, Energy Star, and Office of Electricity Delivery and Energy Reliability. All required deliverables have been provided to the National Energy Technology Laboratory and DOE program officials.

  6. The University of Florida Department of Surgery: building a stronger tomorrow on yesterday's foundation.

    Science.gov (United States)

    Behrns, Kevin E; Copeland, Edward M; Howard, Richard J

    2012-01-01

    Established in 1957, the University of Florida Department of Surgery has a solid foundation on which current faculty are driven to build a stronger tomorrow. The department is focused on promoting patient-centered care, expanding its research portfolio to improve techniques and outcomes, and training the surgical leaders of tomorrow. It fosters an environment where faculty, residents, students, and staff challenge long-held traditions with the goal of improving the health of our patients, the quality of our care, and the vitality of our work environment.

  7. Production of plastified wood with stronger static bending strength means of polymerization induced by gamma radiation

    International Nuclear Information System (INIS)

    Silva Filho, Elias

    1999-01-01

    The use of gamma radiation to obtain wood-polymer composites is one of the applications of radiation that presents the most commercial interest. The process, denominated radiopolymerization, comprises the impregnation of monomers into the completely dried wood followed by exposure to gamma radiation to induce polymerization of the impregnated monomers. I this context, the present work aimed the application of this process to seven kinds of wood existing in the brazilian forests. The considered monomer is styrene and the gamma source is Cobalt-60. The obtained wood-polystyrene composites were found to have stronger static bending strength. (author)

  8. Building Stronger State Energy Partnerships with the U.S. Department of Energy

    Energy Technology Data Exchange (ETDEWEB)

    Marks, Kate

    2011-09-30

    This final technical report details the results of total work efforts and progress made from October 2007 – September 2011 under the National Association of State Energy Officials (NASEO) cooperative agreement DE-FC26-07NT43264, Building Stronger State Energy Partnerships with the U.S. Department of Energy. Major topical project areas in this final report include work efforts in the following areas: Energy Assurance and Critical Infrastructure, State and Regional Technical Assistance, Regional Initiative, Regional Coordination and Technical Assistance, and International Activities in China. All required deliverables have been provided to the National Energy Technology Laboratory and DOE program officials.

  9. Association between mean and interannual equatorial Indian Ocean subsurface temperature bias in a coupled model

    Science.gov (United States)

    Srinivas, G.; Chowdary, Jasti S.; Gnanaseelan, C.; Prasad, K. V. S. R.; Karmakar, Ananya; Parekh, Anant

    2018-03-01

    In the present study the association between mean and interannual subsurface temperature bias over the equatorial Indian Ocean (EIO) is investigated during boreal summer (June through September; JJAS) in the National Centers for Environmental Prediction (NCEP) Climate Forecast System (CFSv2) hindcast. Anomalously high subsurface warm bias (greater than 3 °C) over the eastern EIO (EEIO) region is noted in CFSv2 during summer, which is higher compared to other parts of the tropical Indian Ocean. Prominent eastward current bias in the upper 100 m over the EIO region induced by anomalous westerly winds is primarily responsible for subsurface temperature bias. The eastward currents transport warm water to the EEIO and is pushed down to subsurface due to downwelling. Thus biases in both horizontal and vertical currents over the EIO region support subsurface warm bias. The evolution of systematic subsurface warm bias in the model shows strong interannual variability. These maximum subsurface warming episodes over the EEIO are mainly associated with La Niña like forcing. Strong convergence of low level winds over the EEIO and Maritime continent enhanced the westerly wind bias over the EIO during maximum warming years. This low level convergence of wind is induced by the bias in the gradient in the mean sea level pressure with positive bias over western EIO and negative bias over EEIO and parts of western Pacific. Consequently, changes in the atmospheric circulation associated with La Niña like conditions affected the ocean dynamics by modulating the current bias thereby enhancing the subsurface warm bias over the EEIO. It is identified that EEIO subsurface warming is stronger when La Niña co-occurred with negative Indian Ocean Dipole events as compared to La Niña only years in the model. Ocean general circulation model (OGCM) experiments forced with CFSv2 winds clearly support our hypothesis that ocean dynamics influenced by westerly winds bias is primarily

  10. The day-to-day occurrence of equatorial plasma bubbles measured from Vanimo, Papua New Guinea

    Science.gov (United States)

    Carter, B. A.; Yizengaw, E.; Francis, M.; Terkildsen, M. B.; Marshall, R. A.; Norman, R.; Zhang, K.

    2013-12-01

    An analysis of the occurrence of Equatorial Plasma Bubbles (EPBs) detected using a ground-based Global Positioning System (GPS) receiver located at Vanimo in South-east Asia will be presented. The 3-year (2000-2002) dataset employed shows that the EPB occurrence maximizes (minimizes) during the equinoxes (solstices), in good agreement with previous findings. The low-latitude ionosonde station at Vanimo is used in conjunction with the GPS receiver in an analysis of the day-to-day EPB occurrence variability during the equinox period. A superposed epoch analysis of the ionosonde data reveals that the height, and the change in height, of the F layer is 1 standard deviation (1σ) larger on the days for which EPBs were detected, compared to non-EPB days. These results are interpreted using the generalized Rayleigh-Taylor (R-T) plasma instability growth rate, for which stronger upward drift of the lower-altitude F-layer plasma promotes faster growth of EPBs after sunset. These results are then compared to the results of the Thermosphere Ionosphere Electrodynamic General Circulation Model (TIEGCM), which surprisingly show strong similarities to the observations, despite only using geomagnetic and solar activity inputs. The TIEGCM is also used to directly calculate the hourly flux-tube integrated R-T growth rate. A superposed epoch analysis reveals that the modeled R-T growth rate is a little less than 1σ higher on average for EPB days compared to non-EPB days. The implication of this result is that the TIEGCM generates almost enough day-to-day variability in order to account for the day-to-day EPB occurrence observed during the equinox. This result isn't necessarily expected due to the model's limited altitude coverage of 100-700 km (depending on solar activity) and the lack of ionospheric observation inputs. It is thought that the remaining variability could originate from either lower altitudes (e.g. atmospheric gravity waves from the troposphere) or from higher

  11. Equatorial electrojet as part of the global circuit: a case-study from the IEEY

    Directory of Open Access Journals (Sweden)

    A. T. Kobea

    1998-06-01

    Full Text Available Geomagnetic storm-time variations often occur coherently at high latitude and the day-side dip equator where they affect the normal eastward Sq field. This paper presents an analysis of ground magnetic field and ionospheric electrodynamic data related to the geomagnetic storm which occured on 27 May 1993 during the International Equatorial Electrojet Year (IEEY experiment. This storm-signature analysis on the auroral, mid-latitude and equatorial ground field and ionospheric electrodynamic data leads to the identification of a sensitive response of the equatorial electrojet (EEJ to large-scale auroral return current: this response consists in a change of the eastward electric field during the pre-sunrise hours (0400-0600 UT coherently to the high-, mid-, and equatorial-latitude H decrease and the disappearance of the EEJ irregularities between the time-interval 0800-0950 UT. Subsequent to the change in h'F during pre-sunrise hours, the observed foF2 increase revealed an enhancement of the equatorial ionization anomaly (EIA caused by the high-latitude penetrating electric field. The strengthening of these irregularities attested by the Doppler frequency increase tracks the H component at the equator which undergoes a rapid increase around 0800 UT. The ∆H variations observed at the equator are the sum of the following components: SR, DP, DR, DCF and DT.Keywords. Equatorial electrojet · Magnetosphere-ionosphere interactions · Electric fields and currents · Auroral ionosphere · Ionospheric disturbances

  12. Do External or Internal Technology Spillovers Have a Stronger Influence on Innovation Efficiency in China?

    Directory of Open Access Journals (Sweden)

    Xionghe Qin

    2017-09-01

    Full Text Available In this study, we bridge an important gap in the literature by comparing the extent to which external technology spillovers, as indicated by foreign direct investment (FDI, and internal technology spillovers, as indicated by university-institute-industry cooperation (UIC, influence innovation efficiency in China. We divide the innovation process into two sequential stages, namely the knowledge creation and technology commercialization stages, and employ a network data envelopment analysis approach to measure innovation efficiency at each stage. The spatial analysis of the distribution of knowledge creation efficiency and technology commercialization efficiency reveals the heterogeneity of innovation efficiency at the provincial level. Then, a panel data regression is used to analyze the effect of FDI and UIC on innovation efficiency at each stage, using data from 2009 to 2015 for 30 provinces in China. By comparing FDI with UIC, we find that FDI has a higher coefficient and stronger significance level at the knowledge creation stage, while only industry-institute linkages exhibit a stronger association with innovation efficiency at the technology commercialization stage.

  13. The El Niño Southern Oscillation is Getting Bigger and Stronger

    Science.gov (United States)

    McNaught, C.; O'Brien, J.; Strazzo, S. E.

    2012-12-01

    The El Niño Southern Oscillation (ENSO) is an important natural climate variation that affects large portions of the world. We measure ENSO both in terms of its frequency and its magnitude. The different phases of ENSO - El Niño and La Niña - have different properties, and impact the global weather pattern differently. We examine the hypothesis that ENSO's frequency distribution is changing. We demonstrate that, indeed, El Niño's are getting stronger as measured by the maximum anomaly in sea surface temperature (SST). An analysis of the ENSO principal component is conducted using a fast Fourier transform to estimate the spectrum of the SST of the time series. We conclude that the intensity of El Niño events during the period 1970-2010 is statistically significantly higher when compared to the 1930—1970, with a broad spectral peak centered around 4 years. When we compare the SST spectrum for the period 1930-1970 with the spectrum for 1971- 2010, we find the latter period to be much stronger in power. Additionally recently classified ENSO types, including El Niño Modoki and Warm Pool ENSO, are briefly studied.; The first empirical orthogonal function of sea-surface temperatures (1930-2010) accounting for 75% of the variance. The values are indicative of departures from the mean, in °C. Positive (negative) values indicate anomalously higher (lower) sea-surface temperatures ; Normalized first principal component

  14. Stronger interference from distractors in the right hemifield during visual search.

    Science.gov (United States)

    Carlei, Christophe; Kerzel, Dirk

    2018-03-01

    The orientation-bias hypothesis states that there is a bias to attend to the right visual hemifield (RVF) when there is spatial competition between stimuli in the left and right hemifield [Pollmann, S. (1996). A pop-out induced extinction-like phenomenon in neurologically intact subjects. Neuropsychologia, 34(5), 413-425. doi: 10.1016/0028-3932(95)00125-5 ]. In support of this hypothesis, stronger interference was reported for RVF distractors with contralateral targets. In contrast, previous studies using rapid serial visual presentation (RSVP) found stronger interference from distractors in the left visual hemifield (LVF). We used the additional singleton paradigm to test whether this discrepancy was due to the different distractor features that were employed (colour vs. orientation). Interference from the colour distractor with contralateral targets was larger in the RVF than in the LVF. However, the asymmetrical interference disappeared when observers had to search for an inconspicuous colour target instead of the inconspicuous shape target. We suggest that the LVF orienting-bias is limited to situations where search is driven by bottom-up saliency (singleton search) instead of top-down search goals (feature search). In contrast, analysis of the literature suggests the opposite for the LVF bias in RSVP tasks. Thus, the attentional asymmetry may depend on whether the task involves temporal or spatial competition, and whether search is based on bottom-up or top-down signals.

  15. When surging seas meet stronger rain: Nuclear techniques in flood management

    International Nuclear Information System (INIS)

    Quevenco, Rodolfo

    2015-01-01

    Unusually high rainfall in many parts of the world is a result of climate change, scientists say. Since warmer air can hold more water, the rationale goes, increased temperatures will increase the chances of stronger rainfall events. And when surging seas combine with stronger rain, the outcome is almost certain: floods. Floods are the most frequently occurring natural disasters, and south-east Asia is particularly vulnerable. Climate change and variability are expected to bring about increased typhoon activities, rising sea levels and off-season monsoon rains in southeast Asia and other regions. These can cause devastating floods in countries like Cambodia, Laos, Pakistan, the Philippines, Thailand and Viet Nam. For the residents of these countries who have survived the ravages of major floods, the road to recovery can be long and arduous. As the flood water recedes, they have to contend with new forms of flood: floods of concern and worries as to how to rebuild their houses, their lives and their cities. Governments, too, face huge challenges in rebuilding roads, public buildings, infrastructure and natural resources destroyed or polluted by the flood.

  16. Understanding M-ligand bonding and mer-/fac-isomerism in tris(8-hydroxyquinolinate) metallic complexes.

    Science.gov (United States)

    Lima, Carlos F R A C; Taveira, Ricardo J S; Costa, José C S; Fernandes, Ana M; Melo, André; Silva, Artur M S; Santos, Luís M N B F

    2016-06-28

    Tris(8-hydroxyquinolinate) metallic complexes, Mq3, are one of the most important classes of organic semiconductor materials. Herein, the nature of the chemical bond in Mq3 complexes and its implications on their molecular properties were investigated by a combined experimental and computational approach. Various Mq3 complexes, resulting from the alteration of the metal and substitution of the 8-hydroxyquinoline ligand in different positions, were prepared. The mer-/fac-isomerism in Mq3 was explored by FTIR and NMR spectroscopy, evidencing that, irrespective of the substituent, mer- and fac-are the most stable molecular configurations of Al(iii) and In(iii) complexes, respectively. The relative M-ligand bond dissociation energies were evaluated experimentally by electrospray ionization tandem mass spectrometry (ESI-MS-MS), showing a non-monotonous variation along the group (Al > In > Ga). The results reveal a strong covalent character in M-ligand bonding, which allows for through-ligand electron delocalization, and explain the preferred molecular structures of Mq3 complexes as resulting from the interplay between bonding and steric factors. The mer-isomer reduces intraligand repulsions, being preferred for smaller metals, while the fac-isomer is favoured for larger metals where stronger covalent M-ligand bonds can be formed due to more extensive through-ligand conjugation mediated by metal "d" orbitals.

  17. Magnetospheric conditions near the equatorial footpoints of proton isotropy boundaries

    Directory of Open Access Journals (Sweden)

    V. A. Sergeev

    2015-12-01

    Full Text Available Data from a cluster of three THEMIS (Time History of Events and Macroscale Interactions during Substorms spacecraft during February–March 2009 frequently provide an opportunity to construct local data-adaptive magnetospheric models, which are suitable for the accurate mapping along the magnetic field lines at distances of 6–9 Re in the nightside magnetosphere. This allows us to map the isotropy boundaries (IBs of 30 and 80 keV protons observed by low-altitude NOAA POES (Polar Orbiting Environmental Satellites to the equatorial magnetosphere (to find the projected isotropy boundary, PIB and study the magnetospheric conditions, particularly to evaluate the ratio KIB (Rc/rc; the magnetic field curvature radius to the particle gyroradius in the neutral sheet at that point. Special care is taken to control the factors which influence the accuracy of the adaptive models and mapping. Data indicate that better accuracy of an adaptive model is achieved when the PIB distance from the closest spacecraft is as small as 1–2 Re. For this group of most accurate predictions, the spread of KIB values is still large (from 4 to 32, with the median value KIB ~13 being larger than the critical value Kcr ~ 8 expected at the inner boundary of nonadiabatic angular scattering in the current sheet. It appears that two different mechanisms may contribute to form the isotropy boundary. The group with K ~ [4,12] is most likely formed by current sheet scattering, whereas the group having KIB ~ [12,32] could be formed by the resonant scattering of low-energy protons by the electromagnetic ion-cyclotron (EMIC waves. The energy dependence of the upper K limit and close proximity of the latter event to the plasmapause locations support this conclusion. We also discuss other reasons why the K ~ 8 criterion for isotropization may fail to work, as well as a possible relationship between the two scattering mechanisms.

  18. Engineering activities on the ITER representative diagnostic equatorial port plug

    International Nuclear Information System (INIS)

    Meunier, L.; Doceul, L.; Salasca, S.; Martins, J.-P.; Jullien, F.; Dechelle, Christian; Bidaud, Pierre; Pilard, Vincent; Terra, Alexis; Ogea, Mathieu; Ciattaglia, Emanuela; Walker, Christopher

    2009-01-01

    Most of ITER diagnostic systems are integrated in port plugs, which are water cooled stainless steel structures inserted into the vacuum vessel ports. The port plug must provide basic functions such as neutron and gamma shielding, supporting the first wall armour (BSM), closing the vacuum vessel ports, while supporting the diagnostic equipments. ITER diagnostic port plug must resist a severe environment like high temperature due to neutron interaction with the structures and high electromechanical loading during disruptions events. CEA has contributed to the design and integration tasks in the frame of the representative equatorial port plug EQ no. 01, in particular on the engineering, structural and thermal finite element analysis. These detailed analyses have highlighted some design issues which were worked out through different solutions. This paper contains a description of the engineering activities performed such as: -The static mechanical calculations of the top plate closure system under disruption load. -The static mechanical calculations of the BSM attachment to the port plug. These two first studies led to design changes proposals which significantly improved the behaviour of the structures but also showed that the safety margin with respect to design limits is quite low. -The design of a Diagnostic Shield Module (DSM) integrated inside the port plug and a proposition of attachment scheme, with respect to disruption loads. The manufacturing of the DSM has been taken into account, as well as diagnostic integration inside the structure and maintenance aspects. -The thermal assessment of the port plug under neutronic load during normal operation, with the optimization of the cooling system. The maximum temperature calculated in normal operation has been reduced from 900 deg. C to less than 400 deg. C in the front plate; and the cooling arrangement at the back of the port plug has been simplified without important temperature increase.

  19. Engineering activities on the ITER representative diagnostic equatorial port plug

    Energy Technology Data Exchange (ETDEWEB)

    Meunier, L. [Association Euratom CEA, CEA/DSM/IRFM (France)], E-mail: lmeunier@cea.fr; Doceul, L.; Salasca, S.; Martins, J.-P.; Jullien, F.; Dechelle, Christian; Bidaud, Pierre; Pilard, Vincent; Terra, Alexis; Ogea, Mathieu [Association Euratom CEA, CEA/DSM/IRFM (France); Ciattaglia, Emanuela [EFDA CSU, Garching (Germany); Walker, Christopher [ITER International Organisation (France)

    2009-06-15

    Most of ITER diagnostic systems are integrated in port plugs, which are water cooled stainless steel structures inserted into the vacuum vessel ports. The port plug must provide basic functions such as neutron and gamma shielding, supporting the first wall armour (BSM), closing the vacuum vessel ports, while supporting the diagnostic equipments. ITER diagnostic port plug must resist a severe environment like high temperature due to neutron interaction with the structures and high electromechanical loading during disruptions events. CEA has contributed to the design and integration tasks in the frame of the representative equatorial port plug EQ no. 01, in particular on the engineering, structural and thermal finite element analysis. These detailed analyses have highlighted some design issues which were worked out through different solutions. This paper contains a description of the engineering activities performed such as: -The static mechanical calculations of the top plate closure system under disruption load. -The static mechanical calculations of the BSM attachment to the port plug. These two first studies led to design changes proposals which significantly improved the behaviour of the structures but also showed that the safety margin with respect to design limits is quite low. -The design of a Diagnostic Shield Module (DSM) integrated inside the port plug and a proposition of attachment scheme, with respect to disruption loads. The manufacturing of the DSM has been taken into account, as well as diagnostic integration inside the structure and maintenance aspects. -The thermal assessment of the port plug under neutronic load during normal operation, with the optimization of the cooling system. The maximum temperature calculated in normal operation has been reduced from 900 deg. C to less than 400 deg. C in the front plate; and the cooling arrangement at the back of the port plug has been simplified without important temperature increase.

  20. Modeling Tides, Planetary Waves, and Equatorial Oscillations in the MLT

    Science.gov (United States)

    Mengel, J. G.; Mayr, H. G.; Drob, D. P.; Porter, H. S.; Bhartia, P. K. (Technical Monitor)

    2001-01-01

    Applying Hines Doppler Spread Parameterization for gravity waves (GW), our 3D model reproduces some essential features that characterize the observed seasonal variations of tides and planetary waves in the upper mesosphere. In 2D, our model also reproduces the large Semi-Annual Oscillation (SAO) and Quasi Biennial Oscillation (QBO) observed in this region at low latitudes. It is more challenging to describe these features combined in a more comprehensive self consistent model, and we give a progress report that outlines the difficulties and reports some success. In 3D, the GW's are partially absorbed by tides and planetary waves to amplify them. Thus the waves are less efficient in generating the QBO and SAO at equatorial latitudes. Some of this deficiency is compensated by the fact that the GW activity is observed to be enhanced at low latitudes. Increasing the GW source has the desired effect to boost the QBO, but the effect is confined primarily to the stratosphere. With increasing altitude, the meridional circulation becomes more important in redistributing the momentum deposited in the background flow by the GW's. Another factor involved is the altitude at which the GW's originate, which we had originally chosen to be the surface. Numerical experiments show that moving this source altitude to the top of the troposphere significantly increases the efficiency for generating the QBO without affecting much the tides and planetary waves in the model. Attention to the details in which the GW source comes into play thus appears to be of critical importance in modeling the phenomenology of the MLT. Among the suite of numerical experiments reported, we present a simulation that produced significant variations of tides and planetary waves in the upper mesosphere. The effect is related to the QBO generated in the model, and GW filtering is the likely cause.

  1. Coral settlement on a highly disturbed equatorial reef system.

    Science.gov (United States)

    Bauman, Andrew G; Guest, James R; Dunshea, Glenn; Low, Jeffery; Todd, Peter A; Steinberg, Peter D

    2015-01-01

    Processes occurring early in the life stages of corals can greatly influence the demography of coral populations, and successful settlement of coral larvae that leads to recruitment is a critical life history stage for coral reef ecosystems. Although corals in Singapore persist in one the world's most anthropogenically impacted reef systems, our understanding of the role of coral settlement in the persistence of coral communities in Singapore remains limited. Spatial and temporal patterns of coral settlement were examined at 7 sites in the southern islands of Singapore, using settlement tiles deployed and collected every 3 months from 2011 to 2013. Settlement occurred year round, but varied significantly across time and space. Annual coral settlement was low (~54.72 spat m(-2) yr(-1)) relative to other equatorial regions, but there was evidence of temporal variation in settlement rates. Peak settlement occurred between March-May and September-November, coinciding with annual coral spawning periods (March-April and October), while the lowest settlement occurred from December-February during the northeast monsoon. A period of high settlement was also observed between June and August in the first year (2011/12), possibly due to some species spawning outside predicted spawning periods, larvae settling from other locations or extended larval settlement competency periods. Settlement rates varied significantly among sites, but spatial variation was relatively consistent between years, suggesting the strong effects of local coral assemblages or environmental conditions. Pocilloporidae were the most abundant coral spat (83.6%), while Poritidae comprised only 6% of the spat, and Acroporidae coral spat. These results indicate that current settlement patterns are reinforcing the local adult assemblage structure ('others'; i.e. sediment-tolerant coral taxa) in Singapore, but that the replenishment capacity of Singapore's reefs appears relatively constrained, which could lead

  2. Decay of equatorial ring current ions and associated aeronomical consequences

    Science.gov (United States)

    Fok, M.-C.; Kozyra, J. U.; Nagy, A. F.; Rasmussen, C. E.; Khazanov, G. V.

    1993-01-01

    The decay of the major ion species which constitute the ring current is studied by solving the time evolution of their distribution functions during the recovery phase of a moderate geomagnetic storm. In this work, only equatorially mirroring particles are considered. Particles are assumed to move subject to E x B and gradient drifts. They also experience loses along their drift paths. Two loss mechanisms are considered: charge exchange with neutral hydrogen atoms and Coulomb collisions with thermal plasma in the plasmasphere. Thermal plasma densities are calculated with a plasmaspheric model employing a time-dependent convection electric field model. The drift-loss model successfully reproduces a number of important and observable features in the distribution function. Charge exchange is found to be the major loss mechanism for the ring current ions; however the important effects of Coulomb collisions on both the ring current and thermal populations are also presented. The model predicts the formation of a low-energy (less than 500 eV) ion population as a result of energy degradation caused by Coulomb collision of the ring current ions with the plasmaspheric electrons; this population may be one source of the low-energy ions observed during active and quiet periods in the inner magnetosphere. The energy transferred to plasmaspheric electrons through Coulomb collisions with ring current ions is believed to be the energy source for the electron temperature enhancement and the associated 6300 A (stable auroral red (SAR) arc) emission in the subauroral region. The calculated energy deposition rate is sufficient to produce a subauroral electron temperature enhancement and SAR arc emissions that are consistent with observations of these quantities during moderate magnetic activity levels.

  3. Rosetta Ligand docking with flexible XML protocols.

    Science.gov (United States)

    Lemmon, Gordon; Meiler, Jens

    2012-01-01

    RosettaLigand is premiere software for predicting how a protein and a small molecule interact. Benchmark studies demonstrate that 70% of the top scoring RosettaLigand predicted interfaces are within 2Å RMSD from the crystal structure [1]. The latest release of Rosetta ligand software includes many new features, such as (1) docking of multiple ligands simultaneously, (2) representing ligands as fragments for greater flexibility, (3) redesign of the interface during docking, and (4) an XML script based interface that gives the user full control of the ligand docking protocol.

  4. Peptide-MHC class I stability is a stronger predictor of CTL immunogenicity than peptide affinity

    DEFF Research Database (Denmark)

    Harndahl, Mikkel Nors; Rasmussen, Michael; Nielsen, Morten

    2012-01-01

    of antigen processing and presentation in defining cytotoxic T lymphocyte (CTL) immunogenicity Assarsson et al., 2007. Using an affinity-balanced approach, we demonstrated that immunogenic peptides tend to be more stably bound to MHC-I molecules compared with non-immunogenic peptides. We also developed......Peptide-MHC class I stability is a stronger predictor of CTL immunogenicity than peptide affinity Mikkel Harndahla, Michael Rasmussena, Morten Nielsenb, Soren Buusa,∗ a Laboratory of Experimental Immunology, Faculty of Health Sciences, University of Copenhagen, Denmark b Center for Biological...... Sequence Analysis, Department of Systems Biology, Technical University of Denmark, Denmark Efficient presentation of peptide-MHC class I (pMHC-I) complexes to immune T cells should benefit from a stable peptide- MHC-I interaction. However, it has been difficult to distinguish stability from other...

  5. Bone mineral content has stronger association with lean mass than fat mass among Indian urban adolescents

    Directory of Open Access Journals (Sweden)

    Raman K Marwaha

    2015-01-01

    Full Text Available Introduction: There are conflicting reports on the relationship of lean mass (LM and fat mass (FM with bone mineral content (BMC. Given the high prevalence of Vitamin D deficiency in India, we planned the study to evaluate the relationship between LM and FM with BMC in Indian children and adolescents. The objective of the study was to evaluate the relationship of BMC with LM and FM. Materials and Methods: Total and regional BMC, LM, and FM using dual energy X-ray absorptiometry and pubertal staging were assessed in 1403 children and adolescents (boys [B]: 826; girls [G]: 577. BMC index, BMC/LM and BMC/FM ratio, were calculated. Results: The age ranged from 5 to 18 years, with a mean age of 13.2 ± 2.7 years. BMC adjusted for height (BMC index and BMC/height ratio was comparable in both genders. There was no difference in total BMC between genders in the prepubertal group but were higher in more advanced stages of pubertal maturation. The correlation of total as well as regional BMC was stronger for LM (B: Total BMC - 0.880, trunk - 0.715, leg - 0.894, arm - 0.891; G: Total BMC - 0.827, leg - 0.846, arm - 0.815 (all value indicate r2 , P < 0.0001 for all when compared with FM (B: Total BMC - 0.776, trunk - 0.676, leg - 0.772, arm - 0.728; G: Total BMC - 0.781, leg - 0.741, arm - 0.689; all P < 0.0001 except at trunk BMC (LM - 0.682 vs. FM - 0.721; all P < 0.0001, even after controlling for age, height, pubertal stage, and biochemical parameters. Conclusions: BMC had a stronger positive correlation with LM than FM.

  6. gammadelta and alphabeta T cell lineage choice: resolution by a stronger sense of being.

    Science.gov (United States)

    Wong, Gladys W; Zúñiga-Pflücker, Juan Carlos

    2010-08-01

    A common bipotent thymocyte precursor gives rise to both lineages of T cells, alphabeta and gammadelta. However, the cell intrinsic and extrinsic factors that influence alphabeta- versus gammadelta-lineage bifurcation remain controversial. gammadelta T cells play a unique and vital role in host defense, from maintaining integrity at epithelial and mucosal barriers to their newly defined role as an important innate source of interleukin-17. Although a T cell receptor (TCR)-independent fate choice may take place, emerging data supports a model in which the differential signaling capacity of alphabeta and gammadeltaTCRs play an instructional role in specifying lineage fate, with strength of signal measured by the amount of ERK/MAPK pathway activation. Here we discuss how the interplay between intrinsic TCR signals and cell extrinsic signals provided by Notch and TCR ligands help to assign and support a final lineage fate decision. 2010 Elsevier Ltd. All rights reserved.

  7. THERMODYNAMIC ASSESSMENT OF ANIONIC LIGANDS ...

    African Journals Online (AJOL)

    DJFLEX

    2010-06-30

    Jun 30, 2010 ... The presence of the ligands (ethylenediaminettraacetic acid, EDTA, enthylenediamine, en,and chloride ion, Cl-) generally improved the sorption capacity for the adsorbent, the best being. Cl- at optimum pH of 2.0 (for Co2+) and 5.0 (for Ni2+ and Cd2+). The thermodynamic studies reveal that the adsorption.

  8. No iron fertilization in the equatorial Pacific Ocean during the last ice age.

    Science.gov (United States)

    Costa, K M; McManus, J F; Anderson, R F; Ren, H; Sigman, D M; Winckler, G; Fleisher, M Q; Marcantonio, F; Ravelo, A C

    2016-01-28

    The equatorial Pacific Ocean is one of the major high-nutrient, low-chlorophyll regions in the global ocean. In such regions, the consumption of the available macro-nutrients such as nitrate and phosphate is thought to be limited in part by the low abundance of the critical micro-nutrient iron. Greater atmospheric dust deposition could have fertilized the equatorial Pacific with iron during the last ice age--the Last Glacial Period (LGP)--but the effect of increased ice-age dust fluxes on primary productivity in the equatorial Pacific remains uncertain. Here we present meridional transects of dust (derived from the (232)Th proxy), phytoplankton productivity (using opal, (231)Pa/(230)Th and excess Ba), and the degree of nitrate consumption (using foraminifera-bound δ(15)N) from six cores in the central equatorial Pacific for the Holocene (0-10,000 years ago) and the LGP (17,000-27,000 years ago). We find that, although dust deposition in the central equatorial Pacific was two to three times greater in the LGP than in the Holocene, productivity was the same or lower, and the degree of nitrate consumption was the same. These biogeochemical findings suggest that the relatively greater ice-age dust fluxes were not large enough to provide substantial iron fertilization to the central equatorial Pacific. This may have been because the absolute rate of dust deposition in the LGP (although greater than the Holocene rate) was very low. The lower productivity coupled with unchanged nitrate consumption suggests that the subsurface major nutrient concentrations were lower in the central equatorial Pacific during the LGP. As these nutrients are today dominantly sourced from the Subantarctic Zone of the Southern Ocean, we propose that the central equatorial Pacific data are consistent with more nutrient consumption in the Subantarctic Zone, possibly owing to iron fertilization as a result of higher absolute dust fluxes in this region. Thus, ice-age iron fertilization in the

  9. Crystallization of protein–ligand complexes

    International Nuclear Information System (INIS)

    Hassell, Anne M.; An, Gang; Bledsoe, Randy K.; Bynum, Jane M.; Carter, H. Luke III; Deng, Su-Jun J.; Gampe, Robert T.; Grisard, Tamara E.; Madauss, Kevin P.; Nolte, Robert T.; Rocque, Warren J.; Wang, Liping; Weaver, Kurt L.; Williams, Shawn P.; Wisely, G. Bruce; Xu, Robert; Shewchuk, Lisa M.

    2007-01-01

    Methods presented for growing protein–ligand complexes fall into the categories of co-expression of the protein with the ligands of interest, use of the ligands during protein purification, cocrystallization and soaking the ligands into existing crystals. Obtaining diffraction-quality crystals has long been a bottleneck in solving the three-dimensional structures of proteins. Often proteins may be stabilized when they are complexed with a substrate, nucleic acid, cofactor or small molecule. These ligands, on the other hand, have the potential to induce significant conformational changes to the protein and ab initio screening may be required to find a new crystal form. This paper presents an overview of strategies in the following areas for obtaining crystals of protein–ligand complexes: (i) co-expression of the protein with the ligands of interest, (ii) use of the ligands during protein purification, (iii) cocrystallization and (iv) soaks

  10. Development of ITER equatorial EC launcher for reliability improvement

    International Nuclear Information System (INIS)

    Takahashi, K.; Noriyuki, K.; Kajiwara, K.; Kasugai, A.; Sakamoto, K.

    2007-01-01

    Full text: Establishing the conceptual design of the ITER equatorial EC launcher, design studies and development of the launcher components such as a front shield, a steering mirror, a torus window and etc... were carried out. For the next stage, the practical and reliable design of the launcher is essential. In order to achieve the task, the trial fabrication of the component, such as a steering mirror, drive mechanism for the mirror and waveguide components, high power RF experiment of a dog-leg structure transmission line and the windows and so on has been carried out. The steering mirror prototype including the spiral cooling tubes was fabricated under the present design. Hot isostatic press (HIP) technique for the bonding between the Cu-alloy mirror body and the stainless steel (SS) cooling tubes inside was applied. The test of water flow was so far carried out and the expected flow rate was successfully obtained. The test of the drive mechanism for the mirror was also carried out under 100 deg. C and vacuum, the relevant ITER circumstance. It was found that the LM actuator was stuck due to the unexpected load in the link structure. Then, the link has been removed and the actuator structure has been modified. The SS corrugated waveguide prototype for the launcher that had several cooling holes along the waveguide axis was fabricated. The corrugation surface was coated by Cu so as to minimize the ohmic loss at the inner surface. The RF test with 0.7MW was carried out. The cooling water was saturated and the loss was approximately estimated as 0.34kW that corresponds to the surface heat load of 1.8kW/m 2 at 1MW transmission. It is recognized that 1MW transmission is possible in the SS/Cu waveguide. The further analytical studies of the launcher structure have also been carried out. The quasi-optical (QO) transmission layout has been considered instead of the waveguide in the present design. The advantage of this option is possibly reducing the cost. According to

  11. Reflection of equatorial Kelvin waves at eastern ocean boundaries Part I: hypothetical boundaries

    Directory of Open Access Journals (Sweden)

    J. Soares

    1999-06-01

    Full Text Available A baroclinic shallow-water model is developed to investigate the effect of the orientation of the eastern ocean boundary on the behavior of equatorial Kelvin waves. The model is formulated in a spherical polar coordinate system and includes dissipation and non-linear terms, effects which have not been previously included in analytical approaches to the problem. Both equatorial and middle latitude response are considered given the large latitudinal extent used in the model. Baroclinic equatorial Kelvin waves of intraseasonal, seasonal and annual periods are introduced into the domain as pulses of finite width. Their subsequent reflection, transmission and dissipation are investigated. It is found that dissipation is very important for the transmission of wave energy along the boundary and for reflections from the boundary. The dissipation was found to be dependent not only on the presence of the coastal Kelvin waves in the domain, but also on the period of these coastal waves. In particular the dissipation increases with wave period. It is also shown that the equatorial β-plane approximation can allow an anomalous generation of Rossby waves at higher latitudes. Nonlinearities generally have a small effect on the solutions, within the confines of this model.Key words. Oceanography: general (equatorial oceanography; numerical modeling · Oceanography: physical (eastern boundary currents

  12. Late Quaternary CaCO3 stratigraphy of the eastern equatorial Pacific

    Science.gov (United States)

    Snoeckx, Hilde; Rea, David K.

    1994-04-01

    Four patterns of CaCO3 abundance occur in cores retrieved from the eastern equatorial Pacific during the Venture 01 expedition. Core locations lie along a north-south transect at 110°W underneath the different currents of the equatorial current system and along an east-west transect from 110° to 90°W, at approximately 3°S, underneath the South Equatorial Current. The "classic" or central equatorial Pacific pattern of CaCO3 abundance maxima associated with glacial stages as defined by the δ18O record characterizes only a small portion of the area studied. In the area where the Peru current turns west to join the South Equatorial Current, the carbonate record is characterized by a broad low, centered on interglacial carbonate stage B-3 (approximately stage 5 in δ18O stratigraphy) overlying a broad mid-Brunhes maximum. Low-amplitude variations in CaCO3 percentages are superimposed on this pattern. This pattern extends westward in a long-wavelength pattern in which the B-3 carbonate low becomes decreasingly pronounced away from the equator. The fourth pattern, observed north of 10°N, is erratic and may be only local in extent.

  13. Resonant Scattering of Radiation Belt Electrons by Off-Equatorial Magnetosonic Waves

    Science.gov (United States)

    Ni, Binbin; Zou, Zhengyang; Fu, Song; Cao, Xing; Gu, Xudong; Xiang, Zheng

    2018-02-01

    Fast magnetosonic (MS) waves are commonly regarded as electromagnetic waves that are characteristically confined within ±3° of the geomagnetic equator. We report two typical off-equatorial MS events observed by Van Allen Probes, that is, the 8 May 2014 event that occurred at the geomagnetic latitudes of 7.5°-9.2° both inside and outside the plasmasphere with the wave amplitude up to 590 pT and the 9 January 2014 event that occurred at the latitudes of—(15.7°-17.5°) outside the plasmasphere with a smaller amplitude about 81 pT. Detailed test particle simulations quantify the electron resonant scattering rates by the off-equatorial MS waves to find that they can cause the pitch angle scattering and momentum diffusion of radiation belt electrons with equatorial pitch angles belt electron butterfly distributions for a broad energy range from 100 keV to >1 MeV within an hour. Our study clearly demonstrates that the presence of off-equatorial MS waves, in addition to equatorial MS waves, can contribute importantly to the dynamical variations of radiation belt electron fluxes and their pitch angle distribution.

  14. Toward controlling water oxidation catalysis: tunable activity of ruthenium complexes with axial imidazole/DMSO ligands.

    Science.gov (United States)

    Wang, Lei; Duan, Lele; Stewart, Beverly; Pu, Maoping; Liu, Jianhui; Privalov, Timofei; Sun, Licheng

    2012-11-14

    Using the combinations of imidazole and dimethyl sulfoxide (DMSO) as axial ligands and 2,2'-bipyridine-6,6'-dicarboxylate (bda) as the equatorial ligand, we have synthesized six novel ruthenium complexes with noticeably different activity as water oxidation catalysts (WOCs). In four C(s) symmetric Ru(II)(κ(3)-bda)(DMSO)L(2) complexes L = imidazole (1), N-methylimidazole (2), 5-methylimidazole (3), and 5-bromo-N-methylimidazole (4). Additionally, in two C(2v) symmetric Ru(II)(κ(4)-bda)L(2) complexes L = 5-nitroimidazole (5) and 5-bromo-N-methylimidazole (6), that is, fully equivalent axial imidazoles. A detailed characterization of all complexes and the mechanistic investigation of the catalytic water oxidation have been carried out with a number of experimental techniques, that is, kinetics, electrochemistry and high resolution mass spectrometry (HR-MS), and density functional theory (DFT) calculations. We have observed the in situ formation of a Ru(II)-complex with the accessible seventh coordination position. The measured catalytic activities and kinetics of complex 1-6 revealed details about an important structure-activity relation: the connection between the nature of axial ligands in the combination and either the increase or decrease of the catalytic activity. In particular, an axial DMSO group substantially increases the turnover frequency of WOCs reported in the article, with the ruthenium-complex having one axial 5-bromo-N-methyl-imidazole and one axial DMSO (4), we have obtained a high initial turnover frequency of ∼180 s(-1). DFT modeling of the binuclear reaction pathway of the O-O bond formation in catalytic water oxidation further corroborated the concept of the mechanistic significance of the axial ligands and rationalized the experimentally observed difference in the activity of complexes with imidazole/DMSO and imidazole/imidazole combinations of axial ligands.

  15. Marine sedimentary environments on some parts of the tropical and equatorial Atlantic margins of Africa during the Late Quaternary

    Science.gov (United States)

    Barusseau, J. P.; Giresse, P.; Faure, H.; Lezine, A. M.; Masse, J. P.

    1988-01-01

    ultrafine sands is recorded in the surficial sediments. Carbonate biogenic deposition The main sedimentary unit of bioclastic origin formed during the first standstill of the Holocene sea-level rise (12,000 y B.P.). It is a belt of Amphistegina sands, recorded on the outer shelf between 80 and 120 m, which represents a fossil fauna. Recent bioclastic sands are more developed in the tropical region, north of the area which has been studied; they are more dependent on structural rocky shoals, than in the equatorial zone where terrigenous influxes impede their development. Glauconite deposition This kind of sediment is characteristic of the equatorial regions where two major conditions were satisfied during the low-stand phase: (1) the presence of faecal pellet substrates due to the increase of primary productivity related to the stronger upwellings and, (2) larger iron input releases by podzolic soil evolution. Northward of the Congo-Gabon shelf, effectiveness of both conditions decreased. Offshore from the Coˆte d'Ivoire, iron was trapped in ferralitic profiles and on the Senegal and Mauritania shelves the green grains are rare and berthierine occurs in a limited time and space range.

  16. -Pincer Ligand Family through Ligand Post-Modification

    KAUST Repository

    Huang, Mei-Hui

    2017-10-02

    A series of air-stable nickel complexes containing triazine-based PN3P-pincer ligands were synthesized and fully characterized. Complex 3 contains a de-aromatized central triazine ring from the deprotonation of one of the N–H arms. With a post-modification strategy, the Me-PN3P*NiCl complex (3) could be converted into a new class of diimine–traizine PN3P-pincer nickel complexes.

  17. Chelating ligands for nanocrystals' surface functionalization

    NARCIS (Netherlands)

    Querner, Claudia; Reiss, Peter; Bleuse, Joël; Pron, Adam

    2004-01-01

    A new family of ligands for the surface functionalization of CdSe nanocrystals is proposed, namely alkyl or aryl derivatives of carbodithioic acids (R-C(S)SH). The main advantages of these new ligands are as follows: they nearly quantitatively exchange the initial surface ligands (TOPO) in very mild

  18. Regular Exercisers Have Stronger Pelvic Floor Muscles than Non-Regular Exercisers at Midpregnancy.

    Science.gov (United States)

    Bø, Kari; Ellstrøm Engh, Marie; Hilde, Gunvor

    2017-12-26

    Today, all healthy pregnant women are encouraged to be physically active throughout pregnancy, with recommendations to participate in at least 30 min of aerobic activity on most days of the week, in addition to perform strength training of the major muscle groups 2-3 days per week, and also pelvic floor muscle training. There is, however, an ongoing debate whether general physical activity enhances or declines pelvic floor muscle function. To compare vaginal resting pressure, pelvic floor muscle strength and endurance in regular exercisers (exercise ≥ 30 minutes ≥ 3 times per week) and non-exercisers at mid-pregnancy. Furthermore, to assess whether regular general exercise or pelvic floor muscle strength was associated with urinary incontinence. This was a cross-sectional study at mean gestational week 20.9 (± 1.4) including 218 nulliparous pregnant women, mean age 28.6 years (range 19-40) and pre-pregnancy body mass index 23.9 kg/m 2 (SD 4.0). Vaginal resting pressure, pelvic floor muscle strength and pelvic floor muscle endurance were measured by a high precision pressure transducer connected to a vaginal balloon. International Consultation on Incontinence Questionnaire Urinary Incontinence Short Form was used to assess urinary incontinence. Differences between groups were analyzed using Independent Sample T-test. Linear regression analysis was conducted to adjust for pre-pregnancy body mass index, age, smoking during pregnancy and regular pelvic floor muscle training during pregnancy. P-value was set to ≤ 0.05. Regular exercisers had statistically significant stronger ( mean 6.4 cm H 2 O (95% CI: 1.7, 11.2)) and more enduring ( mean 39.9 cm H 2 Osec (95% CI: 42.2, 75.7)) pelvic floor muscles. Only pelvic floor muscle strength remained statistically significant, when adjusting for possible confounders. Pelvic floor muscle strength and not regular general exercise was associated with urinary continence (adjusted B: -6.4 (95% CI: -11.5, -1.4)). Regular

  19. Hippocampal-Prefrontal Reactivation during Learning Is Stronger in Awake Compared with Sleep States.

    Science.gov (United States)

    Tang, Wenbo; Shin, Justin D; Frank, Loren M; Jadhav, Shantanu P

    2017-12-06

    Hippocampal sharp-wave ripple (SWR) events occur during both behavior (awake SWRs) and slow-wave sleep (sleep SWRs). Awake and sleep SWRs both contribute to spatial learning and memory, thought to be mediated by the coordinated reactivation of behavioral experiences in hippocampal-cortical circuits seen during SWRs. Current hypotheses suggest that reactivation contributes to memory consolidation processes, but whether awake and sleep reactivation are suited to play similar or different roles remains unclear. Here we addressed that issue by examining the structure of hippocampal (area CA1) and prefrontal (PFC) activity recorded across behavior and sleep stages in male rats learning a spatial alternation task. We found a striking state difference: prefrontal modulation during awake and sleep SWRs was surprisingly distinct, with differing patterns of excitation and inhibition. CA1-PFC synchronization was stronger during awake SWRs, and spatial reactivation, measured using both pairwise and ensemble measures, was more structured for awake SWRs compared with post-task sleep SWRs. Stronger awake reactivation was observed despite the absence of coordination between network oscillations, namely hippocampal SWRs and cortical delta and spindle oscillations, which is prevalent during sleep. Finally, awake CA1-PFC reactivation was enhanced most prominently during initial learning in a novel environment, suggesting a key role in early learning. Our results demonstrate significant differences in awake and sleep reactivation in the hippocampal-prefrontal network. These findings suggest that awake SWRs support accurate memory storage and memory-guided behavior, whereas sleep SWR reactivation is better suited to support integration of memories across experiences during consolidation. SIGNIFICANCE STATEMENT Hippocampal sharp-wave ripples (SWRs) occur both in the awake state during behavior and in the sleep state after behavior. Awake and sleep SWRs are associated with memory

  20. Geology of the Venus equatorial region from Pioneer Venus radar imaging

    International Nuclear Information System (INIS)

    Senske, D.A.; Head, J.W.

    1989-01-01

    The surface characteristics and morphology of the equatorial region of Venus were first described by Masursky et al. who showed this part of the planet to be characterized by two topographic provinces, rolling plains and highlands, and more recently by Schaber who described and interpreted tectonic zones in the highlands. Using Pioneer Venus (PV) radar image data (15 deg S to 45 deg N), Senske and Head examined the distribution, characteristics, and deposits of individual volcanic features in the equatorial region, and in addition classified major equatorial physiographic and tectonic units on the basis of morphology, topographic signature, and radar properties derived from the PV data. Included in this classification are: plains (undivided), inter-highland tectonic zones, tectonically segmented linear highlands, upland rises, tectonic junctions, dark halo plains, and upland plateaus. In addition to the physiographic units, features interpreted as coronae and volcanic mountains have also been mapped. The latter four of the physiographic units along with features interpreted to be coronae

  1. Typical disturbances of the daytime equatorial F region observed with a high-resolution HF radar

    Directory of Open Access Journals (Sweden)

    E. Blanc

    1998-06-01

    Full Text Available HF radar measurements were performed near the magnetic equator in Africa (Korhogo 9°24'63''N–5°37'38''W during the International Equatorial Electrojet Year (1993–1994. The HF radar is a high-resolution zenithal radar. It gives ionograms, Doppler spectra and echo parameters at several frequencies simultaneously. This paper presents a comparative study of the daytime ionospheric structures observed during 3 days selected as representative of different magnetic conditions, given by magnetometer measurements. Broad Doppler spectra, large echo width, and amplitude fluctuations revealed small-scale instability processes up to the F-region peak. The height variations measured at different altitudes showed gravity waves and larger-scale disturbances related to solar daytime influence and equatorial electric fields. The possibility of retrieving the ionospheric electric fields from these Doppler or height variation measurements in the presence of the other possible equatorial ionospheric disturbances is discussed.

  2. Equatorial Atlantic interannual variability and its relation to dynamic and thermodynamic processes

    Directory of Open Access Journals (Sweden)

    J. Jouanno

    2017-11-01

    Full Text Available The contributions of the dynamic and thermodynamic forcing to the interannual variability of the equatorial Atlantic sea surface temperature (SST are investigated using a set of interannual regional simulations of the tropical Atlantic Ocean. The ocean model is forced with an interactive atmospheric boundary layer, avoiding damping toward prescribed air temperature as is usually the case in forced ocean models. The model successfully reproduces a large fraction (R2  =  0.55 of the observed interannual variability in the equatorial Atlantic. In agreement with leading theories, our results confirm that the interannual variations of the dynamical forcing largely contributes to this variability. We show that mean and seasonal upper ocean temperature biases, commonly found in fully coupled models, strongly favor an unrealistic thermodynamic control of the equatorial Atlantic interannual variability.

  3. Centrifugal distortion of the Jovian magnetosphere by an equatorially confined current sheet

    International Nuclear Information System (INIS)

    Hill, T.W.; Carbary, J.F.

    1978-01-01

    Ions from the Galilean satellites form a thin equatorial current sheet as they diffuse outward in the Jovian magnetosphere. We present here a self-consistent quantitative model of the magnetic field perturbation produced by such ions, assuming loss-free radial transport, strong equatorial confinement, and a static balance between magnetic tension and the corotational centrifugal force. The resulting field configuration exhibits a sharp cusplike distortion near the equatorial plane, resembling qualitatively the 'magnetodisc' configuration inferred from Pioneer encounter data. The model contains one adjustable parameter that is related to the (unknown) mass injection rate at the satellite(s); the value of this parameter determines the distance at which the outward distortion becomes important. Comparison of observed and model field configurations may provide a means of estimating the rate of mass injection from the satellites

  4. Observations of equatorial ionization anomaly over Africa and Middle East during a year of deep minimum

    Directory of Open Access Journals (Sweden)

    O. Bolaji

    2017-01-01

    Full Text Available In this work, we investigated the veracity of an ion continuity equation in controlling equatorial ionization anomaly (EIA morphology using total electron content (TEC of 22 GPS receivers and three ground-based magnetometers (Magnetic Data Acquisition System, MAGDAS over Africa and the Middle East (Africa–Middle East during the quietest periods. Apart from further confirmation of the roles of equatorial electrojet (EEJ and integrated equatorial electrojet (IEEJ in determining hemispheric extent of EIA crest over higher latitudes, we found some additional roles played by thermospheric meridional neutral wind. Interestingly, the simultaneous observations of EIA crests in both hemispheres of Africa–Middle East showed different morphology compared to that reported over Asia. We also observed interesting latitudinal twin EIA crests domiciled at the low latitudes of the Northern Hemisphere. Our results further showed that weak EEJ strength associated with counter electrojet (CEJ during sunrise hours could also trigger twin EIA crests over higher latitudes.

  5. Stronger associations of obesity with prehypertension and hypertension in young women than in young men.

    Science.gov (United States)

    Wakabayashi, Ichiro

    2012-07-01

    Obesity is an important risk factor for prehypertension and hypertension, and there are sex-specific differences in prevalences of obesity and hypertension. The aim of this study was to determine whether sex influences the relationships of obesity with prehypertension and hypertension. The participants were 28,325 Japanese men and women aged 20-39 years. Obesity was evaluated by BMI (≥ 25 kg/m) and waist-to-height ratio (WHtR ≥ 0.5). Associations of obesity with prehypertension and hypertension were compared in men and women by using odds ratio (OR) and area under the curve (AUC). ORs for prehypertension and hypertension in participants with vs. participants without high BMI or WHtR were significantly higher than a reference level of 1.00 both in men and women and were significantly higher in women than in men. ORs for prehypertension and hypertension of participants with vs. participants without high BMI were 3.10 (2.84-3.38) (men) vs. 5.54 (4.80-6.40) (women) (P men) vs. 34.58 (26.55-45.04) (women) (P men. The results suggest that the associations of obesity with prehypertension and hypertension are stronger in women than in men.

  6. Stronger activation of SREBP-1a by nucleus-localized HBx

    International Nuclear Information System (INIS)

    Wu, Qi; Qiao, Ling; Yang, Jian; Zhou, Yan; Liu, Qiang

    2015-01-01

    We previously showed that hepatitis B virus (HBV) X protein activates the sterol regulatory element-binding protein-1a (SREBP-1a). Here we examined the role of nuclear localization of HBx in this process. In comparison to the wild-type and cytoplasmic HBx, nuclear HBx had stronger effects on SREBP-1a and fatty acid synthase transcription activation, intracellular lipid accumulation and cell proliferation. Furthermore, nuclear HBx could activate HBV enhancer I/X promoter and was more effective on up-regulating HBV mRNA level in the context of HBV replication than the wild-type HBx, while the cytoplasmic HBx had no effect. Our results demonstrate the functional significance of the nucleus-localized HBx in regulating host lipogenic pathway and HBV replication. - Highlights: • Nuclear HBx is more effective on activating SREBP-1a and FASN transcription. • Nuclear HBx is more effective on enhancing intracellular lipid accumulation. • Nuclear HBx is more effective on enhancing cell proliferation. • Nuclear HBx up-regulates HBV enhancer I/X promoter activity. • Nuclear HBx increases HBV mRNA level in the context of HBV replication

  7. Stronger activation of SREBP-1a by nucleus-localized HBx

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Qi [VIDO-InterVac, Veterinary Microbiology, University of Saskatchewan, Saskatoon (Canada); Qiao, Ling [VIDO-InterVac, University of Saskatchewan, Saskatoon, Saskatchewan (Canada); Yang, Jian [Drug Discovery Group, University of Saskatchewan, Saskatoon, Saskatchewan (Canada); Zhou, Yan [VIDO-InterVac, Veterinary Microbiology, Vaccinology and Immunotherapeutics, University of Saskatchewan, Saskatoon, Saskatchewan (Canada); Liu, Qiang, E-mail: qiang.liu@usask.ca [VIDO-InterVac, Veterinary Microbiology, Vaccinology and Immunotherapeutics, University of Saskatchewan, Saskatoon, Saskatchewan (Canada)

    2015-05-08

    We previously showed that hepatitis B virus (HBV) X protein activates the sterol regulatory element-binding protein-1a (SREBP-1a). Here we examined the role of nuclear localization of HBx in this process. In comparison to the wild-type and cytoplasmic HBx, nuclear HBx had stronger effects on SREBP-1a and fatty acid synthase transcription activation, intracellular lipid accumulation and cell proliferation. Furthermore, nuclear HBx could activate HBV enhancer I/X promoter and was more effective on up-regulating HBV mRNA level in the context of HBV replication than the wild-type HBx, while the cytoplasmic HBx had no effect. Our results demonstrate the functional significance of the nucleus-localized HBx in regulating host lipogenic pathway and HBV replication. - Highlights: • Nuclear HBx is more effective on activating SREBP-1a and FASN transcription. • Nuclear HBx is more effective on enhancing intracellular lipid accumulation. • Nuclear HBx is more effective on enhancing cell proliferation. • Nuclear HBx up-regulates HBV enhancer I/X promoter activity. • Nuclear HBx increases HBV mRNA level in the context of HBV replication.

  8. Length effects in pseudo-word spelling: stronger in dyslexic than in non-dyslexic students.

    Science.gov (United States)

    Juul, Holger; Petersen, Dorthe Klint

    2017-10-01

    It is often discussed whether dyslexics show a deviant pattern of reading and spelling development when compared to typically developing students, or whether they follow the same pattern as other students, only at markedly slower rate. The present cross-sectional study investigated phonological encoding skills in dyslexic Danish students. We compared dyslexic and non-dyslexic students from grades 3, 5, 7, and 9 and examined whether effects of item length were stronger in the dyslexic groups. Mixed between-within subjects analyses of variance revealed significant interactions between dyslexia status and item length as the dyslexics at all grade levels were more affected by item length than their non-dyslexic peers. A marked developmental delay was apparent as the dyslexic group from grade 9 performed on approximately the same level as the non-dyslexic group from grade 3. Although the overall difference between these two groups was not significant, a significant interaction between dyslexia status and item length remained because the grade 9 dyslexics were more affected by item length than the younger non-dyslexic students. This difference in error profiles suggests a difference in the developmental patterns of dyslexic vs. non-dyslexic students.

  9. Brain Potentials Highlight Stronger Implicit Food Memory for Taste than Health and Context Associations.

    Science.gov (United States)

    Hoogeveen, Heleen R; Jolij, Jacob; Ter Horst, Gert J; Lorist, Monicque M

    2016-01-01

    Increasingly consumption of healthy foods is advised to improve population health. Reasons people give for choosing one food over another suggest that non-sensory features like health aspects are appreciated as of lower importance than taste. However, many food choices are made in the absence of the actual perception of a food's sensory properties, and therefore highly rely on previous experiences of similar consumptions stored in memory. In this study we assessed the differential strength of food associations implicitly stored in memory, using an associative priming paradigm. Participants (N = 30) were exposed to a forced-choice picture-categorization task, in which the food or non-food target images were primed with either non-sensory or sensory related words. We observed a smaller N400 amplitude at the parietal electrodes when categorizing food as compared to non-food images. While this effect was enhanced by the presentation of a food-related word prime during food trials, the primes had no effect in the non-food trials. More specifically, we found that sensory associations are stronger implicitly represented in memory as compared to non-sensory associations. Thus, this study highlights the neuronal mechanisms underlying previous observations that sensory associations are important features of food memory, and therefore a primary motive in food choice.

  10. Phytoplankton Communities Exhibit a Stronger Response to Environmental Changes than Bacterioplankton in Three Subtropical Reservoirs.

    Science.gov (United States)

    Liu, Lemian; Yang, Jun; Lv, Hong; Yu, Xiaoqing; Wilkinson, David M; Yang, Jun

    2015-09-15

    The simultaneous analysis of multiple components of ecosystems is crucial for comprehensive studies of environmental changes in aquatic ecosystems, but such studies are rare. In this study, we analyzed simultaneously the bacterioplankton and phytoplankton communities in three Chinese subtropical reservoirs and compared the response of these two components to seasonal environmental changes. Time-lag analysis indicated that the temporal community dynamics of both bacterioplankton and phytoplankton showed significant directional changes, and variance partitioning suggested that the major reason was the gradual improvement of reservoir water quality from middle eutrophic to oligo-mesotrophic levels during the course of our study. In addition, we found a higher level of temporal stability or stochasticity in the bacterioplankton community than in the phytoplankton community. Potential explanations are that traits associated with bacteria, such as high abundance, widespread dispersal, potential for rapid growth rates, and rapid evolutionary adaptation, may underlie the different stability or stochasticity of bacterioplankton and phytoplankton communities to the environmental changes. In addition, the indirect response of bacterioplankton to nitrogen and phosphorus may result in the fact that environmental deterministic selection was stronger for the phytoplankton than for the bacterioplankton communities.

  11. Age differences in autobiographical memory across the adult lifespan: older adults report stronger phenomenology.

    Science.gov (United States)

    Luchetti, Martina; Sutin, Angelina R

    2018-01-01

    As an individual's life story evolves across adulthood, the subjective experience (phenomenology) of autobiographical memory likely changes. In addition to age at retrieval, both the recency of the memory and the age when a memory is formed may be particularly important to its phenomenology. The present work examines the effect of three temporal factors on phenomenology ratings: (a) age of the participant, (b) age at the event reported in the memory, and (c) memory age (recency). A large sample of Americans (N = 1120), stratified by chronological age, recalled and rated two meaningful memories, a Turning Point and an Early Childhood Memory. Ratings of phenomenology (e.g., vividness of turning points) were higher among older adults compared to younger adults. Memories of events from the reminiscence bump were more positive in valence than events from other time periods but did not differ on other phenomenological dimensions; recent memories had stronger phenomenology than remote memories. In contrast to phenomenology, narrative content was generally unrelated to participant age, age at the event, or memory age. Overall, the findings indicate age-related differences in how meaningful memories are re-experienced.

  12. Speed versus endurance tradeoff in plants: Leaves with higher photosynthetic rates show stronger seasonal declines.

    Science.gov (United States)

    Zhang, Yong-Jiang; Sack, Lawren; Cao, Kun-Fang; Wei, Xue-Mei; Li, Nan

    2017-02-10

    We tested for a tradeoff across species between plant maximum photosynthetic rate and the ability to maintain photosynthesis under adverse conditions in the unfavorable season. Such a trade-off would be consistent with the observed trade-off between maximum speed and endurance in athletes and some animals that has been explained by cost-benefit theory. This trend would have importance for the general understanding of leaf design, and would simplify models of annual leaf carbon relations. We tested for such a trade-off using a database analysis across vascular plants and using an experimental approach for 29 cycad species, representing an ancient plant lineage with diversified evergreen leaves. In both tests, a higher photosynthetic rate per mass or per area in the favorable season was associated with a stronger absolute or percent decline in the unfavorable season. We resolved a possible mechanism based on biomechanics and nitrogen allocation; cycads with high leaf toughness (leaf mass per area) and higher investment in leaf construction than in physiological function (C/N ratio) tended to have lower warm season photosynthesis but less depression in the cool season. We propose that this trade-off, consistent with cost-benefit theory, represents a significant physio-phenological constraint on the diversity and seasonal dynamics of photosynthetic rate.

  13. A stronger necessary condition for the multistationarity of chemical reaction networks.

    Science.gov (United States)

    Soliman, Sylvain

    2013-11-01

    Biochemical reaction networks grow bigger and bigger, fed by the high-throughput data provided by biologists and bred in open repositories of models allowing merging and evolution. Nevertheless, since the available data is still very far from permitting the identification of the increasing number of kinetic parameters of such models, the necessity of structural analyses for describing the dynamics of chemical networks appears stronger every day. Using the structural information, notably from the stoichiometric matrix, of a biochemical reaction system, we state a more strict version of the famous Thomas' necessary condition for multistationarity. In particular, the obvious cases where Thomas' condition was trivially satisfied, mutual inhibition due to a multimolecular reaction and mutual activation due to a reversible reaction, can now easily be ruled out. This more strict condition shall not be seen as some version of Thomas' circuit functionality for the continuous case but rather as related and complementary to the whole domain of the structural analysis of (bio)chemical reaction systems, as pioneered by the chemical reaction network theory.

  14. Plant Identity Exerts Stronger Effect than Fertilization on Soil Arbuscular Mycorrhizal Fungi in a Sown Pasture.

    Science.gov (United States)

    Zheng, Yong; Chen, Liang; Luo, Cai-Yun; Zhang, Zhen-Hua; Wang, Shi-Ping; Guo, Liang-Dong

    2016-10-01

    Arbuscular mycorrhizal (AM) fungi play key roles in plant nutrition and plant productivity. AM fungal responses to either plant identity or fertilization have been investigated. However, the interactive effects of different plant species and fertilizer types on these symbiotic fungi remain poorly understood. We evaluated the effects of the factorial combinations of plant identity (grasses Avena sativa and Elymus nutans and legume Vicia sativa) and fertilization (urea and sheep manure) on AM fungi following 2-year monocultures in a sown pasture field study. AM fungal extraradical hyphal density was significantly higher in E. nutans than that in A. sativa and V. sativa in the unfertilized control and was significantly increased by urea and manure in A. sativa and by manure only in E. nutans, but not by either fertilizers in V. sativa. AM fungal spore density was not significantly affected by plant identity or fertilization. Forty-eight operational taxonomic units (OTUs) of AM fungi were obtained through 454 pyrosequencing of 18S rDNA. The OTU richness and Shannon diversity index of AM fungi were significantly higher in E. nutans than those in V. sativa and/or A. sativa, but not significantly affected by any fertilizer in all of the three plant species. AM fungal community composition was significantly structured directly by plant identity only and indirectly by both urea addition and plant identity through soil total nitrogen content. Our findings highlight that plant identity has stronger influence than fertilization on belowground AM fungal community in this converted pastureland from an alpine meadow.

  15. Harmful drinking after job loss: a stronger association during the post-2008 economic crisis?

    Science.gov (United States)

    de Goeij, Moniek C M; Bruggink, Jan-Willem; Otten, Ferdy; Kunst, Anton E

    2017-06-01

    This study investigated, among the Dutch working population, whether job loss during the post-2008 economic crisis is associated with harmful drinking and whether this association is stronger than before the crisis. Repeated cross-sectional data from the Dutch Health Interview Survey 2004-2013 were used to define episodic drinking (≥6 glasses on 1 day ≥1/week) and chronic drinking (≥14 glasses/week for women and ≥21 for men). These data were linked to longitudinal data from tax registries, to measure the experience and duration of job loss during a 5-year working history. Before the crisis, job loss experience and duration were not associated with harmful drinking. During the crisis, job loss for more than 6 months was associated with episodic drinking [OR 1.40 (95% CI 1.01; 1.94)], while current job loss was associated with chronic drinking [OR 1.43 (95% CI 1.03; 1.98)]. These associations were most clear in men and different between the pre-crisis and crisis period (p interaction = 0.023 and 0.035, respectively). The results suggest that economic crises strengthen the potential impact of job loss on harmful drinking, predominately among men.

  16. Alternative Affinity Ligands for Immunoglobulins.

    Science.gov (United States)

    Kruljec, Nika; Bratkovič, Tomaž

    2017-08-16

    The demand for recombinant therapeutic antibodies and Fc-fusion proteins is expected to increase in the years to come. Hence, extensive efforts are concentrated on improving the downstream processing. In particular, the development of better-affinity chromatography matrices, supporting robust time- and cost-effective antibody purification, is warranted. With the advances in molecular design and high-throughput screening approaches from chemical and biological combinatorial libraries, novel affinity ligands representing alternatives to bacterial immunoglobulin (Ig)-binding proteins have entered the scene. Here, we review the design, development, and properties of diverse classes of alternative antibody-binding ligands, ranging from engineered versions of Ig-binding proteins, to artificial binding proteins, peptides, aptamers, and synthetic small-molecular-weight compounds. We also provide examples of applications for the novel affinity matrices in chromatography and beyond.

  17. Ligand binding by PDZ domains

    DEFF Research Database (Denmark)

    Chi, Celestine N.; Bach, Anders; Strømgaard, Kristian

    2012-01-01

    The postsynaptic density protein-95/disks large/zonula occludens-1 (PDZ) protein domain family is one of the most common protein-protein interaction modules in mammalian cells, with paralogs present in several hundred human proteins. PDZ domains are found in most cell types, but neuronal proteins...... as pathological conditions have been reviewed recently. In this review, we focus on the molecular details of how PDZ domains bind their protein ligands and their potential as drug targets in this context....

  18. Bitopic Ligands and Metastable Binding Sites

    DEFF Research Database (Denmark)

    Fronik, Philipp; Gaiser, Birgit I; Sejer Pedersen, Daniel

    2017-01-01

    of orthosteric binding sites. Bitopic ligands have been employed to address the selectivity problem by combining (linking) an orthosteric ligand with an allosteric modulator, theoretically leading to high-affinity subtype selective ligands. However, it remains a challenge to identify suitable allosteric binding...... that have been reported to date, this type of bitopic ligands would be composed of two identical pharmacophores. Herein, we outline the concept of bitopic ligands, review metastable binding sites, and discuss their potential as a new source of allosteric binding sites....

  19. Multifractal analysis of vertical total electron content (VTEC at equatorial region and low latitude, during low solar activity

    Directory of Open Access Journals (Sweden)

    M. J. A. Bolzan

    2013-01-01

    Full Text Available This paper analyses the multifractal aspects of the GPS data (measured during a period of low solar activity obtained from two Brazilian stations: Belém (01.3° S, 48.3° W and São José dos Campos (SJC (23.2° S, 45.9° W. The results show that the respective geographic sites show important scaling differences as well as similarities when their multifractal signatures for vertical total electron content (VTEC are compared. The f(α spectra have a narrow shape for great scales, which indicates the predominance of deterministic phenomena, such as solar rotation (27 days over intermittent phenomena. Furthermore, the f(α spectra for both sites have a strong multifractality degree at small scales. This strong multifractality degree observed at small scales (1 to 12 h at both sites is because the ionosphere over Brazil is a non-equilibrium system. The differences found were that Belém presented a stronger multifractality at small scales (1 h to 12 h compared with SJC, particularly in 2006. The reason for this behaviour may be associated with the location of Belém, near the geomagnetic equator, where at this location the actions of X-rays, ultraviolet, and another wavelength from the Sun are more direct, strong, and constant throughout the whole year. Although the SJC site is near ionospheric equatorial anomaly (IEA peaks, this interpretation could explain the higher values found for the intermittent parameter μ for Belém compared with SJC. Belém also showed the presence of one or two flattening regions for f(α spectra at the same scales mentioned before. These differences and similarities also were interpreted in terms of the IEA content, where this phenomenon is an important source of intermittence due the presence of the VTEC peaks at ±20° geomagnetic latitudes.

  20. Kelvin waves near the equatorial stratopause as seen in SBUV ozone data

    Science.gov (United States)

    Hirota, Isamu; Shiotani, Masato; Sakurai, Takahiro; Gille, John C.

    1991-01-01

    Data on ozone mixing ratios derived for the time period 1979-1986 from measurements of the solar backscatter UV instrument on board Nimbus-7 were used to investigate space-time variations of atmospheric ozone in the equatorial middle atmospohere during this period. Evidence is presented for the appearance of equatorially trapped 'ozone Kelvin waves' above the 10-mb level, having a zonal wavenumber-one component and an eastward migration period of about 7 days. It is shown that Kelvin wave amplitudes are closely related to the semiannual oscillation of the zonal mean wind around the stratopause level.

  1. Radioiodinated ligands for dopamine receptors

    International Nuclear Information System (INIS)

    Kung, H.F.

    1994-01-01

    The dopamine receptor system is important for normal brain function; it is also the apparent action site for various neuroleptic drugs for the treatment of schizophrenia and other metal disorders. In the past few years radioiodinated ligands for single photon emission tomography (SPECT) have been successfully developed and tested in humans: [ 123 I]TISCH for D1 dopamine receptors; [ 123 I]IBZM, epidepride, IBF and FIDA2, four iodobenzamide derivatives, for D2/D3 dopamine receptors. In addition, [ 123 I]β-CIT (RTI-55) and IPT, cocaine derivatives, for the dopamine reuptake site are potentially useful for diagnosis of loss of dopamine neurons. The first iodinated ligand, (R)trans-7-OH-PIPAT, for D3 dopamine receptors, was synthesized and characterized with cloned cell lines (Spodoptera frugiperda, Sf9) expressing the D2 and D3 dopamine receptors and with rat basal forebrain membrane preparations. Most of the known iodobenzamides displayed similar potency in binding to both D2 and D3 dopamine receptors expressed in the cell lines. Initial studies appear to suggest that by fine tuning the structures it may be possible to develop agents specific for D2 and D3 dopamine receptors. It is important to investigate D2/D3 selectivity for this series of potent ligands

  2. Tumor targeting via integrin ligands

    Directory of Open Access Journals (Sweden)

    Udaya Kiran eMarelli

    2013-08-01

    Full Text Available Selective and targeted delivery of drugs to tumors is a major challenge for an effective cancer therapy and also to overcome the side effects associated with current treatments. Overexpression of various receptors on tumor cells is a characteristic structural and biochemical aspect of tumors and distinguishes them from physiologically normal cells. This abnormal feature is therefore suitable for selectively directing anticancer molecules to tumors by using ligands that can preferentially recognize such receptors. Several subtypes of integrin receptors that are crucial for cell adhesion, cell signaling, cell viability and motility have been shown to have an upregulated expression on cancer cells. Thus, ligands that recognize specific integrin subtypes represent excellent candidates to be conjugated to drugs or drug carrier systems and be targeted to tumors. In this regard, integrins recognizing the RGD cell adhesive sequence have been extensively targeted for tumor specific drug delivery. Here we review key recent examples on the presentation of RGD-based integrin ligands by means of distinct drug delivery systems, and discuss the prospects of such therapies to specifically target tumor cells.

  3. Occurrence of Equatorial F Region Irregularities: Evidence for Tropospheric Seeding

    Science.gov (United States)

    McClure, J. P.; Singh, S.; Bamgboye, D. K.; Johnson, F. S.; Kil, Hyosub

    1998-01-01

    We present a new gap-free version of the seasonal and longitudinal 0 (s/l) variations of P(sub EFI), the equatorial F region irregularity (EFI) occurrence probability, based on data from the AE-E spacecraft. The agreement of this and three earlier partial P(sub EFI) patterns verifies all four. We reinterpret another earlier gap-ridden pattern, that of D(bar)(sub RSF), a topside ionogram index of average darkening by range spread F. We compare it with P(sub EFI) and, using ionosonde radio science considerations, we conclude that D(bar)(sub RSF) = P(sub EFI) times a factor depending on the average number of topside plasma bubbles visible to the ionosonde. The s/l variations of D(baar)(sub RSF) thus imply s/l variations in the average spacing of bubbles, whose seeds have an occurrence probability pattern P(sub seed). For discussion we assume P(sub EFI) = P(sub inst)P(sub seed) is the pattern of F region instability. The P(sub EFI) pattern, which is by definition independent of seed and/or bubble spacing, is far too complex to be explained by the dominant paradigm, that of changes in P(sub inst) by simple changes in the F region altitude and/or north-south asymmetry. We examine evidence behind this dominance, and find it unconvincing. Both the asymmetry and sunset-node/altitude hypotheses of 1984 and 1985, respectively, seem to be partly based on misunderstood data, and their features appear displaced in time and space from those of our repeatable P(sub EFI) pattern. In contrast, if P(sub seed) variations influence the P(sub EFI) pattern and depend on thermospheric gravity waves from tropospheric convection near the dip equator, then the seasonal maxima (minima) Of P(sub EFI) could be explained, since they all occur above relatively warm (cold) surface features, where convection is maximal (minimal). Also, the hypothesis of the dominance of the P(sub seed) term could explain an unusual December/January P(sub EFI) maximum in the deep, wide, normal Pacific minimum in the

  4. Test Geochemistry of Neogloboquadrina dutertrei Reveals a Deglacial Shoaling of the Deep Chlorophyll Maximum in the Eastern Equatorial Pacific

    Science.gov (United States)

    Mekik, F.

    2017-12-01

    Mg/Ca ratios from tests of Neogloboquadrina dutertrei in two cores in the eastern equatorial Pacific (EEP) spanning the last 25,000 years reveal a peak during the deglaciation which corresponds to a drop in sea surface temperatures as observed from alkenones in previously published work. This discrepancy may be explained in part by N. dutertrei recording summer and alkenones recording winter temperatures. Previously published 230Th normalized organic flux data suggest that the EEP was a region of increased surface ocean productivity, stronger upwelling, and shallower deep chlorophyll maxima (DCM) during the deglaciation. N. dutertrei test stable isotope geochemistry from core tops in the EEP reveals a variable habitat depth for this species between 30 and 125 m water depth, and that this species does not prefer a specific temperature, but rather varies its habitat depth based on the depth of the DCM and current patterns in the EEP. We calculated δ18Osw down core using the low light temperature- δ18O equation from Bemis et al. (1988), temperature estimates from both alkenones and Mg/Ca, and δ18Ocalcite from previously published stable isotope data from N. dutertrei. Our δ18Osw estimates reveal a drop from the deglaciation to the modern of 0.8 ‰ regardless of whether alkenone or Mg/Ca based temperatures are used in the calculations. However there is an offset of about 0.5 to 2 ‰between the δ18Osw estimates made with alkenones vs Mg/Ca-based temperatures. These findings suggest that the discrepancy between alkenone and Mg/Ca based temperatures is probably related to a different current regime in the region, the shoaling of the DCM, and the shoaling of the habitat depth of N. dutertrei in the EEP due to stronger upwelling and greater surface ocean productivity during the deglaciation. We also calculated bioturbation depths down core based on 230Th normalized organic carbon fluxes which reveal deeper mixing during the deglaciation. This suggests that the peak

  5. Influence of physical and biological processes on the seasonal cycle of biogenic flux in the equatorial Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Vidya, P.J.; PrasannaKumar, S.; Gauns, M.; Verenkar, A; Unger, D.; Ramaswamy, V.

    Seasonal cycle of biogenic fluxes obtained from sediment trap at two locations 5°24` N, 86°46` E (southern Bay of Bengal trap; SBBT) and 3°34` N, 77°46` E (equatorial Indian Ocean trap; EIOT) within the equatorial Indian Ocean (EIO) were examined...

  6. Perceived stress and biological risk: is the link stronger in Russians than in Taiwanese and Americans?

    Science.gov (United States)

    Glei, Dana A; Goldman, Noreen; Shkolnikov, Vladimir M; Jdanov, Dmitri; Shkolnikova, Maria; Vaupel, James W; Weinstein, Maxine

    2013-07-01

    Allostatic load theory implies a relationship between exposure to psychological stress and multi-system physiological dysregulation. We used data from population-based samples of men and women in Russia (Moscow; n = 1800; age, mean 68.6 years), Taiwan (n = 1036; 65.6 years) and the United States (US; n = 1054; 58.0 years) -- which are likely to vary widely with respect to levels of stress exposure and biological markers -- to determine the magnitude of the association between perceived stress and physiological dysregulation. The measure of overall dysregulation was based on 15 markers including standard cardiovascular/metabolic risk factors as well as markers of inflammation and neuroendocrine activity. Subjective psychological stress was measured by the perceived stress scale. Only the Moscow sample demonstrated a positive association with overall dysregulation in both sexes. In the US, we found an association among women but not men. Among the Taiwanese, who report the lowest perceived stress, there was no association in women but an unexpected inverse relationship in men. The effects also varied across system-level subscores: the association with perceived stress was most consistent for standard cardiovascular/metabolic factors. Perceived stress was associated with inflammation and neuroendocrine activity in some samples. Although the evidence that perceived stress is the primary source of physiological dysregulation is generally modest, it was stronger in Russia where the level of perceived stress was particularly high. For Russia only, we had information about heart function based on a 24 h ambulatory electrocardiogram; perceived stress was consistently associated with heart rate dysregulation in Russian men and women.

  7. Stronger tests of mechanisms underlying geographic gradients of biodiversity: insights from the dimensionality of biodiversity.

    Directory of Open Access Journals (Sweden)

    Richard D Stevens

    Full Text Available Inference involving diversity gradients typically is gathered by mechanistic tests involving single dimensions of biodiversity such as species richness. Nonetheless, because traits such as geographic range size, trophic status or phenotypic characteristics are tied to a particular species, mechanistic effects driving broad diversity patterns should manifest across numerous dimensions of biodiversity. We develop an approach of stronger inference based on numerous dimensions of biodiversity and apply it to evaluate one such putative mechanism: the mid-domain effect (MDE. Species composition of 10,000-km(2 grid cells was determined by overlaying geographic range maps of 133 noctilionoid bat taxa. We determined empirical diversity gradients in the Neotropics by calculating species richness and three indices each of phylogenetic, functional and phenetic diversity for each grid cell. We also created 1,000 simulated gradients of each examined metric of biodiversity based on a MDE model to estimate patterns expected if species distributions were randomly placed within the Neotropics. For each simulation run, we regressed the observed gradient onto the MDE-expected gradient. If a MDE drives empirical gradients, then coefficients of determination from such an analysis should be high, the intercept no different from zero and the slope no different than unity. Species richness gradients predicted by the MDE fit empirical patterns. The MDE produced strong spatially structured gradients of taxonomic, phylogenetic, functional and phenetic diversity. Nonetheless, expected values generated from the MDE for most dimensions of biodiversity exhibited poor fit to most empirical patterns. The MDE cannot account for most empirical patterns of biodiversity. Fuller understanding of latitudinal gradients will come from simultaneous examination of relative effects of random, environmental and historical mechanisms to better understand distribution and abundance of the

  8. BUILDING STRONGER STATE ENERGY PARTNERSHIPS WITH THE U.S. DEPARTMENT OF ENERGY

    Energy Technology Data Exchange (ETDEWEB)

    Kate Burke

    2003-09-01

    This technical progress report includes an update of the progress during the third year of cooperative agreement DE-FC26-00NT40802, Building Stronger State Energy Partnerships with the U.S. Department of Energy. The report also describes the barriers in conduct of the effort, and our assessment of future progress and activities. The approach of the project included three tasks during year three. First, NASEO and its Buildings Committee were to focus on raising awareness and coordination of Rebuild activities. Through education, one-on-one communications, and presentations at NASEO meetings and other events, staff and the committee will assist Rebuild officials in stimulating interest in the program and building greater support among State Energy Office Directors. The most recent subtasks added to the project, though not directly related to Rebuild America, fall under this initial task, and support: (a) state plans to implement integrated energy and environmental initiatives, including distributed generation technologies, and (b) initiation of a state collaborative on advanced turbines and hybrid systems. The advanced turbine piece was completed during this year. During the year, a new workplan was accepted by Rebuild America's Dan Sze to supplement the work in this task. This workplan is outlined below. Second, NASEO would work to improve the efficiency of America's schools by assisting states and DOE in promoting projects that result in more energy efficient and clean energy schools and a better learning environment. This task was fully completed during this year. The third task involves energy security issues which NASEO addressed by way of a Summer Fuels Outlook Conference held Tuesday, April 8, 2003. The purpose of this educational event was to inform state, federal, local, and other energy officials about the most recent transportation fuels data and trends. The public benefits part of this task was not funded for Year 3, thus no activity occurred.

  9. Association Between Self-Esteem and Depressive Symptoms Is Stronger Among Black than White Older Adults.

    Science.gov (United States)

    Assari, Shervin

    2017-08-01

    Although poor self-esteem is a core component of depression, we still do not know if racial and ethnic groups differ in the magnitude of this link. This study compared Black and White older adults on the association between self-esteem and depressive symptoms. With a cross-sectional design, this study enrolled 1493 older individuals (age 66 or more) from the 2001 Religion, Aging, and Health Survey, a nationally representative study in the United States. Participants were either Blacks (n = 734) or Whites (n = 759). Depressive symptoms and self-esteem were measured using brief measures of the Center for Epidemiological Studies-Depression scale (CES-D) and the Rosenberg Self-Esteem Scale, respectively. Demographics, socioeconomics, and self-rated health (SRH) were covariates and self-identified race was the moderator. Linear regression models were used for data analysis. Low self-esteem was associated with more depressive symptoms (B = 0.17, 95 % CI 0.15-0.28), above and beyond all covariates. We found a significant and positive interaction between race (Black) and poor self-esteem on depressive symptoms (B = 0.34, 95 % CI 0.17-0.36), suggesting a stronger association between self-esteem and depressive symptoms among Blacks compared to Whites. Although low self-esteem is associated with higher depressive symptoms in both Whites and Blacks (p self-esteem and high depressive symptoms are more closely associated among Blacks than Whites. It is not clear whether depression leaves a larger scar on self-esteem for Blacks, or Blacks are more vulnerable to the effect of low self-esteem on depression.

  10. Synthesis of a Bis(thiophenolate)pyridine Ligand and Its Titanium, Zirconium, and Tantalum Complexes

    KAUST Repository

    Lenton, Taylor N.

    2012-11-12

    A precursor to a new tridentate LX 2 type ligand, bis(thiophenol)pyridine ((SNS)H 2 = (2-C 6H 4SH) 2-2,6-C 5H 3N), was prepared. Bis(thiophenolate)pyridine complexes of Ti, Zr, and Ta having dialkylamido coligands were synthesized and structurally characterized. The zirconium complex (SNS)Zr(NMe 2) 2 (4) displays C 2 symmetry in the solid state, unlike a related bis(phenolate)pyridine compound, C s-symmetric (ONO)Ti(NMe 2) 2. This change is likely the result of strain about the sulfur atom in the six-membered chelate with longer metal-sulfur and carbon-sulfur bonds. Solid-state structures of tantalum complexes (SNS)Ta(NMe 2) 3 (5) and (SNS)TaCl(NEt 2) 2 (6) also display pronounced C 2 twisting of the SNS ligand. 1D and 2D NMR experiments show that 5 is fluxional, with rotation about the Ta-N(amide) bonds occurring on the NMR time scale that interchange the equatorial amide methyl groups (ΔG ‡ 393 = 25.0(3) kcal/mol). The fluxional behavior of 6 in solution was also studied by variable-temperature 1H NMR. Observation of separate signals for the diastereotopic protons of the methylene unit of the diethylamide indicates that the complex remains locked on the NMR time scale in one diastereomeric conformation at temperatures below -50 °C, fast rotation about the equatorial amide Ta-N bonds occurs at higher temperature (ΔG ‡ 393 = 13.4(3) kcal/mol), and exchange of diastereomeric methylene protons occurs via inversion at Ta that interconverts antipodes (ΔG ‡ 393 ≈ 14(1) kcal/mol). © 2012 American Chemical Society.

  11. Ionic strength-dependent changes in tentacular ion exchangers with variable ligand density. I. Structural properties

    Science.gov (United States)

    Bhambure, Rahul; Gillespie, Christopher M.; Phillips, Michael; Graalfs, Heiner; Lenhoff, Abraham M.

    2016-01-01

    The ligand density critically affects the performance of ion-exchange resins in such measures as the adsorption capacity and transport characteristics. However, for tentacular and other polymer-modified exchangers, the mechanistic basis of the effect of ligand density on performance is not yet fully understood. In this study we map the ionic strength-dependent structural changes in tentacular cation exchangers with variable ligand densities as the basis for subsequent investigation of effects on functional properties. Inverse size-exclusion chromatography (ISEC), scanning electron microscopy (SEM) and small-angle x-ray scattering (SAXS) were used to assess the effect of ionic strength on the pore size and intraparticle architecture of resin variants with different ligand densities. Comparison of ISEC and cryo-SEM results shows a considerable reduction in average pore size with increasing ligand density; these methods also confirm an increase of average pore size at higher ionic strengths. SAXS analysis of ionic strength-dependent conformational changes in the grafted polyelectrolyte layer shows a characteristic ionomer peak at values of the scattering vector q (0.1 < q < 0.2 Å−1) that depend on the ligand density and the ionic strength of the solution. This peak attribution reflects nanoscale changes in the structure of the grafted polyelectrolyte chains that can in turn be responsible for observed pore-size changes in the tentacular resins. Finally, salt breakthrough experiments confirm a stronger Donnan exclusion effect on pore accessibility for small ions in the high ligand density variant. PMID:27544749

  12. Post sunset equatorial spread-F at Kwajalein and interplanetary magnetic field

    Science.gov (United States)

    Rastogi, R. G.; Chandra, H.; Janardhan, P.; Reinisch, B. W.; Bisoi, Susanta Kumar

    2017-10-01

    We connect the time sequence of changes in the IMF-Bz to the development of spread-F at an equatorial station Kwajalein on three different nights in November 2004, one during a geomagnetic quiet period and other two during geomagnetic disturbed periods. The chosen days show clear and smooth variations of IMF-Bz without any large fluctuations thereby enabling one to correlate changes in equatorial spread-F with corresponding changes in IMF-Bz. It is shown that a slow and continuous increase in the IMF-Bz over a duration of few hours has a similar effect on the equatorial ionosphere as of a sudden northward turning of the IMF-Bz in causing an electric field through the polar region and then to the equator. We conclude that the Spread-F at equatorial and low latitudes are due to echoes from ionization irregularities that arise due to the plasma instabilities generated by an eastward electric field on the large plasma density gradient in or below the base of the F-layer during any period of the night time along with the gravity driven Rayleigh-Taylor instability.

  13. Geomagnetic daily variations in H at Alcantara and Eusebio in the Brazilian equatorial region

    Energy Technology Data Exchange (ETDEWEB)

    Trivedi, N.B.; Kane, R.P.; Padilha, A.L.; Costa, J.M. da

    1989-03-01

    Daily variations in H at Alcantara (dip + 3.8) and Eusebio (dip -6.5), two stations in the equatorial electrojet region in Brazil, are compared. The electrojet in NE Brazil exhibits N-S asymmetry. The discrepancy between the daily variation range in H indicates the presence of complicated ionospheric currents in this region and warrants a detailed investigation. (author).

  14. Effect of solar flare on the equatorial electrojet in eastern Brazil region

    Indian Academy of Sciences (India)

    The effect of solar flare, sudden commencement of magnetic storm and of the disturbances ring current on the equatorial electrojet in the Eastern Brazil region, where the ground magnetic declination is as large as 20∘W is studied based on geomagnetic data with one minute resolution from Bacabal during ...

  15. Equatorial nighttime vertical f-region plasma drifts during disturbed-time in the african sector

    Science.gov (United States)

    Oyekola, O. S.; Ojo, A.; Akinrimisi, J.

    The terrestrial ionosphere deals with the basic structure and variability of plasma within the upper atmosphere of the Earth Furthermore the ionosphere comprises less than one percent of the mass of the upper atmosphere yet it has a significant influence on advanced communication and navigation systems both have important economic consequences As society beings to rely on more complex technologies those systems become more susceptible to environmental effects However there is still considerable difficulty in the understanding of the equatorial ionospheric phenomena under different solar and geomagnetic conditions despite all extensive studies in the middle and high latitudes and in equatorial and low latitude American and Indian sectors By contrast there is a remarkably sparse database at equatorial African continent of the globe Consequently we infer F-region vertical plasma drifts at the magnetic equatorial station Ibadan 7 4 o N 3 9 o E 6 o S dip from the time variation of the hourly recorded ionosonde virtual height of F layer h F data obtained during 1957-58 International Geophysical Year IGY period corresponding to a year of high solar flux under geomagnetic disturbed night hours 1800-0600 LT The results show a strong geomagnetic control of ionospheric plasma drifts velocities variability in month-to-month and at three different seasonal conditions The largest random fluctuations are observed in June solstice months The evening and morning reversal times are highly variable The average magnitude of the downward

  16. Ionospheric electron content within the equatorial F2 layer anomaly belt

    International Nuclear Information System (INIS)

    Rastogi, R.G.; Klobuchar, J.A.

    1990-01-01

    This paper describes some new results on the day-to-day behavior of the location of the equatorial anomaly in the columnar electron content. The measurements were made from a unique network of stations covering dip latitudes from 0 degree N to 25 degree N during the period in 1975-1976 near sunspot minimum when the ATS 67 satellite was visible from India. The latitudinal distribution of the total electron content on a particular day was found to depend only on the strength of the electrojet current, as determined by the difference of the horizontal magnetic field at stations on the magnetic equator and another outside the equatorial electrojet, rather than on the horizontal magnetic field measured only at the equatorial station. During magnetically disturbed periods the presence or absence of the anomaly was also found to depend only upon the strength of the electrojet current. The varying electrojet current, that is, the equatorial electric field, is very effective in moving the ionization to the anomaly latitudes of 15 degree-20 degree, but the columnar electron content over the magnetic equator remains relatively constant

  17. Hydrodynamic properties of some pelagic Crustacea from the North-Equatorial gulfstream

    NARCIS (Netherlands)

    Spaargaren, D.H.

    1980-01-01

    Measurements on underwater weight, weight in air and terminal sinking rate were collected using 8 different species of pelagic Crustacea from the North-Equatorial Gulfstream. From these data (1) animal density, (2) shape constant, determining frictional resistance at terminal sinking velocity and

  18. A study of Sq(H) variations over equatorial electrojet regions | Okeke ...

    African Journals Online (AJOL)

    The newly established geomagnetic field observations in Japan, have enabled us to analyse the 1998 data of Huancayo, Kiritimati (Christmas Island) and Pohnpei where the geomagnetic Sq(H) variations of equatorial electrojet have been studied. The diurnal variation of the monthly means of Sq(H) on the five international ...

  19. Some results of analysis of inverted echo-sounder records from the Atlantic Equatorial region

    Directory of Open Access Journals (Sweden)

    Alberto dos Santos Franco

    1985-01-01

    Full Text Available The tidal analysis of data from the Equatorial region, given by inverted echo-sounders, show considerable residuals in the frequency band of approximately 2 cycles per day. In the even harmonics of 4 and 6 cycles per day, tidal components statistically not negligible are also identified. Spectral analysis of temperature series from the same area show, on the other hand, variabilities in the same frequency bands, which suggests the occurrence of internal waves with energy distributed in these frequency bands, in the Atlantic Equatorial area.Análises de dados de maré, da zona equatorial, obtidos com ecobatímetros invertidos, mostram consideráveis resíduos na faixa de freqüências com aproximadamente dois ciclos por dia. Nos harmônicos pares com 4 e 6 ciclos por dia são também identificadas componentes de maré estatisticamente não desprezíveis. Análises espectrais de séries de temperatura obtidas na mesma área mostram, 218 por outro lado, variabilidades na mesma faixa de freqüências, o que sugere a ocorrência, na área equatorial Atlântica, de ondas internas com energia distribuída nessas faixas espectrais.

  20. Solar flux variation of the electron temperature morning overshoot in the equatorial F region

    DEFF Research Database (Denmark)

    Stolle, Claudia; Liu, H.; Truhlik, V.

    2011-01-01

    Using 8 years of CHAMP satellite observations of the equatorial electron temperature, T-e, we investigate its behavior during the morning overshoot and at ionospheric altitudes below 450 km including its variation with solar activity. The morning T-e has a maximum at the dip equator and decreases...

  1. Surface temperature of the equatorial Pacific Ocean and the Indian rainfall

    Digital Repository Service at National Institute of Oceanography (India)

    Gopinathan, C.K.

    The time variation of the monthly mean surface temperature of the equatorial Pacific Ocean during 1982-1987 has been studied in relation to summer monsoon rainfall over India The ENSO events of 1982 and 1987 were related to a significant reduction...

  2. Estimation of eddy diffusivity coefficient of heat in the upper layers of equatorial Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Zavialov, P.O.; Murty, V.S.N.

    in the Central Equatorial Arabian Sea (CEAS). A comparison of the model computed K sub(h) values with those estimated from the heat balance of the upper layer (50 m) of the sea shows good agreement in the region of weak winds (CEAS) or low turbulent mixing regime...

  3. The Effect of Equatorial Spread F on Relative Orbit Determination of GRACE Using Differenced GPS Observations

    Directory of Open Access Journals (Sweden)

    Kyoung-Min Roh

    2009-12-01

    Full Text Available In this paper, relative orbit of Low Earth Orbit satellites is determined using only GPS measurements and the effects of Equatorial Spread-F (ESF, that is one of biggest ionospheric irregularities, are investigated. First, relative orbit determiation process is constructed based on doubly differenced GPS observations. In order to see orbit determination performance, relative orbit of two GRACE satellites is estimated for one month in 2004 when no ESF is observed. The root mean square of the achieved baselines compared with that from K-Band Ranger sensor is about 2 ~ 3 mm and average of 95% of ambiguities are resolved. Based on this performance, the relative orbit is estimated for two weeks of two difference years, 2003 when there are lots of ESF occurred, and 2004 when only few ESF occurred. For 2003, the averaged baseline error over two weeks is about 15 mm. That is about 4 times larger than the case of 2004 (3.6 mm. Ionospheric status achieved from K-Band Ranging sensor also shows that more Equatorial Spread-F occurred at 2003 than 2004. Investigation on raw observations and screening process revealed that the ionospheric irregualarities caused by Equatorial Spread-F gave significant effects on GPS signal like signal loss or enhancement ionospheric error, From this study, relative orbit determination using GPS observations should consider the effect of Equatorial Spread-F and adjust orbit determination strategy, especially at the time of solar maximum.

  4. Observational evidence of mixed rossby gravity waves at the central equatorial Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Muraleedharan, P.M.; PrasannaKumar, S.; Mohankumar, K.; Sijikumar, S.; Sivakumar, K.U.; Mathew, T.

    Six-hourly soundings (GPS sonde) were carried out at the central equatorial Indian Ocean (80º–83ºE) during 25th September–10th October 2011 under the CINDY2011 (Cooperative Indian Ocean Experiment on Intra-seasonal variability in Year 2011) field...

  5. Nutrient characteristics of the water masses and their seasonal variability in the eastern equatorial Indian Ocean.

    Science.gov (United States)

    Sardessai, S; Shetye, Suhas; Maya, M V; Mangala, K R; Prasanna Kumar, S

    2010-01-01

    Nutrient characteristics of four water masses in the light of their thermohaline properties are examined in the eastern Equatorial Indian Ocean during winter, spring and summer monsoon. The presence of low salinity water mass with "Surface enrichments" of inorganic nutrients was observed relative to 20 m in the mixed layer. Lowest oxygen levels of 19 microM at 3 degrees N in the euphotic zone indicate mixing of low oxygen high salinity Arabian Sea waters with the equatorial Indian Ocean. The seasonal variability of nutrients was regulated by seasonally varying physical processes like thermocline elevation, meridional and zonal transport, the equatorial undercurrent and biological processes of uptake and remineralization. Circulation of Arabian Sea high salinity waters with nitrate deficit could also be seen from low N/P ratio with a minimum of 8.9 in spring and a maximum of 13.6 in winter. This large deviation from Redfield N/P ratio indicates the presence of denitrified high salinity waters with a seasonal nitrate deficit ranging from -4.85 to 1.52 in the Eastern Equatorial Indian Ocean. 2010 Elsevier Ltd. All rights reserved.

  6. Some effects of a mean zonal thermocline gradient on planetary equatorial waves

    Directory of Open Access Journals (Sweden)

    M. Pontaud

    1995-11-01

    Full Text Available Planetary equatorial waves are studied with the shallow water equations in the presence of a mean zonal thermocline gradient. The interactions between this gradient and waves are represented by three non-linear terms in the equations: one in the wind-forcing formulation in the x-momentum equation, and two for the advection of mass and divergence of the velocity field in the continuity equation. When the mean gradient is imposed but small, these three (linearized terms will perturb the behaviour of the equatorial waves. This paper gives a simple analytic treatment of this problem. The equatorial Kelvin mode is first solved with all three contributions, using a Wentzel-Kramers-Brillouin method. The Kelvin mode shows a spatial or/and temporal growth when the thermocline gradient is negative which is the usual situation in the equatorial Pacific ocean (deep thermocline in the west and shallow in the east. The more robust and efficient contribution comes from the advection term. The single effect of the advection of the mean zonal thermocline gradient is then studied for the Kelvin and planetary Rossby modes. The Kelvin mode remains unstable (damped, while the Rossby modes appear damped (unstable for a negative (positive thermocline gradient.

  7. Interannual variability of the Equatorial Jets in the Indian Ocean from the merged altimetry data

    Digital Repository Service at National Institute of Oceanography (India)

    Somayajulu, Y.K.; Murty, V.S.N.; Neelima, C.; Jagadeesh, P.S.V.

    jet extended for longer duration than the spring jet. The equatorial Kelvin wave with a wavelength of ~1100 km was identified. Westward propagating Rossby wave was identified at 5° N more clearly. The zonal currents at 5° N (south of Sri Lanka...

  8. Equatorial anomaly variability as a function of the local time and the longitude

    CERN Document Server

    Pulinets, S A; Hernández-Pajáres, M

    2002-01-01

    The equatorial anomaly dynamics is very difficult to study due to necessity of its monitoring in space (latitude-longitude) and local time simultaneously. This task is impossible for the single-point measurements, and only the satellite technology may help. The present paper is devoted to the preliminary analysis of the equatorial anomaly dynamics combining two techniques - the topside sounding and GPS TEC measurements. The topside sounding gives the unique opportunity to build the global structure of the equatorial anomaly for the fixed local time (LT-maps) and to reveal the longitudinal variations, while the chains of GPS receivers along the meridian permit to study the latitudinal variations of TEC in local time. Two meridional chains of GPS receivers were selected: at 115 deg. E and 70 deg. W longitudes. Combining of two technologies makes it possible to obtain three-dimensional global dynamics of the equatorial anomaly. The paper demonstrates the power of the technique itself while the more detailed and ...

  9. Equatorial electrodynamics and neutral background in the Asian sector during the 2009 stratospheric sudden warming

    NARCIS (Netherlands)

    Liu, H.; Yamamoto, M.; Tulasi Ram, S.; Tsugawa, T.; Otsuka, Y.; Stolle, C.; Doornbos, E.; Yumoto, K.; Nagatsuma, T.

    2011-01-01

    Using ground observations of total electron content (TEC) and equatorial electrojet (EEJ) in the Asian sector, along with plasma and neutral densities obtained from the CHAMP satellite, we investigate the ionospheric electrodynamics and neutral background in this longitude sector during the major

  10. Intensities and spatiotemporal variability of equatorial noise emissions observed by the Cluster spacecraft

    Czech Academy of Sciences Publication Activity Database

    Němec, F.; Santolík, Ondřej; Hrbáčková, Zuzana; Cornilleau-Wehrlin, N.

    2015-01-01

    Roč. 120, č. 3 (2015), s. 1620-1632 ISSN 2169-9380 R&D Projects: GA MŠk(CZ) LH11122 Institutional support: RVO:68378289 Keywords : equatorial noise * magnetosonic waves Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 3.318, year: 2015 http://onlinelibrary.wiley.com/doi/10.1002/2014JA020814/full

  11. Response of the Equatorial Ionosphere to the Geomagnetic DP2 current system

    Science.gov (United States)

    Yizengaw, E.; Moldwin, M.; Zesta, E.; Pradipta, R.; Biouele, C. M.; Rabiu, A. B.; Obrou, O.; Bamba, Z.

    2016-12-01

    The response of equatorial ionosphere to the magnetospheric origin DP2 (disturbance polar of the second type) current fluctuations and its impact on the equatorial ionospheric density structure is examined using ground-based multi-instrument observations. The interaction between the solar wind and magnetosphere generates a convection electric field that can penetrate to the ionosphere and cause the DP2 current system. The quasi-periodic DP2 current system, which fluctuates coherently with IMF Bz oscillations, penetrates nearly instantaneously to the dayside equatorial region through the TM0 (zero order transverse magnetic) mode waves in the Earth-ionosphere waveguide and modulates the electrodynamics that are responsible for the complicated nature of dayside ionospheric density variations at the equator. In this paper, using multi-instrument (magnetometers, GPS, radar, and ionosonde) observations, we clearly demonstrated that the high-latitude DP2 current system penetrates to the equator and causes the dayside electrodynamics and ionospheric density to fluctuate coherently with the DP2 current as well as with the IMF Bz component. This clearly indicates that understanding of the quasi-periodic DP2 current systems, such as its source, condition of its penetration to the equatorial region, and the impact it can produce onto the ionospheric density distribution is very important information for the ongoing modeling effort to improve the global ionospheric density structure and scintillation forecasting capability.

  12. The Equatorial Undercurrent in the central Atlantic and its relation to tropical Atlantic variability

    NARCIS (Netherlands)

    Brandt, Peter; Funk, Andreas; Tantet, Alexis; Johns, William E.; Fischer, Jürgen

    2014-01-01

    Seasonal to interannual variations of the Equatorial Undercurrent (EUC) in the central Atlantic at 23?Ware studied using shipboard observation taken during the period 1999–2011 as well as moored velocity time series covering the period May 2005–June 2011. The sea- sonal variations are dominated by

  13. The heat and moisture budgets of the atmosphere over central equatorial Indian Ocean during summer monsoon

    Digital Repository Service at National Institute of Oceanography (India)

    Sadhuram, Y.; Gopalakrishna, V.V.; RameshBabu, V.; Sastry, J.S.

    The heat and moisture budgets of the atmosphere (surface to 100 mb) over the central equatorial Indian Ocean (2 degrees N to 2 degrees S; 76 degrees E to 80 degrees E) have been investigated utilising the surface and upper air data collected...

  14. Equatorial plasma bubbles and L-band scintillations in Africa during solar minimum

    Directory of Open Access Journals (Sweden)

    V. V. Paznukhov

    2012-04-01

    Full Text Available We report on the longitudinal, local time and seasonal occurrence of equatorial plasma bubbles (EPBs and L band (GPS scintillations over equatorial Africa. The measurements were made in 2010, as a first step toward establishing the climatology of ionospheric irregularities over Africa. The scintillation intensity is obtained by measuring the standard deviation of normalized GPS signal power. The EPBs are detected using an automated technique, where spectral analysis is used to extract and identify EPB events from the GPS TEC measurements. Overall, the observed seasonal climatology of the EPBs as well as GPS scintillations in equatorial Africa is adequately explained by geometric arguments, i.e., by the alignment of the solar terminator and local geomagnetic field, or STBA hypothesis (Tsunoda, 1985, 2010a. While plasma bubbles and scintillations are primarily observed during equinoctial periods, there are longitudinal differences in their seasonal occurrence statistics. The Atlantic sector has the most intense, longest lasting, and highest scintillation occurrence rate in-season. There is also a pronounced increase in the EPB occurrence rate during the June solstice moving west to east. In Africa, the seasonal occurrence shifts towards boreal summer solstice, with fewer occurrences and shorter durations in equinox seasons. Our results also suggest that the occurrence of plasma bubbles and GPS scintillations over Africa are well correlated, with scintillation intensity depending on depletion depth. A question remains about the possible physical mechanisms responsible for the difference in the occurrence phenomenology of EPBs and GPS scintillations between different regions in equatorial Africa.

  15. An Enduring Rapidly Moving Storm as a Guide to Saturn's Equatorial Jet's Complex Structure

    Science.gov (United States)

    Sanchez-Lavega, A.; Garcia-Melendo, E.; Perez-Hoyos, S.; Hueso, R.; Wong, M. H.; Simon, A.; Sanz-Requena, J. F.; Antunano, A.; Barrado-Izagirre, N.; Garate-Lopez, I.; hide

    2016-01-01

    Saturn has an intense and broad eastward equatorial jet with a complex three-dimensional structure mixed with time variability. The equatorial region experiences strong seasonal insolation variations enhanced by ring shadowing, and three of the six known giant planetary-scale storms have developed in it. These factors make Saturn's equator a natural laboratory to test models of jets in giant planets. Here we report on a bright equatorial atmospheric feature imaged in 2015 that moved steadily at a high speed of 450/ms not measured since 1980-1981 with other equatorial clouds moving within an ample range of velocities. Radiative transfer models show that these motions occur at three altitude levels within the upper haze and clouds. We find that the peak of the jet (latitudes 10degN to 10degS) suffers intense vertical shears reaching + 2.5/ms/km, two orders of magnitude higher than meridional shears, and temporal variability above 1 bar altitude level.

  16. Synthesis, structure and property of diorganotin complexes with chiral N-(5-chlorosalicylidene)valinate ligand

    Science.gov (United States)

    Tian, Laijin; Yao, Yanze; Wang, Yuhua; Liu, Jin

    2018-03-01

    Six new diorganotin N-[(5-chloro-2-oxyphenyl)methylene]valinates, R2SnL (R = Me, 1; Et, 2; L = 5-Cl-2-OC6H3CH = NCH(i-Pr)COO: (S)-, a; (R)-, b; (RS)-, c), have been synthesized from the reaction of R2SnCl2 with the chiral ligand KHL (potassium salt of HL) in different solvents and characterized by elemental analysis, IR, NMR (1H, 13C and 119Sn) spectra. In benzene, the configuration of the chiral ligand was retained. (S)-Enantiomers (1a and 2a) and (R)-enantiomers (1b and 2b) display discrete molecular structures with distorted trigonal bipyramidal geometries in which two C atoms of organic groups (R) and the imino N atom occupy the equatorial positions and a phenoxide O and an unidentate carboxylate group O atom are in the axial orientation. In the methanol, the chiral ligand was racemized. 1cṡMeOH is a centrosymmetric dimers formed by (R)- and (S)- enantiomers through two Snsbnd OṡṡṡSn bridges. The coordination geometry of the Sn atom can be described as a distorted pentagonal bipyramid with two methyl groups in axial positions. The crystal of 2c is composed of two threefold symmetric trimers, a [Et2SnL-(R)]3 and a [Et2SnL-(S)]3, with a macrocyclic 12-membered ring structure formed by the bidenate bridging coordination of carboxylate group to tin atoms. Each tin atom is six-coordinated in distorted [SnC2NO3] octahedron geometry. The fluorescence properties of ligand KHL and complexes 1 (1a-1c) and 2 (2a-2c) have been measured. The results show the complexes may be explored for potential luminescent materials.

  17. Macrocyclic ligands for uranium complexation. Final report, August 1, 1986--March 31, 1993

    International Nuclear Information System (INIS)

    Potts, K.T.

    1993-01-01

    Macrocycles, designed for complexation of the uranyl ion by computer modeling studies and utilizing six ligating atoms in the equatorial plane of the uranyl ions, have been prepared and their complexation of the uranyl ions evaluated. The ligating atoms, either oxygen or sulfur, were part of acylurea, biuret or thiobiuret subunits with alkane chains or pyridine units completing the macrocyclic periphery. These macrocycles with only partial preorganization formed uranyl complexes in solution but no crystalline complexes were isolated. Refinement of the cavity diameter by variation of the peripheral functional groups is currently studied to achieve an optimized cavity diameter of 4.7--5.2 angstrom. Acyclic ligands containing the same ligating atoms in equivalent functional entities were found to form a crystalline 1:1 uranyl-ligand complex (stability constant log K = 10.7) whose structure was established by X-ray data. This complex underwent a facile, DMSO-induced rearrangement to a 2:1 uranyl-ligand complex whose structure was also established by X-ray data. The intermediates to the macrocycles all behaved as excellent ligands for the complexation of transition metals. Acylthiourea complexes of copper and nickel as well as intermolecular, binuclear copper and nickel complexes of bidentate carbonyl thioureas formed readily and their structures were established in several representative instances by X-ray structural determinations. Tetradentate bis(carbonylthioureas) were found to be very efficient selective reagents for the complexation of copper in the presence of nickel ions. Several preorganized macrocycles were also prepared but in most instances these macrocycles underwent ring-opening under complexation conditions

  18. Macrocyclic ligands for uranium complexation. Final report, August 1, 1986--March 31, 1993

    Energy Technology Data Exchange (ETDEWEB)

    Potts, K.T.

    1993-12-31

    Macrocycles, designed for complexation of the uranyl ion by computer modeling studies and utilizing six ligating atoms in the equatorial plane of the uranyl ions, have been prepared and their complexation of the uranyl ions evaluated. The ligating atoms, either oxygen or sulfur, were part of acylurea, biuret or thiobiuret subunits with alkane chains or pyridine units completing the macrocyclic periphery. These macrocycles with only partial preorganization formed uranyl complexes in solution but no crystalline complexes were isolated. Refinement of the cavity diameter by variation of the peripheral functional groups is currently studied to achieve an optimized cavity diameter of 4.7--5.2 {angstrom}. Acyclic ligands containing the same ligating atoms in equivalent functional entities were found to form a crystalline 1:1 uranyl-ligand complex (stability constant log K = 10.7) whose structure was established by X-ray data. This complex underwent a facile, DMSO-induced rearrangement to a 2:1 uranyl-ligand complex whose structure was also established by X-ray data. The intermediates to the macrocycles all behaved as excellent ligands for the complexation of transition metals. Acylthiourea complexes of copper and nickel as well as intermolecular, binuclear copper and nickel complexes of bidentate carbonyl thioureas formed readily and their structures were established in several representative instances by X-ray structural determinations. Tetradentate bis(carbonylthioureas) were found to be very efficient selective reagents for the complexation of copper in the presence of nickel ions. Several preorganized macrocycles were also prepared but in most instances these macrocycles underwent ring-opening under complexation conditions.

  19. Bell inequalities stronger than the Clauser-Horne-Shimony-Holt inequality for three-level isotropic states

    International Nuclear Information System (INIS)

    Ito, Tsuyoshi; Imai, Hiroshi; Avis, David

    2006-01-01

    We show that some two-party Bell inequalities with two-valued observables are stronger than the CHSH inequality for 3x3 isotropic states in the sense that they are violated by some isotropic states in the 3x3 system that do not violate the CHSH inequality. These Bell inequalities are obtained by applying triangular elimination to the list of known facet inequalities of the cut polytope on nine points. This gives a partial solution to an open problem posed by Collins and Gisin. The results of numerical optimization suggest that they are candidates for being stronger than the I 3322 Bell inequality for 3x3 isotropic states. On the other hand, we found no Bell inequalities stronger than the CHSH inequality for 2x2 isotropic states. In addition, we illustrate an inclusion relation among some Bell inequalities derived by triangular elimination

  20. Ligand photo-isomerization triggers conformational changes in iGluR2 ligand binding domain.

    Directory of Open Access Journals (Sweden)

    Tino Wolter

    Full Text Available Neurological glutamate receptors bind a variety of artificial ligands, both agonistic and antagonistic, in addition to glutamate. Studying their small molecule binding properties increases our understanding of the central nervous system and a variety of associated pathologies. The large, oligomeric multidomain membrane protein contains a large and flexible ligand binding domains which undergoes large conformational changes upon binding different ligands. A recent application of glutamate receptors is their activation or inhibition via photo-switchable ligands, making them key systems in the emerging field of optochemical genetics. In this work, we present a theoretical study on the binding mode and complex stability of a novel photo-switchable ligand, ATA-3, which reversibly binds to glutamate receptors ligand binding domains (LBDs. We propose two possible binding modes for this ligand based on flexible ligand docking calculations and show one of them to be analogues to the binding mode of a similar ligand, 2-BnTetAMPA. In long MD simulations, it was observed that transitions between both binding poses involve breaking and reforming the T686-E402 protein hydrogen bond. Simulating the ligand photo-isomerization process shows that the two possible configurations of the ligand azo-group have markedly different complex stabilities and equilibrium binding modes. A strong but slow protein response is observed after ligand configuration changes. This provides a microscopic foundation for the observed difference in ligand activity upon light-switching.

  1. Ruthenium Cumulenylidene Complexes Bearing Heteroscorpionate Ligands

    OpenAIRE

    Strinitz, Frank

    2014-01-01

    In previous work of the BURZLAFF group, the design of suitable N,N,O ligands for a wide variety of applications ranging from catalysis to bioinorganic model compounds has been extensively investigated. Especially the methyl substituted bis(3,5-dimethylpyrazol-1-yl) acetate (bdmpza) ligand has shown manifold chemistry, comparable to the anionic cyclopentadienyl (Cp) and hydridotris(pyrazol-1-yl)borato (Tp) ligand. In the first part of this thesis the new tricarbonylmanganese(I) complexes be...

  2. Gas-phase complexes formed between amidoxime ligands and vanadium or iron investigated using electrospray ionization mass spectrometry.

    Science.gov (United States)

    Mustapha, Adetayo M; Pasilis, Sofie P

    2016-08-15

    Amidoxime-functionalized sorbents can be used to extract uranium from seawater. Iron(III) and vanadium(V) may compete with uranium for adsorption sites. We use 2,6-dihydroxyiminopiperidine (DHIP) and N(1) ,N(5) -dihydroxypentanediimidamide (DHPD) to model amidoxime functional groups and characterize the vanadium(V) and iron(III) complexes with these ligands. We also examine the effect of iron(III) and vanadium(V) on uranyl(VI) complexation by DHIP and DHPD. The experiments were carried out in positive ion mode using a quadrupole ion trap mass spectrometer equipped with an electrospray ionization source. The effect on the mass spectra of changes in ligand, metal:ligand mole ratio, and pH was examined. Iron(III) formed a 1:2 metal:ligand complex with DHIP at all metal:ligand mole ratios and pH values investigated; it formed both 1:2 and 1:3 metal:ligand complexes with DHPD. Vanadium(V) formed 1:1 and 1:2 metal:ligand complexes with DHIP. A 1:2 metal:ligand complex was formed with DHPD at all vanadium(V):DHPD mole ratios investigated. Changes in solution pH did not affect the ions observed. The relative binding affinities of the metal ions towards DHIP followed the order iron(III) > vanadium(V) > uranyl(VI). This study presents a first look at the gas-phase vanadium(V)- and iron(III)-DHIP and -DHPD complexes using electrospray ionization mass spectrometry. These metals form stronger complexes with amidoxime ligands than uranyl(VI), and will affect uranyl(VI) adsorption to amidoxime-based sorbents. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

  3. "This one is stronger". Spotlights on the lifelong learning professional-in-action

    Directory of Open Access Journals (Sweden)

    Josje van der Linden

    2016-06-01

    Full Text Available ABSTRACT“This one is stronger.” Spotlights on the lifelong learning professional-in-action Around the world, lifelong learning is being promoted as a strategy for coping with the changing realities of life and work. The fourth Sustainable Development Goal, agreed in September 2015, reflects this: “ensure equitable and inclusive quality education and promote lifelong learning opportunities for all”. Despite its importance, doubts remain about the implementation of this goal in practice (Van der Kamp, 2000; Regmi, 2015. This article looks at the practice of lifelong learning from the point of view of the professionals involved, their actions and the way these actions are challenged, supported and further developed. Following Schön’s “reflection-in-action” (1983, the term “professional-in-action” is used to stress the role of the professional in making the difference on the ground. The leading question is: how can lifelong learning professionals be supported in their contribution to surrounding society and its citizens? The professionals-in-action featured in this article include professionals based in the Netherlands as well as in other, less privileged contexts. Meaningful experiences are used to build a story about challenges, the right to exist, commitment, recognition and room to manoeuvre. The experiences reveal the importance of interacting with the learner and the professional space that is necessary to achieve this. Professionalization in professional learning communities and practice-oriented research must accompany this professional space. SAMENVATTING“Deze is sterker”. Spotlights op de leven lang leren professional-in-actieOm te kunnen omgaan met de veranderende realiteit in leven en werk, wordt wereldwijd een leven lang leren aangemoedigd. Het vierde duurzame ontwikkelingsdoel, vastgesteld in september 2015, weerspiegelt dit: “het verzekeren van kwalitatief goed onderwijs en het bevorderen van de mogelijkheden

  4. Development of immobilized ligands for actinide separations

    International Nuclear Information System (INIS)

    Paine, R.T.

    1994-01-01

    Primary goals during this grant period were to (1) synthesize new bifunctional chelating ligands, (2) characterize the structural features of the Ln and An coordination complexes formed by these ligands, (3) use structural data to iteratively design new classes of multifunctional ligands, and (4) explore additional routes for attachment of key ligands to solid supports that could be useful for chromatographic separations. Some highlights of recently published work as well as a summary of submitted, unpublished and/or still in progress research are outlined

  5. Synthesis, Characterization, DNA Interaction, and Antitumor Activities of La (III) Complex with Schiff Base Ligand Derived from Kaempferol and Diethylenetriamine.

    Science.gov (United States)

    Wang, Qin; Huang, Yu; Zhang, Jin-Sheng; Yang, Xin-Bin

    2014-01-01

    A novel La (III) complex, [LaL(H2O)3]NO3 ·3H2O, with Schiff base ligand L derived from kaempferol and diethylenetriamine, has been synthesized and characterized by elemental analysis, IR, UV-visible, (1)H NMR, thermogravimetric analysis, and molar conductance measurements. The fluorescence spectra, circular dichroism spectra, and viscosity measurements and gel electrophoresis experiments indicated that the ligand L and La (III) complex could bind to CT-DNA presumably via intercalative mode and the La (III) complex showed a stronger ability to bind and cleave DNA than the ligand L alone. The binding constants (K b ) were evaluated from fluorescence data and the values ranged from 0.454 to 0.659 × 10(5) L mol(-1) and 1.71 to 17.3 × 10(5) L mol(-1) for the ligand L and La (III) complex, respectively, in the temperature range of 298-310 K. It was also found that the fluorescence quenching mechanism of EB-DNA by ligand L and La (III) complex was a static quenching process. In comparison to free ligand L, La (III) complex exhibited enhanced cytotoxic activities against tested tumor cell lines HL-60 and HepG-2, which may correlate with the enhanced DNA binding and cleaving abilities of the La (III) complex.

  6. Synthesis and photoluminescence properties of novel Schiff base type polymer-rare earth complexes containing furfural-based bidentate Schiff base ligands

    Science.gov (United States)

    Gao, Baojiao; Zhang, Dandan; Li, Yanbin

    2018-03-01

    Luminescent polymer-rare earth complexes are an important class of photoluminescence and electroluminescence materials. Via molecular design, two furfural-based bidentate Schiff base ligands, furfural-aniline (FA) type ligand and furfural-cyclohexylamine (FC) type ligand, were bonded on the side chains of polysulfone (PSF), respectively, forming two functionalized macromolecules, PSF-FA and PSF-FC. And then through respective coordination reactions of the two functionalized macromolecules with Eu(Ⅲ) ion and Tb(Ⅲ) ion, novel luminescent binary and ternary (with 1,10-phenanthroline as the second ligand) polymer-rare earth complexes were synthesized. For these complexes, on basis of the characterization of their chemical structures, they photoluminescence properties were main researched, and the relationship between their luminescent properties and structures was explored. The experimental results show that the complexes coming from PSF-FA and Eu(Ⅲ) ion including binary and ternary complexes emit strong red luminescence, indicating that the bonded bidentate Schiff base ligand FA can sensitize the fluorescence emission of Eu(III) ion. While the complexes coming from PSF-FC and Tb(Ⅲ) ion produce green luminescence, displaying that the bonded bidentate Schiff base ligand FC can sensitize the fluorescence emission of Tb(Ⅲ) ion. The fluorescence emission intensities of the ternary complexes were stronger than that of binary complexes, reflecting the important effect of the second ligand. The fluorescence emission of the solid film of complexes is much stronger than that of the solutions of complexes. Besides, by comparison, it is found that the furfural (as a heteroaromatic compound)-based Schiff base type polymer-rare earth complexes have stronger fluorescence emission and higher energy transfer efficiency than salicylaldehyde (as a common aromatic compound)-based Schiff base type polymer-rare earth complexes.

  7. Stronger Association Between Valence- and Arousal Ratings of Affective Pictures with Older Age: Evidence for Variation Across Emotion Categories

    DEFF Research Database (Denmark)

    Mikkelsen, Mai Bjørnskov; Mehlsen, Mimi Yung; Lyby, Marlene Skovgaard

    A sample of older and younger adults rated affective pictures according to valence, arousal and emotion category (happiness, sadness and disgust). Results indicate that older age is associated with a stronger linear association between ratings of arousal and valence. Further, the strength...

  8. Pilot testing of the "First You Should Get Stronger" program among caregivers of older adults with dementia.

    Science.gov (United States)

    Lök, Neslihan; Bademli, Kerime

    In this study, randomized controlled interventional study pattern was used to examine the effects of the "First You Should Get Stronger" program on the caregiving burden and healthy life style behavior of caregivers of dementia patients. "Zarit Caregiver Burden Scale" and "Healthy Life Style Behavior Scale" were used. The study was completed with 40 caregivers in total with 20 in the intervention group and 20 in the control group. A statistically significant difference was determined between the "Zarit Caregiving Burden Scale" and "Healthy Life Style Behavior Scale" score averages of the intervention group that participated in the "First You Should Get Stronger" program in comparison with those of the control group. It is important for the healths of caregivers to include similar programs for the caregivers of dementia patients in continuous and regular applications. The results highlight the importance of the "First You Should Get Stronger" program significantly decreased the caregiving burden and significantly developed the healthy lifestyle behaviors of caregivers in the intervention group. Since dementia is a difficult neurological syndrome with patients cared at home, it generally wears out the caregivers significantly. It is suggested that the nurses and healthcare professionals working with dementia patients are evaluated separately and that they carry out caregiving applications within the scope of the "First You Should Get Stronger" program. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  9. Equatorial ionospheric electrodynamics observations in the African and American longitudinal sectors

    Science.gov (United States)

    Yizengaw, E.; Moldwin, M.; Mebrahtu, A.; Damtie, B.; Pfaff, R. F.; Zesta, E.; Valladares, C. E.

    2009-12-01

    Recent ground- and space-based observations have shown dramatic longitudinal differences in equatorial ionospheric electrodynamics, such as enhanced generation of F-region plasma irregularities and the super fountain effect at low latitudes. For example, satellite observations have shown very unique equatorial ionospheric density structures in the African region. The African region is the longitude sector where the peak in large scale plasma depletion activity (zonal width, depletion level, and spacing) is maximal, in which no other region of the globe showed similar characteristics. Indeed, the most recent in situ density observations from the Communication/Navigation Outage Forecast System (C/NOFS) satellite also reveal similar maximal density depletion activities in Africa. However, the dearth of ground-based instrumentation in the region makes it difficult to confirm the ground-based signatures of these unique equatorial ionospheric structures, ultimately leading the investigation of their physics into speculation. This initiated several open questions, which include: What are the possible governing mechanisms that create unique equatorial structures in Africa? In order to answer such open questions, recently limited progress has been made and very few ground-based instruments, including the AMBER magnetometers network, have been deployed in the region. One of many objectives of AMBER magnetometers network, in coordination with ground- and space-based GPS receiver observations, is to understand the fundamental electrodynamics that govern equatorial ionospheric motion, which includes the evolution and formation of equatorial anomaly. This paper presents initial results from the AMBER magnetometer network and compares electrodynamics results in the Africa sector with similar observations in the American sector. The electron density structure in response to the electrodynamics is also investigated using the available ground-based GPS receivers in the region as

  10. Ligand Binding Affinities of Arctigenin and Its Demethylated Metabolites to Estrogen Receptor Alpha

    Directory of Open Access Journals (Sweden)

    Masao Hattori

    2013-01-01

    Full Text Available Phytoestrogens are defined as plant-derived compounds with estrogen-like activities according to their chemical structures and activities. Plant lignans are generally categorized as phytoestrogens. It was reported that (−-arctigenin, the aglycone of arctiin, was demethylated to (−-dihydroxyenterolactone (DHENL by Eubacterium (E. sp. ARC-2. Through stepwise demethylation, E. sp. ARC-2 produced six intermediates, three mono-desmethylarctigenins and three di-desmethylarctigenins. In the present study, ligand binding affinities of (−-arctigenin and its seven metabolites, including DHENL, were investigated for an estrogen receptor alpha, and found that demethylated metabolites had stronger binding affinities than (−-arctigenin using a ligand binding screen assay method. The IC50 value of (2R,3R-2-(4-hydroxy-3-methoxybenzyl-3-(3,4-dihydroxybenzyl-butyrolactone was 7.9 × 10−4 M.

  11. Ligand binding affinities of arctigenin and its demethylated metabolites to estrogen receptor alpha.

    Science.gov (United States)

    Jin, Jong-Sik; Lee, Jong-Hyun; Hattori, Masao

    2013-01-16

    Phytoestrogens are defined as plant-derived compounds with estrogen-like activities according to their chemical structures and activities. Plant lignans are generally categorized as phytoestrogens. It was reported that (-)-arctigenin, the aglycone of arctiin, was demethylated to (-)-dihydroxyenterolactone (DHENL) by Eubacterium (E.) sp. ARC-2. Through stepwise demethylation, E. sp. ARC-2 produced six intermediates, three mono-desmethylarctigenins and three di-desmethylarctigenins. In the present study, ligand binding affinities of (-)-arctigenin and its seven metabolites, including DHENL, were investigated for an estrogen receptor alpha, and found that demethylated metabolites had stronger binding affinities than (-)-arctigenin using a ligand binding screen assay method. The IC(50) value of (2R,3R)-2-(4-hydroxy-3-methoxybenzyl)-3-(3,4-dihydroxybenzyl)-butyrolactone was 7.9 × 10⁻⁴ M.

  12. Macrocyclic ligands for uranium complexation

    Energy Technology Data Exchange (ETDEWEB)

    Potts, K.T.

    1991-04-01

    A highly preorganized 24-macrocycle containing biuret, thiobiuret and pyridine subunits has been prepared by high dilution ring-closure procedures. Intermediate products to this macrocycle have been utilized to extend this synthetic route to include further representatives where solubility and stability will be influenced by substituent variation. A 1:1 complex has been formed from uranyl acetate and a quinquepyridine derivative, this representing a new type of ligand for the uranyl ion. A very convenient synthetic procedure that will allow the incorporation of these macrocycles into polymeric systems has been developed for the introduction of a vinyl substituent into the 4-position of the pyridine ring. Using triflate, vinyltributyltin and Pd{sup 0} chemistry, this procedure should make a variety of substituted 4-vinylpyridines available for the first time. 3 refs.

  13. Macrocyclic ligands for uranium complexation

    International Nuclear Information System (INIS)

    Potts, K.T.

    1991-04-01

    A highly preorganized 24-macrocycle containing biuret, thiobiuret and pyridine subunits has been prepared by high dilution ring-closure procedures. Intermediate products to this macrocycle have been utilized to extend this synthetic route to include further representatives where solubility and stability will be influenced by substituent variation. A 1:1 complex has been formed from uranyl acetate and a quinquepyridine derivative, this representing a new type of ligand for the uranyl ion. A very convenient synthetic procedure that will allow the incorporation of these macrocycles into polymeric systems has been developed for the introduction of a vinyl substituent into the 4-position of the pyridine ring. Using triflate, vinyltributyltin and Pd 0 chemistry, this procedure should make a variety of substituted 4-vinylpyridines available for the first time. 3 refs

  14. Extent of enthalpy–entropy compensation in protein–ligand interactions

    Science.gov (United States)

    Olsson, Tjelvar S G; Ladbury, John E; Pitt, Will R; Williams, Mark A

    2011-01-01

    The extent of enthalpy–entropy compensation in protein–ligand interactions has long been disputed because negatively correlated enthalpy (ΔH) and entropy (TΔS) changes can arise from constraints imposed by experimental and analytical procedures as well as through a physical compensation mechanism. To distinguish these possibilities, we have created quantitative models of the effects of experimental constraints on isothermal titration calorimetry (ITC) measurements. These constraints are found to obscure any compensation that may be present in common data representations and regression analyses (e.g., in ΔH vs. –TΔS plots). However, transforming the thermodynamic data into ΔΔ-plots of the differences between all pairs of ligands that bind each protein diminishes the influence of experimental constraints and representational bias. Statistical analysis of data from 32 diverse proteins shows a significant and widespread tendency to compensation. ΔΔH versus ΔΔG plots reveal a wide variation in the extent of compensation for different ligand modifications. While strong compensation (ΔΔH and −TΔΔS opposed and differing by enthalpy and entropy changes arise from changes to the distribution of energy states on binding, there is a general theoretical expectation of compensated behavior. However, prior theoretical studies have focussed on explaining a stronger tendency to compensation than actually found here. These results, showing strong but imperfect compensation, will act as a benchmark for future theoretical models of the thermodynamic consequences of ligand modification. PMID:21739503

  15. Ab initio calculation of transport properties between PbSe quantum dots facets with iodide ligands

    Science.gov (United States)

    Wang, B.; Patterson, R.; Chen, W.; Zhang, Z.; Yang, J.; Huang, S.; Shrestha, S.; Conibeer, G.

    2018-01-01

    The transport properties between Lead Selenide (PbSe) quantum dots decorated with iodide ligands has been studied using density functional theory (DFT). Quantum conductance at each selected energy levels has been calculated along with total density of states and projected density of states. The DFT calculation is carried on using a grid-based planar augmented wave (GPAW) code incorporated with the linear combination of atomic orbital (LCAO) mode and Perdew Burke Ernzerhof (PBE) exchange-correlation functional. Three iodide ligand attached low index facets including (001), (011), (111) are investigated in this work. P-orbital of iodide ligand majorly contributes to density of state (DOS) at near top valence band resulting a significant quantum conductance, whereas DOS of Pb p-orbital shows minor influence. Various values of quantum conductance observed along different planes are possibly reasoned from a combined effect electrical field over topmost surface and total distance between adjacent facets. Ligands attached to (001) and (011) planes possess similar bond length whereas it is significantly shortened in (111) plane, whereas transport between (011) has an overall low value due to newly formed electric field. On the other hand, (111) plane with a net surface dipole perpendicular to surface layers leading to stronger electron coupling suggests an apparent increase of transport probability. Apart from previously mentioned, the maximum transport energy levels located several eVs (1 2 eVs) from the edge of valence band top.

  16. Ligand based pharmacophore modelling of anticancer histone ...

    African Journals Online (AJOL)

    USER

    2010-06-21

    Jun 21, 2010 ... HDAC ligands (Chen et al., 2008b). The knowledge of common properties of the binding group is essential for the determination of the type of inhibitor binding the target. Major goal of modern drug design is identification and development of new ligands with high affinity of binding toward a given protein.

  17. Organometallic chemistry of chiral diphosphazane ligands ...

    Indian Academy of Sciences (India)

    Unknown

    1. Introduction. Diphosphazanes constitute a class of versatile short-bite bidentate P-donor ligands that have given rise to a varied and extensive transition metal organometallic chemistry. The organometallic chemistry of diphosphazane ligands with almost every transition metal in the periodic table is well documented1–3.

  18. Cofactor-Controlled Chirality of Tropoisomeric Ligand

    NARCIS (Netherlands)

    Théveau, L.; Bellini, R.; Dydio, P.; Szabo, Z.; van der Werf, A.; Sander, R.A.; Reek, J.N.H.; Moberg, C.

    2016-01-01

    A new tropos ligand with an integrated anion receptor receptor site has been prepared. Chiral carboxylate and phosphate anions that bind in the anion receptor unit proved capable of stabilizing chiral conformations of the achiral flexible bidentate biaryl phosphite ligand, as shown by variable

  19. Ligand modification for mono- and biphasic oxosynthesis

    Energy Technology Data Exchange (ETDEWEB)

    Haerter, P.; Herrmann, W.A.; Baskakov, D. [Technische Univ. Muenchen (Germany). Dept. Chemie

    2006-07-01

    The use of aqueous/organic biphasic systems has attracted huge interest in catalytic reactions by transition metal complexes. [1,2,3] The biphasic systems have benefits in catalyst separation and recycling, and the reduction or elimination of organic solvents is also advantageous for the development of economical and environmentally friendly processes. The key for such biphasic catalysis is the use of water soluble phosphines as ligands. Since the launch of the commercial propylene hydroformylation process by Ruhrchemie/Rhone-Poulenc, sulfonated ligands such as TPPTS (1), and BINAS (2) have been widely used as ligands in hydroformylation, hydrogenation and related reactions catalyzed by transition metals. One of the draw backs of ligands 1 and 2 are corrosive production conditions and therefore unfavorable costs. With the synthesis of aminoacid based trishydroxymethylphosphine derivatives (THMP-aminoacid) we introduce to our knowledge a new group of water soluble and cheap to produce ligands [8]. The properties of catalysts based on these compounds in the hydroformylation reaction of propene are discussed in comparison to normally used catalyst systems. In a second part the performance of catalysts containing NHC-ligands in the hydroformylation of 1-octene is discussed [9]. These investigations show, that the activity can be influenced by the electron donating ability of the NHC ligand. Sterical variations on the NHC ligands have no effect on the selectivity performance of the the catalysts. (orig.)

  20. Organometallic chemistry of chiral diphosphazane ligands ...

    Indian Academy of Sciences (India)

    Unknown

    organometallic chemistry of diphosphazane ligands with almost every transition metal in the periodic table is well documented1–3. A very attractive feature of diphosphazane ligands is that 'chirality' can be incorporated at the phosphorus centres as well as at the substituents attached to the nitrogen and the two phosphorus ...

  1. Ligand sphere conversions in terminal carbide complexes

    DEFF Research Database (Denmark)

    Morsing, Thorbjørn Juul; Reinholdt, Anders; Sauer, Stephan P. A.

    2016-01-01

    Metathesis is introduced as a preparative route to terminal carbide complexes. The chloride ligands of the terminal carbide complex [RuC(Cl)2(PCy3)2] (RuC) can be exchanged, paving the way for a systematic variation of the ligand sphere. A series of substituted complexes, including the first exam...

  2. Biomimetic affinity ligands for protein purification.

    Science.gov (United States)

    Sousa, Isabel T; Taipa, M Angela

    2014-01-01

    The development of sophisticated molecular modeling software and new bioinformatic tools, as well as the emergence of data banks containing detailed information about a huge number of proteins, enabled the de novo intelligent design of synthetic affinity ligands. Such synthetic compounds can be tailored to mimic natural biological recognition motifs or to interact with key surface-exposed residues on target proteins and are designated as "biomimetic ligands." A well-established methodology for generating biomimetic or synthetic affinity ligands integrates rational design with combinatorial solid-phase synthesis and screening, using the triazine scaffold and analogues of amino acids side chains to create molecular diversity.Triazine-based synthetic ligands are nontoxic, low-cost, highly stable compounds that can replace advantageously natural biological ligands in the purification of proteins by affinity-based methodologies.

  3. Internally and externally induced deformations of the magnetospheric equatorial current as inferred from spacecraft data

    Directory of Open Access Journals (Sweden)

    N. A. Tsyganenko

    2015-01-01

    Full Text Available Based on a data pool of 79 yearly files of space magnetometer data by Polar, Cluster, Geotail, and THEMIS satellites between 1995 and 2013, we developed a new quantitative model of the global shape of the magnetospheric equatorial current sheet as a function of the Earth's dipole tilt angle, solar wind ram pressure, and interplanetary magnetic field (IMF. This work upgrades and generalizes an earlier model of Tsyganenko and Fairfield (2004 by extending the modeling region to all local times, including the dayside sector. In particular, an essential feature of the new model is the bowl-shaped tilt-related deformation of the equatorial surface of minimum magnetic field, similar to that observed at Saturn, whose existence in the Earth's magnetosphere has been demonstrated in our recent work (Tsyganenko and Andreeva, 2014.

  4. Tectonic setting of the Seychelles, Mascarene and Amirante Plateaus in the Western Equatorial Indian Ocean

    International Nuclear Information System (INIS)

    Mart, Y.

    1988-01-01

    A system of marine plateaus occurs in the western equatorial Indian Ocean, forming an arcuate series of wide and shallow banks with small islands in places. The oceanic basins that surround the Seychelles - Amirante region are of various ages and reflect a complex seafloor spreading pattern. The structural analysis of the Seychelle - Amirante - Mascarene region reflects the tectonic evolution of the western equatorial Indian Ocean. It is suggested that due to the seafloor spreading during a tectonic stage, the Seychelles continental block drifted southwestwards to collide with the oceanic crust of the Mascarene Basin, forming an elongated folded structure at first, and then a subduction zone. The morphological similarity, the lithological variability and the different origin of the Seychelles Bank, the Mascarene Plateau and the Amirante Arc emphasizes the significant convergent effects of various plate tectonic processes on the development of marine plateaus

  5. Excitation of electromagnetic proton cyclotron instability by parallel electric field in the equatorial magnetosphere

    International Nuclear Information System (INIS)

    Dixit, S.K.; Azif, Z.A.; Gwal, A.K.

    1994-01-01

    The characteristics of the growth rate of electromagnetic ion cyclotron (EMIC) instability is investigated in a mixture of cold species of ions and warm proton in the presence of weak parallel static electric field. An attempt has been made to explain the excitation of EMIC waves through linear wave-particle (W-P) interaction in the equatorial magnetospheric region. The proton cyclotron instability is modified in presence of weak parallel electric field and the growth rate is computed for equatorial magnetospheric plasma parameters. The results of theoretical investigations of the growth rate are used to explain the excitation mechanism of extremely low frequency/very low frequency (ELF/VLF) waves as observed by satellites. (author). 29 refs., 4 figs

  6. C/NOFS Observations of AC Electric Field Fields Associated with Equatorial Spread-F

    Science.gov (United States)

    Pfaff, R.; Liebrecht, C.

    2009-01-01

    The Vector Electric Field Investigation (VEFI) on the C/NOFS equatorial satellite provides a unique data set in which to acquire detailed knowledge of irregularities associated with the equatorial ionosphere and in particular with spread-F depletions. We present vector AC electric field observations, primarily gathered within the ELF band (1 Hz to 250 Hz) on C/NOFS that address a variety of key questions regarding how plasma irregularities, from meter to kilometer scales, are created and evolve. The data will be used to explore the anisotropy/isotropy of the waves, their wavelength and phase velocity, as well as their spectral distributions. When analyzed in conjunction with the driving DC electric fields and detailed plasma number density measurements, the combined data reveal important information concerning the instability mechanisms themselves. We also present high resolution, vector measurements of intense lower hybrid waves that have been detected on numerous occasions by the VEFI burst memory VLF electric field channels.

  7. Longitudinal, seasonal and solar cycle variation in lunar tide influence on the equatorial electrojet

    Energy Technology Data Exchange (ETDEWEB)

    Yizengaw, Endawoke [Boston College, Chestnut Hill, MA (United States). Inst. for Scientific Research; Carter, Brett A. [RMIT Univ., Melbourne, VIC (Australia). SPACE Research Centre

    2017-07-01

    It has been well documented that the lunar tidal waves can modulate the ionospheric electrodynamics and create a visible influence on the equatorial electrojet (EEJ). The lunar tide influence gets intensified around noon, primarily during new and full Moon periods. However, the longitudinal, seasonal and solar cycle variability in the lunar tide influence on ionospheric current systems is not well understood yet. In order to investigate this, 17 years (1998-2014) of extensive magnetometer observations at four longitudinal sectors (western American, western and eastern African, and Asian) have been analyzed. All observations performed during magnetically active periods (K{sub p}>3) have been excluded for this study to eliminate storm contributions to the geomagnetic field variation at the geomagnetic equator. This study's quantitative analysis revealed significant longitudinal, seasonal and solar cycle dependence of the lunar tide influence on the equatorial electrojet.

  8. Equatorial spread F studies using SAMI3 with two-dimensional and three-dimensional electrostatics

    Directory of Open Access Journals (Sweden)

    H. C. Aveiro

    2013-12-01

    Full Text Available This letter presents a study of equatorial F region irregularities using the NRL SAMI3/ESF model, comparing results using a two-dimensional (2-D and a three-dimensional (3-D electrostatic potential solution. For the 3-D potential solution, two cases are considered for parallel plasma transport: (1 transport based on the parallel ambipolar field, and (2 transport based on the parallel electric field. The results show that the growth rate of the generalized Rayleigh–Taylor instability is not affected by the choice of the potential solution. However, differences are observed in the structures of the irregularities between the 2-D and 3-D solutions. Additionally, the plasma velocity along the geomagnetic field computed using the full 3-D solution shows complex structures that are not captured by the simplified model. This points out that only the full 3-D model is able to fully capture the complex physics of the equatorial F region.

  9. Sensitivity of population smoke exposure to fire locations in Equatorial Asia

    Science.gov (United States)

    Kim, Patrick S.; Jacob, Daniel J.; Mickley, Loretta J.; Koplitz, Shannon N.; Marlier, Miriam E.; DeFries, Ruth S.; Myers, Samuel S.; Chew, Boon Ning; Mao, Yuhao H.

    2015-02-01

    High smoke concentrations in Equatorial Asia, primarily from land conversion to oil palm plantations, affect a densely populated region and represent a serious but poorly quantified air quality concern. Continued expansion of the oil palm industry is expected but the resulting population exposure to smoke is highly dependent on where this expansion takes place. We use the adjoint of the GEOS-Chem chemical transport model to map the sensitivity of smoke concentrations in major Equatorial Asian cities, and for the population-weighted region, to the locations of the fires. We find that fires in southern Sumatra are particularly detrimental, and that a land management policy protecting peatswamp forests in Southeast Sumatra would be of great air quality benefit. Our adjoint sensitivities can be used to immediately infer population exposure to smoke for any future fire emission scenario.

  10. Features of highly structured equatorial plasma irregularities deduced from CHAMP observations

    DEFF Research Database (Denmark)

    Xiong, C.; Luhr, H.; Ma, S. Y.

    2012-01-01

    In this study five years of CHAMP (Challenging Mini-satellite Payload) fluxgate magnetometer (FGM) data is used to investigate the characteristics of Equatorial Plasma Bubbles (EPBs). We filtered the FGM data by using bandpasses with four different cut-off periods to get the EPBs with different...... maximum spatial scale sizes in the meridional plane ranging from 76-608 km. Associated with the EPB observations at about 400km, the typical altitude of CHAMP during the year 2000-2005, we also investigate the postsunset equatorial vertical plasma drift data from ROCSAT1 (Republic of China Satellite 1...... for different scale sizes with the global distribution of plasma vertical uplift, we have found that EPBs reaching higher altitudes are more structured than those which are sampled by CHAMP near the top side of the depleted fluxtube. Such a result is in accord with 3-D model simulations (Aveiro and Hysell, 2010...

  11. Recycled iron fuels new production in the eastern equatorial Pacific Ocean.

    Science.gov (United States)

    Rafter, Patrick A; Sigman, Daniel M; Mackey, Katherine R M

    2017-10-24

    Nitrate persists in eastern equatorial Pacific surface waters because phytoplankton growth fueled by nitrate (new production) is limited by iron. Nitrate isotope measurements provide a new constraint on the controls of surface nitrate concentration in this region and allow us to quantify the degree and temporal variability of nitrate consumption. Here we show that nitrate consumption in these waters cannot be fueled solely by the external supply of iron to these waters, which occurs by upwelling and dust deposition. Rather, a substantial fraction of nitrate consumption must be supported by the recycling of iron within surface waters. Given plausible iron recycling rates, seasonal variability in nitrate concentration on and off the equator can be explained by upwelling rate, with slower upwelling allowing for more cycles of iron regeneration and uptake. The efficiency of iron recycling in the equatorial Pacific implies the evolution of ecosystem-level mechanisms for retaining iron in surface ocean settings where it limits productivity.

  12. Longitudinal, seasonal and solar cycle variation in lunar tide influence on the equatorial electrojet

    International Nuclear Information System (INIS)

    Yizengaw, Endawoke; Carter, Brett A.

    2017-01-01

    It has been well documented that the lunar tidal waves can modulate the ionospheric electrodynamics and create a visible influence on the equatorial electrojet (EEJ). The lunar tide influence gets intensified around noon, primarily during new and full Moon periods. However, the longitudinal, seasonal and solar cycle variability in the lunar tide influence on ionospheric current systems is not well understood yet. In order to investigate this, 17 years (1998-2014) of extensive magnetometer observations at four longitudinal sectors (western American, western and eastern African, and Asian) have been analyzed. All observations performed during magnetically active periods (K p >3) have been excluded for this study to eliminate storm contributions to the geomagnetic field variation at the geomagnetic equator. This study's quantitative analysis revealed significant longitudinal, seasonal and solar cycle dependence of the lunar tide influence on the equatorial electrojet.

  13. A perspective of Middle-Atmosphere Dynamics (MAD) studies at the New International Equatorial Observatory (NIEO)

    Science.gov (United States)

    Yamanaka, M. D.; Fukao, S.

    1989-01-01

    The equatorial region has attracted many MAD studies mainly based on data of limited locations and resolutions. Established at NIEO are: (1) Climatology of the equatorial middle atmosphere (all of the mean zonal flow, the meridional and/or east-west circulations and the planetary/gravity waves are described based on massive, reliable data statistics); (2) Troposphere-stratosphere coupling at the equator (the candidate location of NIEO is just at the stratospheric fountain area where the tracers and waves are pumped up into the middle atmosphere); and (3) Mesosphere-thermosphere coupling at the equator; thermospheric superrotation, which may be caused either by ion drag or by tidal breaking, is examined in detail by observations covering a wide altitude range from the mesosphere through the thermosphere.

  14. Longitudinal, seasonal and solar cycle variation in lunar tide influence on the equatorial electrojet

    Directory of Open Access Journals (Sweden)

    E. Yizengaw

    2017-04-01

    Full Text Available It has been well documented that the lunar tidal waves can modulate the ionospheric electrodynamics and create a visible influence on the equatorial electrojet (EEJ. The lunar tide influence gets intensified around noon, primarily during new and full Moon periods. However, the longitudinal, seasonal and solar cycle variability in the lunar tide influence on ionospheric current systems is not well understood yet. In order to investigate this, 17 years (1998–2014 of extensive magnetometer observations at four longitudinal sectors (western American, western and eastern African, and Asian have been analyzed. All observations performed during magnetically active periods (Kp>3 have been excluded for this study to eliminate storm contributions to the geomagnetic field variation at the geomagnetic equator. This study's quantitative analysis revealed significant longitudinal, seasonal and solar cycle dependence of the lunar tide influence on the equatorial electrojet.

  15. Spatial variability in macroinvertebrate assemblages along and among neighbouring equatorial glacier-fed streams

    DEFF Research Database (Denmark)

    Kuhn, J.; Andino, P.; Calvez, R.

    2011-01-01

    , following a supposed decrease in environmental harshness along the streams. Relationships between faunal metrics and the four environmental variables mean temperature, the stability index, chlorophyll a and coarse particulate organic matter also varied among the three streams. Generalised linear model...... and temperature and stability as main driving factors were met by our three replicate equatorial glacial streams. Qualitative departures from the model were mainly because of zoogeographical differences. We demonstrated that variability in assemblages between comparable sites in closely situated streams...... Andes of Ecuador. Our main goals were (i) to determine overall longitudinal patterns in density, taxon richness and the composition of macroinvertebrate assemblages and driving factors in equatorial glacial streams and (ii) to examine variability among replicate streams in faunal metrics and assemblages...

  16. Global equatorial sea-surface temperatures over the last 150,000 years: An update from foraminiferal elemental analysis

    Digital Repository Service at National Institute of Oceanography (India)

    Saraswat, R.

    Solar insolation changes are amongst various factors that affect sea-surface temperature (SST) which in turn modulate global climate. Out of all the oceanic regions, equatorial region receives the maximum solar insolation and thus is the locale...

  17. Spatial and temporal variability in nutrients and carbon uptake during 2004 and 2005 in the eastern equatorial Pacific Ocean

    DEFF Research Database (Denmark)

    Palacz, A. P.; Chai, F.

    2012-01-01

    The eastern equatorial Pacific plays a great role in the global carbon budget due to its enhanced biological productivity linked to the equatorial upwelling. However, as confirmed by the Equatorial Biocomplexity cruises in 2004 and 2005, nutrient upwelling supply varies strongly, partly due...... and intraseasonal time scales. Here, high resolution Pacific ROMS-CoSiNE (Regional Ocean Modeling System-Carbon, Silicon, Nitrogen Ecosystem) model results were evaluated with in situ and remote sensing data. The results of model-data comparison revealed a good agreement in domain-average hydrographic....... In order to fully resolve the complexity of biological and physical interactions in the eastern equatorial Pacific, we recommended improving CoSiNE and other models by introducing more phytoplankton groups, variable Redfield and carbon to chlorophyll ratios, as well as resolving the Fe-Si co...

  18. Iron bacterial phylogeny and their execution towards iron availability in Equatorial Indian Ocean and Coastal Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Rajasabapathy, R.; Mohandass, C.; VijayRaj, A.S.; Madival, V.V.; Meena, R.M.

    Based on distinct colony morphology, color, size, shape and certain other traits, 92 bacterial isolates were investigated to understand their managerial ability on iron from the Arabian Sea and Equatorial Indian Ocean samples. The ARDRA (amplified r...

  19. {sup 10}Be/{sup 230}Th ratios as proxy for particle flux in the equatorial Pacific ocean

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, R.F.; Fleisher, M.Q. [LDEO of Columbia Univ. (United States); Kubik, P.W. [Paul Scherrer Inst. (PSI), Villigen (Switzerland); Suter, M. [Eidgenoessische Technische Hochschule, Zurich (Switzerland)

    1997-09-01

    Particulate {sup 10}Be/{sup 230}Th ratios collected by sediment traps in the central equatorial Pacific Ocean exhibit a positive correlation with particle flux, but little or no correlation with particle composition. (author) 1 fig., 4 refs.

  20. Equatorial Indian Ocean subsurface current variability in an Ocean General Circulation Model

    Science.gov (United States)

    Gnanaseelan, C.; Deshpande, Aditi

    2018-03-01

    The variability of subsurface currents in the equatorial Indian Ocean is studied using high resolution Ocean General Circulation Model (OGCM) simulations during 1958-2009. February-March eastward equatorial subsurface current (ESC) shows weak variability whereas strong variability is observed in northern summer and fall ESC. An eastward subsurface current with maximum amplitude in the pycnocline is prominent right from summer to winter during strong Indian Ocean Dipole (IOD) years when air-sea coupling is significant. On the other hand during weak IOD years, both the air-sea coupling and the ESC are weak. This strongly suggests the role of ESC on the strength of IOD. The extension of the ESC to the summer months during the strong IOD years strengthens the oceanic response and supports intensification and maintenance of IODs through modulation of air sea coupling. Although the ESC is triggered by equatorial winds, the coupled air-sea interaction associated with IODs strengthens the ESC to persist for several seasons thereby establishing a positive feedback cycle with the surface. This suggests that the ESC plays a significant role in the coupled processes associated with the evolution and intensification of IOD events by cooling the eastern basin and strengthening thermocline-SST (sea surface temperature) interaction. As the impact of IOD events on Indian summer monsoon is significant only during strong IOD years, understanding and monitoring the evolution of ESC during these years is important for summer monsoon forecasting purposes. There is a westward phase propagation of anomalous subsurface currents which persists for a year during strong IOD years, whereas such persistence or phase propagation is not seen during weak IOD years, supporting the close association between ESC and strength of air sea coupling during strong IOD years. In this study we report the processes which strengthen the IOD events and the air sea coupling associated with IOD. It also unravels

  1. Polar and equatorial coronal hole winds at solar minima: From the heliosphere to the inner corona

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, L.; Landi, E., E-mail: lzh@umich.edu [Department of Atmospheric, Oceanic, and Space Sciences, University of Michigan, Ann Arbor, MI 48105 (United States)

    2014-02-01

    Fast solar wind can be accelerated from at least two different sources: polar coronal holes and equatorial coronal holes. Little is known about the relationship between the wind coming from these two different latitudes and whether these two subcategories of fast wind evolve in the same way during the solar cycle. Nineteen years of Ulysses observations, from 1990 to 2009, combined with ACE observations from 1998 to the present provide us with in situ measurements of solar wind properties that span two entire solar cycles. These missions provide an ideal data set to study the properties and evolution of the fast solar wind originating from equatorial and polar holes. In this work, we focus on these two types of fast solar wind during the minima between solar cycles 22 and 23 and 23 and 24. We use data from SWICS, SWOOPS, and VHM/FGM on board Ulysses and SWICS, SWEPAM, and MAG on board ACE to analyze the proton kinetic, thermal, and dynamic characteristics, heavy ion composition, and magnetic field properties of these two fast winds. The comparison shows that: (1) their kinetic, thermal, compositional, and magnetic properties are significantly different at any time during the two minima and (2) they respond differently to the changes in solar activity from cycle 23 to 24. These results indicate that equatorial and polar fast solar wind are two separate subcategories of fast wind. We discuss the implications of these results and relate them to remote-sensing measurements of the properties of polar and equatorial coronal holes carried out in the inner corona during these two solar minima.

  2. Investigation of Jupiter's Equatorial Hotspots and Plumes Using Cassini ISS Observations

    Science.gov (United States)

    Choi, David S.; Showman, A. P.; Vasavada, A. R.; Simon-Miller, A. A.

    2012-01-01

    We present updated analysis of Jupiter's equatorial meteorology from Cassini observations. For two months preceding the spacecraft's closest approach, the ISS onboard regularly imaged the atmosphere. We created time-lapse movies from this period in order to analyze the dynamics of equatorial 5-micron hot spots and their interactions with adjacent latitudes. Hot spots are quasi-stable, rectangular dark areas on visible-wavelength images, with defined eastern edges that sharply contrast with surrounding clouds, but a diffuse western edge serving as a nebulous boundary with adjacent equatorial plumes. Hot spots exhibit significant variations in size and shape over timescales of days and weeks. Some of these changes correspond with passing vortex systems from adjacent latitudes interacting with hot spots. Strong anticyclonic gyres present to the south and southeast of the dark areas appear to circulate into hot spots. Impressive, bright white plumes occupy spaces in between hot spots. Compact cirrus-iike 'scooter' clouds flow rapidly through the plumes before disappearing within the dark areas. This raises the possibility that the plumes and fast-moving clouds are at higher altitudes, because their speed does not match previously published zonal wind profiles. Most profiles represent the drift speed of the hot spots at their latitude from pattern matching of the entire longitudinal image strip. If a downward branch of an equatorially-trapped Rossby waves controls the overall appearance of hot spots, however, the westward phase velocity of the wave leads to underestimates of the true jet stream speed. Instead, our expanded data set demonstrating the rapid flow of these scooter clouds may be more illustrative of the actual jet stream speed at these latitudes. This research was supported by a NASA JDAP grant and the NASA Postdoctoral Program.

  3. Equatorial Oceanic Waves and the Evolution of 2007 Positive Indian Ocean Dipole

    Directory of Open Access Journals (Sweden)

    Iskhaq Iskandar

    2014-01-01

    Full Text Available The role of equatorial oceanic waves on the evolution of the 2007 positive Indian Ocean Dipole (pIOD event was evaluated using available observations and output from a quasi-analytical linear wave model. It was found that the 2007 pIOD event was a weak and short-lived event: developed in the mid-summer (July, matured in the early-fall (September, and terminated in the mid-fall (October. The evolution of the 2007 pIOD event was linked to the equatorial wave dynamics. The event development was associated with the generation of upwelling equatorial Kelvin waves (westward current anomalies generated by easterly wind anomalies. The event termination was associated with the occurrence of eastward zonal current anomalies resulting from a complex interplay between the wind-forced down welling Kelvin waves and the eastern-boundary-reflected Rossby waves. Results from a quasi-analytical linear wave model show that during the event development and maturation, the wind-forced Kelvin waves played a dominant role in generating zonal current anomalies along the equatorial Indian Ocean, while the eastern-boundary-reflected Rossby waves tended to weaken the wind-forced Kelvin wave signals. During the event termination our model shows that the initiation of anomalous eastward current resulted from the reflected Rossby waves at the eastern boundary. The wind-forced Kelvin waves associated with the seasonal reversal of the monsoon further strengthened the eastward zonal currents generated by the boundary-generated Rossby waves in late-October/early-November. This highlights the importance of the eastern-boundary-reflected Rossby waves on the IOD event termination.

  4. Range expansion drives dispersal evolution in an equatorial three-species symbiosis.

    Directory of Open Access Journals (Sweden)

    Guillaume Léotard

    Full Text Available BACKGROUND: Recurrent climatic oscillations have produced dramatic changes in species distributions. This process has been proposed to be a major evolutionary force, shaping many life history traits of species, and to govern global patterns of biodiversity at different scales. During range expansions selection may favor the evolution of higher dispersal, and symbiotic interactions may be affected. It has been argued that a weakness of climate fluctuation-driven range dynamics at equatorial latitudes has facilitated the persistence there of more specialized species and interactions. However, how much the biology and ecology of species is changed by range dynamics has seldom been investigated, particularly in equatorial regions. METHODOLOGY/PRINCIPAL FINDINGS: We studied a three-species symbiosis endemic to coastal equatorial rainforests in Cameroon, where the impact of range dynamics is supposed to be limited, comprised of two species-specific obligate mutualists--an ant-plant and its protective ant--and a species-specific ant parasite of this mutualism. We combined analyses of within-species genetic diversity and of phenotypic variation in a transect at the southern range limit of this ant-plant system. All three species present congruent genetic signatures of recent gradual southward expansion, a result compatible with available regional paleoclimatic data. As predicted, this expansion has been accompanied by the evolution of more dispersive traits in the two ant species. In contrast, we detected no evidence of change in lifetime reproductive strategy in the tree, nor in its investment in food resources provided to its symbiotic ants. CONCLUSIONS/SIGNIFICANCE: Despite the decreasing investment in protective workers and the increasing investment in dispersing females by both the mutualistic and the parasitic ant species, there was no evidence of destabilization of the symbiosis at the colonization front. To our knowledge, we provide here the

  5. Azimuthal directions of equatorial noise propagation determined using 10 years of data from the Cluster spacecraft

    Czech Academy of Sciences Publication Activity Database

    Němec, F.; Santolík, Ondřej; Pickett, J. S.; Hrbáčková, Zuzana; Cornilleau-Wehrlin, N.

    2013-01-01

    Roč. 118, č. 11 (2013), 7160–7169 ISSN 2169-9380 R&D Projects: GA ČR GAP205/10/2279 Institutional support: RVO:68378289 Keywords : equatorial noise * fast magnetosonic waves * fast magnetosonic waves Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 3.440, year: 2013 http://onlinelibrary.wiley.com/doi/10.1002/2013JA019373/abstract

  6. Seasonal cycle of cross-equatorial flow in the central Indian Ocean

    Science.gov (United States)

    Wang, Yi; McPhaden, Michael J.

    2017-05-01

    This study investigates the seasonal cycle of meridional currents in the upper layers of central equatorial Indian Ocean using acoustic Doppler current profiler (ADCP) and other data over the period 2004-2013. The ADCP data set collected along 80.5°E is the most comprehensive collection of direct velocity measurements in the central Indian Ocean to date, providing new insights into the meridional circulation in this region. We find that mean volume transport is southward across the equator in the central Indian Ocean in approximate Sverdrup balance with the wind stress curl. In addition, mean westerly wind stress near the equator drives convergent Ekman flow in the surface layer and subsurface divergent geostrophic flow in the thermocline at 50-150 m depths. In response to a mean northward component of the surface wind stress, the maximum surface layer convergence is shifted off the equator to between 0.5° and 1°N. Evidence is also presented for the existence of a shallow equatorial roll consisting of a northward wind-driven surface drift overlaying the southward directed subsurface Sverdrup transport. Seasonal variations are characterized by cross-equatorial transports flowing from the summer to the winter hemisphere in quasi-steady Sverdrup balance with the wind stress curl. In addition, semiannually varying westerly monsoon transition winds lead to semiannual enhancements of surface layer Ekman convergence and geostrophic divergence in the thermocline. These results quantify expectations from ocean circulation theories for equatorial Indian Ocean meridional circulation patterns with a high degree of confidence given the length of the data records.

  7. Polar and equatorial coronal hole winds at solar minima: From the heliosphere to the inner corona

    International Nuclear Information System (INIS)

    Zhao, L.; Landi, E.

    2014-01-01

    Fast solar wind can be accelerated from at least two different sources: polar coronal holes and equatorial coronal holes. Little is known about the relationship between the wind coming from these two different latitudes and whether these two subcategories of fast wind evolve in the same way during the solar cycle. Nineteen years of Ulysses observations, from 1990 to 2009, combined with ACE observations from 1998 to the present provide us with in situ measurements of solar wind properties that span two entire solar cycles. These missions provide an ideal data set to study the properties and evolution of the fast solar wind originating from equatorial and polar holes. In this work, we focus on these two types of fast solar wind during the minima between solar cycles 22 and 23 and 23 and 24. We use data from SWICS, SWOOPS, and VHM/FGM on board Ulysses and SWICS, SWEPAM, and MAG on board ACE to analyze the proton kinetic, thermal, and dynamic characteristics, heavy ion composition, and magnetic field properties of these two fast winds. The comparison shows that: (1) their kinetic, thermal, compositional, and magnetic properties are significantly different at any time during the two minima and (2) they respond differently to the changes in solar activity from cycle 23 to 24. These results indicate that equatorial and polar fast solar wind are two separate subcategories of fast wind. We discuss the implications of these results and relate them to remote-sensing measurements of the properties of polar and equatorial coronal holes carried out in the inner corona during these two solar minima.

  8. The nonlinear equatorial Kelvin wave. [in coastal currents of El Nino and Gulf of Guinea

    Science.gov (United States)

    Boyd, J. P.

    1980-01-01

    Using the method of strained coordinates, a uniformly valid approximation to the nonlinear equatorial Kelvin wave is derived. It is shown that nonlinear effects are negligible for the Kelvin waves associated with the Gulf of Guinea upwelling. The Kelvin waves involved in El Nino, however, are significantly distorted both in shape and speed. The leading edge is smoothed and expanded rather than steepened, but the trailing edge will form sharp fronts and eventually break.

  9. Deglacial Western Equatorial Pacific pCO2 Reconstruction Using Boron Isotopes of Planktonic Foraminiferas

    Science.gov (United States)

    Kubota, K.; Yokoyama, Y.; Ishikawa, T.; Sagawa, T.; Ikehara, M.; Yamazaki, T.

    2017-12-01

    During the last deglaciation (ca. 19 - 11 ka), partial pressure of CO2 (pCO2) of the atmosphere increased by 80 μatm. Many paleoceanographers point out that the ocean had played an important role in atmospheric CO2 rise, since the ocean have 60 times larger capacity to store carbon compared to the atmosphere. However, evidence on where carbon was transferred from the ocean to the atmosphere is still lacking, hampering our understanding of global carbon cycles in glacial-interglacial timescales. Boron isotope of skeletons of marine calcifying organisms such as corals and foraminiferas can pin down where CO2 source/sink existed, because boron isotopes of marine calcium carbonates is dependent on seawater pH, from which pCO2 of the past seawater can be reconstructed. In previous studies using the boron isotope teqnique, Martinez-Boti et al. (2015, Nature) and Kubota et al. (2014, Scientific Reports) revealed that central and eastern parts of the equatorial Pacific acted as a CO2 source (i.e., CO2 emission) during the last deglaciation, suggesting the equatorial Pacific's contribution to atmospheric CO2 rise. However, some conflicting results have been confirmed in a marine sediment record from the western part of the equatorial Pacific (Palmer & Pearson, 2003, Science), making the conclusion elusive. In this presentation, we will show new results of Mg/Ca, oxygen isotope, and boron isotope measurements during the last 35 ka on two species of surface dwelling foraminiferas (Globigerinoides ruber and G. sacculifer) which was hand-picked separatedly from a well-dated marine sediment core recovered from the West Caroline Basin (KR05-15 PC01) (Yamazaki et al., 2008, GRL). From the new records, we will discuss how the equatorial Pacific behaved during the last deglaciation and how it related to the global carbon cycles.

  10. Longitudinal, seasonal and solar cycle variation in lunar tide influence on the equatorial electrojet

    OpenAIRE

    E. Yizengaw; B. A. Carter

    2017-01-01

    It has been well documented that the lunar tidal waves can modulate the ionospheric electrodynamics and create a visible influence on the equatorial electrojet (EEJ). The lunar tide influence gets intensified around noon, primarily during new and full Moon periods. However, the longitudinal, seasonal and solar cycle variability in the lunar tide influence on ionospheric current systems is not well understood yet. In order to investigate this, 17 years (1998–2014) of extensiv...

  11. Repeated Storage of Respired Carbon in the Equatorial Pacific Ocean Over the Last Three Glacial Cycles

    Science.gov (United States)

    Jacobel, A. W.; McManus, J. F.; Anderson, R. F.; Winckler, G.

    2017-12-01

    As the largest reservoir of carbon actively exchanging with the atmosphere on glacial-interglacial timescales, the deep ocean has been implicated as the likely location of carbon dioxide sequestration during Pleistocene glaciations. Despite strong theoretical underpinnings for this expectation, it has been challenging to identify unequivocal evidence for respired carbon storage in the paleoceanographic record. Data on the rate of ocean ventilation derived from paired planktonic-benthic foraminifera radiocarbon ages conflict across the equatorial Pacific, and different proxy reconstructions contradict one another about the depth and origin of the watermass containing the respired carbon. Because any change in the storage of respiratory carbon must be accompanied by corresponding changes in dissolved oxygen concentrations, proxy data reflecting bottom water oxygenation are of value in addressing these apparent inconsistencies. We present new records of the redox sensitive metal uranium from the central equatorial Pacific to qualitatively identify intervals associated with respiratory carbon storage over the past 350 kyr. Our data reveal periods of deep ocean authigenic uranium deposition in association with each of the last three glacial maxima. Equatorial Pacific export productivity data show intervals with abundant authigenic uranium are not associated with local productivity increases, indicating episodic precipitation of authigenic uranium does not directly reflect increases in situ microbial respiration, but rather occurs in response to basin-wide decreases in deep water oxygen concentrations. We combine our new data with previously published results to propose a picture of glacial carbon storage and equatorial Pacific watermass structure that is internally consistent. We conclude that respired carbon storage in the Pacific was a persistent feature of Pleistocene glaciations.

  12. Propagation of equatorial noise to low altitudes: Decoupling from the magnetosonic mode

    Czech Academy of Sciences Publication Activity Database

    Santolík, Ondřej; Parrot, M.; Němec, F.

    2016-01-01

    Roč. 43, č. 13 (2016), s. 6694-6704 ISSN 0094-8276 R&D Projects: GA ČR(CZ) GA14-31899S; GA MŠk(CZ) LH15304 Institutional support: RVO:68378289 Keywords : equatorial noise * magnetosonic waves * polarization and propagation analysis * ray tracing Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 4.253, year: 2016 http://onlinelibrary.wiley.com/doi/10.1002/2016GL069582/full

  13. Quiet Time Depression of the Equatorial Electrojet and Dynamics of the F-layer Ionosphere

    Science.gov (United States)

    Khadka, S.; Valladares, C. E.; Doherty, P.

    2017-12-01

    The depression of the equatorial electrojet (EEJ) is marked by a westward current due to streaming movement of laterally limited (±3°) charged particles in the ionospheric E region during the day along the magnetic equator. It is a complex low-latitude phenomenon and driven by various sources of electric fields associated with global neutral wind, solar tidal force, Interplanetary magnetic Field (IMF), etc. This unique physical property of the equatorial ionosphere holds a great promise for sorting out the governing mechanism of the dayside ionospheric electrodynamics and the onset of the enigmatic plasma structures in the ionospheric layers. Present study provides an overview of the special sequence of the longitudinal, seasonal, and occurrence rate variability of the depression of the EEJ, including its temporal variation, using data from an excellent chain of magnetic and ionospheric observatories along the low-latitude regions. A case and statistical study of the geomagnetically quiet time depression of EEJ strengths is presented using a pair of magnetometers, one located at the dip equator and another off the dip equator (±6° to ±9° away) in the American low-latitude regions. The significance of the variability of the depression of the EEJ current observed in the scenario of vertical drifts, sporadic E-layer, the equatorial F region plasma fountain, and height of the peak ionization in the F-layer, as well as GPS-TEC distributions, will be investigated.

  14. Assessing and Optimizing Argo profile mapping : An example in the Equatorial Pacific

    Science.gov (United States)

    Gasparin, Florent; Roemmich, Dean; Gilson, John; Sprintall, Janet

    2014-05-01

    Estimation of subsurface temperature, salinity and velocity has been revolutionized over the last decade as a result of development and deployment of the Argo Program. Argo products have become one of the major observational tools in Oceanography, used in a wide range of basic research, operational models, and education applications. To assess the skill of Argo in estimating oceanic conditions at different scales of variability in the Equatorial Pacific, we optimize Argo profile mapping by focusing on the covariance function. Decorrelation scales are discussed as well as impacts of several different interpolation schemes. The optimization is based on three points 1) Functional representation of the Argo sampled covariance, 2) Realism/Accuracy of the mapping errors and 3) Comparison with independent data such as TAO moorings and sea surface height. The last points show that Argo can represent more than 90% of the total TAO variance and around 80% of the intraseasonal TAO variability (between 10 and 100 days) at the Equator. As an illustration of the improvement, we show how Argo profiles can reveal the vertical structure and vertical phase propagation corresponding to the steric height annual cycle. We also discuss how this unique equatorial wave phenomena is modified during El Nino/La Nina events. This work anticipates a field experiment beginning in early 2014 and can be used for assessing and adapting the equatorial observational network.

  15. Equatorial Scintillation Study at Ilorin and Nsukka, Nigeria during Year 2011-2012

    Science.gov (United States)

    Akala, A.

    2017-12-01

    This study presents GNSS scintillations over Ilorin (8.48 oN, 4.54 oE, and mag lat: 1.83oS) and Nsukka (6.84 oN, 7.37 oE, and mag lat: 2.94oS), Nigeria during year 2011-2012. The two stations are located within the inner flank of the equatorial ionization anomaly. Firstly, we investigated the climatology of equatorial scintillations at the two stations. We suppressed multipath effects on the data by imposing a 300 elevation masking on the data. In addition, we investigated scintillation occurrences at the two locations on a satellite-by-satellite basis at varying elevation angles. The source of scintillation records at low-elevation angle is attributed to multipath, while that at high-elevation angle is attributed to ionospheric irregularities. Seasonally, scintillations recorded highest occurrences during March equinox, and the least during June solstice. The trend of scintillations, at both low- and high-elevation angles at the two stations were almost the same. EGNOS satellites signals scintillated at the two locations during the time intervals when GPS satellites signals experienced scintillations. These results could support the development of scintillation models for equatorial Africa, and could also be of benefit to GPS and EGNOS service providers and designers, with a view to providing robust services for GNSS user community in Africa.

  16. On the how latitude scanning photometer signatures of equatorial ionosphere plasma bubbles

    International Nuclear Information System (INIS)

    Abdu, M.A.; Sobral, J.H.A.; Nakamura, Y.

    1985-01-01

    Meridional and east-west scan 6300 (angstrom) night airglow photometer are being extensively used at the low latitude station Cachoeira Paulista (23 0 S 45 0 W, dip latitude 14 0 ), Brazil, for investigation of trans-equatorial ionospheric plasma bubble dynamics. The zonal velocities of the flux aligned plasma bubbles can be determined, in a straingforward way, from the east-west displacement of the airglow intensity valleys observed by the east-west scan photometer. On the other hand, the determination of the other velocity component of the plasma bubble motion (namely, vertical motion in the equatorial plane) has to be based on the meridional propagation of the airglow valleys observed by the meriodinal scan photometer. Such determinatios of the bubbles vertical rise velocity should, however, involved considerations on different bubble parameters such as, for exemple, the phase of the bubble event (whether growth, mature or decay phase), the limited east-west extension, and the often observed westward tilt of the bubble. In this brief report there were condidered in some detail, possible influences of these different factors on the interpretation of low latitude scanning photometer data to infer trans-equatorial plasma bubble dynamics. (author) [pt

  17. Mid-Pliocene equatorial Pacific sea surface temperature reconstruction: a multi-proxy perspective

    Science.gov (United States)

    Dowsett, Harry J.; Robinson, Marci M.

    2009-01-01

    The Mid-Pliocene is the most recent interval of sustained global warmth, which can be used to examine conditions predicted for the near future. An accurate spatial representation of the low-latitude Mid-Pliocene Pacific surface ocean is necessary to understand past climate change in the light of forecasts of future change. Mid-Pliocene sea surface temperature (SST) anomalies show a strong contrast between the western equatorial Pacific (WEP) and eastern equatorial Pacific (EEP) regardless of proxy (faunal, alkenone and Mg/Ca). All WEP sites show small differences from modern mean annual temperature, but all EEP sites show significant positive deviation from present-day temperatures by as much as 4.4°C. Our reconstruction reflects SSTs similar to modern in the WEP, warmer than modern in the EEP and eastward extension of the WEP warm pool. The east-west equatorial Pacific SST gradient is decreased, but the pole to equator gradient does not change appreciably. We find it improbable that increased greenhouse gases (GHG) alone would cause such a heterogeneous warming and more likely that the cause of Mid-Pliocene warmth is a combination of several forcings including both increased meridional heat transport and increased GHG.

  18. Possible ionospheric preconditioning by shear flow leading to equatorial spread F

    Directory of Open Access Journals (Sweden)

    D. L. Hysell

    2005-10-01

    Full Text Available Vertical shear in the zonal plasma drift speed is apparent in incoherent and coherent scatter radar observations of the bottomside F region ionosphere made at Jicamarca from about 1600–2200 LT. The relative importance of the factors controlling the shear, which include competition between the E and F region dynamos as well as vertical currents driven in the E and F regions at the dip equator, is presently unknown. Bottom-type scattering layers arise in strata where the neutral and plasma drifts differ widely, and periodic structuring of irregularities within the layers is telltale of intermediate-scale waves in the bottomside. These precursor waves appear to be able to seed ionospheric interchange instabilities and initiate full-blown equatorial spread F. The seed or precursor waves may be generated by a collisional shear instability. However, assessing the viability of shear instability requires measurements of the same parameters needed to understand shear flow quantitatively - thermospheric neutral wind and off-equatorial conductivity profiles. Keywords. Ionosphere (Equatorial ionosphere; ionospheric irregularities – Space plasma physics (Waves and instabilities

  19. Study of equatorial Kelvin waves using the MST radar and radiosonde observations

    Directory of Open Access Journals (Sweden)

    P. Kishore

    2005-06-01

    Full Text Available In this paper an attempt has been made to study equatorial Kelvin waves using a high power coherent VHF radar located at Gadanki (13.5° N, 79.2° E, a tropical station in the Indian sub-continent. Simultaneous radiosonde observations taken from a nearby meteorological station located in Chennai (13.04° N, 80.17° E were also used to see the coherence in the observed structures. These data sets were analyzed to study the mean winds and equatorial waves in the troposphere and lower stratosphere. Equatorial waves with different periodicities were identified. In the present study, particular attention has been given to the fast Kelvin wave (6.5-day and slow Kelvin wave (16-day. Mean zonal wind structures were similar at both locations. The fast Kelvin wave amplitudes were somewhat similar in both observations and the maximum amplitude is about 8m/s. The phase profiles indicated a slow downward progression. The slow Kelvin wave (16-day amplitudes shown by the radiosonde measurements are a little larger than the radar derived amplitudes. The phase profiles showed downward phase progression and it translates into a vertical wavelength of ~10-12km. The radar and radiosonde derived amplitudes of fast and slow Kelvin waves are larger at altitudes near the tropopause (15-17km, where the mean wind attains westward maximum.

  20. Observations in equatorial anomaly region of total electron content enhancements and depletions

    Directory of Open Access Journals (Sweden)

    N. Dashora

    2005-10-01

    Full Text Available A GSV 4004A GPS receiver has been operational near the crest of the equatorial anomaly at Udaipur, India for some time now. The receiver provides the line-of-sight total electron content (TEC, the phase and amplitude scintillation index, σφ and S4, respectively. This paper presents the first results on the nighttime TEC depletions associated with the equatorial spread F in the Indian zone. The TEC depletions are found to be very well correlated with the increased S4 index. A new feature of low-latitude TEC is also reported, concerning the observation of isolated and localized TEC enhancements in the nighttime low-latitude ionosphere. The TEC enhancements are not correlated with the S4 index. The TEC enhancements have also been observed along with the TEC depletions. The TEC enhancements have been interpreted as the manifestation of the plasma density enhancements reported by Le et al. (2003.

    Keywords. Ionosphere (Equatorial ionosphere; Ionospheric irregularities

  1. Population exposure to hazardous air quality due to the 2015 fires in Equatorial Asia.

    Science.gov (United States)

    Crippa, P; Castruccio, S; Archer-Nicholls, S; Lebron, G B; Kuwata, M; Thota, A; Sumin, S; Butt, E; Wiedinmyer, C; Spracklen, D V

    2016-11-16

    Vegetation and peatland fires cause poor air quality and thousands of premature deaths across densely populated regions in Equatorial Asia. Strong El-Niño and positive Indian Ocean Dipole conditions are associated with an increase in the frequency and intensity of wildfires in Indonesia and Borneo, enhancing population exposure to hazardous concentrations of smoke and air pollutants. Here we investigate the impact on air quality and population exposure of wildfires in Equatorial Asia during Fall 2015, which were the largest over the past two decades. We performed high-resolution simulations using the Weather Research and Forecasting model with Chemistry based on a new fire emission product. The model captures the spatio-temporal variability of extreme pollution episodes relative to space- and ground-based observations and allows for identification of pollution sources and transport over Equatorial Asia. We calculate that high particulate matter concentrations from fires during Fall 2015 were responsible for persistent exposure of 69 million people to unhealthy air quality conditions. Short-term exposure to this pollution may have caused 11,880 (6,153-17,270) excess mortalities. Results from this research provide decision-relevant information to policy makers regarding the impact of land use changes and human driven deforestation on fire frequency and population exposure to degraded air quality.

  2. Survival probability of precipitations and rain attenuation in tropical and equatorial regions

    Science.gov (United States)

    Mohebbi Nia, Masoud; Din, Jafri; Panagopoulos, Athanasios D.; Lam, Hong Yin

    2015-08-01

    This contribution presents a stochastic model useful for the generation of a long-term tropospheric rain attenuation time series for Earth space or a terrestrial radio link in tropical and equatorial heavy rain regions based on the well-known Cox-Ingersoll-Ross model previously employed in research in the fields of finance and economics. This model assumes typical gamma distribution for rain attenuation in heavy rain climatic regions and utilises the temporal dynamic of precipitation collected in equatorial Johor, Malaysia. Different formations of survival probability are also discussed. Furthermore, the correlation between these probabilities and the Markov process is determined, and information on the variance and autocorrelation function of rain events with respect to the particular characteristics of precipitation in this area is presented. The proposed technique proved to preserve the peculiarities of precipitation for an equatorial region and reproduce fairly good statistics of the rain attenuation correlation function that could help to improve the prediction of dynamic characteristics of rain fade events.

  3. Gravity-driven structures and rift basin evolution: Rio Muni Basin, offshore equatorial West Africa

    Energy Technology Data Exchange (ETDEWEB)

    Turner, J.P. [Univ. of Birmingham (United Kingdom)

    1995-08-01

    Offshore Equatorial Guinea, west Africa, gravity-driven nappes, more than 1 km thick and 15 km from head to toe, provide key evidence in reconstructing the late synrift: evolution of this part of the South Atlantic margin basin system. Furthermore, Aptian-Cenomanian carbonate and clastic rocks in the nappes` allochthonous hanging walls are attracting interest as a new exploration play in west Africa. The nappes exhibit a range of geometries that suggest they share many of the same deformation processes as thin-skin thrust and linked extensional fault systems. Not only are these structures significant in their own right, representing a rare example of gravity tectonics in the virtual absence of major halokinesis, but their presence may record an other-wise undetectable process active during the transition from a rift basin to a passive continental margin. A review of Equatorial Guinea in its pre-Atlantic configuration, alongside neighboring basins in Brazil (the Sergipe-Alagoas basin) and Gabon, suggests that gravity gliding was sustained by a relatively steep, westward paleoslope promoted by east-ward offset of the locus of thermal uplift from the rift basin (i.e., a simple shear model of basin formation). In contrast to gravity-driven structures in most postrift settings, the Equatorial Guinea nappes developed at the close of the Aptian-Albian synrift episode in response to a growing bathymetric deep caused by rapid subsidence outpacing restricted sedimentation.

  4. Identification of Cryptosporidium subtype isolates from HIV-seropositive patients in Equatorial Guinea.

    Science.gov (United States)

    Blanco, María A; Montoya, Ana; Iborra, Asunción; Fuentes, Isabel

    2014-09-01

    Cryptosporidium spp. are enteric parasites that infect humans and animals. In immunocompromised patients infection can be fatal. This study was conducted to identify sub-populations of Cryptosporidium hominis and C. parvum isolates from HIV-seropositive patients in Equatorial Guinea. In a previous study conducted in Equatorial Guinea, faecal samples from 171 HIV patients with gastrointestinal symptoms were analyzed. Of these, 13 and 17 were positive for C. hominis and C. parvum, respectively. The isolates were characterized using gp60 gene analysis. The gp60 gene could only be detected in 57% (17/30) of cases (10 C. parvum and 7 C. hominis). Three C. hominis (Ia, Ib and Id) and two C. parvum (IIc and IIe) subtype families were detected, including several subtypes. The study identified a high diversity of Cryptosporidium subtypes, suggesting that anthroponotic transmission plays an important role in the epidemiology of Cryptosporidium spp. in HIV-seropositive patients in Equatorial Guinea. © The Author 2014. Published by Oxford University Press on behalf of Royal Society of Tropical Medicine and Hygiene. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  5. Population exposure to hazardous air quality due to the 2015 fires in Equatorial Asia

    Science.gov (United States)

    Crippa, P.; Castruccio, S.; Archer-Nicholls, S.; Lebron, G. B.; Kuwata, M.; Thota, A.; Sumin, S.; Butt, E.; Wiedinmyer, C.; Spracklen, D. V.

    2016-11-01

    Vegetation and peatland fires cause poor air quality and thousands of premature deaths across densely populated regions in Equatorial Asia. Strong El-Niño and positive Indian Ocean Dipole conditions are associated with an increase in the frequency and intensity of wildfires in Indonesia and Borneo, enhancing population exposure to hazardous concentrations of smoke and air pollutants. Here we investigate the impact on air quality and population exposure of wildfires in Equatorial Asia during Fall 2015, which were the largest over the past two decades. We performed high-resolution simulations using the Weather Research and Forecasting model with Chemistry based on a new fire emission product. The model captures the spatio-temporal variability of extreme pollution episodes relative to space- and ground-based observations and allows for identification of pollution sources and transport over Equatorial Asia. We calculate that high particulate matter concentrations from fires during Fall 2015 were responsible for persistent exposure of 69 million people to unhealthy air quality conditions. Short-term exposure to this pollution may have caused 11,880 (6,153-17,270) excess mortalities. Results from this research provide decision-relevant information to policy makers regarding the impact of land use changes and human driven deforestation on fire frequency and population exposure to degraded air quality.

  6. Differential behaviour of the equatorial ionospheres on the eastern and western coasts of the South American continent

    Energy Technology Data Exchange (ETDEWEB)

    Kane, R.P.

    1981-10-01

    A comparison of the daily variation patterns of the geomagnetic field components H, Z, D and the ionospheric F sub 0 F sub 2, at the equatorial locations Huancayo (12 degrees S, 75 degrees W, dip + 1.9 degrees) on the west coast and Eusebio, Fortaleza (4 degrees S, 39 degrees W, dip - 3.5 degrees) on the east coast of the South American continent, shows that the equatorial electrojet and the associated fountain effect are weaker on the east coast.

  7. Seasonal Migration of Monsoons between the Northern and Southern Hemisphere as Revealed from Equatorially Symmetric and Asymmetric OLR Data

    OpenAIRE

    Jun, MATSUMOTO; Takio, MURAKAMI; Department of Earth and Planetary Science, University of Tokyo; Department of Meteorology, University of Hawaii

    2002-01-01

    The climatological pentad mean OLR data are partitioned into symmetric component OLR', and asymmetric component OLR", with reference to the equator. Objective criteria are then introduced to define the intensity, center and areal extent of strong convections with OLR' (OLR") of less than 220 (-20) Wm^-2 over the equatorial (subtropical) domains, and seasonal migration of monsoons between the two hemispheres is investigated. Over the equatorial continents, such as Africa and South America, OLR...

  8. Theoretical study on mechanism of the photochemical ligand substitution of fac-[Re(I)(bpy)(CO)3(PR3)](+) complex.

    Science.gov (United States)

    Saita, Kenichiro; Harabuchi, Yu; Taketsugu, Tetsuya; Ishitani, Osamu; Maeda, Satoshi

    2016-07-14

    The mechanism of the CO ligand dissociation of fac-[Re(I)(bpy)(CO)3P(OMe)3](+) has theoretically been investigated, as the dominant process of the photochemical ligand substitution (PLS) reactions of fac-[Re(I)(bpy)(CO)3PR3](+), by using the (TD-)DFT method. The PLS reactivity can be determined by the topology of the T1 potential energy surface because the photoexcited complex is able to decay into the T1 state by internal conversions (through conical intersections) and intersystem crossings (via crossing seams) with sufficiently low energy barriers. The T1 state has a character of the metal-to-ligand charge-transfer ((3)MLCT) around the Franck-Condon region, and it changes to the metal-centered ((3)MC) state as the Re-CO bond is elongated and bent. The equatorial CO ligand has a much higher energy barrier to leave than that of the axial CO, so that the axial CO ligand selectively dissociates in the PLS reaction. The single-component artificial force induced reaction (SC-AFIR) search reveals the CO dissociation pathway in photostable fac-[Re(I)(bpy)(CO)3Cl]; however, the dissociation barrier on the T1 state is substantially higher than that in fac-[Re(I)(bpy)(CO)3PR3](+) and the minimum-energy seams of crossings (MESXs) are located before and below the barrier. The MESXs have also been searched in fac-[Re(I)(bpy)(CO)3PR3](+) and no MESXs were found before and below the barrier.

  9. Shutdown dose rates at ITER equatorial ports considering radiation cross-talk from torus cryopump lower port

    Energy Technology Data Exchange (ETDEWEB)

    Juárez, Rafael, E-mail: rjuarez@ind.uned.es [Departamento de Ingeniería Energética, ETSII-UNED, Calle Juan del Rosal 12, Madrid 28040 (Spain); Pampin, Raul [F4E, Torres Diagonal Litoral B3, Josep Pla 2, Barcelona 08019 (Spain); Levesy, Bruno [ITER Organization, 13115 Route de Vinon sur Verdon, St Paul Lez Durance (France); Moro, Fabio [ENEA, Via Enrico Fermi 45, Frascati, Rome (Italy); Suarez, Alejandro [ITER Organization, 13115 Route de Vinon sur Verdon, St Paul Lez Durance (France); Sanz, Javier [Departamento de Ingeniería Energética, ETSII-UNED, Calle Juan del Rosal 12, Madrid 28040 (Spain)

    2015-11-15

    Shutdown dose rates for planned maintenance purposes is an active research field in ITER. In this work the radiation (neutron and gamma) cross-talk between ports in the most conservative case foreseen in ITER is investigated: the presence of a torus cryopump lower port, mostly empty for pumping efficiency reasons. There will be six of those ports: #4, #6, #10, #12, #16 and #18. The equatorial ports placed above them will receive a significant amount of additional radiation affecting the shutdown dose rates during in situ maintenance activities inside the cryostat, and particularly in the port interspace area. In this study a general situation to all the equatorial ports placed above torus cryopump lower ports is considered: a generic diagnostics equatorial port placed above the torus cryopump lower port (LP#4). In terms of shutdown dose rates at equatorial port interspace after 10{sup 6} s of cooling time, 405 μSv/h has been obtained, of which 160 μSv/h (40%) are exclusively due to radiation cross-talk from a torus cryopump lower port. Equatorial port activation due to only “local neutrons” contributes 166 μSv/h at port interspace, showing that radiation cross-talk from such a lower port is a phenomenon comparable in magnitude to the neutron leakage though the equatorial port plug.

  10. Equatorial symmetry of Boussinesq convective solutions in a rotating spherical shell allowing rotation of the inner and outer spheres

    International Nuclear Information System (INIS)

    Kimura, Keiji; Takehiro, Shin-ichi; Yamada, Michio

    2014-01-01

    We investigate properties of convective solutions of the Boussinesq thermal convection in a moderately rotating spherical shell allowing the respective rotation of the inner and outer spheres due to the viscous torque of the fluid. The ratio of the inner and outer radii of the spheres, the Prandtl number, and the Taylor number are fixed to 0.4, 1, and 500 2 , respectively. The Rayleigh number is varied from 2.6 × 10 4 to 3.4 × 10 4 . In this parameter range, the behaviours of obtained asymptotic convective solutions are almost similar to those in the system whose inner and outer spheres are restricted to rotate with the same constant angular velocity, although the difference is found in the transition process to chaotic solutions. The convective solution changes from an equatorially symmetric quasi-periodic one to an equatorially symmetric chaotic one, and further to an equatorially asymmetric chaotic one, as the Rayleigh number is increased. This is in contrast to the transition in the system whose inner and outer spheres are assumed to rotate with the same constant angular velocity, where the convective solution changes from an equatorially symmetric quasi-periodic one, to an equatorially asymmetric quasi-periodic one, and to equatorially asymmetric chaotic one. The inner sphere rotates in the retrograde direction on average in the parameter range; however, it sometimes undergoes the prograde rotation when the convective solution becomes chaotic

  11. Observed Intraseasonal Oceanic Variations in the Eastern Equatorial Indian Ocean and in the Outflow Straits of the Indonesian Throughflow

    Directory of Open Access Journals (Sweden)

    Iskhaq Iskandar

    2010-09-01

    Full Text Available The observed currents in the eastern equatorial Indian Ocean and in the outflow straits of the Indonesian Throughflow (ITF are shown to have significant intraseasonal variations and coherency during January 2004 – November 2006. The wavelet analysis between the eastern equatorial Indian Ocean and the ITF straits demonstrates significant intraseasonal coherency for the observed current at 50m depth. At 150m depth, the intraseasonal coherency only occurs between the observed currents in the eastern equatorial Indian Ocean and in the Lombok and Ombai Straits. On the other hand, at 350m depth the intraseasonal coherency is only found between the eastern equatorial Indian Ocean and the Ombai Strait. This intraseasonal coherency is associated with the wind-forced equatorial Kelvin waves which propagate eastward along the equatorial and coastal wave guides. Near-surface intraseasonal variations are associated with the first baroclinic mode with typical phase speed of 2.91 ± 0.46 m s-1, while the deeper layer intraseasonal variations are associated with the second baroclinic mode with typical phase speed of 1.59 ± 0.18 m s-1. Moreover, the lag correlations between the zonal winds and the observed currents at the ITF straits further demonstrate the source of intraseasonal variations in the ITF.

  12. Epipelagic copepod distributions in the eastern equatorial Pacific during the weak La Niña event of 2001

    Directory of Open Access Journals (Sweden)

    Pritha Tutasi

    2011-07-01

    Full Text Available We determined the distribution and abundance of pelagic copepods in the eastern equatorial Pacific between the coast of Ecuador and the Galapagos Islands under oceanographic conditions associated with the weak La Niña event of 2001. In September-October 2001, negative anomalies of sea surface temperature from this event still remained in the eastern equatorial Pacific, mainly between Ecuador and the Galapagos Islands. The event allowed the incursion of the Humboldt Current farther north and of the Equatorial Undercurrent into the study area, favouring a strong Equatorial Front and upwelling processes. There was evidence of mesoscale eddies in the study area and of the presence of the South Equatorial Current going westward at about 1°N. We identified 107 copepod species and analyzed the distribution of the 10 most abundant ones: Oncaea venusta, Subeucalanus pileatus, S. crassus, S. subtenuis, Paraeucalanus attenuatus, Pleuromamma borealis, Scolecithrix danae, Clausocalanus farrani, Temora discaudata and Calanus chilensis. Copepod distribution and abundance exhibited marked latitudinal differences related to the oceanographic conditions; abundance was highest to the southeast of the Galapagos Islands. Oncaea venusta, Pleuromamma borealis, Calanus chilensis, and Subeucalanus subtenuis were the species that best defined the Equatorial Front and the upwelling process.

  13. Correcting ligands, metabolites, and pathways

    Directory of Open Access Journals (Sweden)

    Vriend Gert

    2006-11-01

    Full Text Available Abstract Background A wide range of research areas in bioinformatics, molecular biology and medicinal chemistry require precise chemical structure information about molecules and reactions, e.g. drug design, ligand docking, metabolic network reconstruction, and systems biology. Most available databases, however, treat chemical structures more as illustrations than as a datafield in its own right. Lack of chemical accuracy impedes progress in the areas mentioned above. We present a database of metabolites called BioMeta that augments the existing pathway databases by explicitly assessing the validity, correctness, and completeness of chemical structure and reaction information. Description The main bulk of the data in BioMeta were obtained from the KEGG Ligand database. We developed a tool for chemical structure validation which assesses the chemical validity and stereochemical completeness of a molecule description. The validation tool was used to examine the compounds in BioMeta, showing that a relatively small number of compounds had an incorrect constitution (connectivity only, not considering stereochemistry and that a considerable number (about one third had incomplete or even incorrect stereochemistry. We made a large effort to correct the errors and to complete the structural descriptions. A total of 1468 structures were corrected and/or completed. We also established the reaction balance of the reactions in BioMeta and corrected 55% of the unbalanced (stoichiometrically incorrect reactions in an automatic procedure. The BioMeta database was implemented in PostgreSQL and provided with a web-based interface. Conclusion We demonstrate that the validation of metabolite structures and reactions is a feasible and worthwhile undertaking, and that the validation results can be used to trigger corrections and improvements to BioMeta, our metabolite database. BioMeta provides some tools for rational drug design, reaction searches, and

  14. Autocrine signal transmission with extracellular ligand degradation

    International Nuclear Information System (INIS)

    Muratov, C B; Posta, F; Shvartsman, S Y

    2009-01-01

    Traveling waves of cell signaling in epithelial layers orchestrate a number of important processes in developing and adult tissues. These waves can be mediated by positive feedback autocrine loops, a mode of cell signaling where binding of a diffusible extracellular ligand to a cell surface receptor can lead to further ligand release. We formulate and analyze a biophysical model that accounts for ligand-induced ligand release, extracellular ligand diffusion and ligand–receptor interaction. We focus on the case when the main mode for ligand degradation is extracellular and analyze the problem with the sharp threshold positive feedback nonlinearity. We derive expressions that link the speed of propagation and other characteristics of traveling waves to the parameters of the biophysical processes, such as diffusion rates, receptor expression level, etc. Analyzing the derived expressions we found that traveling waves in such systems can exhibit a number of unusual properties, e.g. non-monotonic dependence of the speed of propagation on ligand diffusivity. Our results for the fully developed traveling fronts can be used to analyze wave initiation from localized perturbations, a scenario that frequently arises in the in vitro models of epithelial wound healing, and guide future modeling studies of cell communication in epithelial layers

  15. Chemistry of marine ligands and siderophores.

    Science.gov (United States)

    Vraspir, Julia M; Butler, Alison

    2009-01-01

    Marine microorganisms are presented with unique challenges to obtain essential metal ions required to survive and thrive in the ocean. The production of organic ligands to complex transition metal ions is one strategy to both facilitate uptake of specific metals, such as iron, and to mitigate the potential toxic effects of other metal ions, such as copper. A number of important trace metal ions are complexed by organic ligands in seawater, including iron, cobalt, nickel, copper, zinc, and cadmium, thus defining the speciation of these metal ions in the ocean. In the case of iron, siderophores have been identified and structurally characterized. Siderophores are low molecular weight iron-binding ligands produced by marine bacteria. Although progress has been made toward the identity of in situ iron-binding ligands, few compounds have been identified that coordinate the other trace metals. Deciphering the chemical structures and production stimuli of naturally produced organic ligands and the organisms they come from is fundamental to understanding metal speciation and bioavailability. The current evidence for marine ligands, with an emphasis on siderophores, and discussion of the importance and implications of metal-binding ligands in controlling metal speciation and cycling within the world's oceans are presented.

  16. Shutdown dose rate analysis of European test blanket modules shields in ITER Equatorial Port #16

    Energy Technology Data Exchange (ETDEWEB)

    Juárez, Rafael, E-mail: rjuarez@ind.uned.es [Departamento de Ingeniería Energética, ETSII-UNED, Calle Juan del Rosal 12, Madrid 28040 (Spain); Sauvan, Patrick; Perez, Lucia [Departamento de Ingeniería Energética, ETSII-UNED, Calle Juan del Rosal 12, Madrid 28040 (Spain); Panayotov, Dobromir; Vallory, Joelle; Zmitko, Milan; Poitevin, Yves [Fusion for Energy (F4E), Torres Diagonal Litoral B3, Josep Pla 2, Barcelona 08019 (Spain); Sanz, Javier [Departamento de Ingeniería Energética, ETSII-UNED, Calle Juan del Rosal 12, Madrid 28040 (Spain)

    2016-11-01

    Highlights: • Nuclear analysis for European TBMs and shields, in ITER Equatorial Port #16, has been conducted in support of the ‘Concept Design Review’ from ITER. • The objective of the work is the characterization of the Shutdown Dose Rates at Equatorial Port #16 interspace. • The role played by the TBM and TBM shields, the equatorial port gaps and the vacuum vessel permeation, in terms of neutron flux transmission is assessed. • The role played by the TBM, TBM shields, Port Plug Frame, Pipe Forest and the machine in terms of activation is also investigated. - Abstract: ‘Fusion for Energy’ (F4E) is designing, developing, and implementing the European Helium-Cooled Lead-Lithium (HCLL) and Helium-Cooled Pebble-Bed (HCPB) Test Blanket Systems (TBSs) for ITER (Nuclear Facility INB-174). An essential element of the Conceptual Design Review (CDR) of these TBSs is the demonstration of capability of Test Blanket Modules (TBM) and their shields to fulfil their function and comply with the design requirements. One of the TBM shields highly relevant design aspects is the project target for shutdown dose rates (SDDR) in the interspace. We investigated two functions of the TBMs and TBM shields—the neutron flux attenuation along the shields, and the reduction of the activation of the components contributing to SDDR. It is shown that TBMs and TBM shields reduce significantly the neutron flux in the port plug (PP). In terms of neutron flux attenuation, the TBM shield provides sufficient neutron flux reduction, being responsible for 5 × 10{sup 6} n/cm{sup 2} s at port interspace, while the EPP gaps and BSM gaps are responsible for 5 × 10{sup 7} n/cm{sup 2} s each. When considering closed upper, lower and lateral neighbour equatorial ports (thus, excluding the cross-talk between ports), a SDDR of 121 μSv/h averaged near the port closure flange was obtained, out of which, only 4 μSv/h are due to the activation of TBMs and TBM shields. Maximum SDDR in the range

  17. Redox Conditions and Related Color Change in Eastern Equatorial Pacific Sediments: IODP Site U1334

    Science.gov (United States)

    Kordesch, W. E.; Gussone, N. C.; Hathorne, E. C.; Kimoto, K.; Delaney, M. L.

    2011-12-01

    This study was prompted by a 65 m thick brown-green color change in deep-sea sediments of IODP Site U1334 (0-38 Ma, 4799 m water depth) that corresponds to its equatorial crossing (caused by the Northward movement of the pacific plate). Green sediment is a visual indicator of reducing conditions in sediment due to enhanced organic matter deposition and burial. Here we use geochemical redox indicators to characterize the effect of equatorial upwelling on bottom water. The modern redox signal is captured in porewater profiles (nitrate, manganese, iron, sulfate) while trace metal Enrichment Factors (EF) in bulk sediment (manganese, uranium, molybdenum, rhenium) normalized to the detrital component (titanium) record redox state at burial. To measure export productivity we also measure biogenic barium. Porewater profiles reveal suboxic diagenesis; profiles follow the expected sequence of nitrate, manganese oxide, and iron oxide reduction with increasing depth. Constant sulfate (~28 μM) implies anoxia has not occurred. Bulk sediment Mn EF are enriched (EF > 1) throughout the record (Mn EF = 15-200) while U and Mo enrichment corresponds to green color and equatorial proximity (U EF = 4-19; Mo EF = 0-7). Constant Mn enrichment implies continuous oxygenation. Uranium and Mo enrichment near the equator represents suboxic conditions also seen in the porewater. Low Re concentrations (below detection) provide additional evidence against anoxia. A comparison of Mn EF from total digestions to samples treated with an additional reductive cleaning step distinguishes between Mn-oxides and Mn-carbonates, indicating oxygenated and reducing conditions respectively. Mn-carbonate occurrence agrees with U and Mo EF; conditions were more reducing near the equator. Bio-Ba shows significant variability over this interval (22-99 mmol g-1). Our geochemical results indicate that bottom waters became suboxic at the equator as a result of equatorial upwelling-influenced increases in organic

  18. Radiation induced ligand loss from cobalt complexes

    International Nuclear Information System (INIS)

    Funston, A. M.; McFadyen, W.D.; Tregloan, P.A.

    2000-01-01

    Full text: Due to the rapid nature of ligand dissociation from cobalt(II) complexes the study of the rate of ligand dissociation necessitates the use of a technique such as pulse radiolysis. This allows the rapid reduction of the corresponding cobalt(III) complex by a reducing radical, such as the aquated electron, to form the cobalt(II) complex. However, to date, no systematic study of either the mechanism of reduction or the influence of the electronic structure on the rate of ligand dissociation has been carried out. In order to understand these processes more fully the mechanism of reduction of a range of related cobalt(III) complexes by the aquated electron and the subsequent rate of ligand dissociation from the resulting cobalt(II) complexes is being investigated. It has been found that a number of processes are observed following the initial rapid reaction of the cobalt(III) complex with the aquated electron. Ultimately ligand loss is observed. Depending upon the complex, the initial processes observed may include the formation of coordinated radicals and electron transfer within the complex. For complexes containing aromatic ligands such as 2,2'-bipyridine, 1,10-phenanthroline and dipyrido[3,2-a:2',3'-c]phenazine the formation of a coordinated radical is observed as the initial reduction step. The kinetics of ligand dissociation of these complexes has been determined. The loss of monodentate ligands is fast and has been indistinguishable from the reduction processes when aromatic ligands are also present in the complex. However, for diamine chelates and diimine chelates spectra of the transient species can be resolved

  19. Stabilization of enzyme by using hydrophobic ligands

    Energy Technology Data Exchange (ETDEWEB)

    Ota, H.; Yamahara, K.; Kuboi, R. [Osaka University, Osaka (Japan)

    1998-02-01

    The protection (stabilization) effect of various hydrophobic ligands on the denaturation and aggregation of carbonic anhydrase from bovine (CAB) has been quantitatively investigated under various heat stress conditions. In a limited temperature range (40-60degC), where the protein was only partially denatured and the local hydrophobicities (LH) of CAB were positive effective stabilization of the protein is achieved by the addition of various ligands. The importance of balance between hydrophobic head and hydrophilic tail of the ligands is hypothesized. 18 refs., 5 figs.

  20. A versatile dinucleating ligand containing sulfonamide groups

    DEFF Research Database (Denmark)

    Sundberg, Jonas; Witt, Hannes; Cameron, Lisa

    2014-01-01

    ligand can be prepared in aqueous solutions using only divalent metal ions. Two of the copper(II) complexes, [Cu2(psmp)(OH)] and [Cu2(psmp)(OAc)2]-, demonstrate the anticipated 1:2 ligand/metal stoichiometry and show that the dimetallic binding site created for exogenous ligands possesses high inherent...... of antiferromagnetic coupling. This is corroborated computationally by broken-symmetry density functional theory, which for isotropic modeling of the coupling predicts an antiferromagnetic coupling strength of J = 70.5 cm-1....

  1. Effect of Ligand Exchange on the Photoluminescence Properties of Cu-Doped Zn-In-Se Quantum Dots

    Science.gov (United States)

    Dong, Xiaofei; Xu, Jianping; Yang, Hui; Zhang, Xiaosong; Mo, Zhaojun; Shi, Shaobo; Li, Lan; Yin, Shougen

    2018-04-01

    The surface-bound ligands of a semiconductor nanocrystal can affect its electron transition behavior. We investigate the photoluminescence (PL) properties of Cu-doped Zn-In-Se quantum dots (QDs) through the exchange of oleylamine with 6-mercaptohexanol (MCH). Fourier transform infrared and 1H nuclear magnetic resonance spectroscopies, and mass spectrometry reveal that the short-chain MCH molecules are bound to the QD surface. The emission peaks remain unchanged after ligand exchange, and the PL quantum yield is reduced from 49% to 38%. The effects of particle size and defect type on the change in PL behavior upon ligand substitution are excluded through high-resolution transmission electron microscopy, UV-Vis absorption, and PL spectroscopies. The origin of the decreased PL intensity is associated with increased ligand density and the stronger ligand electron-donating abilities of MCH-capped QDs that induce an increase in the nonradiative transition probability. A lower PL quenching transition temperature is observed for MCH-capped QDs and is associated with increasing electron-acoustic phonon coupling due to the lower melting temperature of MCH.

  2. Controlling Signal Transduction with Synthetic Ligands

    Science.gov (United States)

    Spencer, David M.; Wandless, Thomas J.; Schreiber, Stuart L.; Crabtree, Gerald R.

    1993-11-01

    Dimerization and oligomerization are general biological control mechanisms contributing to the activation of cell membrane receptors, transcription factors, vesicle fusion proteins, and other classes of intra- and extracellular proteins. Cell permeable, synthetic ligands were devised that can be used to control the intracellular oligomerization of specific proteins. To demonstrate their utility, these ligands were used to reduce intracellular oligomerization of cell surface receptors that lacked their transmembrane and extracellular regions but contained intracellular signaling domains. Addition of these ligands to cells in culture resulted in signal transmission and specific target gene activation. Monomeric forms of the ligands blocked the pathway. This method of ligandregulated activation and termination of signaling pathways has the potential to be applied wherever precise control of a signal transduction pathway is desired.

  3. Allyl functionalized phosphinite and phosphonite ligands: Synthesis ...

    Indian Academy of Sciences (India)

    Allyl functionalized phosphinite and phosphonite ligands: Synthesis, transition metal chemistry and orthopalladation reactions. SINGAPPAGUDEM GOVINDARAJUa, GUDDEKOPPA S ANANTHNAGa, SUSMITA NAIKa,. SHAIKH M MOBINb and MARAVANJI S BALAKRISHNAa,∗. aPhosphorus Laboratory, Department of ...

  4. Organometallic chemistry of chiral diphosphazane ligands ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Chemical Sciences; Volume 114; Issue 4. Organometallic chemistry of chiral diphosphazane ligands: Synthesis and structural characterisation. Kannan Raghuraman Swadhin K Mandal T S Venkatakrishnan Setharampattu S Krishnamurthy Munirathinam Nethaji. Volume 114 Issue 4 August 2002 ...

  5. EGFR Activation by Spatially Restricted Ligands

    National Research Council Canada - National Science Library

    Clouse, Katherine N; Goodrich, Jennifer S

    2006-01-01

    ...) activity has been associated with an increased prognosis of breast cancer. During cogenesis in Drosophila melanogaster local Egfr activation by the spatially-restricted TGFalpha-like ligand Gurken (Grk...

  6. EGFR Activation by Spatially Restricted Ligands

    National Research Council Canada - National Science Library

    Goodrich, Jennifer S

    2005-01-01

    ...) activity has been associated with an increased prognosis of breast cancer. During oogenesis in Drosophila melanogaster, local EGFR activation by the spatially restricted TGF alpha-like ligand, Gurken (Grk...

  7. Chemistry of Marine Ligands and Siderophores

    OpenAIRE

    Vraspir, Julia M.; Butler, Alison

    2009-01-01

    Marine microorganisms are presented with unique challenges to obtain essential metal ions required to survive and thrive in the ocean. The production of organic ligands to complex transition metal ions is one strategy to both facilitate uptake of specific metals, such as iron, and to mitigate the potential toxic effects of other metal ions, such as copper. A number of important trace metal ions are complexed by organic ligands in seawater, including iron, cobalt, nickel, copper, zinc, and cad...

  8. Mixed-ligand copper(ii) Schiff base complexes: the role of the co-ligand in DNA binding, DNA cleavage, protein binding and cytotoxicity.

    Science.gov (United States)

    Lian, Wen-Jing; Wang, Xin-Tian; Xie, Cheng-Zhi; Tian, He; Song, Xue-Qing; Pan, He-Ting; Qiao, Xin; Xu, Jing-Yuan

    2016-05-31

    Four novel mononuclear Schiff base copper(ii) complexes, namely, [Cu(L)(OAc)]·H2O (), [Cu(HL)(C2O4)(EtOH)]·EtOH (), [Cu(L)(Bza)] () and [Cu(L)(Sal)] () (HL = 1-(((2-((2-hydroxypropyl)amino)ethyl)imino)methyl)naphthalene-2-ol), Bza = benzoic acid, Sal = salicylic acid), were synthesized and characterized by X-ray crystallography, elemental analysis and infrared spectroscopy. Single-crystal diffraction analysis revealed that all the complexes were mononuclear molecules, in which the Schiff base ligand exhibited different coordination modes and conformations. The N-HO and O-HO inter- and intramolecular hydrogen bonding interactions linked these molecules into multidimensional networks. Their interactions with calf thymus DNA (CT-DNA) were investigated by UV-visible and fluorescence spectrometry, as well as by viscosity measurements. The magnitude of the Kapp values of the four complexes was 10(5), indicating a moderate intercalative binding mode between the complexes and DNA. Electrophoresis results showed that all these complexes induced double strand breaks of pUC19 plasmid DNA in the presence of H2O2 through an oxidative pathway. In addition, the fluorescence spectrum of human serum albumin (HSA) with the complexes suggested that the quenching mechanism of HSA by the complexes was a static process. Moreover, the antiproliferative activity of the four complexes against HeLa (human cervical carcinoma) and HepG-2 (human liver hepatocellular carcinoma) cells evaluated by colorimetric cell proliferation assay and clonogenic assay revealed that all four complexes had improved cytotoxicity against cancer cells. Inspiringly, complex , with salicylic acid as the auxiliary ligand, displayed a stronger anticancer activity, suggesting that a synergistic effect of the Schiff base complex and the nonsteroidal anti-inflammatory drug may be involved in the cell killing process. The biological features of mixed-ligand copper(ii) Schiff base complexes and how acetic auxiliary

  9. Development of intermediate-scale structure at different altitudes within an equatorial plasma bubble: Implications for L-band scintillations

    Science.gov (United States)

    Bhattacharyya, A.; Kakad, B.; Gurram, P.; Sripathi, S.; Sunda, S.

    2017-01-01

    An important aspect of the development of intermediate-scale length (approximately hundred meters to few kilometers) irregularities in an equatorial plasma bubble (EPB) that has not been considered in the schemes to predict the occurrence pattern of L-band scintillations in low-latitude regions is how these structures develop at different heights within an EPB as it rises in the postsunset equatorial ionosphere due to the growth of the Rayleigh-Taylor instability. Irregularities at different heights over the dip equator map to different latitudes, and their spectrum as well as the background electron density determine the strength of L-band scintillations at different latitudes. In this paper, VHF and L-band scintillations recorded at different latitudes together with theoretical modeling of the scintillations are used to study the implications of this structuring of EPBs on the occurrence and strength of L-band scintillations at different latitudes. Theoretical modeling shows that while S4 index for scintillations on a VHF signal recorded at an equatorial station may be >1, S4 index for scintillations on a VHF signal recorded near the crest of the equatorial ionization anomaly (EIA) generally does not exceed the value of 1 because the intermediate-scale irregularity spectrum at F layer peak near the EIA crest is shallower than that found in the equatorial F layer peak. This also explains the latitudinal distribution of L-band scintillations. Thus, it is concluded that there is greater structuring of an EPB on the topside of the equatorial F region than near the equatorial F layer peak.

  10. The Direct Response in the Equatorial Pacific to the 11 year Solar Cycle Forcing and its mechanisms

    Science.gov (United States)

    Huo, Wenjuan; Xiao, Ziniu

    2017-04-01

    The equatorial Pacific response to 11-year solar cycle is assessed in observation and ensemble historical-Nat simulations from the Coupled Model Intercomparison Project, Phase 5 (CMIP5). We find the central equatorial Pacific is sensitive to the solar forcing. A significant positive correlation is found between observed sea surface temperature (SST) anomaly and sunspot number (SSN) index with a lag of 2 years in the central Pacific. The 11-year solar signal particularly exits in the SST and zonal wind anomalies from spectrum analysis. Based on composite analysis, a warming response appears in the central Pacific with lagging the solar cycle by 1-2 years in observation, and 2-3 years in simulation results. Associated with the ocean temperature anomaly, an anomalous twin Walker circulation cells arise in the equatorial Pacific with their updraft branch centered over the central equatorial Pacific, which is significantly both in observation and simulation. Mixed layer heat budget analysis shows that the atmosphere radiation fluxes modulated by the amounts of cloud cover are responsible for the warming response pattern in the central Pacific. There is a significant positive correlation between the meridional gradient of cloud cover (Δα, Subtropics-Tropic) and zonal SST gradient (ΔT, east-west) in the equatorial Pacific. The warming response in the central equatorial Pacific is amplified by the coupled atmosphere and ocean processes. On the one hand, owing to the zonal SST gradient decreasing in the western and central Pacific but increasing in the eastern and central Pacific, anomalous zonal wind convergence appears in the central Pacific in the three years following the solar peak. The ocean heat transport effect is negative in the central equatorial Pacific, more warm water accumulates locally. On the other hand, anomalous ascending motion over the central Pacific increases the high cloud amount and lets more shortwave radiation come into surface, which combined

  11. Designer TGFβ superfamily ligands with diversified functionality.

    Directory of Open Access Journals (Sweden)

    George P Allendorph

    Full Text Available Transforming Growth Factor--beta (TGFβ superfamily ligands, including Activins, Growth and Differentiation Factors (GDFs, and Bone Morphogenetic Proteins (BMPs, are excellent targets for protein-based therapeutics because of their pervasiveness in numerous developmental and cellular processes. We developed a strategy termed RASCH (Random Assembly of Segmental Chimera and Heteromer, to engineer chemically-refoldable TGFβ superfamily ligands with unique signaling properties. One of these engineered ligands, AB208, created from Activin-βA and BMP-2 sequences, exhibits the refolding characteristics of BMP-2 while possessing Activin-like signaling attributes. Further, we find several additional ligands, AB204, AB211, and AB215, which initiate the intracellular Smad1-mediated signaling pathways more strongly than BMP-2 but show no sensitivity to the natural BMP antagonist Noggin unlike natural BMP-2. In another design, incorporation of a short N-terminal segment from BMP-2 was sufficient to enable chemical refolding of BMP-9, without which was never produced nor refolded. Our studies show that the RASCH strategy enables us to expand the functional repertoire of TGFβ superfamily ligands through development of novel chimeric TGFβ ligands with diverse biological and clinical values.

  12. Exploiting ligand-protein conjugates to monitor ligand-receptor interactions.

    Directory of Open Access Journals (Sweden)

    Hirohito Haruki

    Full Text Available We introduce three assays for analyzing ligand-receptor interactions based on the specific conjugation of ligands to SNAP-tag fusion proteins. Conjugation of ligands to different SNAP-tag fusions permits the validation of suspected interactions in cell extracts and fixed cells as well as the establishment of high-throughput assays. The different assays allow the analysis of strong and weak interactions. Conversion of ligands into SNAP-tag substrates thus provides access to a powerful toolbox for the analysis of their interactions with proteins.

  13. Li+-ligand binding energies and the effect of ligand fluorination on the binding energies

    Science.gov (United States)

    Bauschlicher, Charles W.

    2018-02-01

    The Li+-ligand binding energies are computed for seven ligands and their perfluoro analogs using Density Functional Theory. The bonding is mostly electrostatic in origin. Thus the size of the binding energy tends to correlate with the ligand dipole moment, however, the charge-induced dipole contribution can be sufficiently large to affect the dipole-binding energy correlation. The perfluoro species are significantly less strongly bound than their parents, because the electron withdrawing power of the fluorine reduces the ligand dipole moment.

  14. LigandRFs: random forest ensemble to identify ligand-binding residues from sequence information alone

    KAUST Repository

    Chen, Peng

    2014-12-03

    Background Protein-ligand binding is important for some proteins to perform their functions. Protein-ligand binding sites are the residues of proteins that physically bind to ligands. Despite of the recent advances in computational prediction for protein-ligand binding sites, the state-of-the-art methods search for similar, known structures of the query and predict the binding sites based on the solved structures. However, such structural information is not commonly available. Results In this paper, we propose a sequence-based approach to identify protein-ligand binding residues. We propose a combination technique to reduce the effects of different sliding residue windows in the process of encoding input feature vectors. Moreover, due to the highly imbalanced samples between the ligand-binding sites and non ligand-binding sites, we construct several balanced data sets, for each of which a random forest (RF)-based classifier is trained. The ensemble of these RF classifiers forms a sequence-based protein-ligand binding site predictor. Conclusions Experimental results on CASP9 and CASP8 data sets demonstrate that our method compares favorably with the state-of-the-art protein-ligand binding site prediction methods.

  15. Template synthesis of two new supramolecular zinc(II) complexes containing pentadentate N3O2 semicarbazone ligand: Nanostructure synthesis, Hirshfeld surface analysis, and DFT studies

    Science.gov (United States)

    Tyula, Yunes Abbasi; Zabardasti, Abedien; Goudarziafshar, Hamid; Roudsari, Majid Sadeghi; Dusek, Michal; Eigner, Vaclav

    2017-12-01

    Two new zinc(II) complexes, [Zn(H2dapsc) (CH3OH)2][ZnBr2Cl2] (1) and [Zn(H2dapsc) (CH3OH)Br]Br.(CH3OH) (2), where H2dapsc is 2,6-diacetylpyridine bis(semicarbazone), were synthesized using a template method in which the pentadentate N3O2 semicarbazone ligand derived from [1 + 2] condensation of 2,6-diacetylpyridine and semicarbazide in the presence of zinc(II) ion as template agent. These compounds were characterized by IR spectroscopy, elemental analysis, and single-crystal X-ray diffraction. Their single crystal X-ray structures showed that in both complex cations, the metal center has a distorted pentagonal-bipyramidal geometry in which the semicarbazone (H2dapsc) ligand occupies the equatorial plane, while the axial positions occupy by two methanol ligands in (1) and two bromo and methanol ligands in (2). Furthermore, the impact of the close intermolecular contacts on the crystal packing of (1) and (2) have been further studied using Hirshfeld surface analysis. Density Functional Theory (DFT) method was applied for the calculation of HOMO-LUMO energy gap, atomic charges and vibrational frequencies of title complexes. Moreover, the nanostructure of zinc complex was synthesized by a sonochemical method and characterized by scanning electron microscopy (SEM), X-ray powder diffraction (XRPD), FT-IR spectroscopy, and elemental analysis.

  16. Synthesis and characterization of mixed ligand chiral nanoclusters

    KAUST Repository

    Guven, Zekiye P.

    2016-06-22

    Chiral mixed ligand silver nanoclusters were synthesized in the presence of a chiral and an achiral ligand. While the chiral ligand led mostly to the formation of nanoparticles, the presence of the achiral ligand drastically increased the yield of nanoclusters with enhanced chiral properties. © 2016 The Royal Society of Chemistry.

  17. OH Airglow and Equatorial Variations Observed by ISUAL Instrument on Board the FORMOSAT 2 Satellite

    Directory of Open Access Journals (Sweden)

    Jan-Bai Nee

    2010-01-01

    Full Text Available OH airglow observed by the ISUAL (Imager of Sprites and Upper Atmospheric Lightning instrument on board the FORMOSAT 2 satellite is reported in this paper. The satellite is sun-synchronous and it returns to the same orbit at the same local time daily. By using this property, we can study the upper atmosphere in detail. With a CCD camera, ISUAL has measured the emission layers of OH Meinel band at 630 nm for several two-week periods in 2004 and 2007 in equatorial regions. ISUAL images are snapshots of the atmosphere 250 km (height ¡_ 1200 km (horizontal distance. These images of OH airglow are analyzed to derive its peak height and latitudinal variations. ISUAL observation is unique in its capability of continuous observation of the upper atmosphere as the satellite travels from south to north along a specific orbit. However, 630 nm filter also measured O(1D at 200 km, and there are interferences between O(1D and OH airglows as as observed from a distance in space. We have studied the overlap of two airglows by simulations, and our final analyses show that OH airglow can be correctly derived with its average peak height of 89 ¡_ 2.1 km usually lying within ¡_10¢X latitude about the equator. ISUAL data reveal detailed structures of equatorial OH airglow such as the existences of a few secondary maxima within the equatorial regions, and the oscillations of the peak latitudes. These results are discussed and compared with previous reports.

  18. Self-reported adherence to antiretroviral therapy in HIV+ population from Bata, Equatorial Guinea.

    Science.gov (United States)

    Salmanton-García, Jon; Herrador, Zaida; Ruiz-Seco, Pilar; Nzang-Esono, Jesús; Bendomo, Veronica; Bashmakovic, Emma; Nseng-Nchama, Gloria; Benito, Agustín; Aparicio, Pilar

    2016-01-01

    The human immunodeficiency virus (HIV) and the acquired immune deficiency syndrome (AIDS) represent a serious public health problem in Equatorial Guinea, with a prevalence of 6.2% among adults. the high-activity antiretroviral treatment (HAART) coverage data is 10 points below the overall estimate for Sub-Saharan Africa, and only 61% patients continue with HAART 12 months after it started. This study aims to assess HAART adherence and related factors in Litoral Province of Equatorial Guinea. In this cross-sectional study, socio-demographic and clinical data were collected at Regional Hospital of Bata, during June-July 2014. Adherence to treatment was assessed by using the Spanish version of CEAT-VIH. Bivariate and linear regression analyses were employed to assess HAART adherence-related factors. We interviewed 50 men (35.5%) and 91 women (64.5%), with a mean age of 47.7 ± 8.9 and 36.2 ± 11.2, respectively (p VIH score varied by ethnic group (p = .005). There was a positive correlation between CEAT-VIH score and current CD4 T-cells count (p = .013). The Cronbach's α value was 0.52. To our knowledge, this is the first study to assess HAART adherence in Equatorial Guinea. Internal reliability for CEAT-VIH was low, nonetheless the positive correlation between the CEAT-VIH score and the immunological status of patients add value to our findings. Our results serve as baseline for future research and will also assist stakeholders in planning and undertaking contextual and evidence-based policy initiatives.

  19. Asymmetric Response of the Equatorial Pacific SST to Climate Warming and Cooling

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Fukai [Physical Oceanography Laboratory/Qingdao Collaborative Innovation Center of Marine Science and Technology, Ocean University of China, and Qingdao National Laboratory for Marine Science and Technology, Qingdao, China; Luo, Yiyong [Physical Oceanography Laboratory/Qingdao Collaborative Innovation Center of Marine Science and Technology, Ocean University of China, and Qingdao National Laboratory for Marine Science and Technology, Qingdao, China; Lu, Jian [Atmospheric Sciences and Global Change Division, Pacific Northwest National Laboratory, Richland, Washington; Garuba, Oluwayemi [Atmospheric Sciences and Global Change Division, Pacific Northwest National Laboratory, Richland, Washington; Wan, Xiuquan [Physical Oceanography Laboratory/Qingdao Collaborative Innovation Center of Marine Science and Technology, Ocean University of China, and Qingdao National Laboratory for Marine Science and Technology, Qingdao, China

    2017-09-01

    The response of the equatorial Pacific Ocean to heat fluxes of equal amplitude but opposite sign is investigated using the Community Earth System Model (CESM). Results show a strong asymmetry in SST changes. In the eastern equatorial Pacific (EEP), the warming responding to the positive forcing exceeds the cooling to the negative forcing; while in the western equatorial Pacific (WEP), it is the other way around and the cooling surpasses the warming. This leads to a zonal dipole asymmetric structure, with positive values in the east and negative values in the west. A surface heat budget analysis suggests that the SST asymmetry is mainly resulted from the oceanic horizontal advection and vertical entrainment, with both of their linear and nonlinear components playing a role. For the linear component, its change appears to be more significant over the EEP (WEP) in the positive (negative) forcing scenario, favoring the seesaw pattern of the SST asymmetry. For the nonlinear component, its change acts to warm (cool) the EEP (WEP) in both scenarios, also favorable for the development of the SST asymmetry. Additional experiments with a slab ocean confirm the dominant role of ocean dynamical processes for this SST asymmetry. The net surface heat flux, in contrast, works to reduce the SST asymmetry through its shortwave radiation and latent heat flux components, with the former being related to the nonlinear relationship between SST and convection, and the latter being attributable to Newtonian damping and air-sea stability effects. The suppressing effect of shortwave radiation on SST asymmetry is further verified by partially coupled overriding experiments.

  20. Instabilities of continuously stratified zonal equatorial jets in a periodic channel model

    Directory of Open Access Journals (Sweden)

    S. Masina

    Full Text Available Several numerical experiments are performed in a nonlinear, multi-level periodic channel model centered on the equator with different zonally uniform background flows which resemble the South Equatorial Current (SEC. Analysis of the simulations focuses on identifying stability criteria for a continuously stratified fluid near the equator. A 90 m deep frontal layer is required to destabilize a zonally uniform, 10° wide, westward surface jet that is symmetric about the equator and has a maximum velocity of 100 cm/s. In this case, the phase velocity of the excited unstable waves is very similar to the phase speed of the Tropical Instability Waves (TIWs observed in the eastern Pacific Ocean. The vertical scale of the baroclinic waves corresponds to the frontal layer depth and their phase speed increases as the vertical shear of the jet is doubled. When the westward surface parabolic jet is made asymmetric about the equator, in order to simulate more realistically the structure of the SEC in the eastern Pacific, two kinds of instability are generated. The oscillations that grow north of the equator have a baroclinic nature, while those generated on and very close to the equator have a barotropic nature. 

    This study shows that the potential for baroclinic instability in the equatorial region can be as large as at mid-latitudes, if the tendency of isotherms to have a smaller slope for a given zonal velocity, when the Coriolis parameter vanishes, is compensated for by the wind effect.

    Key words. Oceanography: general (equatorial oceanography; numerical modeling – Oceanography: physics (fronts and jets

  1. Instabilities of continuously stratified zonal equatorial jets in a periodic channel model

    Directory of Open Access Journals (Sweden)

    S. Masina

    2002-05-01

    Full Text Available Several numerical experiments are performed in a nonlinear, multi-level periodic channel model centered on the equator with different zonally uniform background flows which resemble the South Equatorial Current (SEC. Analysis of the simulations focuses on identifying stability criteria for a continuously stratified fluid near the equator. A 90 m deep frontal layer is required to destabilize a zonally uniform, 10° wide, westward surface jet that is symmetric about the equator and has a maximum velocity of 100 cm/s. In this case, the phase velocity of the excited unstable waves is very similar to the phase speed of the Tropical Instability Waves (TIWs observed in the eastern Pacific Ocean. The vertical scale of the baroclinic waves corresponds to the frontal layer depth and their phase speed increases as the vertical shear of the jet is doubled. When the westward surface parabolic jet is made asymmetric about the equator, in order to simulate more realistically the structure of the SEC in the eastern Pacific, two kinds of instability are generated. The oscillations that grow north of the equator have a baroclinic nature, while those generated on and very close to the equator have a barotropic nature.  This study shows that the potential for baroclinic instability in the equatorial region can be as large as at mid-latitudes, if the tendency of isotherms to have a smaller slope for a given zonal velocity, when the Coriolis parameter vanishes, is compensated for by the wind effect.Key words. Oceanography: general (equatorial oceanography; numerical modeling – Oceanography: physics (fronts and jets

  2. Study of the equatorial ionosphere behavior over Brazilian region during the last two solar minima

    Science.gov (United States)

    Nicoli Candido, C. M.; Batista, I. S.

    2013-12-01

    The recent solar cycle 23-24 presented an unusually deep and long lasting minimum activity period. The impact of this solar minimum on the system magnetosphere-thermosphere-ionosphere has been the subject of several studies. In this study we use the measurements by digisondes installed in the Brazilian sector to investigate the climatology of the ionospheric parameters over Sao Luis (2.33 S degrees, 44.2 W degrees, dip angle: -6.7), an equatorial site, and over Cachoeira Paulista (23S degrees, 45 W degrees, dip angle: -37), a location over the southern crest of the equatorial ionospheric anomaly (EIA). The ionograms were manually scaled in order to extract the ionospheric parameters: hmF2 (the F2 layer peak height, in km) and foF2 (the F2 layer critical frequency, in MHz). The critical frequency is related to the peak electron density of the F2-layer, NmF2, where: NmF2= 1.24 x 1010 (foF2)2 el.m-3. We determine the monthly average values of these parameters to investigate the local time and the seasonal dependence on the solar activity. We also compare the ionospheric behavior during the last two solar minima period: the solar cycle 22-23 (1996) and the solar cycle 23-24 (2008-2009). It is observed that in general the plasma densities and F-region heights are lower in the recent solar minimum, compared to the last one, especially for lower latitude region. In addition, we observe the occurrence of F-region plasma irregularities around local midnight and during post-midnight hours, which present morphological features that are distinct from typical irregularities associated with post sunset equatorial spread-F. We discuss the dependence of the ionospheric behavior on the solar flux.

  3. Water-mass evolution in the Cretaceous Western Interior Seaway of North America and equatorial Atlantic

    Directory of Open Access Journals (Sweden)

    J. S. Eldrett

    2017-07-01

    Full Text Available The Late Cretaceous Epoch was characterized by major global perturbations in the carbon cycle, the most prominent occurring near the Cenomanian–Turonian (CT transition marked by Oceanic Anoxic Event 2 (OAE-2 at 94.9–93.7 Ma. The Cretaceous Western Interior Seaway (KWIS was one of several epicontinental seas in which a complex water-mass evolution was recorded in widespread sedimentary successions. This contribution integrates new data on the main components of organic matter, geochemistry, and stable isotopes along a north–south transect from the KWIS to the equatorial western Atlantic and Southern Ocean. In particular, cored sedimentary rocks from the Eagle Ford Group of west Texas (∼ 90–98 Ma demonstrate subtle temporal and spatial variations in palaeoenvironmental conditions and provide an important geographic constraint for interpreting water-mass evolution. High-latitude (boreal–austral, equatorial Atlantic Tethyan and locally sourced Western Interior Seaway water masses are distinguished by distinct palynological assemblages and geochemical signatures. The northward migration of an equatorial Atlantic Tethyan water mass into the KWIS occurred during the early–middle Cenomanian (98–95 Ma followed by a major re-organization during the latest Cenomanian–Turonian (95–94 Ma as a full connection with a northerly boreal water mass was established during peak transgression. This oceanographic change promoted de-stratification of the water column and improved oxygenation throughout the KWIS and as far south as the Demerara Rise off Suriname. In addition, the recorded decline in redox-sensitive trace metals during the onset of OAE-2 likely reflects a genuine oxygenation event related to open water-mass exchange and may have been complicated by variable contribution of organic matter from different sources (e.g. refractory/terrigenous material, requiring further investigation.

  4. Nitrogen uptake and regeneration pathways in the equatorial Pacific: a basin scale modeling study

    Directory of Open Access Journals (Sweden)

    R. Le Borgne

    2009-11-01

    Full Text Available It is well known that most primary production is fueled by regenerated nitrogen in the open ocean. Therefore, studying the nitrogen cycle by focusing on uptake and regeneration pathways would advance our understanding of nitrogen dynamics in the marine ecosystem. Here, we carry out a basin-scale modeling study, by assessing model simulations of nitrate and ammonium, and rates of nitrate uptake, ammonium uptake and regeneration in the equatorial Pacific. Model-data comparisons show that the model is able to reproduce many observed features of nitrate, ammonium, such as the deep ammonium maximum (DAM. The model also reproduces the observed de-coupling of ammonium uptake and regeneration, i.e., regeneration rate greater than uptake rate in the lower euphotic zone. The de-coupling largely explains the observed DAM in the equatorial Pacific Ocean. Our study indicates that zooplankton excretion and remineralization of organic nitrogen play a different role in nitrogen regeneration. Rates of zooplankton excretion vary from <0.01 mmol m−3 d−1 to 0.1 mmol m−3 d−1 in the upper euphotic zone while rates of remineralization fall within a narrow range (0.015–0.025 mmol m−3 d−1 . Zooplankton excretion contributes up to 70% of total ammonium regeneration in the euphotic zone, and is largely responsible for the spatial variability of nitrogen regeneration. However, remineralization provides a steady supply of ammonium in the upper ocean, and is a major source of inorganic nitrogen for the oligotrophic regions. Overall, ammonium generation and removal are approximately balanced over the top 150 m in the equatorial Pacific.

  5. Impacts of the IOD-associated temperature and salinity anomalies on the intermittent equatorial undercurrent anomalies

    Science.gov (United States)

    Li, Junde; Liang, Chujin; Tang, Youmin; Liu, Xiaohui; Lian, Tao; Shen, Zheqi; Li, Xiaojing

    2017-11-01

    The study of Equatorial Undercurrent (EUC) has attracted a broad attention in recent years due to its strong response and feedback to the Indian Ocean Dipole. In this paper, we first produce a high-quality simulation of three-dimensional temperature, salinity and zonal current simulation from 1982 to 2014, using a high-resolution ocean general circulation model. On this basis, with two sensitivity experiments, we investigate the role of temperature and salinity anomalies in driving and enhancing the EUC during the positive IOD events by examining the variation of the EUC seasonal cycle and diagnosing the zonal momentum budget along the equatorial Indian Ocean. Our results show that during January-March, the EUC can appear along the entire equatorial Indian Ocean in all years, but during August-November, the EUC can appear and reach the eastern Indian Ocean only during the positive IOD events. The zonal momentum budget analysis indicates that the pressure gradient force contributes most to the variation of the eastward acceleration of zonal currents in the subsurface. During the positive IOD events, strong negative subsurface temperature anomalies exist in the eastern Indian Ocean, with negative surface salinity anomalies in the central and eastern Indian Ocean, resulting in a large pressure gradient force to drive EUC during the August-November. Further, the results of two sensitivity experiments indicate that the temperature anomalies significantly impact the pressure gradient force, playing a leading role in driving the EUC, while the surface salinity anomalies can secondarily help to intensify the eastward EUC through increasing the zonal density gradient in the eastern Indian Ocean and impacting the vertical momentum advection in the subsurface.

  6. Equatorial Oscillation and Planetary Wave Activity in Saturn's Stratosphere Through the Cassini Epoch

    Science.gov (United States)

    Guerlet, S.; Fouchet, T.; Spiga, A.; Flasar, F. M.; Fletcher, L. N.; Hesman, B. E.; Gorius, N.

    2018-01-01

    Thermal infrared spectra acquired by Cassini/Composite InfraRed Spectrometer (CIRS) in limb-viewing geometry in 2015 are used to derive 2-D latitude-pressure temperature and thermal wind maps. These maps are used to study the vertical structure and evolution of Saturn's equatorial oscillation (SEO), a dynamical phenomenon presenting similarities with the Earth's quasi-biennal oscillation (QBO) and semi-annual oscillation (SAO). We report that a new local wind maximum has appeared in 2015 in the upper stratosphere and derive the descent rates of other wind extrema through time. The phase of the oscillation observed in 2015, as compared to 2005 and 2010, remains consistent with a ˜15 year period. The SEO does not propagate downward at a regular rate but exhibits faster descent rate in the upper stratosphere, combined with a greater vertical wind shear, compared to the lower stratosphere. Within the framework of a QBO-type oscillation, we estimate the absorbed wave momentum flux in the stratosphere to be on the order of ˜7 × 10-6 N m-2. On Earth, interactions between vertically propagating waves (both planetary and mesoscale) and the mean zonal flow drive the QBO and SAO. To broaden our knowledge on waves potentially driving Saturn's equatorial oscillation, we searched for thermal signatures of planetary waves in the tropical stratosphere using CIRS nadir spectra. Temperature anomalies of amplitude 1-4 K and zonal wave numbers 1 to 9 are frequently observed, and an equatorial Rossby (n = 1) wave of zonal wave number 3 is tentatively identified in November 2009.

  7. Timelike and null equatorial geodesics in the Bonnor-Sackfield relativistic disk

    Directory of Open Access Journals (Sweden)

    Guillermo A. González

    2011-06-01

    Full Text Available A study of timelike and null equatorial geodesics in the BonnorSackfield relativistic thin disk is presented. The motion of test particles in the equatorial plane is analyzed, both for the newtonian thin disk model as for the corresponding relativistic disk. The nature of the possible orbits is studied by means of a qualitative analysis of the effective potential and by numerically solving the motion equation for radial and non-radial equatorial trajectories. The existence of stable, unstable and marginally stable circular orbits is analyzed, both for the newtonian and relativistic case. Examples of the numerical results, obtained with some simple values of the parameters, are presented. Resumen. En este trabajo se presenta un estudio de las geodésicas temporales y nulas en el disco delgado relativista y newtoniano de Bonnor-Sackfield. Se analiza el movimiento de las partículas de prueba en el plano ecuatorial, tanto para el modelo newtoniano del disco delgado como para el disco relativista correspondiente. La naturaleza de las órbitas posibles se estudia por medio de un análisis cualitativo del potencial efectivo, y numéricamente mediante la solución de la ecuación de movimiento de las trayectorias ecuatorial radial y no radial: Se analiza la existencia de órbitas estables, circulares inestables y estables marginalmente, tanto para el caso newtoniano, como el relativista. Se presentan ejemplos de los resultados numéricos obtenidos con algunos valores de los parámetros simples.

  8. Evidence of late Palaeocene-early Eocene equatorial rain forest refugia in southern Western Ghats, India.

    Science.gov (United States)

    Prasad, V; Farooqui, A; Tripathi, S K M; Garg, R; Thakur, B

    2009-11-01

    Equatorial rain forests that maintain a balance between speciation and extinction are hot-spots for studies of biodiversity. Western Ghats in southern India have gained attention due to high tropical biodiversity and endemism in their southern most area. We attempted to track the affinities of the pollen fl ora of the endemic plants of Western Ghat area within the fossil palynoflora of late Palaeocene-early Eocene (approximately 55-50 Ma) sedimentary deposits of western and northeastern Indian region. The study shows striking similarity of extant pollen with twenty eight most common fossil pollen taxa of the early Palaeogene. Widespread occurrences of coal and lignite deposits during early Palaeogene provide evidence of existence of well diversified rain forest community and swampy vegetation in the coastal low lying areas all along the western and northeastern margins of the Indian subcontinent. Prevalence of excessive humid climate during this period has been seen as a result of equatorial positioning of Indian subcontinent, superimposed by a long term global warming phase (PETM and EECO) during the early Palaeogene. The study presents clear evidence that highly diversifi ed equatorial rain forest vegetation once widespread in the Indian subcontinent during early Palaeogene times, are now restricted in a small area as a refugia in the southernmost part of the Western Ghat area. High precipitation and shorter periods of dry months seem to have provided suitable environment to sustain lineages of ancient tropical vegetation in this area of Western Ghats in spite of dramatic climatic changes subsequent to the post India-Asia collision and during the Quaternary and Recent times.

  9. Glass Stronger than Steel

    Science.gov (United States)

    Yarris, Lynn

    2011-03-28

    A new type of damage-tolerant metallic glass, demonstrating a strength and toughness beyond that of steel or any other known material, has been developed and tested by a collaboration of researchers from Berkeley Lab and Caltech.

  10. Are Tornadoes Getting Stronger?

    Science.gov (United States)

    Elsner, J.; Jagger, T.

    2013-12-01

    A cumulative logistic model for tornado damage category is developed and examined. Damage path length and width are significantly correlated to the odds of a tornado receiving the next highest damage category. Given values for the cube root of path length and square root of path width, the model predicts a probability for each category. The length and width coefficients are insensitive to the switch to the Enhanced Fujita (EF) scale and to distance from nearest city although these variables are statistically significant in the model. The width coefficient is sensitive to whether or not the tornado caused at least one fatality. This is likely due to the fact that the dimensions and characteristics of the damage path for such events are always based on ground surveys. The model predicted probabilities across the categories are then multiplied by the center wind speed from the categorical EF scale to obtain an estimate of the highest tornado wind speed on a continuous scale in units of meters per second. The estimated wind speeds correlate at a level of .82 (.46, .95) [95% confidence interval] to wind speeds estimated independently from a doppler radar calibration. The estimated wind speeds allow analyses to be done on the tornado database that are not possible with the categorical scale. The modeled intensities can be used in climatology and in environmental and engineering applications. More work needs to be done to understand the upward trends in path length and width. The increases lead to an apparent increase in tornado intensity across all EF categories.

  11. Impact of protein and ligand impurities on ITC-derived protein-ligand thermodynamics.

    Science.gov (United States)

    Grüner, Stefan; Neeb, Manuel; Barandun, Luzi Jakob; Sielaff, Frank; Hohn, Christoph; Kojima, Shun; Steinmetzer, Torsten; Diederich, François; Klebe, Gerhard

    2014-09-01

    The thermodynamic characterization of protein-ligand interactions by isothermal titration calorimetry (ITC) is a powerful tool in drug design, giving valuable insight into the interaction driving forces. ITC is thought to require protein and ligand solutions of high quality, meaning both the absence of contaminants as well as accurately determined concentrations. Ligands synthesized to deviating purity and protein of different pureness were titrated by ITC. Data curation was attempted also considering information from analytical techniques to correct stoichiometry. We used trypsin and tRNA-guanine transglycosylase (TGT), together with high affinity ligands to investigate the effect of errors in protein concentration as well as the impact of ligand impurities on the apparent thermodynamics. We found that errors in protein concentration did not change the thermodynamic properties obtained significantly. However, most ligand impurities led to pronounced changes in binding enthalpy. If protein binding of the respective impurity is not expected, the actual ligand concentration was corrected for and the thus revised data compared to thermodynamic properties obtained with the respective pure ligand. Even in these cases, we observed differences in binding enthalpy of about 4kJ⋅mol(-1), which is considered significant. Our results indicate that ligand purity is the critical parameter to monitor if accurate thermodynamic data of a protein-ligand complex are to be recorded. Furthermore, artificially changing fitting parameters to obtain a sound interaction stoichiometry in the presence of uncharacterized ligand impurities may lead to thermodynamic parameters significantly deviating from the accurate thermodynamic signature. Copyright © 2014 Elsevier B.V. All rights reserved.

  12. {sup 10}Be in rhodochrosite nodules from Neogene sediments along the Galapagos Ridge, equatorial Pacific

    Energy Technology Data Exchange (ETDEWEB)

    Aldahan, A., E-mail: ala.aldahan@geo.uu.s [Department of Earth Sciences, Uppsala University, Uppsala (Sweden); Department of Geology, United Arab Emirates University, Al Ain (United Arab Emirates); Morad, S. [Department of Earth Sciences, Uppsala University, Uppsala (Sweden); Department of Petroleum Geosciences, Petroleum Institute, Abu Dhabi (United Arab Emirates); Possnert, G. [Tandem Laboratory, Uppsala University, Uppsala (Sweden); Sturesson, U. [Department of Earth Sciences, Uppsala University, Uppsala (Sweden); ElSaiy, A. [Department of Geology, United Arab Emirates University, Al Ain (United Arab Emirates)

    2010-04-15

    Microcrystalline, calcian rhodochrosite occurs as nodules around burrows in late Neogene pelagic sediments from the Galapagos Ridge in the Guatemala Basin, eastern equatorial Pacific (DSDP Leg 68; Site 503). {sup 10}Be isotope revealed that the rhodochrosite nodules have formed under growth conditions much faster than those reported for Fe-Mn nodules. The overall REE patterns of the nodules and host pelagic sediments indicate element derivation mainly from marine pore water. However, variations in the shale normalised Eu values suggest influx of hydrothermal fluids into mounds area at Galapagos, which is also evidenced by the similar minor and major element contents in the nodules and host sediments.

  13. Late Quaternary surface circulation in the east equatorial South Atlantic: Evidence from Alkenone sea surface temperatures

    Science.gov (United States)

    Schneider, Ralph R.; Müller, Peter J.; Ruhland, GöTz

    1995-04-01

    Angola Basin and Walvis Ridge records of past sea surface temperatures (SST) derived from the alkenone Uk37 index are used to reconstruct the surface circulation in the east equatorial South Atlantic for the last 200,000 years. Comparison of SST estimates from surface sediments between 5° and 20°S with modern SST data suggests that the alkenone temperatures represent annual mean values of the surface mixed layer. Alkenone-derived temperatures for the warm climatic maxima of the Holocene and the penultimate interglacial are 1 to 4°C higher than latest Holocene values. All records show glacial to interglacial differences of about 3.5°C in annual mean SST, which is about 1.5°C greater than the difference estimated by CLIMAP (1981) for the eastern Angola Basin. At the Walvis Ridge, significant SST variance is observed at all of the Earth's orbital periodicities. SST records from the Angola Basin vary predominantly at 23- and 100-kyr periodicities. For the precessional cycle, SST changes at the Walvis Ridge correspond to variations of boreal summer insolation over Africa and lead ice volume changes, suggesting that the east equatorial South Atlantic is sensitive to African monsoon intensity via trade-wind zonality. Angola Basin SST records lag those from the Walvis Ridge and the equatorial Atlantic by about 3 kyr. The comparison of Angola Basin and Walvis Ridge SST records implies that the Angola-Benguela Front (ABF) (currently at about 14-16°S) has remained fairly stationary between 12° and 20°S (the limits of our cores) during the last two glacial-interglacial cycles. The temperature contrast associated with the ABF exhibits a periodic 23-kyr variability which is coherent with changes in boreal summer insolation over Africa. These observations suggest that surface waters north of the present ABF have not directly responded to monsoon-modulated changes in the trade-wind vector, that the central field of zonally directed trades in the southern hemisphere was not

  14. Hiss or equatorial noise? Ambiguities in analyzing suprathermal ion plasma wave resonance

    Czech Academy of Sciences Publication Activity Database

    Sarno-Smith, L. K.; Liemohn, M. W.; Skoug, R. M.; Santolík, Ondřej; Morley, S. K.; Breneman, A.; Larsen, B. A.; Reeves, G.; Wygant, J. R.; Hospodarsky, G.; Kletzing, C.; Moldwin, M. B.; Katus, R. M.; Zou, S.

    2016-01-01

    Roč. 121, č. 10 (2016), s. 9619-9631 ISSN 2169-9380 R&D Projects: GA MŠk(CZ) LH15304 Grant - others:AV ČR(CZ) AP1401 Program:Akademická prémie - Praemium Academiae Institutional support: RVO:68378289 Keywords : equatorial noise * low-energy ions * plasma waves * plasmasphere * plasmaspheric hiss Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.733, year: 2016 http://onlinelibrary.wiley.com/doi/10.1002/2016JA022975/abstract

  15. Characteristics of equatorial gravity waves derived from mesospheric airglow imaging observations

    Directory of Open Access Journals (Sweden)

    S. Suzuki

    2009-04-01

    Full Text Available We present the characteristics of small-scale (<100 km gravity waves in the equatorial mesopause region derived from OH airglow imaging observations at Kototabang (100.3° E, 0.2° S, Indonesia, from 2002 to 2005. We adopted a method that could automatically detect gravity waves in the airglow images using two-dimensional cross power spectra of gravity waves. The propagation directions of the waves were likely controlled by zonal filtering due to stratospheric mean winds that show a quasi-biennial oscillation (QBO and the presence of many wave sources in the troposphere.

  16. Blow-up of solutions to the rotation b-family system modeling equatorial water waves

    Directory of Open Access Journals (Sweden)

    Min Zhu

    2018-03-01

    Full Text Available We consider the blow-up mechanism to the periodic generalized rotation b-family system (R-b-family system. This model can be derived from the f-plane governing equations for the geographical water waves with a constant underlying current in the equatorial water waves with effect of the Coriolis force. When b=2, it is a rotation two-component Camassa-Holm (R2CH system. We consider the periodic R2CH system when linear dispersion is absent (which model is called r2CH system and derive two finite-time blow-up results.

  17. Central Pacific El Niño equatorial wave dynamics (1990-2012)

    Science.gov (United States)

    Mosquera-Vásquez, K.; Dewitte, B.; Illig, S.

    2013-12-01

    It is now recognized that two types of El Niño have existed over the last five decades, the so-called canonical Eastern Pacific El Niño with peak anomaly in the eastern Pacific and the Central Pacific El Niño that develops in the central equatorial Pacific. The dynamics of the latter remain unclear mostly because of the delicate balance between feedback processes in the central equatorial Pacific. Here we investigate the role of the equatorial Kelvin wave on the development of SST anomalies over 1989-2012, contrasting the extreme 1997/98 El Niño events with all the other moderate events during this period, and differenciating intraseasonal and interannual timescales. As a first step, the equatorial Kelvin wave is estimated based on an OGCM simulation thoroughly validated from in situ observations. It is showed that the seasonal evolution of the intraseasonal Kelvin wave (IEK) activity is distinct during CP events than during the 1997/98 El Niño, the variance peaking in boreal winter for CP events. CP events differ in terms of the duration of their warming and cooling phases, which motivates the use of the SST tendency as an index for compositing events. A composite normalised mixed-layer heat budget is thus derived that focuses on the wave-induced advection terms. The results indicate that there is no fundamental difference between strong and moderate events in terms of the relative balance between advection terms at interannual timescales in the central Pacific. In particular the anomalous zonal advection of climatological temperature has a comparable contribution to the rate of SST change. The results also indicate that the wave-induced advection accounts for ~50% of the explained variance of the total zonal anomalous advection in the central Pacific versus ~80% for the locally wind-driven zonal advection, and this has not changed over the record. Larger differences between events are found for the intraseasonal timescales, with in particular an increased

  18. Equatorial spread F and plasma bubbles: Preliminary results from the COPEX campaign

    Science.gov (United States)

    Batista, I.; Abdu, M.; Reinisch, B.; de Paula, E.; Groves, K.

    2003-04-01

    The Conjugate Point Equatorial Experiment (COPEX) was conducted in Brazil from October 1 to December 10, 2002. The configuration of the experiment was planed in such a way that the equipments should be located in three sites along a magnetic meridian, one at the magnetic equator and the other two at magnetically conjugate points. The magnetic conjugate points should be located such that the conjugate E layers were field line mapped to the F layer peak, or to the bottomside, over the magnetic equator. The three selected locations were Campo Grande (20.5 S, 54.7 W, southern conjugate point); Boa Vista (2.8 N, 60.7 W, northern conjugate point) and Cachimbo (9.5 S, 54.8 W, magnetic equatorial point). Various instruments such as Digital Portable Sounders (DPS-4), optical imagers, GPS receivers for scintillation monitoring and for TEC measurements, magnetometers, HF receivers and a 50 MHz radar were operated during the campaign. The campaign was coordinated by the Aeronomy group at the Brazilian National Institute for Space Research (Instituto Nacional de Pesquisas Espaciais- INPE), in collaboration with the Brazilian Air Force group from CTA (Centro Técnico Aeroespacial) and with international groups from the Center for Atmospheric Research, University of Massachusetts Lowell (Lowell, MA, USA), the Air Force Research Laboratory Space Vehicles Directorate (AFRL/VSBX, Hanscom AFB, MA, USA), and the Japanese group from the Communication Research Laboratory (CRL), Tokyo. The data collected during the campaign are been used to study the equatorial spread F (ESF), a phenomena that produces large turbulent like variations of electron density at F region heights producing large index of refraction variations. ESF occurs in association with the plasma depleted flux tubes, known as plasma bubbles, which develop at the dusk hours into vertically extended formations extending to 1500 km over the magnetic equator and thousands of kilometers ( 25 ) into the low latitude ionosphere

  19. Different types of whistler mode chorus in the equatorial source region

    Czech Academy of Sciences Publication Activity Database

    Taubenschuss, Ulrich; Santolík, Ondřej; Graham, D. B.; Fu, H.; Khotyaintsev, Y. V.; Le Contel, O.

    2015-01-01

    Roč. 42, č. 20 (2015), s. 8271-8279 ISSN 0094-8276 R&D Projects: GA ČR(CZ) GAP209/11/2280; GA MŠk LH12231 Grant - others:AV ČR(CZ) AP1401 Program:Akademická prémie - Praemium Academiae Institutional support: RVO:68378289 Keywords : whistler mode * chorus * equatorial source * wave normals * Gendrin angle * spectral gap Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 4.212, year: 2015 http://onlinelibrary.wiley.com/doi/10.1002/2015GL066004/abstract

  20. The response of the equatorial Pacific Ocean to a westerly wind burst in May 1986

    Science.gov (United States)

    McPhaden, Michael J.; Freitag, H. Paul; Hayes, Stanley P.; Taft, Bruce A.; Chen, Zeshi; Wyrtki, Klaus

    1988-09-01

    Western Pacific westerly wind bursts of 1- to 3-week duration are potentially important in triggering and sustaining El Niño-Southern Oscillation events. One such burst of 10-day duration and maximum speeds of greater than 10 m s-1 occurred in May 1986 west of the date line. The response to this westerly wind burst is documented from equatorial current meter moorings, thermistor chain moorings, and sea level and hydrographic data. At 0°, 165°E in the western Pacific the thermocline was depressed by 25 m, sea surface temperature dropped by 0.3°-0.4°C, and sea level rose by 10-15 cm a few days after the maximum in westerly wind speed. Likewise, the South Equatorial Current rapidly accelerated eastward and attained speeds in excess of 100 cm s-1. Vertical shear in an approximately 100 m deep surface layer reversed within a few days of the winds, consistent with a simple model of equatorial mixed layer dynamics in which vertical eddy viscosities are inferred to be O(100 cm2 s-1). A sharp Kelvin wavelike pulse in sea level propagated out of the directly forced region into the central and eastern Pacific. The pulse took 45 days to travel from Tarawa (1°N, 173°E) to La Libertad (2°S, 81°W) on the South American coast, at an average phase speed of about 300 cm s-1. This is of the same order of magnitude as, but significantly higher than, the phase speed of a first baroclinic mode Kelvin wave and is probably the result of Doppler shifting by the Equatorial Undercurrent. A rise in sea surface temperature of about 1°C in 2 days occurred at 0°N, 110°W with the passage of the pulse. However, coincidental meridional advection of a sharp sea surface temperature front, rather than zonal advection of downwelling associated with the pulse, appears to be responsible for this warming. The relevance of this wind-forced pulse to the subsequent evolution of the 1986-1987 El Niño-Southern Oscillation event is discussed in the light of these observations.

  1. Geochronological correlation of the late Precambrian sequences on and around the stable zones of Equatorial Africa

    International Nuclear Information System (INIS)

    Cahen, L.

    1982-01-01

    Very few radiometric age determinations have a bearing on the late Precambrian sequences of the stable zones of Equatorial Africa. A geochronological correlation of these sequences must therefore rest upon a compilation of ages from these stable zones and the corresponding mobile zones. About 15 ages of varying precision more or less well tied up with the stratigraphical sequences, together with results of the study of stromatolite assemblages allow a provisional correlation to be made. One conclusion of this correlation is that most mixtites surrounding the Congo basin are in a 950 +- 50 Ma age bracket and are presumably to be correlated. (Auth.)

  2. Equatorial Scintillation Predictions from C/NOFS Planar Langmuir Probe Electron Density Fluctuation Data

    Science.gov (United States)

    2014-09-05

    Brasil Tel: 55 21 3527 1682; Fax: 55 21 3527 1154 E-mail: epoc@cetuc.puc-rio.br FINAL PERFORMANCE REPORT Equatorial scintillation...Costa Centro de Estudos em Telecomunicações/CETUC Rua Marquês de São Vicente, 225 – Gávea 22451-900 Rio de Janeiro - RJ – Brasil Tel: 55 21 3527...Emanoel Costa Centro de Estudos em Telecomunicações/CETUC Rua Marquês de São Vicente, 225 – Gávea 22451-900 Rio de Janeiro - RJ – Brasil Tel: 55

  3. New results on equatorial thermospheric winds and temperatures from Ethiopia, Africa

    OpenAIRE

    F. Tesema; F. Tesema; F. Tesema; R. Mesquita; J. Meriwether; B. Damtie; M. Nigussie; J. Makela; D. Fisher; B. Harding; E. Yizengaw; S. Sanders

    2017-01-01

    Measurements of equatorial thermospheric winds, temperatures, and 630 nm relative intensities were obtained using an imaging Fabry–Perot interferometer (FPI), which was recently deployed at Bahir Dar University in Ethiopia (11.6° N, 37.4° E, 3.7° N magnetic). The results obtained in this study cover 6 months (53 nights of useable data) between November 2015 and April 2016. The monthly-averaged values, which include local winter and equinox seasons, show the magnitude of the ...

  4. Planetary/Kelvin wave modulation of the equatorial ionospheric evening vertical plasma drift and the post sunset spread F developments

    Science.gov (United States)

    Abdu, Mangalathayil A.; Sobral, José; Gurubaran, Subramanian; Brum, Christiano Marques Garnett; Batista, Inez S.; Valentin Bageston, José; Batista, Paulo

    2012-07-01

    Recent studies have shown that the evening prereversal enhancement in the equatorial ionospheric zonal electric field /vertical plasma drift (PRE) and hence post sunset spread F irregularity (ESF) generation are significantly modified by Planetary waves of a few-day (2-, 5-, 7-day) periodicity, although many specific details of which remain to be investigated. Thus the widely observed day to day/short terms variability in the PRE and ESF developments originate not only from the variable forcing (in the form of disturbance electric fields) from magnetosphere, as is well known, but a large part of it arises also from forcing by upward propagating wave from lower atmosphere. In this paper we have analyzed the PRE vertical drifts measured by an equatorial Digisonde (Fortaleza), and the mesospheric zonal and meridional winds as measured by two meteor radars operated at an equatorial site (Sao Joao de Cariri) and a low latitude sites (Cachoeira Paulista), in Brazil, together with mesospheric winds as measured by MF radar at an equatorial site (Tirunelveli) in India. The comparison of these results show the presence of oscillations of around 3 and 5-7 days of periodicities in the evening vertical drift as well as in the mesospheric wind field simultaneously in the Brazilian and Indian longitudes, which are shown to be produced by eastward propagating Equatorial Kelvin wave as well as by westward propagating planetary waves. The effects of these waves on the development of the ESF/plasma bubble irregularities are also studied.

  5. The impact of gambling advertising: Problem gamblers report stronger impacts on involvement, knowledge, and awareness than recreational gamblers.

    Science.gov (United States)

    Hanss, Daniel; Mentzoni, Rune A; Griffiths, Mark D; Pallesen, Ståle

    2015-06-01

    Although there is a general lack of empirical evidence that advertising influences gambling participation, the regulation of gambling advertising is hotly debated among academic researchers, treatment specialists, lobby groups, regulators, and policymakers. This study contributes to the ongoing debate by investigating perceived impacts of gambling advertising in a sample of gamblers drawn from the general population in Norway (n = 6,034). Three dimensions of advertising impacts were identified, representing perceived impacts on (a) gambling-related attitudes, interest, and behavior ("involvement"); (b) knowledge about gambling options and providers ("knowledge"); and (c) the degree to which people are aware of gambling advertising ("awareness"). Overall, impacts were strongest for the knowledge dimension, and, for all 3 dimensions, the impact increased with level of advertising exposure. Those identified as problem gamblers in the sample (n = 57) reported advertising impacts concerning involvement more than recreational gamblers, and this finding was not attributable to differences in advertising exposure. Additionally, younger gamblers reported stronger impacts on involvement and knowledge but were less likely to agree that they were aware of gambling advertising than older gamblers. Male gamblers were more likely than female gamblers to report stronger impacts on both involvement and knowledge. These findings are discussed with regard to existing research on gambling advertising as well as their implications for future research and policy-making. (PsycINFO Database Record (c) 2015 APA, all rights reserved).

  6. Removal of proprioception by BCI raises a stronger body ownership illusion in control of a humanlike robot.

    Science.gov (United States)

    Alimardani, Maryam; Nishio, Shuichi; Ishiguro, Hiroshi

    2016-09-22

    Body ownership illusions provide evidence that our sense of self is not coherent and can be extended to non-body objects. Studying about these illusions gives us practical tools to understand the brain mechanisms that underlie body recognition and the experience of self. We previously introduced an illusion of body ownership transfer (BOT) for operators of a very humanlike robot. This sensation of owning the robot's body was confirmed when operators controlled the robot either by performing the desired motion with their body (motion-control) or by employing a brain-computer interface (BCI) that translated motor imagery commands to robot movement (BCI-control). The interesting observation during BCI-control was that the illusion could be induced even with a noticeable delay in the BCI system. Temporal discrepancy has always shown critical weakening effects on body ownership illusions. However the delay-robustness of BOT during BCI-control raised a question about the interaction between the proprioceptive inputs and delayed visual feedback in agency-driven illusions. In this work, we compared the intensity of BOT illusion for operators in two conditions; motion-control and BCI-control. Our results revealed a significantly stronger BOT illusion for the case of BCI-control. This finding highlights BCI's potential in inducing stronger agency-driven illusions by building a direct communication between the brain and controlled body, and therefore removing awareness from the subject's own body.

  7. Infrared Multiple Photon Dissociation Spectroscopy of a Gas-Phase Oxo-Molybdenum Complex with 1,2-Dithiolene Ligands

    Science.gov (United States)

    2015-01-01

    Electrospray ionization (ESI) in the negative ion mode was used to create anionic, gas-phase oxo-molybdenum complexes with dithiolene ligands. By varying ESI and ion transfer conditions, both doubly and singly charged forms of the complex, with identical formulas, could be observed. Collision-induced dissociation (CID) of the dianion generated exclusively the monoanion, while fragmentation of the monoanion involved decomposition of the dithiolene ligands. The intrinsic structure of the monoanion and the dianion were determined by using wavelength-selective infrared multiple-photon dissociation (IRMPD) spectroscopy and density functional theory calculations. The IRMPD spectrum for the dianion exhibits absorptions that can be assigned to (ligand) C=C, C–S, C—C≡N, and Mo=O stretches. Comparison of the IRMPD spectrum to spectra predicted for various possible conformations allows assignment of a pseudo square pyramidal structure with C2v symmetry, equatorial coordination of MoO2+ by the S atoms of the dithiolene ligands, and a singlet spin state. A single absorption was observed for the oxidized complex. When the same scaling factor employed for the dianion is used for the oxidized version, theoretical spectra suggest that the absorption is the Mo=O stretch for a distorted square pyramidal structure and doublet spin state. A predicted change in conformation upon oxidation of the dianion is consistent with a proposed bonding scheme for the bent-metallocene dithiolene compounds [Lauher, J. W.; Hoffmann, R. J. Am. Chem. Soc.1976, 98, 1729−1742], where a large folding of the dithiolene moiety along the S···S vector is dependent on the occupancy of the in-plane metal d-orbital. PMID:24988369

  8. Gas phase oxidation of alkoxo ligands in bis(peroxo)[MO(O2)2(OR)]- and trisoxo [MO3(OR)]- anions (M = Cr, Mo, W).

    Science.gov (United States)

    Feyel, Sandra; Waters, Tom; O'Hair, Richard A J; Wedd, Anthony G

    2004-12-07

    The anions [M(VI)O(O(2))(2)(OR)](-) and [M(VI)O(3)(OR)](-)(M = Cr, Mo, W; R = H, Me, Et, (n)Pr, (i)Pr) were transferred to the gas phase by the electrospray process. Their decomposition was examined by multistage mass spectrometry and collisional activation experiments. The molybdate and tungstate anions [M(VI)O(O(2))(2)(OR)](-) underwent parallel elimination of aldehyde (ketone) and dioxygen while the equivalent chromate underwent loss of dioxygen only. The peroxo ligands were the source of oxidising equivalents in both reactions. For each alkoxo ligand, the total yield of aldehyde for the tungstate system exceeded that for the molybdate system. Collisional activation of [M(VI)O(3)(OMe)](-) led to clean elimination of formaldehyde with the metal centre supplying the oxidising equivalents. For larger alkoxo ligands, only the chromate centre eliminated aldehyde, while the molybdate and tungstate centres underwent clean loss of alkene. Threshold activation voltages indicated that the peroxo ligands of [W(VI)O(O(2))(2)(OMe)](-) are more oxidising than the tungstate centre of [W(VI)O(3)(OMe)](-). (2)H and (18)O isotope tracing experiments were consistent with a formal hydride transfer mechanism operating for oxidation of alkoxo ligand in each system. In the solid state, anions [M(VI)O(O(2))(2)(OR)](-) are typically pentagonal pyramidal (oxo in apical site) while [M(VI)O(3)(OR)](-) are tetrahedral. The data indicate that an equatorial ligand position is the site of alkoxo oxidation in [M(VI)O(O(2))(2)(OR)](-) anions. Comparisons of the gas phase data with those for a solution phase system are made.

  9. Immobilisation of ligands by radio-derivatized polymers; Immobilisering av ligander med radioderiverte polymerer

    Energy Technology Data Exchange (ETDEWEB)

    Varga, J.M.; Fritsch, P.

    1995-01-30

    The invention relates to radio-derivatized polymers and a method of producing them by contacting non-polymerizable conjugands with radiolysable polymers in the presence of irradiation. The resulting radio-derivatized polymers can be further linked with ligand of organic or inorganic nature to immobilize such ligands. 2 figs., 5 tabs.

  10. A General Ligand Design for Gold Catalysis allowing Ligand-Directed Anti Nucleophilic Attack of Alkynes

    Science.gov (United States)

    Wang, Yanzhao; Wang, Zhixun; Li, Yuxue; Wu, Gongde; Cao, Zheng; Zhang, Liming

    2014-01-01

    Most homogenous gold catalyses demand ≥0.5 mol % catalyst loading. Due to the high cost of gold, these reactions are unlikely to be applicable in medium or large scale applications. Here we disclose a novel ligand design based on the privileged biphenyl-2-phosphine framework that offers a potentially general approach to dramatically lowering catalyst loading. In this design, an amide group at the 3’ position of the ligand framework directs and promotes nucleophilic attack at the ligand gold complex-activated alkyne, which is unprecedented in homogeneous gold catalysis considering the spatial challenge of using ligand to reach antiapproaching nucleophile in a linear P-Au-alkyne centroid structure. With such a ligand, the gold(I) complex becomes highly efficient in catalyzing acid addition to alkynes, with a turnover number up to 99,000. Density functional theory calculations support the role of the amide moiety in directing the attack of carboxylic acid via hydrogen bonding. PMID:24704803

  11. A new class of PN3-pincer ligands for metal–ligand cooperative catalysis

    KAUST Repository

    Li, Huaifeng

    2014-12-01

    Work on a new class of PN3-pincer ligands for metal-ligand cooperative catalysis is reviewed. While the field of the pyridine-based PN3-transition metal pincer complexes is still relatively young, many important applications of these complexes have already emerged. In several cases, the PN3-pincer complexes for metal-ligand cooperative catalysis result in significantly improved or unprecedented activities. The synthesis and coordination chemistry of PN3-pincer ligands are briefly summarized first to cover the synthetic routes for their preparation, followed by a focus review on their applications in catalysis. A specific emphasis is placed on the later section about the role of PN3-pincer ligands\\' dearomatization-rearomatization steps during the catalytic cycles. The mechanistic insights from density functional theory (DFT) calculations are also discussed.

  12. Effects of PPARγ ligands on vascular tone.

    Science.gov (United States)

    Salomone, Salvatore; Drago, Filippo

    2012-06-01

    Peroxisome Proliferator-Activated Receptor γ (PPARγ), originally described as a transcription factor for genes of carbohydrate and lipid metabolism, has been more recently studied in the context of cardiovascular pathophysiology. Here, we review the available data on PPARγ ligands as modulator of vascular tone. PPARγ ligands include: thiazolidinediones (used in the treatment of type 2 diabetes mellitus), glitazars (bind and activate both PPARγ and PPARα), and other experimental drugs (still in development) that exploit the chemistry of thiazolidinediones as a scaffold for PPARγ-independent pharmacological properties. In this review, we examine both short (mostly from in vitro data)- and long (mostly from in vivo data)-term effects of PPARγ ligands that extend from PPARγ-independent vascular effects to PPARγ-dependent gene expression. Because endothelium is a master regulator of vascular tone, we have attempted to differentiate between endothelium-dependent and endothelium-independent effects of PPARγ ligands. Based on available data, we conclude that PPARγ ligands appear to influence vascular tone in different experimental paradigms, most often in terms of vasodilatation (potentially increasing blood flow to some tissues). These effects on vascular tone, although potentially beneficial, must be weighed against specific cardiovascular warnings that may apply to some drugs, such as rosiglitazone.

  13. LIBRA: LIgand Binding site Recognition Application.

    Science.gov (United States)

    Hung, Le Viet; Caprari, Silvia; Bizai, Massimiliano; Toti, Daniele; Polticelli, Fabio

    2015-12-15

    In recent years, structural genomics and ab initio molecular modeling activities are leading to the availability of a large number of structural models of proteins whose biochemical function is not known. The aim of this study was the development of a novel software tool that, given a protein's structural model, predicts the presence and identity of active sites and/or ligand binding sites. The algorithm implemented by ligand binding site recognition application (LIBRA) is based on a graph theory approach to find the largest subset of similar residues between an input protein and a collection of known functional sites. The algorithm makes use of two predefined databases for active sites and ligand binding sites, respectively, derived from the Catalytic Site Atlas and the Protein Data Bank. Tests indicate that LIBRA is able to identify the correct binding/active site in 90% of the cases analyzed, 90% of which feature the identified site as ranking first. As far as ligand binding site recognition is concerned, LIBRA outperforms other structure-based ligand binding sites detection tools with which it has been compared. The application, developed in Java SE 7 with a Swing GUI embedding a JMol applet, can be run on any OS equipped with a suitable Java Virtual Machine (JVM), and is available at the following URL: http://www.computationalbiology.it/software/LIBRAv1.zip. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  14. Dockomatic - automated ligand creation and docking.

    Science.gov (United States)

    Bullock, Casey W; Jacob, Reed B; McDougal, Owen M; Hampikian, Greg; Andersen, Tim

    2010-11-08

    The application of computational modeling to rationally design drugs and characterize macro biomolecular receptors has proven increasingly useful due to the accessibility of computing clusters and clouds. AutoDock is a well-known and powerful software program used to model ligand to receptor binding interactions. In its current version, AutoDock requires significant amounts of user time to setup and run jobs, and collect results. This paper presents DockoMatic, a user friendly Graphical User Interface (GUI) application that eases and automates the creation and management of AutoDock jobs for high throughput screening of ligand to receptor interactions. DockoMatic allows the user to invoke and manage AutoDock jobs on a single computer or cluster, including jobs for evaluating secondary ligand interactions. It also automates the process of collecting, summarizing, and viewing results. In addition, DockoMatic automates creation of peptide ligand .pdb files from strings of single-letter amino acid abbreviations. DockoMatic significantly reduces the complexity of managing multiple AutoDock jobs by facilitating ligand and AutoDock job creation and management.

  15. Dockomatic - automated ligand creation and docking

    Directory of Open Access Journals (Sweden)

    Hampikian Greg

    2010-11-01

    Full Text Available Abstract Background The application of computational modeling to rationally design drugs and characterize macro biomolecular receptors has proven increasingly useful due to the accessibility of computing clusters and clouds. AutoDock is a well-known and powerful software program used to model ligand to receptor binding interactions. In its current version, AutoDock requires significant amounts of user time to setup and run jobs, and collect results. This paper presents DockoMatic, a user friendly Graphical User Interface (GUI application that eases and automates the creation and management of AutoDock jobs for high throughput screening of ligand to receptor interactions. Results DockoMatic allows the user to invoke and manage AutoDock jobs on a single computer or cluster, including jobs for evaluating secondary ligand interactions. It also automates the process of collecting, summarizing, and viewing results. In addition, DockoMatic automates creation of peptide ligand .pdb files from strings of single-letter amino acid abbreviations. Conclusions DockoMatic significantly reduces the complexity of managing multiple AutoDock jobs by facilitating ligand and AutoDock job creation and management.

  16. Chelating ligands for nanocrystals' surface functionalization.

    Science.gov (United States)

    Querner, Claudia; Reiss, Peter; Bleuse, Joël; Pron, Adam

    2004-09-22

    A new family of ligands for the surface functionalization of CdSe nanocrystals is proposed, namely alkyl or aryl derivatives of carbodithioic acids (R-C(S)SH). The main advantages of these new ligands are as follows: they nearly quantitatively exchange the initial surface ligands (TOPO) in very mild conditions; they significantly improve the resistance of nanocrystals against photooxidation because of their ability of strong chelate-type binding to metal atoms; their relatively simple preparation via Grignard intermediates facilitates the development of new bifunctional ligands containing, in addition to the anchoring carbodithioate group, a second function, which enables the grafting of molecules or macromolecules of interest on the nanocrystal surface. To give an example of this approach, we report, for the first time, the grafting of an electroactive oligomer from the polyaniline family-aniline tetramer-on CdSe nanocrystals after their functionalization with 4-formyldithiobenzoic acid. The grafting proceeds via a condensation reaction between the aldehyde group of the ligand and the terminal primary amine group of the tetramer. The resulting organic/inorganic hybrid exhibits complete extinction of the fluorescence of its constituents, indicating efficient charge or energy transfer between the organic and the inorganic semiconductors.

  17. The prospection of uranium and thorium ores in desert country and in equatorial forest regions of the Union Francaise

    International Nuclear Information System (INIS)

    Lecoq, J.J.; Bigotte, G.; Hinault, J.; Leconte, J.R.

    1958-01-01

    Since it was founded, the D.R.E.M. has carried out important prospection work in the overseas territories which now make up the Communaute Francaise. This work, now involving almost a million km 2 , represents an experiment scarcely equalled throughout the world. Research in these territories presents both general and technical difficulties, which are especially severe in countries with extreme climates: deserts or dense equatorial forests. The adaptation of various methods of radioactive ore prospection to these regions is described, and also the results obtained. Three particular examples are given in detail: - general exploration in the Hoggar, and reconnoitring of particular indications; - general exploration in the equatorial forest of French Guyana; - detailed study of a sign of uraniferous occurrences and its surroundings in the equatorial zone (Mounana deposit near Franceville (Gabon)). (author) [fr

  18. Sub-kilometer Simulation of Equatorial Plasma Bubble and Comparison with Satellite Observations

    Science.gov (United States)

    Yokoyama, T.; Pfaff, R. F., Jr.; Stolle, C.; Su, S. Y.

    2016-12-01

    Equatorial plasma bubble (EPB) is a well-known phenomenon in the equatorial ionospheric F region. As it causes severe scintillation in the amplitude and phase of radio signals, it is important to understand and forecast the occurrence of EPB from a space weather point of view. The development of EPB is presently believed as an evolution of the generalized Rayleigh-Taylor instability. We have already developed a 3D high-resolution bubble (HIRB) model with a grid spacing of as small as 1 km and presented nonlinear growth of EPB which shows very turbulent internal structures such as bifurcation and pinching. Recent upgrade of the HIRB model has made it possible to conduct the simulation with sub-kilometer grid spacing. The simulation results can be compared with various in situ satellite observations such as plasma drift velocity, plasma density, magnetic field, and their structures and power spectra, e.g. from the C/NOFS, ROCSAT, CHAMP, or Swarm missions. Our initial results show encouraging agreement between model results and observational data.

  19. Reflection of equatorial Kelvin waves at eastern ocean boundaries Part II: Pacific and Atlantic Oceans

    Directory of Open Access Journals (Sweden)

    J. Soares

    1999-06-01

    Full Text Available The effect of viscosity, non linearities, incident wave period and realistic eastern coastline geometry on energy fluxes are investigated using a shallow water model with a spatial resolution of 1/4 degree in both meridional and zonal directions. Equatorial and mid-latitude responses are considered. It is found that (1 the influence of the coastline geometry and the incident wave period is more important for the westward energy flux than for the poleward flux, and (2 the effect of the inclination of the eastern ocean boundary on the poleward energy flux, for the Pacific and Atlantic Oceans, decline as the period of the incident wave increases. Furthermore, the model simulations suggest that the poleward energy fluxes from meridional boundaries give plausible results for motions of seasonal and annual periods. For comparatively shorter periods, a realistic coastline geometry has to be included for more accurate results. It is recommended that any numerical model involving the reflection of baroclinic Rossby waves (of intraseasonal, seasonal or annual periods on the eastern Pacific or Atlantic Oceans, should consider the effect of the coastline geometry in order to improve the accuracy of the results.Key words. Oceanography: general (climate and interannual variability; equatorial oceanography. Oceanography: physical (eastern boundary currents.

  20. Diagnosing the Growth of Equatorial Typhoon Vamei (2001 from an Energy Standpoint

    Directory of Open Access Journals (Sweden)

    Gin-Rong Liu

    2010-01-01

    Full Text Available Surprisingly, on 27 December 2001, a storm named Typhoon Vamei formed near in Singaporean waters. An examination on the SSM/I-derived rainfall rates and air-sea parameters showed that significant higher latent heat release and air-sea energy flux during convective rainfall activities played a key role in the typhoon¡¦s growth. A quantitative analysis revealed that the energy flux from the ocean to the atmosphere and the latent heat release during the rainfall activities both increased significantly during the initial growth stage. However, the values rapidly decreased just before the storm reached typhoon strength. Separately, in contrast to a case that occurred in 1999, the total thermal energy calculated from Typhoon Vamei¡¦s formation was two times higher. Thus, despite a very weak Coriolis force in the equatorial belt, the special terrain of Borneo Island and narrow channel in the equatorial South China Sea caused a Borneo vortex via northeasterly cold surges, together with the accumulated energy was sufficiently strong enough to induce the formation of Typhoon Vamei.

  1. Long-term acoustic measurement of temperature variations in the Pacific North Equatorial Current

    Science.gov (United States)

    Kaneko, Arata; Zheng, Hong; Nakano, Iwao; Yuan, Gang; Fujimori, Hidetoshi; Yoneyama, Kunio

    1996-07-01

    A 247-km path length sound transmission experiment using a single sound source sending to a remote receiver was performed during February-June 1992 along the latitudinal line of 10°N in the North Equatorial Current off Mindanao Island, Phillipines. The range-averaged temperature was reconstructed at three layers (65-500 m, 500-1500 m, and 1500-3300 m) through the inverse analysis of travel time data obtained between the source and receiver. The temperature remained nearly constant during February-March and increased by 0.8°C for the upper and middle layers and 0.2°C for the lower layer in the subsequent months. A 0.8°C temperature increase was in good agreement with expendable bathythermograph results obtained at the start and finish of the experiment. National Oceanic and Atmospheric Administration advanced very high resolution radiometer images also show evidence of a warming of the surface water by 2.0°C during the same period. It is concluded that this acoustic experiment observed a warm event which took place in the western equatorial Pacific with the decay of the 1991-1992 El Niño.

  2. Filamentary Alfvénic structures excited at the edges of equatorial plasma bubbles

    Directory of Open Access Journals (Sweden)

    R. Pottelette

    2007-11-01

    Full Text Available Recent observations performed by the French DEMETER satellite at altitudes of about 710 km suggest that the generation of equatorial plasma bubbles correlates with the presence of filamentary structures of field aligned currents carried by Alfvén waves. These localized structures are located at the bubble edges. We study the dynamics of the equatorial plasma bubbles, taking into account that their motion is dictated by gravity driven and displacement currents. Ion-polarization currents appear to be crucial for the accurate description of the evolution of plasma bubbles in the high altitude ionosphere. During their eastward/westward motion the bubbles intersect gravity driven currents flowing transversely with respect to the background magnetic field. The circulation of these currents is prohibited by large density depressions located at the bubble edges acting as perfect insulators. As a result, in these localized regions the transverse currents have to be locally closed by field aligned currents. Such a physical process generates kinetic Alfvén waves which appear to be stationary in the plasma bubble reference frame. Using a two-dimensional model and "in situ" wave measurements on board the DEMETER spacecraft, we give estimates for the magnitude of the field aligned currents and the associated Alfvén fields.

  3. Western equatorial African forest-savanna mosaics: a legacy of late Holocene climatic change?

    Directory of Open Access Journals (Sweden)

    A. Ngomanda

    2009-10-01

    Full Text Available Past vegetation and climate changes reconstructed using two pollen records from Lakes Maridor and Nguène, located in the coastal savannas and inland rainforest of Gabon, respectively, provide new insights into the environmental history of western equatorial African rainforests during the last 4500 cal yr BP. These pollen records indicate that the coastal savannas of western equatorial Africa did not exist during the mid-Holocene and instead the region was covered by evergreen rainforests. From ca. 4000 cal yr BP a progressive decline of inland evergreen rainforest, accompanied by the expansion of semi-deciduous rainforest, occurred synchronously with grassland colonisation in the coastal region of Gabon. The contraction of moist evergreen rainforest and the establishment of coastal savannas in Gabon suggest decreasing humidity from ca. 4000 cal yr BP. The marked reduction in evergreen rainforest and subsequent savanna expansion was followed from 2700 cal yr BP by the colonization of secondary forests dominated by the palm, Elaeis guineensis, and the shrub, Alchornea cordifolia (Euphorbiaceae. A return to wetter climatic conditions from about 1400 cal yr BP led to the renewed spread of evergreen rainforest inland, whereas a forest-savanna mosaic still persists in the coastal region. There is no evidence to suggest that the major environmental changes observed were driven by human impact.

  4. Lighting programs for male and female meat quails (Coturnix coturnix) raised in equatorial region.

    Science.gov (United States)

    Aguiar, G C; Freitas, E R; Watanabe, P H; Figueiredo, C W S; Silva, L P; Nascimento, G A J; Lima, R C; Nepomuceno, R C; Sá, N L

    2017-09-01

    The aim of the present study was to evaluate the effect of lighting programs for male and female meat quails raised in an equatorial region on performance and carcass traits. A total of 1,500 sexed quails (Coturnix coturnix) was distributed in a completely randomized design in a 2 × 3 factorial arrangement, with 2 sexes (male and female) and 3 lighting programs (natural, intermittent, and continuous) with 5 replicates of 50 birds. The lighting programs were applied in the period from 7 to 49 d of age, being natural (12 h and 30 min of natural light and 11 h and 30 min of dark), intermittent (12 h and 30 min of natural light and 5 h and 30 min of artificial light, alternating lighting periods with one h and 06 min and periods of darkness with one h and 12 min), and continuous (23 h of natural + artificial light and one h of dark). Regardless of lighting program, female quails were heavier than males, and birds subjected to natural light weighed less than those exposed to continuous and intermittent lighting programs. Quails exposed to intermittent and continuous light presented higher weight gain and feed intake, and worse feed conversion ratio compared to birds under a natural light regimen. It is concluded that in an equatorial region, it is possible to use a lighting program with only natural light for raising male and female meat quails from 7 to 49 d of age. © 2017 Poultry Science Association Inc.

  5. Growth rates, grazing, sinking, and iron limitation of equatorial Pacific phytoplankton

    International Nuclear Information System (INIS)

    Chavez, F.P.; Buck, K.R.; Coale, K.H.; Martin, J.H.; DiTullio, G.R.; Welschmeyer, N.A.; Barber, R.T.; Jacobson, A.C.

    1991-01-01

    Concentrations of phytoplankton and NO 3 are consistently low and high in surface waters of the oceanic eastern and central equatorial Pacific, and phytoplankton populations are dominated by small solitary phytoplankton. Growth rates of natural phytoplankton populations, needed to assess the relative importance of many of the processes considered in the equatorial Pacific, were estimated by several methods. The growth rates of natural phytoplankton populations were found to be ∼0.7 d -1 or 1 biomass doubling d -1 and were similar for all methods. To keep this system in its observed balance requires that loss rates approximate observed growth rates. Grazing rates, measured with a dilution grazing experiment, were high, accounting for a large fraction of the daily production. Additions of various forms of Fe to 5-7-d incubations utilizing ultraclean techniques resulted in significant shifts in autotrophic and heterotrophic assemblages between initial samples, controls, and Fe enrichments, which were presumably due to Fe, grazing by both protistan and metazoan components, and incubation artifacts. Estimated growth rates of small pennate diatoms showed increases in Fe enrichments with respect to controls. The growth rates of the pennate diatoms were similar to those estimated for the larger size fraction of the natural populations

  6. Middle ultraviolet remote sensing of the equatorial thermosphere during a geomagnetic storm

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    A. W. Stephan

    2004-09-01

    Full Text Available We present measurements of the equatorial middle ultraviolet airglow taken during the week of 21-28 May 2000, including a strong geomagnetic storm on 24 May. Limb spectra were taken by the Ionospheric Spectroscopy and Atmospheric Chemistry (ISAAC experiment on the Advanced Research and Global Observation Satellite (ARGOS. OII lines near 247.0nm and NII lines near 214.3nm provide a measure of thermospheric O and N2 changes, respectively. Our results show increases in airglow brightness of both emissions during the storm that we interpret as increases in the concentrations of both species, but the ratio of intensities that correspond to O/N2 is lower than expected during and after the storm. We also invert the emission profiles using discrete inverse theory, to obtain a measure of thermospheric neutral temperatures during this time. Although temperatures increase after the main phase of the storm, the increases do not correlate with the observed features in the intensity ratio. These data could be explained by vertical winds and tides modifying the equatorial neutral composition during storms, in addition to common heating responses.

  7. Middle ultraviolet remote sensing of the equatorial thermosphere during a geomagnetic storm

    Directory of Open Access Journals (Sweden)

    A. W. Stephan

    2004-09-01

    Full Text Available We present measurements of the equatorial middle ultraviolet airglow taken during the week of 21-28 May 2000, including a strong geomagnetic storm on 24 May. Limb spectra were taken by the Ionospheric Spectroscopy and Atmospheric Chemistry (ISAAC experiment on the Advanced Research and Global Observation Satellite (ARGOS. OII lines near 247.0nm and NII lines near 214.3nm provide a measure of thermospheric O and N2 changes, respectively. Our results show increases in airglow brightness of both emissions during the storm that we interpret as increases in the concentrations of both species, but the ratio of intensities that correspond to O/N2 is lower than expected during and after the storm. We also invert the emission profiles using discrete inverse theory, to obtain a measure of thermospheric neutral temperatures during this time. Although temperatures increase after the main phase of the storm, the increases do not correlate with the observed features in the intensity ratio. These data could be explained by vertical winds and tides modifying the equatorial neutral composition during storms, in addition to common heating responses.

  8. Support for equatorial anisotropy of Earth's inner-inner core from seismic interferometry at low latitudes

    Science.gov (United States)

    Wang, Tao; Song, Xiaodong

    2018-03-01

    Anisotropy of Earth's inner core provides a key role to understand its evolution and the Earth's magnetic field. Recently, using autocorrelations from earthquake's coda, we found an equatorial anisotropy of the inner-inner core (IIC), in apparent contrast to the polar anisotropy of the outer-inner core (OIC). To reduce the influence of the polar anisotropy and reduce possible contaminations from the large Fresnel zone of the PKIKP2 and PKIIKP2 phases at low frequencies, we processed coda noise of large earthquakes (10,000-40,000 s after magnitude ≥7.0) from stations at low latitudes (within ±35°) during 1990-2013. Using a number of improved procedures of both autocorrelation and cross-correlation, we extracted 52 array-stacked high-quality empirical Green's functions (EGFs), an increase of over 60% from our previous study. The high-quality data allow us to measure the relative arrival times by automatic waveform cross correlation. The results show large variation (∼10.9 s) in the differential times between the PKIKP2 and PKIIKP2 phases. The estimated influence of the Fresnel zone is insignificant (global dataset, including the fast axis and two low-velocity open rings, thus providing further support for the equatorial anisotropy model of the IIC. Speculations for the shift of the fast axis between the OIC and the IIC include: change of deformation regimes during the inner core history, change of geomagnetic field, and a proto-inner core.

  9. An Analysis of Cassini Observations Regarding the Structure of Jupiter's Equatorial Atmosphere

    Science.gov (United States)

    Choi, David S.; Simon-Miller, Amy A.

    2012-01-01

    A variety of intriguing atmospheric phenomena reside on both sides of Jupiter's equator. 5-micron bright hot spots and opaque plumes prominently exhibit dynamic behavior to the north, whereas compact, dark chevron-shaped features and isolated anticyclonic disturbances periodically occupy the southern equatorial latitudes. All of these phenomena are associated with the vertical and meridional perturbations of Rossby waves disturbing the mean atmospheric state. As previous observational analysis and numerical simulations have investigated the dynamics of the region, an examination of the atmosphere's vertical structure though radiative transfer analysis is necessary for improved understanding of this unique environment. Here we present preliminary analysis of a multispectral Cassini imaging data set acquired during the spacecraft's flyby of Jupiter in 2000. We evaluated multiple methane and continuum spectral channels at available viewing angles to improve constraints on the vertical structure of the haze and cloud layers comprising these interesting features. Our preliminary results indicate distinct differences in the structure for both hemispheres. Upper troposphere hazes and cloud layers are prevalent in the northern equatorial latitudes, but are not present in corresponding southern latitudes. Continued analysis will further constrain the precise structure present in these phenomena and the differences between them.

  10. On the development of equatorial plasma bubbles around midnight hours of June solstice.

    Science.gov (United States)

    Ajith, K. K.; Yamamoto, M.; Yokoyama, T.

    2017-12-01

    Using the 47 MHz Equatorial Atmosphere Radar (EAR) at Kototabang, Indonesia, the nocturnal occurrence of Equatorial Plasma Bubbles (EPBs) were examined during the moderate solar activity years 2011-2012. While the evolution of EPBs were mostly (86%) confined to post-sunset hours (1900 - 2100 LT) during equinoxes, in contrast, the majority of EPBs ( 71%) in June solstice found evolve around the midnight hours (2200 - 0300 LT). The mechanisms behind the fresh evolution of summer time midnight EPBs were investigated through SAMI2 model simulations with a realistic input of background ExB drift variation derived from CINDI IVM on board C/NOFS satellite. The term-by-term analysis of linear growth rate of RT instability indicates that the formation of high flux tube electron content height gradient (KF) (steep vertical gradient) region at higher altitudes is the key factor for the enhanced growth rate of RT instability. The responsible factors are discussed in light of relatively weak westward zonal electric field in the presence of equatorward neutral wind and bottom side recombination around the midnight hours of June solstice.

  11. Relation between equatorial x-ray intensities and isometric twitch forces in frog skeletal muscle

    International Nuclear Information System (INIS)

    Tanaka, Hidehiro; Tameyasu, Tsukasa; Sugi, Haruo

    1983-01-01

    The sartorius muscle of bullfrog (Rana catesbeiana) was mounted vertically in an experimental chamber. The nuscle was continuously perfused with Ringer solution, and stimulated with single 2 msec supramaximal current pulses. The equatorial X-ray diffraction pattern (specimen to detector distance, 40 cm) during isometric twitches was recorded with a linear position-sensitive proportional counter, and the data were registered in a computer memory system. With an increase of temperature from 5 to 22 0 C, the magnitude of peak twitch force was reduced by about 50% with a marked decrease in the duration of mechanical response, while the minimum value of Isub(1.0)/Isub(1.1) attained during a twitch increased by more than twofold. On the other hand, the equatorial reflection from resting and fully tetanized muscles showed no appreciable dependence on temperature, though the steady tetanic force P 0 increased by about 10% with an increase in temperature from 5 to 25 0 C. The intensity ratio is not a linear function of isometric force developed. (Namekawa, k.)

  12. Quantum jointly assisted cloning of an unknown three-dimensional equatorial state

    Science.gov (United States)

    Ma, Peng-Cheng; Chen, Gui-Bin; Li, Xiao-Wei; Zhan, You-Bang

    2018-02-01

    We present two schemes for perfectly cloning an unknown single-qutrit equatorial state with assistance from two and N state preparers, respectively. In the first scheme, the sender wishes to teleport an unknown single-qutrit equatorial state from two state preparers to a remote receiver, and then to create a perfect copy of the unknown state at her location. The scheme consists of two stages. The first stage of the scheme requires the usual teleportation. In the second stage, to help the sender realize the quantum cloning, two state preparers perform single-qutrit projective measurements on their own qutrits from the sender, then the sender can acquire a perfect copy of the unknown state. It is shown that, only if the two state preparers collaborate with each other, the sender can create a copy of the unknown state by means of some appropriate unitary operations. In the second scheme, we generalized the jointly assisted cloning in the first scheme to the case of N state prepares. In the present schemes, the total probability of success for assisted cloning of a perfect copy of the unknown state can reach 1.

  13. Deep-sea environment and biodiversity of the West African Equatorial margin

    Science.gov (United States)

    Sibuet, Myriam; Vangriesheim, Annick

    2009-12-01

    The long-term BIOZAIRE multidisciplinary deep-sea environmental program on the West Equatorial African margin organized in partnership between Ifremer and TOTAL aimed at characterizing the benthic community structure in relation with physical and chemical processes in a region of oil and gas interest. The morphology of the deep Congo submarine channel and the sedimentological structures of the deep-sea fan were established during the geological ZAIANGO project and helped to select study sites ranging from 350 to 4800 m water depth inside or near the channel and away from its influence. Ifremer conducted eight deep-sea cruises on board research vessels between 2000 and 2005. Standardized methods of sampling together with new technologies such as the ROV Victor 6000 and its associated instrumentation were used to investigate this poorly known continental margin. In addition to the study of sedimentary environments more or less influenced by turbidity events, the discovery of one of the largest cold seeps near the Congo channel and deep coral reefs extends our knowledge of the different habitats of this margin. This paper presents the background, objectives and major results of the BIOZAIRE Program. It highlights the work achieved in the 16 papers in this special issue. This synthesis paper describes the knowledge acquired at a regional and local scale of the Equatorial East Atlantic margin, and tackles new interdisciplinary questions to be answered in the various domains of physics, chemistry, taxonomy and ecology to better understand the deep-sea environment in the Gulf of Guinea.

  14. Global peak flux profile of proton precipitation in the equatorial zone

    International Nuclear Information System (INIS)

    Miah, M.A.

    1991-01-01

    Particle precipitation near the equator within ± 30deg geomagnetic latitude was investigated by the Phoenix-1 instrumentation on board the S81-1 mission. The monitor telescope on board the mission was sensitive to protons in the energy range 0.6-9.1 MeV, to alpha particles in the energy range 0.4-80 MeV/nucleon and Z→3 particles ( 12 C) of energy greater than 0.7 MeV/nucleon. The peak efficiency of the telescope was for particles of ∼88deg pitch angles at the line of minimum magnetic field. Careful separation of the magnetically quiet time equatorial particle data from global data coverage and subsequent analysis shows that the ML detector on board the mission detected mostly protons. The proton peak flux profile follows the line of minimum magnetic field. The full width at half maximum (FWHM) of the equatorial zone is ∼ 13deg, which is well within the EUV emission zone. (author). 14 refs., 9 figs

  15. Contribution of storm time substorms to the prompt electric field disturbances in the equatorial ionosphere

    International Nuclear Information System (INIS)

    Hui, Debrup; Chakrabarty, D.; Sekar, R.; Reeves, G. D.

    2017-01-01

    This study tries to bring out the fact that storm time substorms can compete and at times significantly contribute to the geomagnetically disturbed time prompt penetration electric field effects on low and equatorial latitudes. Observations of unusual equatorial plasma drift data from Jicamarca Unattended Long-term Investigations of the Ionosphere and Atmosphere during two space weather events show that substorms can induce both eastward and westward penetration electric fields under steady southward interplanetary magnetic field (IMF B z ) conditions. During the first event on 2 January 2005, the enhancement of the daytime eastward electric field over Jicamarca due to substorm is found to be comparable with the Sq and interplanetary electric field (IEFy) generated electric fields combined. During the second event on 19 August 2006, the substorm is seen to weaken the daytime eastward field thereby inducing a westward field in spite of the absence of northward turning of IMF B z (overshielding). The westward electric field perturbation in the absence of any overshielding events is observationally sparse and contrary to the earlier results. Further, the substorm-induced field is found to be strong enough to compete or almost nullify the effects of storm time IEFy fields. This study also shows quantitatively that at times substorm contribution to the disturbed time prompt electric fields can be significant and thus should be taken into consideration in evaluating penetration events over low latitudes.

  16. Processes of Equatorial Thermal Structure: An Analysis of Galileo Temperature Profile with 3-D Model

    Science.gov (United States)

    Majeed, T.; Waite, J. H., Jr.; Bougher, S. W.; Gladstone, G. R.

    2005-01-01

    The Jupiter Thermosphere General Circulation Model (JTGCM) calculates the global dynamical structure of Jupiter's thermosphere self-consistently with its global thermal structure and composition. The main heat source that drives the thermospheric flow is high-latitude Joule heating. A secondary source of heating is the auroral process of particle precipitation. Global simulations of Jovian thermospheric dynamics indicate strong neutral outflows from the auroral ovals with velocities up to approximately 2 kilometers per second and subsequent convergence and downwelling at the Jovian equator. Such circulation is shown to be an important process for transporting significant amounts of auroral energy to equatorial latitudes and for regulating the global heat budget in a manner consistent with the high thermospheric temperatures observed by the Galileo probe. Adiabatic compression of the neutral atmosphere resulting from downward motion is an important source of equatorial heating (less than 0.06 microbar). The adiabatic heating continues to dominate between 0.06 and 0.2 microbar, but with an addition of comparable heating due to horizontal advection induced by the meridional flow. Thermal conduction plays an important role in transporting heat down to lower altitudes (greater than 0.2microbar) where it is balanced by the cooling associated with the wind transport processes. Interestingly, we find that radiative cooling caused by H3(+), CH4, and C2H2 emissions does not play a significant role in interpreting the Galileo temperature profile.

  17. Robust increase of the equatorial Pacific rainfall and its variability in a warmed climate

    Science.gov (United States)

    Watanabe, Masahiro; Kamae, Youichi; Kimoto, Masahide

    2014-05-01

    Regional pattern of the mean precipitation changes in the latter half of the 21st century (ΔP>¯) has been interpreted in terms of mean precipitation in current climate and a magnitude of increase in mean sea surface temperature (SST). Here we use state-of-the-art climate model ensembles from the Coupled Model Intercomparison Project Phase 5 (CMIP5) and present that the amplitude of the precipitation variability, relative to slowly varying mean precipitation, coherently increases with ΔP>¯, anchored over the central equatorial Pacific where a large SST swing occurs during El Niño-Southern Oscillation (ENSO) cycles. This increase owes to skewed probability distribution of precipitation as well as an asymmetrical precipitation response to positive and negative in situ SST anomalies and is robust despite uncertainty in the future ENSO amplitude change. The CMIP5 model ensembles also give a robust estimate of the projected ΔP>¯ over the central equatorial Pacific, showing a 7% increase per unit increase of global-mean surface temperature. Observational constraints applied to the above relationship suggest that the amounts of increases in both mean precipitation and variability should be even larger than the model averages.

  18. Variabilities of mesospheric tides and equatorial electrojet strength during major stratospheric warming events

    Directory of Open Access Journals (Sweden)

    S. Sridharan

    2009-11-01

    Full Text Available The present study demonstrates the relationship between the high latitude northern hemispheric major sudden stratospheric warming (SSW events and the reversal in the afternoon equatorial electrojet (EEJ, often called the counter-electrojet (CEJ, during the winter months of 1998–1999, 2001–2002, 2003–2004 and 2005–2006. As the EEJ current system is driven by tidal winds, an investigation of tidal variabilities in the MF radar observed zonal winds during the winters of 1998–1999 and 2005–2006 at 88 km over Tirunelveli, a site close to the magnetic equator, shows that there is an enhancement of semi-diurnal tidal amplitude during the days of a major SSW event and a suppression of the same immediately after the event. The significance of the present results lies in demonstrating the latitudinal coupling between the high latitude SSW phenomenon and the equatorial ionospheric current system with clear evidence for major SSW events influencing the day-to-day variability of the CEJ.

  19. The intermediate layers and associated tidal motions observed by a digisonde in the equatorial anomaly region

    Directory of Open Access Journals (Sweden)

    C.-C. Lee

    2003-04-01

    Full Text Available This investigation presents an initial attempt to analyze a full year of daily ionosonde observations relevant to the determination of plasma densities, tidal structures, and ion transports in the equatorial anomaly region of the lower ionosphere. Particular focus is on the intermediate layers, their seasonal and diurnal variations, and cause-effect relationships. The ionogram database was recorded using a digisonde portable sounder (DPS at National Central University (NCU, 24 °58' N, 121°11' E during 1996. Statistical results indicate that the intermediate layers appear primarily during the daytime of the spring/winter months. The monthly median height characteristics reveal that the layers descend from high to low altitudes and different tidal motions control the layers in different months. Generally, the semi-diurnal and quarter-diurnal tides, which cause ionization convergence, are mainly in the spring/winter and summer/autumn months, respectively. Variations in the electron densities of the layers also indicate that the density increases could result from a great number of molecular and metallic ions. Furthermore, a novel approach to ionogram presentation is introduced to investigate the intermediate layers. This approach allows the DPS to characterize the detailed daily information of the intermediate layers.Key words. Ionosphere (equatorial ionosphere; ionosphere-atmosphere interactions; ionospheric irregularities

  20. Signatures of 3–6 day planetary waves in the equatorial mesosphere and ionosphere

    Directory of Open Access Journals (Sweden)

    B. R. Clemesha

    2006-12-01

    Full Text Available Common periodic oscillations have been observed in meteor radar measurements of the MLT winds at Cariri (7.4° S, 36.5° W and Ascension Island (7.9° S, 14.4° W and in the minimum ionospheric virtual height, h'F, measured at Fortaleza (3.9° S, 38.4° W in 2004, all located in the near equatorial region. Wavelet analysis of these time series reveals that there are 3–4-day, 6–8-day and 12–16-day oscillations in the zonal winds and h'F. The 3–4 day oscillation appeared as a form of a wave packet from 7–17 August 2004. From the wave characteristics analyzed this might be a 3.5-day Ultra Fast Kelvin wave. The 6-day oscillation in the mesosphere was prominent during the period of August to November. In the ionosphere, however, it was apparent only in November. Spectral analysis suggests that this might be a 6.5-day wave previously identified. The 3.5-day and 6.5-day waves in the ionosphere could have important roles in the initiation of equatorial spread F (plasma bubble. These waves might modulate the post-sunset E×B uplifting of the base of the F-layer via the induced lower thermosphere zonal wind and/or the E-region conductivity.

  1. Paleogene equatorial penguins challenge the proposed relationship between biogeography, diversity, and Cenozoic climate change

    Science.gov (United States)

    Clarke, Julia A.; Ksepka, Daniel T.; Stucchi, Marcelo; Urbina, Mario; Giannini, Norberto; Bertelli, Sara; Narváez, Yanina; Boyd, Clint A.

    2007-01-01

    New penguin fossils from the Eocene of Peru force a reevaluation of previous hypotheses regarding the causal role of climate change in penguin evolution. Repeatedly it has been proposed that penguins originated in high southern latitudes and arrived at equatorial regions relatively recently (e.g., 4–8 million years ago), well after the onset of latest Eocene/Oligocene global cooling and increases in polar ice volume. By contrast, new discoveries from the middle and late Eocene of Peru reveal that penguins invaded low latitudes >30 million years earlier than prior data suggested, during one of the warmest intervals of the Cenozoic. A diverse fauna includes two new species, here reported from two of the best exemplars of Paleogene penguins yet recovered. The most comprehensive phylogenetic analysis of Sphenisciformes to date, combining morphological and molecular data, places the new species outside the extant penguin radiation (crown clade: Spheniscidae) and supports two separate dispersals to equatorial (paleolatitude ≈14°S) regions during greenhouse earth conditions. One new species, Perudyptes devriesi, is among the deepest divergences within Sphenisciformes. The second, Icadyptes salasi, is the most complete giant (>1.5 m standing height) penguin yet described. Both species provide critical information on early penguin cranial osteology, trends in penguin body size, and the evolution of the penguin flipper. PMID:17601778

  2. Mechanism of seasonal eddy kinetic energy variability in the eastern equatorial Pacific Ocean

    Science.gov (United States)

    Wang, Minyang; Du, Yan; Qiu, Bo; Cheng, Xuhua; Luo, Yiyong; Chen, Xiao; Feng, Ming

    2017-04-01

    Enhanced mesoscale eddy activities or tropical instability waves (TIWs) exist along the northern front of the cold tongue in the eastern equatorial Pacific Ocean. In this study, we investigate seasonal variability of eddy kinetic energy (EKE) over this region and its associated dynamic mechanism using a global, eddy-resolving ocean general circulation model (OGCM) simulation, the equatorial mooring data, and satellite altimeter observations. The seasonal-varying enhanced EKE signals are found to expand westward from 100°W in June to 180°W in December between 0°N and 6°N. This westward expansion in EKE is closely connected to the barotropically-baroclinically unstable zonal flows that are in thermal-wind balance with the seasonal-varying thermocline trough along 4°N. By adopting an 1½-layer reduced-gravity model, we confirm that the seasonal perturbation of the thermocline trough is dominated by the anticyclonic wind stress curl forcing, which develops due to southerly winds along 4°N from June to December.

  3. Numerical experiments on the atmospheric response to cold Equatorial Pacific conditions ('La Nina') during northern summer

    International Nuclear Information System (INIS)

    Storch, H. von; Schriever, D.; Arpe, K.; Branstator, G.W.; Legnani, R.; Ulbrich, U.

    1993-01-01

    The effect of cold conditions in the central and eastern Equatorial Pacific during Northern Summer is examined in a series of numerical experiments with the low resolution (T21) atmospheric general circulation model ECHAM2. Anomalous sea surface temperatures (SST) as observed in June 1988 were prescribed and the effect on the global circulation is examined. In the model atmosphere, the anomalous cold water in the Equatorial Pacific excites a strong and stable response over the tropical Central and East Pacific. From here stationary Rossby waves radiate into both hemispheres. The Northern Hemisphere wave train is weak and affects only the Northeast Pacific area; the Southern Hemisphere wave train arches from the Central Pacific over the southern tip of South America to the South Atlantic. This response is not only present in the basic anomaly experiment with the T21 GCM but also in experiments with SST anomalies confined to the tropics and with an envelope-formulation of the SST anomalies, in experiments with a linear model, and in high resolution (T42) model experiments. The model output is also compared to the actually observed atmospheric state in June 1988. (orig./KW)

  4. Evidence and effects of a wave-driven nonlinear current in the equatorial electrojet

    Directory of Open Access Journals (Sweden)

    M. Oppenheim

    1997-07-01

    Full Text Available Ionospheric two-stream waves and gradient-drift waves nonlinearly drive a large-scale (D.C. current in the E-region ionosphere. This current flows parallel to, and with a comparable magnitude to, the fundamental Pedersen current. Evidence for the existence and magnitude of wave-driven currents derives from a theoretical understanding of E-region waves, supported by a series of nonlinear 2D simulations of two-stream waves and by data collected by rocket instruments in the equatorial electrojet. Wave-driven currents will modify the large-scale dynamics of the equatorial electrojet during highly active periods. A simple model shows how a wave-driven current appreciably reduces the horizontally flowing electron current of the electrojet. This reduction may account for the observation that type-I radar echoes almost always have a Doppler velocity close to the acoustic speed, and also for the rocket observation that electrojet regions containing gradient-drift waves do not appear also to contain horizontally propagating two-stream waves. Additionally, a simple model of a gradient-drift instability shows that wave-driven currents can cause nonsinusoidal electric fields similar to those measured in situ.

  5. Intraseasonal Variability of the Equatorial Indian Ocean Observed from Sea Surface Height, Wind, and Temperature Data

    Science.gov (United States)

    Fu, Lee-Lueng

    2007-01-01

    The forcing of the equatorial Indian Ocean by the highly periodic monsoon wind cycle creates many interesting intraseasonal variabilities. The frequency spectrum of the wind stress observations from the European Remote Sensing Satellite scatterometers reveals peaks at the seasonal cycle and its higher harmonics at 180, 120, 90, and 75 days. The observations of sea surface height (SSH) from the Jason and Ocean Topography Experiment (TOPEX)/Poseidon radar altimeters are analyzed to study the ocean's response. The focus of the study is on the intraseasonal periods shorter than the annual period. The semiannual SSH variability is characterized by a basin mode involving Rossby waves and Kelvin waves traveling back and forth in the equatorial Indian Ocean between 10(deg)S and 10(deg)N. However, the interference of these waves with each other masks the appearance of individual Kelvin and Rossby waves, leading to a nodal point (amphidrome) of phase propagation on the equator at the center of the basin. The characteristics of the mode correspond to a resonance of the basin according to theoretical models. The theory also calls for similar modes at 90 and 60 days.

  6. HF radar observations of equatorial spread-F over West Africa

    Directory of Open Access Journals (Sweden)

    J.-F. Cécile

    Full Text Available New experimental data depicting equatorial spread-F were taken during an HF radar sounding campaign in Korhogo (Ivory Coast, 9°24N, 5°37W, dip 4°S. Range-time-intensity maps of the radar echoes have been analyzed to identify the signatures of density depletions and bottomside spread-F. Density depletions are well known features of equatorial spread-F, and are believed to emerge after the development of a Rayleigh-Taylor instability on the bottomside F-layer. A simple model is developed and used to simulate the flow of density depletions over the radar field of view. The simulation permits an interpretation of the data that yields the zonal flow velocity as a function of local time. Comparisons with previous measurements are undertaken to assess the consistency of the computational results, and qualitative arguments are presented to identify bottomside spread-F. Using the computational results as reference, a morphological study of ionograms showing spread-F is undertaken which reveals the specific signature of bottomside spread-F on ionograms recorded just after sunset.

  7. HF radar observations of equatorial spread-F over West Africa

    Directory of Open Access Journals (Sweden)

    J.-F. Cécile

    1996-04-01

    Full Text Available New experimental data depicting equatorial spread-F were taken during an HF radar sounding campaign in Korhogo (Ivory Coast, 9°24N, 5°37W, dip 4°S. Range-time-intensity maps of the radar echoes have been analyzed to identify the signatures of density depletions and bottomside spread-F. Density depletions are well known features of equatorial spread-F, and are believed to emerge after the development of a Rayleigh-Taylor instability on the bottomside F-layer. A simple model is developed and used to simulate the flow of density depletions over the radar field of view. The simulation permits an interpretation of the data that yields the zonal flow velocity as a function of local time. Comparisons with previous measurements are undertaken to assess the consistency of the computational results, and qualitative arguments are presented to identify bottomside spread-F. Using the computational results as reference, a morphological study of ionograms showing spread-F is undertaken which reveals the specific signature of bottomside spread-F on ionograms recorded just after sunset.

  8. Ligand identification using electron-density map correlations

    International Nuclear Information System (INIS)

    Terwilliger, Thomas C.; Adams, Paul D.; Moriarty, Nigel W.; Cohn, Judith D.

    2007-01-01

    An automated ligand-fitting procedure is applied to (F o − F c )exp(iϕ c ) difference density for 200 commonly found ligands from macromolecular structures in the Protein Data Bank to identify ligands from density maps. A procedure for the identification of ligands bound in crystal structures of macromolecules is described. Two characteristics of the density corresponding to a ligand are used in the identification procedure. One is the correlation of the ligand density with each of a set of test ligands after optimization of the fit of that ligand to the density. The other is the correlation of a fingerprint of the density with the fingerprint of model density for each possible ligand. The fingerprints consist of an ordered list of correlations of each the test ligands with the density. The two characteristics are scored using a Z-score approach in which the correlations are normalized to the mean and standard deviation of correlations found for a variety of mismatched ligand-density pairs, so that the Z scores are related to the probability of observing a particular value of the correlation by chance. The procedure was tested with a set of 200 of the most commonly found ligands in the Protein Data Bank, collectively representing 57% of all ligands in the Protein Data Bank. Using a combination of these two characteristics of ligand density, ranked lists of ligand identifications were made for representative (F o − F c )exp(iϕ c ) difference density from entries in the Protein Data Bank. In 48% of the 200 cases, the correct ligand was at the top of the ranked list of ligands. This approach may be useful in identification of unknown ligands in new macromolecular structures as well as in the identification of which ligands in a mixture have bound to a macromolecule

  9. Spatio-temporal evolutions of non-orthogonal equatorial wave modes derived from observations

    Science.gov (United States)

    Barton, Cory

    Equatorial waves have been studied extensively due to their importance to the tropical climate and weather systems. Historically, their activity is diagnosed mainly in the wavenumber-frequency domain. Recently, many studies have projected observational data onto parabolic cylinder functions (PCFs), which represent the meridional structure of individual wave modes, to attain time-dependent spatial wave structures. The non-orthogonality of wave modes has yet posed a problem when attempting to separate data into wave fields where the waves project onto the same structure functions. We propose the development and application of a new methodology for equatorial wave expansion of instantaneous flows using the full equatorial wave spectrum. By creating a mapping from the meridional structure function amplitudes to the equatorial wave class amplitudes, we are able to diagnose instantaneous wave fields and determine their evolution. Because all meridional modes are shared by some subset of the wave classes, we require constraints on the wave class amplitudes to yield a closed system with a unique solution for all waves' spatial structures, including IG waves. A synthetic field is analyzed using this method to determine its accuracy for data of a single vertical mode. The wave class spectra diagnosed using this method successfully match the correct dispersion curves even if the incorrect depth is chosen for the spatial decomposition. In the case of more than one depth scale, waves with varying equivalent depth may be similarly identified using the dispersion curves. The primary vertical mode is the 200 m equivalent depth mode, which is that of the peak projection response. A distinct spectral power peak along the Kelvin wave dispersion curve for this value validates our choice of equivalent depth, although the possibility of depth varying with time and height is explored. The wave class spectra diagnosed assuming this depth scale mostly match their expected dispersion curves

  10. Characteristic molecular vibrations of adenosine receptor ligands.

    Science.gov (United States)

    Chee, Hyun Keun; Yang, Jin-San; Joung, Je-Gun; Zhang, Byoung-Tak; Oh, S June

    2015-02-13

    Although the regulation of membrane receptor activation is known to be crucial for molecular signal transduction, the molecular mechanism underlying receptor activation is not fully elucidated. Here we study the physicochemical nature of membrane receptor behavior by investigating the characteristic molecular vibrations of receptor ligands using computational chemistry and informatics methods. By using information gain, t-tests, and support vector machines, we have identified highly informative features of adenosine receptor (AdoR) ligand and corresponding functional amino acid residues such as Asn (6.55) of AdoR that has informative significance and is indispensable for ligand recognition of AdoRs. These findings may provide new perspectives and insights into the fundamental mechanism of class A G protein-coupled receptor activation. Copyright © 2015 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

  11. Effects of PPARγ Ligands on Leukemia

    Directory of Open Access Journals (Sweden)

    Yoko Tabe

    2012-01-01

    Full Text Available Peroxisome proliferator-activated receptors (PPARs and retinoic acid receptors (RARs, members of the nuclear receptor superfamily, are transcription factors that regulate a variety of important cellular functions. PPARs form heterodimers retinoid X receptor (RXR, an obligate heterodimeric partner for other nuclear receptors. Several novel links between retinoid metabolism and PPAR responses have been identified, and activation of PPAR/RXR expression has been shown to increase response to retinoids. PPARγ has emerged as a key regulator of cell growth and survival, whose activity is modulated by a number of synthetic and natural ligands. While clinical trials in cancer patients with thiazolidinediones (TZD have been disappointing, novel structurally different PPARγ ligands, including triterpenoids, have entered clinical arena as therapeutic agents for epithelial and hematopoietic malignancies. Here we shall review the antitumor advances of PPARγ, alone and in combination with RARα ligands in control of cell proliferation, differentiation, and apoptosis and their potential therapeutic applications in hematological malignancies.

  12. Assessment of Ionospheric Spatial Decorrelation for CAT I GBAS in Equatorial Region at Nominal days: Data Selection and Bias Removal

    Science.gov (United States)

    Chang, H.; Lee, J.

    2017-12-01

    Ground-based augmentations of global positioning system (GBAS) provide the user with the integrity parameter, standard deviation of vertical ionospheric gradient (σvig), to ensure integrity. σvig value currently available in CAT I GBAS is derived from the data collected from the reference stations located on the US mainland and have a value of 4 mm/km. However, since the equatorial region near the geomagnetic equator is relatively more active in the ionosphere than the mid-latitude region, there is a limit to applying σvig used in the mid-latitude region on the equatorial region. Also, since the ionospheric phenomena of daytime and nighttime in the equatorial region are significantly different, it is necessary to apply σvig whilst distinguishing the time zone. This study presents a method for obtaining standard deviation of vertical ionospheric gradient in the equatorial region at nominal days considering the equatorial ionosphere environment. We used the data collected from the Brazilian region near the geomagnetic equator in the nominal days. One of the distinguishing features of the equatorial ionosphere environment from the mid-latitude ionosphere environment is that the scintillation event occurs frequently. Therefore, the days used for the analysis were selected not only by geomagnetic indexes Kp (Planetary K index) and Dst (Disturbance storm index), but also by S4 (Scintillation index) which indicates scintillation event. In addition, unlike the ionospheric delay bias elimination method used in the mid-latitude region, the `Long-term ionospheric anomaly monitor (LTIAM)' used in this study utilized the bias removal method that applies different bias removal standards according to IPP (Ionospheric pierce point) distance in consideration of ionospheric activity. As a result, σvig values which are conservative enough to bound ionosphere spatial decorrelation for the equatorial region in nominal days are 8 mm/km for daytime and 19 mm/km for nighttime

  13. Fasting insulin has a stronger association with an adverse cardiometabolic risk profile than insulin resistance: the RISC study

    DEFF Research Database (Denmark)

    de Rooij, Susanne R; Dekker, Jacqueline M; Kozakova, Michaela

    2009-01-01

    OBJECTIVE: Fasting insulin concentrations are often used as a surrogate measure of insulin resistance. We investigated the relative contributions of fasting insulin and insulin resistance to cardiometabolic risk and preclinical atherosclerosis. DESIGN AND METHODS: The Relationship between Insulin...... insulin, a simple and practical measure, may be a stronger and independent contributor to cardiometabolic risk and atherosclerosis in a healthy population than hyperinsulinemic euglycemic clamp-derived insulin sensitivity.......OBJECTIVE: Fasting insulin concentrations are often used as a surrogate measure of insulin resistance. We investigated the relative contributions of fasting insulin and insulin resistance to cardiometabolic risk and preclinical atherosclerosis. DESIGN AND METHODS: The Relationship between Insulin...... of the metabolic syndrome in 1177 participants. Carotid artery intima media thickness (IMT) was measured by ultrasound to assess preclinical atherosclerosis. RESULTS: Fasting insulin was correlated with all elements of the metabolic syndrome. Insulin sensitivity (M/I) was correlated with most elements. The odds...

  14. Collective Nostalgia Is Associated With Stronger Outgroup-Directed Anger and Participation in Ingroup-Favoring Collective Action

    Directory of Open Access Journals (Sweden)

    Wing-Yee Cheung

    2017-08-01

    Full Text Available Collective nostalgia refers to longing for the way society used to be. We tested whether collective nostalgia is associated with ingroup-favoring collective action and whether this association is mediated by outgroup-directed anger and outgroup-directed contempt. We conducted an online study of Hong Kong residents (N = 111 during a large-scale democratic social movement, the Umbrella Movement, that took place in Hong Kong in 2014 in response to proposed electoral reforms by the Chinese government in Mainland China. Reported collective nostalgia for Hong Kong’s past was high in our sample and collective nostalgia predicted stronger involvement in ingroup-favoring collective action, and it did so indirectly via higher intensity of outgroup-directed anger (but not through outgroup-directed contempt. We argue that collective nostalgia has implications for strengthening ingroup-serving collective action, and we highlight the importance of arousal of group-based emotions in this process.

  15. Rhodium, iridium and nickel complexes with a 1,3,5-triphenylbenzene tris-MIC ligand. Study of the electronic properties and catalytic activities

    Directory of Open Access Journals (Sweden)

    Carmen Mejuto

    2015-12-01

    Full Text Available The coordination versatility of a 1,3,5-triphenylbenzene-tris-mesoionic carbene ligand is illustrated by the preparation of complexes with three different metals: rhodium, iridium and nickel. The rhodium and iridium complexes contained the [MCl(COD] fragments, while the nickel compound contained [NiCpCl]. The preparation of the tris-MIC (MIC = mesoionic carbene complex with three [IrCl(CO2] fragments, allowed the estimation of the Tolman electronic parameter (TEP for the ligand, which was compared with the TEP value for a related 1,3,5-triphenylbenzene-tris-NHC ligand. The electronic properties of the tris-MIC ligand were studied by cyclic voltammetry measurements. In all cases, the tris-MIC ligand showed a stronger electron-donating character than the corresponding NHC-based ligands. The catalytic activity of the tri-rhodium complex was tested in the addition reaction of arylboronic acids to α,β-unsaturated ketones.

  16. Elite level rhythmic gymnasts have significantly more and stronger pain than peers of similar age: a prospective study.

    Science.gov (United States)

    Sabeti, Manuel; Jeremian, Lusine; Graf, Alexandra; Kandelhart, Robert

    2015-01-01

    Rhythmic gymnastics (RG) unites aesthetic, ballet-like motion, and all aspects of gymnastics. To reach elite level, girls begin at early age the intensive training. To date it is unclear if such demanding training influences the incidence and intensity of painful overuse injuries. The purpose of this study is to analyze anatomical painful regions and pain intensity in elite level rhythmic gymnasts (elRG) and compare results with an age-matched control group (CG). This prospective field study was carried out at the European Championship in RG 2013 (218 participating athletes, Vienna, Austria). Volunteering athletes were interviewed according to a preformed questionnaire. As CG secondary school pupils without any competitive sports experience were analyzed accordingly. Overall, 243 young females (144 elRG/66 % of all participants and 99 CG) were observed. ElRGs were significantly (s.) smaller, lighter, and had s. stronger pain (p < 0.001). A total of 72 % of athletes reported to have at least one painful body region compared with 52 % of CG (p < 0.001). ElRG had nearly three times more serious injuries than the CG. In all 23 % off all elRG reported to have had no access to professional medical care. ElRGs were s. more frequently (25 vs 9 %) affected at the lumbar spine and the ankle joint (17.4 vs 7 %). To our knowledge, this trial analyzes the largest cohort of elRG to date. Hence, it is clearly alluded that intensive training in RG is a significant factor causing more and stronger pain than in a CG.

  17. Provenance and supply of Fe-enriched terrigenous sediments in the western equatorial Pacific and their relation to precipitation variations during the late Quaternary

    NARCIS (Netherlands)

    Wu, J.W.; Liu, Z.; Zhou, nn.

    2013-01-01

    Iron (Fe) deposition in the equatorial Pacific has important implications for the global carbon cycle, while the provenance of Fe supply and its change remain highly debated. Here, we geochemically characterize the provenance of terrigenous sediments deposited on the pathways of the Equatorial

  18. Two fac-tricarbonylrhenium(I) azadipyrromethene (ADPM) complexes: ligand-substitution effect on crystal structure.

    Science.gov (United States)

    Cibian, Mihaela; Bessette, André; O'Connor, Andrew; Ferreira, Janaina G; Hanan, Garry S

    2015-02-01

    The crystal structures of fac-(acetonitrile-κN)(2-{[3,5-bis(4-methoxyphenyl)-2H-pyrrol-2-ylidene-κN(1)]amino}-3,5-bis(4-methoxyphenyl)-1H-pyrrol-1-ido-κN(1))tricarbonylrhenium(I)-hexane-acetonitrile (2/1/2), [Re(C36H30N3O4)(CH3CN)(CO)3]·0.5C6H14·CH3CN, (2), and fac-(2-{[3,5-bis(4-methoxyphenyl)-2H-pyrrol-2-ylidene-κN(1)]amino}-3,5-bis(4-methoxyphenyl)-1H-pyrrol-1-ido-κN(1))tricarbonyl(dimethyl sulfoxide-κO)rhenium(I), [Re(C36H30N3O4)(C2H6OS)(CO)3], (3), at 150 K are reported. Both complexes display a distorted octahedral geometry, with a fac-Re(CO)3 arrangement and one azadipyrromethene (ADPM) chelating ligand in the equatorial position. One solvent molecule completes the coordination sphere of the Re(I) centre in the remaining axial position. The ADPM ligand shows high flexibility upon coordination, while retaining its π-delocalized nature. Bond length and angle analyses indicate that the differences in the geometry around the Re(I) centre in (2) and (3), and those found in three reported fac-Re(CO)3-ADPM complexes, are dictated mainly by steric factors and crystal packing. Both structures display intramolecular C-H...N hydrogen bonding. Intermolecular interactions of the Csp(2)-H...π and Csp(2)-H...O(carbonyl) types link the discrete monomers into extended chains.

  19. Ligand assisted carbon dioxide activation and hydrogenation using molybdenum and tungsten amides.

    Science.gov (United States)

    Chakraborty, Subrata; Blacque, Olivier; Berke, Heinz

    2015-04-14

    The hepta-coordinated isomeric M(NO)Cl3(PN(H)P) complexes {M = Mo, ; W, , PN(H)P = (iPr2PCH2CH2)2NH, (HN atom of PN(H)P syn and anti to the NO ligand)} and the paramagnetic species M(NO)Cl2(PN(H)P) (M = Mo, ; W, ) could be prepared via a new synthetic pathway. The pseudo trigonal bipyramidal amides M(NO)(CO)(PNP) {M = Mo, ; W, ; [PNP](-) = [(iPr2PCH2CH2)2N](-)} were reacted with CO2 at room temperature with CO2 approaching the M[double bond, length as m-dash]N double bond in the equatorial (CO,NO,N) plane trans to the NO ligand and forming the pseudo-octahedral cyclic carbamates M(NO)(CO)(PNP)(OCO) (M = Mo, ; W = ). DFT calculations revealed that the approach to form the isomer is kinetically determined. The amine hydrides M(NO)H(CO)(PN(H)P) {M = Mo, ; W, }, obtained by H2 addition to , insert CO2 (2 bar) at room temperature into the M-H bond generating isomeric mixtures of the η(1)-formato complexes M(NO)(CO)(PN(H)P)(η(1)-OCHO), (M = Mo, ; M = W, ). Closing the stoichiometric cycles for sodium formate formation the isomeric mixtures were reacted with 1 equiv. of Na[N(SiMe3)2] regenerating . Attempts to turn the stoichiometric formate production into catalytic CO2 hydrogenation using in the presence of various types of sterically congested bases furnished yields of formate salts of up to 4%.

  20. Ligand Exchange and 1H NMR Quantification of Single- and Mixed-Moiety Thiolated Ligand Shells on Gold Nanoparticles.

    Science.gov (United States)

    Smith, Ashley M; Millstone, Jill E

    2017-01-01

    The use of nanoparticles in biomedicine critically depends on their surface chemistry. For metal nanoparticles, a common way to tune this surface chemistry is through mass action ligand exchange, where ligand exchange can be used to expand the functionality of the resulting nanoparticle conjugates. Specifically, the quantity, identity, and arrangement of the molecules in the resulting ligand shell each can be tuned significantly. Here, we describe methods to exchange and quantify thiolated and non-thiolated ligands on gold nanoparticle surfaces. Importantly, these strategies allow the quantification of multiple ligand types within a single ligand shell, simultaneously providing ligand composition and ligand density information. These results are crucial for both designing and assigning structure-function relationships in bio-functionalized nanoparticles, and these methods can be applied to a broad range of nanoparticle cores and ligand types including peptides, small molecule drugs, and oligonucleotides.