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Sample records for asmari formation zagros

  1. Facies analysis and depositional environments of the OligoceneeMiocene Asmari Formation, Zagros Basin, Iran

    Institute of Scientific and Technical Information of China (English)

    Mohammad Sahraeyan; Mohammad Bahrami; Solmaz Arzaghi

    2014-01-01

    The Asmari Formation (a giant hydrocarbon reservoir) is a thick carbonate sequence of the Oligocenee Miocene in the Zagros Basin, southwest of Iran. This formation is exposed at Tang-e-Lendeh in the Fars interior zone with a thickness of 190 m comprising medium and thick to massive bedded carbonates. The age of the Asmari Formation in the study area is the late Oligocene (Chattian)eearly Miocene (Burdigalian). Ten microfacies are defined, characterizing a gradual shallowing upward trend;the related environments are as follows:open marine (MF 8e10), restricted lagoon (MF 6e7), shoal (MF 3e5), lagoon (MF 2), and tidal flat (MF 1). Based on the environmental interpretations, a homoclinal ramp consisting of inner and middle parts prevails. MF 3e7 are characterized by the occurrence of large and small porcelaneous benthic foraminifera representing a shallow-water setting of an inner ramp, influenced by wave and tidal pro-cesses. MF 8e10, with large particles of coral and algae, represent a deeper fair weather wave base of a middle ramp setting.

  2. The Stratigraphy of the Aquitanian-Burdigalian Asmari Formation of Lorestan Sub-Basin, Iran: an Inclusive Study

    Science.gov (United States)

    Lankarani, M.; Amini, A.; Swennen, R.

    2012-04-01

    The Asmari Formation is the most important hydrocarbon reservoir in the oilfields of the Zagros pro-foreland basin. The shallow carbonates of this formation have been producing oil for nearly one century. However, detailed stratigraphic aspects of this significant rock unit in some parts of the basin, especially Lorestan sub-basin, are poorly studied. So, because of the necessity, several outcrops of the Asmari Formation in this region were inclusively studied in the framework of this project. The Lorestan sub-basin is a narrow, northwest-southeast trending intrashelf depression in the Zagros basin which is created during the Mesozoic. By the end of Mesozoic, continental collision between Iran and Arabian plates resulted in the formation of the Zagros fold-thrust belt and its associated pro-foreland basin, in which the Asmari Formation was deposited. Detailed paleontological investigations done by this study (based on the distribution of the index fossils) showed that age range of the Asmari Formation in this region is Aquitanian-Burdigalian. The main grain associations forming the facies of the formation were found rhodoliths, large benthic foraminifera (rotaliids), green algae, bivalves (mostly oysters), bryozoans, and echinoderms. The biotic associations suggest that carbonate sedimentation took place in tropical waters under oligotrophic conditions. This Aquitanian-Burdigalian carbonate deposits, which were deposited on an oligotrophic tropical carbonate ramp developed in a foredeep tectonic setting, have unconformable boundaries with the overlying and underlying formations. Comprehensive sequence stratigraphic investigations proved that deposition of the Asmari Formation in the studied region has been generally coincident with a transgressive event during the time of global second order sea-level highstand. So, the whole Asmari rock unit in the Lorestan sub-basin comprises a supersequence formed as a result of the second-order eustatic sea-level changes

  3. Controlling factors on the reservoir quality of the Asmari Formation: A case study from the Dezful Embayment

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    Mehdi Daraei

    2015-10-01

    Full Text Available Material & Methods   The study is based on sedimentological and petrophysical data from two wells of a field located in the Dezful Embayment, where the Ahwaz Sandstone Member is present, alongside with some compar able sedimentological data from NW Zagros, where the Kalhur Evaporitic Member is extended. A total of 600 red-stained thin sections, 198 blue-dyed thin sections, and 908 poroperm values were the main data included in this study .     Discussion of Results & Conclusions   Facies analysis shows the Asmari Formation in the studied area is composed of 11 facies, representing three depositional systems. Most of the area was occupied by a carbonate depositional system with a ramp physiography. Meanwhile, in SW Zagros, a marginal marine deltaic system prevailed, and in NW Zagros a tectonically driven evaporitic intrashelf sub-basin was created by a combination of arid climatic condition, sea-level fluctuations and tectonics. In these two sub-basins, the deposition of Ahwaz Sandstone Member and Kalhure Evaporitic Member occurred, respectively.   Based on the findings, the main diagenetic processes affecting the Asmari Formation are micritization, dolomitization, dissolution, cementation, compaction, and minor fracturing. Micritization is a common process in the shoal and lagoonal facies, leading to a more susceptible facies to the later dolomitization. Dolomitization is the most pervasive diagenetic process of the formation, most of which occurred due to early diagenetic evaporative models (seepage-reflux and sabkha dolomitizations. Dissolution is another early diagenetic event in the strata, which probably happened by evaporitic brines. This process has dominantly produced moldic pores in the formation. Cementation as the main porosity destruction process has taken place in variable mineralogies and fabrics. Dolomite cement is the most widespread cement, precipitated in early diagenesis. Anhydrite cement is the more effective cementation

  4. Fracture characterization by fusion of geophysical and geomechanical data: a case study from the Asmari reservoir, the Central Zagros fold-thrust belt

    International Nuclear Information System (INIS)

    Fractured reservoirs contain a large proportion of hydrocarbon reserves in the Middle East. In these types of reservoirs, a variety of fracture types and networks provide the required permeability for hydrocarbon storage and flow. Fractured reservoir characterization has been challenging to petroleum geoscientists and reservoir engineers in terms of developing new approaches in this direction. A variety of techniques have been developed in the literature to study the distribution and the impact of fracture pore types on reservoir characterization. However, such techniques are not suitable for subsurface cases where prediction of fractures become troublesome and each of the developed techniques has its own advantages and limitations. In this study, an integrated approach is proposed for fracture characterization by employing different sources of data including 3D seismic attributes, geomechanical parameters, unconventional logs (image log and nuclear magnetic response (NMR) log), velocity-deviation log (VDL), conventional well logs, and routine core analysis data. Based on the azimuths of horizontal principal stresses and natural fractures, location of the wells over the structure hanging wall is determined. Interpretation of the seismic profiles from the study area indicated a fault-related fold structure style with fault throws controlling the magnitude of curvature. Moreover, fracture distribution of the Asmari reservoir is predicted by using curvature attribute, geomechanical parameters and horizontal slices of VDL. It seems that fractures probably have a much higher distribution at zone 1 and zone 3 of the Asmari formation. (paper)

  5. Fracture characterization by fusion of geophysical and geomechanical data: a case study from the Asmari reservoir, the Central Zagros fold-thrust belt

    Science.gov (United States)

    Kosari, Ehsan; Ghareh-Cheloo, Sajjad; Kadkhodaie-Ilkhchi, Ali; Bahroudi, Abbas

    2015-02-01

    Fractured reservoirs contain a large proportion of hydrocarbon reserves in the Middle East. In these types of reservoirs, a variety of fracture types and networks provide the required permeability for hydrocarbon storage and flow. Fractured reservoir characterization has been challenging to petroleum geoscientists and reservoir engineers in terms of developing new approaches in this direction. A variety of techniques have been developed in the literature to study the distribution and the impact of fracture pore types on reservoir characterization. However, such techniques are not suitable for subsurface cases where prediction of fractures become troublesome and each of the developed techniques has its own advantages and limitations. In this study, an integrated approach is proposed for fracture characterization by employing different sources of data including 3D seismic attributes, geomechanical parameters, unconventional logs (image log and nuclear magnetic response (NMR) log), velocity-deviation log (VDL), conventional well logs, and routine core analysis data. Based on the azimuths of horizontal principal stresses and natural fractures, location of the wells over the structure hanging wall is determined. Interpretation of the seismic profiles from the study area indicated a fault-related fold structure style with fault throws controlling the magnitude of curvature. Moreover, fracture distribution of the Asmari reservoir is predicted by using curvature attribute, geomechanical parameters and horizontal slices of VDL. It seems that fractures probably have a much higher distribution at zone 1 and zone 3 of the Asmari formation.

  6. Determination of density pattern of fracture in Asmari Formation in Marun oilfield

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    Kheyrollah Noraeinezhad

    2015-05-01

    Full Text Available Marun oilfield is located in the middle part of Dezful Embayment and is situated along the Aghajari, Ahvaz and Ramin anticline. Given the important role of fracture characteristics for improving production, so the aim of this research is to investigate the density pattern of fracture in Asmari formation in Marun oilfield. For this purpose, results of image log, core data, graphic well log, methods of inscribed circle analysis and curvature changes geometry of anticline were analyzed. Asmari formation is the main reservoir rock in Marun oilfield that divided into five zones. Limestone and dolomite are the main lithology of zones 1, 2 and 3 which has a high density of fractures (especially in zones with 90% dolomite. Also there is less fracture density (micro fracture in the 4 and 5 Asmari zone due to an increase of shale and marl layers and due to less break ablity has a less distribution of fractures. The result show that there are a good conformity existed between the results of inscribed circle analysis, image log, core data, curvature and the presence of fractures in Marun anticline. The data indicate that highest density of fracture density concentrates in the southern limb in the central region of anticline and also in the north limb in the northeast region of the anticline. So, finally using these parameters, it is recommended that further development and production wells be drilled in the north eastern part of the oil filed as well as center part of southern flank of the anticline.

  7. Biostratigraphy of the Gurpi Formation in Zagros Basin, Iran

    Directory of Open Access Journals (Sweden)

    2015-10-01

    Full Text Available Introdaction   The Gurpi Formation is developed in the central of the Zagros fold in Khuzestan, Lorestan and Fars provinces of southwestern Iran, defined az theZagros basin ,The Gurpi refers to Gurpi Mountain in the Kuzestan province.type section gurpi,which is N of the Lali oil wells and N-E of Masjed – Soleiman city,comprises 320m argillaceous limestone and gry-to-blueshale marl(James and Wynd,1965Although the boundary the Gurpi Formation and the underlying Ilam Formation is reported to be gradual,the altered facies found at this boundrary could be a sign of a low disconformity or even unconformity.In some place,the Ilam Formation does not exist and tne Gurpi Formation lie abave the Sarvak Formation.The upper boundry of the Gurpi Formation is more noticeable and there are different overlying formations.In Khozstan province,the Gurpi Formation is overlain by purplr shale of pabdeh Formation with signs of unconformity.The Gurpi Formation is not always concurrent. Biostratigraphy and lithological characteries of the Gurpi Formation were studied by James and Wynd (1965, Taheri (1998, KameliAzao (2002, Zarei (2005, Hematinasab (2008, Madavian (2009, Tavalaian (2011. This research study aims at describing the biostratigraphy of Gurpi Formation.In this study five stratigraphic section is investigate for its Planktonc Foraminiforal content.     Method and Matrials   This study involves five stratigraphic sections from the Gurpi Formation that were measured the ticknes and determind of Litostratigrapic limit as well as recognizd of detail litostrstigray the Gurpi Formation.More than 525 thine sections were examined. Some samples from the underlying Pabdeh Formation were also analysed for comparison. then recognizd Genus and species of Planktonic foraminifera and biozones mentioned wells have been introduced. In order to the biozonation of Gurpi Formation, stratigraphic distribution of well- known foraminifora is recognizd and then biozones are

  8. Benthic foraminifera as biostratigraphical and paleoecological indicators:An example from Oligo-Miocene deposits in the SW of Zagros basin, Iran

    Institute of Scientific and Technical Information of China (English)

    Asghar Roozpeykar; Iraj Maghfouri Moghaddam

    2016-01-01

    The Asmari Formation is a predominantly carbonate lithostratigraphic unit that outcrops in the Zagros Basin. Micropaleontological studies of the Asmari Formation in the Dehdasht area led to the identifi-cation of 51 species of foraminifera taxa. Among the foraminifera, Nummulites cf. vascus, Operculin sp., Operculina complanata, Eulepidina dilatata, Eulepidina elephantine, Ditrupa sp., Miogypsina sp., Elphidium sp. 14, and Borelis melo curdica are the most important. The Lepidocyclina-Operculina-Ditrupa assemblage zone represents the RupelianeChattian age. The Aquitanian age is also defined by co-occurrence of Miogypsina sp. and Elphidium sp. 14, and finally, the first occurrence of Borelis melo curdica represents the Burdigalian. Based on faunal assemblages, the following paleoenvironmental settings are determined for the deposition of the study section: (1) the deep, offshore settings in the aphotic zone dominated by pelagic and small benthic foraminifera;(2) the low energy, turbid and low light parts of the oligophotic zone characterized by large and flat lepidocyclinids (Eulepidina) and Nummulitidae;(3) the low turbidity, deeper part of the inner ramp dominated by Miogypsinoides, Neorotalia, Lepidocyclina, Operculina and Archias; (4) the shallow, marginal marine environment exposed to salinity fluctuations (short-term salinity fluctuations or fully marine conditions) dominated by small benthic Foraminifera (Ammonia and Elphidium); (5) highly translucent, shallowest part of the inner ramp dominated by representatives of Borelis, Meandropsina and Peneroplis. The biotic assemblages represent warm tropical waters with oligotrophic to slightly mesotrophic conditions.

  9. Crustal scale geometry of the Zagros fold–thrust belt, Iran

    OpenAIRE

    McQuarrie, Nadine

    2004-01-01

    Balanced cross-sections across the Zagros fold–thrust belt in Iran are used to analyze the geometry of deformation within the sedimentary cover rocks, and to test the hypothesis of basement involved thrusting throughout the fold–thrust belt. Although the Zagros deformation front is a relatively rectilinear feature, the sinuous map-view morphology of the mountain front is a result of a 6 km structural step in the regional elevation of the Asmari Limestone that produces a pronounced step in top...

  10. Imagerie sismique de structures pétrolières plissées et faillées du Zagros (Iran), à partir de données de surface et de puits

    OpenAIRE

    Kazemi, Kazem

    2009-01-01

    Le Champ d'Aghajari est situé dans le Dezful, une des zones du Zagros structurée par d'importantes failles de charriage, et contenant la majeure partie des champs d'huile iraniens. La formation calcaire de l'Asmari, datant de la fin Oligocène à début Miocène, constitue l'une des principales couches réservoir du Sud-Ouest de l'Iran, avec un historique de production de plus d'un demi siècle pour plusieurs champs de cette région. L'objectif de cette thèse est de mieux comprendre la structure de ...

  11. Lithological and petrophysical evaluation of the caprock keybeds, Asmari Reservoir of Pazanan Oil Field, Zagros, Iran

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    Bahman Soleimani

    2010-01-01

    Full Text Available The Pazanan oil field is located 150 km SE of ahvaz city in SW of Iran and measures 60 km long, 4-6 km wide. The caprock of this oil field were evaluated using well logs (gamma-ray and sonic logs SEM and petrographical microscopy data. The cap rock consist of mudstone, interlayers of anhydrite and bitumens shale. Therefore, it can be classified as mudstone type. On the basis of our investigations, the Caprock can be divided in to 6 keybeds: A(Anhydrite, B(Bitumenshale & some times bitumen marls, C (mudstone with interlayers of shale & anhydrite, D (mudstone & anhydrite, E (mudstone& F(mudstone & packstone, almost all of these units coverd by salt. Anhydrite beds show the following textures: microlitic, spherolite, porphyroblast, and granular. Anhydrite crystals indicate the occurrence of processes such as emplacement and calcitization. Sonic and gamma-ray well logs were used to determine lithological changes. The highest peak is correlated with mudstone units. Caprock depth varies from 2580m(min-2717m(max [northern part], 1704(min. - 2444(max. [central part],And 2050 (min.- 2490 (max. [southern part] using well drilling data. It seems that that the thickness in the southern part is less than is other part. Comparing the thicknesses of different keybeds. The maximum occurs in the c-keybeds. The sedimentar : sequence of Caprock started by mudstone, packstone and interlayers of anhydrite, followed by mudstone, anhydrite, shale-marl, as well as bitumen shale, mudstone and anhydrite and finally was overlaid by salt. Lithological variation indicate a sabkha-lacustrine environment. Therefore, the hot-wet and hot-dry climate was dominated. In some cases, Caprock thickness decreases to 6m without any gap. This thinning is related to structural deformation. Unfavorable lithologyconditions resulted is well collaps.

  12. Hydrothermal dolomitization of the Bekhme formation (Upper Cretaceous), Zagros Basin, Kurdistan Region of Iraq: Record of oil migration and degradation

    Science.gov (United States)

    Mansurbeg, Howri; Morad, Daniel; Othman, Rushdy; Morad, Sadoon; Ceriani, Andrea; Al-Aasm, Ihsan; Kolo, Kamal; Spirov, Pavel; Proust, Jean Noel; Preat, Alain; Koyi, Hemin

    2016-07-01

    The common presence of oil seepages in dolostones is widespread in Cretaceous carbonate successions of the Kurdistan Region of Iraq. This integrated field, petrographic, chemical, stable C, O and Sr isotopes, and fluid inclusion study aims to link dolomitization to the origin and geochemical evolution of fluids and oil migration in the Upper Cretaceous Bekhme carbonates. Flux of hot basinal (hydrothermal) brines, which is suggested to have occurred during the Zagros Orogeny, resulted in dolomitization and cementation of vugs and fractures by coarse-crystalline saddle dolomite, equant calcite and anhydrite. The saddle dolomite and host dolostones have similar stable isotopic composition and formed prior to oil migration from hot (81-115 °C) basinal NaCl-MgCl2-H2O brines with salinities of 18-22 wt.% NaCl eq. The equant calcite cement, which surrounds and hence postdates saddle dolomite, has precipitated during oil migration from cooler (60-110 °C) NaCl-CaCl2-H2O brines (14-18 wt.% NaCl eq). The yellowish fluorescence color of oil inclusions in the equant calcite indicates that the oil had API gravity of 15-25° composition, which is lighter than present-day oil in the reservoirs (API of 10-17°). This difference in oil composition is attributed to oil degradation by the flux of meteoric water, which is evidenced by the low δ13C values (- 8.5‰ to - 3.9‰ VPDB) as well as by nil salinity and low temperature in fluid inclusions of late columnar calcite cement. This study demonstrates that linking fluid flux history and related diagenesis to the tectonic evolution of the basin provides important clues to the timing of oil migration, degradation and reservoir evolution.

  13. Aptian biostratigraphy in South Zagros Basin, southwest Iran

    Institute of Scientific and Technical Information of China (English)

    Massih Afghah; Arash Shaabanpour Haghighi

    2014-01-01

    The Khami group within the petroliferous Zagros Basin of Iran includes the Surmeh, Hith, Fahliyan, Gadvan and Dariyan formations. The Dariyan Formation, previously known as Orbitolina limestone is very signif-icant as a reservoir rock in the Zagros Basin. In this study, the age of the Dariyan Formation is examined based on biostratigraphic and paleontological investigations. 236 m of Dariyan Formation sediments in the sections at Kuh-e Rahmat (north) and Nour-Abad (west) of Iran were selected to study its biostratigraphy. According to the lithostratigraphic investigations, the Dariyan Formation in these sections is subdivided into three: lower, middle and upper, which include thin-bedded to medium-bedded and massive lime-stone. Micropaleontologic study of the Dariyan Formation has led to the recognition of two biozones in the Nour-Abad area and one biozone in the Kuh-e Rahmat stratigraphic column. Diagnostic foraminifera in these sections are as follows: Globigerinel oides algerianus Cushman and Ten Dam, Globigerinelloides fer-reolensis Moullade, Globigerinelloides maridalensis (Bolli), Globigerinelloides paragottisi Verga and Permoli Silva, Hedbergel a aptiana Bartenstein, Hedbergel a excelsa Longoria, Hedbergel a luterbacheri Longoria, Hedbergella occulta Longoria, Hedbergella ruka (Banner et al.), Hedbergella similis Longoria, Hedbergella trocoidea (Gandolfi), Muricohedbergella delrioensis (Carsey), Pseudoplanomalina cheniourensis Sigal, Con-icorbitolina conica d’Archiac, Iraqia sp., Mesorbitolina parva Douglass, Mesorbitolina pervia Douglass, Meso-rbitolina ovalis Gorog and Arnaud-Vanneau, Mesorbitolina subconcava Leymerie, Mesorbitolina texana (Roemer), Mesorbitolina ovalis-pervia Cherchi and Schroeder, Debarina hahounerensis Fourcade et al., Marssonel a trochus (d’Orbigny), Nezzazata sp., Orbitolina sp., Textularia sp.

  14. The Cretaceous Source Rocks in the Zagros Foothills of Iran Les roches mères Crétacé de l'avant-pays du Zagros en Iran : un exemple de bassin intracratonique de grande dimension

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    Bordenave M. L.

    2006-11-01

    Full Text Available Almost all the oil production of Iran is concentrated in a small portion of the Zagros orogenic belt, the 40,000 Sq km Dezful Embayment of the Khuzestan province. The accumulation of oil results from a Cretaceous/Tertiary petroleum complex which includes 6 source rock layers of unequal importance, i. e. the basal part of the Garau Formation (Neocomian, the Gadvan (Barremian, the Kazhdumi (Albian, the Ahmadi (Early Cenomanian, the Gurpi (Senonian and the Pabdeh (Eocene. These layers generated 99% of the onshore Iranian oil reserves, trapped into two main reservoirs, the Asmari (Early Miocene and Bangestan (Cenomanian limestones which contained 330 billions barrels of original oil in place, corresponding to more than 7% of the current global reserves. This paper discusses the distribution of Cretaceous source rocks in the Iranian Foothills and the Iranian side of the Gulf, and the geological, oceanological and climatic factors which favored dysoxic to anoxic conditions and the deposition of organic-rich sediments. The impact of each of these source rocks on oil accumulations is also briefly considered. Among Cretaceous source rocks, two of them, the Neocomian Garau deposited over Lurestan, NE Khuzestan and the northeastern part of the Gulf, and the Albian Kazhdumi, deposited in the central part of the Dezful Embayment, have excellent characteristics with initial organic carbon sometimes higher than 10%, Hydrogen Indices (HI in the 600 g HC/kg C range and maximum thickness in excess of 300 m. Their organic matter is mainly algal with high sulfur content, qualifying them as IIs type. They were deposited in well established depressions included in an overall shallow water intracratonic basin communicating with the Southern Tethys Ocean. These depressions became anoxic as the result of a water stratification caused by the conjunction of high stand waters, humid climate and the existence of a sill separating the depression from the open sea. On the

  15. Growth of the Zagros Fold-Thrust Belt and Foreland Basin, Northern Iraq, Kurdistan

    Science.gov (United States)

    Koshnaw, Renas; Horton, Brian; Stockli, Daniel; Barber, Douglas; Ghalib, Hafidh; Dara, Rebwar

    2016-04-01

    The Zagros orogenic belt in the Middle Eastern segment of the Alpine-Himalayan system is among the youngest seismically active continental collision zones on Earth. However, due to diachronous and incremental collision, the precise ages and kinematics of shortening and deposition remain poorly understood. The Kurdistan region of the Zagros fold-thrust belt and foreland basin contains well-preserved Neogene wedge-top and foredeep deposits that include clastic nonmarine fill of the Upper Fars, Lower Bakhtiari, and Upper Bakhtiari Formations. These deposits record significant information about orogenic growth, fold-thrust dynamics, and advance of the deformation front. Thermochronologic and geochronologic data from thrust sheets and stratigraphic archives combined with local earthquake data provide a unique opportunity to address the linkages between surface and subsurface geologic relationships. This research seeks to constrain the timing and geometry of exhumation and deformation by addressing two key questions: (1) Did the northwestern Zagros fold-thrust belt evolve from initial thin-skinned shortening to later thick-skinned deformation or vice-versa? (2) Did the fold-thrust belt advance steadily under critical/supercritical wedge conditions involving in-sequence thrusting or propagate intermittently under subcritical conditions with out-of-sequence deformation? From north to south, apatite (U-Th)/He ages from the Main Zagros Thrust, the Mountain Front Flexure (MFF), and additional frontal thrusts suggest rapid exhumation by ~10 Ma, ~5 Ma, and ~8 Ma respectively. Field observations and seismic sections indicate progressive tilting and development of growth strata within the Lower Bakhtiari Formation adjacent to the frontal thrusts and within the Upper Bakhtiari Formation near the MFF. In the Kurdistan region of Iraq, a regional balanced cross section constrained by new thermochronometric results, proprietary seismic reflection profiles, and earthquake hypocenters

  16. Coniacian-maastrichtian calcareous nannofossil biostratigraphy and carbon-isotope stratigraphy in the Zagros Basin (Iran)

    DEFF Research Database (Denmark)

    Razmjooei, Mohammad Javad; Thibault, Nicolas; Kani, Anoshiravan;

    2014-01-01

    Calcareous nannofossil biostratigraphy and stable isotope stratigraphy have been investigated in the Shahneshin section of the Gurpi Formation from the Zagros Basin (Iran). The results show that the Gurpi Formation spans the late early Coniacian to late Thanetian. The age-model shows that the...... magnetostratigraphy in the Santonian-early Campanian interval. The δ13C correlation, supported by calcareous nannofossil biostratigraphy, brings insights into: (1) the position of the Coniacian/Santonian, Santonian/Campanian and Campanian/Maastrichtian boundaries with respect to carbon-isotope stratigraphy and...

  17. Non-cylindrical fold growth in the Zagros fold and thrust belt (Kurdistan, NE-Iraq)

    Science.gov (United States)

    Bartl, Nikolaus; Bretis, Bernhard; Grasemann, Bernhard; Lockhart, Duncan

    2010-05-01

    The Zagros mountains extends over 1800 km from Kurdistan in N-Iraq to the Strait of Hormuz in Iran and is one of the world most promising regions for the future hydrocarbon exploration. The Zagros Mountains started to form as a result of the collision between the Eurasian and Arabian Plates, whose convergence began in the Late Cretaceous as part of the Alpine-Himalayan orogenic system. Geodetic and seismological data document that both plates are still converging and that the fold and thrust belt of the Zagros is actively growing. Extensive hydrocarbon exploration mainly focuses on the antiforms of this fold and thrust belt and therefore the growth history of the folds is of great importance. This work investigates by means of structural field work and quantitative geomorphological techniques the progressive fold growth of the Permam, Bana Bawi- and Safeen- Anticlines located in the NE of the city of Erbil in the Kurdistan region of Northern Iraq. This part of the Zagros fold and thrust belt belongs to the so-called Simply Folded Belt, which is dominated by gentle to open folding. Faults or fault related folds have only minor importance. The mechanical anisotropy of the formations consisting of a succession of relatively competent (massive dolomite and limestone) and incompetent (claystone and siltstone) sediments essentially controls the deformation pattern with open to gentle parallel folding of the competent layers and flexural flow folding of the incompetent layers. The characteristic wavelength of the fold trains is around 10 km. Due to faster erosion of the softer rock layers in the folded sequence, the more competent lithologies form sharp ridges with steeply sloping sides along the eroded flanks of the anticlines. Using an ASTER digital elevation model in combination with geological field data we quantified 250 drainage basins along the different limbs of the subcylindrical Permam, Bana Bawi- and Safeen- Anticlines. Geomorphological indices of the drainage

  18. Long-Term Seismicity Behavior of the Zagros Region in Iran

    Science.gov (United States)

    Madahizadeh, Rohollah; Mostafazadeh, Mehrdad; Ansari, Anooshiravan

    2016-08-01

    To achieve a comprehensive attitude about seismicity, it is necessary to consider spatial and magnitude distributions of earthquakes. Earthquake distributions in space and magnitude can be quantified by means of spatial fractal dimension D( s) and Gutenberg-Richter b value. In this paper, b value and D( s) are used to evaluate seismicity of the Zagros zone (Iran) in time interval 1964 to 2012. Seismic catalog of the Zagros zone is extracted from unified seismic catalog of the Iranian Plateau. The b value and D( s) are estimated using frequency-magnitude distribution, Kijko-Sellevoll (Bull Seism Soc Am 79(3):645-654, 1989) and correlation integral methods. Correlations between spatial variations in b value and D( s) along individual profiles across the North Zagros and the Central Zagros indicate different stress release regimes for North and Central parts of the Zagros zone. Evaluation of b value with respect to depth along the profiles indicates larger b values at shallower depths. Temporal variations in b value and D( s) are also obtained from background seismicity to evaluate seismicity behavior of the Zagros zone. Our results indicate high b values and moderate D( s) for seismicity of the North Zagros, while seismicity of the Central Zagros has low b values and high D( s) during time interval 1964-2012. Asperities of the Main Zagros Thrust are also located by investigating ratio D( s)/ b along the Main Zagros Thrust.

  19. Hydrogeochemistry and geothermometry of Changal thermal springs, Zagros region, Iran

    Energy Technology Data Exchange (ETDEWEB)

    Mohammadi, Z.; Bagheri, R.; Jahanshahi, R. [Department of Earth Sciences, Shiraz University, Shiraz (Iran)

    2010-09-15

    This study addresses the hydrogeochemistry of thermal springs that emerge from the Asmari limestone in a gorge at Changal Anticline in the vicinity of the Salman-Farsi dam. The Changal thermal springs vary in temperature between 28 and 40 C. Chemical and isotopic compositions of the thermal waters suggest two distinct hydrogeological systems: a deep, moderate-temperature ({proportional_to}40 C) geothermal system recharged by deeply circulating meteoric waters, and a shallow cold aquifer system related to local groundwater. The source geothermal fluid temperature was calculated using different geothermometers and mineral saturation indexes. Based on chemical and isotopic data, it is hypothesized that: (1) mixing occurs between the ascending geothermal water and shallow cold water; (2) the resulting thermal waters reaching surface are a mixture of 80% local, shallow meteoric water and 20% geothermal water; and (3) the circulation depth of the meteoric water is about 1500 m. The thermal reservoir temperature is estimated to be between 70 and 80 C according to calculations using different geothermometers and computation of saturation indices for different solid phases. (author)

  20. Transakcje kryptowalutą bitcoin - wybrane zagrożenia

    OpenAIRE

    Kądziołka, Kinga

    2015-01-01

    W artykule zwrócono uwagę na wybrane zagrożenia związane z internetowym systemem płatności za pomocą kryptowaluty bitcoin. Poruszone zostały zagadnienia związane z anoniowością w sieci Bitcoin, pozyskiwaniem bitcoinów, prawdopodobieństwem podwójnego wydania środków (ang. double spending), ryzykiem inwestycji w kryptowalutę oraz ryzykiem AML.

  1. Detrital zircon study of the Dezful Embayment in the central Zagros, southern Iran

    Science.gov (United States)

    Hsieh, Hao Cheng; Chung, Sun Lin; Talebian, Morteza; Chen, Ling; Zarrinkoub, Mohammad H.; Lee, Hao Yang

    2016-04-01

    The Dezful Embayment of the Zagros Simply Folded Belt (ZFTB) in southern Iran is a foreland basin that formed as a flexural basin during the Miocene by the Zagros orogeny. This study reports a LA-ICPMS analysis of zircon U-Pb geochronology of 13 sedimentary rock samples from the Dezful Embayment, and five others from the Urumieh-Dokhtar magmatic arc (UDMA) and the Sanandaj-Sirjan zone (SSZ). In the northern and central parts of the Dezful Embayment, samples were collected from four principal sedimentary sequences including, from bottom to top, the Gachsaran Formation, Mishan Formation, Agha Jari Formation and Bakhtyari Formation. Our new zircon ages, together with published geochronological data from the UDMA and SSZ, can be used to better constrain the source provenance and tectonic implication of the Dezful Embayment related to the Arabia-Eurasia collision following the closure of Neo-Tethys. Samples of the UDMA and SSZ are characterized by abundant zircon ages of Eocene to Oligocene (55-25 Ma) and Jurassic (176-144 Ma), respectively. In the Dezful Embayment, detrital zircon age populations show significant variations. The age spectra of the northern Embayment show major peaks at the Precambrian (950-550 Ma), Late Carboniferous (323-299 Ma), Jurassic (176-144 Ma) and Eocene to Oligocene (55-25 Ma), with the last two age peaks suggesting an important source provenance from Eurasia, involving the SSZ and UDMA. By contrast, in the central Embayment, detrital zircons are dominated by Precambrian ages (2500 Ma, 1850 Ma, and 950-550 Ma), with rare Jurassic and Cenozoic ages. This suggests a different sedimentary source that we interpret to be the Arabian continent from the south. Moreover, gradual changes in the detrital zircon age spectra and thus in the source provenances are observed in different parts of the Dezful Embayment. The change in the northern Embayment occurred in the Agha Jari Formation, earlier than that in the central Embayment occurring between the

  2. Spatial evolution of Zagros collision zone in Kurdistan - NW Iran, constraints for Arabia-Eurasia oblique convergence

    Science.gov (United States)

    Sadeghi, S.; Yassaghi, A.

    2015-09-01

    Stratigraphy, detailed structural mapping and crustal scale cross section of the NW Zagros collision zone evolved during convergence of the Arabian and Eurasian plates were conducted to constrain the spatial evolution of the belt oblique convergence since Late Cretaceous. Zagros orogeny in NW Iran consists of the Sanandaj-Sirjan, Gaveh Rud and ophiolite zones as internal, and Bisotoun, Radiolarite and High Zagros zones as external parts. The Main Zagros Thrust is known as major structures of the Zagros suture zone. Two stages of deformation are recognized in the external parts of Zagros. In the early stage, presence of dextrally deformed domains beside the reversely deformed domains in the Radiolarite zone as well as dextral-reverse faults in both Bisotoun and Radiolarite zones demonstrates partitioning of the dextral transpression. In the late stage, southeastward propagation of the Zagros orogeny towards its foreland resulted in synchronous development of orogen-parallel strike-slip and pure thrust faults. It is proposed that the first stage related to the late Cretaceous oblique obduction, and the second stage is resulted from Cenozoic collision. Cenozoic orogen-parallel strike-slip component of Zagros oblique faulting is not confined to the Zagros suture zone (Main Recent) but also occurred in the more external part (Marekhil-Ravansar fault system). Thus, it is proposed that oblique convergence of Arabia-Eurasia plates occurred in Zagros collision zone since the Late Cretaceous.

  3. Foraminiferal biostratigraphy of Early Cretaceous (Hauterivian-Barremian) sediments of the Zagros basin (SW of Iran)

    Science.gov (United States)

    Afghah, Massih; Abtahiyan, Ali-Reza; Saberi, Amir

    2016-09-01

    Parts of Early Cretaceous sediments of the Zagros basin (SW of Iran) is nominated as the Gadvan Formation. To facilitate biostratigraphy study, four stratigraphic sections of this rock unit are selected around Shiraz named as Fahliyan, Kamal abad, Garm abad, and Hossien abad stratigraphic columns. These stratigraphic sections are sandwiched between the Fahliyan and Dariyan formations. Foraminiferal biostratigraphy of these sections have supported two biozones in the three of studied sections and one section is marked by one biozone. Normally established biozones of the studied section are described as Pseudocyclammina lituus-Trocholina assemblage zone (Hauterivian) and Choffatella decipiens- Praechrysalidina infracretacea assemblage zone (Barremian). Two established biozones are recognizable in Fahliyan, Garm abad, and Kamal abad stratigraphic sections as Hauterivian to Barremian age and Hossien abad stratigraphic section is described by one which marks Barremian. Biostratigraphy of the studied stratigraphic sections of the Gadvan reveals different lower biostratigraphic limit whereas; the upper biostratigraphic limit of the Gadvan is synchronous across the entire studied area. Biostratigraphic data of studied stratigraphic sections fully supported the dominant agglutinated foraminifera in Gadvan Formation. Also dasycladacea are recorded in all the studied stratigraphic sections.

  4. Mineralogy, Geochemistry and Stable Isotope Studies of the Dopolan Bauxite Deposit, Zagros Mountain, Iran

    Directory of Open Access Journals (Sweden)

    Somayeh Salamab Ellahi

    2016-02-01

    Full Text Available The Dopolan deposit is a Mediterranean-type bauxite located in the Zagros Fold-Thrust Zone, Iran. This deposit consists of five lithological members including iron-rich, clay-rich, oolitic, pisolitic and organic matter-containing bauxites. The mineralogy of the deposit includes diaspore, boehmite, and kaolinite, nacrite, with minor pyrite, anatase and rutile. Geochemical studies show that light rare earth elements (LREEs are enriched relative to heavy rare earth elements (HREEs in all members, supporting an authigenic origin. Mass changes based on Ti as an immobile element indicate that conventionally-immobile elements (Al, Nb, Ta, Zr, Hf are enriched in situ in the residual units, whereas mobile elements (K, Ca, Si were depleted during bauxitization. This study shows that the Khaneh–Kat argillitic dolomite is the likely parent rock. The δ18O (7.63‰to 9.35‰ and D values (49.91‰to 66.49‰ for kaolinite in the bauxite samples suggest equilibration with meteoric waters which supports a supergene origin. Bauxitization occurred in a warm climate with relatively constant isotopic composition suggesting climate stability during the development of bauxite horizons and remobilization of Al (with formation of secondary boehmite. The δ13C values of calcite (7.3‰ in the bauxite support the idea that the Khaneh–Kat Formation has experienced post-depositional isotope exchange with meteoric waters during the karstification process.

  5. Lateral and depth variations of coda Q in the Zagros region of Iran

    Science.gov (United States)

    Irandoust, Mohsen Ahmadzadeh; Sobouti, Farhad; Rahimi, Habib

    2016-01-01

    We have analyzed more than 2800 local earthquakes recorded by the Iranian National Seismic Network (INSN) and the Iranian Seismological Center (IRSC) to estimate coda wave quality factor, Q c , in the Zagros fold and thrust belt and the Sanandaj-Sirjan metamorphic zone in Iran. We used the single backscattering model to investigate lateral and depth variations of Q c in the study region. In the interior of Zagros, no strong lateral variation in attenuation parameters is observed. In SE Zagros (the Bandar-Abbas region) where transition to the Makran subduction setting begins, the medium shows lower attenuation. The average frequency relations for the SSZ, the Bandar-Abbas region, and the Zagros are Q c = (124 ± 11) f 0.82 ± 0.04, Q c = (109 ± 2) f 0.99 ± 0.01, and Q c = (85 ± 5) f 1.06 ± 0.03, respectively. To investigate the depth variation of Q c , 18 time windows between 5 and 90 s and at two epicentral distance ranges of R < 100 km and 100 < R < 200 km were considered. It was observed that with increasing coda lapse time, Q 0 ( Q c at 1 Hz) and n (frequency dependence factor) show increasing and decreasing trends, respectively. Beneath the SSZ and at depths of about 50 to 80 km, there is a correlation between the reported low velocity medium and the observed sharp change in the trend of Q 0 and n curves. In comparison with results obtained in other regions of the Iranian plateau, the Zagros along with the Alborz Mountains in the north show highest attenuation of coda wave and strongest frequency dependence, an observation that reflects the intense seismicity and active faulting in these mountain ranges. We also observe a stronger depth dependence of attenuation in the Zagros and SSZ compared to central Iran, indicating a thicker lithosphere in the Zagros region than in central Iran.

  6. Spatial evolution of Zagros collision zone in Kurdistan, NW Iran: constraints on Arabia-Eurasia oblique convergence

    Science.gov (United States)

    Sadeghi, Shahriar; Yassaghi, Ali

    2016-04-01

    Stratigraphy, detailed structural mapping and a crustal-scale cross section across the NW Zagros collision zone provide constraints on the spatial evolution of oblique convergence of the Arabian and Eurasian plates since the Late Cretaceous. The Zagros collision zone in NW Iran consists of the internal Sanandaj-Sirjan, Gaveh Rud and Ophiolite zones and the external Bisotoun, Radiolarite and High Zagros zones. The Main Zagros Thrust is the major structure of the Zagros suture zone. Two stages of oblique deformation are recognized in the external part of the NW Zagros in Iran. In the early stage, coexisting dextral strike-slip and reverse dominated domains in the Radiolarite zone developed in response to deformation partitioning due to oblique convergence. Dextral-reverse faults in the Bisotoun zone are also compatible with oblique convergence. In the late stage, deformation partitioning occurred during southeastward propagation of the Zagros orogeny towards its foreland resulting in synchronous development of orogen-parallel strike-slip and thrust faults. It is proposed that the first stage was related to Late Cretaceous oblique obduction, while the second stage resulted from Cenozoic collision. The Cenozoic orogen-parallel strike-slip component of Zagros oblique convergence is not confined to the Zagros suture zone (Main Recent Fault) but also occurred in the external part (Marekhil-Ravansar fault system). Thus, it is proposed that oblique convergence of Arabian and Eurasian plates in Zagros collision zone initiated with oblique obduction in the Late Cretaceous followed by oblique collision in the late Tertiary, consistent with global plate reconstructions.

  7. An integrated approach for determination of pore-type distribution in carbonate-siliciclastic Asmari Reservoir, Cheshmeh-Khosh Oilfield, SW Iran

    Science.gov (United States)

    Gharechelou, Sajjad; Amini, Abdolhossein; Kadkhodaie-Ilkhchi, Ali; Moradi, Babak

    2015-10-01

    This paper presents an integrated pore type study at microscopic (core data), mesoscopic (well logs) and megascopic scales (3D seismic data) in the mixed carbonate-siliciclastic Asmari Reservoir of the Cheshmeh-Khosh Oilfield, SW Iran. Firstly, pore types are determined in a microscopic scale based on petrographic studies of thin sections. Well logs and nuclear magnetic resonance (NMR) log data are employed for pore type determination based on a velocity deviation log (mesoscopic scale). For each pore type subclass, a suite of physical rock properties including average poroperm values, T2 distribution, capillary pressure, pore size distribution and depositional texture are calculated. For this purpose, the NMR log, mercury injection capillary pressure data and core descriptions are interpreted in an integrated approach. Capillary pressure and pore size distribution in each pore type class are determined by mercury injection capillary pressure tests and synthesis of a continuous capillary pressure log from the NMR log (pseudo Pc curves). For dynamic behavior examination of the reservoir, the pore types are analysed in the framework of hydraulic flow units. Finally, 3D post-stacked seismic data are converted to a cube of pore types based on acoustic impedance inversion and seismic attributes. The methodology of this study is accomplished by using core and log data from three key wells and a 3D post-stack seismic data from the studied field. Lastly, a map of pore type distribution is established to provide a clue on the high and low permeable zones of the field. The presented methodology signifies reservoir anatomy on micro to mega scales.

  8. Upliftment Estimation of the Zagros Transverse Fault in Iran Using Geoinformatics Technology

    OpenAIRE

    Biswajeet Pradhan; Saeid Pirasteh; Hojjat Ollah Safari

    2009-01-01

    The Izeh fault zone is a transverse fault zone with dextral strike slip (and some reverse component) in the Zagros Mountains (Iran). It causes some structural deformations. This fault zone is acting as eastern boundary of Dezful Embayment and forms subsidence of the embayment. The fault has been recognized using remote sensing techniques in conjunction with surface and subsurface analyses. The stratigraphic columns have been prepared in 3D form using Geographical Information System (GIS) tool...

  9. Land degradation of Taleghan drainage basin, Iran from saline and alkaline marly formations

    Energy Technology Data Exchange (ETDEWEB)

    Zakikhani, K.; Feiznia, S.; Hosseini, S. H.

    2009-07-01

    In Iran fine-grained, saline, alkaline and erodible Tertiary marly formations are exposed in many geological zones and play important role in the formation of present landforms. They also play important role in degradation of water resources and soils as diffuse sources, they are the main sources of suspension loads of many rivers and are endless sources of sediments for sand dunes. These marly formations are present in Zagros, Central Iran, Alborz and Kopeh Dagh geological Zones and consists of different geological formations such as Gachsaran, Mishan and Razak Formations ( in Zagros), Lower Red and Upper Red Formations ( in Central Iran) and Neogene Red Beds (in Albords and Kopeh Dagh). (Author)

  10. Land degradation of Taleghan drainage basin, Iran from saline and alkaline marly formations

    International Nuclear Information System (INIS)

    In Iran fine-grained, saline, alkaline and erodible Tertiary marly formations are exposed in many geological zones and play important role in the formation of present landforms. They also play important role in degradation of water resources and soils as diffuse sources, they are the main sources of suspension loads of many rivers and are endless sources of sediments for sand dunes. These marly formations are present in Zagros, Central Iran, Alborz and Kopeh Dagh geological Zones and consists of different geological formations such as Gachsaran, Mishan and Razak Formations ( in Zagros), Lower Red and Upper Red Formations ( in Central Iran) and Neogene Red Beds (in Albords and Kopeh Dagh). (Author)

  11. Canopy Density Mapping on Ultracam-D Aerial Imagery in Zagros Woodlands, Iran

    Science.gov (United States)

    Erfanifard, Y.; Khodaee, Z.

    2013-09-01

    Canopy density maps express different characteristics of forest stands, especially in woodlands. Obtaining such maps by field measurements is so expensive and time-consuming. It seems necessary to find suitable techniques to produce these maps to be used in sustainable management of woodland ecosystems. In this research, a robust procedure was suggested to obtain these maps by very high spatial resolution aerial imagery. It was aimed to produce canopy density maps by UltraCam-D aerial imagery, newly taken in Zagros woodlands by Iran National Geographic Organization (NGO), in this study. A 30 ha plot of Persian oak (Quercus persica) coppice trees was selected in Zagros woodlands, Iran. The very high spatial resolution aerial imagery of the plot purchased from NGO, was classified by kNN technique and the tree crowns were extracted precisely. The canopy density was determined in each cell of different meshes with different sizes overlaid on the study area map. The accuracy of the final maps was investigated by the ground truth obtained by complete field measurements. The results showed that the proposed method of obtaining canopy density maps was efficient enough in the study area. The final canopy density map obtained by a mesh with 30 Ar (3000 m2) cell size had 80% overall accuracy and 0.61 KHAT coefficient of agreement which shows a great agreement with the observed samples. This method can also be tested in other case studies to reveal its capability in canopy density map production in woodlands.

  12. Mechanical versus kinematical shortening reconstructions of the Zagros High Folded Zone (Kurdistan region of Iraq)

    Science.gov (United States)

    Frehner, Marcel; Reif, Daniel; Grasemann, Bernhard

    2012-06-01

    This paper compares kinematical and mechanical techniques for the palinspastic reconstruction of folded cross sections in collision orogens. The studied area and the reconstructed NE-SW trending, 55.5 km long cross section is located in the High Folded Zone of the Zagros fold-and-thrust belt in the Kurdistan region of Iraq. The present-day geometry of the cross section has been constructed from field as well as remote sensing data. In a first step, the structures and the stratigraphy are simplified and summarized in eight units trying to identify the main geometric and mechanical parameters. In a second step, the shortening is kinematically estimated using the dip domain method to 11%-15%. Then the same cross section is used in a numerical finite element model to perform dynamical unfolding simulations taking various rheological parameters into account. The main factor allowing for an efficient dynamic unfolding is the presence of interfacial slip conditions between the mechanically strong units. Other factors, such as Newtonian versus power law viscous rheology or the presence of a basement, affect the numerical simulations much less strongly. If interfacial slip is accounted for, fold amplitudes are reduced efficiently during the dynamical unfolding simulations, while welded layer interfaces lead to unrealistic shortening estimates. It is suggested that interfacial slip and decoupling of the deformation along detachment horizons is an important mechanical parameter that controlled the folding processes in the Zagros High Folded Zone.

  13. Fracture patterns in the Zagros fold-and-thrust belt, Kurdistan Region of Iraq

    Science.gov (United States)

    Reif, Daniel; Decker, Kurt; Grasemann, Bernhard; Peresson, Herwig

    2012-11-01

    Fracture data have been collected in the Kurdistan Region of Iraq, which is a poorly accessible and unexplored area of the Zagros. Pre to early folding NE-SW striking extensional fractures and NW-SE striking contractive elements represent the older set affecting the exposed multilayer of the area. These latter structures are early syn-folding and followed by folding-related mesostructural assemblages, which include elements striking parallel to the axial trend of major folds (longitudinal fractures). Bedding perpendicular joints and veins, and extensional faults belonging to this second fracture set are located in the outer arc of exposed anticlines, whilst longitudinal reverse faults locate in the inner arcs. Consistently, these elements are associated with syn-folding tangential longitudinal strain. The younger two sets are related to E-W extension and NNE-SSW to N-S shortening, frequently displaying reactivation of the older sets. The last shortening event, which is described along the entire Zagros Belt, probably relates with the onset of N-S compression induced by the northward movement of the Arabian plate relative to the Eurasian Plate. In comparison between the inferred palaeostrain directions and the kinematics of recent GPS measurements, we conclude that the N-S compression and the partitioning into NW-SE trending folds and NW to N trending strike-slip faults likely remained unchanged throughout the Neogene tectonic history of the investigated area.

  14. The genetics of an early Neolithic pastoralist from the Zagros, Iran

    KAUST Repository

    Gallego-Llorente, M.

    2016-08-09

    The agricultural transition profoundly changed human societies. We sequenced and analysed the first genome (1.39x) of an early Neolithic woman from Ganj Dareh, in the Zagros Mountains of Iran, a site with early evidence for an economy based on goat herding, ca. 10,000 BP. We show that Western Iran was inhabited by a population genetically most similar to hunter-gatherers from the Caucasus, but distinct from the Neolithic Anatolian people who later brought food production into Europe. The inhabitants of Ganj Dareh made little direct genetic contribution to modern European populations, suggesting those of the Central Zagros were somewhat isolated from other populations of the Fertile Crescent. Runs of homozygosity are of a similar length to those from Neolithic farmers, and shorter than those of Caucasus and Western Hunter-Gatherers, suggesting that the inhabitants of Ganj Dareh did not undergo the large population bottleneck suffered by their northern neighbours. While some degree of cultural diffusion between Anatolia, Western Iran and other neighbouring regions is possible, the genetic dissimilarity between early Anatolian farmers and the inhabitants of Ganj Dareh supports a model in which Neolithic societies in these areas were distinct.

  15. Structural style across the Bandar Abbas syntaxis, SE Zagros: facts and factors of a subduction to collision transition

    Science.gov (United States)

    Molinaro, M.; Guezou, J. C.; Aubourg, C.; Leturmy, P.; Eshraghi, S. A.

    2003-04-01

    Marking the transition between the Zagros collisional belt and the Makran subduction-related prism, the Bandar Abbas syntaxis constitutes an active and major structural and geodynamic boundary within the Alpine - Himalayan mountain belt. Within the foreland part of the Zagros (the Zagros Simple Fold Belt, ZSFB) this transition is accompanied by a sudden swing in structural directions and a change in structural style. We present kinematically constrained cross-sections based upon recent fieldwork, analysis of high resolution satellite images and existing geological maps. This work suggests the following considerations concerning the mode with which convergence is being absorbed within the Arabian passive margin: (1) at least three potential decollement levels are active in the region, allowing to separate sets of independent structural packets; (2) several structures are connected to basement faulting, a suggestion which is confirmed by a strong seismicity record for the region; (3) along-strike deflections and lateral continuity of structures could be affected by uneven distribution of the basal Hormuz evaporitic series; (4) the so called Main Zagros Thrust, traditionally regarded as being the suture between the Arabian and Eurasian plates, in this area appears to be a shallow north dipping passive roof thrust; ongoing underthrusting of the Arabian plate has caused imbrication within the foreland sedimentary rocks and transported thin sheets of allochtonous Eocene flysch and ophiolites over the ZSFB.

  16. Zagros blueschists: Episodic underplating and long-lived cooling of a subduction zone

    Science.gov (United States)

    Angiboust, Samuel; Agard, Philippe; Glodny, Johannes; Omrani, Jafar; Oncken, Onno

    2016-06-01

    Pressure-temperature-time (P- T- t) trajectories of high-pressure rocks provide important constraints to understand the tectonic evolution of convergent margins. New field observations and P- T- t constraints for the evolution of the only known blueschist-facies exposure along the Zagros suture zone in Southern Iran are reported here. These blueschists, now exposed in tectonic windows under the Sanandaj-Sirjan zone (upper plate), constitute accreted fragments of the Tethyan domain during N-directed Cretaceous subduction. Three units were identified in the field: from top to bottom, the Ashin unit (mafic and felsic gneisses), the Seghin complex (mafic tuffs and ultramafics) and the Siah Kuh massif (coherent volcanic edifice). Microstructural observations, P- T estimates and Rb-Sr deformation ages indicate that the Ashin unit possibly underwent burial down to 30-35 km and 550 °C along a relatively warm P- T gradient (c. 17°/km) and was ultimately deformed between 85 and 100 Ma. The Seghin complex exhibits remarkably well-preserved HP-LT assemblages comprising lawsonite, glaucophane, aragonite, omphacite and garnet. P- T- t reconstruction indicates that this slice was subducted down to c. 50 km at temperatures of c. 500 °C along a very cold subduction gradient (c. 7°/km). Deformation in the Seghin complex stopped at around 65 Ma, close to peak metamorphic conditions. Field relationships and estimates of the P- T trajectory followed by the Siah Kuh volcanic edifice indicate that this massif was lately subducted down to 15 km depth along the same very cold gradient. This slice-stack represents a well-preserved field example (i) highlighting the existence of transient underplating processes juxtaposing pluri-kilometric tectonic slices along the subduction channel and (ii) imaging the discontinuous down-stepping of the active main subduction thrust with ongoing accretion. The Zagros blueschists also record an apparent cooling of the Zagros subduction zone between 90

  17. Short-term abandonment of human disturbances in Zagros Oak forest ecosystems: Effects on secondary succession of soil seed bank and aboveground vegetation

    OpenAIRE

    MEHDI HEYDARI; DAVID POTHIER; MARZBAN FARAMARZI; JAVAD MERZAEI

    2014-01-01

    Heydari M, Pothier D, Faramarzi M, Merzaei J. 2014. Short-term abandonment of human disturbances in Zagros Oak forest ecosystems: Effects on secondary succession of soil seed bank and aboveground vegetation. Biodiversitas 15: 147-161. Zagros Oak forests in the west of Iran have been degraded by anthropogenic activities during many years and to fight against this degradation, several management strategies have been implemented. The principal objectives this study were to identify the character...

  18. Exsolution Lamellae in Orthopyroxene of Lherzolite from the Pauza Ultramafic Rocks, Ne Iraq: Evidence of Deep Mantle Signature in the Zagros Suture Zone

    OpenAIRE

    Yousif Osman Mohammad; Nabaz Rashid Hama

    2013-01-01

    The Pauza ultramafic body is part of Upper Cretaceous Ophiolitic massifs of the Zagros Suture Zone, NE Iraq. The present study reveals evidence of Ultra-high pressure (UHP), and deep mantle signature of these peridotites in the Zagros Suture Zone throughout the observation of backscattered images and micro analyses which have been performed on orthopyroxen crystals in lherzolite of Pauza ultramafic rocks.Theorthopyroxen shows abundant exsolution lamellae of coarse unevenly distributed clinopy...

  19. Role of Neogene Exhumation and Sedimentation on Critical-Wedge Kinematics in the Zagros Orogenic Belt, Northeastern Iraq, Kurdistan

    Science.gov (United States)

    Koshnaw, R. I.; Horton, B. K.; Stockli, D. F.; Barber, D. E.; Tamar-Agha, M. Y.; Kendall, J. J.

    2014-12-01

    The Zagros orogenic belt and foreland basin formed during the Cenozoic Arabia-Eurasia collision, but the precise histories of shortening and sediment accumulation remain ambiguous, especially at the NW extent of the fold-thrust belt in Iraqi Kurdistan. This region is characterized by well-preserved successions of Cenozoic clastic foreland-basin fill and deformed Paleozoic-Mesozoic hinterland bedrock. The study area provides an excellent opportunity to investigate the linkage between orogenic wedge behavior and surface processes of erosion and deposition. The aim of this research is to test whether the Zagros orogenic wedge advanced steadily under critical to supercritical wedge conditions involving in-sequence thrusting with minimal erosion or propagated intermittently under subcritical condition involving out-of-sequence deformation with intense erosion. These endmember modes of mountain building can be assessed by integrating geo/thermochronologic and basin analyses techniques, including apatite (U-Th)/He thermochronology, detrital zircon U-Pb geochronology, stratigraphic synthesis, and seismic interpretations. Preliminary apatite (U-Th)/He data indicate activation of the Main Zagros Fault (MZF) at ~10 Ma with frontal thrusts initiating at ~8 Ma. However, thermochronometric results from the intervening Mountain Front Flexure (MFF), located between the MZF and the frontal thrusts, suggest rapid exhumation at ~6 Ma. These results suggest that the MFF, represented by the thrust-cored Qaradagh anticline, represents a major episode of out-of-sequence deformation. Detrital zircon U-Pb analyses from the Neogene foreland-basin deposits show continuous sediment derivation from sources to the NNE in Iraq and western Iran, suggesting that out-of-sequence thrusting did not significantly alter sedimentary provenance. Rather, intense hinterland erosion and recycling of older foreland-basin fill dominated sediment delivery to the basin. The irregular distribution of

  20. Long-Period Ground Motion in the Arabian Gulf from Earthquakes in the Zagros Mountains Thrust Belt

    Science.gov (United States)

    Pitarka, Arben; Al-Amri, Abdullah; Pasyanos, Michael E.; Rodgers, Arthur J.; Mellors, Robert J.

    2015-10-01

    The Arabian Gulf is adjacent to the Zagros Mountains, one of the most seismically active regions in the world. We observe that broadband seismic records of Zagros earthquakes recorded on the Arabian side of the Gulf display long-duration surface waves. While shorter periods (10 km) of the Gulf basin, the long-period energy is enhanced and transmitted efficiently. Consequently, large earthquakes in the Zagros could result in amplified ground motions at long periods (2-10 s) relative to average behavior. Such ground motions are of concern for large engineered structures, such as tall buildings and long bridges with resonant periods in the same period range. Here we present results of investigations of the characteristics of ground motions recorded on the western shore of the Gulf from selected earthquakes in the Zagros Mountains region. Exceptionally, long-duration seismic waves, as compared with standard models, are shown to occur with periods of 2-10 s. This may be due to waveguide effects in the deep sedimentary basin structure of the Arabian Platform. In addition to analyzing recorded ground motion we performed 3D wave propagation simulations using a finite difference method and experimental velocity models of the Gulf, with different shallow sedimentary layers structures. The simulation results confirm our hypothesis that long-period waves with extremely long duration and relatively large amplitudes are caused by the geometry of the basin sedimentary layers and, to some extent, by shallow earthquake depths. Combined effects of basin edge geometry with sharp velocity contrasts and shallow sources (<10 km) on the eastern side of the Arabian Gulf can cause large long-period ground motion on the western side of the Gulf. In contrast, the short-period content of ground motion (<2 s) at long distances is relatively weak. This is mainly due to wave propagation scattering and attenuation in the shallow sedimentary layers of the Gulf basin.

  1. Herbaceous species diversity in relation to fire severity in Zagros oak forests, Iran

    Institute of Scientific and Technical Information of China (English)

    Morteza Pourreza; Seyed Mohsen Hosseini; Ali Akbar Safari Sinegani; Mohammad Matinizadeh; Seyed Jalil Alavai

    2014-01-01

    Zagros forests are mainly covered byQuercus brantii L. coppices and oak sprout clumps occupy the forest area like patches. We investigated post-fire herbaceous diversity in the first growing season after fire. For this purpose neighboring burned and unburned areas were selected with the same plant species and ecological conditions. The data were collected from areas subjected to different fire severities. Overall 6 treatments were considered with respect to fire severity and the mi-crosites of inside and outside of oak sprout clumps including: unburned inside and outside of sprout clumps (Ni and No), inside of sprout clumps that burned with high fire severity (H), inside of sprout clumps that burned with moderate fire severity (M), outside of sprout clumps that burned with low fire severity (OH and OM). Different herbaceous com-position was observed in the unburned inside and outside of oak sprout clumps. The species diversity and richness were increased in treatments burned with low and moderate fire severity. However, in treatment burned with high fire severity (H), herbaceous cover was reduced, even-ness was increased, and richness and diversity were not significantly changed. We concluded that besides the microsites conditions in forest, fire severity is an inseparable part of the ecological effect of fire on her-baceous composition.

  2. The genetics of an early Neolithic pastoralist from the Zagros, Iran

    KAUST Repository

    Gallego Llorente, Marcos

    2016-06-18

    The agricultural transition profoundly changed human societies. We sequenced and analysed the first genome (1.39x) of an early Neolithic woman from Ganj Dareh, in the Zagros Mountains of Iran, a site with early evidence for an economy based on goat herding,ca. 10,000 BP. We show that Western Iran was inhabited by a population genetically most similar to hunter-gatherers from the Caucasus, but distinct from the Neolithic Anatolian people who later brought food production into Europe. The inhabitants of Ganj Dareh made little direct genetic contribution to modern European populations, suggesting they were somewhat isolated from other populations in the region. Runs of homozygosity are of a similar length to those from Neolithic Anatolians, and shorter than those of Caucasus and Western Hunter-Gatherers, suggesting that the inhabitants of Ganj Dareh did not undergo the large population bottleneck suffered by their northern neighbours. While some degree of cultural diffusion between Anatolia, Western Iran and other neighbouring regions is possible, the genetic dissimilarity of early Anatolian farmers and the inhabitants of Ganj Dareh supports a model in which Neolithic societies in these areas were distinct.

  3. Effects of Heterogeniety on Spatial Pattern Analysis of Wild Pistachio Trees in Zagros Woodlands, Iran

    Science.gov (United States)

    Erfanifard, Y.; Rezayan, F.

    2014-10-01

    Vegetation heterogeneity biases second-order summary statistics, e.g., Ripley's K-function, applied for spatial pattern analysis in ecology. Second-order investigation based on Ripley's K-function and related statistics (i.e., L- and pair correlation function g) is widely used in ecology to develop hypothesis on underlying processes by characterizing spatial patterns of vegetation. The aim of this study was to demonstrate effects of underlying heterogeneity of wild pistachio (Pistacia atlantica Desf.) trees on the second-order summary statistics of point pattern analysis in a part of Zagros woodlands, Iran. The spatial distribution of 431 wild pistachio trees was accurately mapped in a 40 ha stand in the Wild Pistachio & Almond Research Site, Fars province, Iran. Three commonly used second-order summary statistics (i.e., K-, L-, and g-functions) were applied to analyse their spatial pattern. The two-sample Kolmogorov-Smirnov goodness-of-fit test showed that the observed pattern significantly followed an inhomogeneous Poisson process null model in the study region. The results also showed that heterogeneous pattern of wild pistachio trees biased the homogeneous form of K-, L-, and g-functions, demonstrating a stronger aggregation of the trees at the scales of 0-50 m than actually existed and an aggregation at scales of 150-200 m, while regularly distributed. Consequently, we showed that heterogeneity of point patterns may bias the results of homogeneous second-order summary statistics and we also suggested applying inhomogeneous summary statistics with related null models for spatial pattern analysis of heterogeneous vegetations.

  4. EFFECTS OF HETEROGENIETY ON SPATIAL PATTERN ANALYSIS OF WILD PISTACHIO TREES IN ZAGROS WOODLANDS, IRAN

    Directory of Open Access Journals (Sweden)

    Y. Erfanifard

    2014-10-01

    Full Text Available Vegetation heterogeneity biases second-order summary statistics, e.g., Ripley's K-function, applied for spatial pattern analysis in ecology. Second-order investigation based on Ripley's K-function and related statistics (i.e., L- and pair correlation function g is widely used in ecology to develop hypothesis on underlying processes by characterizing spatial patterns of vegetation. The aim of this study was to demonstrate effects of underlying heterogeneity of wild pistachio (Pistacia atlantica Desf. trees on the second-order summary statistics of point pattern analysis in a part of Zagros woodlands, Iran. The spatial distribution of 431 wild pistachio trees was accurately mapped in a 40 ha stand in the Wild Pistachio & Almond Research Site, Fars province, Iran. Three commonly used second-order summary statistics (i.e., K-, L-, and g-functions were applied to analyse their spatial pattern. The two-sample Kolmogorov-Smirnov goodness-of-fit test showed that the observed pattern significantly followed an inhomogeneous Poisson process null model in the study region. The results also showed that heterogeneous pattern of wild pistachio trees biased the homogeneous form of K-, L-, and g-functions, demonstrating a stronger aggregation of the trees at the scales of 0–50 m than actually existed and an aggregation at scales of 150–200 m, while regularly distributed. Consequently, we showed that heterogeneity of point patterns may bias the results of homogeneous second-order summary statistics and we also suggested applying inhomogeneous summary statistics with related null models for spatial pattern analysis of heterogeneous vegetations.

  5. SPATIAL DEFORESTATION MODELILNG USING CELLULAR AUTOMATA (CASE STUDY: CENTRAL ZAGROS FORESTS

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    M. Naghdizadegan

    2013-09-01

    Full Text Available Forests have been highly exploited in recent decades in Iran and deforestation is going to be the major environmental concern due to its role in destruction of natural ecosystem and soil cover. Therefore, finding the effective parameters in deforestation and simulation of this process can help the management and preservation of forests. It helps predicting areas of deforestation in near future which is a useful tool for making socioeconomic disciplines in order to prevent deforestation in the area. Recently, GIS technologies are widely employed to support public policies in order to preserve ecosystems from undesirable human activities. The aim of this study is modelling the distribution of forest destruction in part of Central Zagros Mountains and predicting its process in future. In this paper we developed a Cellular Automata (CA model for deforestation process due to its high performance in spatial modelling, land cover change prediction and its compatibility with GIS. This model is going to determine areas with deforestation risk in the future. Land cover maps were explored using high spatial resolution satellite imageries and the forest land cover was extracted. In order to investigate the deforestation modelling, major elements of forest destruction relating to human activity and also physiographic parameters was explored and the suitability map was produced. Then the suitability map in combination with neighbourhood parameter was used to develop the CA model. Moreover, neighbourhood, suitability and stochastic disturbance term were calibrated in order to improve the simulation results. Regarding this, several neighbourhood configurations and different temporal intervals were tested. The accuracy of model was evaluated using satellite image. The results showed that the developed CA model in this research has proper performance in simulation of deforestation process. This model also predicted the areas with high potential for future

  6. Along-strike structural variation and thermokinematic development of the Cenozoic Bitlis-Zagros fold-thrust belt, Turkey and Iraqi Kurdistan

    Science.gov (United States)

    Barber, Douglas E.; Stockli, Daniel F.; Koshnaw, Renas I.; Tamar-Agha, Mazin Y.; Yilmaz, Ismail O.

    2016-04-01

    The Bitlis-Zagros orogen in northern Iraq is a principal element of the Arabia-Eurasia continent collision and is characterized by the lateral intersection of two structural domains: the NW-SE trending Zagros proper system of Iran and the E-W trending Bitlis fold-thrust belt of Turkey and Syria. While these components in northern Iraq share a similar stratigraphic framework, they exhibit along-strike variations in the width and style of tectonic zones, fold morphology and trends, and structural inheritance. However, the distinctions of the Bitlis and Zagros segments remains poorly understood in terms of timing and deformation kinematics as well as first-order controls on fold-thrust development. Structural and stratigraphic study and seismic data combined with low-T thermochronometry provide the basis for reconstructions of the Bitlis-Zagros fold-thrust belt in southeastern Turkey and northern Iraq to elucidate the kinematic and temporal relationship of these two systems. Balanced cross-sections were constructed and incrementally restored to quantify the deformational evolution and use as input for thermokinematic models (FETKIN) to generate thermochronometric ages along the topographic surface of each cross-section line. The forward modeled thermochronometric ages from were then compared to new and previously published apatite and zircon (U-Th)/He and fission-track ages from southeastern Turkey and northern Iraq to test the validity of the timing, rate, and fault-motion geometry associated with each reconstruction. The results of these balanced theromokinematic restorations integrated with constraints from syn-tectonic sedimentation suggest that the Zagros belt between Erbil and Suleimaniyah was affected by an initial phase of Late Cretaceous exhumation related to the Proto-Zagros collision. During the main Zagros phase, deformation advanced rapidly and in-sequence from the Main Zagros Fault to the thin-skinned frontal thrusts (Kirkuk, Shakal, Qamar) from middle

  7. Qualitative and financial evaluation of public and private forest nurseries; Case study of southern Zagros forests, Iran

    Directory of Open Access Journals (Sweden)

    MARYAM FAZLOLLAHI MOHAMMADI

    2014-11-01

    Full Text Available Mohammadi MF, Vaezin SMH, Etemad V, Sepahvand A, Shirvani A, Azam S. 2014. Qualitative and financial evaluation of public and private forest nurseries; Case study of southern Zagros forests, Iran. Nusantara Bioscience 6: 152-158. This study has examined the efficiency of two nurseries, private and public divisions, based on qualitative and financial evaluation in the Southern Zagros forests of Iran. To achieve this purpose, we selected two species including pistachio (Pistacia atlantica and poplar (Popolus nigra in one year period. Results of qualitative evaluation showed that all produced seedlings by private nursery significantly had better features than the public one at the significant level of 0.05. Also, the results of financial evaluation showed that cost price of each poplar seedling at private nursery (0.734 $ was 19.6 times less than public one (14.4 $. The interest rate for pistachio seedling in private sector ranges from 1.9 to 2.2 $, while it ranges from 1.5 to 1.9 $ for poplar seedling. Such researches may help to improve management as well as financial and qualitative efficiency, especially in public nurseries. Future researches will be required to document other aspects of private management on nurseries in seedling products.

  8. Naghan (Chahar Mahal Bakhtiari-High Zagros, Iran Earthquake of 6 april 1977. A preliminary field report and a seismotectonic discussion

    Directory of Open Access Journals (Sweden)

    M. BERBERIAN

    1978-06-01

    Full Text Available

    The Naghan earthquake of magnitude 6 (Ms occurred on 6 April
    1977 in the mountanious area of Chahar Mahal Bakhtiari in the High
    Zagros, south of Shahr-e-Kord. It killed 348 people, injured about 200,
    and caused destruction over an area of 150 Km2. The shock damaged
    beyond repair 2,100 houses and killed 0.7°/o of livestock in the area;
    eight schools collapsed and 37 were damaged. The maximum intensity
    ot' the main shock did not exceed VIII (MM.
    The earthquake was associated neither with any fresh surface faulting,
    nor with reactivation of the existing faults and salt domes at
    surface. Heavy rain fell before and during the earthquake and the
    destruction was more extensive where the saturated clay content of the
    alluvium was higher; it was also more extensive in water-logged areas
    or the areas with a shallower water table. Landslides occurred on steep
    slopes and destroyed or damaged some villages built on slopes. Several
    aftershocks caused additional damage to the already destroyed or
    damaged villages.
    The Naghan earthquake was another instance of the « subsedimentary
    Zagros-Type Earthquake » in the High Zagros part of the Zagros Active

    Folded Belt, indicating that the re-adjustment of the unexposed metamorphosed
    Precambrian Basement at depth caused no tectonic deformation
    (surface faulting at the top of the sedimentary cover. This was
    due to the presence of the Upper Precambrian Hormoz layers (Salt
    deposits acting as a slippage zone along the decollement surface of the
    Zagros at depth.

  9. Quantification of fold growth of frontal antiforms in the Zagros fold and thrust belt (Kurdistan, NE Iraq)

    Science.gov (United States)

    Bretis, Bernhard; Bartl, Nikolaus; Graseman, Bernhard; Lockhart, Duncan

    2010-05-01

    The Zagros fold and thrust belt is a seismically active orogen, where actual kinematic models based on GPS networks suggest a north-south shortening between Arabian and Eurasian in the order of 1.5-2.5 cm/yr. Most of this deformation is partitioned in south-southwest oriented folding and thrusting with northwest-southeast to north-south trending dextral strike slip faults. The Zagros fold and thrust belt is of great economic interest because it has been estimated that this area contains about 15% of the global recoverable hydrocarbons. Whereas the SE parts of the Zagros have been investigated by detailed geological studies, the NW extent being part of the Republic of Iraq have experienced considerably less attention. In this study we combine field work and remote sensing techniques in order to investigate the interaction of erosion and fold growth in the area NE of Erbil (Kurdistan, Iraq). In particular we focus on the interaction of the transient development of drainage patterns along growing antiforms, which directly reflects the kinematics of progressive fold growth. Detailed geomorphological studies of the Bana Bawi-, Permam- and Safeen fold trains show that these anticlines have not developed from subcylindrical embryonic folds but they have merged from different fold segments that joined laterally during fold amplification. This fold segments with length between 5 and 25 km have been detected by mapping ancient and modern river courses that initially cut the nose of growing folds and eventually got defeated leaving behind a wind gap. Fold segments, propagating in different directions force rivers to join resulting in steep gorges, which dissect the merging fold noses. Along rapidly lateral growing folds (e.g. at the SE end of the Bana Bawi Anticline) we observed "curved wind gaps", a new type of abandoned river course, where form of the wind gap mimics a formed nose of a growing antiform. The inherited curved segments of uplifted curved river courses strongly

  10. Structural modeling of the Zagros fold-and-thrust belt (Iraq) combining field work and remote sensing techniques

    Science.gov (United States)

    Reif, D.; Grasemann, B.; Faber, R.; Lockhart, D.

    2009-04-01

    The Zagros fold-and-thrust belt is known for its spectacular fold trains, which have formed in detached Phanerozoic sedimentary cover rocks above a shortened crystalline Precambrian basement. Orogeny evolved through the Late Cretaceous to Miocene collision between the Arabian and Eurasian plate, during which the Neotethys oceanic basin was closed. Still active deformation shortening in the order of 2-2.5 cm/yr is partitioned in S-SW directed folding and thrusting of the Zagros fold-and-thrust belt and NW-SE to N-S trending dextral strike slip faults. The sub-cylindrical doubly-plunging fold trains with wavelengths of 5 - 10 km host more than half of the world's hydrocarbon reserves in mostly anticlinal traps. In this work we investigate the three dimensional structure of the Zagros fold-and-thrust belt in the Kurdistan region of Iraq. The mapped region is situated NE from the city of Erbil and comprises mainly Cretaceous to Cenozoic folded sediments consisting of mainly limestones, dolomites, sandstones, siltstones, claystones and conglomerates. Although the overall security situation in Kurdistan is much better than in the rest of Iraq, structural field mapping was restricted to sections along the main roads perpendicular to the strike of the fold trains, mainly because of the contamination of the area with landmines and unexploded ordnance, a problem that dates back to the end of World War Two. Landmines were also used by the central government in the 1960s and 1970s in order to subdue Kurdish groups. During the 1980-1988 Iran-Iraq War, the north was mined again. In order to extend the structural measurements statistically over the investigated area resulting in a three-dimensional model of the fold trains, we used the Fault Trace module of the WinGeol software (www.terramath.com). This package allows the interactive mapping and visualization of the spatial orientations (i.e. dip and strike) of geological finite planar structures (e.g. faults, lithological

  11. Refinement of stratigraphy according to the first finds of planktonic species of Orbulina and Praeorbulina from the Guri Limestone of the Mishan Formation in northwest of Bandar Abbas, South Iran

    Science.gov (United States)

    Daneshian, J.; Moallemi, S. A.; Derakhshani, M.

    2016-05-01

    The Zagros Basin is one of the most universal oil and gas basins that is located in the west to south of Iran and in north of the Arabian Plate. The Guri Member at the bottom of the Mishan Formation, in some areas such as Bandar Abbas hinterland, contains a significant amount of gas. The Bandar Abbas hinterland is located in the southeast of Zagros. The Guri Limestone is the youngest hydrocarbon reservoirs of the Zagros Sedimentary Basin. In this study, a total of 178 samples from the Guri Limestone in the Handun section are investigated for foraminiferal biostratigraphy. The study of foraminifers led to a recognition of 43 genera and 57 species of benthic and planktonic foraminifera. For the first time, planktonic foraminiferal species including Praeorbulina glomerosa, Praeorbulina transitoria, Orbulina suturalis, and Orbulina universa are reported, and based on the identified benthic and planktonic foraminifera taxa, the age of the Guri Member at Handun section is estimated as late Burdigalian to Langhian.

  12. Transient, synobduction exhumation of Zagros blueschists inferred from P-T, deformation, time, and kinematic constraints: Implications for Neotethyan wedge dynamics

    Science.gov (United States)

    Agard, P.; Monié, P.; Gerber, W.; Omrani, J.; Molinaro, M.; Meyer, B.; Labrousse, L.; Vrielynck, B.; Jolivet, L.; Yamato, P.

    2006-11-01

    We present the first P-T, deformation time, and kinematic constraints on the only known blueschist facies rocks (BS) present in the Zagros (Hajiabad area). The BS were underplated below the Sanandaj-Sirjan zone and crop out as kilometer-scale bodies within extensive colored melange units marking discontinuously the Neotethyan suture zone. P-T estimates point to high-pressure/low-temperature (HP-LT) conditions around 11 kbar and 520-530°C for the majority of BS, along a ˜15°C km-1 gradient. Some exotic blocks in matrix serpentinite reached 17-18 kbar at ˜500°C. In situ laser probe 40Ar-39Ar radiometric age constraints on phengite cluster between 85 and 95 Ma and suggest that (1) synconvergence exhumation of Zagros BS from 35-50 km to depths <15-20 km was accomplished before 80 Ma, (2) BS exhumation corresponded to a transient process with respect to the long-lived subduction beneath Iran (˜150-35 Ma), and (3) age constraints for Zagros BS are 5-10 Myr older than for the nearby Oman HP-LT rocks and broadly coincide with obduction processes in the region (circa 95-70 Ma). We propose that the mechanical coupling across the Neotethyan subduction zone (NSZ) beneath Iran was modified by the large-scale plate rearrangement accompanying obduction, allowing for a short-lived exhumation of Zagros BS. Exhumation ceased at the end of obduction, when subduction of the Arabian continental margin stopped. Kinematic calculations suggest that convergence velocities across the NSZ likely doubled (to ˜5-6 cm yr-1) during the period 118-85 Ma, so that BS exhumation may have been promoted by a combination of obduction movements and increased convergence velocities.

  13. Sinkholes, collapse structures and large landslides in an active salt dome submerged by a reservoir: The unique case of the Ambal ridge in the Karun River, Zagros Mountains, Iran

    Science.gov (United States)

    Gutiérrez, Francisco; Lizaga, Iván

    2016-02-01

    Ambal ridge, covering 4 km2, is a salt pillow of Gachsaran Formation with significant salt exposures in direct contact with the Karun River, Zagros Mountains. The highly cavernous salt dome is currently being flooded by the Gotvand Reservoir, second largest in Iran. Geomorphic evidence, including the sharp deflection of the Karun River and defeated streams indicate that Ambal is an active halokinetic structure, probably driven by erosional unloading. Around 30% of the salt dome is affected by large landslides up to ca. 50 × 106 m3 in volume. Slope oversteepening related to fluvial erosion and halokinetic rise seems to be the main controlling factor. A total of 693 sinkholes have been inventoried (170 sinkholes/km2), for which a scaling relationship has been produced. The depressions occur preferentially along a belt with a high degree of clustering. This spatial distribution is controlled by the proximity to the river, slope gradient and halite content in the bedrock. A large compound depression whose bottom lies below the normal maximum level of the reservoir will likely be flooded by water table rise forming a lake. The impoundment of the reservoir has induced peculiar collapse structures 220-280 m across, expressed by systems of arcuate fissures and scarps. Rapid subsurface salt dissolution is expected to generate and reactivate a large number of sinkholes and may reactivate landslides with a significant vertical component due to lack of basal support.

  14. Balancing cross-sections combining field work and remote sensing data using LithoTect software in the Zagros fold-and-thrust belt, N Iraq.

    Science.gov (United States)

    Reif, Daniel; Grasemann, Bernhard; Lockhart, Duncan

    2010-05-01

    The Zagros fold-and-thrust belt has formed in detached Phanerozoic sedimentary cover rocks above a shortened crystalline Precambrian basement and evolved through the Late Cretaceous to Miocene collision between the Arabian and Eurasian plate, during which the Neotethys oceanic basin was closed. Deformation is partitioned in SW directed folding and thrusting of the sediments and NW-SE to N-S trending dextral strike slip faults. The sub-cylindrical doubly-plunging fold trains with wavelengths of 5 - 10 km host more than half of the world's hydrocarbon reserves in mostly anticlinal traps. Generally the Zagros is divided into three NW-SE striking tectonic units: the Zagros Imbricate Zone, the Zagros Simply Folded Belt and the Zagros Foredeep. This work presents a balanced cross-section through the Simply Folded Belt, NE of the city of Erbil (Kurdistan, Iraq). The regional stratigraphy comprises mainly Cretaceous to Cenozoic folded sediments consisting of massive, carbonate rocks (limestones, dolomites), reacting as competent layers during folding compared to the incompetent behavior of interlayered siltstones, claystones and marls. Although the overall security situation in Kurdistan is much better than in the rest of Iraq, structural field mapping was restricted to asphalt streets, mainly because of the contamination of the area with landmines and unexploded ordnance. In order to extend the structural measurements statistically over the investigated area, we used a newly developed software tool (www.terramath.com) for interactive structural mapping of spatial orientations (i.e. dip direction and dip angles) of the sedimentary beddings from digital elevation models. Structural field data and computed measurements where integrated and projected in NE-SW striking balanced cross-sections perpendicular to the regional trend of the fold axes. We used the software LithoTect (www.geologicsystems.com) for the restoration of the cross-sections. Depending on the interpretation

  15. Detrital zircon provenance analysis in the Zagros Orogen, SW Iran: implications for the amalgamation history of the Neo-Tethys

    Science.gov (United States)

    Zhang, Zhiyong; Xiao, Wenjiao; Majidifard, Mahmoud Reza; Zhu, Rixiang; Wan, Bo; Ao, Songjian; Chen, Ling; Rezaeian, Mahnaz; Esmaeili, Rasoul

    2016-03-01

    The Zagros Orogen developed as a result of Arabia-Eurasia collision. New in situ detrital zircon U-Pb and Hf isotopic analyses from a Cenozoic sedimentary sequence in SW Iran are used to unravel the amalgamation history of Neo-Tethys. Data indicate that: (1) Paleocene and Eocene strata (58 and 45 Ma, respectively) were sourced from obducted ophiolite and Triassic volcanics, (2) Lower Miocene (~18 Ma) strata indicate mixed provenance from obducted ophiolite and Iranian magmatic rocks, (3) Mid to Upper Miocene sediments (~14 to 11.2 Ma) were mainly sourced from Sanandaj-Sirjan zone granitoids to the north, and (4) Lower Pliocene (~5 Ma) sediments mainly show Arabian age characteristics, with a minor Eurasian affinity component. Two hypotheses are outlined to highlight the key events: Hypothesis A, previously published by several workers, suggests that the sequence studied lay on the Arabia passive margin and that initial collision occurred prior to 18 Ma; Hypothesis B, modified from the Makran model, which is here preferred, suggests that Paleogene to Upper Miocene sediments were sourced from the northern Neo-Tethyan accretionary complex or Eurasia, and carry no input from Arabia, whereas the Lower Pliocene sample shows a mixed provenance from both Arabia and Eurasia, suggesting that collision occurred between ~11.2 and 5 Ma.

  16. Water Consumption of a Six-Year-Old River Red Gum Plantation in the Southern Zagros Mountains, Iran

    Institute of Scientific and Technical Information of China (English)

    Masoud EDRAKI; Sayyed Ahang KOWSAR; Ali Asghar MEHRBAKHSH; Ali BORDBAR

    2007-01-01

    Water is the most important limiting factor in the development of arid environments;therefore, optimization of water use is a necessity in desert reclamation projects. Evapotranspiration of a 6-year-old river red gum (Eucalyptus camaldulensis Dehnh.) plantation, located in a sedimentation basin of an artificial recharge of the Gareh Bygone Plain groundwater system in Iran's southern Zagros Mountains, was studied during a 7-month period. A neutron moisture probe was used to monitor soil water changes in the root zone. Soil water depletion following rapid drainage for blocks receiving relatively high, medium and low volumes of floodwater were 809.6, 312.4, and 203.1 mm, respectively, for a 150-day period. Soil water potential during most of the study period was below -1.5 MPa. This study proves that river red gum in not a suitable species for desertification control where water conservation is of vital importance. Flood irrigation of trees on 8 Aug.1991 provided the opportunity to throw doubt upon the claim of summer dormancy of river red gum.

  17. Evaluation of vegetation types in the West Zagros (Beiranshahr region as a case study, in Lorestan Province, Iran

    Directory of Open Access Journals (Sweden)

    ATENA ESLAMI FAROUJI

    2016-04-01

    Full Text Available Farouji AE, Khodayari H. 2016. Evaluation of vegetation types in the West Zagros (Beiranshahr region as a case study, in Lorestan Province, Iran. Biodiversita 17: 1-10. The accurate identification of plant communities and their distribution are classical tools for mapping and classification of plants. Plants are strongly sensitive against changing environmental conditions. Moreover, Iran has a special position in Asia which has been creating a diverse ecosystem. Close floristic studies are necessary for precise determination of diversity and uniformity. To determine plant species in different vegetation types in Beiran shahr region, modified multi-scale Whittaker plots were constructed. This studied area was about 20000 ha and located in Northwest to Southwest of Iran. Eighty-nine plots were made in different longitude and latitudes. The minimum and maximum heights were 1101 and 2489 m asl., respectively. Within each modified multi-scale plots, each species was explored. Of 608 species, 498 and 97 are belonging to dicotyledons and monocotyledons, and remained 13 species were Pteridophytes. As measured, Therophyte and Champhyte are the dominant and recessive form of life in studied area. Based on species of each plot and subplots, mean Jaccard's coefficient, number of unique species and mean unique species/plot were estimated for each vegetation type. It is obvious that there is a clear correlation between Slopes of the species-log area curve and Mean number of unique species per plot.

  18. Development and evaluation of local communities incentive programs for improving the traditional forest management:A case study of North-ern Zagros forests, Iran

    Institute of Scientific and Technical Information of China (English)

    Jalal Henareh Khalyani; Manouchehr Namiranian; S. M. Heshmatol Vaezin; Jahangir Feghhi

    2014-01-01

    We examined the local community incentive programs to improve traditional forest management in three forested villages in Baneh city, Kurdistan province in the northern Zagros forests of western Iran. Zagros forests cover 6.07 million ha and support rich plant and animal diversity. Changes in local community social and economic sys-tems and the inefficiency of traditional forest management led to a criti-cal situation in the stability of forest regeneration in recent decades. Due to a shortage of productive and arable lands and resulting unemployment and poverty, people overexploited the Zagros forests. Outside interven-tion in traditional forest management creates conflicts between local peoples and forest management organizations. To achieve sustainable forest management, including forest resources conservation and im-provement of natural resource based livelihoods of communities, it is desirable to implement Forestry Incentive Programs (FIP) based on the important functions of forests. Detailed information on the so-cio-economics of communities, the effect of forests on local livelihoods, and lists of products extracted from the forest were obtained from a sur-vey of local communities though questionnaire, interview and observa-tion. We studied 276 households in three villages and completed 76 ques-tionnaires by householders in the quantitative analysis. Sampling was performed by simple random sampling (SRS). The needs of rural com-munities, such as livestock husbandry, mainly arise from the characteris-tics and environmental features of villages. We identified the driving forces, pressures, status, impacts and responses (DPSIR) to design incen-tive programs, by DPSIR analysis and interaction analysis. Evaluation of local community benefits from forests showed that in order to improve forest management, 319 dollars per year would be needed by each family as an incentive in 2010 to prevent lopping and firewood collecting, the main causes of forest degradation.

  19. Short-term abandonment of human disturbances in Zagros Oak forest ecosystems: Effects on secondary succession of soil seed bank and aboveground vegetation

    Directory of Open Access Journals (Sweden)

    MEHDI HEYDARI

    2014-10-01

    Full Text Available Heydari M, Pothier D, Faramarzi M, Merzaei J. 2014. Short-term abandonment of human disturbances in Zagros Oak forest ecosystems: Effects on secondary succession of soil seed bank and aboveground vegetation. Biodiversitas 15: 147-161. Zagros Oak forests in the west of Iran have been degraded by anthropogenic activities during many years and to fight against this degradation, several management strategies have been implemented. The principal objectives this study were to identify the characteristics of the soil seed bank and the aboveground vegetation that were affected by degradation and short-term abandonment of human disturbances and evaluate the potential of the soil seed bank to restore the degraded types after short-term conservation management. For that, we compared three types of Zagros forest ecosystem with different management regimes: (1 Long term disturbed type as LDT (also used and disturbed at the present, (2 Short-term abandonment of human disturbances as SAD (5 years without human disturbances and an undisturbed control or C (3. We selected three replicates or stands per type. In the aboveground vegetation (ABV, 115, 72 and 51 species were recorded in C, SAD and LDT types, respectively, whereas in the soil seed bank (SSB flora, 33, 19 and 12 plant taxa were observed in C, SAD and LDT types, respectively. The percentage of annuals increased in ABV and decreased in SSB with increasing site degradation with human activities such as animal husbandry in the forest edges. The percentage of perennial and biennial herbs decreased in ABV and increased in SSB with increasing site degradation. The Shannon index of the SSB decreased with increasing site degradation. The average seed density in the SAD type was significantly larger than that of the LDT type. DCA analysis showed that the seed bank flora of SAD and LDT types were relatively similar and differed from that of the C type. This indicates that a full recovery of degraded type in the

  20. Biostratigraphy, facies analysis of Upper Cretaceous-Lower Paleocene strata in south Zagros basin (southwestern Iran)

    Science.gov (United States)

    Afghah, Massih

    2016-07-01

    In this study, two stratigraphic sections of the Tarbur Formation named Kuh-e Gadvan and Kuh-e Tir were selected. The thicknesses of the whole sediments of the sections studied are about 1100 m of which 400 thin sections were studied. Two biozones are determined in Kuh-e Gadvan and three biozones are described in Kuh-e Tir section. According to established biozones, the age of Tarbur Formation of Kuh-e Gadvan section is assigned to Campanian-Maastrichtian and Tarbur Formation age determination shows relation to Maastrichtian-Lower Paleocene in Kuh-e Tir section. Seven major lithofacies are distinguished along two studied stratigraphic columns which are foraminifer-bioclast wackestone, algal-foraminifer- intraclast wackestone, rudist biclast wackestone, bioclast packstone, bioclast-intraclast grainstone, coral and rudist boundstone. According to the recognized lithofacies, paleoenvironment of the Tarbur formation consists of lagoon, open margin of the reef landward, margin of the reef, flat reef, and seaward margin of the reef. Comparison of studied sections allows that geologic setting had been controlled biostratigraphy and facies change.

  1. Tree Crown Delineation on Vhr Aerial Imagery with Svm Classification Technique Optimized by Taguchi Method: a Case Study in Zagros Woodlands

    Science.gov (United States)

    Erfanifard, Y.; Behnia, N.; Moosavi, V.

    2013-09-01

    The Support Vector Machine (SVM) is a theoretically superior machine learning methodology with great results in classification of remotely sensed datasets. Determination of optimal parameters applied in SVM is still vague to some scientists. In this research, it is suggested to use the Taguchi method to optimize these parameters. The objective of this study was to detect tree crowns on very high resolution (VHR) aerial imagery in Zagros woodlands by SVM optimized by Taguchi method. A 30 ha plot of Persian oak (Quercus persica) coppice trees was selected in Zagros woodlands, Iran. The VHR aerial imagery of the plot with 0.06 m spatial resolution was obtained from National Geographic Organization (NGO), Iran, to extract the crowns of Persian oak trees in this study. The SVM parameters were optimized by Taguchi method and thereafter, the imagery was classified by the SVM with optimal parameters. The results showed that the Taguchi method is a very useful approach to optimize the combination of parameters of SVM. It was also concluded that the SVM method could detect the tree crowns with a KHAT coefficient of 0.961 which showed a great agreement with the observed samples and overall accuracy of 97.7% that showed the accuracy of the final map. Finally, the authors suggest applying this method to optimize the parameters of classification techniques like SVM.

  2. Lapse time and frequency-dependent attenuation of coda waves in the Zagros continental collision zone in Southwestern Iran

    Science.gov (United States)

    Rahimi, H.; Hamzehloo, H.

    2008-06-01

    The coda Q, Qc, were estimated for the Zagros continental collision zone in southwestern Iran by analyzing the coda waves of 51 local earthquakes recorded on the three stations of the Iranian National Seismic Network (INSN) with magnitudes of between 3.1 and 4.9 recorded in the region during March and April 2006. Most of the analyzed events are foreshocks and aftershocks of the Darb-e-Astane earthquake which occurred on 31 March 2006 with a magnitude of 6.1 (IIEES). The earthquakes had an epicentral distance of between 120 and 200 km and a focal depth of about 18 km. The Qc values were computed at nine central frequencies of 1.5, 2.0, 3.0, 4.0, 6.0, 8.0, 12.0, 16.0 and 20.0 Hz through eight lapse time windows from 25 to 60 s starting at double the time of the primary S-wave from the origin time using the time-domain coda-decay method of a single backscattering model. In this study the collected data were compared between the events that occurred before and after the main event (foreshocks and aftershocks). The analysis showed a significant variation in the value of coda, Q, for the study region in different lapse times and frequencies. The variation of the quality factor, Qc, before and after the main event was estimated at different lapse time windows to observe its effect with depth. The estimated average frequency-dependent relation of Qc for foreshocks varies from Qc = (144 ± 24)f(0.42 ± 0.23) at 25 s to Qc = (85 ± 10)f(0.92 ± 0.11) at 60 s lapse window time length, respectively. For aftershocks, it varies from Qc = (121 ± 55)f(0.97 ± 0.26) at 25 s to Qc = (212 ± 59)f(0.82 ± 0.15) at 60 s. The averages of Qc in all stations and lapse times window are obtained as Qc = 99f0.84 and Qc = 178f0.86 for foreshocks and aftershocks, respectively. The Q frequency relationship for foreshocks is similar to that for the South Carolina, Koyna, western Anatolia and Aleutian earthquakes, whereas for aftershocks it is similar to the Kumaun, NW Himalaya and Parkfield

  3. Kinematics of a sigmoidal fold and vertical axis rotation in the east of the Zagros Makran syntaxis (southern Iran): Paleomagnetic, magnetic fabric and microtectonic approaches

    Science.gov (United States)

    Smith, B.; Aubourg, C.; Guézou, J. C.; Nazari, H.; Molinaro, M.; Braud, X.; Guya, N.

    2005-12-01

    The Zagros Simple Fold Belt is characterized by elongated, curved, or sigmoidal folds. The trend of these structures together with the structural style, change suddenly across the Zagros-Makran syntaxis which separates the continental collision domain of Zagros from the oceanic subduction one in Makran. This work focuses on the Minab anticline, outcropping in the easternmost part of Zagros. In order to understand the kinematics of a sigmoidal fold and underscore possible vertical axis rotations in the eastern side of the syntaxis, we performed a joint study of magnetic fabric, microtectonics and paleomagnetism of the northern termination of this fold. The two limbs have been sampled (7 sites, 134 samples) along three cross-sections corresponding to three different orientations of the fold axis. The rocks are weakly deformed fine-grained Mio-Pliocene reddish siltstones. The shortening directions deduced from both magnetic fabric analysis and microtectonic observations are consistent with each other, they are horizontal and roughly perpendicular to the local fold axis, following the torsion of the fold hinge line, and indicating a tectonic origin of the magnetic fabric. Rockmagnetic analyses (thermomagnetic curves, hysteresis loops) point to the presence of magnetite in the PSD and MD ranges as the main magnetic carriers, together with a minor contribution from hematite. Apart from a post-tilting sub-actual VRM and/or CRM (component A), paleomagnetic analyses yield mainly two pre-tilting magnetization components: Component B is carried by magnetite, spanning the intermediate to high unblocking temperature range (300 °C ≤ Tubs ≤ 580 °C). Component C has unblocking temperatures characteristic of hematite (580 °C ≤ Tubs ≤ 680 °C). Both are ante-folding, based on positive reversal and fold tests, inside each of the cross-section but also for the three sections together. However, because component C is biased by some inclination flattening, only component B is

  4. Revealing the significance and polyphase tectonothermal evolution of a major metamorphic unit in an orogen: the central Sanandaj-Sirjan zone, Zagros Mts., Iran

    Science.gov (United States)

    Shakerardakani, Farzaneh; Neubauer, Franz; Genser, Johann; Liu, Xiaoming; Dong, Yunpeng; Monfaredi, Behzad; Benroider, Manfred; Finger, Fritz; Waitzinger, Michael

    2016-04-01

    The Dorud-Azna region in the central Sanandaj-Sirjan metamorphic belt plays a key role in promoting the tectonic evolution of Zagros orogen, within the frame of the Arabia-Eurasia collision zone. From footwall to hangingwall, structural data combined with the U-Pb zircon and extensive 40Ar-39Ar mineral dating survey demonstrate three metamorphosed tectonic units, which include: (1) The Triassic June complex is metamorphosed within greenschist facies conditions, overlain by (2) the amphibolite-grade metamorphic Galeh-Doz orthogneiss, which is intruded by mafic dykes, and (3) the Amphibolite-Metagabbro unit. To the east, these units were intruded by the Jurassic Darijune gabbro. We present U-Pb detrital zircon ages of a garnet-micaschist from the Amphibolite-Metagabbro unit, which yield six distinctive age groups, including a previously unrecognized Late Grenvillian age population at ~0.93 to 0.99 Ga. We speculate that this unique Late Grenvillian group coupled with biogeographic evidence suggests either relationship with the South China craton or to the "Gondwana superfan". The laser ablation ICP-MS U-Pb zircon ages of 608 ± 18 Ma and 588 ± 41 Ma of the granitic Galeh-Doz orthogneiss reveals a Panafrican basement same as known from the Yazd block of Central Iran. Geochemistry and Sr-Nd isotopes of alkaline and subalkaline mafic dykes within the Galeh-Doz orthogneiss show OIB-type to MORB-type and indicate involvement of both depleted and enriched sources for its genesis. The new 40Ar-39Ar amphibole age of ca. 322.2 ± 3.9 Ma from the alkaline mafic dyke implies Carboniferous cooling age after intrusion. The metagabbros (including the Dare-Hedavand metagabbro with a 206Pb/238U age of 314.6 ± 3.7 Ma) and amphibolites with E-MORB geochemical signature of the Amphibolite-Metagabbro unit represent an Upper Paleozoic rift. The geochemical composition of the Triassic greenschist facies metamorphosed June complex, implying formation in a same, but younger tectonic

  5. Phenetic relationships among natural population accessions of Glycyrrhiza glabra L. (Fabaceae in central Zagros region of Iran, based on quantitative morphology, flavonoids and glycyrrhizin contents data

    Directory of Open Access Journals (Sweden)

    Majid Sharifi-Tehrani

    2013-01-01

    Full Text Available Phenetic relationships among thirty five accessions from natural populations of two varieties of Glycyrrhiza glabra in central Zagros region of Iran were studied. Twenty one quantitative morphological characters were measured for twenty seven accessions. PCO, clustering, K-means and MDS analyses were performed on morphological dataset. Polar flavonoid constituents of twenty four accessions were extracted, purified using TLC and characterized at the skeleton class level. Glycyrrhizin contents of rhizomes in twenty four accessions were quantified using image processing methods. Results of multivariate analysis of both morphological and flavonoid spot profile data showed that accessions could be partitioned into two main groups based on geographical locality of the populations. The most variable morphological trait based on CV values, was seed area and the least variable one was Legume width in the widest portion. Accessions of both varieties produced various flavonoids of class flavones and flavonols. Seven flavonoid constituents from the two varieties were separated based on different Rf values. The results revealed that there were moderate (not prominent levels of variation between the studied accessions. Separation of the varieties based on the single qualitative character in the available literature, was confirmed. Rhizomes of both varieties showed similar amounts of glycyrrhizin and almost similar types of flavonoids in their TLC profiles, suggesting that both were equivalent as herbal drugs in folk medicine.

  6. New Criteria to Assess Seismic and Rock Burst Hazard in Coal Mines / Nowe Kryteria Dla Oceny Zagrożenia Sejsmicznego I Tąpaniami W Kopalniach Węgla Kamiennego

    Science.gov (United States)

    Mutke, Grzegorz; Dubiński, Józef; Lurka, Adam

    2015-09-01

    The paper presents new criteria of seismic and rock burst hazard assessment in Polish hard coal mines where longwall mining system is common practice. The presented criteria are based on the results of continuous recording of seismic events and analysis of selected seismological parameters: spatial location of seismic event in relation to mining workings, seismic energy, seismic energy release per unit coal face advance, b-value of Gutenberg-Richter law, seismic energy index EI, seismic moment M0, weighted value of peak particle velocity PPVW. These parameters are determined in a moving daily time windows or time windows with fixed number of seismic tremors. Time changes of these parameters are then compared with mean value estimated in the analyzed area. This is the basis to indicate the zones of high seismic and rock burst hazard in specific moment in time during mining process. Additionally, the zones of high seismic and rock burst hazard are determined by utilization of passive seismic tomography method. All the calculated seismic parameters in moving time windows are used to quantify seismic and rock burst hazard by four level scales. In practice, assessment of seismic and rock burst hazard is used to make daily decision about using rock burst prevention activities and correction of further exploitation of monitored coal panel. Zagrożenie sejsmiczne i związane z nim genetycznie zagrożenie tąpnięciem w dalszym ciągu należą do najgroźniejszych zagrożeń naturalnych występujących w polskich kopalniach węgla kamiennego. W ostatnich latach w kopalniach Górnośląskiego Zagłębia Węglowego (GZW) rocznie rejestrowano 1000÷1500 wstrząsów o energii sejsmicznej Es ≥ 1·105J (magnituda lokalna ML ≥ 1.7), a najsilniejsze z nich osiągały energię Es = 4 ·109J (ML = 4.1). W latach 1991-2010 odnotowano w GZW 101 tąpnięć, z których około 66% miało miejsce w wyrobiskach chodnikowych, powodując ich uszkodzenia lub całkowite zniszczenie, a w

  7. Detrital zircon U-Pb and (U-Th)/He double-dating of Upper Cretaceous-Cenozoic Zagros foreland basin strata in the Kurdistan Region of northern Iraq

    Science.gov (United States)

    Barber, D. E.; Stockli, D. F.; Koshnaw, R. I.; Horton, B. K.; Tamar-Agha, M. Y.; Kendall, J. J.

    2014-12-01

    The NW Zagros orogen is the result of the multistage collisional history associated with Late Cretaceous-Cenozoic convergence of the Arabian and Eurasian continents and final closure of Neotethys. Siliciclastic strata preserved within a ~400 km segment of the NW Zagros fold-thrust belt and foreland basin in the Iraqi Kurdistan Region (IKR) provide a widespread record of exhumation and sedimentation. As a means of assessing NW Zagros foreland basin evolution and chronostratigraphy, we present coupled detrital zircon (DZ) U-Pb and (U-Th)/He geo-thermochronometric data of Upper Cretaceous to Pliocene siliciclastic strata from the Duhok, Erbil, and Suleimaniyah provinces of IKR. LA-ICP-MS U-Pb age analyses reveal that the foreland basin fill in IKR in general was dominantly derived from Pan-African/Arabian-Nubian, Peri-Gondwandan, Eurasian, and Cretaceous volcanic arc terrenes. However, the provenance of these strata varies systematically along strike and through time, with an overall increase in complexity upsection. DZ age distribution of Paleocene-Eocene strata is dominated by a ~95 Ma grain age population, likely sourced from the Late Cretaceous Hassanbag-Bitlis volcanic arc complex along the northern margin of Arabia. In contrast, DZ U-Pb age distributions of Neogene strata show a major contribution derived from various Eurasian (e.g., Iranian, Tauride, Pontide; ~45, 150, 300 Ma) and Pan-African (~550, 950 Ma) sources. The introduction of Eurasian DZ ages at the Paleogene-Neogene transition likely records the onset of Arabian-Eurasian collision. Along strike to the southeast, the DZ U-Pb spectra of Neogene strata show a decreased percentage of Pan-African, Peri-Gondwandan, Tauride, and Ordovician ages, coupled with a dramatic increase in 40-50 Ma DZ ages that correspond to Urumieh-Dokhtar magmatic rocks in Iran. Combined with paleocurrent data, this suggests that Neogene sediments were transported longitudinally southeastward through an unbroken foreland basin

  8. Mechanical restoration of large-scale folded multilayers using the finite element method: Application to the Zagros Simply Folded Belt, N-Iraq

    Science.gov (United States)

    Frehner, Marcel; Reif, Daniel; Grasemann, Bernhard

    2010-05-01

    There are a large number of numerical finite element studies concerned with modeling the evolution of folded geological layers through time. This body of research includes many aspects of folding and many different approaches, such as two- and three-dimensional studies, single-layer folding, detachment folding, development of chevron folds, Newtonian, power-law viscous and more complex rheologies, influence of anisotropy, pure-shear, simple-shear and other boundary conditions and so forth. In recent years, studies of multilayer folding emerged, thanks to more advanced mesh generator software and increased computational power. Common to all of these studies is the fact that they consider a forward directed time evolution, as in nature. Very few studies use the finite element method for reverse-time simulations. In such studies, folded geological layers are taken as initial conditions for the numerical simulation. The folding process is reversed by changing the signs of the boundary conditions that supposedly drove the folding process. In such studies, the geometry of the geological layers before the folding process is searched and the amount of shortening necessary for the final folded geometry can be calculated. In contrast to a kinematic or geometric fold restoration procedure, the described approach takes the mechanical behavior of the geological layers into account, such as rheology and the relative strength of the individual layers. This approach is therefore called mechanical restoration of folds. In this study, the concept of mechanical restoration is applied to a two-dimensional 50km long NE-SW-cross-section through the Zagros Simply Folded Belt in Iraqi Kurdistan, NE from the city of Erbil. The Simply Folded Belt is dominated by gentle to open folding and faults are either absent or record only minor offset. Therefore, this region is ideal for testing the concept of mechanical restoration. The profile used is constructed from structural field measurements

  9. The intra-oceanic Cretaceous (~ 108 Ma) Kata-Rash arc fragment in the Kurdistan segment of Iraqi Zagros suture zone: Implications for Neotethys evolution and closure

    Science.gov (United States)

    Ali, Sarmad A.; Ismail, Sabah A.; Nutman, Allen P.; Bennett, Vickie C.; Jones, Brian G.; Buckman, Solomon

    2016-09-01

    The Kata-Rash arc fragment is an allochthonous thrust-bound body situated near Penjween, 100 km northeast of Sulymannia city, Kurdistan Region, within the Iraqi portion of the Zagros suture zone. It forms part of the suprasubduction zone 'Upper Allochthon' terranes (designated as the Gimo-Qandil Group), which is dominated by calc-alkaline andesite and basaltic-andesite, rhyodacite to rhyolite, crosscut by granitic, granodioritic, and dioritic dykes. Previously, rocks of the Kata-Rash arc fragment were interpreted as a part of the Eocene Walash volcanic group. However, SHRIMP zircon U-Pb dates on them of 108.1 ± 2.9 Ma (Harbar volcanic rocks) and 107.7 ± 1.9 Ma (Aulan intrusion) indicate an Albian-Cenomanian age, which is interpreted as the time of igneous crystallisation. The Aulan intrusion zircons have initial εHf values of + 8.6 ± 0.2. On a Nb/Yb-Th/Yb diagram, all Kata-Rash samples fall within the compositional field of arc-related rocks, i.e. above the mid-ocean-ridge basalt (MORB)-ocean island basalt (OIB) mantle array. Primitive-mantle-normalised trace-element patterns for the Kata-Rash samples show enrichment in the large ion lithophile elements and depletion in the high-field-strength elements supporting their subduction-related character. Low Ba/La coupled with low La/Yb and Hf/Hf* 3000 km continuity of Cretaceous arc activity (Oman to Cyprus), that consumed Neotethyian oceanic crust between Eurasia and the Gondwanan fragment Arabia.

  10. Selected Methods of Rock Structure Disintegration to Control Mining Hazards / Wybrane Metody Dezintegracji Struktury Skał Dla Zwalczania Zagrożeń Górniczych

    Science.gov (United States)

    Kabiesz, Józef; Lurka, Adam; Drzewiecki, Jan

    2015-09-01

    Natural hazards are inseparable element of underground mining, particularly of coal mining process. They are combated on a regular basis by many measures and effectiveness of these measures determines work safety in mines. Attempts to improve the effectiveness, presented in the paper is based on interference of seismic waves generated by blasting in a selected area of the rock mass and on modification of blasting technology. Preliminary results of detonating classical and new type of explosives in specific temperature and pressure conditions are analyzed. Theoretical and practical consideration of obtaining an interference effect of seismic waves is discussed. A device for making systems of starting notches and a construction of a chamber to test explosives are presented. Nieodłącznym elementem podziemnego górnictwa, szczególnie węglowego, są zagrożenia naturalne. Ich zwalczanie jest codzienną praktyką, a jego skuteczność decydująco wpływa na bezpieczeństwo pracy. Przedstawione w artykule próby poprawy tej skuteczności obejmują badania efektu nakładania się w wybranym obszarze górotworu drgań generowanych robotami strzałowymi oraz informacje o próbach modyfikacji strzelniczych technik szczelinowania skał, a także wstępne wyniki badania charakterystyk eksplozji klasycznych i nowych materiałów wybuchowych w nietypowych warunkach temperatur i ciśnienia. Omówiono między innymi teoretyczne i praktyczne warunki uzyskiwania efektu interferencji drgań oraz przedstawiono urządzenie do wykonywania systemów tzw. szczelin zarodnikowych i konstrukcję komory będącej elementem stanowiska do badania MW.

  11. Folding style controlled by intermediate decollement thickness change in the Lurestan region (NW of the Zagros fold-and-thrust belt), using analogue models

    Science.gov (United States)

    Farzipour Saein, Ali

    2016-07-01

    The basal and intermediate decollements play an important role in structural style of fold-and-thrust belts. The decollement units, or different mechanical stratigraphy within the rock units, are not uniform throughout the ZFTB and show a strong spatial variation. The Lurestan region with varied thickness of the intermediate decollement in its northern and southern parts is one of the most important parts of the Zagros fold-and-thrust belt, regarding its hydrocarbon exploration-extraction projects. Thickness variation of the intermediate decollement in different parts of the Lurestan region allows us to address its role on folding style. Based on scaled analogue modeling, this study outlines the impact of thickness and facies variation of sedimentary rocks in the northern and southern parts of this region on folding style. Two models simulated the mechanical stratigraphy and its consequent different folding styles of the northern and southern parts of the region. In the models, only thickness of the intermediate decollement (thick and thin) for the northern and southern parts of the Lurestan region was varied. Detached minor folds above the intermediate decollement were created in response to the presence of the thicker intermediate decollement, northern part of the study area, which consequently deformed complexly and disharmonically folded, in contrast to polyharmonic folding style in the section, compared to polyharmonic folding style in the southern part, where thin intermediate decollement exists. The model results documented that thickness variation of intermediate decollement levels could explain complex and different folding styles in natural examples which must be taken into account for hydrocarbon exploration throughout these areas.

  12. 3D Reconstruction of geological structures based on remote sensing data: example from Anaran anticline, Lurestan province, Zagros folds and thrust belt, Iran.

    Science.gov (United States)

    Snidero, M.; Amilibia, A.; Gratacos, O.; Muñoz, J. A.

    2009-04-01

    This work presents a methodological workflow for the 3D reconstruction of geological surfaces at regional scale, based on remote sensing data and geological maps. This workflow has been tested on the reconstruction of the Anaran anticline, located in the Zagros Fold and Thrust belt mountain front. The used remote sensing data-set is a combination of Aster and Spot images as well as a high resolution digital elevation model. A consistent spatial positioning of the complete data-set in a 3D environment is necessary to obtain satisfactory results during the reconstruction. The Aster images have been processed by the Optimum Index Factor (OIF) technique, in order to facilitate the geological mapping. By pansharpening of the resulting Aster image with the SPOT panchromatic one we obtain the final high-resolution image used during the 3D mapping. Structural data (dip data) has been acquired through the analysis of the 3D mapped geological traces. Structural analysis of the resulting data-set allows us to divide the structure in different cylindrical domains. Related plunge lines orientation has been used to project data along the structure, covering areas with little or no information. Once a satisfactory dataset has been acquired, we reconstruct a selected horizon following the dip-domain concept. By manual editing, the obtained surfaces have been adjusted to the mapped geological limits as well as to the modeled faults. With the implementation of the Discrete Smooth Interpolation (DSI) algorithm, the final surfaces have been reconstructed along the anticline. Up to date the results demonstrate that the proposed methodology is a powerful tool for 3D reconstruction of geological surfaces when working with remote sensing data, in very inaccessible areas (eg. Iran, China, Africa). It is especially useful in semiarid regions where the structure strongly controls the topography. The reconstructed surfaces clearly show the geometry in the different sectors of the structure

  13. The intra-oceanic Cretaceous (~ 108 Ma) Kata-Rash arc fragment in the Kurdistan segment of Iraqi Zagros suture zone: Implications for Neotethys evolution and closure

    Science.gov (United States)

    Ali, Sarmad A.; Ismail, Sabah A.; Nutman, Allen P.; Bennett, Vickie C.; Jones, Brian G.; Buckman, Solomon

    2016-09-01

    The Kata-Rash arc fragment is an allochthonous thrust-bound body situated near Penjween, 100 km northeast of Sulymannia city, Kurdistan Region, within the Iraqi portion of the Zagros suture zone. It forms part of the suprasubduction zone 'Upper Allochthon' terranes (designated as the Gimo-Qandil Group), which is dominated by calc-alkaline andesite and basaltic-andesite, rhyodacite to rhyolite, crosscut by granitic, granodioritic, and dioritic dykes. Previously, rocks of the Kata-Rash arc fragment were interpreted as a part of the Eocene Walash volcanic group. However, SHRIMP zircon U-Pb dates on them of 108.1 ± 2.9 Ma (Harbar volcanic rocks) and 107.7 ± 1.9 Ma (Aulan intrusion) indicate an Albian-Cenomanian age, which is interpreted as the time of igneous crystallisation. The Aulan intrusion zircons have initial εHf values of + 8.6 ± 0.2. On a Nb/Yb-Th/Yb diagram, all Kata-Rash samples fall within the compositional field of arc-related rocks, i.e. above the mid-ocean-ridge basalt (MORB)-ocean island basalt (OIB) mantle array. Primitive-mantle-normalised trace-element patterns for the Kata-Rash samples show enrichment in the large ion lithophile elements and depletion in the high-field-strength elements supporting their subduction-related character. Low Ba/La coupled with low La/Yb and Hf/Hf* temperature melt from subducted slab sediment, in an oceanic setting. This mechanism can explain the sub-DM initial εHf value, without the need to invoke melting of significantly older (continental) crust in an Andean setting. We interpret the Kata-Rash igneous rocks as a fragment of the Late Cretaceous suprasubduction zone system (named here the Kata-Rash arc) that most likely developed within the Neotethys Ocean rather than at a continental margin. Subsequently during the latest Cretaceous to Paleocene, the arc was accreted to the northern margin of the Arabian plate. The results indicate a > 3000 km continuity of Cretaceous arc activity (Oman to Cyprus), that consumed

  14. Use of Remote Sensing Data and GIS Tools for Seismic Hazard Assessment for Shallow Oilfields and its Impact on the Settlements at Masjed-i-Soleiman Area, Zagros Mountains, Iran

    Directory of Open Access Journals (Sweden)

    Hojjat Ollah Safari

    2010-05-01

    Full Text Available Masjed-i-Soleiman (MIS is situated in the northern part of the Dezful embayment, which is in the Zagros fold–thrust belt with high seismic activities. MIS faces a shallow buried anticline, formed by the shallowest oilfield with a thick gas cap. The cap rocks of this oilfield are highly fractured, which has resulted in leakages from the gas cap. In this paper, we have used remote sensing techniques and image interpretation for the identification of the Niayesh, Lahbari, Andika and MIS fault zones in the studied area. Further, the study exploited seismic potential mapping using the remote sensing techniques. The relationships between the structural controls and localized gas leakage are assessed within the GIS environment. Additionally, field observation data corroborated that the leakages (and seepages are smashed within the intersection of Niayesh and MIS fault zone, which belongs to the high fractured hinge zone of the MIS anticline. As a result, the reactivation of these active faults may cause large earthquakes with a maximum magnitude of between 6.23 < Ms < 7.05 (Richter scale and maximum horizontal acceleration 0.26 < a < 0.55 g. Finally, the authors concluded that this anticipated earthquake may cause large scale fracturing of cap rocks, releasing a large volume of H2S gas from the uppermost layer of the reservoir.

  15. Corrigendum to "Facies analysis and diagenetic features of the Aptian Dariyan Formation in Zagros Fold-Thrust Belt, SW Iran" [J. Afr. Earth Sci. 100 (2014) 598-613

    Science.gov (United States)

    Haghighi, Arash Shaabanpour; Sahraeyan, Mohammad

    2015-03-01

    Paragraph 3: Lagoonal facies are highly variable but contain abundant imperforated tests of foraminifera (miliolids and orbitolinids). Towards the shoal, imperforated foraminifers and perforated foraminifera (nautiloculinids, textolarids and rotalids) occur together.

  16. A study on the genetic model of hydrothermal dolomitization in Taq Taq oilfield, Kurdistan region,Iraq-taking oilfield A in the Cretaceous in Zagros Basin as an example%热液白云岩发育模式--以扎格罗斯盆地白垩系A油田为例

    Institute of Scientific and Technical Information of China (English)

    张涛; 苏玉山; 佘刚; 艾合买提江; 张德民

    2015-01-01

    Based on core petrographic description,fracture statistics,comprehensive interpretation of seismic and logging data,analogues with other confirmed examples,this paper analyzed the identification marks,development timing,genetic model and distribution of the hydrothermal dolomitization and its alteration on the reservoir quality,so as to analyze the abnormal distribution of dolomite in the Kometan Formation of the Cretaceous oilfield A in Zagros Basin.The most part of Kometan Formation and the lower part of the Shiranish Formation in two wells were altered by hydrothermal dolomitiza-tion.The matrix limestone there was replaced by hydrothermal flow with the crystal intergrowth, half automorphic, and coarse grain dolomite.Early extensional fractures were filled with saddle dolomite and anhydrite.Celestine-saddle dolo-mite-anhydrite is the main hydrothermal mineral assemblage and can be used to identify the hydrothermal origin.The hy-drothermal dolomitization preferentially flow upwards along the extensional and transtensional fault systems,where dolo-mitization mainly occurs on the hanging walls( graben) and extends laterally in the porous and permeable layers.In this case,the geometry of altered rocks was with stratification,the limestone strata near the fractured zone were also altered by hydrothermal dolomitization which display great irregularity.The alteration of hydrothermal dolomitization on reservoir is complicated.The dolostone formed along the main fault has lower matrix porosity than dolomite a little far from main faults,because over-dolomitization usually happened in the position with more active hydrothermal fluid flow.Local reser-voir quality is obviously improved with matrix porosity of about 6%.The dolomite is generally more fractured than the limestone,so dolomitization has greatly increased the fracture density and improve the flow capacity of the reservoir.This study is significant for reservoir modeling and production strategies.%针对扎格罗

  17. Modeling Oligo-Miocence channel sands (Dezful Embayment, SW Iran): an integrated facies classification workflow

    Science.gov (United States)

    Heydari, Mostafa; Maddahi, Iradj; Moradpour, Mehran; Esmaeilpour, Sajjad

    2014-08-01

    This study has been conducted on Mansuri onshore oilfield located in Dezful Embayment, south-west Iran. One of the hydrocarbon-bearing formations is a Oligo-Miocene Asmari formation—the most prolific Iranian reservoir rock. Like many other oilfields in the area, the trap in this field is deemed structural (anticline), formed during the collision of the Arabian plate with the Iranian plate and the folding of Neotethys deposits with a NW-SE trend. This study integrates three different quantitative studies from geology, geophysics and petrophysics disciplines to quantitate ‘the qualitative study of seismic facies analysis based on trace shapes and 3D multi-attribute clustering’. First, stratigraphic sequences and seismic detectable facies were derived at one well location using the available high resolution core facies analysis and depositional environment assessment reports. Paleo and petrophysical logs from other wells were subsequently used for the extrapolation of stratigraphic sequences interpreted at the first well. Utilizing lithology discrimination obtained by wire-line log interpretation, facies were extrapolated to all wells in the area. Seismic 3D attribute analysis and seismic facies classification established a 3D facies volume accordingly, which was finally calibrated to geological facies at well locations. The ultimate extracted facies-guided geobody shows that good reservoir-quality channel sands have accumulated with NW/SE elongation at the ridge of the structure. As a result, this type of geometry has created a stratigraphic/structural hydrocarbon trap in this oilfield. Moreover, seismic facies analysis shows that buried channels do not parallel the predominant Arabian plate-originated channels (with SW-NE trends) in SW Zagros and are locally swerved in this area.

  18. Stellar formation

    CERN Document Server

    Reddish, V C

    1978-01-01

    Stellar Formation brings together knowledge about the formation of stars. In seeking to determine the conditions necessary for star formation, this book examines questions such as how, where, and why stars form, and at what rate and with what properties. This text also considers whether the formation of a star is an accident or an integral part of the physical properties of matter. This book consists of 13 chapters divided into two sections and begins with an overview of theories that explain star formation as well as the state of knowledge of star formation in comparison to stellar structure

  19. Galaxy formation

    International Nuclear Information System (INIS)

    Galaxy formation is at the forefront of observation and theory in cosmology. An improved understanding is essential for improving our knowledge both of the cosmological parameters, of the contents of the universe, and of our origins. In these lectures intended for graduate students, galaxy formation theory is reviewed and confronted with recent observational issues. In lecture 1, the following topics are presented: star formation considerations, including IMF, star formation efficiency and star formation rate, the origin of the galaxy luminosity function, and feedback in dwarf galaxies. In lecture 2, we describe formation of disks and massive spheroids, including the growth of supermassive black holes, negative feedback in spheroids, the AGN-star formation connection, star formation rates at high redshift and the baryon fraction in galaxies.

  20. Galaxy formation

    CERN Document Server

    Silk, Joseph; Dvorkin, Irina

    2015-01-01

    Galaxy formation is at the forefront of observation and theory in cosmology. An improved understanding is essential for improving our knowledge both of the cosmological parameters, of the contents of the universe, and of our origins. In these lectures intended for graduate students, galaxy formation theory is reviewed and confronted with recent observational issues. In Lecture 1, the following topics are presented: star formation considerations, including IMF, star formation efficiency and star formation rate, the origin of the galaxy luminosity function, and feedback in dwarf galaxies. In Lecture 2, we describe formation of disks and massive spheroids, including the growth of supermassive black holes, negative feedback in spheroids, the AGN-star formation connection, star formation rates at high redshift and the baryon fraction in galaxies.

  1. Soil formation.

    NARCIS (Netherlands)

    Breemen, van N.; Buurman, P.

    1998-01-01

    Soil Formation deals with qualitative and quantitative aspects of soil formation (or pedogenesis) and the underlying chemical, biological, and physical processes. The starting point of the text is the process - and not soil classification. Effects of weathering and new formation of minerals, mobilis

  2. Galaxy Formation

    DEFF Research Database (Denmark)

    Sparre, Martin

    Galaxy formation is an enormously complex discipline due to the many physical processes that play a role in shaping galaxies. The objective of this thesis is to study galaxy formation with two different approaches: First, numerical simulations are used to study the structure of dark matter and how...... galaxies form stars throughout the history of the Universe, and secondly it is shown that observations of gamma-ray bursts (GRBs) can be used to probe galaxies with active star formation in the early Universe. A conclusion from the hydrodynamical simulations is that the galaxies from the stateof-the-art...

  3. Bulge Formation

    CERN Document Server

    Combes, F

    1999-01-01

    The currently discussed theories of bulge formation are reviewed, including the primordial scenario, where bulges form rapidly and then accrete disks, the secular scenario, where bulges are formed by dynamical evolution of disks through bars and galaxy interactions, and some combinations of both, where formation of bulges and disks are more continuous and interleaved. The various scenarios make specific predictions about the relative masses, angular momenta, colours, metallicities of bulges relative to disks, and the bulge-to-disk ratio as a function of time. Dynamical processes relevant to the formation of bulges (bar instabilities, mergers) are described and tested against observed statistics. Current data suggest a dynamical feedback from gravitational instabilities in bulge and disk formation. It is very difficult to discriminate between the various scenarios from surveys at z=0 only, and observations at high redshift are presently the best hope for large progress.

  4. Cement Formation

    DEFF Research Database (Denmark)

    Telschow, Samira; Jappe Frandsen, Flemming; Theisen, Kirsten;

    2012-01-01

    Cement production has been subject to several technological changes, each of which requires detailed knowledge about the high multiplicity of processes, especially the high temperature process involved in the rotary kiln. This article gives an introduction to the topic of cement, including......−liquid reactions are discussed, as are the influences of particles sizes on clinker phase formation. Furthermore, a mechanism for clinker phase formation in an industrial rotary kiln reactor is outlined....

  5. Star formation

    Energy Technology Data Exchange (ETDEWEB)

    Woodward, P.R.

    1978-09-27

    Theoretical models of star formation are discussed beginning with the earliest stages and ending in the formation of rotating, self-gravitating disks or rings. First a model of the implosion of very diffuse gas clouds is presented which relies upon a shock at the edge of a galactic spiral arm to drive the implosion. Second, models are presented for the formation of a second generation of massive stars in such a cloud once a first generation has formed. These models rely on the ionizing radiation from massive stars or on the supernova shocks produced when these stars explode. Finally, calculations of the gravitational collapse of rotating clouds are discussed with special focus on the question of whether rotating disks or rings are the result of such a collapse. 65 references.

  6. Star formation

    International Nuclear Information System (INIS)

    Theoretical models of star formation are discussed beginning with the earliest stages and ending in the formation of rotating, self-gravitating disks or rings. First a model of the implosion of very diffuse gas clouds is presented which relies upon a shock at the edge of a galactic spiral arm to drive the implosion. Second, models are presented for the formation of a second generation of massive stars in such a cloud once a first generation has formed. These models rely on the ionizing radiation from massive stars or on the supernova shocks produced when these stars explode. Finally, calculations of the gravitational collapse of rotating clouds are discussed with special focus on the question of whether rotating disks or rings are the result of such a collapse. 65 references

  7. Galaxy formation.

    Science.gov (United States)

    Peebles, P J

    1998-01-01

    It is argued that within the standard Big Bang cosmological model the bulk of the mass of the luminous parts of the large galaxies likely had been assembled by redshift z approximately 10. Galaxy assembly this early would be difficult to fit in the widely discussed adiabatic cold dark matter model for structure formation, but it could agree with an isocurvature version in which the cold dark matter is the remnant of a massive scalar field frozen (or squeezed) from quantum fluctuations during inflation. The squeezed field fluctuations would be Gaussian with zero mean, and the distribution of the field mass therefore would be the square of a random Gaussian process. This offers a possibly interesting new direction for the numerical exploration of models for cosmic structure formation.

  8. Pattern Formation

    Science.gov (United States)

    Hoyle, Rebecca

    2006-03-01

    From the stripes of a zebra and the spots on a leopard's back to the ripples on a sandy beach or desert dune, regular patterns arise everywhere in nature. The appearance and evolution of these phenomena has been a focus of recent research activity across several disciplines. This book provides an introduction to the range of mathematical theory and methods used to analyse and explain these often intricate and beautiful patterns. Bringing together several different approaches, from group theoretic methods to envelope equations and theory of patterns in large-aspect ratio-systems, the book also provides insight behind the selection of one pattern over another. Suitable as an upper-undergraduate textbook for mathematics students or as a fascinating, engaging, and fully illustrated resource for readers in physics and biology, Rebecca Hoyle's book, using a non-partisan approach, unifies a range of techniques used by active researchers in this growing field. Accessible description of the mathematical theory behind fascinating pattern formation in areas such as biology, physics and materials science Collects recent research for the first time in an upper level textbook Features a number of exercises - with solutions online - and worked examples

  9. Common File Formats.

    Science.gov (United States)

    Mills, Lauren

    2014-03-21

    An overview of the many file formats commonly used in bioinformatics and genome sequence analysis is presented, including various data file formats, alignment file formats, and annotation file formats. Example workflows illustrate how some of the different file types are typically used.

  10. Extreme Star Formation

    OpenAIRE

    Turner, JL

    2010-01-01

    Extreme star formation includes star formation in starbursts and regions forming super star clusters. We survey the current problems in our understanding of the star formation process in starbursts and super star clusters - initial mass functions, cluster mass functions, star formation efficiencies, and radiative feedback into molecular clouds - that are critical to our understanding of the formation and survival of large star clusters, topics that will be the drivers of the observations of t...

  11. Formate Formation and Formate Conversion in Biological Fuels Production

    Directory of Open Access Journals (Sweden)

    Bryan R. Crable

    2011-01-01

    Full Text Available Biomethanation is a mature technology for fuel production. Fourth generation biofuels research will focus on sequestering CO2 and providing carbon-neutral or carbon-negative strategies to cope with dwindling fossil fuel supplies and environmental impact. Formate is an important intermediate in the methanogenic breakdown of complex organic material and serves as an important precursor for biological fuels production in the form of methane, hydrogen, and potentially methanol. Formate is produced by either CoA-dependent cleavage of pyruvate or enzymatic reduction of CO2 in an NADH- or ferredoxin-dependent manner. Formate is consumed through oxidation to CO2 and H2 or can be further reduced via the Wood-Ljungdahl pathway for carbon fixation or industrially for the production of methanol. Here, we review the enzymes involved in the interconversion of formate and discuss potential applications for biofuels production.

  12. Star Formation in Galaxies

    Science.gov (United States)

    1987-01-01

    Topics addressed include: star formation; galactic infrared emission; molecular clouds; OB star luminosity; dust grains; IRAS observations; galactic disks; stellar formation in Magellanic clouds; irregular galaxies; spiral galaxies; starbursts; morphology of galactic centers; and far-infrared observations.

  13. Star Formation for Predictive Primordial Galaxy Formation

    CERN Document Server

    Milosavljevic, Milos

    2015-01-01

    The elegance of inflationary cosmology and cosmological perturbation theory ends with the formation of the first stars and galaxies, the initial sources of light that launched the phenomenologically rich process of cosmic reionization. Here we review the current understanding of early star formation, emphasizing unsolved problems and technical challenges. We begin with the first generation of stars to form after the Big Bang and trace how they influenced subsequent star formation. The onset of chemical enrichment coincided with a sharp increase in the overall physical complexity of star forming systems. Ab-initio computational treatments are just now entering the domain of the predictive and are establishing contact with local observations of the relics of this ancient epoch.

  14. Star Formation for Predictive Primordial Galaxy Formation

    Science.gov (United States)

    Milosavljević, Miloš; Safranek-Shrader, Chalence

    The elegance of inflationary cosmology and cosmological perturbation theory ends with the formation of the first stars and galaxies, the initial sources of light that launched the phenomenologically rich process of cosmic reionization. Here we review the current understanding of early star formation, emphasizing unsolved problems and technical challenges. We begin with the first generation of stars to form after the Big Bang and trace how they influenced subsequent star formation. The onset of chemical enrichment coincided with a sharp increase in the overall physical complexity of star forming systems. Ab-initio computational treatments are just now entering the domain of the predictive and are establishing contact with local observations of the relics of this ancient epoch.

  15. The Conic Benchmark Format

    DEFF Research Database (Denmark)

    Friberg, Henrik A.

    This document constitutes the technical reference manual of the Conic Benchmark Format with le extension: .cbf or .CBF. It unies linear, second-order cone (also known as conic quadratic) and semidenite optimization with mixed-integer variables. The format has been designed with benchmark libraries...... in mind, and therefore focuses on compact and easily parsable representations. The problem structure is separated from the problem data, and the format moreover facilitate benchmarking of hotstart capability through sequences of changes....

  16. Usage Record Format Recommendation

    CERN Document Server

    Nilsen, J.K.; Muller-Pfeerkorn, R

    2013-01-01

    For resources to be shared, sites must be able to exchange basic accounting and usage data in a common format. This document describes a common format which enables the exchange of basic accounting and usage data from different resources. This record format is intended to facilitate the sharing of usage information, particularly in the area of the accounting of jobs, computing, memory, storage and cloud usage but with a structure that allows an easy extension to other resources. This document describes the Usage Record components both in natural language form and annotated XML. This document does not address how these records should be used, nor does it attempt to dictate the format in which the accounting records are stored. Instead, it denes a common exchange format. Furthermore, nothing is said regarding the communication mechanisms employed to exchange the records, i.e. transport layer, framing, authentication, integrity, etc.

  17. Challenges in Planet Formation

    CERN Document Server

    Morbidelli, Alessandro

    2016-01-01

    Over the past two decades, large strides have been made in the field of planet formation. Yet fundamental questions remain. Here we review our state of understanding of five fundamental bottlenecks in planet formation. These are: 1) the structure and evolution of protoplanetary disks; 2) the growth of the first planetesimals; 3) orbital migration driven by interactions between proto-planets and gaseous disk; 4) the origin of the Solar System's orbital architecture; and 5) the relationship between observed super-Earths and our own terrestrial planets. Given our lack of understanding of these issues, even the most successful formation models remain on shaky ground.

  18. Methemoglobin formation by paraquat.

    Directory of Open Access Journals (Sweden)

    Watanabe,Shinsaku

    1982-12-01

    Full Text Available Paraquat is a broad spectrum herbicide known to be highly lethal to man and animals. Its toxicity is characterized by acute lung injury. Paraquat produces such toxic effects through the generation of the superoxide anion according to one proposed mechanism. The present experiment, methemoglobin formation was demonstrated after incubation of oxyhemoglobin with paraquat. The generation of the superoxide anion through the interaction of oxyhemoglobin with paraquat was suggested by chemiluminescence of luminol. Superoxide dismutase (SOD and catalare inhibited methemoglobin formation. The generation of the superoxide anion is discussed in regard to methemoglobin formation by paraquat.

  19. Manuel UNIMARC format bibliographique

    CERN Document Server

    2007-01-01

    This manual is the French translation of the second edition of UNIMARC Manual: bibliographic format published in English in 1994 and completed by 5 updates published from 1996 to 2005. This 5th French edition is composite. It reproduces identically a part of the 4th edition published in 2002 and, for the fields of the format modified in the Update 5, it offers a new more structured presentation. This is a handbook dedicated to French-speaking users of the UNIMARC format for bibliographic descriptions.

  20. Mathematical Model of Forecasting the Formation of Sinkhole Using Salustowicz's Theory / Model Matematyczny Prognozowania Zapadlisk Przy Wykorzystaniu Teorii Sklepienia Ciśnień Sałustowicza

    Science.gov (United States)

    Strzałkowski, Piotr

    2015-03-01

    In area affected by old, shallow extraction in some cases sinkholes are formed, causing security issues in urbanized areas. Problem of working out deterministic forecast of this threat seems to be important and up-to-date. Mathematical model presented in this work let us predict the possibility of sinkhole formation. That prediction is essential for analyzing possibility of investments in such areas. Basing on presented work, it is also possible to determine dimensions of sinkhole. Considerations are based on known from literature Sałustowicz's theory, which is utilises Huber's solution of equation describing the stress state around elliptic void made in flat plate Początki eksploatacji górniczej na Górnym Śląsku sięgają XVIII stulecia. Dawna eksploatacja prowadzona na głębokościach nie przekraczających 80 m, do dziś generuje zagrożenia bezpieczeństwa powszechnego z uwagi na możliwość wystąpienia zapadlisk. Jak to wynika z pracy (Chudek i in., 2013), obszary pod którymi prowadzono w minionych latach płytką eksploatację zajmują znaczną powierzchnię śląskich miast, które w dalszym ciągu się rozbudowują. Dlatego problem występowania zapadlisk należy w dalszym ciągu uznać za ważny i aktualny. Duża liczba zapadlisk, ze zrozumiałych względów, jest wynikiem utraty stateczności płytkich wyrobisk korytarzowych. Istniejące metody prognozowania zapadlisk pozwalają głównie określać prawdopodobieństwo wystąpienia zapadliska. Jeśli wartość prawdopodobieństwa wystąpienia zapadliska jest większa od 0, wówczas należy się liczyć z zagrożeniem bezpieczeństwa terenu i co istotniejsze ludności. Taki sposób prognozowania wystąpienia zapadlisk nie daje jednoznacznej odpowiedzi na pytanie, czy teren objęty analizą jest rzeczywiście zagrożony. Dlatego istotnym jest stworzenie możliwości deterministycznego prognozowania tego typu deformacji. W tym kierunku zmierza propozycja autora pracy, w której wykorzystano teori

  1. Formation of planetary systems

    Science.gov (United States)

    Lin, Douglas N. C.

    The discovery of extrasolar planets and the determination of their orbital properties have provided golden opportunities for new advancements in the quest to understand the origin and evolution of planets and planetary systems. While their bizarre variety presents a challenge for the existing theories, their ubiquity suggests that planetary formation is a robust process. Combining data obtained from solar system exploration, star formation studies and the searches for extra solar planets, we address some outstanding issues concerning critical processes of grain condensation, planetesimal coagulation, and gas accretion. Some implications of these investigations are: 1) the about of heavy elements available for planetary formation in protostellar disks is retained at a similar level as that empirically inferred for the primordial solar nebula, through self regulated processes and 2) the critical stages of planet formation, from grain condensation, planetesimal coagulation, to gas accretion, proceed on the timescale of a few million years.

  2. Notes on Star Formation

    CERN Document Server

    Krumholz, Mark R

    2015-01-01

    This book provides an introduction to the field of star formation at a level suitable for graduate students or advanced undergraduates in astronomy or physics. The structure of the book is as follows. The first two chapters begin with a discussion of observational techniques, and the basic phenomenology they reveal. The goal is to familiarize students with the basic techniques that will be used throughout, and to provide a common vocabulary for the rest of the book. The next five chapters provide a similar review of the basic physical processes that are important for star formation. Again, the goal is to provide a basis for what follows. The remaining chapters discuss star formation over a variety of scales, starting with the galactic scale and working down to the scales of individual stars and their disks. The book concludes with a brief discussion of the clearing of disks and the transition to planet formation. The book includes five problem sets, complete with solutions.

  3. Primordial Planet Formation

    CERN Document Server

    Schild, Rudolph E

    2010-01-01

    Recent spacecraft observations exploring solar system properties impact standard paradigms of the formation of stars, planets and comets. We stress the unexpected cloud of microscopic dust resulting from the DEEP IMPACT mission, and the existence of molten nodules in STARDUST samples. And the theory of star formation does not explain the common occurrence of binary and multiple star systems in the standard gas fragmentation scenario. No current theory of planet formation can explain the iron core of the earth, under oceans of water. These difficulties are avoided in a scenario where the planet mass objects form primordially and are today the baryonic dark matter. They have been detected in quasar microlensing and anomalous quasar radio brightening bursts. The primordial planets often concentrate together to form a star, with residual matter seen in pre-stellar accretion discs around the youngest stars. These primordial planet mass bodies were formed of hydrogen-helium, aggregated in dense clumps of a trillion...

  4. Solar System formation

    CERN Document Server

    Crida, A

    2009-01-01

    In this review, three major changes in our understanding of the early history of the Solar System are presented. 1) Early differentiation: A few recent results support the idea that protoplanet formation and differentiation occurred partly simultaneously than CAI formation. First, some iron meteorites, eucrites, and angrites older than the chondrules or even than the CAI have been found. Second, iron meteorites could be debris of early disrupted differentiated planetesimals, scattered from the terrestrial planet region to the Main Belt. Finally, chondrules contain fragments of planetesimal material. 2) Earth and Moon: An equilibration mechanism explains the identical Oxygen isotopic composition of the Earth and the Moon. In addition, it has been shown that the Earth and the Moon mantles have the same 182^W anomaly, in contrast to what was believed before. Consequently, the Moon forming impact should have occurred after the extinction of the 182Hf radioactivity, about 60 Myr after Solar System formation. This ...

  5. Meningococcal biofilm formation

    DEFF Research Database (Denmark)

    Lappann, M.; Haagensen, Janus Anders Juul; Claus, H.;

    2006-01-01

    We show that in a standardized in vitro flow system unencapsulated variants of genetically diverse lineages of Neisseria meningitidis formed biofilms, that could be maintained for more than 96 h. Biofilm cells were resistant to penicillin, but not to rifampin or ciprofloxacin. For some strains......, microcolony formation within biofilms was observed. Microcolony formation in strain MC58 depended on a functional copy of the pilE gene encoding the pilus subunit pilin, and was associated with twitching of cells. Nevertheless, unpiliated pilE mutants formed biofilms showing that attachment and accumulation......X alleles was identified among genetically diverse meningococcal strains. PilX alleles differed in their propensity to support autoaggregation of cells in suspension, but not in their ability to support microcolony formation within biofilms in the continuous flow system....

  6. Densities and Kinematic Viscosities for the Systems Benzene + Methyl Formate, Benzene + Ethyl Formate, Benzene + Propyl Formate, and Benzene + Butyl Formate

    DEFF Research Database (Denmark)

    Emmerling, Uwe; Rasmussen, Peter

    1998-01-01

    Densities and kinematic viscosities have been measured for the system benzene + methyl formate at 20°C and for the systems benzene + ethyl formate, benzene + propyl formate, and benzene + butyl formate from 20°C to 50°C. The results for the system benzene + methyl formate have been correlated using...... a Redlich-Kister type of expression with temperature-independent parameters and the data for the systems benzene + ethyl formate, benzene + propyl formate, and benzene + butyl formate with temperature-dependent parameters. The viscosities have furthermore been compared to values predicted by means of the GC...

  7. The formation of stars

    CERN Document Server

    Stahler, Steven W

    2008-01-01

    This book is a comprehensive treatment of star formation, one of the most active fields of modern astronomy. The reader is guided through the subject in a logically compelling manner. Starting from a general description of stars and interstellar clouds, the authors delineate the earliest phases of stellar evolution. They discuss formation activity not only in the Milky Way, but also in other galaxies, both now and in the remote past. Theory and observation are thoroughly integrated, with the aid of numerous figures and images. In summary, this volume is an invaluable resource, both as a text f

  8. Tea aroma formation

    Directory of Open Access Journals (Sweden)

    Chi-Tang Ho

    2015-03-01

    Full Text Available Besides water, tea is one of the most popular beverages around the world. The chemical ingredients and biological activities of tea have been summarized recently. The current review summarizes tea aroma compounds and their formation in green, black, and oolong tea. The flavor of tea can be divided into two categories: taste (non-volatile compounds and aroma (volatile compounds. All of these aroma molecules are generated from carotenoids, lipids, glycosides, etc. precursors, and also from Maillard reaction. In the current review, we focus on the formation mechanism of main aromas during the tea manufacturing process.

  9. Formats and data storage

    International Nuclear Information System (INIS)

    The currently used ENDF-6 format has a number of shortcomings that originate from the punch-card legacy. Some, such as redundancy, counting lines, too short MAT number and too many options could be resolved within the current format. The more critical issues, such as rigidity to extensions, limited accuracy due to fixed number of digits, difficulty of reading by humans, lack of native software support, and lack of integration with EXFOR and ENSDF libraries, would require such considerable efforts that migration to a new and modern format, offering additional advantages, is a more attractive option. Actually, such an option is even more justified by the existence of the well advanced General Nuclear Data (GND) format being developed by LLNL. This XML based framework is easily extensible, its numerical precision is not fixed, it is easier to edit, can store additional information (e.g. renormalized experimental data used in the evaluation), allows for storing various versions side by side (e.g. reconstructed data, group-wise data, alternative evaluations), it may include hyperlinks to documentation or another set of data (e.g. covariances). Two additional advantages are the possibility of using native Python support software and already available conversion (in both directions) to the binary HDF5 format which allows to organize, store, access, analyze, share, and preserve data huge in both size and complexity. The GND format comes with the processing software FUDGE, whose class structure mirrors the GND format. It provides for arbitrary alteration of the data, energy deposition/kermas, data checking, translation to different format (ENDF-6, HDF5, ENDL), grouping, resonance reconstruction, visualization and sampling from covariances. It is deemed advantageous to the Nuclear Data community to adopt this new system and develop interfaces to the currently used processing codes and retrieval systems to take full advantage of the evolving technology. Such modernization is

  10. Sensitivity Data File Formats

    Energy Technology Data Exchange (ETDEWEB)

    Rearden, Bradley T. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2016-04-01

    The format of the TSUNAMI-A sensitivity data file produced by SAMS for cases with deterministic transport solutions is given in Table 6.3.A.1. The occurrence of each entry in the data file is followed by an identification of the data contained on each line of the file and the FORTRAN edit descriptor denoting the format of each line. A brief description of each line is also presented. A sample of the TSUNAMI-A data file for the Flattop-25 sample problem is provided in Figure 6.3.A.1. Here, only two profiles out of the 130 computed are shown.

  11. Terrestrial planet formation

    OpenAIRE

    Righter, K.; D. P. O’Brien

    2011-01-01

    Advances in our understanding of terrestrial planet formation have come from a multidisciplinary approach. Studies of the ages and compositions of primitive meteorites with compositions similar to the Sun have helped to constrain the nature of the building blocks of planets. This information helps to guide numerical models for the three stages of planet formation from dust to planetesimals (∼106 y), followed by planetesimals to embryos (lunar to Mars-sized objects; few × 106 y), and finally e...

  12. Kepler Planet Formation

    Science.gov (United States)

    Lissauer, Jack J.

    2015-01-01

    Kepler has vastly increased our knowledge of planets and planetary systems located close to stars. The new data shows surprising results for planetary abundances, planetary spacings and the distribution of planets on a mass-radius diagram. The implications of these results for theories of planet formation will be discussed.

  13. Gravitational Structure Formation

    OpenAIRE

    Labini, Francesco Sylos; Baertschiger, Thierry

    2005-01-01

    We discuss the formation of the first structures in gravitational N-body simulations. The role of two-body interaction is found to be a crucial element and an analogy with the dynamics of the Coulomb lattice, well-studied in solid state physics, is discussed.

  14. Reference Citation Format

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    <正>The format for citations in text and for bibliographic references follows the Publication Manual of the American Psychological Association(5thEd.,2001)and GB/T 7714-2005.The citation of printed word should be ordered in number as it appears in the text of the submitted

  15. Airship formation control

    OpenAIRE

    Bicho, E.; Moreira, André; Diegues, Sérgio; Carvalheira, Manuel Pereira; Monteiro, Sérgio

    2006-01-01

    This paper addresses the problem underlying the control and coordination of multiple autonomous airships that must travel maintaining a desired geometric formation and simultaneously avoid collisions with moving or stationary obstacles. The control architecture is based on the attractor dynamics approach to behaviour generation. The airship physical model is presented and the mathematical background for the control architecture is explained. Simulations (with perturbations) ...

  16. Syntactic Formats for Free

    DEFF Research Database (Denmark)

    Klin, Bartek; Sobocinski, Pawel

    2003-01-01

    A framework of Plotkin and Turi’s, originally aimed at providing an abstract notion of bi-simulation, is modified to cover other operational equivalences and preorders. Combined with bi-algebraic methods, it yields a technique for the derivation of syntactic formats for transition system specific...

  17. Generic file format

    Science.gov (United States)

    Felgate, Nick

    2002-11-01

    The Generic File Format (GFF) is a file format developed within the UK ASW community for the interchange and storage of underwater sonar data. Originally developed for the interchange of time-series data between analysis systems, it has been extended to provide for storage of processed acoustic data (e.g., power and DEMON spectrum, lofargram grey-scale), nonacoustic data (e.g., own-ship dynamics, sensor configuration) and event data (e.g., tracker output, sonar intercepts). The format employs the chunk concept, as used in the WAV and AIFF file formats, to provide extendability (including local variants) while providing a measure of backward compatability. However, the basic concept has been adapted to allow for the mixing in the one file of multiple channels of different sample-rates and data-types through the inclusion of a data frame concept and multiple data blocks. Chunk cross-referencing has been employed to ensure data consistency. A provision is made in the header of the file to store details of the sensor and processing for the data (e.g., the number of hydrophones, beam direction, FFT size) so that an analysis system does not need to know about the sensor or other system from which the data originated.

  18. Symbol Formation Reconsidered

    DEFF Research Database (Denmark)

    Wagoner, Brady

    2013-01-01

    Werner and Kaplan’s Symbol formation was published 50 years ago but its insights have yet to be adequately explored by psychology and other social sciences. This special issue aims to revisit this seminal work in search of concepts to work on key issues facing us today. This introductory article...... them vis-à-vis other research at Clark and in American psychology more generally. The second two articles analyse Werner and Kaplan’s notions of ‘distancing’ and ‘physiognomic metaphor’, showing their roots in naturphilosophie and comparing them with contemporary theories. The last four articles apply...... the organismic-developmental approach to fields only touched in Symbol formation, such as magical practices, social structures, pictures and gesture....

  19. Simulating Cosmic Structure Formation

    CERN Document Server

    Weinberg, D H; Hernquist, L E; Weinberg, David H.; Katz, Neal; Hernquist, Lars

    1997-01-01

    We describe cosmological simulation techniques and their application to studies of cosmic structure formation, with particular attention to recent hydrodynamic simulations of structure in the high redshift universe. Collisionless N-body simulations with Gaussian initial conditions produce a pattern of sheets, filaments, tunnels, and voids that resembles the observed large scale galaxy distribution. Simulations that incorporate gas dynamics and dissipation form dense clumps of cold gas with sizes and masses similar to the luminous parts of galaxies. Models based on inflation and cold dark matter predict a healthy population of high redshift galaxies, including systems with star formation rates of 20 M_{\\sun}/year at z=6. At z~3, most of the baryons in these models reside in the low density intergalactic medium, which produces fluctuating Lyman-alpha absorption in the spectra of background quasars. The physical description of this ``Lyman-alpha forest'' is particularly simple if the absorption spectrum is viewe...

  20. Emptiness Formation Probability

    Science.gov (United States)

    Crawford, Nicholas; Ng, Stephen; Starr, Shannon

    2016-08-01

    We present rigorous upper and lower bounds on the emptiness formation probability for the ground state of a spin-1/2 Heisenberg XXZ quantum spin system. For a d-dimensional system we find a rate of decay of the order {exp(-c L^{d+1})} where L is the sidelength of the box in which we ask for the emptiness formation event to occur. In the {d=1} case this confirms previous predictions made in the integrable systems community, though our bounds do not achieve the precision predicted by Bethe ansatz calculations. On the other hand, our bounds in the case {d ≥ 2} are new. The main tools we use are reflection positivity and a rigorous path integral expansion, which is a variation on those previously introduced by Toth, Aizenman-Nachtergaele and Ueltschi.

  1. Plasma formation in TBR

    International Nuclear Information System (INIS)

    In this work are presented and discussed results of the formation and equilibrium of the plasma current in TBR, a small tokamak, designed and contructed at the Instituto de Fisica of Universidade de Sao Paulo. The measured breakdown curves for H2, A and He are compared with the predictions of a simple model with reasonable agreement. The influence of stray magnetic fields in the plasma formation is investigated and conditions are chosen to facilitate the breakdown. The time profile of loop voltage and plasma current for shots with plasma equilibrium are shown. A comparison is made between experimental results and analytical-numerical model for tokamaks discharges with ohmic heating. Reasonable agreement is obtained when Z, effective atomic number, is assumed as a parameter. (Author)

  2. Induced galaxy formation

    CERN Document Server

    Dokuchaev, V; Rubin, S; Dokuchaev, Vyacheslav; Eroshenko, Yury; Rubin, Sergei

    2004-01-01

    We describe the model of protogalaxy formation around the cluster of primordial black holes with a minimum extension of standard cosmological model. Namely, it is supposed, that a mass fraction of the universe ~10^-3 is composed of the compact clusters of primordial (relict) black holes produced during the phase transitions in the early universe. These clusters are the centers of the dark matter (DM) condensations. As a result the protogalaxies with a mass 2x10^8Msun form at the redshift z=15. These induced protogalaxies contain the central black holes of mass ~10^5Msun and look like the dwarf spheroidal galaxies with a central density spike. Subsequent merging of the induced protogalaxies and ordinary DM haloes leads to the standard scenario of the large scale structure formation. Black holes merging gives the nowadays supermassive black holes and reproduces the observed correlations between their masses and velocity dispersions in the bulges.

  3. Formation of multiple networks

    DEFF Research Database (Denmark)

    Magnani, Matteo; Rossi, Luca

    2013-01-01

    While most research in Social Network Analysis has focused on single networks, the availability of complex on-line data about individuals and their mutual heterogenous connections has recently determined a renewed interest in multi-layer network analysis. To the best of our knowledge, in this paper...... we introduce the first network formation model for multiple networks. Network formation models are among the most popular tools in traditional network studies, because of both their practical and theoretical impact. However, existing models are not sufficient to describe the generation of multiple...... networks. Our model, motivated by an empirical analysis of real multi-layered network data, is a conservative extension of single-network models and emphasizes the additional level of complexity that we experience when we move from a single- to a more complete and realistic multi-network context....

  4. Modeling river delta formation

    OpenAIRE

    Seybold, Hansjörg; Andrade, José S.; Herrmann, Hans J.

    2007-01-01

    A model to simulate the time evolution of river delta formation process is presented. It is based on the continuity equation for water and sediment flow and a phenomenological sedimentation/erosion law. Different delta types are reproduced by using different parameters and erosion rules. The structures of the calculated patterns are analyzed in space and time and compared with real data patterns. Furthermore, our model is capable of simulating the rich dynamics related to the switching of the...

  5. Frost formation with salt

    OpenAIRE

    Guadarrama-Cetina, J.; Mongruel, A. (Anne); González-Viñas, W.; Beysens, D.A. (Daniel A.)

    2015-01-01

    The formation of frost in presence of salt (NaCl) crystal is experimentally investigated on a hydrophobic surface. It presents several remarkable features due to the interplay of salty-water saturation pressure evolution, initially lower than the saturation pressure of ice and water, and the percolating propagation of ice dendrites from defects throughout the supercooled water droplet pattern. In particular, it is remarkable that nucleation of supercooled water and/or ice is prevented around ...

  6. Formate-assisted pyrolysis

    Science.gov (United States)

    DeSisto, William Joseph; Wheeler, Marshall Clayton; van Heiningen, Adriaan R. P.

    2015-03-17

    The present invention provides, among other thing, methods for creating significantly deoxygenated bio-oils form biomass including the steps of providing a feedstock, associating the feedstock with an alkali formate to form a treated feedstock, dewatering the treated feedstock, heating the dewatered treated feedstock to form a vapor product, and condensing the vapor product to form a pyrolysis oil, wherein the pyrolysis oil contains less than 30% oxygen by weight.

  7. Reference Citation Format

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    <正>The format for citations in text and for bibliographic references follows the Publication Manual of the American Psychological Association(5thEd.,2001)and GB/T 7714-2005.The citation of printed word should be ordered in number as it appears in the text of the submitted article.For journal article1 Goodrum,A.A.,McCain,K.W.,&Lawrence,S.,et al.Scholarly publishing in the Internet

  8. Reference Citation Format

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    <正>The format for citations in text and for bibliographic references follows the Publication Manual of the American Psychological Association(5thEd.,2001)and GB/T 7714-2005.The citation of printed word should be ordered in number as it appears in the text of the submitted article.For journal article1 Goodrum,A.A.,McCain,K.W.,&Lawrence,S.,et al.Scholarly publishing in the Internet age:

  9. Reference Citation Format

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    <正>The format for citations in text and for bibliographic references follows the Publication Manual of the American Psychological Association(5thEd.,2001)and GB/T 7714-2005.The citation of printed word should be ordered in number as it appears in the text of the submitted article.For journal article1 Goodrum,A.A.,McCain,K.W.,&Lawrence,S.,et al.Scholarly publishing in the Internet

  10. Reference Citation Format

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    <正>The format for citations in text and for bibliographic references follows the Publication Manual of the American Psychological Association(5thEd.,2001)and GB/T 7714-2005.The citation of printed word should be ordered in number as it appears in the text of the submitted article.For journal article1 Goodrum,A.A.,McCain,K.W.,&Lawrence,S.,et al.Scholarly publishing in the Internet age:

  11. Formation of transient lamellipodia.

    Directory of Open Access Journals (Sweden)

    Juliane Zimmermann

    Full Text Available Cell motility driven by actin polymerization is pivotal to the development and survival of organisms and individual cells. Motile cells plated on flat substrates form membrane protrusions called lamellipodia. The protrusions repeatedly appear and retract in all directions. If a lamellipodium is stabilized and lasts for some time, it can take over the lead and determine the direction of cell motion. Protrusions traveling along the cell perimeter have also been observed. Their initiation is in some situations the effect of the dynamics of the pathway linking plasma membrane receptors to actin filament nucleation, e.g. in chemotaxis. However, lamellipodia are also formed in many cells incessantly during motion with a constant state of the signaling pathways upstream from nucleation promoting factors (NPFs, or spontaneously in resting cells. These observations strongly suggest protrusion formation can also be a consequence of the dynamics downstream from NPFs, with signaling setting the dynamic regime but not initiating the formation of individual protrusions. A quantitative mechanism for this kind of lamellipodium dynamics has not been suggested yet. Here, we present a model exhibiting excitable actin network dynamics. Individual lamellipodia form due to random supercritical filament nucleation events amplified by autocatalytic branching. They last for about 30 seconds to many minutes and are terminated by filament bundling, severing and capping. We show the relevance of the model mechanism for experimentally observed protrusion dynamics by reproducing in very good approximation the repetitive protrusion formation measured by Burnette et al. with respect to the velocities of leading edge protrusion and retrograde flow, oscillation amplitudes, periods and shape, as well as the phase relation between protrusion and retrograde flow. Our modeling results agree with the mechanism of actin bundle formation during lamellipodium retraction suggested by

  12. Egg Formation in Lepidoptera

    OpenAIRE

    William H. Telfer

    2009-01-01

    Reproductive biology in the Twentieth Century produced comprehensive descriptions of the mechanisms of egg formation in most of the major orders of insects. While many general principles of ovarian development and physiology emerged, every order turned out to have a set of its own special motifs. Discovery of the lepidopteran motifs is summarized in this essay. The emphasis is on developmental mechanisms, beginning with the early growth and differentiation of female germ cells and ending, aft...

  13. Isothermal Martensite Formation

    DEFF Research Database (Denmark)

    Villa, Matteo

    are chosen to investigate time dependent martensite formation. Among them, a Fe-11wt%Ni-0.6wt%C model alloy and Fe-1.6wt%Cr-1wt%C (AISI 52100), Fe-17wt%Cr-7wt%Ni (AISI 631) and Fe-16wt%Cr-5wt%Ni (AISI 630) commercial steels. The investigation was performed with in situ magnetometry, dilatometry, synchrotron...

  14. Galaxy Formation and Evolution

    Science.gov (United States)

    Nagamine, Kentaro; Reddy, Naveen; Daddi, Emanuele; Sargent, Mark T.

    2016-07-01

    In this chapter, we discuss the current status of observational and computational studies on galaxy formation and evolution. In particular, a joint analysis of star-formation rates (SFRs), stellar masses, and metallicities of galaxies throughout cosmic time can shed light on the processes by which galaxies build up their stellar mass and enrich the environment with heavy elements. Comparison of such observations and the results of numerical simulations can give us insights on the physical importance of various feedback effects by supernovae and active galactic nuclei. In Sect. 1, we first discuss the primary methods used to deduce the SFRs, stellar masses, and (primarily) gas-phase metallicities in high-redshift galaxies. Then, we show how these quantities are related to each other and evolve with time. In Sect. 2, we further examine the distribution of SFRs in galaxies following the `Main Sequence' paradigm. We show how the so-called `starbursts' display higher specific SFRs and SF efficiencies by an order of magnitude. We use this to devise a simple description of the evolution of the star-forming galaxy population since z ˜3 that can successfully reproduce some of the observed statistics in the infrared (IR) wavelength. We also discuss the properties of molecular gas. In Sect. 3, we highlight some of the recent studies of high-redshift galaxy formation using cosmological hydrodynamic simulations. We discuss the physical properties of simulated galaxies such as luminosity function and escape fraction of ionizing photons, which are important statistics for reionization of the Universe. In particular the escape fraction of ionizing photons has large uncertainties, and studying gamma-ray bursts (which is the main topic of this conference) can also set observational constraints on this uncertain physical parameter as well as cosmic star formation rate density.

  15. Reference Citation Format

    Institute of Scientific and Technical Information of China (English)

    2014-01-01

    <正>The format for citations in text and for bibliographic references follows GB/T 7714—2005.The citation should be ordered in number as it appears in the text of the submitted article.For journal article Sun,Y.,Li,B.,&Qu,J.F.Design and implementation of library intelligent IM reference robot.New Technology of Library and Information Service(in Chinese),

  16. Reference Citation Format

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    <正>The format for citations in text and for bibliographic references follows GB/T 7714—2005.The citation should be ordered in number as it appears in the text of the submitted article.For journal article Sun,Y.,Li,B.,&Qu,J.F.Design and implementation of library intelligent IM reference robot.New Technology of Library and Information Service(in Chinese),2011,205:88–92.

  17. Unemployment and Household formation

    OpenAIRE

    Ebrahim, Amina; Woolard, Ingrid; Leibbrandt, Murray

    2013-01-01

    In comparison to other continents, Africa has received little scholarly attention with regard to household composition. Household composition is endogenous to a variety of welfare issues and little is understood about the determinants of this composition. Understanding the household composition and formation decision may improve our understanding of how the unemployed gain access to resources and how household composition could provide a safety net to the unemployed. However, increasingly, mo...

  18. Cyst formation by Methanosarcina

    Energy Technology Data Exchange (ETDEWEB)

    Zhilina, T.N.; Zavarzin, G.A.

    1979-05-01

    The morphology of a coccoid, methane producing bacterium growing on acetate was studied. The organism is capable of forming morphologically differentiated cells, microcysts, whose structure resembles that of bacterial surviving cells. The organism forms peculiar macrocysts in the enrichment culture. In its other characteristics, the organism is similar to Methanococcus mazei. However, it classified as Methanosarcina, biotype 3, due to the characteristic formation of multicellular pseudococci.

  19. Terrestrial planet formation.

    Science.gov (United States)

    Righter, K; O'Brien, D P

    2011-11-29

    Advances in our understanding of terrestrial planet formation have come from a multidisciplinary approach. Studies of the ages and compositions of primitive meteorites with compositions similar to the Sun have helped to constrain the nature of the building blocks of planets. This information helps to guide numerical models for the three stages of planet formation from dust to planetesimals (~10(6) y), followed by planetesimals to embryos (lunar to Mars-sized objects; few 10(6) y), and finally embryos to planets (10(7)-10(8) y). Defining the role of turbulence in the early nebula is a key to understanding the growth of solids larger than meter size. The initiation of runaway growth of embryos from planetesimals ultimately leads to the growth of large terrestrial planets via large impacts. Dynamical models can produce inner Solar System configurations that closely resemble our Solar System, especially when the orbital effects of large planets (Jupiter and Saturn) and damping mechanisms, such as gas drag, are included. Experimental studies of terrestrial planet interiors provide additional constraints on the conditions of differentiation and, therefore, origin. A more complete understanding of terrestrial planet formation might be possible via a combination of chemical and physical modeling, as well as obtaining samples and new geophysical data from other planets (Venus, Mars, or Mercury) and asteroids. PMID:21709256

  20. The Star Formation Camera

    CERN Document Server

    Scowen, Paul A; Beasley, Matthew; Calzetti, Daniela; Desch, Steven; Fullerton, Alex; Gallagher, John; Lisman, Doug; Macenka, Steve; Malhotra, Sangeeta; McCaughrean, Mark; Nikzad, Shouleh; O'Connell, Robert; Oey, Sally; Padgett, Deborah; Rhoads, James; Roberge, Aki; Siegmund, Oswald; Shaklan, Stuart; Smith, Nathan; Stern, Daniel; Tumlinson, Jason; Windhorst, Rogier; Woodruff, Robert

    2009-01-01

    The Star Formation Camera (SFC) is a wide-field (~15'x19, >280 arcmin^2), high-resolution (18x18 mas pixels) UV/optical dichroic camera designed for the Theia 4-m space-borne space telescope concept. SFC will deliver diffraction-limited images at lambda > 300 nm in both a blue (190-517nm) and a red (517-1075nm) channel simultaneously. Our aim is to conduct a comprehensive and systematic study of the astrophysical processes and environments relevant for the births and life cycles of stars and their planetary systems, and to investigate and understand the range of environments, feedback mechanisms, and other factors that most affect the outcome of the star and planet formation process. This program addresses the origins and evolution of stars, galaxies, and cosmic structure and has direct relevance for the formation and survival of planetary systems like our Solar System and planets like Earth. We present the design and performance specifications resulting from the implementation study of the camera, conducted ...

  1. Formation of Lunar Swirls

    CERN Document Server

    Bamford, R A; Cruz, F; Kellett, B J; Fonseca, R A; Silva, L O; Trines, R M G M; Halekas, J S; Kramer, G; Harnett, E; Cairns, R A; Bingham, R

    2015-01-01

    In this paper we show a plausible mechanism that could lead to the formation of the Dark Lanes in Lunar Swirls, and the electromagnetic shielding of the lunar surface that results in the preservation of the white colour of the lunar regolith. We present the results of a fully self-consistent 2 and 3 dimensional particle-in-cell simulations of mini-magnetospheres that form above the lunar surface and show that they are consistent with the formation of `lunar swirls' such as the archetypal formation Reiner Gamma. The simulations show how the microphysics of the deflection/shielding of plasma operates from a kinetic-scale cavity, and show that this interaction leads to a footprint with sharp features that could be the mechanism behind the generation of `dark lanes'. The physics of mini-magnetospheres is described and shown to be controlled by space-charge fields arising due to the magnetized electrons and unmagnetized ions. A comparison between model and observation is shown for a number of key plasma parameters...

  2. Bouyei word formation

    Directory of Open Access Journals (Sweden)

    Attasith Boonsawasd

    2012-12-01

    Full Text Available The Bouyei language is divided into three vernaculars, the southern vernacular, the central vernacular and the southwestern vernacular. This paper aims to describe the lexicology of the southern vernacular of the Bouyei language focusing on word formation process. Bouyei words are formed by affixing, compounding and reduplicating. First, the affixation consists of prefixing and suffixing. Infixing is not found in this language. Second, the compound is divided into the semantic and syntactic compound. Finally, the reduplication is divided into the simple and complex reduplication. The simple reduplication is normally used to emphasize the meaning of the root or to indicate plurality.

  3. Modeling river delta formation

    CERN Document Server

    Seybold, Hansjörg; Herrmann, Hans J

    2007-01-01

    A new model to simulate the time evolution of river delta formation process is presented. It is based on the continuity equation for water and sediment flow and a phenomenological sedimentation/ erosion law. Different delta types are reproduced using different parameters and erosion rules. The structures of the calculated patterns are analyzed in space and time and compared with real data patterns. Furthermore our model is capable to simulate the rich dynamics related to the switching of the mouth of the river delta. The simulation results are then compared with geological records for the Mississippi river.

  4. Modeling river delta formation.

    Science.gov (United States)

    Seybold, Hansjörg; Andrade, José S; Herrmann, Hans J

    2007-10-23

    A model to simulate the time evolution of river delta formation process is presented. It is based on the continuity equation for water and sediment flow and a phenomenological sedimentation/erosion law. Different delta types are reproduced by using different parameters and erosion rules. The structures of the calculated patterns are analyzed in space and time and compared with real data patterns. Furthermore, our model is capable of simulating the rich dynamics related to the switching of the mouth of the river delta. The simulation results are then compared with geological records for the Mississippi River. PMID:17940031

  5. Reference Citation Format

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    <正>The format for citations in text and for bibliographic references follows the Publication Manual of the American Psychological Association(5thEd.,2001)and GB/T 7714-2005.The citation of printed word should be ordered in number as it appears in the text of the submitted article.For journal article1 Goodrum,A.A.,McCain,K.W.,&Lawrence,S.,et al.Scholarly publishing in the Internet age:A citation analysis of computer science literature.Information Processing and Management,2001,37:661-675.2 Fernandez,M.,Kadiyska,Y.,&Suciu,D.,et al.SilkRoute:A framework for publishing

  6. Reference Citation Format

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    <正>The format for citations in text and for bibliographic references follows the Publication Manual of the American Psychological Association(5thEd.,2001)and GB/T 7714-2005.The citation of printed word should be ordered in number as it appears in the text of the submitted article.For journal article1 Goodrum,A.A.,McCain,K.W.,&Lawrence,S.,et al.Scholarly publishing in the Internet age:A citation analysis of computer science literature.Information Processing and Manage-

  7. Reference Citation Format

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    <正>The format for citations in text and for bibliographic references follows the Publication Manual of the American Psychological Association(5th Ed.,2001)and GB/T 7714-2005.The citation of printed word should be ordered in number as it appears in the text of the submitted article.For journal article1 Goodrum,A.A.,McCain,K.W.,&Lawrence,S.,et al.Scholarly publishing in the Internet age:A citation analysis of computer science literature.Information Processing and Management,2001,37:661-675.

  8. Reference Citation Format

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    <正>The format for citations in text and for bibliographic references follows the Publication Manual of the American Psychological Association(5thEd.,2001)and GB/T 7714-2005.The citation of printed word should be ordered in number as it appears in the text of the submitted article.For journal article1 Goodrum,A.A.,McCain,K.W.,&Lawrence,S.,et al.Scholarly publishing in the Internet age:A citation analysis of computer science literature.Information Processing and Management,2001,37:661-675.2 Fernandez.M

  9. Formation control of AAUSHIP

    DEFF Research Database (Denmark)

    Østergaard, Nick; Dam, Jeppe; Larsen, Jesper Abildgaard

    2015-01-01

    Many maritime mapping tasks are today carried out by large research ships, which are very costly to operate. As a way to overcome this, a number of small surveying vessels have been developed called AAUSHIP. In order to efficiently map the an area with such smaller vessels, it is important that s...... that several vessels are able to corporate on the task at hand. In this paper, the developed formation control strategy for the AAUSHIP series of vessels is presented, along with simulation results, which confirms, that the algorithm works as intended....

  10. The Star Formation Camera

    OpenAIRE

    Scowen, Paul A.; Jansen, Rolf; Beasley, Matthew; Calzetti, Daniela; Desch, Steven; Fullerton, Alex; Gallagher, John; Lisman, Doug; Macenka, Steve; Malhotra, Sangeeta; McCaughrean, Mark; Nikzad, Shouleh; O'Connell, Robert; Oey, Sally; Padgett, Deborah

    2009-01-01

    The Star Formation Camera (SFC) is a wide-field (~15'x19, >280 arcmin^2), high-resolution (18x18 mas pixels) UV/optical dichroic camera designed for the Theia 4-m space-borne space telescope concept. SFC will deliver diffraction-limited images at lambda > 300 nm in both a blue (190-517nm) and a red (517-1075nm) channel simultaneously. Our aim is to conduct a comprehensive and systematic study of the astrophysical processes and environments relevant for the births and life cycles of stars and ...

  11. Star Formation in Irregular Galaxies.

    Science.gov (United States)

    Hunter, Deidre; Wolff, Sidney

    1985-01-01

    Examines mechanisms of how stars are formed in irregular galaxies. Formation in giant irregular galaxies, formation in dwarf irregular galaxies, and comparisons with larger star-forming regions found in spiral galaxies are considered separately. (JN)

  12. Parametrising Star Formation Histories

    CERN Document Server

    Simha, Vimal; Conroy, Charlie; Dave, Romeel; Fardal, Mark; Katz, Neal; Oppenheimer, Benjamin D

    2014-01-01

    We examine the star formation histories (SFHs) of galaxies in smoothed particle hydrodynamics (SPH) simulations, compare them to parametric models that are commonly used in fitting observed galaxy spectral energy distributions, and examine the efficacy of these parametric models as practical tools for recovering the physical parameters of galaxies. The commonly used tau-model, with SFR ~ exp(-t/tau), provides a poor match to the SFH of our SPH galaxies, with a mismatch between early and late star formation that leads to systematic errors in predicting colours and stellar mass-to-light ratios. A one-parameter lin-exp model, with SFR ~ t*exp(-t/tau), is much more successful on average, but it fails to match the late-time behavior of the bluest, most actively star-forming galaxies and the passive, "red and dead" galaxies. We introduce a 4-parameter model, which transitions from lin-exp to a linear ramp after a transition time, which describes our simulated galaxies very well. We test the ability of these paramet...

  13. Formation of planetary systems

    International Nuclear Information System (INIS)

    It seemed appropriate to devote the 1980 School to the origin of the solar system and more particularly to the formation of planetary systems (dynamic accretion processes, small bodies, planetary rings, etc...) and to the physics and chemistry of planetary interiors, surface and atmospheres (physical and chemical constraints associated with their formation). This Summer School enabled both young researchers and hard-nosed scientists, gathered together in idyllic surroundings, to hold numerous discussions, to lay the foundations for future cooperation, to acquire an excellent basic understanding, and to make many useful contacts. This volume reflects the lectures and presentations that were delivered in this Summer School setting. It is aimed at both advanced students and research workers wishing to specialize in planetology. Every effort has been made to give an overview of the basic knowledge required in order to gain a better understanding of the origin of the solar system. Each article has been revised by one or two referees whom I would like to thank for their assistance. Between the end of the School in August 1980 and the publication of this volume in 1982, the Voyager probes have returned a wealth of useful information. Some preliminary results have been included for completeness

  14. The Planet Formation Imager

    Science.gov (United States)

    Kraus, S.; Buscher, D. F.; Monnier, J. D.; PFI Science, the; Technical Working Group

    2014-04-01

    Among the most fascinating and hotly-debated areas in contemporary astrophysics are the means by which planetary systems are assembled from the large rotating disks of gas and dust which attend a stellar birth. Although important work is being done both in theory and observation, a full understanding of the physics of planet formation can only be achieved by opening observational windows able to directly witness the process in action. The key requirement is then to probe planet-forming systems at the natural spatial scales over which material is being assembled. By definition, this is the so-called Hill Sphere which delineates the region of influence of a gravitating body within its surrounding environment. The Planet Formation Imager project has crystallized around this challenging goal: to deliver resolved images of Hill-Sphere-sized structures within candidate planet-hosting disks in the nearest star-forming regions. In this contribution we outline the primary science case of PFI and discuss how PFI could significantly advance our understanding of the architecture and potential habitability of planetary systems. We present radiation-hydrodynamics simulations from which we derive preliminary specifications that guide the design of the facility. Finally, we give an overview about the interferometric and non-interferometric technologies that we are investigating in order to meet the specifications.

  15. Thiol isomerases in thrombus formation

    OpenAIRE

    Furie, Bruce; Flaumenhaft, Robert

    2014-01-01

    Protein disulfide isomerase, ERp5 and ERp57, among perhaps other thiol isomerases, are important for the initiation of thrombus formation. Using the laser injury thrombosis model in mice to induce in vivo arterial thrombus formation, it was shown that thrombus formation is associated with PDI secretion by platelets, that inhibition of PDI blocked platelet thrombus formation and fibrin generation, and that endothelial cell activation leads to PDI secretion. Similar results using this and other...

  16. Designing for informed group formation

    DEFF Research Database (Denmark)

    Nicolajsen, Hanne Westh; Juel Jacobsen, Alice; Riis, Marianne

    2012-01-01

    A new design ―project preparation‖ preparing for the group formation in problem based project work is proposed and investigated. The main problem is to overcome group formation based on existing relations. The hypothesis is that theme development and group formation are somewhat counterproductive...

  17. Social Network Formation with Consent

    NARCIS (Netherlands)

    Gilles, R.P.; Sarangi, S.

    2004-01-01

    We investigate the equilibria of game theoretic models of network formation that are based on individual actions only.Our approach is grounded in three simple and realistic principles: (1) Link formation should be a binary process of consent.(2) Link formation should be costly.(3) The class of netwo

  18. Cosmological Structure Formation

    CERN Document Server

    Primack, Joel R

    2015-01-01

    LCDM is remarkably successful in predicting the cosmic microwave background and large-scale structure, and LCDM parameters have been determined with only mild tensions between different types of observations. Hydrodynamical simulations starting from cosmological initial conditions are increasingly able to capture the complex interactions between dark matter and baryonic matter in galaxy formation. Simulations with relatively low resolution now succeed in describing the overall galaxy population. For example, the EAGLE simulation in volumes up to 100 cubic Mpc reproduces the observed local galaxy mass function nearly as well as semi-analytic models. It once seemed that galaxies are pretty smooth, that they generally grow in size as they evolve, and that they are a combination of disks and spheroids. But recent HST observations combined with high-resolution hydrodynamic simulations are showing that most star-forming galaxies are very clumpy; that galaxies often undergo compaction which reduces their radius and ...

  19. Synapse formation and remodeling

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Synapses are specialized structures that mediate information flow between neurons and target cells,and thus are the basis for neuronal system to execute various functions,including learning and memory.There are around 1011 neurons in the human brain,with each neuron receiving thousands of synaptic inputs,either excitatory or inhibitory.A synapse is an asymmetric structure that is composed of pre-synaptic axon terminals,synaptic cleft,and postsynaptic compartments.Synapse formation involves a number of cell adhesion molecules,extracellular factors,and intracellular signaling or structural proteins.After the establishment of synaptic connections,synapses undergo structural or functional changes,known as synaptic plasticity which is believed to be regulated by neuronal activity and a variety of secreted factors.This review summarizes recent progress in the field of synapse development,with particular emphasis on the work carried out in China during the past 10 years(1999-2009).

  20. Dislocation Formation in Alloys

    Science.gov (United States)

    Minami, Akihiko; Onuki, Akira

    2006-05-01

    An interaction between dislocations and phase transitions is studied by a phase field model both in two and three dimensional systems. Our theory is a simple extension of the traditional linear elastic theory, and the elastic energy is a periodic function of local strains which is reflecting the periodicity of crystals. We find that the dislocations are spontaneously formed by quenching. Dislocations are formed from the interface of binary alloys, and slips are preferentially gliding into the soft metals. In three dimensional systems, formation of dislocations under applied strain is studied in two phase state. We find that the dislocation loops are created from the surface of hard metals. We also studied the phase separation above the coexisting temperature which is called as the Cottrell atmosphere. Clouds of metals cannot catch up with the motion of dislocations at highly strained state.

  1. Determinants for gallstone formation

    DEFF Research Database (Denmark)

    Shabanzadeh, Daniel Monsted; Sorensen, Lars Tue; Jørgensen, Torben

    2016-01-01

    . Gallstone incidence was assessed through repeated ultrasound examinations. Body mass index (BMI), blood pressure, self-rated health, lifestyle variables, blood lipids, and use of female sex hormones were measured at the baseline examination. Statistical analyses included logistic regression. Based...... on a prospective protocol, a systematic review of the literature was performed identifying all articles dealing with determinants of incident gallstones. Meta-analyses of comparable determinants were performed through fixed effect models. Results: Participants with no gallstones at baseline and with at least one...... associations were found for blood pressure, smoking, alcohol consumption, HDL cholesterol, or triglycerides in meta-analyses. Conclusions: Age, female sex, BMI, non-HDL cholesterol, and polyps are independent determinants for gallstone formation. Incident gallstones and the metabolic syndrome share common risk...

  2. Physics of amniote formation.

    Science.gov (United States)

    Fleury, Vincent; Murukutla, Ameya Vaishnavi; Chevalier, Nicolas R; Gallois, Benjamin; Capellazzi-Resta, Marina; Picquet, Pierre; Peaucelle, Alexis

    2016-08-01

    We present a detailed study of the formation of the amniotic sac in the avian embryo, and a comparison with the crocodile amniotic sac. We show that the amniotic sac forms at a circular line of stiffness contrast, separating rings of cell domains. Cells align at this boundary, and this in turn orients and concentrates the tension forces. The tissue fold which forms the amniotic sac is locked exactly along this line due to the colocalization of the stiffness contrast and of the tensile force. In addition, the tensile force plays a regenerative role when the amniotic sac is cut. The fold forming the ventral side of the embryo displays the same characteristics. This work shows that amniote embryogenesis consists of a cascade of buckling events taking place at the boundaries between regions of differing mechanical properties. Hence, amniote embryogenesis relies on a simple and robust biomechanical scheme used repeatedly, and selected ancestrally. PMID:27627351

  3. Reference Citation Format

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    <正>The format for citations in text and for bibliographic references follows the Publication Manual of the American Psychological Association(5thEd.,2001)and GB/T 7714-2005.The citation of printed word should be ordered in number as it appears in the text of the submitted article.For journal article1 Goodrum,A.A.,McCain,K.W.,&Lawrence,S.,et al.Scholarly publishing in the Internet age:A citation analysis of computer science literature.Information Processing and Management,2001,37:661-675.2 Fernandez,M.,Kadiyska,Y.,&Suciu,D.,et al.SilkRoute:A framework for publishing relational data in XML.ACM Transactions on Database Systems,2002,27(4):438-493.

  4. Reference Citation Format

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    <正>The format for citations in text and for bibliographic references follows the Publication Manual of the American Psychological Association(5thEd.,2001)and GB/T 7714-2005.The citation of printed word should be ordered in number as it appears in the text of the submitted article.For journal article1 Goodrum,A.A.,McCain,K.W.,&Lawrence,S.,et al.Scholarly publishing in the Internet age:A citation analysis of computer science literature.Information Processing and Management,2001,37:661-675.2 Fernandez,M.,Kadiyska,Y.,&Suciu,D.,et al.SilkRoute:A framework for publishing relational data in XML.ACM Transactions on Database Systems,2002,27(4):438-493.

  5. Reference Citation Format

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    <正>The format for citations in text and for bibliographic references follows the Publication Manual of the American Psychological Association(5thEd.,2001)and GB/T 7714-2005.The citation of printed word should be ordered in number as it appears in the text of the submitted article.For journal article1 Goodrum,A.A.,McCain,K.W.,&Lawrence,S.,et al.Scholarly publishing in the Internet age:A citation analysis of computer science literature.Information Processing and Management,2001,37:661-675.2 Fernandez,M.,Kadiyska,Y.,&Suciu,D.,et al.SilkRoute:A framework for publishing relational data in XML.ACM Transactions on Database Systems,2002,27(4):438-493.

  6. Recipes for planet formation

    Science.gov (United States)

    Meyer, Michael R.

    2009-11-01

    Anyone who has ever used baking soda instead of baking powder when trying to make a cake knows a simple truth: ingredients matter. The same is true for planet formation. Planets are made from the materials that coalesce in a rotating disk around young stars - essentially the "leftovers" from when the stars themselves formed through the gravitational collapse of rotating clouds of gas and dust. The planet-making disk should therefore initially have the same gas-to-dust ratio as the interstellar medium: about 100 to 1, by mass. Similarly, it seems logical that the elemental composition of the disk should match that of the star, reflecting the initial conditions at that particular spot in the galaxy.

  7. Group Formation in Economics

    Science.gov (United States)

    Demange, Gabrielle; Wooders, Myrna

    2005-01-01

    Broad and diverse ranges of activities are conducted within and by organized groups of individuals, including political, economic and social activities. These activities have recently become a subject of intense interest in economics and game theory. Some of the topics investigated in this collection are models of networks of power and privilege, trade networks, co-authorship networks, buyer-seller networks with differentiated products, and networks of medical innovation and the adaptation of new information. Other topics are social norms on punctuality, clubs and the provision of club goods and public goods, research and development and collusive alliances among corporations, and international alliances and trading agreements. While relatively recent, the literature on game theoretic studies of group formation in economics is already vast. This volume provides an introduction to this important literature on game-theoretic treatments of situations with networks, clubs, and coalitions, including some applications.

  8. Nuclear Pasta Formation

    CERN Document Server

    Schneider, A S; Hughto, J; Berry, D K

    2013-01-01

    The formation of complex nonuniform phases of nuclear matter, known as nuclear pasta, is studied with molecular dynamics simulations containing 51200 nucleons. A phenomenological nuclear interaction is used that reproduces the saturation binding energy and density of nuclear matter. Systems are prepared at an initial density of 0.10fm$^{-3}$ and then the density is decreased by expanding the simulation volume at different rates to densities of 0.01 fm$^{-3}$ or less. An originally uniform system of nuclear matter is observed to form spherical bubbles ("swiss cheese"), hollow tubes, flat plates ("lasagna"), thin rods ("spaghetti") and, finally, nearly spherical nuclei with decreasing density. We explicitly observe nucleation mechanisms, with decreasing density, for these different pasta phase transitions. Topological quantities known as Minkowski functionals are obtained to characterize the pasta shapes. Different pasta shapes are observed depending on the expansion rate. This indicates non equilibrium effects...

  9. Remote sensing and GIS approach for water-well site selection, southwest Iran

    Science.gov (United States)

    Rangzan, K.; Charchi, A.; Abshirini, E.; Dinger, J.

    2008-01-01

    The Pabdeh-Lali Anticline of northern Khuzestan province is located in southwestern Iran and occupies 790 km2. This structure is situated in the Zagros folded belt. As a result of well-developed karst systems in the anticlinal axis, the water supply potential is high and is drained by many peripheral springs. However, there is a scarcity of water for agriculture and population centers on the anticlinal flanks, which imposes a severe problem in terms of area development. This study combines remotely sensed (RS) data and a geographical information system (GIS) into a RSGIS technique to delineate new areas for groundwater development and specific sites for drilling productive water wells. Toward these goals, RS data were used to develop GIS layers for lithology, structural geology, topographic slope, elevation, and drainage density. Field measurements were made to create spring-location and groundwater-quality GIS layers. Subsequently, expert choice and relational methods were used in a GIS environment to conjunctively analyze all layers to delineate preferable regions and 43 individual sites in which to drill water wells. Results indicate that the most preferred areas are, in preferential order, within recent alluvial deposits, the Bakhtiyari Conglomerates, and the Aghajari Sandstone. The Asmari Limestone and other units have much lower potential for groundwater supplies. Potential usefulness of the RSGIS method was indicated when six out of nine producing wells recently drilled by the Khozestan Water and Power Authority (which had no knowledge of this study) were located in areas preferentially selected by this technique.

  10. Chinese Affixes and Word Formation

    Directory of Open Access Journals (Sweden)

    Fu Ruomei

    2014-05-01

    Full Text Available Chinese language is one of the typical isolated languages. It lacks morphological variation; part of speech has no morphological signs; the additional component of word formation is less; and the roots never change their forms. The major method of Chinese word formation is the combination of roots according to certain grammatical relations. Although the affix word formation is not part of mainstream Chinese word formation, affix-formation is still an integral part of the Chinese word-formation. Article used literature review, summarized the types and meanings of Chinese affixes. And meanwhile, article analyzed word formation function of Chinese Affixes and quasi-affixes. The Chinese quasi-affixes have stronger capabilities in forming new words, but development direction of Chinese quasi-affixes has to stand the test of time.

  11. Gas formation. Formation temperatures of thermogenic and biogenic methane.

    Science.gov (United States)

    Stolper, D A; Lawson, M; Davis, C L; Ferreira, A A; Santos Neto, E V; Ellis, G S; Lewan, M D; Martini, A M; Tang, Y; Schoell, M; Sessions, A L; Eiler, J M

    2014-06-27

    Methane is an important greenhouse gas and energy resource generated dominantly by methanogens at low temperatures and through the breakdown of organic molecules at high temperatures. However, methane-formation temperatures in nature are often poorly constrained. We measured formation temperatures of thermogenic and biogenic methane using a "clumped isotope" technique. Thermogenic gases yield formation temperatures between 157° and 221°C, within the nominal gas window, and biogenic gases yield formation temperatures consistent with their comparatively lower-temperature formational environments (<50°C). In systems where gases have migrated and other proxies for gas-generation temperature yield ambiguous results, methane clumped-isotope temperatures distinguish among and allow for independent tests of possible gas-formation models. PMID:24970083

  12. Modeling Formation of Globular Clusters: Beacons of Galactic Star Formation

    CERN Document Server

    Gnedin, Oleg Y

    2010-01-01

    Modern hydrodynamic simulations of galaxy formation are able to predict accurately the rates and locations of the assembly of giant molecular clouds in early galaxies. These clouds could host star clusters with the masses and sizes of real globular clusters. I describe current state-of-the-art simulations aimed at understanding the origin of the cluster mass function and metallicity distribution. Metallicity bimodality of globular cluster systems appears to be a natural outcome of hierarchical formation and gradually declining fraction of cold gas in galaxies. Globular cluster formation was most prominent at redshifts z>3, when massive star clusters may have contributed as much as 20% of all galactic star formation.

  13. Formation of "bound

    Science.gov (United States)

    Nowak, K.; Kästner, M.; Miltner, A.

    2009-04-01

    During degradation of organic pollutants in soil, metabolites, microbial biomass, CO2and "bound" residues ("non-extractable" residues in soil organic matter) are formed. Enhanced transformation of these contaminants into "bound" residues has been proposed as an alternative remediation method for polluted soils. However, this kind of residues may pose a potential risk for the environment due to their chemical structure and possible remobilization under different conditions. Therefore particular attention is given actually to "bound" residues. Part of these non-extractable residues may be "biogenic," because microorganisms use the carbon from the pollutant to form their biomass components (fatty acids, amino acids, amino sugars), which subsequently may be incorporated into soil organic matter. Furthermore, the CO2 originating from mineralization of xenobiotics, can be re-assimilated by microorganisms and also incorporated into "biogenic residue". The hazard posed by "bound" residues may be overestimated because they are "biogenic" (contain microbial fatty acids and amino acids). The knowledge about the pathways of "biogenic residue" formation is necessary for a proper assessment of the fate of tested pollutants and their turnover in the soil environment. Moreover, these data are needed to establish the realistic degradation rates of the contaminants in soil. The main objectives of this study are: to quantify the extent of "biogenic residue" (fatty acids, amino acids, amino sugars) formation during the degradation of a model pollutant (2,4-dichlorophenoxyacetic acid = 2,4-D) and during CO2 assimilation by microorganisms and to evaluate which components are mainly incorporated into "bound" residues. To investigate the extent of "biogenic residue" formation in soil during the degradation of 2,4-D, experiments with either 14C-U-ring and 13C6-2,4-D or carboxyl-14C 2,4-D were performed. The incubation experiments were performed according to OECD test guideline 307, in the

  14. ISLET FORMATION AND REGENERATION

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Objective To explore the mechanisms of differentiation and development of pancreatic endocrine cells as well as pancreatic regeneration. Methods Human embryonic pancreatic tissue at 7-14 weeks of gestation was collected. Diabetes mellitus rat model was induced with 65 mg/kg of streptozotocin. Insulin, glucagon, somatostatin, nestin, and cytokeratin 19 (CK19)of pancreatic tissues were observed by immunohistochemistry. Results At 9 weeks of gestation, pancreatic epithelial cells began to co-express insulin, glucagon, somatostatin, and CK19 before migration. Islet cells gradually congregated along with the increase of aging, and at 14 weeks of gestation histological examination showed islet formation. At 12 weeks of gestation, nestin-positive cells could be seen in the pancreatic mesenchyme. During early embryogenesis, islet cells of pancreatic ducts co-expressed insulin, glucagon, and somatostatin. During pancreatic regeneration after damage, nestin expression of islet cells increased. Conclusion In the early stage of embryogenesis, islet cells of primary pancreatic ducts can be differentiated to multipotential endocrine cells before migration. During tissue regeneration, pancreatic stem cells may differentiate and proliferate to form pancreatic islet.

  15. The KEA image file format

    Science.gov (United States)

    Bunting, Peter; Gillingham, Sam

    2013-08-01

    There are a large number of image formats already in use within the remote sensing community but currently there is no format that provides the features of: compression, support for large file sizes, ground control points, raster attribute tables and inbuilt image pyramids. Therefore, a new image format, named KEA, after the New Zealand bird, has been proposed. The KEA format provides a full implementation of the GDAL data model and is implemented within a HDF5 file. A software library with a GDAL driver have been freely provided to the community allowing use through any GDAL based software. The new format has comparable performance with existing formats while producing smaller file sizes and is already within active use for a number of projects within Landcare Research, New Zealand, and the wider community.

  16. Earth and Terrestrial Planet Formation

    OpenAIRE

    Jacobson, Seth A.; Walsh, Kevin J.

    2015-01-01

    The growth and composition of Earth is a direct consequence of planet formation throughout the Solar System. We discuss the known history of the Solar System, the proposed stages of growth and how the early stages of planet formation may be dominated by pebble growth processes. Pebbles are small bodies whose strong interactions with the nebula gas lead to remarkable new accretion mechanisms for the formation of planetesimals and the growth of planetary embryos. Many of the popular models for ...

  17. Spray formation: an inverse cascade

    CERN Document Server

    Ling, Yue; Tryggvason, Gretar; zaleski, Stephane

    2015-01-01

    We present a study of droplet formation in a gas-liquid mixing layer using direct numerical simulation. It is seen that two mechanisms compete to generate the droplets: fingering at the tip of the waves and hole formation in the thin liquid sheet. The three dimensional liquid structures are much shorter than the longitudinal wavelength of the instability at the first instant of their formation. As time evolves, the structures evolves to larger and larger scales, in a way similar to the inverse cascade of length scales in droplet impact and impact crown formation.

  18. Formation of Bidisperse Particle Clouds

    Science.gov (United States)

    Er, Jenn Wei; Zhao, Bing; Law, Adrian W. K.; Adams, E. Eric

    2014-11-01

    When a group of dense particles is released instantaneously into water, their motion has been conceptualized as a circulating particle thermal (Ruggerber 2000). However, Wen and Nacamuli (1996) observed the formation of particle clumps characterized by a narrow, fast moving core shedding particles into wakes. They observed the clump formation even for particles in the non-cohesive range as long as the source Rayleigh number was large (Ra > 1E3) or equivalently the source cloud number (Nc) was small (Nc < 3.2E2). This physical phenomenon has been investigated by Zhao et al. (2014) through physical experiments. They proposed the theoretical support for Nc dependence and categorized the formation processes into cloud formation, transitional regime and clump formation. Previous works focused mainly on the behavior of monodisperse particles. The present study further extends the experimental investigation to the formation process of bidisperse particles. Experiments are conducted in a glass tank with a water depth of 90 cm. Finite amounts of sediments with various weight proportions between coarser and finer particles are released from a cylindrical tube. The Nc being tested ranges from 6E-3 to 9.9E-2, which covers all the three formation regimes. The experimental results showed that the introduction of coarse particles promotes cloud formation and reduce the losses of finer particles into the wake. More quantitative descriptions of the effects of source conditions on the formation processes will be presented during the conference.

  19. The formation of Pangea

    Science.gov (United States)

    Stampfli, G. M.; Hochard, C.; Vérard, C.; Wilhem, C.; vonRaumer, J.

    2013-05-01

    The making of Pangea is the result of large-scale amalgamation of continents and micro-continents, which started at the end of the Neoproterozoic with the formation of Gondwana. As pieces were added to Gondwana on its South-American, Antarctica and Australia side, ribbon-like micro-continents were detached from its African and South-Chinese side: Cadomia in the late Neoproterozoic, Avalonia and Hunia in the Ordovician, Galatia in the Devonian and Cimmeria in the Permian. Cadomia was re-accreted to Gondwana, but the other ribbon-continents were accreted to Baltica, North-China, Laurussia or Laurasia. Finding the origin of these numerous terranes is a major geological challenge. Recently, a global plate tectonic model was developed together with a large geological/geodynamic database, at the Lausanne University, covering the last 600 Ma of the Earth's history. Special attention was given to the placing of Gondwana derived terranes in their original position, using all possible constraints. We propose here a solution for the Variscan terranes, another paper deals with the Altaids. The Galatian super-terrane was detached from Gondwana in the Devonian, during the opening of Paleotethys, and was quickly separated into four sub-terranes that started to by-pass each other. The leading terranes collided at the end of the Devonian with the Hanseatic terrane detached from Laurussia. In the Carboniferous, Gondwana started to impinge onto the amalgamated terranes, creating the Variscan chain and the Pangean super-continent. East of Spain Paleotethys remained opened until the Triassic, subducting northward under Laurasia. Roll-back of the Paleotethyan slab triggered the collapse of most of the European Variscan orogen, which was replaced by series of Permian rifts, some of them becoming oceanized back-arc basins during the Triassic. Major force changes at the Pangean plate limits at the end of the Triassic provoked its break-up, through the opening of the proto

  20. Target-point formation control

    NARCIS (Netherlands)

    Mou, Shaoshuai; Cao, Ming; Morse, A. Stephen

    2015-01-01

    In this paper a new distributed feedback strategy is proposed for controlling a rigid, acyclic formation of kinematic point-modeled mobile autonomous agents in the plane. The strategy makes use of a new concept called a "target point" and is applicable to any two-dimensional, acyclic formation whose

  1. Identity formation in multiparty negotiations

    NARCIS (Netherlands)

    Swaab, R; Postmes, T.; Spears, R.

    2008-01-01

    Based on the recently proposed Interactive Model of Identity Formation, we examine how top-down deductive and bottom-up inductive identity formations influence intentions and behaviour in multiparty negotiations. Results show that a shared identity can be deduced from the social context through reco

  2. Pathogenesis of postoperative adhesion formation

    NARCIS (Netherlands)

    Hellebrekers, B.W.J.; Kooistra, T.

    2011-01-01

    Background: Current views on the pathogenesis of adhesion formation are based on the "classical concept of adhesion formation", namely that a reduction in peritoneal fibrinolytic activity following peritoneal trauma is of key importance in adhesion development. Methods: A non-systematic literature s

  3. Portable File Format (PFF) specifications.

    Energy Technology Data Exchange (ETDEWEB)

    Dolan, Daniel H.,

    2015-02-01

    Created at Sandia National Laboratories, the Portable File Format (PFF) allows binary data transfer across computer platforms. Although this capability is supported by many other formats, PFF files are still in use at Sandia, particularly in pulsed power research. This report provides detailed PFF specifications for accessing data without relying on legacy code.

  4. Formative assessments as pedagogic tools

    Directory of Open Access Journals (Sweden)

    Ashwin Kumar

    2013-03-01

    Full Text Available This article aims at presenting a state of the art status of formative assessment as a pedagogic tool. To this end, a brief developmental account of different modes of assessment over the last decades will be presented first. Then, formative assessment will be discussed in its constructivist guise. The present literature on assessment suggests that assessment for learning (formative assessment not only represents an assessment tool but it also serves as a pedagogic tool to enhance learning and thinking. It has also gone to lengths to affect the design of classroom tasks and activities. Attempts have been made to delineate the underlying principles of formative assessment which can be used to picture the formation process of learners’ knowledge and development. Subsequently, alternative assessment techniques of which the present article will give an account have been suggested by scholars to operationalize these principles.

  5. Physics of primordial star formation

    Science.gov (United States)

    Yoshida, Naoki

    2012-09-01

    The study of primordial star formation has a history of nearly sixty years. It is generally thought that primordial stars are one of the key elements in a broad range of topics in astronomy and cosmology, from Galactic chemical evolution to the formation of super-massive blackholes. We review recent progress in the theory of primordial star formation. The standard theory of cosmic structure formation posits that the present-day rich structure of the Universe developed through gravitational amplification of tiny matter density fluctuations left over from the Big Bang. It has become possible to study primordial star formation rigorously within the framework of the standard cosmological model. We first lay out the key physical processes in a primordial gas. Then, we introduce recent developments in computer simulations. Finally, we discuss prospects for future observations of the first generation of stars.

  6. Formation depths of Fraunhofer lines

    CERN Document Server

    Gurtovenko, E A

    2015-01-01

    We have summed up our investigations performed in 1970--1993. The main task of this paper is clearly to show processes of formation of spectral lines as well as their distinction by validity and by location. For 503 photospheric lines of various chemical elements in the wavelength range 300--1000 nm we list in Table the average formation depths of the line depression and the line emission for the line centre and on the half-width of the line, the average formation depths of the continuum emission as well as the effective widths of the layer of the line depression formation. Dependence of average depths of line depression formation on excitation potential, equivalent widths, and central line depth are demonstrated by iron lines.

  7. Dwarf galaxy formation with H2-regulated star formation

    CERN Document Server

    Kuhlen, M; Madau, P; Smith, B; Wise, J

    2011-01-01

    We describe cosmological galaxy formation simulations with the adaptive mesh refinement code Enzo that incorporate a star formation prescription regulated by the local abundance of molecular hydrogen. We show that this H2-regulated prescription leads to a suppression of star formation in low mass halos (M_h 4, alleviating some of the dwarf galaxy problems faced by theoretical galaxy formation models. H2 regulation modifies the efficiency of star formation of cold gas directly, rather than indirectly reducing the cold gas content with "supernova feedback". We determine the local H2 abundance in our most refined grid cells (76 proper parsec in size at z=4) by applying the model of Krumholz, McKee, & Tumlinson, which is based on idealized 1D radiative transfer calculations of H2 formation-dissociation balance in ~100 pc atomic--molecular complexes. Our H2-regulated simulations are able to reproduce the empirical (albeit lower z) Kennicutt-Schmidt relation, including the low Sigma_gas cutoff due to the transi...

  8. SOME QUESTIONS CONCERNING PSYCHOANALYTICAL FORMATION

    Directory of Open Access Journals (Sweden)

    Orlando Soeiro Cruxên

    2009-12-01

    Full Text Available The psychoanalytical formation is a question without a definitive answer. The development of its study requests treatment of the evolution of the clinical theory. This work begins with a distinction between analytical and academic formation. It includes Jacques Lacan’s approach concerning the question of psychoanalytical formation. It discusses the relationship between the named intentional and extensional psychoanalysis. This article resumes some theoretical aspects of a post-doctoral investigation developed in the clinical-school of Psychology (Universidade Federal do Ceará e SAP ( Pontifícia Universidade Católica do Rio Grande doSul.

  9. AGN feedback in galaxy formation

    CERN Document Server

    Antonuccio-Delogu, Vincenzo

    2010-01-01

    During the past decade, convincing evidence has been accumulated concerning the effect of active galactic nuclei (AGN) activity on the internal and external environment of their host galaxies. Featuring contributions from well-respected researchers in the field, and bringing together work by specialists in both galaxy formation and AGN, this volume addresses a number of key questions about AGN feedback in the context of galaxy formation. The topics covered include downsizing and star-formation time scales in massive elliptical galaxies, the connection between the epochs of supermassive black h

  10. Free-format RPG IV

    CERN Document Server

    Martin, Jim

    2013-01-01

    This how-to guide offers a concise and thorough introduction to the increased productivity, better readability, and easier program maintenance that comes with the free-format style of programming in RPG IV. Although free-format information is available in IBM manuals, it is not separated from everything else, thereby requiring hours of tedious research to track down the information needed. This book provides everything one needs to know to write RPG IV in the free-format style, and author Jim Martin not only teaches rules and syntax but also explains how this new style of coding has the pot

  11. Portfolio Optimization under Habit Formation

    CERN Document Server

    Naryshkin, Roman

    2008-01-01

    The "standard" Merton formulation of optimal investment and consumption involves optimizing the integrated lifetime utility of consumption, suitably discounted, together with the discounted future bequest. In this formulation the utility of consumption at any given time depends only on the amount consumed at that time. However, it is both theoretically and empirically reasonable that an individuals utility of consumption would depend on past consumption history. Economists term this "Habit Formation". We introduce a new formulation of habit formation which allows non-addictive consumption patterns for a wide variety of utility specification. In this paper we construct a simple mathematical description of this habit formation and present numerical solutions. We compare the results with the standard ones and draw insights obtained from the habit formation. The consumption path tends to increase with time and be less sensitive to the market fluctuations, which perfectly reflects the existence of habit persistenc...

  12. The multifaceted planetesimal formation process

    CERN Document Server

    Johansen, Anders; Tanaka, Hidekazu; Ormel, Chris; Bizzarro, Martin; Rickman, Hans

    2014-01-01

    Accumulation of dust and ice particles into planetesimals is an important step in the planet formation process. Planetesimals are the seeds of both terrestrial planets and the solid cores of gas and ice giants forming by core accretion. Left-over planetesimals in the form of asteroids, trans-Neptunian objects and comets provide a unique record of the physical conditions in the solar nebula. Debris from planetesimal collisions around other stars signposts that the planetesimal formation process, and hence planet formation, is ubiquitous in the Galaxy. The planetesimal formation stage extends from micrometer-sized dust and ice to bodies which can undergo run-away accretion. The latter ranges in size from 1 km to 1000 km, dependent on the planetesimal eccentricity excited by turbulent gas density fluctuations. Particles face many barriers during this growth, arising mainly from inefficient sticking, fragmentation and radial drift. Two promising growth pathways are mass transfer, where small aggregates transfer u...

  13. Robust Decentralized Formation Flight Control

    Directory of Open Access Journals (Sweden)

    Zhao Weihua

    2011-01-01

    Full Text Available Motivated by the idea of multiplexed model predictive control (MMPC, this paper introduces a new framework for unmanned aerial vehicles (UAVs formation flight and coordination. Formulated using MMPC approach, the whole centralized formation flight system is considered as a linear periodic system with control inputs of each UAV subsystem as its periodic inputs. Divided into decentralized subsystems, the whole formation flight system is guaranteed stable if proper terminal cost and terminal constraints are added to each decentralized MPC formulation of the UAV subsystem. The decentralized robust MPC formulation for each UAV subsystem with bounded input disturbances and model uncertainties is also presented. Furthermore, an obstacle avoidance control scheme for any shape and size of obstacles, including the nonapriorily known ones, is integrated under the unified MPC framework. The results from simulations demonstrate that the proposed framework can successfully achieve robust collision-free formation flights.

  14. Problem of professional personality formation

    Directory of Open Access Journals (Sweden)

    Pryazhnikova E.Yu.

    2012-09-01

    Full Text Available The article presents the current approaches to the problem of professional personality formation. It ana-lyzes the impact of professional identity of students on the choice of the specialist field they make. The article highlights certain aspects of the educational environment which promote to formation of compe-tences in students, relating to their choice of professional occupations. The article presents the analysis of students’ internal and external strivings after graduation from the university and their fulfillment.

  15. Electronic formation of a contract:

    OpenAIRE

    Kežmah, Urška

    2001-01-01

    This paper analysis main legal problems that are related to formation of e-contracts. Because of the different legal consequences it is highly important for parties to be aware and understand the basic phases of contract formation process. For a contract to exist, usually one party must have made offer, and the other must have accepted it. Once acceptance takes effect, a contract will usually be binding on both parties. A variety of procedures are available for forming an electronic contract,...

  16. EPR dosimetric properties of formates

    International Nuclear Information System (INIS)

    As a part of a program to develop an electron paramagnetic resonance (EPR) dosimeter suited for clinical use (doses in the cGy range), polycrystalline samples of lithium formate monohydrate (HCO2Li·H2O), magnesium formate dihydrate (C2H2O4Mg·2H2O), and calcium formate (C2H2O4Ca) have been examined. L-Alanine was included for comparison and reference. Samples were irradiated with 60Co γ-rays and 60-220 kV X-rays. The dosimeter response was assessed using the peak-to-peak amplitude of the first-derivative EPR spectrum. Dose-response curves for the 60Co γ-irradiated samples were constructed, and the dependences of the response on the photon energy, microwave power, and modulation amplitude were studied. Stability of the irradiation products upon storage (signal fading) was also investigated. Lithium formate monohydrate is by far the best candidate of the tested formates, suitable for measuring doses down to approximately 0.1 Gy. Lithium formate monohydrate is more sensitive than alanine by a factor of 5.6-6.8 in the tested photon energy range, it exhibits no zero-dose signal and shows a linear dose response in the dose range from 0.2 to 1000 Gy. Its EPR signal was found unchanged in shape and intensity 1 week after irradiation to 10 Gy. Various less favorable properties rendered the other formates generally unsuitable, although calcium formate exhibits some interesting EPR dosimetric properties

  17. Political parties and network formation

    OpenAIRE

    Miettinen, Topi; Poutvaara, Panu

    2006-01-01

    We argue that anti-corruption laws may provide an efficiency rationale for why political parties should meddle in the distribution of political nominations and government contracts. Anti-corruption laws forbid trade in spoils that politicians distribute. However, citizens may pay for gaining access to politicians and, thereby, to become potential candidates for nominations. Such rent-seeking results in excessive network formation. Political parties may reduce wasteful network formation, thank...

  18. Immigration, Integration and Ghetto Formation

    Science.gov (United States)

    Meyer-Ortmanns, Hildegard

    We study ghetto formation in a population with natives and immigrants in the framework of the two-dimensional Ising-model with Kawasaki-exchange dynamics. It is the phase structure of the Ising model, the integration speed and the immigration rate which determine whether ghetto formation between natives and immigrants can be avoided or not. Our simulations are performed in- and out-of-equilibrium.

  19. Immigration, integration and ghetto formation

    OpenAIRE

    Meyer-Ortmanns, Hildegard

    2002-01-01

    We study ghetto formation in a population with natives and immigrants in the framework of the two-dimensional Ising-model with Kawasaki-exchange dynamics. It is the phase structure of the Ising model, the integration speed and the immigration rate which determine whether ghetto formation between natives and immigrants can be avoided or not. Our simulations are performed in and out-of equilibrium.

  20. Chain formation of metal atoms

    DEFF Research Database (Denmark)

    Bahn, Sune Rastad; Jacobsen, Karsten Wedel

    2001-01-01

    The possibility of formation of single-atomic chains by manipulation of nanocontacts is studied for a selection of metals (Ni, Pd, Pt, Cu, Ag, Au). Molecular dynamics simulations show that the tendency for chain formation is strongest for Au and Pt. Density functional theory calculations indicate...... that the metals which form chains exhibit pronounced many-atom interactions with strong bonding in low coordinated systems....

  1. Treating tar sands formations with karsted zones

    Energy Technology Data Exchange (ETDEWEB)

    Vinegar, Harold J. (Bellaire, TX); Karanikas, John Michael (Houston, TX)

    2010-03-09

    Methods for treating a tar sands formation are described herein. The tar sands formation may have one or more karsted zones. Methods may include providing heat from one or more heaters to one or more karsted zones of the tar sands formation to mobilize fluids in the formation. At least some of the mobilized fluids may be produced from the formation.

  2. Star formation and structure formation in galaxy collisions

    CERN Document Server

    Bournaud, Frederic

    2009-01-01

    A number of theoretical and simulation results on star and structure formation in galaxy interactions and mergers is reviewed, and recent hydrodynamic simulations are presented. The role of gravity torques and ISM turbulence in galaxy interactions, in addition to the tidal field, is highlighted. Interactions can drive gas inflows towards the central kpc and trigger a central starburst, the intensity and statistical properties of which are discussed. A kinematically decoupled core and a supermassive central black hole can be fueled. Outside of the central kpc, many structures can form inside tidal tails, collisional ring, bridges, including super star clusters and tidal dwarf galaxies. The formation of super star clusters in galaxy mergers can now be directly resolved in hydrodynamic simulations. Their formation mechanisms and long-term evolution are reviewed, and the connection with present-day early-type galaxies is discussed.

  3. The dynamics of latifundia formation.

    Science.gov (United States)

    Chaves, Luis Fernando

    2013-01-01

    Land tenure inequity is a major social problem in developing nations worldwide. In societies, where land is a commodity, inequities in land tenure are associated with gaps in income distribution, poverty and biodiversity loss. A common pattern of land tenure inequities through the history of civilization has been the formation of latifundia [Zhuāngyuán in chinese], i.e., a pattern where land ownership is concentrated by a small fraction of the whole population. Here, we use simple Markov chain models to study the dynamics of latifundia formation in a heterogeneous landscape where land can transition between forest, agriculture and recovering land. We systematically study the likelihood of latifundia formation under the assumption of pre-capitalist trade, where trade is based on the average utility of land parcels belonging to each individual landowner during a discrete time step. By restricting land trade to that under recovery, we found the likelihood of latifundia formation to increase with the size of the system, i.e., the amount of land and individuals in the society. We found that an increase of the transition rate for land use changes, i.e., how quickly land use changes, promotes more equitable patterns of land ownership. Disease introduction in the system, which reduced land profitability for infected individual landowners, promoted the formation of latifundia, with an increased likelihood for latifundia formation when there were heterogeneities in the susceptibility to infection. Finally, our model suggests that land ownership reforms need to guarantee an equitative distribution of land among individuals in a society to avoid the formation of latifundia. PMID:24376597

  4. The dynamics of latifundia formation.

    Directory of Open Access Journals (Sweden)

    Luis Fernando Chaves

    Full Text Available Land tenure inequity is a major social problem in developing nations worldwide. In societies, where land is a commodity, inequities in land tenure are associated with gaps in income distribution, poverty and biodiversity loss. A common pattern of land tenure inequities through the history of civilization has been the formation of latifundia [Zhuāngyuán in chinese], i.e., a pattern where land ownership is concentrated by a small fraction of the whole population. Here, we use simple Markov chain models to study the dynamics of latifundia formation in a heterogeneous landscape where land can transition between forest, agriculture and recovering land. We systematically study the likelihood of latifundia formation under the assumption of pre-capitalist trade, where trade is based on the average utility of land parcels belonging to each individual landowner during a discrete time step. By restricting land trade to that under recovery, we found the likelihood of latifundia formation to increase with the size of the system, i.e., the amount of land and individuals in the society. We found that an increase of the transition rate for land use changes, i.e., how quickly land use changes, promotes more equitable patterns of land ownership. Disease introduction in the system, which reduced land profitability for infected individual landowners, promoted the formation of latifundia, with an increased likelihood for latifundia formation when there were heterogeneities in the susceptibility to infection. Finally, our model suggests that land ownership reforms need to guarantee an equitative distribution of land among individuals in a society to avoid the formation of latifundia.

  5. PCDF formation from PAH reactions

    Energy Technology Data Exchange (ETDEWEB)

    Fullana, A.; Nakka, H.; Sidhu, S. [Dayton Univ., OH (United States). Environmental Engineering

    2004-09-15

    It is clear that PAHs play an important role in PCDF formation. It does not matter if PCDF are formed from carbonaceous material or from PAH adsorbed on the carbon surface. The role of PAH in the formation of PCDF has been studied by several authors. Probably one of the most complete investigations was conducted by Wilhelm et al. They investigated PCDF formation from twelve different PAHs with structures similar to the PCDF. The results of this study showed that biphenyl-like structures can be easily converted to PCDFs. Although the biphenyl-like structures are clearly involved in PCDF formation, there are several aspects of this formation pathway that are not well understood. Iino et al. found that higher PCDF yields could be obtained from pyrene than phenanthrene, contradicting biphenyl intermediate formation pathway theory as phenantrene structure can more easily be converted to biphenyl than pyrene. All previous PCDD/F formation studies from PAHs were conducted using CuCl{sub 2} as model fly ash. CuCl{sub 2} is highly volatile and probably not present in any significant quantities in the actual fly ash. High temperature oxidative conditions in the high temperature zone are able to oxidize all transition metals to their oxides. Therefore, Cu in actual fly ash is most probably present as CuO or Cu2O. Also in previous studies, PAH - model fly ash mixtures were prepared at room temperature and then heated to experimental temperatures. This experimental method can lead to some uncertainties because depending on PAH boiling point, various amounts of different PAHS would have evaporated by the time experimental temperatures were achieved. The main objective of this study is to address all the above issues and develop a better understanding of the role of biphenyl structures in PCDF formation. The salient features of this study are: Use of CuO+HCl as model fly ash instead of CuCl{sub 2} which was traditionally used in earlier De Novo studies. Study major non

  6. Star formation in Galactic flows

    Science.gov (United States)

    Smilgys, Romas; Bonnell, Ian A.

    2016-06-01

    We investigate the triggering of star formation in clouds that form in Galactic scale flows as the interstellar medium passes through spiral shocks. We use the Lagrangian nature of smoothed particle hydrodynamics simulations to trace how the star-forming gas is gathered into self-gravitating cores that collapse to form stars. Large-scale flows that arise due to Galactic dynamics create shocks of the order of 30 km s-1 that compress the gas and form dense clouds (n > several × 102 cm-3) in which self-gravity becomes relevant. These large-scale flows are necessary for creating the dense physical conditions for gravitational collapse and star formation. Local gravitational collapse requires densities in excess of n > 103 cm-3 which occur on size scales of ≈1 pc for low-mass star-forming regions (M 103 M⊙). Star formation in the 250 pc region lasts throughout the 5 Myr time-scale of the simulation with a star formation rate of ≈10-1 M⊙ yr-1 kpc-2. In the absence of feedback, the efficiency of the star formation per free-fall time varies from our assumed 100 per cent at our sink accretion radius to values of <10-3 at low densities.

  7. Resolving the Formation of Protogalaxies

    CERN Document Server

    Wise, John H

    2007-01-01

    Cosmic structure originated from minute density perturbations in an almost homogeneous universe. The first stars are believed to be very massive and luminous, providing the first ionizing radiation and heavy elements to the universe and forming 100 million years after the Big Bang. The impact from primordial stellar radiation is far reaching and affects subsequent star and galaxy formation. In this thesis, we present results from adaptive mesh refinement calculations of the formation of the first galaxies. We gradually introduce important physical processes, such as molecular hydrogen cooling and stellar feedback, to base models that only consider atomic hydrogen and helium cooling. In these base models, we find that gas in dark matter halos with masses ~10^8 solar masses centrally collapse before multiple fragmentation occurs in a global disc. We then investigate the importance of molecular hydrogen cooling in early structure formation in the presence of a soft ultraviolet radiation background. We find that ...

  8. Black holes and galaxy formation

    CERN Document Server

    Propst, Raphael J

    2010-01-01

    Galaxies are the basic unit of cosmology. The study of galaxy formation is concerned with the processes that formed a heterogeneous universe from a homogeneous beginning. The physics of galaxy formation is complicated because it deals with the dynamics of stars, thermodynamics of gas and energy production of stars. A black hole is a massive object whose gravitational field is so intense that it prevents any form of matter or radiation to escape. It is hypothesized that the most massive galaxies in the universe- "elliptical galaxies"- grow simultaneously with the supermassive black holes at their centers, giving us much stronger evidence that black holes control galaxy formation. This book reviews new evidence in the field.

  9. Formation of porous gas hydrates

    CERN Document Server

    Salamatin, Andrey N

    2015-01-01

    Gas hydrates grown at gas-ice interfaces are examined by electron microscopy and found to have a submicron porous texture. Permeability of the intervening hydrate layers provides the connection between the two counterparts (gas and water molecules) of the clathration reaction and makes further hydrate formation possible. The study is focused on phenomenological description of principal stages and rate-limiting processes that control the kinetics of the porous gas hydrate crystal growth from ice powders. Although the detailed physical mechanisms involved in the porous hydrate formation still are not fully understood, the initial stage of hydrate film spreading over the ice surface should be distinguished from the subsequent stage which is presumably limited by the clathration reaction at the ice-hydrate interface and develops after the ice grain coating is finished. The model reveals a time dependence of the reaction degree essentially different from that when the rate-limiting step of the hydrate formation at...

  10. Spatial competition and price formation

    Science.gov (United States)

    Nagel, Kai; Shubik, Martin; Paczuski, Maya; Bak, Per

    2000-12-01

    We look at price formation in a retail setting, that is, companies set prices, and consumers either accept prices or go someplace else. In contrast to most other models in this context, we use a two-dimensional spatial structure for information transmission, that is, consumers can only learn from nearest neighbors. Many aspects of this can be understood in terms of generalized evolutionary dynamics. In consequence, we first look at spatial competition and cluster formation without price. This leads to establishement size distributions, which we compare to reality. After some theoretical considerations, which at least heuristically explain our simulation results, we finally return to price formation, where we demonstrate that our simple model with nearly no organized planning or rationality on the part of any of the agents indeed leads to an economically plausible price.

  11. Bundle Formation in Biomimetic Hydrogels.

    Science.gov (United States)

    Jaspers, Maarten; Pape, A C H; Voets, Ilja K; Rowan, Alan E; Portale, Giuseppe; Kouwer, Paul H J

    2016-08-01

    Bundling of single polymer chains is a crucial process in the formation of biopolymer network gels that make up the extracellular matrix and the cytoskeleton. This bundled architecture leads to gels with distinctive properties, including a large-pore-size gel formation at very low concentrations and mechanical responsiveness through nonlinear mechanics, properties that are rarely observed in synthetic hydrogels. Using small-angle X-ray scattering (SAXS), we study the bundle formation and hydrogelation process of polyisocyanide gels, a synthetic material that uniquely mimics the structure and mechanics of biogels. We show how the structure of the material changes at the (thermally induced) gelation point and how factors such as concentration and polymer length determine the architecture, and with that, the mechanical properties. The correlation of the gel mechanics and the structural parameters obtained from SAXS experiments is essential in the design of future (synthetic) mimics of biopolymer networks.

  12. Dense Cloud Formation and Star Formation in a Barred Galaxy

    CERN Document Server

    Nimori, M; Sorai, K; Watanabe, Y; Hirota, A; Namekata, D

    2012-01-01

    We investigate the properties of massive, dense clouds formed in a barred galaxy and their possible relation to star formation, performing a two-dimensional hydrodynamical simulation with the gravitational potential obtained from the 2Mass data from the barred spiral galaxy, M83. Since the environment for cloud formation and evolution in the bar region is expected to be different from that in the spiral arm region, barred galaxies are a good target to study the environmental effects on cloud formation and the subsequent star formation. Our simulation uses for an initial 80 Myr an isothermal flow of non-self gravitating gas in the barred potential, then including radiative cooling, heating and self-gravitation of the gas for the next 40 Myr, during which dense clumps are formed. We identify many cold, dense gas clumps for which the mass is more than $10^4M_{\\odot}$ (a value corresponding to the molecular clouds) and study the physical properties of these clumps. The relation of the velocity dispersion of the i...

  13. Formation of the first stars

    International Nuclear Information System (INIS)

    Understanding the formation of the first stars is one of the frontier topics in modern astrophysics and cosmology. Their emergence signalled the end of the cosmic dark ages, a few hundred million years after the Big Bang, leading to a fundamental transformation of the early Universe through the production of ionizing photons and the initial enrichment with heavy chemical elements. We here review the state of our knowledge, separating the well understood elements of our emerging picture from those where more work is required. Primordial star formation is unique in that its initial conditions can be directly inferred from the Λ cold dark matter (ΛCDM) model of cosmological structure formation. Combined with gas cooling that is mediated via molecular hydrogen, one can robustly identify the regions of primordial star formation, the so-called minihalos, having total masses of ∼106 M⊙ and collapsing at redshifts z ≃ 20–30. Within this framework, a number of studies have defined a preliminary standard model, with the main result that the first stars were predominantly massive. This model has recently been modified to include a ubiquitous mode of fragmentation in the protostellar disks, such that the typical outcome of primordial star formation may be the formation of a binary or small multiple stellar system. We will also discuss extensions to this standard picture due to the presence of dynamically significant magnetic fields, of heating from self-annihalating WIMP dark matter, or cosmic rays. We conclude by discussing possible strategies to empirically test our theoretical models. Foremost among them are predictions for the upcoming James Webb space telescope (JWST), to be launched ∼2018, and for ‘stellar archaeology’, which probes the abundance pattern in the oldest, most-metal poor stars in our cosmic neighborhood, thereby constraining the nucleosynthesis inside the first supernovae. (review article)

  14. Conductive Anodic Filament (CAF) Formation

    Science.gov (United States)

    Caputo, Antonio

    Conductive anodic filament (CAF) is a failure mode in printed wiring boards (PWBs) which occurs under high humidity and high voltage gradient conditions. The filament, a copper salt, grows from anode to cathode along the epoxy-glass interface. Ready and Turbini (2000) identified this copper salt as the Cu 2(OH)3Cl, atacamite compound. This work has investigated the influence of polyethylene glycol (PEG) and polyethylene propylene glycol (PEPG) fluxing agents on the chemical nature of CAF. For coupons processed with PEPG flux, with and without chloride, a copper-chloride containing compound was formed in the polymer matrix. This compound was characterized using x-ray photoelectron spectroscopy (XPS) as CuCl and an electrochemical mechanism for the formation of the chloride-containing CAF has been proposed. For PEG flux, with and without chloride, it has been shown that CAF only formed, but no copper containing compound formed in the matrix. It appears for PEG fluxed coupons, a PEG-Cu-Cl complex forms, binds the available Cu and acts as a barrier to the formation of CuCl in the polymer matrix. Meeker and Lu Valle (1995) have previously proposed that CAF failure is best represented by two competing reactions -- the formation of a copper chloride corrosion compound (now identified as Cu2(OH)3Cl) and the formation of innocuous trapped chlorine compounds. Since no evidence of any trapped chloride compounds has been found, we propose that the formation of CAF is best represented by a single non-reversible reaction. For coupons processed with a high bromide-containing flux, bromide containing CAF was created and characterized using transmission electron microscopy (TEM) to be Cu2(OH)3Br. In addition, a copper-containing compound was formed in the polymer matrix and characterized using XPS as CuBr. An electrochemical mechanism for the formation of bromide-containing CAF has been proposed based on the XPS data.

  15. Prediction of tar ball formation

    Energy Technology Data Exchange (ETDEWEB)

    Khelifa, A.; Gamble, L. [Environment Canada, Ottawa, ON (Canada). Emergencies Science and Technology Division, Environmental Technology Centre, Science and Technology Branch

    2006-07-01

    The presence of small tar balls ranging in size from less than a millimetre to 60 centimetres have been observed during cleanup assessment operations following accidental oil spills on water. The tar balls are composed of heavy oil residues and suspended particulate matter (SPM) from the water column. They can be found on shorelines, settled on the seafloor and floating at or near the water surface. Their abundance on the shorelines varies from site to site and depends on the conditions of the spill and mixing conditions. Aggregation between SPM and micro-sized oil droplets occurs naturally in coastal waters and enhances the dispersion of spilled oil. Although tar balls are among the important end states of spilled oil in the marine environment, no model exists to estimate the percentage of the spilled oil that becomes tar balls. This paper offered some insight into the modeling of tar ball formation. Current modeling understanding of oil-SPM aggregate formation was used to predict tar ball formation. The formation of oil droplets was examined with respect to a range of conditions under which the formation of large droplets is expected. The role of aggregation was then presented to demonstrate the effects of concentration and type of SPM on the buoyancy of tar balls. Good agreement was found between modeling results and field data reported in the literature regarding the size and density of tar balls. Oil viscosity and mixing energy were found to be the main factors controlling the formation of tar balls. The aggregation of tar balls with SPM and shoreline material results in significant increases or decreases in density, depending on the type and concentration of SPM. 42 refs., 2 tabs., 6 figs.

  16. Formation of the First Stars

    OpenAIRE

    Bromm, Volker

    2005-01-01

    How and when did the first generation of stars form at the end of the cosmic dark ages? Quite generically, within variants of the cold dark matter model of cosmological structure formation, the first sources of light are expected to form in ~ 10^{6} M_sun dark matter potential wells at redshifts z > 20. I discuss the physical processes that govern the formation of the first stars. These so-called Population~III stars are predicted to be predominantly very massive, and to have contributed sign...

  17. Pattern formations and oscillatory phenomena

    CERN Document Server

    Kinoshita, Shuichi

    2013-01-01

    Patterns and their formations appear throughout nature, and are studied to analyze different problems in science and make predictions across a wide range of disciplines including biology, physics, mathematics, chemistry, material science, and nanoscience. With the emergence of nanoscience and the ability for researchers and scientists to study living systems at the biological level, pattern formation research has become even more essential. This book is an accessible first of its kind guide for scientists, researchers, engineers, and students who require a general introduction to thi

  18. High-Mass Star Formation

    CERN Document Server

    Schilke, Peter

    2016-01-01

    A review on current theories and observations of high-mass star formation is given. Particularly the influence of magnetic fields and feedback mechanisms, and of varying initial conditions on theories are discussed. The, in my biased view, most important observations to put strong constraints on models of high-mass star formation are pres ented, in particular bearing on the existence and properties of high-mass starless cores, the role of filaments in the mass transport to high-mass cores, and the propertie s of disks around high-mass stars.

  19. Magnetohydrodynamic mechanism for pedestal formation.

    Science.gov (United States)

    Guazzotto, L; Betti, R

    2011-09-16

    Time-dependent two-dimensional magnetohydrodynamic simulations are carried out for tokamak plasmas with edge poloidal flow. Differently from conventional equilibrium theory, a density pedestal all around the edge is obtained when the poloidal velocity exceeds the poloidal sound speed. The outboard pedestal is induced by the transonic discontinuity, the inboard one by mass redistribution. The density pedestal follows the formation of a highly sheared flow at the transonic surface. These results may be relevant to the L-H transition and pedestal formation in high performance tokamak plasmas.

  20. Star formation and gas supply

    Science.gov (United States)

    Catinella, B.

    2016-06-01

    A detailed knowledge of how gas cycles in and around galaxies, and how it depends on galaxy properties such as stellar mass and star formation rate, is crucial to understand galaxy formation and evolution. We take advantage of the most sensitive surveys of cold gas in massive galaxies, GASS and COLD GASS, as well as of the state-of-the-art HI blind survey ALFALFA to investigate how molecular and atomic hydrogen reservoirs vary along and across the main sequence of star-forming galaxies.

  1. Strategy Formation in Eastern Jutland

    DEFF Research Database (Denmark)

    Olesen, Kristian

    2008-01-01

      In Eastern Jutland a strategy formation process has been initiated with the aim of developing a strategic spatial plan for the city region.  An organisation has been set up to deal with the first phase of the process, which is to carry out three functional analyses and prepare a common vision...... on which level a serious strategy formation process can take place.  There is a danger that a common strategic spatial plan is more an expression of the lowest common denominator and the municipalities request for infrastructure investments rather than being a spatial strategy with transformative power. ...

  2. Comparative essential oil composition of aerial parts of Tanacetum dumosum Boiss. from Southern Zagros, Iran.

    Science.gov (United States)

    Ghanbarian, Gholam Abbas; Naseri, Mahmood; Hatami, Ahmad; Jafari, Efat

    2015-01-01

    The essential oils of leaves and flowers of Tanacetum dumosum Boiss., an endemic medicinal shrub, were extracted by using hydrodistillation method and analysed using GC and GC-MS. A total of 43 and 44 compounds were identified in the essential oils from the leaves and flowers of T. dumosum, respectively. The major chemical constituents of leaves oil were borneol (27.9%), bornyl acetate (18.4%), 1,8-cineol (17.5%), α-terpineol (5.3%), cis-chrysanthenyl acetate (3.3%), camphene (2.7%) and terpinene-4-ol (1.9%), while the main components of the flower oil were isobornyl-2-methyl butanoate (41.1%), trans-linalyl oxide acetate (11.9%), 1,8-cineole (7.7%), thymol (4.2%), linalool (3.9%), camphor (2.9%), isobornyl propanoate (2.9%), α-terpineol (2.1%) and caryophyllene oxide (2.0%). Major qualitative and quantitative variations for some main chemical compounds among different aerial parts of T. dumosum were identified. High contents of borneol, bornyl acetate, 1,8-cineol and linalool in the leaves and flowers of T. dumosum show its potential for use in the food and perfumery industry. PMID:25370611

  3. Internet – zagrożenie czy uzupełnienie tradycyjnej biblioteki?

    OpenAIRE

    Krupa, Zenona

    2006-01-01

    The paper is based on empirical examinations of the group of 143 students undergraduate and second year of full-time courses in higher education of the Rzeszów University of around three subjects: Polish philology, history, mathematics and 30 researchers for 10 persons from mentioned above. In examinations they used the questionnaire form and it was a pilotage of bigger examinations. The examination was aimed at showing the Internet really will become the risk for functioning of traditional l...

  4. Traditional silvopastoral management and its effects on forest stand structure in northern Zagros, Iran

    DEFF Research Database (Denmark)

    Valipour, Ahmad; Plieninger, Tobias; Shakeri, Zahed;

    2014-01-01

    Oak forests of Iran are managed for soil conservation, water quality and other non-market ecosystem services. Nationalization policies in 1963 implied shifts from private ownership and informal traditional management to public ownership and state forest management. In spite of the nationalization...

  5. Zagrożone gatunki roślin naczyniowych Kutna

    OpenAIRE

    Warcholińska, Urszula; Gmerek, Anna

    2002-01-01

    In this article a list and characterization of endangered species of vascular plants, found in the area of Kutno in 1992-1994, has been presented. The research was carried out using a cartogram method. Zadanie pt. „Digitalizacja i udostępnienie w Cyfrowym Repozytorium Uniwersytetu Łódzkiego kolekcji czasopism naukowych wydawanych przez Uniwersytet Łódzki” nr 885/P-DUN/2014 dofinansowane zostało ze środków MNiSW w ramach działalności upowszechniającej naukę.

  6. Macierzyństwo po rozwodzie. Szanse i zagrożenia

    OpenAIRE

    PIOTROWSKA, MAJA

    2014-01-01

    Results of social change which can be seen in the area of family life, especially include crisis of the institution of marriage, redefinition of parent's roles in the parenthood or monoparenthood. The role of the mother is socially important and appreciated. In the academic discourse on the contemporary motherhood, a category of single mother or independent mother appears increasingly. Monoparental family, like the ones in which the spouses got divorced, are becoming more visible form of t...

  7. Exciton Formation in Disordered Semiconductors

    DEFF Research Database (Denmark)

    Klochikhin, A.; Reznitsky, A.; Permogorov, S.;

    1999-01-01

    Stationary luminescence spectra of disordered solid solutions can be accounted by the model of localized excitons. Detailed analysis of the long time decay kinetics of luminescence shows that exciton formation in these systems is in great extent due to the bimolecular reaction of separated carrie...

  8. Constraints on galaxy formation theories

    Science.gov (United States)

    Szalay, A. S.

    1986-01-01

    The present theories of galaxy formation are reviewed. The relation between peculiar velocities, temperature fluctuations of the microwave background and the correlation function of galaxies point to the possibility that galaxies do not form uniformly everywhere. The velocity data provide strong constraints on the theories even in the case when light does not follow mass of the universe.

  9. The EPRDATA Format: A Dialogue

    Energy Technology Data Exchange (ETDEWEB)

    Hughes, Henry Grady III [Los Alamos National Laboratory

    2015-08-18

    Recently the Los Alamos Nuclear Data Team has communicated certain issues of concern in relation to the new electron/photon/relaxation ACE data format as released in the eprdata12 library. In this document those issues are parsed, analyzed, and answered.

  10. Earth and Terrestrial Planet Formation

    CERN Document Server

    Jacobson, Seth A

    2015-01-01

    The growth and composition of Earth is a direct consequence of planet formation throughout the Solar System. We discuss the known history of the Solar System, the proposed stages of growth and how the early stages of planet formation may be dominated by pebble growth processes. Pebbles are small bodies whose strong interactions with the nebula gas lead to remarkable new accretion mechanisms for the formation of planetesimals and the growth of planetary embryos. Many of the popular models for the later stages of planet formation are presented. The classical models with the giant planets on fixed orbits are not consistent with the known history of the Solar System, fail to create a high Earth/Mars mass ratio, and, in many cases, are also internally inconsistent. The successful Grand Tack model creates a small Mars, a wet Earth, a realistic asteroid belt and the mass-orbit structure of the terrestrial planets. In the Grand Tack scenario, growth curves for Earth most closely match a Weibull model. The feeding zon...

  11. Genetic analysis of symbiosome formation

    NARCIS (Netherlands)

    Ovchinnikova, E.

    2012-01-01

    Endosymbiotic interactions form a fundament of life as we know it and are characterized by the formation of new specialized membrane compartments, in which the microbes are hosted inside living plant cells. A striking example is the symbiosis between legumes and nitrogen-fixing Rhizobium bacteria (r

  12. Stereotype Formation : Biased by Association

    NARCIS (Netherlands)

    Le Pelley, Mike E.; Reimers, Stian J.; Calvini, Guglielmo; Spears, Russell; Beesley, Tom; Murphy, Robin A.

    2010-01-01

    We propose that biases in attitude and stereotype formation might arise as a result of learned differences ill the extent its which social groups have previously been predictive elf behavioral or physical properties Experiments 1 and 2 demonstrate that differences in the experienced predictiveness o

  13. Star formation in Galactic flows

    CERN Document Server

    Smilgys, R

    2016-01-01

    We investigate the triggering of star formation in clouds that form in Galactic scale flows as the ISM passes through spiral shocks. We use the Lagrangian nature of SPH simulations to trace how the star forming gas is gathered into self-gravitating cores that collapse to form stars. Large scale flows that arise due to Galactic dynamics create shocks of order 30 km/s that compress the gas and form dense clouds $(n> $several $\\times 10^2$ cm$^{-3}$) in which self-gravity becomes relevant. These large-scale flows are necessary for creating the dense physical conditions for gravitational collapse and star formation. Local gravitational collapse requires densities in excess of $n>10^3$ cm$^{-3}$ which occur on size scales of $\\approx 1$ pc for low-mass star forming regions ($M10^3 M_{\\odot}$). Star formation in the 250 pc region lasts throughout the 5 Myr timescale of the simulation with a star formation rate of $\\approx 10^{-1} M_{\\odot}$ yr$^{-1}$ kpc$^{-2}$. In the absence of feedback, the efficiency of the sta...

  14. Formative Assessment in Dance Education

    Science.gov (United States)

    Andrade, Heidi; Lui, Angela; Palma, Maria; Hefferen, Joanna

    2015-01-01

    Feedback is crucial to students' growth as dancers. When used within the framework of formative assessment, or assessment for learning, feedback results in actionable next steps that dancers can use to improve their performances. This article showcases the work of two dance specialists, one elementary and one middle school teacher, who have…

  15. Formation of Rationally Heterogeneous Expectations

    NARCIS (Netherlands)

    Pfajfar, D.

    2012-01-01

    Abstract: This paper models expectation formation by taking into account that agents produce heterogeneous expectations due to model uncertainty, informational frictions and different capacities for processing information. We show that there are two general classes of steady states within this frame

  16. The Road to Galaxy Formation

    CERN Document Server

    Keel, William C

    2007-01-01

    The formation of galaxies is one of the greatest puzzles in astronomy, the solution is shrouded in the depths of space and time, but has profound implications for the universe we observe today. The book discusses the beginnings of the process from cosmological observations and calculations, considers the broad features of galaxies that we need to explain and what we know of their later history. The author compares the competing theories for galaxy formation and considers the progress expected from new generations of powerful telescopes both on earth and in space. In this second edition the author has retained the observationally-based approach of the first edition, a feature which was particularly well-reviewed: Writing in Nature, Carlton Baugh noted in February 2003 that “It is refreshing, in a market dominated by theorists, to come across a book on galaxy formation written from an observational perspective. The Road to Galaxy Formation should prove to be a handy primer on observations for graduate student...

  17. Control over Administrative Contract Formation

    Directory of Open Access Journals (Sweden)

    Frane Staničić

    2016-02-01

    Full Text Available Administrative contracts in Croatian legislation represent a novelty introduced into the General Administration Procedure Act in 2010. This is a novelty which has not proved to be successful in practice. Control over administrative contract formation is inevitable and is very significant for a number of reasons. Firstly, public legal bodies which form them do so by exercising their own public powers which are without doubt subject to legality control; secondly, in forming administrative contracts, public funds are used which must be controlled; thirdly, forming administrative contracts often touches on using public goods. Due to the restrictive interpretation of administrative contracts in Croatian legislation, this institute is indisputably only regulated in the General Taxation Act. However, for more than two decades contracts which satisfy all presumptions have existed in our law in order to be considered as administrative contracts. It is for this reason that control over contracts will be dealt with for contracts considered by the author to be administrative contracts. These are contracts on concessions and contracts on public procurement. How inadequate today’s regulation of control of administrative contract formation is will be demonstrated, particularly regarding contracts on concession and public procurement. Legislative changes will be proposed which should result in a more quality system of control over administrative contract formation. How control over administrative contract formation cannot be considered as separate from control over administrative contract execution will also be shown.

  18. Wintertime Haze Formation in Beijing

    Science.gov (United States)

    Levy Zamora, M. E.

    2015-12-01

    Recent severe haze events in China have attracted significant public attention due to the severely reduced visibility and unprecedentedly high pollutant concentrations. Particular attention has been given to the high concentrations of particulate matter with a diameter less than 2.5 microns (PM2.5), which can exceed several hundred micrograms per cubic meter over several days. During January and February of 2015, a suite of aerosol instruments was deployed in Beijing to directly measure a comprehensive set of aerosol properties, including the particle size distribution, effective density, and chemical composition. In this presentation, we will discuss the particulate matter formation mechanisms, the evolution of aerosol properties throughout the event, and how the winter formation mechanisms compare with the warmer seasons. We show that the periodic cycles of severe haze episodes in Beijing are largely driven by meteorological conditions. During haze events, stagnation typically develops as a result of a low planetary boundary layer and weak southerly wind from polluted industrial source regions. Stronger northerly winds were frequently observed during the clean period, which carry unpolluted air masses from the less populated northern mountainous areas. Nucleation consistently occurs on clean days, producing a high number concentration of nano particles. The particle mass concentration exceeding several hundred micrograms per cubic meter is attributed to the continuous size growth from the nucleation-mode particles (diameter less than 10 nm) over multiple days to produce a high concentration of larger particles (diameter greater than 100 nm). The particle chemical composition in Beijing is similar to those commonly measured in other urban centers, which is indicative of chemical constituents dominated by secondary aerosol formation. Our results reveal that the severe haze formation in Beijing during the wintertime is similar to the mechanism of haze formation

  19. Sedimentary pyrite formation: An update

    Science.gov (United States)

    Berner, Robert A.

    1984-04-01

    Sedimentary pyrite formation during early diagenesis is a major process for controlling the oxygen level of the atmosphere and the sulfate concentration in seawater over geologic time. The amount of pyrite that may form in a sediment is limited by the rates of supply of decomposable organic matter, dissolved sulfate, and reactive detrital iron minerals. Organic matter appears to be the major control on pyrite formation in normal (non-euxinic) terrigenous marine sediments where dissolved sulfate and iron minerals are abundant. By contrast, pyrite formation in non-marine, freshwater sediments is severely limited by low concentrations of sulfate and this characteristic can be used to distinguish ancient organic-rich fresh water shales from marine shales. Under marine euxinic conditions sufficient H 2S is produced that the dominant control on pyrite formation is the availability of reactive iron minerals. Calculations, based on a sulfur isotope model, indicate that over Phanerozoic time the worldwide average organic carbon-to-pyrite sulfur ratio of sedimentary rocks has varied considerably. High C/S ratios during Permo-Carboniferous time can be explained by a shift of major organic deposition from the oceans to the land which resulted in the formation of vast coal swamps at that time. Low C/S ratios, compared to today, during the early Paleozoic can be explained in terms of a greater abundance of euxinic basins combined with deposition of a more reactive type of organic matter in the remaining oxygenated portions of the ocean. The latter could have been due to lower oceanic oxygen levels and/or a lack of transportation of refractory terrestrial organic matter to the marine environment due to the absence of vascular land plants at that time.

  20. Consensus formation on coevolving networks: groups' formation and structure

    International Nuclear Information System (INIS)

    We study the effect of adaptivity on a social model of opinion dynamics and consensus formation. We analyse how the adaptivity of the network of contacts between agents to the underlying social dynamics affects the size and topological properties of groups and the convergence time to the stable final state. We find that, while on static networks these properties are determined by percolation phenomena, on adaptive networks the rewiring process leads to different behaviors: adaptive rewiring fosters group formation by enhancing communication between agents of similar opinion, though it also makes possible the division of clusters. We show how the convergence time is determined by the characteristic time of link rearrangement. We finally investigate how the adaptivity yields nontrivial correlations between the internal topology and the size of the groups of agreeing agents

  1. Stratigraphy and dissolution of the Rustler Formation

    International Nuclear Information System (INIS)

    This report describes the physical stratigraphy of the Rustler Formation, because the Waste Isolation Pilot Plant will be constructed in salt beds that underlie this formation. Described are subdivisions of the formations, the major karst features, and a proposed method for the formation of Nash Draw. 2 refs., 2 figs

  2. Transparent Format Migration of Preserved Web Content

    OpenAIRE

    Rosenthal, David S. H.; Lipkis, Thomas; Robertson, Thomas; Morabito, Seth

    2005-01-01

    The LOCKSS digital preservation system collects content by crawling the web and preserves it in the format supplied by the publisher. Eventually, browsers will no longer understand that format. A process called format migration converts it to a newer format that the browsers do understand. The LOCKSS program has designed and tested an initial implementation of format migration for Web content that is transparent to readers, building on the content negotiation capabilities of HTTP.

  3. Treating tar sands formations with dolomite

    Energy Technology Data Exchange (ETDEWEB)

    Vinegar, Harold J.; Karanikas, John Michael

    2010-06-08

    Methods for treating a tar sands formation are described herein. The tar sands formation may include dolomite and hydrocarbons. Methods may include providing heat at less than the decomposition temperature of dolomite from one or more heaters to at least a portion of the formation. At least some of the hydrocarbon fluids are mobilized in the formation. At least some of the hydrocarbon fluids may be produced from the formation.

  4. Controlled Irradiative Formation of Penitentes

    CERN Document Server

    Bergeron, V; Betterton, M D

    2006-01-01

    Spike-shaped structures are produced by light-driven ablation in very different contexts. Penitentes 1-4 m high are common on Andean glaciers, where their formation changes glacier dynamics and hydrology. Laser ablation can produce cones 10-100 microns high with a variety of proposed applications in materials science. We report the first laboratory generation of centimeter-scale snow and ice penitentes. Systematically varying conditions allows identification of the essential parameters controlling the formation of ablation structures. We demonstrate that penitente initiation and coarsening requires cold temperatures, so that ablation leads to sublimation rather than melting. Once penitentes have formed, further growth of height can occur by melting. The penitentes intially appear as small structures (3 mm high) and grow by coarsening to 1-5 cm high. Our results are an important step towards understanding and controlling ablation morphologies.

  5. Photophoresis boosts giant planet formation

    CERN Document Server

    Teiser, Jens

    2013-01-01

    In the core accretion model of giant planet formation, a solid protoplanetary core begins to accrete gas directly from the nebula when its mass reaches about 5 earth masses. The protoplanet has at most a few million years to reach runaway gas accretion, as young stars lose their gas disks after 10 million years at the latest. Yet gas accretion also brings small dust grains entrained in the gas into the planetary atmosphere. Dust accretion creates an optically thick protoplanetary atmosphere that cannot efficiently radiate away the kinetic energy deposited by incoming planetesimals. A dust-rich atmosphere severely slows down atmospheric cooling, contraction, and inflow of new gas, in contradiction to the observed timescales of planet formation. Here we show that photophoresis is a strong mechanism for pushing dust out of the planetary atmosphere due to the momentum exchange between gas and dust grains. The thermal radiation from the heated inner atmosphere and core is sufficient to levitate dust grains and to ...

  6. Singularities formation, structure, and propagation

    CERN Document Server

    Eggers, J

    2015-01-01

    Many key phenomena in physics and engineering are described as singularities in the solutions to the differential equations describing them. Examples covered thoroughly in this book include the formation of drops and bubbles, the propagation of a crack and the formation of a shock in a gas. Aimed at a broad audience, this book provides the mathematical tools for understanding singularities and explains the many common features in their mathematical structure. Part I introduces the main concepts and techniques, using the most elementary mathematics possible so that it can be followed by readers with only a general background in differential equations. Parts II and III require more specialised methods of partial differential equations, complex analysis and asymptotic techniques. The book may be used for advanced fluid mechanics courses and as a complement to a general course on applied partial differential equations.

  7. New Paradigms For Asteroid Formation

    CERN Document Server

    Johansen, Anders; Cuzzi, Jeffrey N; Morbidelli, Alessandro; Gounelle, Matthieu

    2015-01-01

    Asteroids and meteorites provide key evidence on the formation of planetesimals in the Solar System. Asteroids are traditionally thought to form in a bottom-up process by coagulation within a population of initially km-scale planetesimals. However, new models challenge this idea by demonstrating that asteroids of sizes from 100 to 1000 km can form directly from the gravitational collapse of small particles which have organised themselves in dense filaments and clusters in the turbulent gas. Particles concentrate passively between eddies down to the smallest scales of the turbulent gas flow and inside large-scale pressure bumps and vortices. The streaming instability causes particles to take an active role in the concentration, by piling up in dense filaments whose friction on the gas reduces the radial drift compared to that of isolated particles. In this chapter we review new paradigms for asteroid formation and compare critically against the observed properties of asteroids as well as constraints from meteo...

  8. Complexity of Formation in Holography

    CERN Document Server

    Chapman, Shira; Myers, Robert C

    2016-01-01

    It was recently conjectured that the quantum complexity of a holographic boundary state can be computed by evaluating the gravitational action on a bulk region known as the Wheeler-DeWitt patch. We apply this complexity=action duality to evaluate the `complexity of formation' (arXiv:1509.07876, arXiv:1512.04993), i.e., the additional complexity arising in preparing the entangled thermofield double state with two copies of the boundary CFT compared to preparing the individual vacuum states of the two copies. We find that for boundary dimensions $d>2$, the difference in the complexities grows linearly with the thermal entropy at high temperatures. For the special case $d=2$, the complexity of formation is a fixed constant, independent of the temperature. We compare these results to those found using the complexity=volume duality.

  9. Magnetic Diffusion in Star Formation

    CERN Document Server

    Basu, Shantanu

    2010-01-01

    Magnetic diffusion plays a vital role in star formation. We trace its influence from interstellar cloud scales down to star-disk scales. On both scales, we find that magnetic diffusion can be significantly enhanced by the buildup of strong gradients in magnetic field structure. Large scale nonlinear flows can create compressed cloud layers within which ambipolar diffusion occurs rapidly. However, in the flux-freezing limit that may be applicable to photoionized molecular cloud envelopes, supersonic motions can persist for long times if driven by an externally generated magnetic field that corresponds to a subcritical mass-to-flux ratio. In the case of protostellar accretion, rapid magnetic diffusion (through Ohmic dissipation with additional support from ambipolar diffusion) near the protostar causes dramatic magnetic flux loss. By doing so, it also allows the formation of a centrifugal disk, thereby avoiding the magnetic braking catastrophe.

  10. Star Cluster Formation and Feedback

    CERN Document Server

    Krumholz, Mark R; Arce, Hector G; Dale, James E; Gutermuth, Robert; Klein, Richard I; Li, Zhi-Yun; Nakamura, Fumitaka; Zhang, Qizhou

    2014-01-01

    Stars do not generally form in isolation. Instead, they form in clusters, and in these clustered environments newborn stars can have profound effects on one another and on their parent gas clouds. Feedback from clustered stars is almost certainly responsible for a number of otherwise puzzling facts about star formation: that it is an inefficient process that proceeds slowly when averaged over galactic scales; that most stars disperse from their birth sites and dissolve into the galactic field over timescales $\\ll 1$ Gyr; and that newborn stars follow an initial mass function (IMF) with a distinct peak in the range $0.1 - 1$ $M_\\odot$, rather than an IMF dominated by brown dwarfs. In this review we summarize current observational constraints and theoretical models for the complex interplay between clustered star formation and feedback.

  11. Othering, identity formation and agency

    Directory of Open Access Journals (Sweden)

    Sune Qvotrup Jensen

    2011-10-01

    Full Text Available The article examines the potentials of the concept of othering to describe identity formation among ethnic minorities. First, it outlines the history of the concept, its contemporary use, as well as some criticisms. Then it is argued that young ethnic minority men in Denmark are subject to intersectional othering, which contains elements of exoticist fascination of the other. On the basis of ethnographic material, it is analysed how young marginalized ethnic minority men react to othering. Two types of reactions are illustrated: 1 capitalization on being positioned as the other, and 2 refusing to occupy the position of the other by disidentification and claims to normality. Finally, it is argued that the concept of othering is well suited for understanding the power structures as well as the historic symbolic meanings conditioning such identity formation, but problematic in terms of agency.

  12. Restucturing the Project Work Format

    DEFF Research Database (Denmark)

    Dupont, Søren

    2015-01-01

    The chapter is based on an evaluation of a pedagogical experiment at Roskilde University, the Antology Experiment. The objective of the experiment was to develop and expand the framework for project work through the production of anthologies compiled collectively by a number of project groups....... The novel aspects of the Anthology Experiment were most notably its magnitude and complexity. In this experiment the groups were totalling some 50 students who were working together. The experiment used a well-known publishing format from research, namely the anthology form, which usually focuses....... The organization was complex, the written product changed from project to article format, the students had to concentrate on working in their own project group as well as in the so-called clusters, and the form of exam was radically changed...

  13. Formation of Supermassive Black Holes

    CERN Document Server

    Volonteri, Marta

    2010-01-01

    Evidence shows that massive black holes reside in most local galaxies. Studies have also established a number of relations between the MBH mass and properties of the host galaxy such as bulge mass and velocity dispersion. These results suggest that central MBHs, while much less massive than the host (~ 0.1%), are linked to the evolution of galactic structure. In hierarchical cosmologies, a single big galaxy today can be traced back to the stage when it was split up in hundreds of smaller components. Did MBH seeds form with the same efficiency in small proto-galaxies, or did their formation had to await the buildup of substantial galaxies with deeper potential wells? I briefly review here some of the physical processes that are conducive to the evolution of the massive black hole population. I will discuss black hole formation processes for `seed' black holes that are likely to place at early cosmic epochs, and possible observational tests of these scenarios.

  14. Cophasing the Planet Formation Imager

    CERN Document Server

    Petrov, Romain G; Elhalkouj, Thami; Monnier, John; Ireland, Michael; Kraus, Stefan

    2016-01-01

    The Planet Formation Imager (PFI) is a project for a very large optical interferometer intended to obtain images of the planet formation process at scales as small as the Hill sphere of giant exoplanets. Its main science instruments will work in the thermal infrared but it will be cophased in the near infrared, where it requires also some capacity for scientific imaging. PFI imaging and resolution specifications imply an array of 12 to 20 apertures and baselines up to a few kilometers cophased at near infrared coherent magnitudes as large as 10. This paper discusses various cophasing architectures and the corresponding minimum diameter of individual apertures, which is the dominant element of PFI cost estimates. From a global analysis of the possible combinations of pairwise fringe sensors, we show that conventional approaches used in current interferometers imply the use of prohibitively large telescopes and we indicate the innovative strategies that would allow building PFI with affordable apertures smaller...

  15. Shock Formation in Lovelock Theories

    CERN Document Server

    Reall, Harvey S; Way, Benson

    2014-01-01

    We argue that Lovelock theories of gravity suffer from shock formation, unlike General Relativity. We consider the propagation of (i) a discontinuity in curvature, and (ii) weak, high frequency, gravitational waves. Such disturbances propagate along characteristic hypersurfaces of a "background" spacetime and their amplitude is governed by a transport equation. In GR the transport equation is linear. In Lovelock theories, it is nonlinear and its solutions can blow up, corresponding to the formation of a shock. We show that this effect is absent in some simple cases e.g. a flat background spacetime, and demonstrate its presence for a plane wave background. We comment on weak cosmic censorship, the evolution of shocks, and the nonlinear stability of Minkowski spacetime, in Lovelock theories.

  16. Biofilm formation on abiotic surfaces

    DEFF Research Database (Denmark)

    Tang, Lone

    2011-01-01

    Bacteria can attach to any surface in contact with water and proliferate into complex communities enclosed in an adhesive matrix, these communities are called biofilms. The matrix makes the biofilm difficult to remove by physical means, and bacteria in biofilm can survive treatment with many...... antibiotics, disinfectants and cleaning agents. Biofilms are therefore very difficult to eradicate, and an attractive approach to limit biofilm formation is to reduce bacterial adhesion. In this thesis it was shown that lowering the surface roughness had a greater effect on bacterial retention compared....... The ability to form biofilms, the amount of eDNA produced, and the importance of eDNA for biofilm formation or stability did not correlate and varied from strain to strain. Finally, a method was developed for immobilization of living bacteria for analysis by atomic force microscopy (AFM). AFM is used...

  17. Formation of quasiparallel Alfven solitons

    Science.gov (United States)

    Hamilton, R. L.; Kennel, C. F.; Mjolhus, E.

    1992-01-01

    The formation of quasi-parallel Alfven solitons is investigated through the inverse scattering transformation (IST) for the derivative nonlinear Schroedinger (DNLS) equation. The DNLS has a rich complement of soliton solutions consisting of a two-parameter soliton family and a one-parameter bright/dark soliton family. In this paper, the physical roles and origins of these soliton families are inferred through an analytic study of the scattering data generated by the IST for a set of initial profiles. The DNLS equation has as limiting forms the nonlinear Schroedinger (NLS), Korteweg-de-Vries (KdV) and modified Korteweg-de-Vries (MKdV) equations. Each of these limits is briefly reviewed in the physical context of quasi-parallel Alfven waves. The existence of these limiting forms serves as a natural framework for discussing the formation of Alfven solitons.

  18. Coevolutionary modeling in network formation

    KAUST Repository

    Al-Shyoukh, Ibrahim

    2014-12-03

    Network coevolution, the process of network topology evolution in feedback with dynamical processes over the network nodes, is a common feature of many engineered and natural networks. In such settings, the change in network topology occurs at a comparable time scale to nodal dynamics. Coevolutionary modeling offers the possibility to better understand how and why network structures emerge. For example, social networks can exhibit a variety of structures, ranging from almost uniform to scale-free degree distributions. While current models of network formation can reproduce these structures, coevolutionary modeling can offer a better understanding of the underlying dynamics. This paper presents an overview of recent work on coevolutionary models of network formation, with an emphasis on the following three settings: (i) dynamic flow of benefits and costs, (ii) transient link establishment costs, and (iii) latent preferential attachment.

  19. Star Formation in Satellite Galaxies

    CERN Document Server

    Funes, S J; Prada, F; Azzaro, M; Ribeiro, M B; SJ, Jose G. Funes; Gutierrez, Carlos M.; Prada, Francisco; Azzaro, Marco; Ribeiro, Marcelo B.

    2003-01-01

    The study of satellite galaxies can provide information on the merging and aggregation processes which, according to the hierarchical clustering models, form the larger spiral galaxies we observe. With the aim of testing hierarchical models of galaxy formation, we have conducted an observational program which comprises H$\\alpha$ imaging for both the parent and the satellite galaxies, taken from the compilation by Zaritsky et al. (1997) that contains 115 galaxies orbiting 69 primary isolated spiral galaxies. We have observed a subsample of 37 spiral and irregular galaxies taken from the compilation mentioned above. The aim of this study is to determine star formation properties of the sample galaxies. In this work we present the preliminary results of this program that we have carried out with the 1.8-m Vatican Telescope (VATT).

  20. THE BLACK HOLE FORMATION PROBABILITY

    International Nuclear Information System (INIS)

    A longstanding question in stellar evolution is which massive stars produce black holes (BHs) rather than neutron stars (NSs) upon death. It has been common practice to assume that a given zero-age main sequence (ZAMS) mass star (and perhaps a given metallicity) simply produces either an NS or a BH, but this fails to account for a myriad of other variables that may effect this outcome, such as spin, binarity, or even stochastic differences in the stellar structure near core collapse. We argue that instead a probabilistic description of NS versus BH formation may be better suited to account for the current uncertainties in understanding how massive stars die. We present an initial exploration of the probability that a star will make a BH as a function of its ZAMS mass, P BH(M ZAMS). Although we find that it is difficult to derive a unique P BH(M ZAMS) using current measurements of both the BH mass distribution and the degree of chemical enrichment by massive stars, we demonstrate how P BH(M ZAMS) changes with these various observational and theoretical uncertainties. We anticipate that future studies of Galactic BHs and theoretical studies of core collapse will refine P BH(M ZAMS) and argue that this framework is an important new step toward better understanding BH formation. A probabilistic description of BH formation will be useful as input for future population synthesis studies that are interested in the formation of X-ray binaries, the nature and event rate of gravitational wave sources, and answering questions about chemical enrichment

  1. Biofilm formation by Clostridium difficile

    OpenAIRE

    Dapa, Tanja; Unnikrishnan, Meera

    2013-01-01

    Clostridium difficile infection (CDI) is a major healthcare-associated disease worldwide. Recurring infections and increasing antibiotic resistance have complicated treatment of CDI. While C. difficile spores are important for transmission and persistence of CDI, other factors such as gut colonization and formation of bacterial communities in the gut may also contribute to pathogenesis and persistence, but have not been well investigated. Recently, we reported that important clinical C. diffi...

  2. Formation of artificial ionospheric ducts

    OpenAIRE

    Milikh, G. M.; Papadopoulos, K.; Shroff, H; Chang, C. L.; Wallace, T; E. V. Mishin; Parrot, Michel; Berthelier, Jean-Jacques

    2008-01-01

    International audience It is well known that strong electron heating by a powerful HF-facility can lead to the formation of electron and ion density perturbations that stretch along the magnetic field line. Those density perturbations can serve as ducts for ELF waves, both of natural and artificial origin. This paper presents the first experimental evidence of plasma modifications associated with ion outflows due to HF heating. The experiments were conducted using the HAARP heater during t...

  3. Cycling Behavior and Memory Formation

    OpenAIRE

    Gerstner, Jason R.; Lyons, Lisa C.; Wright, Kenneth P.; Loh, Dawn H; Rawashdeh, Oliver; Eckel-Mahan, Kristin L.; Roman, Gregg W.

    2009-01-01

    Circadian research has spent considerable effort in the determining clock output pathways, including identifying both physiological and behavioral processes that demonstrate significant time-of-day variation. Memory formation and consolidation represent notable processes shaped by endogenous circadian oscillators. To date, very few studies on memory mechanisms have considered potential confounding effects of time-of-day and the organism’s innate activity cycles (e.g., nocturnal, diurnal, or c...

  4. Cataract formation following vitreoretinal procedures

    OpenAIRE

    Feng H; Adelman RA

    2014-01-01

    Hao Feng, Ron A Adelman Department of Ophthalmology and Visual Science, Yale University School of Medicine, New Haven, CT, USA Purpose: To evaluate the incidence and prevalence of cataract formation, progression, and extraction in patients that underwent vitreoretinal procedures and to evaluate factors that can potentially predispose patients to postoperative cataracts.Materials and methods: The medical records of consecutive patients who underwent vitreoretinal surgery at the Yale Eye Cent...

  5. Formation of binary radio pulsars

    International Nuclear Information System (INIS)

    In the framework of the standard scenario of the evolution of massive binary stars a study is made of the formation of final binary systems in which at least one of the components is a neutron star. It is found that about every fortieth radio pulsar must be a member of a close binary system. This is confirmed by observations. Radio pulsars are not formed in wide binary systems, possibly because of the very slow rotation of the presupernova stars

  6. Neutron Stars: Formation and Structure

    OpenAIRE

    Kutschera, Marek

    1998-01-01

    A short introduction is given to astrophysics of neutron stars and to physics of dense matter in neutron stars. Observed properties of astrophysical objects containing neutron stars are discussed. Current scenarios regarding formation and evolution of neutron stars in those objects are presented. Physical principles governing the internal structure of neutron stars are considered with special emphasis on the possible spin ordering in the neutron star matter.

  7. UNION FORMATION IN FRAGILE FAMILIES*

    OpenAIRE

    Carlson, Marcia; McLanahan, Sara; England, Paula

    2004-01-01

    In this paper, we use data from a new longitudinal survey—the Fragile Families and Child Wellbeing Study—to examine union formation among unmarried parents who have just had a child together. We use multinomial logistic regression to estimate the effects of economic, cultural/interpersonal, and other factors on whether (relative to having no romantic relationship) parents are romantically involved living apart, cohabiting, or married to each other about one year after the child’s birth. Net o...

  8. Memory Formation Shaped by Astroglia

    OpenAIRE

    Zorec, Robert; Horvat, Anemari; Vardjan, Nina; VERKHRATSKY, ALEXEI

    2015-01-01

    Astrocytes, the most heterogeneous glial cells in the central nervous system (CNS), execute a multitude of homeostatic functions and contribute to memory formation. Consolidation of synaptic and systemic memory is a prolonged process and hours are required to form long-term memory. In the past, neurons or their parts have been considered to be the exclusive cellular sites of these processes, however, it has now become evident that astrocytes provide an important and essential contribution to ...

  9. Hydrodynamics of catheter biofilm formation

    CERN Document Server

    Sotolongo-Costa, Oscar; Rodriguez-Perez, Daniel; Martinez-Escobar, Sergio; Fernandez-Barbero, Antonio

    2009-01-01

    A hydrodynamic model is proposed to describe one of the most critical problems in intensive medical care units: the formation of biofilms inside central venous catheters. The incorporation of approximate solutions for the flow-limited diffusion equation leads to the conclusion that biofilms grow on the internal catheter wall due to the counter-stream diffusion of blood through a very thin layer close to the wall. This biological deposition is the first necessary step for the subsequent bacteria colonization.

  10. Non cooperative Stackelberg network formation

    Directory of Open Access Journals (Sweden)

    Juan M.C Larrosa

    2014-12-01

    Full Text Available Non-cooperative network formation games in industrial organizations analyze how firms create links. We assume that links portray cost-reducing information and that access to this information is not reciprocal. We study the consequences in terms of profits if one firm can move first in establishing a link. A classic model of exogenous Stackelberg leadership is developed and first-mover advantage is observed.

  11. Formation of Cosmic Dust Bunnies

    OpenAIRE

    Matthews, Lorin S.; Hayes, Ryan L.; Freed, Michael S.; Hyde, Truell W.

    2007-01-01

    Planetary formation is an efficient process now thought to take place on a relatively short astronomical time scale. Recent observations have shown that the dust surrounding a protostar emits more efficiently at longer wavelengths as the protoplanetary disk evolves, suggesting that the dust particles are coagulating into fluffy aggregates, "much as dust bunnies form under a bed." One poorly understood problem in this coagulation process is the manner in which micron-sized, charged grains form...

  12. Simulation of primordial object formation

    CERN Document Server

    Fuller, T M; Fuller, Todd M.

    2000-01-01

    We have included the chemical rate network responsible for the formation ofmolecular Hydrogen in the N-body hydrodynamic code, Hydra, in order to studythe formation of the first cosmological at redshifts between 10 and 50. We havetested our implementation of the chemical and cooling processes by comparingN-body top hat simulations with theoretical predictions from a semi-analyticmodel and found them to be in good agreement. We find that post-virializationproperties are insensitive to the initial abundance of molecular hydrogen. Ourmain objective was to determine the minimum mass ($M_{SG}(z)$) of perturbationsthat could become self gravitating (a prerequisite for star formation), and theredshift at which this occurred. We have developed a robust indicator fordetecting the presence of a self-gravitating cloud in our simulations and findthat we can do so with a baryonic particle mass-resolution of 40 solar masses.We have performed cosmological simulations of primordial objects and find thatthe object's mass and ...

  13. Illusory contour formation survives crowding.

    Science.gov (United States)

    Lau, Jonathan Siu Fung; Cheung, Sing-Hang

    2012-06-12

    Flanked objects are difficult to identify using peripheral vision due to visual crowding, which limits conscious access to target identity. Nonetheless, certain types of visual information have been shown to survive crowding. Such resilience to crowding provides valuable information about the underlying neural mechanism of crowding. Here we ask whether illusory contour formation survives crowding of the inducers. We manipulated the presence of illusory contours through the (mis)alignment of the four inducers of a Kanizsa square. In the inducer-aligned condition, the observers judged the perceived shape (thin vs. fat) of the illusory Kanizsa square, manipulated by small rotations of the inducers. In the inducer-misaligned condition, three of the four inducers (all except the upper-left) were rotated 90°. The observers judged the orientation of the upper-left inducer. Crowding of the inducers worsened observers' performance significantly only in the inducer-misaligned condition. Our findings suggest that information for illusory contour formation survives crowding of the inducers. Crowding happens at a stage where the low-level featural information is integrated for inducer orientation discrimination, but not at a stage where the same information is used for illusory contour formation.

  14. Modeling of Dynamic FRC Formation

    Science.gov (United States)

    Mok, Yung; Barnes, Dan; Dettrick, Sean

    2010-11-01

    We have developed a 2-D resistive MHD code, Lamy Ridge, to simulate the entire FRC formation process in Tri Alpha's C2 device, including initial formation, translation, merging and settling into equilibrium. Two FRC's can be created simultaneously, and then translated toward each other so that they merge into a single FRC. The code couples the external circuits around the formation tubes to the partially ionized plasma inside. Plasma and neutral gas are treated as two fluids. Dynamic and energetic equations, which take into account ionization and charge exchange, are solved in a time advance manner. The geometric shape of the vessel is specified by a set of inputs that defines the boundaries, which are handled by a cut-cell algorithm in the code. Multiple external circuits and field coils can be easily added, removed or relocated through individual inputs. The design of the code is modular and flexible so that it can be applied to future devices. The results of the code are in reasonable agreement with experimental measurements on the C2 device.

  15. Pattern formation in optical resonators

    International Nuclear Information System (INIS)

    We review pattern formation in optical resonators. The emphasis is on 'particle-like' structures such as vortices or spatial solitons. On the one hand, similarities impose themselves with other fields of physics (condensed matter, phase transitions, particle physics, fluds/super fluids). On the other hand the feedback is led by the resonator mirrors to bi- and multi-stability of the spatial field structure, which is the basic ingredient for optical information processing. The spatial dimension or the 'parallelism' is the strength of optics compared to electronics (and will have to be employed to fully use the advantages optics offers in information processing). But even in the 'serial' processing tasks of telecoms (e.g. information buffering) spatial resonator solitons can do better than the schemes proposed so far-including 'slow light'. Pattern formation in optical resonators will likely be the key to brain-like information processing like cognition, learning and association; to complement the precise but limited algorithmic capabilities of electronic processing. But even in the short term it will be useful for solving serial optical processing problems. The prospects for technical uses of pattern formation in resonators are one motivation for this research. The fundamental similarities with other fields of physics, on the other hand, inspire transfer of concepts between fields; something that has always proven fruitful for gaining deeper insights or for solving technical problems

  16. Star Formation in Satellite Galaxies

    CERN Document Server

    Gutíerrez, C M; Funes, J G; Ribeiro, M B

    2006-01-01

    We present narrow-band observations of the H$\\alpha$ emission in a sample of 31 satellite orbiting isolated giant spiral galaxies. The sample studied spans the range $-19formation rates are 0.68 and 3.66 M$_\\sun$ yr$^{-1}$ respectively. Maps of the spatial distribution of ionized gas are presented. The star-forming regions show a rich structure in which frequently discrete complexes are imposed over more diffuse structures. In general, the current star formation rates are smaller that the mean values in the past obtained from the current stellar content; this probably indicates a declining rhythm with time in the generation of new stars. However, the reserve of gas is enough to continue fueling the current levels of star formation activity for at least another Hubble time. Four of the o...

  17. Hypothesis Formation, Paradigms, and Openness

    Directory of Open Access Journals (Sweden)

    Conrad P. Pritscher

    2008-01-01

    Full Text Available A part of hypothesis formation, while necessary for scientific investigation, is beyond direct observation. Powerful hypothesis formation is more than logical and is facilitated by mind­opening. As Percy Bridgeman, Nobel laureate, said, science is: “Nothing more than doing one's damnedest with one's mind, no holds barred.” This paper suggests more open schooling helps generate more open hypothesizing which helps one do one's damnedest with one's mind. It is hypothesized that a more open process of hypothesis formation may help schools and society forge new ways of living and learning so that more people more often can do their damnedest with their mind. This writing does not offer a new paradigm but rather attempts to elaborate on the notion that new paradigms are difficult to form without openness to what was previously quasi­unthinkable. More on these topics and issues is included in the author's Reopening Einstein's Thought: About What Can't Be Learned From Textbooks ­­to be published by Sense Publishers in June 2008.

  18. Kinetic competition during glass formation

    Energy Technology Data Exchange (ETDEWEB)

    Perepezko, J.H., E-mail: perepezk@engr.wisc.edu [University of Wisconsin-Madison, Department of Materials Science and Engineering, 1509 University Ave., Madison, WI 53706 (United States); Santhaweesuk, C.; Wang, J.Q. [University of Wisconsin-Madison, Department of Materials Science and Engineering, 1509 University Ave., Madison, WI 53706 (United States); Imhoff, S.D. [Los Alamos National Laboratory, Materials Science and Technology Div., Los Alamos, NM 87545 (United States)

    2014-12-05

    Highlights: • The kinetics of glass formation has been elucidated in an Fe and Au-base alloy. • A critical cooling rate range should be considered for glass formation. • Wedge casting, calorimetry and upquenching data are used to model TTT curves. - Abstract: For vitrification of an alloy melt during cooling there is a kinetic competition with the nucleation and growth of metastable and stable crystalline phases. Many of the measures of glass forming ability (GFA) attempt to capture some of the features of the kinetic competition, but the GFA metrics are static measures and the kinetic processes are dynamic in nature. In fact, the critical cooling rate for glass formation should be viewed in terms of a critical cooling rate range to acknowledge the stochastic nature of crystal nucleation behavior. Direct measurements of the critical cooling rate range confirm this behavior and also provide useful input for kinetics analysis. Usually kinetics analyses are based upon crystallization behavior that is measured either isothermally or upon heating to temperatures near the crystallization onset, T{sub x} and the results are extrapolated to much higher temperatures. This practice is based upon a number of assumptions about transport behavior in the undercooled liquid. With rapid up-quenching of amorphous samples, the high temperature crystallization behavior can be measured and used to refine the kinetics analysis and provide useful insight on the kinetic competition and glass forming ability.

  19. NSDF: Neuroscience Simulation Data Format.

    Science.gov (United States)

    Ray, Subhasis; Chintaluri, Chaitanya; Bhalla, Upinder S; Wójcik, Daniel K

    2016-04-01

    Data interchange is emerging as an essential aspect of modern neuroscience. In the areas of computational neuroscience and systems biology there are multiple model definition formats, which have contributed strongly to the development of an ecosystem of simulation and analysis tools. Here we report the development of the Neuroscience Simulation Data Format (NSDF) which extends this ecosystem to the data generated in simulations. NSDF is designed to store simulator output across scales: from multiscale chemical and electrical signaling models, to detailed single-neuron and network models, to abstract neural nets. It is self-documenting, efficient, modular, and scalable, both in terms of novel data types and in terms of data volume. NSDF is simulator-independent, and can be used by a range of standalone analysis and visualization tools. It may also be used to store variety of experimental data. NSDF is based on the widely used HDF5 (Hierarchical Data Format 5) specification and is open, platform-independent, and portable. PMID:26585711

  20. Theory of Remote Image Formation

    Science.gov (United States)

    Blahut, Richard E.

    2004-11-01

    In many applications, images, such as ultrasonic or X-ray signals, are recorded and then analyzed with digital or optical processors in order to extract information. Such processing requires the development of algorithms of great precision and sophistication. This book presents a unified treatment of the mathematical methods that underpin the various algorithms used in remote image formation. The author begins with a review of transform and filter theory. He then discusses two- and three-dimensional Fourier transform theory, the ambiguity function, image construction and reconstruction, tomography, baseband surveillance systems, and passive systems (where the signal source might be an earthquake or a galaxy). Information-theoretic methods in image formation are also covered, as are phase errors and phase noise. Throughout the book, practical applications illustrate theoretical concepts, and there are many homework problems. The book is aimed at graduate students of electrical engineering and computer science, and practitioners in industry. Presents a unified treatment of the mathematical methods that underpin the algorithms used in remote image formation Illustrates theoretical concepts with reference to practical applications Provides insights into the design parameters of real systems

  1. Kinetic competition during glass formation

    International Nuclear Information System (INIS)

    Highlights: • The kinetics of glass formation has been elucidated in an Fe and Au-base alloy. • A critical cooling rate range should be considered for glass formation. • Wedge casting, calorimetry and upquenching data are used to model TTT curves. - Abstract: For vitrification of an alloy melt during cooling there is a kinetic competition with the nucleation and growth of metastable and stable crystalline phases. Many of the measures of glass forming ability (GFA) attempt to capture some of the features of the kinetic competition, but the GFA metrics are static measures and the kinetic processes are dynamic in nature. In fact, the critical cooling rate for glass formation should be viewed in terms of a critical cooling rate range to acknowledge the stochastic nature of crystal nucleation behavior. Direct measurements of the critical cooling rate range confirm this behavior and also provide useful input for kinetics analysis. Usually kinetics analyses are based upon crystallization behavior that is measured either isothermally or upon heating to temperatures near the crystallization onset, Tx and the results are extrapolated to much higher temperatures. This practice is based upon a number of assumptions about transport behavior in the undercooled liquid. With rapid up-quenching of amorphous samples, the high temperature crystallization behavior can be measured and used to refine the kinetics analysis and provide useful insight on the kinetic competition and glass forming ability

  2. Dioxin formation from waste incineration.

    Science.gov (United States)

    Shibamoto, Takayuki; Yasuhara, Akio; Katami, Takeo

    2007-01-01

    There has been great concern about dioxins-polychlorinated dibenzo dioxins (PCDDs), polychlorinated dibenzo furans (PCDFs), and polychlorinated biphenyls (PCBs)-causing contamination in the environment because the adverse effects of these chemicals on human health have been known for many years. Possible dioxin-contamination has received much attention recently not only by environmental scientists but also by the public, because dioxins are known to be formed during the combustion of industrial and domestic wastes and to escape into the environment via exhaust gases from incinerators. Consequently, there is a pressing need to investigate the formation mechanisms or reaction pathways of these chlorinated chemicals to be able to devise ways to reduce their environmental contamination. A well-controlled small-scale incinerator was used for the experiments in the core references of this review. These articles report the investigation of dioxin formation from the combustion of various waste-simulated samples, including different kinds of paper, various kinds of wood, fallen leaves, food samples, polyethylene (PE), polystyrene (PS), polyvinyl chloride (PVC), polyvinylidene chloride, polyethylene tetraphthalate (PET), and various kinds of plastic products. These samples were also incinerated with inorganic chlorides (NaCl, KCl, CuCI2, MgCl2, MnCl2, FeCl2, CoCl2, fly ash, and seawater) or organic chlorides (PVC, chlordane, and pentachlorophenol) to investigate the role of chlorine content and/or the presence of different metals in dioxin formation. Some samples, such as newspapers, were burned after they were impregnated with NaCl or PVC, as well as being cocombusted with chlorides. The roles of incineration conditions, including chamber temperatures, O2 concentrations, and CO concentrations, in dioxin formation were also investigated. Dioxins (PCDDs, PCDFs, and coplanar-PCBs) formed in the exhaust gases from a controlled small-scale incinerator, where experimental waste

  3. Core formation in silicate bodies

    Science.gov (United States)

    Nimmo, F.; O'Brien, D. P.; Kleine, T.

    2008-12-01

    Differentiation of a body into a metallic core and silicate mantle occurs most efficiently if temperatures are high enough to allow at least the metal to melt [1], and is enhanced if matrix deformation occurs [2]. Elevated temperatures may occur due to either decay of short-lived radio-isotopes, or gravitational energy release during accretion [3]. For bodies smaller than the Moon, core formation happens primarily due to radioactive decay. The Hf-W isotopic system may be used to date core formation; cores in some iron meteorites and the eucrite parent body (probably Vesta) formed within 1 My and 1-4~My of solar system formation, respectively [4]. These formation times are early enough to ensure widespread melting and differentiation by 26Al decay. Incorporation of Fe60 into the core, together with rapid early mantle solidification and cooling, may have driven early dynamo activity on some bodies [5]. Iron meteorites are typically depleted in sulphur relative to chondrites, for unknown reasons [6]. This depletion contrasts with the apparently higher sulphur contents of cores in larger planetary bodies, such as Mars [7], and also has a significant effect on the timing of core solidification. For bodies of Moon-size and larger, gravitational energy released during accretion is probably the primary cause of core formation [3]. The final stages of accretion involve large, stochastic collisions [8] between objects which are already differentiated. During each collision, the metallic cores of the colliding objects merge on timescales of a few hours [9]. Each collision will reset the Hf-W isotopic signature of both mantle and core, depending on the degree to which the impactor core re-equilibrates with the mantle of the target [10]. The re-equilibration efficiency depends mainly on the degree to which the impactor emulsifies [11], which is very uncertain. Results from N-body simulations [8,12] suggest that significant degrees of re- equilibration are required [4,10]. Re

  4. MHD turbulence, cloud formation and star formation in the ISM

    CERN Document Server

    Vázquez-Semadeni, E; Pouquet, A

    1996-01-01

    We discuss the role of turbulence in cloud and star formation, as observed in numerical simulations of the interstellar medium. Turbulent compression at the interfaces of colliding gas streams is responsible for the formation of intermediate (\\simlt 100 pc) and small clouds (a few tens of pc), although the smallest clouds can also form from fragmentation of expanding shells around stellar heating centers. The largest cloud complexes (several hundred pc) seem to form by slow, gravitational instability-driven merging of individual clouds, which can actually be described as a large-scale tendency towards homogenization of the flow due to gravity rather than cloud collisions. These mechanisms operate as well in the presence of a magnetic field and rotation, although slight variations on the compressibility and cloud morphology are present which depend on the strength and topology of the field. In summary, the role of turbulence in the life-cycle of clouds appears to be twofold: small-scale modes contribute to clo...

  5. Package Formats for Preserved Digital Material

    DEFF Research Database (Denmark)

    Zierau, Eld

    2012-01-01

    This paper presents an investigation of the best suitable package formats for long term digital preservation. The choice of a package format for preservation is crucial for future access, thus a thorough analysis of choice is important. The investigation presented here covers setting up...... requirements for package formats used for long term preserved digital material, and using these requirements as the basis for analysing a range of package formats. The result of the concrete investigation is that the WARC format is the package format best suited for the listed requirements. Fulfilling...

  6. DIKE FORMATION WITH SUBMERGED VANE

    Institute of Scientific and Technical Information of China (English)

    Umesh P.GUPTA; C.S.P.OJHA; Nayan SHARMA

    2006-01-01

    Submerged vanes are submerged foils constructed in a river at an angle of attack to induce horizontal circulation in the downstream flow. The initial height of vanes is 0.2 - 0.4 times the local water depth (d) at the design stage. Its length expressed as a multiple of the height to length ratio (H/L) normally is 0.25 to 0.5. With the use of a submerged vane in straight channels, dikes (heaps of sediment) were formed downstream. At an optimal angle of attack of 40o and at a Froude number of 0.25, the formation of the dike starts at some distance from the trailing edge of the rectangular and trapezoidal submerged vanes with a collar. A significant scour hole results at the trailing edge of a vane with a collar. A typical dike formed along the vane on the suction side with a symmetric bell-shaped profile. The dike formation phenomenon triggered by a vane close to the bank-line at a flow with a relatively higher Froude number, such as 0.25, does not seem to follow a straight alignment, but has a sort of curvilinear shape bent towards the suction side. The dike formation process for a flow with a smaller Froude number, such as 0.13, is observed to not be appreciable. With the same installation height of H, a vane without a collar was dislodged by the flow at a Froude number of 0.25, whereas it was stable at a Froude number of 0.13.

  7. Massive neutrinos and galaxy formation

    CERN Document Server

    Ma Chung Pei

    1994-01-01

    We report the most recent results from high-resolution numerical simulations of structure formation in two flat cold+hot dark matter models with neutrino mass densities \\onu=0.2 and 0.3. We find that structure forms too late in all CDM+HDM models with \\onu>0.2 to account for the amount of dense neutral gas in high-redshift damped Lyman-\\alpha systems. The \\onu=0.2 model at z\\approx0 provides a better match to observations than the pure CDM model.

  8. Branch formation during organ development

    Science.gov (United States)

    Gjorevski, Nikolce; Nelson, Celeste M.

    2010-01-01

    Invertebrates and vertebrates use branching morphogenesis to build epithelial trees to maximize the surface area of organs within a given volume. Several molecular regulators of branching have recently been discovered, a number of which are conserved across different organs and species. Signals that control branching at the cellular and tissue levels are also starting to emerge, and are rapidly unveiling the physical nature of branch development. Here we discuss the molecular, cellular and physical processes that govern branch formation and highlight the major outstanding questions in the field. PMID:20890968

  9. Biofilm formation and microbial corrosion

    Energy Technology Data Exchange (ETDEWEB)

    Goldstein, R.; Porcella, D.

    1992-07-01

    Biofilms-colonies of microorganisms growing on surfaces - can greatly accelerate the corrosion rates of metals and alloys in utility water systems. Fundamental EPRI research is showing how mechanisms of biofilm formation, interactions between bacterial species, and metabolic activities control such biofilm properties as corrosive potential This research is identifying methods to control biofilm development and prevent microbially influenced corrosion. The results should also apply to the control of other processes involving biological consortia, including the bioremediation of contaminated groundwater and soil and the biodesulfurization of coal.

  10. Formation flight astronomical survey telescope

    Science.gov (United States)

    Tsunemi, Hiroshi

    2012-03-01

    Formation Flight Astronomical Survey Telescope (FFAST) is a project for hard X-ray observation. It consists of two small satellites; one (telescope satellite) has a super mirror covering the energy range up to 80 keV while the other (detector satellite) has an scintillator deposited CCD (SDCCD) having good spatial resolution and high efficiency up to 100 keV. Two satellites will be put into individual Kepler orbits forming an X-ray telescope with a focal length of 20 m. They will be not in pointing mode but in survey mode to cover a large sky region.

  11. Adsorption-induced step formation

    DEFF Research Database (Denmark)

    Thostrup, P.; Christoffersen, Ebbe; Lorensen, Henrik Qvist;

    2001-01-01

    Through an interplay between density functional calculations, Monte Carlo simulations and scanning tunneling microscopy experiments, we show that an intermediate coverage of CO on the Pt(110) surface gives rise to a new rough equilibrium structure with more than 50% step atoms. CO is shown to bind...... so strongly to low-coordinated Pt atoms that it can break Pt-Pt bonds and spontaneously form steps on the surface. It is argued that adsorption-induced step formation may be a general effect, in particular at high gas pressures and temperatures....

  12. XML Format for SESAME and LEOS

    Energy Technology Data Exchange (ETDEWEB)

    Durrenberger, J K; Neely, J R; Sterne, P A

    2009-04-29

    The objective of this document is to describe the XML format used by LLNL and LANL to represent the equation-of-state and related material information in the LEOS and SESAME data libraries. The primary purpose of this document is to describe a specific XML format for representing EOS data that is tailored to the nature of the underlying data and is amenable to conversion to both legacy SESAME and LEOS binary formats. The secondary purpose is to describe an XML format that lends itself to a 'natural' representation in a binary file format of the SESAME, pdb or hdf5 form so that this format and related tools can be used for the rapid and efficient development and implementation of prototype data structures. This document describes the XML format only. A working knowledge of LEOS and SESAME formats is assumed.

  13. The Current Status of Galaxy Formation

    OpenAIRE

    Silk, Joe; Mamon, Gary A.

    2012-01-01

    Understanding galaxy formation is one of the most pressing issues in cosmology. We review the current status of galaxy formation from both an observational and a theoretical perspective, and summarise the prospects for future advances.

  14. Multilevel Modulation formats for Optical Communication

    DEFF Research Database (Denmark)

    Jensen, Jesper Bevensee

    2008-01-01

    This thesis studies the use of multilevel modulation formats for optical communication systems. Multilevel modulation is an attractive method of increasing the spectral efficiency of optical communication systems. Various modulation formats employing phase modulation, amplitude modulation...

  15. SAR polar format implementation with MATLAB.

    Energy Technology Data Exchange (ETDEWEB)

    Martin, Grant D.; Doerry, Armin Walter

    2005-11-01

    Traditional polar format image formation for Synthetic Aperture Radar (SAR) requires a large amount of processing power and memory in order to accomplish in real-time. These requirements can thus eliminate the possible usage of interpreted language environments such as MATLAB. However, with trapezoidal aperture phase history collection and changes to the traditional polar format algorithm, certain optimizations make MATLAB a possible tool for image formation. Thus, this document's purpose is two-fold. The first outlines a change to the existing Polar Format MATLAB implementation utilizing the Chirp Z-Transform that improves performance and memory usage achieving near realtime results for smaller apertures. The second is the addition of two new possible image formation options that perform a more traditional interpolation style image formation. These options allow the continued exploration of possible interpolation methods for image formation and some preliminary results comparing image quality are given.

  16. On the modelling of river delta formation

    NARCIS (Netherlands)

    Geleynse, N.

    2013-01-01

    This thesis presents approaches to the modelling of river delta formation. In particular, it provides results of numerical stratigraphic-morphodynamic modelling of river delta formation under various environmental forcings.

  17. Molecular mechanism of bone formation and regeneration

    Institute of Scientific and Technical Information of China (English)

    Akira Yamaguchi

    2008-01-01

    @@ Bone formation and regeneration are mediated by the coordinate action of various factors. Among these, bone morphogenetic protein (BMP) and runt-related gene 2 (Runx2) play crucial roles in bone formation.

  18. FORMATE-BASED FLUIDS: FORMULATION AND APPLICATION

    Directory of Open Access Journals (Sweden)

    Nediljka Gaurina-Međimurec

    2008-12-01

    Full Text Available Formate-based fluids has been successfully used in over hunders HPHT well operations since they introduced in field practice. They have many advantages when compared with conventional HPHT drilling and completion fluids such as: minimal formation damage, maintenance of additve properties at high temperatures, reduced hydraulic flow resistance, low potential for differential sticking, naturally lubricating, very low corrosion rates, biodegradable and pose little risk to the environment etc. Formate-based fluids can be applied during deep slim hole drilling, shale drilling, reservoir drilling, salt and gas hydrate formations drilling. The laboratory research was carried out to evaluate the rheological behavior of formate-based fluids as a function of temperature. Formate-based fluids were formulated using potassium formate brine, xanthan polymer, PAC, starch and calcium carbonate. Experimental results show that potassium formate improves the thermal stability of polymers.

  19. Choosing to write the paper format thesis.

    Science.gov (United States)

    Morris, H M; Tipples, G

    1998-04-01

    Graduate students today may be faced with the option of writing either a traditional format thesis or a paper format thesis. In contrast to the traditional format in which the text body consists of four or five chapters, the body of the paper format thesis can be comprised of an introductory chapter, two or more papers written as publishable manuscripts, and a conclusion. In this article, an overview of the paper format thesis is presented and contrasted with the traditional format thesis. The description of the paper format thesis is followed by its advantages and disadvantages for writers and readers. It is by weighing all possible pros and cons, as well as considering one's individual situation, that the graduate student will be able to decide which format of thesis to write.

  20. Enamel formation and amelogenesis imperfecta.

    Science.gov (United States)

    Hu, Jan C-C; Chun, Yong-Hee P; Al Hazzazzi, Turki; Simmer, James P

    2007-01-01

    Dental enamel is the epithelial-derived hard tissue covering the crowns of teeth. It is the most highly mineralized and hardest tissue in the body. Dental enamel is acellular and has no physiological means of repair outside of the protective and remineralization potential provided by saliva. Enamel is comprised of highly organized hydroxyapatite crystals that form in a defined extracellular space, the contents of which are supplied and regulated by ameloblasts. The entire process is under genetic instruction. The genetic control of amelogenesis is poorly understood, but requires the activities of multiple components that are uniquely important for dental enamel formation. Amelogenesis imperfecta (AI) is a collective designation for the variety of inherited conditions displaying isolated enamel malformations, but the designation is also used to indicate the presence of an enamel phenotype in syndromes. Recently, genetic studies have demonstrated the importance of genes encoding enamel matrix proteins in the etiology of isolated AI. Here we review the essential elements of dental enamel formation and the results of genetic analyses that have identified disease-causing mutations in genes encoding enamel matrix proteins. In addition, we provide a fresh perspective on the roles matrix proteins play in catalyzing the biomineralization of dental enamel.

  1. Simulations for terrestrial planets formation

    Institute of Scientific and Technical Information of China (English)

    ZHANG Niu; JI JiangHui

    2009-01-01

    In this paper, the formation of terrestrial planets in the late stage of planetary formation is Investigated using the two-planet model. At that time, the protostar formed for about 3 Ma and the gas disk dissipated. In the model, the perturbations from Jupiter and Saturn are considered. Variations of the mass of outer planet, and the initial eccentricities and inclinations of embryos and planetesimals are also considered. Our results show that, terrestrial planets are formed in 50 Ma, and the accretion rate is about 60%-80%. In each simulation, 3-4 terrestrial planets are formed inside "Jupiter" with masses of 0.15-3.6 M(⊙). In the 0.5-4 AU, when the eccentricities of planetesimals are excited, planetesimals are able to accrete material from wide radial direction. The plenty of water material of the terrestrial planet in the Habitable Zone may be transferred from the farther places by this mechanism. Accretion could also happen a few times between two major planets only if the outer planet has a moderate mass and the small terrestrial planet could survive at some resonances over time scale of 108a. In one of our simulations, commensurability of the orbital periods of planets is very common. Moreover, a librating-circulating 3:2 configuration of mean motion resonance is found.

  2. Simulations for terrestrial planets formation

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    In this paper,the formation of terrestrial planets in the late stage of planetary formation is investigated using the two-planet model.At that time,the protostar formed for about 3 Ma and the gas disk dissipated.In the model,the perturbations from Jupiter and Saturn are considered.Variations of the mass of outer planet,and the initial eccentricities and inclinations of embryos and planetesimals are also considered.Our results show that,terrestrial planets are formed in 50 Ma,and the accretion rate is about 60%-80%.In each simulation,3-4 terrestrial planets are formed inside"Jupiter"with masses of 0.15 -3.6M⊕.In the 0.5-4 AU,when the eccentricities of planetesimals are excited,planetesimals are able to accrete material from wide radial direction.The plenty of water material of the terrestrial planet in the Habitable Zone may be transferred from the farther places by this mechanism.Accretion could also happen a few times between two major planets only if the outer planet has a moderate mass and the small terrestrial planet could survive at some resonances over time scale of 10 8 a.In one of our simulations,commensurability of the orbital periods of planets is very common.Moreover,a librating-circulating 3:2 configuration of mean motion resonance is found.

  3. Radical formation by heavy metals

    Energy Technology Data Exchange (ETDEWEB)

    Beuter, W.

    1982-09-01

    Certain reduced heavy metal ions can convert oxygen to a ''reactive oxygen species'' by donation of an electron. The reactive oxygen then attacks structures susceptible to oxidation, in particular unsaturated fatty acids, and peroxidizes them in a radical reaction. This process is inhibited by the presence of vitamin E and by other means. Peroxidized lipids decay forming free radicals in the process which themselves can peroxidise neighbouring lipids in a radical chain reaction. This decay is, moreover, catalysed by reduced heavy metal ions but on the other hand retarded by selenium-containing glutathione peroxidase. Radical formation by heavy metals is considerably involved in (i) the production of parenteral iron poisoning of the piglet (ii) haemolytic crisis occurring in ruminants through chronic copper poisoning (iii) the production of lead poisoning in ruminants and other animals. These types of poisonings are made worse by a deficiency of vitamin E and/or selenium. Factors which increase the bio-availability of the free heavy metal ion or reduce the redox potential thereof can aid radical formation as well as factors which lead to a reduction of the heavy metal ion e.g. cysteine, ascorbic acid or glucose.

  4. Tube Formation in Nanoscale Materials

    Directory of Open Access Journals (Sweden)

    Yan Chenglin

    2008-01-01

    Full Text Available Abstract The formation of tubular nanostructures normally requires layered, anisotropic, or pseudo-layered crystal structures, while inorganic compounds typically do not possess such structures, inorganic nanotubes thus have been a hot topic in the past decade. In this article, we review recent research activities on nanotubes fabrication and focus on three novel synthetic strategies for generating nanotubes from inorganic materials that do not have a layered structure. Specifically, thermal oxidation method based on gas–solid reaction to porous CuO nanotubes has been successfully established, semiconductor ZnS and Nb2O5nanotubes have been prepared by employing sacrificial template strategy based on liquid–solid reaction, and an in situ template method has been developed for the preparation of ZnO taper tubes through a chemical etching reaction. We have described the nanotube formation processes and illustrated the detailed key factors during their growth. The proposed mechanisms are presented for nanotube fabrication and the important pioneering studies are discussed on the rational design and fabrication of functional materials with tubular structures. It is the intention of this contribution to provide a brief account of these research activities.

  5. Characteristic Scales in Galaxy Formation

    CERN Document Server

    Dekel, A

    2004-01-01

    Recent data, e.g. from SDSS and 2dF, reveal a robust bi-modality in the distribution of galaxy properties, with a characteristic transition scale at stellar mass M_*~3x10^{10} Msun (near L_*), corresponding to virial velocity V~100 km/s. Smaller galaxies tend to be blue disks of young populations. They define a "fundamental line" of decreasing surface brightness, metallicity and velocity with decreasing M_*, which extends to the smallest dwarf galaxies. Galaxies above the critical scale are dominated by red spheroids of old populations, with roughly constant high surface brightens and metallicity, and they tend to host AGNs. A minimum in the virial M/L is obtained at the same magic scale. This bi-modality can be the combined imprint of several different physical processes. On smaller scales, disks are built by cold flows, and supernova feedback is effective in regulating star formation. On larger scales, the infalling gas is heated by a virial shock and star formation can be suppressed by AGN feedback. Anothe...

  6. The formation of flashbulb memories.

    Science.gov (United States)

    Conway, M A; Anderson, S J; Larsen, S F; Donnelly, C M; McDaniel, M A; McClelland, A G; Rawles, R E; Logie, R H

    1994-05-01

    A large group of subjects took part in a multinational test-retest study to investigate the formation of flashbulb (FB) memories for learning the news of the resignation of the British prime minister, Margaret Thatcher. Over 86% of the U.K. subjects were found to have FB memories nearly 1 year after the resignation; their memory reports were characterized by spontaneous, accurate, and full recall of event details, including minutiae. In contrast, less than 29% of the non-U.K. subjects had FB memories 1 year later; memory reports in this group were characterized by forgetting, reconstructive errors, and confabulatory responses. A causal analysis of secondary variables showed that the formation of FB memories was primarily associated with the level of importance attached to the event and level of affective response to the news. These findings lend some support to the study by R. Brown and Kulik (1977), who suggest that FB memories may constitute a class of autobiographical memories distinguished by some form of preferential encoding.

  7. The Formation of Very Massive Stars

    OpenAIRE

    Krumholz, Mark R

    2014-01-01

    In this chapter I review theoretical models for the formation of very massive stars. After a brief overview of some relevant observations, I spend the bulk of the chapter describing two possible routes to the formation of very massive stars: formation via gas accretion, and formation via collisions between smaller stars. For direct accretion, I discuss the problems of how interstellar gas may be prevented from fragmenting so that it is available for incorporation into a single very massive st...

  8. Formation of embryoid bodies using dielectrophoresis

    OpenAIRE

    Agarwal, Sneha; Sebastian, Anil; Forrester, Lesley M; Markx, Gerard H

    2012-01-01

    Embryoid body (EB) formation forms an important step in embryonic stem cell differentiation invivo. In murine embryonic stem cell (mESC) cultures EB formation is inhibited by the inclusion of leukaemic inhibitory factor (LIF) in the medium. Assembly of mESCs into aggregates by positive dielectrophoresis (DEP) in high field regions between interdigitated oppositely castellated electrodes was found to initiate EB formation. Embryoid body formation in aggregates formed with DEP occurred at a mor...

  9. Treating nahcolite containing formations and saline zones

    Energy Technology Data Exchange (ETDEWEB)

    Vinegar, Harold J

    2013-06-11

    A method for treating a nahcolite containing subsurface formation includes removing water from a saline zone in or near the formation. The removed water is heated using a steam and electricity cogeneration facility. The heated water is provided to the nahcolite containing formation. A fluid is produced from the nahcolite containing formation. The fluid includes at least some dissolved nahcolite. At least some of the fluid is provided to the saline zone.

  10. Towards the Rosetta Stone of planet formation

    OpenAIRE

    Schmidt T.O.B.; Roell T.; Raetz St.; Pribulla T.; Moualla M.; Marka C.; Kramm U.; Hohle M.; Ginski Ch.; Fiedler S.; Eisenbeiss T.; Berndt A.; Adam Ch.; Mugrauer M.; Errmann R.

    2011-01-01

    Transiting exoplanets (TEPs) observed just about 10 Myrs after formation of their host systems may serve as the Rosetta Stone for planet formation theories. They would give strong constraints on several aspects of planet formation, e.g. time-scales (planet formation would then be possible within 10 Myrs), the radius of the planet could indicate whether planets form by gravitational collapse (being larger when young) or accretion growth (being smaller when young). We present a survey, the main...

  11. Supermassive Black Holes and Galaxy Formation

    OpenAIRE

    Silk, Joseph

    2001-01-01

    The formation of supermassive black holes (SMBH) is intimately related to galaxy formation, although precisely how remains a mystery. I speculate that formation of, and feedback from, SMBH may alleviate problems that have arisen in our understanding of the cores of dark halos of galaxies.

  12. Formation of tax culture in Russia

    Directory of Open Access Journals (Sweden)

    Halikova Je.A.

    2014-11-01

    Full Text Available This article deals with the mechanism of the formation of tax culture in Russia, moral and ethical principles, on which based the work of the tax authorities, given the author's idea of the formation of tax culture. We consider the institution of tax advice, its interaction with the tax authorities and its impact on the formation of tax culture.

  13. Diet History Questionnaire II: Size Formats

    Science.gov (United States)

    Two serving size formats are used on the NCI versions of the DHQ as shown below. Format 1 is used for nearly all serving size questions. Format 2 is used only in special cases, where 'never' is allowed as a response.

  14. String Formatting Considered Harmful for Novice Programmers

    Science.gov (United States)

    Hughes, Michael C.; Jadud, Matthew C.; Rodrigo, Ma. Mercedes T.

    2010-01-01

    In Java, "System.out.printf" and "String.format" consume a specialised kind of string commonly known as a format string. In our study of first-year students at the Ateneo de Manila University, we discovered that format strings present a substantial challenge for novice programmers. Focusing on their first laboratory we found that 8% of all the…

  15. Formation of tax culture in Russia

    OpenAIRE

    Halikova Je.A.; Ginijatullina D.R.

    2014-01-01

    This article deals with the mechanism of the formation of tax culture in Russia, moral and ethical principles, on which based the work of the tax authorities, given the author's idea of the formation of tax culture. We consider the institution of tax advice, its interaction with the tax authorities and its impact on the formation of tax culture.

  16. ENDF/B-5 formats manual 1984

    International Nuclear Information System (INIS)

    The ENDF-5 Format, originally the format of the US Evaluated Nuclear Data File ENDF/B-5, was internationally recommended for the computer storage, processing and exchange of evaluated neutron nuclear data. The present document contains the original Formats Manual of 1979, updated with revisions of Nov. 1983. (author)

  17. A new PICL trace file format

    Energy Technology Data Exchange (ETDEWEB)

    Worley, P.H.

    1992-10-01

    A trace file format is described that will be used in future releases of the Portable Instrumented Communication Library (PICL) and ParaGraph. The new format provides improved support for tracing and profiling PICL communication primitives and user-defined events. The new format is also easily extended and may be useful in other instrumentation packages and performance visualization tools.

  18. Tree Formation Using Coordinate Method

    Directory of Open Access Journals (Sweden)

    Monika Choudhary

    2015-06-01

    Full Text Available In this paper we are introducing a new method of tree formation, we propose a coordinate based method by which we can store and access tree structures. As we know in NLP, parsing is the most important module. The output of this module is generally parsed trees. Currently, TAG (Tree Adjoining Grammar is widely used grammar due to its linguistic and formal nature. It is simply tree generating system. The unit structure used in TAG is structured trees. So we used our new method to store trees where we worked on English to Hindi language. We worked on different sentences from English to Hindi, our method is the easiest way to manipulate tree. We have implemented within small corpus and for finite number of structures and further can be extended in future.

  19. Mud Volcanoes Formation And Occurrence

    Science.gov (United States)

    Guliyev, I. S.

    2007-12-01

    Mud volcanoes are natural phenomena, which occur throughout the globe. They are found at a greater or lesser scale in Azerbaijan, Turkmenistan, Georgia, on the Kerch and Taman peninsulas, on Sakhalin Island, in West Kuban, Italy, Romania, Iran, Pakistan, India, Burma, China, Japan, Indonesia, Malaysia, New Zealand, Mexico, Colombia, Trinidad and Tobago, Venezuela and Ecuador. Mud volcanoes are most well-developed in Eastern Azerbaijan, where more than 30% of all the volcanoes in the world are concentrated. More than 300 mud volcanoes have already been recognized here onshore or offshore, 220 of which lie within an area of 16,000 km2. Many of these mud volcanoes are particularly large (up to 400 m high). The volcanoes of the South Caspian form permanent or temporary islands, and numerous submarine banks. Many hypotheses have been developed regarding the origin of mud volcanoes. Some of those hypotheses will be examined in the present paper. Model of spontaneous excitation-decompaction (proposed by Ivanov and Guliev, 1988, 2002). It is supposed that one of major factors of the movement of sedimentary masses and formation of hydrocarbon deposits are phase transitions in sedimentary basin. At phase transitions there are abnormal changes of physical and chemical parameters of rocks. Abnormal (high and negative) pressure takes place. This process is called as excitation of the underground environment with periodicity from several tens to several hundreds, or thousand years. The relationship between mud volcanism and the generation of hydrocarbons, particularly methane, is considered to be a critical factor in mud volcano formation. At high flow rates the gas and sediment develops into a pseudo-liquid state and as flow increases the mass reaches the "so-called hover velocity" where mass transport begins. The mass of fluid moves as a quasi-uniform viscous mass through the sediment pile in a piston like manner until expelled from the surface as a "catastrophic eruption

  20. The formation of postcolonial theory

    Directory of Open Access Journals (Sweden)

    Lazare S. Rukundwa

    2007-05-01

    Full Text Available The purpose of this article is to outline certain options and struggles, which gave rise to postcolonial theory. The author deals with various experiences of anti-slavery and anti-colonial movements in Western and tricontinental countries, comprising the development of postcolonial theory. It is argued that postcolonial theory provides a means of defiance by which any exploitative and discriminative practices, regardless of time and space, can be challenged. The article consists of a section in which terminology is clarified, secondly a discussion of the elements that functioned as justification of the formation of postcolonial theory, namely a humanitarian, economic, political, and religious justification. The role of feminism and anti-colonialism is discussed in the third instance, followed by a reflection on the concept “hybrid identities”.

  1. Positronium formation in condensed matter

    International Nuclear Information System (INIS)

    AMOC (age-momentum correlation) studies of the slowing-down of positronium in condensed matter have demonstrated that positronium formation does not require special sites (e.g., 'free volumes') and diffusion of thermalized e+ to these sites. The differences in the energies E0 at which ps becomes 'permanent' (i.e., does no longer break up into its constituents) between disordered (e.g., organic liquids) and highly ordered (e.g., rare-gas crystals) Ps-formers are explained by the different character of the forces acting on the constituents. It is proposed that information on the break-up may be obtained from the relaxation of the positron spin polarization and that very long slowing-down times may be investigated by ACAR-based AMOC measurements. (orig.)

  2. New Office Software course format

    CERN Multimedia

    HR Department

    2010-01-01

    Always interested to anticipate your training needs, the Technical Training service is pleased to propose two new Office Software course formats : “Focus on... ” : On a monthly basis we will propose a theme such as “Sharepoint Collaboration Workspace” or “Word 2007” or “charts” etc. You will have to send us in advance your questions regarding the proposed topic and register for the course through our Training Catalogue. During the session, our trainer will answer all the questions received and participants will increase their knowledge thanks to the solutions discussed for everyone. The course will last two hours, from 09h00 to 11h00 - with open questions on the proposed topic at the end. “Office software Individual coaching”: If one or several particular topics cause you sleepless nights, you can get the help of our trainer who will come to your workplace for a multiple of 1-hour slots . All fields ...

  3. Formation of $\\phi$ mesic nuclei

    CERN Document Server

    Yamagata-Sekihara, J; Vacas, M J Vicente; Hirenzaki, S

    2010-01-01

    We study the structure and formation of the $\\phi$ mesic nuclei to investigate the in-medium modification of the $\\phi$-meson spectral function at finite density. We consider (${\\bar p},\\phi$), ($\\gamma,p$) and ($\\pi^-,n$) reactions to produce a $\\phi$-meson inside the nucleus and evaluate the effects of its medium modifications to the reaction cross sections. We also estimate the consequences of the uncertainties of the ${\\bar K}$ selfenergy in medium to the $\\phi$-nucleus interaction. We find that it may be possible to see a peak structure in the reaction spectra for the strong attractive potential cases. On the other hand, for strong absorptive interaction cases with relatively weak attractions, it is very difficult to observe clear peaks and we may need to know the spectrum shape in a wide energy region to deduce the properties of $\\phi$.

  4. Foam formation in low gravity

    Science.gov (United States)

    Wessling, Francis C.; Mcmanus, Samuel P.; Matthews, John; Patel, Darayas

    1990-01-01

    An apparatus that produced the first polyurethane foam in low gravity has been described. The chemicals were mixed together in an apparatus designed for operation in low gravity. Mixing was by means of stirring the chemicals with an electric motor and propeller in a mixing chamber. The apparatus was flown on Consort 1, the first low-gravity materials payload launched by a commercial rocket launch team. The sounding rocket flight produced over 7 min of low gravity during which a polyurethane spheroidal foam of approximately 2300 cu cm was formed. Photographs of the formation of the foam during the flight show the development of the spheroidal form. This begins as a small sphere and grows to approximately a 17-cm-diam spheroid. The apparatus will be flown again on subsequent low-gravity flights.

  5. The Formation of Lake Stars

    CERN Document Server

    Tsai, Victor C

    2007-01-01

    Star patterns, reminiscent of a wide range of diffusively controlled growth forms from snowflakes to Saffman-Taylor fingers, are ubiquitous features of ice covered lakes. Despite the commonality and beauty of these ``lake stars'' the underlying physical processes that produce them have not been explained in a coherent theoretical framework. Here we describe a simple mathematical model that captures the principal features of lake-star formation; radial fingers of (relatively warm) water-rich regions grow from a central source and evolve through a competition between thermal and porous media flow effects in a saturated snow layer covering the lake. The number of star arms emerges from a stability analysis of this competition and the qualitative features of this meter-scale natural phenomena are captured in laboratory experiments.

  6. Glass formation in eutectic alloys

    International Nuclear Information System (INIS)

    We have analyzed the glass forming ability around eutectic composition in terms of the competitive growth/formation of primary dendrites, eutectic and glass. It is concluded that the glass forming ability of a eutectic alloy system depends on the type of the eutectics, i.e. symmetric or asymmetric eutectic coupled zone. For the alloy systems with symmetric eutectic coupled zone, the best glass forming alloys should be at or very close to the eutectic composition. For the alloys with asymmetric eutectic coupled zone, which is associated with the irregular eutectic, the best glass forming alloys should be at off-eutectic compositions, probably towards the side of the faceted phase with a high entropy in the phase diagram. (orig.)

  7. MDF: Magnetic Particle Imaging Data Format

    CERN Document Server

    Knopp, Tobias; Bringout, Gael; Ahlborg, Mandy; Rahmer, Jürgen; Hofmann, Martin

    2016-01-01

    Magnetic particle imaging (MPI) is a tomographic method to determine the spatial distribution of magnetic nanoparticles. In this document a file format for the standardized storage of MPI data is introduced. The aim of the Magnetic Particle Imaging Data Format (MDF) is to provide a coherent way of exchanging MPI data acquired with different MPI scanners worldwide. The focus of the file format is on sequence parameters, raw measurement data, calibration data, and reconstruction data. The format is based on the hierarchical document format (HDF) in version 5 (HDF5).

  8. Uranium price formation. Final report

    International Nuclear Information System (INIS)

    The modern uranium industry came into existence in 1946. Until 1966, its sole customer was the Atomic Energy Commission, whose needs for U3O8 relative to industry capacity declined over the years. The development of the commercial market after 1965 coincided with a period of excess capacity and falling nominal and real prices. Gradually in 1973 and dramatically thereafter, market conditions changed and prices rose as utilities sought larger quantities of U3O8 and longer term contracts. Questions about availability of long-run supplies were raised, given the known reserve base. The response of the supply of U3O8 to incentives offered first by the AEC and later by the utilities in the context of new and developing market conventions is examined. The methodology used is microeconomic analysis, qualitatively applied to the history of price formation in the market. Because the study emphasizes the implications of the history of uranium price formation for forecasting supply response, the study presents many different kinds of data and evaluates their quality and appropriateness for forecasting. A simple, very-useful framework for analyzing the history of the market for U3O8 was developed and used to describe supply responses in selected important periods of the industry's development. It is concluded that the response of supply of U3O8 to rising prices or to expectations of demand growth has been impressively strong. The potential reserve inventory is large enough to meet the needs for nuclear power generation through the end of this century. The price necessary to induce producers to find and produce these reserves is uncertain, partly because of problems inherent in estimating long-run supply curves and partly because recent inflation has created major uncertainties about the cost of future supplies

  9. Drill cuttings mount formation study

    Science.gov (United States)

    Teh, Su Yean; Koh, Hock Lye

    2014-07-01

    Oil, Gas and Energy sector has been identified as an essential driving force in the Malaysian Economic Transformation Programs (ETP). Recently confirmed discovery of many offshore oil and gas deposits in Malaysian waters has ignited new confidence in this sector. However, this has also spurred intense interest on safeguarding the health and environment of coastal waters in Malaysia from adverse impact resulting from offshore oil and gas production operation. Offshore discharge of spent drilling mud and rock cuttings is the least expensive and simplest option to dispose of large volumes of drilling wastes. But this onsite offshore disposal may have adverse environmental impacts on the water column and the seabed. It may also pose occupational health hazards to the workers living in the offshore platforms. It is therefore important to model the transport and deposition of drilling mud and rock cuttings in the sea to enable proper assessment of their adverse impacts on the environment and the workers. Further, accumulation of drill particles on the seabed may impede proper operation of pipelines on the seabed. In this paper, we present an in-house application model TUNA-PT developed to cater to local oil and gas industry needs to simulate the dispersion and mount formation of drill cuttings by offshore oil and gas exploration and production platforms. Using available data on Malaysian coastal waters, simulation analyses project a pile formation on the seabed with a maximum height of about 1 m and pile radius of around 30 to 50 m. Simulated pile heights are not sensitive to the heights of release of the cuttings as the sensitivity has been mitigated by the depth of water.

  10. Engram Formation in Psychiatric Disorders

    Directory of Open Access Journals (Sweden)

    Peter J. Gebicke-Haerter

    2014-05-01

    Full Text Available Environmental factors substantially influence beginning and progression of mental illness, reinforcing or reducing the consequences of genetic vulnerability. Often initiated by early traumatic events, engrams or memories are formed that may give rise to a slow and subtle progression of psychiatric disorders. The large delay between beginning and time of onset (diagnosis may be explained by efficient compensatory mechanisms observed in brain metabolism that use optional pathways in highly redundant molecular interactions.To this end, research has to deal with mechanisms of learning and long-term memory formation, which involves a epigenetic changes, b altered neuronal activities and c changes in neuron-glia communication. On the epigenetic level, apparently DNA-methylations are more stable than histone modifications, although both closely interact. Neuronal activities basically deliver digital information, which clearly can serve as basis for memory formation (LTP. However, research in this respect has long time neglected the importance of glia. They are more actively involved in the control of neuronal activities than thought before. They can both reinforce and inhibit neuronal activities by transducing neuronal information from frequency-encoded to amplitude and frequency-modulated calcium wave patterns spreading in the glial syncytium by use of gap junctions. In this way, they serve integrative functions. In conclusion, we are dealing with two concepts of encoding information that mutually control each other and synergize: a digital (neuronal and a wave-like (glial computing, forming neuron-glia functional units with inbuilt feedback loops to maintain balance of excitation and inhibition. To better understand mental illness, we have to gain more insight into the dynamics of adverse environmental impact on those cellular and molecular systems. This report summarizes existing knowledge and draws some outline about further research in molecular

  11. Biomineralization: mineral formation by organisms

    Science.gov (United States)

    Addadi, Lia; Weiner, Steve

    2014-09-01

    Organisms form many different types of minerals, with diverse shapes and sizes. These minerals fulfill a variety of functions. Inspired by the late H A Lowenstam, Steve Weiner and Lia Addadi have addressed many questions that relate to the mechanisms by which biological organisms produce these mineral phases and how their structures relate to their functions. Addadi and Weiner have explored the manner in which macromolecules extracted from mineralized tissues can interact with some crystal planes and not others, how these macromolecules can be occluded inside the forming crystals residing preferentially on specific crystal planes, and how they can induce one polymorph of calcium carbonate and not another to nucleate. Addadi and Weiner have also identified a novel strategy used by the sea urchin to form its smooth and convoluted mineralized skeletal elements. The strategy involves the initial production by cells of a highly disordered mineral precursor phase in vesicles, and then the export of this so-called amorphous phase to the site of skeletal formation, where it crystallizes. This strategy is now known to be used by many different invertebrate phyla, as well as by vertebrates to build bones and teeth. One of the major current research aims of the Weiner--Addadi group is to understand the biomineralization pathways whereby ions are extracted from the environment, are transported and deposited inside cells within vesicles, how these disordered phases are then transferred to the site of skeletal formation, and finally how the so-called amorphous phase crystallizes. Biology has clearly evolved unique strategies for forming crystalline minerals. Despite more than 300 years of research in this field, many challenging questions still remain unanswered.

  12. Formation and Evolution of Protoatmospheres

    Science.gov (United States)

    Massol, H.; Hamano, K.; Tian, F.; Ikoma, M.; Abe, Y.; Chassefière, E.; Davaille, A.; Genda, H.; Güdel, M.; Hori, Y.; Leblanc, F.; Marcq, E.; Sarda, P.; Shematovich, V. I.; Stökl, A.; Lammer, H.

    2016-09-01

    The origin and evolution of planetary protoatmospheres in relation to the protoplanetary disk is discussed. The initial atmospheres of planets can mainly be related via two formation scenarios. If a protoplanetary core accretes mass and grows inside the gas disk, it can capture H2, He and other gases from the disk. When the gas of the disk evaporates, the core that is surrounded by the H2/He gas envelope is exposed to the high X-ray and extreme ultraviolet flux and stellar wind of the young host star. This period can be considered as the onset of atmospheric escape. It is shown that lower mass bodies accrete less gas and depending on the host stars radiation environment can therefore lose the gaseous envelope after tens or hundreds of million years. Massive cores may never get rid of their captured hydrogen envelopes and remain as sub-Neptunes, Neptunes or gas giants for their whole life time. Terrestrial planets which may have lost the captured gas envelope by thermal atmospheric escape, or which accreted after the protoplanetary nebula vanished will produce catastrophically outgassed steam atmospheres during the magma ocean solidification process. These steam atmospheres consist mainly of water and CO2 that was incorporated into the protoplanet during its accretion. Planets, which are formed in the habitable zone, solidify within several million years. In such cases the outgassed steam atmospheres cool fast, which leads to the condensation of water and the formation of liquid oceans. On the other hand, magma oceans are sustained for longer if planets form inside a critical distance, even if they outgassed a larger initial amount of water. In such cases the steam atmosphere could remain 100 million years or for even longer. Hydrodynamic atmospheric escape will then desiccate these planets during the slow solidification process.

  13. Format SPARQL Query Results into HTML Report

    Directory of Open Access Journals (Sweden)

    Dr Sunitha Abburu

    2013-07-01

    Full Text Available SPARQL is one of the powerful query language for querying semantic data. It is recognized by the W3C as a query language for RDF. As an efficient query language for RDF, it has defined several query result formats such as CSV, TSV and XML etc. These formats are not attractive, understandable and readable. The results need to be converted in an appropriate format so that user can easily understand. The above formats require additional transformations or tool support to represent the query result in user readable format. The main aim of this paper is to propose a method to build HTML report dynamically for SPARQL query results. This enables SPARQL query result display, in HTML report format easily, in an attractive understandable format without the support of any additional or external tools or transformation.

  14. Improving the Formatting Tools of CDS Invenio

    CERN Document Server

    Caffaro, J; Pu Faltings, Pearl

    2006-01-01

    CDS Invenio is the web-based integrated digital library system developed at CERN. It is a strategical tool that supports the archival and open dissemination of documents produced by CERN researchers. This paper reports on my Master’s thesis work done on BibFormat, a module in CDS Invenio, which formats documents metadata. The goal of this project was to implement a completely new formatting module for CDS Invenio. In this report a strong emphasis is put on the user-centered design of the new BibFormat. The bibliographic formatting process and its requirements are discussed. The task analysis and its resulting interaction model are detailed. The document also shows the implemented user interface of BibFormat and gives the results of the user evaluation of this interface. Finally the results of a small usability study of the formats included in CDS Invenio are discussed.

  15. Formation Flying for Distributed InSAR

    Science.gov (United States)

    Scharf, Daniel P.; Murray, Emmanuell A.; Ploen, Scott R.; Gromov, Konstantin G.; Chen, Curtis W.

    2006-01-01

    We consider two spacecraft flying in formation to create interferometric synthetic aperture radar (InSAR). Several candidate orbits for such in InSar formation have been previously determined based on radar performance and Keplerian orbital dynamics. However, with out active control, disturbance-induced drift can degrade radar performance and (in the worst case) cause a collision. This study evaluates the feasibility of operating the InSAR spacecraft as a formation, that is, with inner-spacecraft sensing and control. We describe the candidate InSAR orbits, design formation guidance and control architectures and algorithms, and report the (Delta)(nu) and control acceleration requirements for the candidate orbits for several tracking performance levels. As part of determining formation requirements, a formation guidance algorithm called Command Virtual Structure is introduced that can reduce the (Delta)(nu) requirements compared to standard Leader/Follower formation approaches.

  16. Fibril formation from pea protein and subsequent gel formation.

    Science.gov (United States)

    Munialo, Claire Darizu; Martin, Anneke H; van der Linden, Erik; de Jongh, Harmen H J

    2014-03-19

    The objective of this study was to characterize fibrillar aggregates made using pea proteins, to assemble formed fibrils into protein-based gels, and to study the rheological behavior of these gels. Micrometer-long fibrillar aggregates were observed after pea protein solutions had been heated for 20 h at pH 2.0. Following heating of pea proteins, it was observed that all of the proteins were hydrolyzed into peptides and that 50% of these peptides were assembled into fibrils. Changes on a structural level in pea proteins were studied using circular dichroism, transmission electron microscopy, and particle size analysis. During the fibril assembly process, an increase in aggregate size was observed, which coincided with an increase in thioflavin T binding, indicating the presence of β-sheet aggregates. Fibrils made using pea proteins were more branched and curly. Gel formation of preformed fibrils was induced by slow acidification from pH 7.0 to a final pH of around pH 5.0. The ability of pea protein-based fibrillar gels to fracture during an amplitude sweep was comparable to those of soy protein and whey protein-based fibrillar gels, although gels prepared from fibrils made using pea protein and soy protein were weaker than those of whey protein. The findings show that fibrils can be prepared from pea protein, which can be incorporated into protein-based fibrillar gels.

  17. Magnetic Assisted Colloidal Pattern Formation

    Science.gov (United States)

    Yang, Ye

    Pattern formation is a mysterious phenomenon occurring at all scales in nature. The beauty of the resulting structures and myriad of resulting properties occurring in naturally forming patterns have attracted great interest from scientists and engineers. One of the most convenient experimental models for studying pattern formation are colloidal particle suspensions, which can be used both to explore condensed matter phenomena and as a powerful fabrication technique for forming advanced materials. In my thesis, I have focused on the study of colloidal patterns, which can be conveniently tracked in an optical microscope yet can also be thermally equilibrated on experimentally relevant time scales, allowing for ground states and transitions between them to be studied with optical tracking algorithms. In particular, I have focused on systems that spontaneously organize due to particle-surface and particle-particle interactions, paying close attention to systems that can be dynamically adjusted with an externally applied magnetic or acoustic field. In the early stages of my doctoral studies, I developed a magnetic field manipulation technique to quantify the adhesion force between particles and surfaces. This manipulation technique is based on the magnetic dipolar interactions between colloidal particles and their "image dipoles" that appear within planar substrate. Since the particles interact with their own images, this system enables massively parallel surface force measurements (>100 measurements) in a single experiment, and allows statistical properties of particle-surface adhesion energies to be extracted as a function of loading rate. With this approach, I was able to probe sub-picoNewton surface interactions between colloidal particles and several substrates at the lowest force loading rates ever achieved. In the later stages of my doctoral studies, I focused on studying patterns formed from particle-particle interaction, which serve as an experimental model of

  18. Cataract formation following vitreoretinal procedures

    Directory of Open Access Journals (Sweden)

    Feng H

    2014-09-01

    Full Text Available Hao Feng, Ron A Adelman Department of Ophthalmology and Visual Science, Yale University School of Medicine, New Haven, CT, USA Purpose: To evaluate the incidence and prevalence of cataract formation, progression, and extraction in patients that underwent vitreoretinal procedures and to evaluate factors that can potentially predispose patients to postoperative cataracts.Materials and methods: The medical records of consecutive patients who underwent vitreoretinal surgery at the Yale Eye Center with at least 6 months of follow-up and no prior intraocular surgery were obtained. Preoperative, intraoperative, and postoperative data were recorded and analyzed in this retrospective observational study. The main outcome measures were defined as cataract extraction, formation, and progression after vitreoretinal procedures. The lens status of the surgical eye was recorded preoperatively and at 1 month, 3 months, 6 months, 12 months, 24 months, and 36 months postoperatively.Results: A total of 193 eyes of 180 patients fulfilled the inclusion criteria. The percentages of eyes with mild lens change were 96% after 20-gauge pars plana vitrectomy (PPV, 72% after small gauge (23- and 25-gauge PPV, 38% after scleral buckle (SB, 38% after pneumatic retinopexy (PR, and 91% after PPV plus SB (PPV+SB. Posterior subcapsular and nuclear sclerotic cataracts were the most common with almost all developing within 24 months. There was no statistically significant difference (P=1.00 between the rate of cataract extraction after 20-gauge (41% and small gauge PPV (42%, but there was a statistically significant difference between PPV and non-PPV (SB, 6%; PR, 7%; P<0.001 and PPV and PPV+SB groups (69%; P=0.0063.Conclusion: Cataracts were common following PPV regardless of the gauge. SB and PR led to the lowest while PPV+SB led to the highest risk of postoperative cataracts. Keywords: cataracts, vitreoretinal surgery, vitrectomy, scleral buckle, pneumatic retinopexy

  19. Pattern Formation and Complexity Emergence

    Science.gov (United States)

    Berezin, Alexander A.

    2001-03-01

    Success of nonlinear modelling of pattern formation and self-organization encourages speculations on informational and number theoretical foundations of complexity emergence. Pythagorean "unreasonable effectiveness of integers" in natural processes is perhaps extrapolatable even to universal emergence "out-of-nothing" (Leibniz, Wheeler). Because rational numbers (R = M/N) are everywhere dense on real axis, any digital string (hence any "book" from "Library of Babel" of J.L.Borges) is "recorded" infinitely many times in arbitrary many rationals. Furthermore, within any arbitrary small interval there are infinitely many Rs for which (either or both) integers (Ms and Ns) "carry" any given string of any given length. Because any iterational process (such as generation of fractal features of Mandelbrot Set) is arbitrary closely approximatable with rational numbers, the infinite pattern of integers expresses itself in generation of complexity of the world, as well as in emergence of the world itself. This "tunnelling" from Platonic World ("Platonia" of J.Barbour) to a real (physical) world is modern recast of Leibniz's motto ("for deriving all from nothing there suffices a single principle").

  20. Collagen fibril formation during development

    International Nuclear Information System (INIS)

    Studies with embryonic skin and bone suggested that the aminopropeptide (AP) and carboxylpropeptide (CP) of type I pro-callagen (pro-col) play a role in fibril formation. Chick leg metatarsal tendons were studied by electron microscopy. AP and CP of type I pro-col were purified from chick leg tendons; antibodies developed in rabbits and purity tested by radioimmunoassays. Antibodies were used for immunofluorescence microscopy (IFM) and immunoblotting (IB). The peritendineum, consisting of thin 20-30 nm fibrils, revealed the AP of type I and type III procol. In the tendon area, collagen fibrils were arranged within small compartments and were of uniform diameter at 10d, 14d and 18d. However, beyond 21d, there was confluency of the compartments and a wide range of fibril diameters. IFM revealed fine streaks of collagen, staining with the AP of type I throughout the tendon. The CP was mainly intracellular with only a small amount present in the extracellular space. IB revealed procollagen, pN-collagen (AP+collagen) and pC-collagen, (CP+collagen) at all stages of development. Ratios of pN/pC collagen, determined by spectrophotometric scanning of autoradiographs, correlated well with the distribution of fibril diameter. This study suggests the hypothesis that AP initiates fibrillogenesis while CP may regulate additional fibril growth

  1. Fertilization and early seed formation.

    Science.gov (United States)

    Dumas, Christian; Rogowsky, Peter

    2008-10-01

    The double fertilization of flowering plants is a complex process, encompassing multiple steps. From its discovery more than a century ago, many useful descriptive approaches have been employed to better unveil specific steps/mechanisms. More recently, the development of an in vitro assay developed in our laboratory, has allowed a better understanding of this phenomenon. However, in vitro methods may show some limitations. The search for complementary strategies, especially with the search of mutants affected in the fertilization step allowed one to elucidate this critical and unique phenomenon in living organisms. Genes involved in pollen tube guidance or pollen discharge in synergids have been identified, as well as genes exhibiting differential expression in sperm, egg and central cells before and after fertilization. A calcium wave proved to correspond to the first cellular event seen after cytoplasmic fusion in the fertilized egg cell or zygote, which develops into a multi-cellular organism with an elaborate body plan. The development of the fertilized central cell into a nourishing tissue (endosperm) starts with the formation of the coenocyte, a multinuclear single cell unique in the plant kingdom, cellularization occurring later on. The balance of the paternal and maternal genomes, which is under the control of the FIS polycomb group complex, was found to be of the utmost importance for the successful development of the seed.

  2. New Office Software course format!

    CERN Multimedia

    HR Department

    Always keen to anticipate your  training needs, the Technical Training service is pleased to propose two new Office Software course formats: “Focus on... ”:  On a monthly basis we will propose a theme such as “Sharepoint Collaboration Workspace” or “Word 2007” or “charts”, etc.  You will be invited to send us in advance your questions regarding the proposed topic and register  for the course through our Training Catalogue. During the session, our trainer will answer all the questions received and participants will increase their knowledge thanks to the solutions discussed for everyone. The course will last two hours, from 9-00 to 11-00 a.m. - with open questions on the proposed topic at the end.   “Office software Individual coaching”: If one or more specific topics are causing you sleepless nights, you can get the help of our trainer who will ...

  3. New Office Software course format!

    CERN Multimedia

    HR Department

    2009-01-01

    Always keen to anticipate your  training needs, the Technical Training service is pleased to propose two new Office Software course formats: “Focus on... ”:  On a monthly basis we will propose a theme such as “Sharepoint Collaboration Workspace” or “Word 2007” or “charts”, etc.  You will be invited to send us in advance your questions regarding the proposed topic and register  for the course through our Training Catalogue. During the session, our trainer will answer all the questions received and participants will increase their knowledge thanks to the solutions discussed for everyone. The course will last two hours, from 9-00 to 11-00 a.m. - with open questions on the proposed topic at the end.   “Office software Individual coaching”: If one or more specific topics are causing you sleepless nights, you can get the help of our trainer who will ...

  4. STAR FORMATION IN DENSE CLUSTERS

    International Nuclear Information System (INIS)

    A model of core-clump accretion with equally likely stopping describes star formation in the dense parts of clusters, where models of isolated collapsing cores may not apply. Each core accretes at a constant rate onto its protostar, while the surrounding clump gas accretes as a power of protostar mass. Short accretion flows resemble Shu accretion and make low-mass stars. Long flows resemble reduced Bondi accretion and make massive stars. Accretion stops due to environmental processes of dynamical ejection, gravitational competition, and gas dispersal by stellar feedback, independent of initial core structure. The model matches the field star initial mass function (IMF) from 0.01 to more than 10 solar masses. The core accretion rate and the mean accretion duration set the peak of the IMF, independent of the local Jeans mass. Massive protostars require the longest accretion durations, up to 0.5 Myr. The maximum protostar luminosity in a cluster indicates the mass and age of its oldest protostar. The distribution of protostar luminosities matches those in active star-forming regions if protostars have a constant birthrate but not if their births are coeval. For constant birthrate, the ratio of young stellar objects to protostars indicates the star-forming age of a cluster, typically ∼1 Myr. The protostar accretion luminosity is typically less than its steady spherical value by a factor of ∼2, consistent with models of episodic disk accretion.

  5. Dark Energy and Structure Formation

    International Nuclear Information System (INIS)

    We study the gravitational dynamics of dark energy configurations. We report on the time evolution of the dark energy field configurations as well as the time evolution of the energy density to demonstrate the gravitational collapse of dark energy field configurations. We live in a Universe which is dominated by Dark Energy. According to current estimates about 75% of the Energy Density is in the form of Dark Energy. Thus when we consider gravitational dynamics and Structure Formation we expect Dark Energy to play an important role. The most promising candidate for dark energy is the energy density of fields in curved space-time. It therefore become a pressing need to understand the gravitational dynamics of dark energy field configurations. We develop and describe the formalism to study the gravitational collapse of fields given any general potential for the fields. We apply this formalism to models of dark energy motivated by particle physics considerations. We solve the resulting evolution equations which determine the time evolution of field configurations as well as the dynamics of space-time. Our results show that gravitational collapse of dark energy field configurations occurs and must be considered in any complete picture of our universe.

  6. Dark Energy and Structure Formation

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Anupam, E-mail: morisi@ific.uv.es [Physics Department, L.N. Mittal I.I.T, Jaipur, Rajasthan (India)

    2010-11-01

    We study the gravitational dynamics of dark energy configurations. We report on the time evolution of the dark energy field configurations as well as the time evolution of the energy density to demonstrate the gravitational collapse of dark energy field configurations. We live in a Universe which is dominated by Dark Energy. According to current estimates about 75% of the Energy Density is in the form of Dark Energy. Thus when we consider gravitational dynamics and Structure Formation we expect Dark Energy to play an important role. The most promising candidate for dark energy is the energy density of fields in curved space-time. It therefore become a pressing need to understand the gravitational dynamics of dark energy field configurations. We develop and describe the formalism to study the gravitational collapse of fields given any general potential for the fields. We apply this formalism to models of dark energy motivated by particle physics considerations. We solve the resulting evolution equations which determine the time evolution of field configurations as well as the dynamics of space-time. Our results show that gravitational collapse of dark energy field configurations occurs and must be considered in any complete picture of our universe.

  7. Pattern formation in centrosome assembly.

    Science.gov (United States)

    Mahen, Robert; Venkitaraman, Ashok R

    2012-02-01

    A striking but poorly explained feature of cell division is the ability to assemble and maintain organelles not bounded by membranes, from freely diffusing components in the cytosol. This process is driven by information transfer across biological scales such that interactions at the molecular scale allow pattern formation at the scale of the organelle. One important example of such an organelle is the centrosome, which is the main microtubule organising centre in the cell. Centrosomes consist of two centrioles surrounded by a cloud of proteins termed the pericentriolar material (PCM). Profound structural and proteomic transitions occur in the centrosome during specific cell cycle stages, underlying events such as centrosome maturation during mitosis, in which the PCM increases in size and microtubule nucleating capacity. Here we use recent insights into the spatio-temporal behaviour of key regulators of centrosomal maturation, including Polo-like kinase 1, CDK5RAP2 and Aurora-A, to propose a model for the assembly and maintenance of the PCM through the mobility and local interactions of its constituent proteins. We argue that PCM structure emerges as a pattern from decentralised self-organisation through a reaction-diffusion mechanism, with or without an underlying template, rather than being assembled from a central structural template alone. Self-organisation of this kind may have broad implications for the maintenance of mitotic structures, which, like the centrosome, exist stably as supramolecular assemblies on the micron scale, based on molecular interactions at the nanometer scale. PMID:22245706

  8. Clumpy Disc and Bulge Formation

    CERN Document Server

    Perez, J; Tissera, P; Michel-Dansac, L

    2013-01-01

    We present a set of hydrodynamical/Nbody controlled simulations of isolated gas rich galaxies that self-consistently include SN feedback and a detailed chemical evolution model, both tested in cosmological simulations. The initial conditions are motivated by the observed star forming galaxies at z ~ 2-3. We find that the presence of a multiphase interstellar media in our models promotes the growth of disc instability favouring the formation of clumps which in general, are not easily disrupted on timescales compared to the migration time. We show that stellar clumps migrate towards the central region and contribute to form a classical-like bulge with a Sersic index, n > 2. Our physically-motivated Supernova feedback has a mild influence on clump survival and evolution, partially limiting the mass growth of clumps as the energy released per Supernova event is increased, with the consequent flattening of the bulge profile. This regulation does not prevent the building of a classical-like bulge even for the most ...

  9. Rowing sportswomen motor actions formation

    Directory of Open Access Journals (Sweden)

    Volodymyr Bogush

    2015-08-01

    Full Text Available Purpose: to study the formation of motor action sportswomen different ages depending on the level of sportsmanship. Material and Methods: girls which are specialized in a boat-racing in age groups 13–14 years inspected, 15–16 years, 17–18 years, in every group was for 20–25 persons, in all 72 sportswomen. Motive actions were probed on the method of measuring of training effect developed by us an action, and also the functional state was determined by methods: measuring of sensorimotor reaction is on sound and light irritants, speed of current of air, exactness of implementation of the set muscular effort. Results: testing showed the dynamics of forming motive, namely technique of mastering of receptions and actions, reliability, presence of errors, efficiency of active voice of consciousness in correct implementation of motion in a biomechanics relation. Conclusions: application of this method in the process of sporting preparation will allow to define quality of mastering of technique of the proper motive actions, forming of abilities, subsequent learning and becoming of more difficult motive skills

  10. Testing Models for Structure Formation

    CERN Document Server

    Kaiser, N

    1993-01-01

    I review a number of tests of theories for structure formation. Large-scale flows and IRAS galaxies indicate a high density parameter $\\Omega \\simeq 1$, in accord with inflationary predictions, but it is not clear how this meshes with the uniformly low values obtained from virial analysis on scales $\\sim$ 1Mpc. Gravitational distortion of faint galaxies behind clusters allows one to construct maps of the mass surface density, and this should shed some light on the large vs small-scale $\\Omega$ discrepancy. Power spectrum analysis reveals too red a spectrum (compared to standard CDM) on scales $\\lambda \\sim 10-100$ $h^{-1}$Mpc, but the gaussian fluctuation hypothesis appears to be in good shape. These results suggest that the problem for CDM lies not in the very early universe --- the inflationary predictions of $\\Omega = 1$ and gaussianity both seem to be OK; furthermore, the COBE result severely restricts modifications such as tilting the primordial spectrum --- but in the assumed matter content. The power s...

  11. Autonomous Formations of Multi-Agent Systems

    Science.gov (United States)

    Dhali, Sanjana; Joshi, Suresh M.

    2013-01-01

    Autonomous formation control of multi-agent dynamic systems has a number of applications that include ground-based and aerial robots and satellite formations. For air vehicles, formation flight ("flocking") has the potential to significantly increase airspace utilization as well as fuel efficiency. This presentation addresses two main problems in multi-agent formations: optimal role assignment to minimize the total cost (e.g., combined distance traveled by all agents); and maintaining formation geometry during flock motion. The Kuhn-Munkres ("Hungarian") algorithm is used for optimal assignment, and consensus-based leader-follower type control architecture is used to maintain formation shape despite the leader s independent movements. The methods are demonstrated by animated simulations.

  12. Giant Planet Formation, Evolution, and Internal Structure

    CERN Document Server

    Helled, Ravit; Podolak, Morris; Boley, Aaron; Meru, Farzana; Nayakshin, Sergei; Fortney, Jonathan J; Mayer, Lucio; Alibert, Yann; Boss, Alan P

    2013-01-01

    The large number of detected giant exoplanets offers the opportunity to improve our understanding of the formation mechanism, evolution, and interior structure of gas giant planets. The two main models for giant planet formation are core accretion and disk instability. There are substantial differences between these formation models, including formation timescale, favorable formation location, ideal disk properties for planetary formation, early evolution, planetary composition, etc. First, we summarize the two models including their substantial differences, advantages, and disadvantages, and suggest how theoretical models should be connected to available (and future) data. We next summarize current knowledge of the internal structures of solar- and extrasolar- giant planets. Finally, we suggest the next steps to be taken in giant planet exploration.

  13. Stereoregularity Drives Precipitation in Polyelectrolyte Complex Formation

    Science.gov (United States)

    Tirrell, Matthew; Perry, Sarah; Leon, Lorraine; Kade, Matthew; Priftis, Dimitris; Black, Katie; Hoffman, Kyle; Whitmer, Jonathan; Qin, Jian; de Pablo, Juan

    2014-03-01

    This study investigates the effect of stereoregularity on the formation of polypeptide-based complex formation and assembly into micelles, hydrogels and ordered phases. We demonstrate that fluid complex coacervate formation (rather than solid complex precipitation) between oppositely charged polypeptides requires at least one racemic partner in order to disrupt backbone hydrogen bonding networks and prevent the hydrophobic collapse of the polymers into compact, fibrillar secondary structures. Computer simulations bear this out and enable visualization of the molecular structure of the complexes. The ability to choose between conditions of fluid phase formation and solid phase formation is a useful tool in developing new self-assembled materials based on polyelectrolyte complex formation. Support from the Argonne National Laboratory Laboratory Research and Development Program (2011-217) is gratefully acknowledged.

  14. Formation temperatures of thermogenic and biogenic methane

    Science.gov (United States)

    Stolper, D.A.; Lawson, M.; Davis, C.L.; Ferreira, A.A.; Santos Neto, E. V.; Ellis, G.S.; Lewan, M.D.; Martini, A.M.; Tang, Y.; Schoell, M.; Sessions, A.L.; Eiler, J.M.

    2014-01-01

    Methane is an important greenhouse gas and energy resource generated dominantly by methanogens at low temperatures and through the breakdown of organic molecules at high temperatures. However, methane-formation temperatures in nature are often poorly constrained. We measured formation temperatures of thermogenic and biogenic methane using a “clumped isotope” technique. Thermogenic gases yield formation temperatures between 157° and 221°C, within the nominal gas window, and biogenic gases yield formation temperatures consistent with their comparatively lower-temperature formational environments (<50°C). In systems where gases have migrated and other proxies for gas-generation temperature yield ambiguous results, methane clumped-isotope temperatures distinguish among and allow for independent tests of possible gas-formation models.

  15. Molecular hydrogen formation in the interstellar medium

    CERN Document Server

    Cazaux, S

    2002-01-01

    We have developed a model for molecular hydrogen formation under astrophysically relevant conditions. This model takes fully into account the presence of both physisorbed and chemisorbed sites on the surface, allows quantum mechanical diffusion as well as thermal hopping for absorbed H-atoms, and has been benchmarked versus recent laboratory experiments on H2 formation on silicate surfaces. The results show that H2 formation on grain surface is efficient in the interstellar medium up to some 300K. At low temperatures (<100K), H2 formation is governed by the reaction of a physisorbed H with a chemisorbed H. At higher temperatures, H2 formation proceeds through reaction between two chemisorbed H atoms. We present simple analytical expressions for H2 formation which can be adopted to a wide variety of surfaces once their surfaces characteristics have been determined experimentally.

  16. Black-hole formation from stellar collapse

    International Nuclear Information System (INIS)

    I review the end-state of massive stellar evolution, following the evolution of these massive stars from the onset of collapse through the formation of a compact remnant and the possible supernova or hypernova explosion. In particular, I concentrate on the formation of black holes from stellar collapse: the fraction of stars that form black holes, the black-hole mass distribution and the velocities these black-hole remnants may receive during their formation process

  17. Models of formation of lignin polymer

    OpenAIRE

    Gričar, Jožica; Oven, Primož; Čufar, Katarina

    2005-01-01

    In paper, two models of formation of lignin macromolecule are described. Random coupling model suggests lignin formation process through coupling of monomer radicals to growing lignin polymer in a near-random fashion. According to the dirigent protein model, process of lignin polymerization is fully controlled by specific dirigent proteins that direct formation of individual bonds. Critical judgements and scientific opinions of both models are given.

  18. Education, values and union formation in Sweden

    OpenAIRE

    Thomson, Elizabeth; Bernhardt, Eva

    2007-01-01

    Education provides opportunities for as well as barriers and alternatives to the formation of intimate unions. In this study, we consider the several mechanisms through which educational attainment may delay or speed up union formation. As do most other studies, we include both educational enrolment and attainment, the former viewed as a constraint on union formation, the latter facilitating the accumulation of resources that enable young couples to establish their own household. A third comp...

  19. Massive Star Formation : the Role of Disks

    OpenAIRE

    Fallscheer, Cassandra

    2010-01-01

    In this thesis, I study three different evolutionary stages of the massive star formation process looking for supporting evidence for an accretion-based formation scenario of massive stars. The first source studied, the Infrared Dark Cloud IRDC 18223-3, is at one of the earliest observable phases of massive star formation. This source is characterized by a cone-shaped molecular outflow component which is used to establish the outflow orientation. A velocity gradient traced by the molecule ...

  20. Control of star formation by supersonic turbulence

    OpenAIRE

    Mac Low, Mordecai-Mark; Klessen, Ralf S.

    2003-01-01

    Understanding the formation of stars in galaxies is central to much of modern astrophysics. For several decades it has been thought that stellar birth is primarily controlled by the interplay between gravity and magnetostatic support, modulated by ambipolar diffusion. Recently, however, both observational and numerical work has begun to suggest that support by supersonic turbulence rather than magnetic fields controls star formation. In this review we outline a new theory of star formation re...

  1. Formation temperatures of thermogenic and biogenic methane

    OpenAIRE

    Stolper, D. A.; Lawson, M.; Davis, C. L.; Ferreira, A. A.; Santos Neto, E. V.; Ellis, G.S.; Lewan, M.D.; Martini, A. M.; Tang, Y.; Schoell, M.; Sessions, A.L.; Eiler, J. M.

    2014-01-01

    Methane is an important greenhouse gas and energy resource generated dominantly by methanogens at low temperatures and through the breakdown of organic molecules at high temperatures. However, methane-formation temperatures in nature are often poorly constrained. We measured formation temperatures of thermogenic and biogenic methane using a “clumped isotope” technique. Thermogenic gases yield formation temperatures between 157° and 221°C, within the nominal gas window, and biogenic gases yiel...

  2. Entanglement of Formation for Quantum States

    Institute of Scientific and Technical Information of China (English)

    ZHAO Hui; WANG Zhi-Xi

    2007-01-01

    We investigate the entanglement of formation for a class of high-dimensional quantum mixed states. We present a kind of generalized concurrence for a class of high-dimensional quantum pure states such that the entanglement of formation is a monotonically increasing convex function of the generalized concurrence. From the monotonicity and convexity the entanglement of formation for a class of high-dimensional mixed states has been calculated analytically.

  3. COOPERATIVE TEAM FORMATION USING DISTRIBUTED DECOMPOSITION KNOWLEDGE

    OpenAIRE

    Carpenter, Martin Richard John

    2010-01-01

    Cooperative team formation using distributed decomposition knowledgeA thesis submitted in August 2010 by Martin Carpenter to the University ofManchester for the degree of Doctor of Philosophy. In recent years, the problem of automating the formation of Virtual Organisations (VO) has risen to prominence. Work in this area has typically considered the process of VO formation to be a centralised process driven by a company with responsibility for the business opportunity.Such systems use two mai...

  4. Precursors of Young Women's Family Formation Pathways

    OpenAIRE

    Amato, Paul R.; Landale, Nancy S.; Havasevich, Tara C.; Booth, Alan; Eggebeen, David J.; Schoen, Robert; McHale, Susan M.

    2008-01-01

    We used latent class analysis to create family formation pathways for women between the ages of 18 and 23. Input variables included cohabitation, marriage, parenthood, full-time employment, and attending school. Data (n = 2,290) came from Waves I and III of the National Longitudinal Study of Adolescent Health (Add Health). The analysis revealed seven latent pathways: college-no family formation (29%), high school-no family formation (19%), cohabitation without children (15%), married mothers ...

  5. Complications and mortality following stoma formation.

    OpenAIRE

    Harris, D. A.; Egbeare, D.; Jones, S; Benjamin, H; Woodward, A; Foster, M E

    2005-01-01

    INTRODUCTION: As stoma formation is thought to be declining, we performed a study to evaluate the rate of stoma formation and the impact on stoma complication rates, together with risk factors for complications. PATIENTS AND METHODS: Stoma incidence, individual complications and mortality rates were retrieved from a stoma nurse database of 345 stomas created over an 8-year period. RESULTS: Stoma formation increased over the study period, although the incidence of complications declined. Stoma...

  6. New Particle Formation Study Final Campaign Report

    Energy Technology Data Exchange (ETDEWEB)

    Smith, JN; McMurry, PH [University of Minnesota

    2015-01-01

    The scientific foci of the New Particle Formation Study were the formation and evolution of atmospheric aerosols and the impacts of newly formed particles on cloud processes. Specifically, we planned to: (1) to identify the species and mechanisms responsible for the initial steps of new particle formation, i.e., the formation of thermodynamically stable clusters; (2) investigate the role of acid-base chemistry in new particle growth through measurements of ammonia and amines as well as organic and inorganic acids in both atmospheric nanoparticles and the gas phase; (3) investigate the contribution of other surface area or volume-controlled processes to nanoparticle formation and growth; (4) create a comprehensive dataset related to new particle formation and growth that can be used as input for our own thermodynamic models as well as the modeling efforts by our Department of Energy (DOE) Aerosol Life Cycle working group collaborators; (5) characterize the increase of the number and activity of cloud condensation nuclei (CCN) due to particle formation and growth; (6) determine the regional extent of new particle formation to address the role that atmospheric transport plays in determining the impacts, if any, of new particle formation on cloud number and properties.

  7. Cellular chain formation in Escherichia coli biofilms

    DEFF Research Database (Denmark)

    Vejborg, Rebecca Munk; Klemm, Per

    2009-01-01

    In this study we report on a novel structural phenotype in Escherichia coli biofilms: cellular chain formation. Biofilm chaining in E. coli K-12 was found to occur primarily by clonal expansion, but was not due to filamentous growth. Rather, chain formation was the result of intercellular......; type I fimbriae expression significantly reduced cellular chain formation, presumably by steric hindrance. Cellular chain formation did not appear to be specific to E coli K-12. Although many urinary tract infection (UTI) isolates were found to form rather homogeneous, flat biofilms, three isolates...

  8. Antagonistic formation motion of cooperative agents

    Institute of Scientific and Technical Information of China (English)

    卢婉婷; 代明香; 薛方正

    2015-01-01

    This paper investigates a new formation motion problem of a class of first-order multi-agent systems with antagonis-tic interactions. A distributed formation control algorithm is proposed for each agent to realize the antagonistic formation motion. A sufficient condition is derived to ensure that all agents make an antagonistic formation motion in a distributed manner. It is shown that all agents can be spontaneously divided into several groups, and agents in the same group collab-orate while agents in different groups compete. Finally, a numerical simulation is included to demonstrate our theoretical results.

  9. On the Formation of Brown Dwarfs

    CERN Document Server

    Jiang, I G; Lin, D N C; Jiang, Ing-Guey

    2004-01-01

    The observational properties of brown dwarfs pose challenges to the theory of star formation. Because their mass is much smaller than the typical Jeans mass of interstellar clouds, brown dwarfs are most likely formed through secondary fragmentation processes, rather than through the direct collapse of a molecular cloud core. In order to prevent substantial post-formation mass accretion, young brown dwarfs must leave the high density formation regions in which they form. We propose here that brown dwarfs are formed in the circumbinary disks. Through post-formation dynamical interaction with their host binary stars, young brown dwarfs are either scattered to large distance or removed, with modest speed, from their cradles.

  10. Processes and problems in secondary star formation

    International Nuclear Information System (INIS)

    Recent developments relating the conditions in molecular clouds to star formation triggered by a prior stellar generation are reviewed. Primary processes are those that lead to the formation of a first stellar generation. The secondary processes that produce stars in response to effects caused by existing stars are compared and evaluated in terms of the observational data presently available. We discuss the role of turbulence to produce clumpy cloud structures and introduce new work on colliding inter-cloud gas flows leading to non-linear inhomogeneous cloud structures in an intially smooth cloud. This clumpy morphology has important consequences for secondary formation. The triggering processes of supernovae, stellar winds, and H II regions are discussed with emphasis on the consequences for radiation driven implosion as a promising secondary star formation mechanism. Detailed two-dimensional, radiation-hydrodynamic calculations of radiation driven implosion are discussed. This mechanism is shown to be highly efficient in synchronizing the formation of new stars in congruent to 1-3 x 104 years and could account for the recent evidence for new massive star formation in several UCHII regions. It is concluded that, while no single theory adequately explains the variety of star formation observed, a uniform description of star formation is likely to involve several secondary processes. Advances in the theory of star formation will require multiple dimensional calculations of coupled processes. The important non-linear interactions include hydrodynamics, radiation transport, and magnetic fields

  11. Heats of formation of binary semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, V.; Sastry, B.S.R. [Department of Electronics and Instrumentation Indian School of Mines, Dhanbad 826 004 (India)

    2005-03-01

    Heats of formation of tetrahedrally coordinated II-VI and III-V groups of binary semiconductors have been calculated using plasmon energy data. Two simple relations between plasmon energy and heats of formation have been proposed. One is based on spectroscopic model of Phillips and Van Vechten and other is based on the best-fit data of heats of formation. The calculated values of heats of formation from both the equations are compared with the experimental values and the values reported by earlier workers. A fairly good agreement has been obtained between them. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  12. A Glimpse at Different File Formats

    Science.gov (United States)

    Shortridge, K.

    2015-09-01

    The image display program AAOGlimpse has recently been extended to provide support for files using both HDF5 and NDF/HDS formats. Loosely defined formats present problems. Given an input file, what should be displayed? A FITS file may contain multiple images, and for the more flexible hierarchical formats things are even less clear: which of the many arrays in a structure actually represents the data of interest? Where is the wavelength or other WCS data? With HDF5 files, this becomes quite complex. This paper describes the way AAOGlimpse handles these questions, and emphasises the importance of agreeing conventions for how file formats are used.

  13. Heating systems for heating subsurface formations

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen, Scott Vinh (Houston, TX); Vinegar, Harold J. (Bellaire, TX)

    2011-04-26

    Methods and systems for heating a subsurface formation are described herein. A heating system for a subsurface formation includes a sealed conduit positioned in an opening in the formation and a heat source. The sealed conduit includes a heat transfer fluid. The heat source provides heat to a portion of the sealed conduit to change phase of the heat transfer fluid from a liquid to a vapor. The vapor in the sealed conduit rises in the sealed conduit, condenses to transfer heat to the formation and returns to the conduit portion as a liquid.

  14. Treating tar sands formations with dolomite

    Energy Technology Data Exchange (ETDEWEB)

    Vinegar, Harold J.; Karanikas, John Michael

    2013-10-15

    A method for treating a karsted formation containing heavy hydrocarbons and dolomite includes providing heat to at least part of one or more karsted layers in the formation from one or more heaters located in the karsted layers. A temperature in at least one of the karsted layers is allowed to reach a decomposition temperature of dolomite in the formation. The dolomite is allowed to decompose and at least some hydrocarbons are produced from at least one of the karsted layers of the formation.

  15. Processes and problems in secondary star formation

    Energy Technology Data Exchange (ETDEWEB)

    Klein, R.I.; Whitaker, R.W.; Sandford M.T. II

    1984-03-01

    Recent developments relating the conditions in molecular clouds to star formation triggered by a prior stellar generation are reviewed. Primary processes are those that lead to the formation of a first stellar generation. The secondary processes that produce stars in response to effects caused by existing stars are compared and evaluated in terms of the observational data presently available. We discuss the role of turbulence to produce clumpy cloud structures and introduce new work on colliding inter-cloud gas flows leading to non-linear inhomogeneous cloud structures in an intially smooth cloud. This clumpy morphology has important consequences for secondary formation. The triggering processes of supernovae, stellar winds, and H II regions are discussed with emphasis on the consequences for radiation driven implosion as a promising secondary star formation mechanism. Detailed two-dimensional, radiation-hydrodynamic calculations of radiation driven implosion are discussed. This mechanism is shown to be highly efficient in synchronizing the formation of new stars in congruent to 1-3 x 10/sup 4/ years and could account for the recent evidence for new massive star formation in several UCHII regions. It is concluded that, while no single theory adequately explains the variety of star formation observed, a uniform description of star formation is likely to involve several secondary processes. Advances in the theory of star formation will require multiple dimensional calculations of coupled processes. The important non-linear interactions include hydrodynamics, radiation transport, and magnetic fields.

  16. Format requirements of thermal neutron scattering data in a nuclear data format to succeed the ENDF format

    Energy Technology Data Exchange (ETDEWEB)

    Brown, D. [Brookhaven National Lab. (BNL), Upton, NY (United States)

    2014-03-31

    In November 2012, the Working Party on Evaluation Cooperation Subgroup 38 (WPEC-SG38) began with the task of developing a nuclear data format and supporting infrastructure to replace the now nearly 50 year old ENDF format. The first step in this process is to develop requirements for the new format and infrastructure. In this talk, I will review the status of ENDF's Thermal Scattering Law (TSL) formats as well as support for this data in the GND format (from which the new format is expected to evolve). Finally, I hope to begin a dialog with members of the thermal neutron scattering community so that their data needs can be accurately and easily accommodated by the new format and tools, as captured by the requirements document. During this discussion, we must keep in mind that the new tools and format must; Support what is in existing data files; Support new things we want to put in data files; and Be flexible enough for us to adapt it to future unanticipated challenges.

  17. Film formation from latex blends

    Science.gov (United States)

    Tang, Jiansheng

    2000-10-01

    Film formation from hard/soft (i.e., high Tg/low Tg) latex blends consisting of hard polystyrene (PS) and soft poly(n-butyl methacrylate-co-n-butyl acrylate) [P(BMA/BA)] latex particles were studied with an emphasis on the influence of the carboxyl groups present on the latex particles. A theoretical model was developed to calculate the optimal surfactant and monomer feed rates for a semicontinuous polymerization process to synthesize monodisperse carboxylated latex particles and independently control the particle size and degree of carboxylation. An important finding obtained from the drying studies is that the drying rate from the edge zone is much faster than the rate obtained from the latex pool. It was also found that the presence of carboxyl groups on the latex particles retarded the drying rate. Utilizing PS particles with a low density of carboxyl groups present on the particle surfaces (e.g., 10% surface coverage) resulted in an even distribution of these particles in the soft copolymer matrix, and thus, good film gloss was achieved. However, the use of hard particles with a high density of carboxyl groups present (e.g., 65% coverage) resulted in a less even distribution of PS particles and poor gloss. A cluster model and a hydrogen bonding mechanism were proposed to explain these phenomena. The presence of the carboxyl groups on the PS particles significantly enhanced the Young's modulus and the yield strength, but did not influence the ultimate mechanical properties. A quantitative model was proposed to predict the Young's modus of the latex blend films as a function of the carboxyl group coverage on the hard particles. There was a good fit between model and the experimental data. The stability of the precipitated calcium carbonate (PCC) particles in the P(BMA/BA) latexes was determined by the charge on pigment surface which, in turn, was influenced by the presence of sodium polyacrylate stabilizer. It was found that the wetting ability of the soft

  18. Formation of parting in quartz

    Science.gov (United States)

    Jørgen Kjøll, Hans; Eske Sørensen, Bjørn

    2014-05-01

    and two, possibly three, planar structures; two evident, one more obscure. The most prominent of the three appears to cut across the recrystallization, offsetting the recrystallization textures with varying distances. We propose a very late formation of the parting due to its crosscutting relationship with all features, such as recrystallized quartz, secondary fluid inclusion trails and twins. The parting develops in crystals that are optimally oriented with respect to σ1 in a fast, low temperature deformation event.

  19. Unit Monitors Manchester-Format Data Buses

    Science.gov (United States)

    Amador, Jose J.

    1994-01-01

    Circuit card converts data signals into convenient hexadecimal form for troubleshooting. Bus-monitoring unit converts data signals from Manchester II format used on data bus into hexadecimal format. Monitoring circuit causes hexadecimal words to display on video terminal, where test engineer compares them with hexadecimal records for troubleshooting. Circuit monitors one bus or two buses simultaneously.

  20. Distributed formation control for autonomous robots

    NARCIS (Netherlands)

    Garcia de Marina Peinado, Hector Jesús

    2016-01-01

    This thesis addresses several theoretical and practical problems related to formation-control of autonomous robots. Formation-control aims to simultaneously accomplish the tasks of forming a desired shape by the robots and controlling their coordinated collective motion. This kind of robot performan

  1. Cadmium Modulates Biofilm Formation by Staphylococcus epidermidis

    NARCIS (Netherlands)

    Wu, Xueqing; Santos, Regiane R.; Fink-Gremmels, Johanna

    2015-01-01

    The aim of the study was to evaluate the effect of cadmium exposure on Staphylococcus epidermidis (ATCC 35984) biofilm formation. Bacteria were cultured in the absence or presence of different concentrations (0-50 mu M) of cadmium. Biofilm formation and bacterial viability were assessed. Quantitativ

  2. Nature and nurture in galaxy formation simulations

    NARCIS (Netherlands)

    Haas, Marcel Richard

    2010-01-01

    We study several aspects of the formation of galaxies, using numerical simulations. We investigate the influence of about thirty different sub-grid physics recipes for cooling, star formation, supernova feedback, AGN feedback etc. on the resulting galaxy populations with large SPH simulations. We in

  3. Formation of communication skills of aviation specialists

    OpenAIRE

    Коваленко, Ольга Олександрівна

    2012-01-01

    Culture of the professional communication is the basis of the professional activity. It is spoken about the process of formation of the professional communication culture, where communication, professionalism of the communication are foundation of it in personal oriented studying by means of creative technologies; examined about peculiarities, and defined conditions of formation of professional oral skills culture of future aviation specialists.

  4. Star formation history in forming dwarf galaxies

    Science.gov (United States)

    Berczik, P.; Kravchuk, S. G.

    The processes of formation and evolution of isolated dwarf galaxies over the Hubble timescale is followed by means of SPH techniques. As an initial protogalaxy perturbation we consider an isolated, uniform, solid -- body rotated sphere involved into the Hubble flow and made of dark and baryonic matter in a 10:1 ratio. The simulations are carried out for the set of models having spin parameters lambda in the range from 0.01 to 0.08 and the total mass of dark matter 1011 M_odot . Our model includes gasdynamics, radiative processes, star formation, supernova feedback and simplified chemistry. The application of modified star formation criterion which accounts for chaotic motions and the time lag between initial development of suitable conditions for star formation and star formation itself (Berczik P.P, Kravchuk S.G. 1997, Ap.Sp.Sci.) provides the realistic description of the process of galaxy formation and evolution. Two parameters: total mass and initial angular momentum of the dwarf protogalaxy play the crucial role in its star formation activity. After the 15 Gyr of the evolution the rapidly rotated dwarf galaxies manifest themselves as an extremly gasrich, heavy element deficient objects showing the initial burst of star formation activity in several spatially separated regions. Slowly rotating objects manifest themselves finally as typical evolved dwarf galaxies.

  5. On the kinetics of platinum silicide formation

    NARCIS (Netherlands)

    Faber, Erik J.; Wolters, Rob A.M.; Schmitz, Jurriaan

    2011-01-01

    In this work, the kinetics of platinum silicide formation for thin Pt films (50 nm) on monocrystalline <100> silicon is investigated via in situ resistance measurements under isothermal (197–275 °C) conditions. For Pt2Si diffusion limited growth was observed. For PtSi formation, however, no linear r

  6. Automatic 3D video format detection

    Science.gov (United States)

    Zhang, Tao; Wang, Zhe; Zhai, Jiefu; Doyen, Didier

    2011-03-01

    Many 3D formats exist and will probably co-exist for a long time even if 3D standards are today under definition. The support for multiple 3D formats will be important for bringing 3D into home. In this paper, we propose a novel and effective method to detect whether a video is a 3D video or not, and to further identify the exact 3D format. First, we present how to detect those 3D formats that encode a pair of stereo images into a single image. The proposed method detects features and establishes correspondences between features in the left and right view images, and applies the statistics from the distribution of the positional differences between corresponding features to detect the existence of a 3D format and to identify the format. Second, we present how to detect the frame sequential 3D format. In the frame sequential 3D format, the feature points are oscillating from frame to frame. Similarly, the proposed method tracks feature points over consecutive frames, computes the positional differences between features, and makes a detection decision based on whether the features are oscillating. Experiments show the effectiveness of our method.

  7. Soft thrombus formation in radiofrequency catheter ablation

    NARCIS (Netherlands)

    Demolin, JM; Eick, OJ; Munch, K; Koullick, E; Nakagawa, H; Wittkampf, FHM

    2002-01-01

    During RF catheter ablation, local temperature elevation can result in coagulum formation on the ablation electrode, resulting in impedance rise. A recent study has also demonstrated the formation of a so-called soft thrombus during experimental ablations. This deposit poorly adhered to the catheter

  8. Problems of Kazakh Literary Criticism Formation

    Directory of Open Access Journals (Sweden)

    Zhandos Smagulov

    2013-01-01

    Full Text Available Тhe article is concerned with the problem of scientific research of Kazakh literature formation in national science. Kazakh literature, having long history of formation is classified by periods. Besides, the article thoroughly considers the principles of the study of methodology, theory, history of spiritual heritage in Kazakh literary criticism

  9. Stone Formation in the Infected Pediatric Enterocystoplasty

    NARCIS (Netherlands)

    R.B. Mathoera (Rejiv)

    2003-01-01

    markdownabstract__Abstract__ Proteus mirabilis is one of the most frequent bacterial agents that can induce infection stone formation by urease production. In recent years the influence of Proteus mirabilis on stone formation in enterocystoplasties has been primarily related to the presence of ure

  10. Learning Progressions that Support Formative Assessment Practices

    Science.gov (United States)

    Alonzo, Alicia C.

    2011-01-01

    Black, Wilson, and Yao (this issue) lay out a comprehensive vision for the way that learning progressions (or other "road maps") might be used to inform and coordinate formative and summative purposes of assessment. As Black, Wilson, and others have been arguing for over a decade, the effective use of formative assessment has great potential to…

  11. Formative Assessment in the High School IMC

    Science.gov (United States)

    Edwards, Valerie A.

    2007-01-01

    In this article, the author discusses how she uses formative assessments of information literacy skills in the high school IMC. As a result of informal observation and conversations with individual students--a form of formative assessment itself--the author learned that students were not using indexes to locate relevant information in nonfiction…

  12. Mechanism of formation of curved Kikuchi lines

    Science.gov (United States)

    Karakhanyan, R. K.; Karakhanyan, K. R.

    2008-07-01

    The mechanism of formation of curved Kikuchi lines, observed at displacement of point reflections from their normal positions, is proposed. Curving of Kikuchi lines is explained taking into account the participation of diffracted electron beams in the formation of Kikuchi electron diffraction patterns.

  13. Pedagogical Formation Education via Distance Education

    Science.gov (United States)

    Ozcan, Deniz; Genc, Zeynep

    2016-01-01

    The purpose of this research is to identify the perceptions of the efficacy of curriculum development on the part of pedagogical formation students, their views regarding their professional attitudes, and their attitudes towards the pedagogical formation education they receive via distance education. The study sample includes 438 Near East…

  14. Lean Data Strategies for Formative Evaluation.

    Science.gov (United States)

    Baker, Eva L.

    The intent of formative evaluation is to improve programs as well as to justify their continuation. It is critical to separate clearly those functions of the evaluation which are political from those which may lead the way to instructional improvement. Data for formative evaluation should be gathered in an interpretable way at the level at which…

  15. Dynamic formation control for autonomous underwater vehicles

    Institute of Scientific and Technical Information of China (English)

    燕雪峰; 古锋; 宋琛; 胡晓琳; 潘毅

    2014-01-01

    Path planning and formation structure forming are two of the most important problems for autonomous underwater vehicles (AUVs) to collaborate with each other. In this work, a dynamic formation model was proposed, in which several algorithms were developed for the complex underwater environment. Dimension changeable particle swarm algorithm was used to find an optimized path by dynamically adjusting the number and the distribution of the path nodes. Position relationship based obstacle avoidance algorithm was designed to detour along the edges of obstacles. Virtual potential point based formation-keeping algorithm was employed by incorporating dynamic strategies which were decided by the current states of the formation. The virtual potential point was used to keep the formation structure when the AUV or the formation was deviated. Simulation results show that an optimal path can be dynamically planned with fewer path nodes and smaller fitness, even with a concave obstacle. It has been also proven that different formation-keeping strategies can be adaptively selected and the formation can change its structure in a narrow area and restore back after passing the obstacle.

  16. Identity formation in the New Testament

    OpenAIRE

    Markus Cromhout

    2009-01-01

    This article is a review of the book entitled Identity Formation in the New Testament (edited by Bengt Holmberg and Mikael Winninge, Mohr Siebeck, Tübingen, 2008). It is a collection of various articles using intertextuality, literary theory (and social identity approaches), gender studies and postcolonial theory when investigating identity formation in the New Testament.

  17. Identity formation in the New Testament

    Directory of Open Access Journals (Sweden)

    Markus Cromhout

    2009-11-01

    Full Text Available This article is a review of the book entitled Identity Formation in the New Testament (edited by Bengt Holmberg and Mikael Winninge, Mohr Siebeck, Tübingen, 2008. It is a collection of various articles using intertextuality, literary theory (and social identity approaches, gender studies and postcolonial theory when investigating identity formation in the New Testament.

  18. An Existentialist Account of Identity Formation.

    Science.gov (United States)

    Bilsker, Dan

    1992-01-01

    Gives account of Marcia's identity formation model in language of existentialist philosophy. Examines parallels between ego-identity and existentialist approaches. Describes identity in terms of existentialist concepts of Heidegger and Sartre. Argues that existentialist account of identity formation has benefits of clarification of difficult…

  19. Chemostratigraphy of Neoproterozoic Banded Iron Formation (BIF)

    DEFF Research Database (Denmark)

    Gaucher, Claudio; Sial, Alcides N.; Frei, Robert

    2015-01-01

    Sawawin BIF (Saudi Arabia), and the Jucurutu Formation of the Seridó Belt (NE Brazil). Lake Superior type BIFs are represented by the Tonian Shilu Group (South China) and the late Ediacaran Arroyo del Soldado Group (Yerbal and Cerro Espuelitas formations, Uruguay). Useful chemostratigraphic tools...

  20. Network Formation under the Threat of Disruption

    NARCIS (Netherlands)

    Hoyer, B.

    2013-01-01

    The studies in this thesis are focused on the impact the presence of a network disruptor has on network formation models. In particular, we build two theoretical models to study the effect of network disruption on network formation and test the effect network disruption has on equilibrium selection

  1. Gas-Phase Infrared; JCAMP Format

    Science.gov (United States)

    SRD 35 NIST/EPA Gas-Phase Infrared; JCAMP Format (PC database for purchase)   This data collection contains 5,228 infrared spectra in the JCAMP-DX (Joint Committee for Atomic and Molecular Physical Data "Data Exchange") format.

  2. Hormonal Regulation of Tuber Formation in Potato

    NARCIS (Netherlands)

    Aksenova, N.P.; Sergeeva, L.; Kolachevskaya, O.O.; Romanov, G.A.

    2013-01-01

    Tubers of potato (Solanum tuberosum L.) plants serve as organs for vegetative propagation and stock of matter and energy for the next generation. Tuber formation is a complex process involving several successive stages: stolon formation and growth, induction of tuberization, tuber initiation and fur

  3. When sticking influences H2 formation

    NARCIS (Netherlands)

    Cazaux, S.; Morisset, S.; Spaans, M.; Allouche, A.

    2011-01-01

    Aims: Because of their catalytic properties, interstellar dust grains are crucial to the formation of H2, the most abundant molecule in the Universe. The formation of molecular hydrogen strongly depends on the ability of H atoms to stick on dust grains. In this study we determine the sticking coeffi

  4. Formative and Summative Assessment in the Classroom

    Science.gov (United States)

    Dixson, Dante D.; Worrell, Frank C.

    2016-01-01

    In this article, we provide brief overviews of the definitions of formative and summative assessment and a few examples of types of formative and summative assessments that can be used in classroom contexts. We highlight the points that these two types of assessment are complementary and the differences between them are often in the way these…

  5. Salicylic acid electrooxidation. A surface film formation

    Energy Technology Data Exchange (ETDEWEB)

    Baturova, M.D.; Vedenjapin, A.; Baturova, M.M. [N.D. Zelinsky Inst. of Organic Chemistry, Russian Academy of Sciences, Moscow (Russian Federation); Weichgrebe, D.; Danilova, E.; Rosenwinkel, K.H. [Univ. of Hannover, Inst. of Water Quality and Waste Management Hannover (Germany); Skundin, A. [A.N. Frumkin Inst. of Electrochemistry, Russian Academy of Sciences, Moscow (Russian Federation)

    2003-07-01

    A possibility to use electrochemical treatment for salicylic acid (SA) removal from waste water was studied. It was found that SA can be oxidized at platinum anode with formation of harmless products. Features of anodic process, in particular, formation of solid film on anode surface as well as properties of the film were investigated. (orig.)

  6. Compressed Multiple-Row Storage Format

    CERN Document Server

    Koza, Zbigniew; Szkoda, Sebastian; Mirosław, Łukasz

    2012-01-01

    A new format for storing sparse matrices is proposed for efficient sparse matrix-vector (SpMV) product calculation on modern throughput-oriented computer architectures. This format extends the standard compressed row storage (CRS) format and is easily convertible to and from it without any memory overhead. Computational performance of an SpMV kernel for the new format is determined for over 140 sparse matrices on two Fermi-class graphics processing units (GPUs) and the efficiency of the kernel, which peaks at 36 and 25 GFLOPS at single and double precision, respectively, is compared with that of five existing generic algorithms and industrial implementations. The efficiency of the new format is also measured as a function of the mean (\\mu) and of the standard deviation (\\sigma) of the number of matrix nonzero elements per row. The largest speedup is found for matrices with \\mu > 20 and \\mu > \\sigma > 1.5 and can be as high as 43%.

  7. Coordinated formation control of multiple nonlinear systems

    Institute of Scientific and Technical Information of China (English)

    Wei KANG; Ning XI; Jindong TAN; Yiwen ZHAO; Yuechao WANG

    2005-01-01

    A general method of controller design is developed for the purpose of formation keeping and reconfiguration of nonlinear systems with multiple subsystems,such as the formation of multiple aircraft,ground vehicles,or robot arms.The model consists of multiple nonlinear systems.Controllers are designed to keep the subsystems in a required formation and to coordinate the subsystems in the presence of environmental changes.A step-by-step algorithm of controller design is developed.Sufficient conditions for the stability of formation tracking are proved.Simulations and experiments are conducted to demonstrate some useful coordination strategies such as movement with a leader,simultaneous movement,series connection of formations,and human-machine interaction.

  8. Storage format for personalized broadcasting content consumption

    Science.gov (United States)

    Jin, Sung Ho; Jang, Jea-Seok; Min, Hyun-Seok; Ro, Yong Man; Kim, Hui Yong

    2007-01-01

    In this paper, we propose a storage format which binds digital broadcasts with related data such as TV-Anytime metadata, additional multimedia resources, and personal viewing history. The goal of the proposed format is to make it possible to offer personalized content consumption after recording broadcasting contents to storage devices, e.g., HD-DVD and Blu-ray Disc. To achieve that, we adopt MPEG-4 file format as a container and apply a binary format for scenes (BIFS) for representing and rendering personal viewing history. In addition, TV-Anytime metadata is used to describe broadcasts and to refer to the additional multimedia resources, e.g, images, audio clips, and short video clips. To demonstrate the usefulness of the proposed format, we introduce an application scenario and test it on that scenario.

  9. On the interplay between star formation and feedback in galaxy formation simulations

    OpenAIRE

    Agertz, Oscar; Kravtsov, Andrey V.

    2014-01-01

    We investigate the star formation-feedback cycle in cosmological galaxy formation simulations, focusing on progenitors of Milky Way (MW)-sized galaxies. We find that in order to reproduce key properties of the MW progenitors, such as semi-empirically derived star formation histories and the shape of rotation curves, our implementation of star formation and stellar feedback requires 1) a combination of local early momentum feedback via radiation pressure and stellar winds and subsequent effici...

  10. Digital forensics formats: seeking a digital preservation storage format for web archiving

    OpenAIRE

    Kim, Y.; Ross, S

    2011-01-01

    In this paper we discuss archival storage formats from the point of view of digital curation and preservation. Considering established approaches to data management as our jumping off point, we selected seven format attributes which are core to the long term accessibility of digital materials. These we have labeled core preservation attributes. These attributes are then used as evaluation criteria to compare file formats belonging to five common categories: formats for archiving s...

  11. PROBA-3: Precise formation flying demonstration mission

    Science.gov (United States)

    Llorente, J. S.; Agenjo, A.; Carrascosa, C.; de Negueruela, C.; Mestreau-Garreau, A.; Cropp, A.; Santovincenzo, A.

    2013-01-01

    Formation Flying (FF) has generated a strong interest in many space applications, most of them involving a significant complexity for building for example on-board large "virtual structures or distributed observatories". The implementation of these complex formation flying missions with critical dependency on this new, advanced and critical formation technology requires a thorough verification of the system behaviour in order to provide enough guarantees for the target mission success. A significant number of conceptual or preliminary designs, analyses, simulations, and HW on-ground testing have been performed during the last years, but still the limitations of the ground verification determine that enough confidence of the behaviour of the formation flying mission will only be possible by demonstration in flight of the concept and the associated technologies. PROBA-3 is the mission under development at ESA for in-flight formation flying demonstration, dedicated to obtain that confidence and the necessary flight maturity level in the formation flying technologies for those future target missions. PROBA-3 will demonstrate technologies such as formation metrology sensors (from very coarse to highest accuracy), formation control and GNC, system operability, safety, etc. During the last years, PROBA-3 has evolved from the initial CDF study at ESA, to two parallel phase A studies, followed by a change in the industrial configuration for the Bridging step between A and B phases. Currently the SRR consolidation has been completed, and the project is in the middle of the phase B. After the phase A study SENER and GMV were responsible for the Formation Flying System, within a mission core team completed by OHB-Sweden, QinetiQ Space and CASA Espacio. In this paper an overview of the PROBA-3 mission is provided, with a more detailed description of the formation flying preliminary design and results.

  12. Star Formation in Henize 206

    Science.gov (United States)

    2004-01-01

    from that explosion impacted a cloud of nearby hydrogen gas, compressed it, and started a new generation of star formation. The death of one star led to the birth of many new stars. This is particularly evident in the MIPS inset, where the 24-micron emission peaks correspond to newly formed stars. The ultraviolet and visible-light photons from the new stars are absorbed by surrounding dust and re-radiated at longer infrared wavelengths, where it is detected by Spitzer. This emission nebula was cataloged by Karl Henize (HEN-eyes) while spending 1948-1951 in South Africa doing research for his Ph.D. dissertation at the University of Michigan. Henize later became a NASA astronaut and, at age 59, became the oldest rookie to fly on the Space Shuttle during an eight-day flight of the Challenger in 1985. He died just short of his 67th birthday in 1993 while attempting to climb the north face of Mount Everest, the world's highest peak.

  13. MAGNETIC FIELDS AND GALACTIC STAR FORMATION RATES

    International Nuclear Information System (INIS)

    The regulation of galactic-scale star formation rates (SFRs) is a basic problem for theories of galaxy formation and evolution: which processes are responsible for making observed star formation rates so inefficient compared to maximal rates of gas content divided by dynamical timescale? Here we study the effect of magnetic fields of different strengths on the evolution of giant molecular clouds (GMCs) within a kiloparsec patch of a disk galaxy and resolving scales down to ≃0.5 pc. Including an empirically motivated prescription for star formation from dense gas (nH>105 cm−3) at an efficiency of 2% per local free-fall time, we derive the amount of suppression of star formation by magnetic fields compared to the nonmagnetized case. We find GMC fragmentation, dense clump formation, and SFR can be significantly affected by the inclusion of magnetic fields, especially in our strongest investigated B-field case of 80 μG. However, our chosen kiloparsec-scale region, extracted from a global galaxy simulation, happens to contain a starbursting cloud complex that is only modestly affected by these magnetic fields and likely requires internal star formation feedback to regulate its SFR

  14. What triggers star formation in galaxies?

    CERN Document Server

    Elmegreen, Bruce G

    2012-01-01

    Processes that promote the formation of dense cold clouds in the interstellar media of galaxies are reviewed. Those that involve background stellar mass include two-fluid instabilities, spiral density wave shocking, and bar accretion. Young stellar pressures trigger gas accumulation on the periphery of cleared cavities, which often take the form of rings by the time new stars form. Stellar pressures also trigger star formation in bright-rim structures, directly squeezing the pre-existing clumps in nearby clouds and clearing out the lower density gas between them. Observations of these processes are common. How they fit into the empirical star formation laws, which relate the star formation rate primarily to the gas density, is unclear. Most likely, star formation follows directly from the formation of cold dense gas, whatever the origin of that gas. If the average pressure from the weight of the gas layer is large enough to produce a high molecular fraction in the ambient medium, then star formation should fo...

  15. Inviscid Analysis of Extended Formation Flight

    Science.gov (United States)

    Kless, James; Aftosmis, Michael J.; Ning, Simeon Andrew; Nemec, Marian

    2012-01-01

    Flying airplanes in extended formations, with separation distances of tens of wingspans, significantly improves safety while maintaining most of the fuel savings achieved in close formations. The present study investigates the impact of roll trim and compressibility at fixed lift coefficient on the benefits of extended formation flight. An Euler solver with adjoint-based mesh refinement combined with a wake propagation model is used to analyze a two-body echelon formation at a separation distance of 30 spans. Two geometries are examined: a simple wing and a wing-body geometry. Energy savings, quantified by both formation drag fraction and span efficiency factor, are investigated at subsonic and transonic speeds for a matrix of vortex locations. The results show that at fixed lift and trimmed for roll, the optimal location of vortex impingement is about 10% inboard of the trailing airplane s wing-tip. Interestingly, early results show the variation in drag fraction reduction is small in the neighborhood of the optimal position. Over 90% of energy benefits can be obtained with a 5% variation in transverse and 10% variation in crossflow directions. Early results suggest control surface deflections required to achieve trim reduce the benefits of formation flight by 3-5% at subsonic speeds. The final paper will include transonic effects and trim on extended formation flight drag benefits.

  16. Influence of fluorosurfactants on hydrate formation rates

    Energy Technology Data Exchange (ETDEWEB)

    Kim, C.U.; Jeong, K.E.; Chae, H.J.; Jeong, S.Y. [Korea Reasearch Inst. of Chemical Technology, Alternative Chemicals/Fuel Research Center, Yuseong-Gu, Daejon (Korea, Republic of)

    2008-07-01

    Gas hydrates, or clathrates, are ice-like solids that forms when natural gas is in contact with liquid water or ice under high pressure and low temperature. There is significant interest in studying the storage and transportation of gas in the form of hydrates. However, a critical problem impacting the industrial application of gas hydrates for storage and transportation of natural gas is the slow formation rate of natural gas hydrate. Researchers have previously reported on the promotion effect of some additives on gas hydrate formation and hydrate gas content. Fluorosurfactants are significantly superior to nonfluorinated surfactants in wetting action, as well as stability in harsh environments, both thermal and chemical. This paper discussed an experimental investigation into the effects of fluorosurfactants with different ionic types on the formation of methane hydrate. The surfactants used were FSN-100 of DuPont Zonyl as non-ionic surfactant and FC-143 of DuPont as anionic surfactant. The paper discussed the experimental apparatus for methane hydrate formation. It also discussed hydrate formation kinetics and the series of hydrate formation experiments that were conducted in the presence of fluorosurfactants. Last, the paper explored the results of the study. It was concluded that anionic fluorosurfactant of FC-143 had a better promoting effect on methane hydrate formation compared with nonionic surfactant of FSN-100. 8 refs., 2 tabs., 2 figs.

  17. Formation Feedback Applied to Behavior-Based Approach to Formation Keeping

    Institute of Scientific and Technical Information of China (English)

    苏治宝; 陆际联

    2004-01-01

    Approaches to the study of formation keeping for multiple mobile robots are analyzed and a behavior-based robot model is built in this paper. And, a kind of coordination architecture is presented, which is similar to the infantry squad organization and is used to realize multiple mobile robots to keep formations. Simulations verify the validity of the approach to keep formation, which combines the behavior-based method and formation feedback. The effects of formation feedback on the performance of the system are analyzed.

  18. Star Formation Histories of the Galactic Satellites

    CERN Document Server

    Gilmore, G; Valls-Gabaud, D; Gilmore, Gerard; Hernandez, Xavier; Valls-Gabaud, David

    1999-01-01

    Late accretion models for formation of the Galactic halo require that many Galactic satellite galaxies have been cannibalised into the halo field. Comparison of the metallicity and age distribution function of stars in the surviving satellites with the apparently exclusively old stars in the field halo can constrain the importance of any such process. We have developed a new objective technique to determine star formation histories in dSph galaxies. We apply this technique to the surviving Galactic satellites, deducing an approximately uniform distribution of ages for the constituents, quite unlike the halo field stars. Thus, late accretion did not play a substantial part in Galactic halo formation.

  19. The formation of compact groups of galaxies

    Institute of Scientific and Technical Information of China (English)

    马駬; 俞允强

    1999-01-01

    In the compact group of galaxies the galaxies can merge into a few massive ones in a very short time, so they must be formed very recently. On the other hand, according to the theory of structure formation, the denser system should form earlier. By analyzing the apparent paradox, we suggest that the merging process of CDM halo plays an important role in the formation of the compact groups of galaxies: it delays the formation of compact groups of galaxies, and makes the groups of galaxies much denser.

  20. Geologic formation prospect of uranium Irian Jaya

    International Nuclear Information System (INIS)

    This paper was resulted from compilation of regional geologic mapping and uranium prospection in which it was considered in making exploration program. Method used was literary study of geologic information which was connected with uranium deposit occurrence. From the 26 formations identified as a formation based on physical characteristics and U grade in stream sediments and rocks, there were 2 specific formation groups which were good enough to be dealt in exploration program that is Kemblangan Group and Aifam Group. (author); 8 refs; 4 figs

  1. Metonymy and word-formation revisited

    OpenAIRE

    Janda, Laura Alexis

    2014-01-01

    Brdar and Brdar-Szabó (this volume) offer a critique of Janda (2011). Janda (2011) found that the same cognitive strategy that facilitates metonymy, namely use of a conceptual source to access a target, can also be invoked in many patterns of affixal word-formation. In other words, many cases of word-formation appear to be motivated by metonymic association. Brdar and Brdar-Szabó claim that it is incorrect to refer to word-formational processes as metonymies. In addition to the robust paralle...

  2. Radiation Driven Implosion and Triggered Star Formation

    CERN Document Server

    Bisbas, T G; Wünsch, R; Hubber, D A; Walch, S

    2010-01-01

    We present simulations of initially stable isothermal clouds exposed to ionizing radiation from a discrete external source, and identify the conditions that lead to radiatively driven implosion and star formation. We use the Smoothed Particle Hydrodynamics code SEREN (Hubber et al. 2010) and the HEALPix-based photoionization algorithm described in Bisbas et al. (2009). We find that the incident ionizing flux is the critical parameter determining the evolution: high fluxes simply disperse the cloud, whereas low fluxes trigger star formation. We find a clear connection between the intensity of the incident flux and the parameters of star formation.

  3. Subjectivities as Centers of Citizen Formation

    Directory of Open Access Journals (Sweden)

    ANGÉLICA MARÍA OCAMPO-TALERO

    2008-12-01

    Full Text Available The article presents academic reflections resulting from the teaching work of the authors with students of the Psychology career at the Javeriana University.Beginning from Latinamerica’s sociopolitical reality, it is pointed out that complex views of citizenship are needed that permit the confrontation of the region’s crises, particularly in Colombia, from the educational scenarios. Formative implications of that view for the professional work of Psychologists are reviewed, proposing subject and subjectivity as the heart of formative practices. Finally, some significant challenges to the Psychologists’ task inthe field of civic formation in educational contexts are outlined.

  4. Turbulence, Feedback, and Slow Star Formation

    OpenAIRE

    Krumholz, Mark R.

    2006-01-01

    One of the outstanding puzzles about star formation is why it proceeds so slowly. Giant molecular clouds convert only a few percent of their gas into stars per free-fall time, and recent observations show that this low star formation rate is essentially constant over a range of scales from individual cluster-forming molecular clumps in the Milky Way to entire starburst galaxies. This striking result is perhaps the most basic fact that any theory of star formation must explain. I argue that a ...

  5. Extrasolar planets formation, detection and dynamics

    CERN Document Server

    Dvorak, Rudolf

    2008-01-01

    This latest, up-to-date resource for research on extrasolar planets covers formation, dynamics, atmospheres and detection. After a look at the formation of giant planets, the book goes on to discuss the formation and dynamics of planets in resonances, planets in double stars, atmospheres and habitable zones, detection via spectra and transits, and the history and prospects of ESPs as well as satellite projects.Edited by a renowned expert in solar system dynamics with chapters written by the leading experts in the method described -- from the US and Europe -- this is an ideal textbook for g

  6. File format for storage of scalable video

    Institute of Scientific and Technical Information of China (English)

    BAI Gang; SUN Xiao-yan; WU Feng; YIN Bao-cai; LI Shi-peng

    2006-01-01

    A file format for storage of scalable video is proposed in this paper. A generic model is presented to enable a codec independent description of scalable video stream. The relationships, especially the dependencies, among sub-streams in a scalable video stream are specified sufficiently and effectively in the proposed model. Complying with the presented scalable video stream model, the file format for scalable video is proposed based on ISO Base Media File Format, which is simple and flexible enough to address the demands of scalable video application as well as the non-scalable ones.

  7. Binary Modulation Formats in Optical Access Networks

    Directory of Open Access Journals (Sweden)

    Vladimir Tejkal

    2010-01-01

    Full Text Available In this paper the binary modulation formats and their application in passive optical networks have been discussed. Passive optical networks are characterized by dividing the optical signal between several end users by using passive splitters, which added a significant attenuation to the network. The performance of the selected modulation formats, depending on the transmitter power in order to verify that there is no signal distortion, has been examined in our simulations. A minimal error rate of the system for each modulation format has been also examined. Finding a suitable modulation, which would allow extension of the distance and splitting ration in current passive optical networks, has been the main aim.

  8. Spur Reaction Model of Positronium Formation

    DEFF Research Database (Denmark)

    Mogensen, O. E.

    1974-01-01

    A new model of positronium (Ps) formation is proposed. Positronium is assumed to be formed by a reaction between a positron and an electron in the positron spur. Ps formation must compete with electron‐ion recombination and electron or positron reactions with solvent molecules and scavenger...... impurities. It is also influenced by electron and positron solvation. The model correlates the measured Ps formation probabilities with the spur electron properties determined in radiation chemistry. The predictions of the model are shown to be in good agreement with experimental results for liquids and...

  9. Biofilm formation in a hot water system

    DEFF Research Database (Denmark)

    Bagh, L.K.; Albrechtsen, Hans-Jørgen; Arvin, Erik;

    2002-01-01

    The biofilm formation rate was measured in situ in a hot water system in an apartment building by specially designed sampling equipment, and the net growth of the suspended bacteria was measured by incubation of water samples with the indigeneous bacteria. The biofilm formation rate reached......, in the sludge, or in the water from the distribution system was negligible. This indicated that bacterial growth took place on the inner surfaces in the hot water system and biofilm formation and detachment of bacteria could account for most of the suspended bacteria actually measured in hot water. Therefore...

  10. Star Formation Regions in LDN 1667

    Science.gov (United States)

    Gyulbudaghian, A. L.

    2015-09-01

    A group of three star formation regions in the dark cloud LDN 1667 is examined. All three of these regions contain Trapezium type systems. 12C(1-0) observations are made of the part of the molecular cloud LDN 1667 associated with one of the star formation regions. Three molecular clouds were detected, one of which (the main cloud) has a red and a blue outflow. Three stars from the star formation regions are found to have annular nebulae and one star has a conical nebula. The dark cloud LDN 1667 is associated with a radial system of dark globules which is formed by the star HD 57061.

  11. Collective Identity Formation in Hybrid Organizations

    DEFF Research Database (Denmark)

    Boulongne, Romain; Boxenbaum, Eva

    The present article examines the process of collective identity formation in the context of hybrid organizing. Empirically, we investigate hybrid organizing in a collaborative structure at the interface of two heterogeneous organizations in the domain of new renewable energies. We draw...... organizations. Our findings point to two factors that limit knowledge sharing and hence to new collective identity formation in a hybrid space: 1) ambiguous or multiple organizational roles and 2) strong identities of the collaborating organizations. These findings contribute to illuminating the initial...... formation of a new collective identity in hybrid organizing, and hence how new hybrid organizational forms may emerge non-intentionally....

  12. Mechanically loaded myotubes affect osteoclast formation

    NARCIS (Netherlands)

    P. Juffer; R.T. Jaspers; J. Klein-Nulend; A.D. Bakker

    2014-01-01

    In response to mechanical loading skeletal muscle produces numerous growth factors and cytokines that enter the circulation. We hypothesized that myotubes produce soluble factors that affect osteoclast formation and aimed to identify which osteoclastogenesis-modulating factors are differentially pro

  13. Kinetic exchange models for social opinion formation

    CERN Document Server

    Lallouache, Mehdi; Chakrabarti, Bikas K

    2010-01-01

    We propose a minimal model for the collective dynamics of opinion formation in the society, by modifying kinetic exchange dynamics studied in the context of income, money or wealth distributions in a society.

  14. Non-Specialized File Format Extension

    Directory of Open Access Journals (Sweden)

    Blake W. Ford & Khosrow Kaikhah

    2011-12-01

    Full Text Available The study expands upon previous work in format extension. The initial research purposed extraspace provided by an unrefined format to store metadata about the file in question. This processdoes not negatively impact the original intent of the format and allows for the creation of newderivative file types with both backwards compatibility and new features. The file format extensionalgorithm has been rewritten entirely in C++ and is now being distributed as an open sourceC/C++ static library, roughdraftlib. The files from our previous research are essentially binarycompatible though a few extra fields have been added for developer convenience. The new datarepresents the current and oldest compatible versions of the binary and values representing thescaling ratio of the image. These new fields are statically included in every file and take only afew bytes to encode, so they have a trivial effect on the overall encoding density.

  15. Black Hole Formation at the Correspondence Point

    CERN Document Server

    Iizuka, Norihiro; Roy, Shubho; Sarkar, Debajyoti

    2013-01-01

    We study the process of bound state formation in a D-brane collision. We consider two mechanisms for bound state formation. The first, operative at weak coupling in the worldvolume gauge theory, is pair creation of W-bosons. The second, operative at strong coupling, corresponds to formation of a large black hole in the dual supergravity. These two processes agree qualitatively at intermediate coupling, in accord with the correspondence principle of Horowitz and Polchinski. We show that the size of the bound state and timescale for formation of a bound state agree at the correspondence point. The timescale involves matching a parametric resonance in the gauge theory to a quasinormal mode in supergravity.

  16. Multi-Agent Formations and Sensor Networks

    NARCIS (Netherlands)

    Cao, M.

    2007-01-01

    We investigate three intertwined problems concerned with distributed cooperative control of groups of autonomous mobile agents. These problems are the consensus problem in mobile networks, the localization problem in sensor networks and the formation maintenance problem in autonomous robotic teams.

  17. Nanoparticles from the gasphase formation, structure, properties

    CERN Document Server

    Lorke, Axel; Schmechel, Roland; Schulz, Christof

    2012-01-01

    This book offers a broad overview of the complete production and value chain from nanoparticle formation to integration in products and devices, and offers deep insight into the fabrication, characterization and application of nanoparticles from the gasphase.

  18. Star formation: Sibling rivalry begins at birth

    Science.gov (United States)

    Kratter, Kaitlin M.

    2015-02-01

    High-resolution astronomical observations of a nearby molecular gas cloud have revealed a quadruplet of stars in the act of formation. The system is arguably the youngest multiple star system detected so far. See Letter p.213

  19. Antagonistic formation motion of cooperative agents

    Science.gov (United States)

    Lu, Wan-Ting; Dai, Ming-Xiang; Xue, Fang-Zheng

    2015-02-01

    This paper investigates a new formation motion problem of a class of first-order multi-agent systems with antagonistic interactions. A distributed formation control algorithm is proposed for each agent to realize the antagonistic formation motion. A sufficient condition is derived to ensure that all of the agents make an antagonistic formation motion in a distributed manner. It is shown that all of the agents can be spontaneously divided into several groups and that agents in the same group collaborate while agents in different groups compete. Finally, a numerical simulation is included to demonstrate our theoretical results. Project supported by the National Natural Science Foundation of China (Grant Nos. 61203080 and 61473051) and the Natural Science Foundation of Chongqing City (Grant No. CSTC 2011BB0081).

  20. MP3 the meaning of a format

    CERN Document Server

    Sterne, Jonathan

    2012-01-01

    Jonathan Sterne shows that understanding the historical meaning of the MP3, the world's most common format for recorded audio, involves rethinking the place of digital technologies in the broader universe of twentieth-century communication history.

  1. On the Formation of Brown Dwarfs

    CERN Document Server

    Jiang, I G; Lin, D N C; Jiang, Ing-Guey

    2006-01-01

    The observational properties of brown dwarfs pose challenges to the theory of star formation. Because their mass is much smaller than the typical Jeans mass of interstellar clouds, brown dwarfs are most likely formed through secondary fragmentation processes, rather than through the direct collapse of a molecular cloud core. In order to prevent substantial post-formation mass accretion, young brown dwarfs must leave the high density formation regions in which they form. We propose here that brown dwarfs are formed in the optically thin outer regions of circumbinary disks. Through post-formation dynamical interaction with their host binary stars, young brown dwarfs are either scattered to large distance or removed, with modest speed, from their cradles.

  2. Dynamics of sheet nacre formation in bivalves.

    Science.gov (United States)

    Rousseau, Marthe; Meibom, Anders; Gèze, Marc; Bourrat, Xavier; Angellier, Martine; Lopez, Evelyne

    2009-03-01

    Formation of nacre (mother-of-pearl) is a biomineralization process of fundamental scientific as well as industrial importance. However, the dynamics of the formation process is still not understood. Here, we use scanning electron microscopy and high spatial resolution ion microprobe depth-profiling to image the full three-dimensional distribution of organic materials around individual tablets in the top-most layer of forming nacre in bivalves. Nacre formation proceeds by lateral, symmetric growth of individual tablets mediated by a growth-ring rich in organics, in which aragonite crystallizes from amorphous precursors. The pivotal role in nacre formation played by the growth-ring structure documented in this study adds further complexity to a highly dynamical biomineralization process.

  3. Propane Clathrate Hydrate Formation Accelerated by Methanol.

    Science.gov (United States)

    Amtawong, Jaruwan; Guo, Jin; Hale, Jared S; Sengupta, Suvrajit; Fleischer, Everly B; Martin, Rachel W; Janda, Kenneth C

    2016-07-01

    The role of methanol as both an inhibitor and a catalyst for the formation of clathrate hydrates (CHs) has been a topic of intense study. We report a new quantitative study of the kinetics of propane CH formation at 253 K from the reaction of propane gas with ice particles that have been doped with varying amounts of methanol. We find that methanol significantly accelerates the formation reaction with quite small doping quantities. Even for only 1 methanol molecule per 10 000 water molecules, the maximum uptake rate of propane into CHs is enhanced and the initiation pressure is reduced. These results enable more efficient production of CHs for gas storage. This remarkable acceleration of the CH formation reaction by small quantities of methanol may place constraints on the mechanism of the inhibition effect observed under other conditions, usually employing much larger quantities of methanol. PMID:27275862

  4. Promoting proximal formative assessment with relational discourse

    Science.gov (United States)

    Scherr, Rachel E.; Close, Hunter G.; McKagan, Sarah B.

    2012-02-01

    The practice of proximal formative assessment - the continual, responsive attention to students' developing understanding as it is expressed in real time - depends on students' sharing their ideas with instructors and on teachers' attending to them. Rogerian psychology presents an account of the conditions under which proximal formative assessment may be promoted or inhibited: (1) Normal classroom conditions, characterized by evaluation and attention to learning targets, may present threats to students' sense of their own competence and value, causing them to conceal their ideas and reducing the potential for proximal formative assessment. (2) In contrast, discourse patterns characterized by positive anticipation and attention to learner ideas increase the potential for proximal formative assessment and promote self-directed learning. We present an analysis methodology based on these principles and demonstrate its utility for understanding episodes of university physics instruction.

  5. Physics of star formation in galaxies

    CERN Document Server

    Palla, F

    2002-01-01

    Begining with a historical introduction, ""Star Formation: The Early History"", this text then presents two long articles on ""Pre-Main-Sequence Evolution of Stars and Young Clusters"" and ""Observations of Young Stellar Objects"".

  6. The formation of planets by disc fragmentation

    Directory of Open Access Journals (Sweden)

    Stamatellos Dimitris

    2013-04-01

    Full Text Available I discuss the role that disc fragmentation plays in the formation of gas giant and terrestrial planets, and how this relates to the formation of brown dwarfs and low-mass stars, and ultimately to the process of star formation. Protostellar discs may fragment, if they are massive enough and can cool fast enough, but most of the objects that form by fragmentation are brown dwarfs. It may be possible that planets also form, if the mass growth of a proto-fragment is stopped (e.g. if this fragment is ejected from the disc, or suppressed and even reversed (e.g by tidal stripping. I will discuss if it is possible to distinguish whether a planet has formed by disc fragmentation or core accretion, and mention of a few examples of observed exoplanets that are suggestive of formation by disc fragmentation.

  7. Delayed quarkonium formation in a magnetic field

    CERN Document Server

    Suzuki, Kei

    2016-01-01

    Formation time of heavy quarkonia in a homogeneous magnetic field is analyzed by using a phenomenological ansatz of the vector current correlator. Because the existence of a magnetic field mixes vector quarkonia ($J/\\psi$, $\\psi^\\prime$) and their pseudoscalar partners ($\\eta_c$, $\\eta_c^\\prime$), the properties of the quarkonia can be modified through such a spin mixing. This means that the formation time of quarkonia is also changed by the magnetic field. We show the formation time of vector quarkonia is delayed by an idealized constant magnetic field, where the formation time of the excited state becomes longer than that of the ground state. As a more realistic situation in heavy-ion collisions, effects by a time-dependent magnetic field are also discussed.

  8. Mechanisms and Geochemical Models of Core Formation

    CERN Document Server

    Rubie, David C

    2015-01-01

    The formation of the Earth's core is a consequence of planetary accretion and processes in the Earth's interior. The mechanical process of planetary differentiation is likely to occur in large, if not global, magma oceans created by the collisions of planetary embryos. Metal-silicate segregation in magma oceans occurs rapidly and efficiently unlike grain scale percolation according to laboratory experiments and calculations. Geochemical models of the core formation process as planetary accretion proceeds are becoming increasingly realistic. Single stage and continuous core formation models have evolved into multi-stage models that are couple to the output of dynamical models of the giant impact phase of planet formation. The models that are most successful in matching the chemical composition of the Earth's mantle, based on experimentally-derived element partition coefficients, show that the temperature and pressure of metal-silicate equilibration must increase as a function of time and mass accreted and so m...

  9. 4 dnja v drugom formate / Dmitri Babitshenko

    Index Scriptorium Estoniae

    Babitshenko, Dmitri

    2007-01-01

    25.-28. okt. Teises Teatris toimuvast festivalist "Teine formaat 2. Sügishooaeg" (Drugoi format 2), mille programmis on muusikat, teatrietendusi, luulet, tantsulavastusi ja filme. Festivali organiseerija on Teise Teatri administraator Anastassia Kulkova

  10. Quark Matter Droplet Formation in Neutron Stars

    OpenAIRE

    Heiselberg, H.

    1995-01-01

    The formation rate of quark matter droplets in neutron stars is calculated from a combination of bubble formation rates in cold degenerate and high temperature matter. Nuclear matter calculations of the viscosity and thermal conductivity are applied. Results show that droplets form only in the core of neutron stars shortly after supernova collapse, where pressures and temperatures are high, and for sufficiently small interface tension between nuclear and quark matter. Coulomb energies hinder ...

  11. Protein folding guides disulfide bond formation

    OpenAIRE

    Qin, Meng; Wang, Wei; Thirumalai, D.

    2015-01-01

    Anfinsen inferred the principles of protein folding by studying a protein containing four disulfide bonds in the native state. However, how protein folding drives disulfide bond formation is poorly understood despite the role such proteins play in variety of extracellular and intracellular functions. We developed a method to mimic the complex chemistry of disulfide bond formation in molecular simulations, which is used to decipher the mechanism of folding of bovine pancreatic trypsin inhibito...

  12. Shedding light on disulfide bond formation

    DEFF Research Database (Denmark)

    Ostergaard, H; Henriksen, A; Hansen, F G;

    2001-01-01

    To visualize the formation of disulfide bonds in living cells, a pair of redox-active cysteines was introduced into the yellow fluorescent variant of green fluorescent protein. Formation of a disulfide bond between the two cysteines was fully reversible and resulted in a >2-fold decrease in the i...... for redox-active cysteines. In the cytoplasm of Escherichia coli, the protein was a sensitive probe for the redox changes that occur upon disruption of the thioredoxin reductive pathway....

  13. Primordial black hole formation from cosmological fluctuations

    CERN Document Server

    Harada, Tomohiro

    2016-01-01

    Primordial black holes (PBHs) are those which may have formed in the early Universe and affected the subsequent evolution of the Universe through their Hawking radiation and gravitational field. To constrain the early Universe from the observational constraint on the abundance of PBHs, it is essential to determine the formation threshold for primordial cosmological fluctuations, which are naturally described by cosmological long-wavelength solutions. I will briefly review our recent analytical and numerical results on the PBH formation.

  14. MARC Formats in China: Local or International?

    Directory of Open Access Journals (Sweden)

    Ben Gu

    2014-01-01

    Full Text Available The application of MARC formats in Chinese libraries has a history of about 20 years. At the age of internationalization and digitization, people ask the question: why we chose UNIMARC for the basis of CNMARC? Is it the best choice for China? Are there any other options? In this paper, the author reviews many historical documents and analyzes the present status of MARC formats in China.

  15. SMEs need formative infrastructure for business transformation

    OpenAIRE

    Gäre, Klas; Melin, Ulf

    2011-01-01

    Purpose – The purpose is to study conditions for ICT-use in SMEs, actors and roles involved and concepts constituting a formative infrastructure. Method - The methodological point of departure and approach in this study is qualitative and more than 60 interviews are performed within a geographical region. Findings – Important findings from the present research is a formative ICT infrastructure can be viewed as constituted by identified needs among SMEs, in (1) sensemaking, (2) sensegiving, an...

  16. Elucidating severe urban haze formation in China

    OpenAIRE

    Guo, Song; Hu, Min; Zamora, Misti L.; Peng, Jianfei; Shang, Dongjie; Zheng, Jing; Du, Zhuofei; Wu, Zhijun; Shao, Min; Zeng, Limin; Molina, Mario J.; Zhang, Renyi

    2014-01-01

    We illustrate the similarity and difference in particulate matter (PM) formation between Beijing and other world regions. The periodic cycle of PM events in Beijing is regulated by meteorological conditions. While the particle chemical compositions in Beijing are similar to those commonly measured worldwide, efficient nucleation and growth over an extended period in Beijing are distinctive from the aerosol formation typically observed in other global areas. Gaseous emissions of volatile organ...

  17. Formation and development of sperms in angiosperms

    OpenAIRE

    S. Tatintseva

    2014-01-01

    Spermiogelnesis has been studied in a large number of Angiosperm species characterizing different levels of phylogenetic system. The formation and development of male gamets can be described as formation of sperm cells that undergo ontogenesis which stimulates changes up to full maturity of the pollen grain. The process of ontogenesis is aimed at creating a suitable delivery system by the pollen tube to a female gamete.

  18. Remarks on Rapid vs. Slow Star Formation

    OpenAIRE

    Javier Ballesteros-Paredes; Lee Hartmann

    2006-01-01

    We discuss problems with some observational estimates indicating long protostellar core lifetimes and large stellar age spreads in molecular clouds. We also point out some additional observational constraints which suggest that protostellar cores do not have long lifetimes before collapsing. For external galaxies, we argue that the widths of spiral arms does not imply a long star-formation process, since the formation of massive stars will disrupt molecular clouds, move material around, compr...

  19. Crenarchaeal Biofilm Formation under Extreme Conditions

    OpenAIRE

    Andrea Koerdt; Julia Gödeke; Jürgen Berger; Thormann, Kai M.; Sonja-Verena Albers

    2010-01-01

    BACKGROUND: Biofilm formation has been studied in much detail for a variety of bacterial species, as it plays a major role in the pathogenicity of bacteria. However, only limited information is available for the development of archaeal communities that are frequently found in many natural environments. METHODOLOGY: We have analyzed biofilm formation in three closely related hyperthermophilic crenarchaeotes: Sulfolobus acidocaldarius, S. solfataricus and S. tokodaii. We established a microtitr...

  20. Rapid Formation of Ice Giant Planets

    CERN Document Server

    Boss, A P; Haghighipour, N; Boss, Alan P.; Wetherill, George W.; Haghighipour, Nader

    2002-01-01

    The existence of Uranus and Neptune presents severe difficulties for the core accretion model for the formation of ice giant planets. We suggest an alternative mechanism, namely disk instability leading to the formation of gas giant protoplanets, coagulation and settling of dust grains to form ice/rock cores at their centers, and photoevaporation of their gaseous envelopes by a nearby OB star, as a possible means of forming ice giant planets.

  1. Social educators's professional competence formation under supervision

    OpenAIRE

    Truskovska, Ženija

    2013-01-01

    ABSTRACT The objective of the doctoral thesis: justify theoretically the essence of the social educator’s professional competence and the structure of its formation, to elaborate and examine within an empirical research the structural content and conceptual models of social educator’s professional competence as a readiness for professional activity development under supervision. In the research the problems of professional formation of the prospective social educators are analyzed, pro...

  2. Physics of Structure Formation in the Universe

    OpenAIRE

    Choudhury, T. Roy

    2003-01-01

    In recent years, unprecedented progress in observational cosmology has revealed a great deal of information about the formation and evolution of structures in the universe. This, in turn, has raised many challenging issues for the theorists. In the thesis, we have addressed two such key issues, namely, (a) the formation of baryonic structures and (b) the nature of dark matter and dark energy and the limitations in determining their nature from observations. The main results from the thesis ar...

  3. Massive Star Formation: The Power of Interferometry

    OpenAIRE

    beuther, Henrik

    2007-01-01

    This article presents recent work to constrain the physical and chemical properties in high-mass star formation based largely on interferometric high-spatial-resolution continuum and spectral line studies at (sub)mm wavelengths. After outlining the concepts, potential observational tests, a proposed evolutionary sequence and different possible definitions for massive protostars, four particular topics are highlighted: (a) What are the physical conditions at the onset of massive star formation...

  4. Pattern Formation by Competition: A Biological Example

    OpenAIRE

    M. Bezzi; Ciliberto, A.; A.Mengoni

    1999-01-01

    We present a simple model based on a reaction-diffusion equation to explain pattern formation in a multicellular bacterium (Streptomyces). We assume competition for resources as the basic mechanism that leads to pattern formation; in particular we are able to reproduce the spatial pattern formed by bacterial aerial mycelium in the case of growth in minimal (low resources) and maximal (large resources) culture media.

  5. Quinstant Dark Energy Predictions for Structure Formation

    CERN Document Server

    Nodal, Yoelsy Leyva; Cardone, V F

    2009-01-01

    We explore the predictions of a class of dark energy models, quinstant dark energy, concerning the structure formation in the Universe, both in the linear and non-linear regimes. Quinstant dark energy is considered to be formed by quintessence and a negative cosmological constant. We conclude that these models give good predictions for structure formation in the linear regime, but fail to do so in the non-linear one, for redshifts larger than one.

  6. The Degeneracy of Galaxy Formation Models

    OpenAIRE

    Neistein, Eyal; Weinmann, Simone M.

    2009-01-01

    We develop a new formalism for modeling the formation and evolution of galaxies within a hierarchical universe. Similarly to standard semi-analytical models we trace galaxies inside dark-matter merger-trees. The formalism includes treatment of feedback, star-formation, cooling, smooth accretion, gas stripping in satellite galaxies, and merger-induced star bursts. However, unlike in other models, each process is assumed to have an efficiency which depends only on the host halo mass and redshif...

  7. Structure and formation of ant transportation networks

    OpenAIRE

    Latty, Tanya; Ramsch, Kai; Ito, Kentaro; Nakagaki, Toshiyuki; Sumpter, David J. T.; Middendorf, Martin; Beekman, Madeleine

    2011-01-01

    Many biological systems use extensive networks for the transport of resources and information. Ants are no exception. How do biological systems achieve efficient transportation networks in the absence of centralized control and without global knowledge of the environment? Here, we address this question by studying the formation and properties of inter-nest transportation networks in the Argentine ant (Linepithema humile). We find that the formation of inter-nest networks depends on the number...

  8. Formation of Nitrous Acid on Urban Surfaces

    OpenAIRE

    Trick, Sebastian

    2004-01-01

    Nitrous acid (HONO) has been observed in the nocturnal urban atmosphere for decades. During daylight hours, the rapid photolysis of HONO is a significant source of OH-radicals, which drive tropospheric chemistry and ozone-formation. Recently, unexpected high values of HONO have been detected during the day. Despite its importance, sources of HONO are still poorly understood. Direct emission of HONO or homogeneous chemical formation alone cannot explain the high HONO-to-NO2 ratios often measur...

  9. The formation of the solar system

    OpenAIRE

    Pfalzner, S.; Davies, M. B.; Gounelle, M.; Johansen, A.; Muenker, C.; Lacerda, P.; Zwart, S. Portegies; L. Testi; Trieloff, M.; Veras, D

    2015-01-01

    The solar system started to form about 4.56 Gyr ago and despite the long intervening time span, there still exist several clues about its formation. The three major sources for this information are meteorites, the present solar system structure and the planet-forming systems around young stars. In this introduction we give an overview of the current understanding of the solar system formation from all these different research fields. This includes the question of the lifetime of the solar pro...

  10. A clash of stressors and LTM formation

    OpenAIRE

    de Caigny, Pascaline; Lukowiak, Ken

    2008-01-01

    Stress alters long-term memory formation sometimes enhancing its formation whilst at other times blocking it. It is unclear what the causal mechanisms are that allow stress to either enhance or suppress memory. We have made use of a relatively simple invertebrate model system to attempt to explore the causal mechanisms of how stress alters memory. Here we explore the consequences of presenting to the organism two different ecologically relevant stressors: detection of a predator and crowding....

  11. MAGNETIC EFFECTS IN GLOBAL STAR FORMATION

    Directory of Open Access Journals (Sweden)

    M.-M. Mac Low

    2009-01-01

    Full Text Available I review the effects of magnetic fields on star formation in galaxies. This includes the effects of the magnetorotational instability (MRI at galactic scales, magneto-Jeans and swing instabilities, Parker instabilities, and the effects of magnetic fields on the evolution of supernova-driven turbulence. I argue that currently turbulent support by the MRI appears likely to be the most important of these processes to regulating star formation.

  12. FORMATION OF SINGULARITY FOR COMPRESSIBLE VISCOELASTICITY

    Institute of Scientific and Technical Information of China (English)

    Xianpeng Hu; Dehua Wang

    2012-01-01

    The formation of singularity and breakdown of classical solutions to the threedimensional compressible viscoelasticity and inviscid elasticity are considered. For the compressible inviscid elastic fluids,the finite-time formation of singularity in classical solutions is proved for certain initial data.For the compressible viscoelastic fluids,a criterion in term of the temporal integral of the velocity gradient is obtained for the breakdown of smooth solutions.

  13. Probes of Cosmic Star Formation History

    Indian Academy of Sciences (India)

    Pranab Ghosh

    2002-03-01

    I summarize X-ray diagnostic studies of cosmic star formation history in terms of evolutionary schemes for X-ray binary evolution in normal galaxies with evolving star formation. Deep X-ray imaging studies by Chandra and XMM-Newton are now beginning to constrain both the X-ray luminosity evolution of galaxies and the log – log diagnostics of the X-ray background. I discuss these in the above context, summarizing current understanding and future prospects.

  14. Multidiagnostic Analysis to Track Zeolite Formation

    OpenAIRE

    Castro, M.; Haouas, M.; Taulelle, Francis; Lim, I; Breynaert, Eric; Brabants, Gert; Kirschhock, Christine; Schmidt, W.

    2014-01-01

    Introduction The formation of zeolites in presence of tetraalkylammonium cations from so-called clear solutions using silicon alkoxides is a highly complex process. Our research aims to identify the key mechanisms on a molecular scale with the goal of understanding the factors that drive the formation of zeolites [1]. For this purpose we have used electrospray ionization mass spectrometry (ESI-MS), 29Si and 27Al liquid-NMR spectrometry, DOSY NMR (diffusion experi...

  15. Adolescent Violent Victimization and Precocious Union Formation.

    Science.gov (United States)

    C Kuhl, Danielle; Warner, David F; Wilczak, Andrew

    2012-11-01

    This article bridges scholarship in criminology and family sociology by extending arguments about "precocious exits" from adolescence to consider early union formation as a salient outcome of violent victimization for youths. Research indicates that early union formation is associated with several negative outcomes; yet the absence of attention to union formation as a consequence of violent victimization is noteworthy. We address this gap by drawing on life course theory and data from the National Longitudinal Study of Adolescent Health (Add Health) to examine the effect of violent victimization ("street" violence) on the timing of first co-residential union formation-differentiating between marriage and cohabitation-in young adulthood. Estimates from Cox proportional hazard models show that adolescent victims of street violence experience higher rates of first union formation, especially marriage, early in the transition to adulthood; however, this effect declines with age, as such unions become more normative. Importantly, the effect of violent victimization on first union timing is robust to controls for nonviolent delinquency, substance abuse, and violent perpetration. We conclude by discussing directions for future research on the association between violent victimization and coresidential unions with an eye toward the implications of such early union formation for desistance.

  16. Star formation relations in nearby molecular clouds

    International Nuclear Information System (INIS)

    We test some ideas for star formation relations against data on local molecular clouds. On a cloud by cloud basis, the relation between the surface density of star formation rate and surface density of gas divided by a free-fall time, calculated from the mean cloud density, shows no significant correlation. If a crossing time is substituted for the free-fall time, there is even less correlation. Within a cloud, the star formation rate volume and surface densities increase rapidly with the corresponding gas densities, faster than predicted by models using the free-fall time defined from the local density. A model in which the star formation rate depends linearly on the mass of gas above a visual extinction of 8 mag describes the data on these clouds, with very low dispersion. The data on regions of very massive star formation, with improved star formation rates based on free-free emission from ionized gas, also agree with this linear relation.

  17. Is molecular gas necessary for star formation?

    CERN Document Server

    Glover, S C O

    2011-01-01

    On galactic scales, the surface density of star formation appears to be well correlated with the surface density of molecular gas. This has lead many authors to suggest that there exists a causal relationship between the chemical state of the gas and its ability to form stars -- in other words, the assumption that the gas must be molecular before star formation can occur. We test this hypothesis by modelling star formation within a dense cloud of gas with properties similar to a small molecular cloud using a series of different models of the chemistry, ranging from one in which the formation of molecules is not followed and the gas is assumed to remain atomic throughout, to one that tracks the formation of both H2 and CO. We find that presence of molecules in the gas has little effect on the ability of the gas to form stars: star formation can occur just as easily in atomic gas as in molecular gas. At low densities (< 10^4 cm^-3), the gas is able to cool via C+ fine-structure emission almost as efficiently...

  18. The Void Galaxy Survey: Star Formation Properties

    CERN Document Server

    Beygu, B; van der Hulst, J M; Jarrett, T H; Peletier, R; van de Weygaert, R; van Gorkom, J H; Aragon-Calvo, M A

    2016-01-01

    We study the star formation properties of 59 void galaxies as part of the Void Galaxy Survey (VGS). Current star formation rates are derived from $\\rm{H\\alpha}$ and recent star formation rates from near-UV imaging. In addition, infrared 3.4 $\\rm{\\mu m}$, 4.6 $\\rm{\\mu m}$, 12 $\\rm{\\mu m}$ and 22 $\\rm{\\mu m}$ WISE emission is used as star formation and mass indicator. Infrared and optical colours show that the VGS sample displays a wide range of dust and metallicity properties. We combine these measurements with stellar and HI masses to measure the specific SFRs ($\\rm{SFR/M_{*}}$) and star formation efficiencies ($\\rm{SFR/M_{HI}}$). We compare the star formation properties of our sample with galaxies in the more moderate density regions of the cosmic web, 'the field'. We find that specific SFRs of the VGS galaxies as a function of stellar and HI mass are similar to those of the galaxies in these field regions. Their $\\rm{SFR\\alpha}$ is slightly elevated than the galaxies in the field for a given total HI mass. ...

  19. Dynamic models of lateritic bauxite formation

    Science.gov (United States)

    Zhukov, V. V.; Bogatyrev, B. A.

    2012-09-01

    2D dynamic models of bauxite formation in the weathering mantle covering denudation areas drained by river systems are discussed. The role of relief-forming factors (tectonic uplift, river erosion and denudation of drainage divides), the interrelation of hydrogeological and lithologic structure of the bauxitebearing weathering mantle, and the dynamics of zoning formation above and below groundwater level are described in the models. Creative and destructive epochs of lateritic bauxite formation differing in tectonic regime are distinguished. During the creative epochs, lateritic weathering develops against a background of decreasing denudation and an increase in areas of bauxite formation. The destructive epochs are characterized by intense denudation, cutting down the areas of lateritic bauxite formation and eventually leading to the complete removal of the weathering mantle. Different morphogenetic types and varieties of bauxite-bearing weathering mantles develop during creative and destructive epochs. The morphology of the weathering mantle sections at the deposits of Cenozoic lateritic bauxite in the present-day tropical zone of the Earth corresponds to the destructive epoch, which is characterized by declining areas of lateritic bauxite formation and will end with complete denudation of lateritic bauxite.

  20. Turbulence, Feedback, and Slow Star Formation

    CERN Document Server

    Krumholz, M R

    2006-01-01

    One of the outstanding puzzles about star formation is why it proceeds so slowly. Giant molecular clouds convert only a few percent of their gas into stars per free-fall time, and recent observations show that this low star formation rate is essentially constant over a range of scales from individual cluster-forming molecular clumps in the Milky Way to entire starburst galaxies. This striking result is perhaps the most basic fact that any theory of star formation must explain. I argue that a model in which star formation occurs in virialized structures at a rate regulated by supersonic turbulence can explain this observation. The turbulence in turn is driven by star formation feedback, which injects energy to offset radiation from isothermal shocks and keeps star-forming structures from wandering too far from virial balance. This model is able to reproduce observational results covering a wide range of scales, from the formation times of young clusters to the extragalactic IR-HCN correlation, and makes additi...

  1. Quantitative dynamics of telomere bouquet formation.

    Directory of Open Access Journals (Sweden)

    David M Richards

    Full Text Available The mechanism by which homologous chromosomes pair during meiosis, as a prelude to recombination, has long been mysterious. At meiosis, the telomeres in many organisms attach to the nuclear envelope and move together to form the telomere bouquet, perhaps to facilitate the homologous search. It is believed that diffusion alone is not sufficient to account for the formation of the bouquet, and that some directed movement is also required. Here we consider the formation of the telomere bouquet in a wheat-rye hybrid both experimentally and using mathematical modelling. The large size of the wheat nucleus and wheat's commercial importance make chromosomal pairing in wheat a particularly interesting and important process, which may well shed light on pairing in other organisms. We show that, prior to bouquet formation, sister chromatid telomeres are always attached to a hemisphere of the nuclear membrane and tend to associate in pairs. We study a mutant lacking the Ph1 locus, a locus ensuring correct homologous chromosome pairing, and discover that bouquet formation is delayed in the wild type compared to the mutant. Further, we develop a mathematical model of bouquet formation involving diffusion and directed movement, where we show that directed movement alone is sufficient to explain bouquet formation dynamics.

  2. Adaptable formations utilizing heterogeneous unmanned systems

    Science.gov (United States)

    Barnes, Laura E.; Garcia, Richard; Fields, MaryAnne; Valavanis, Kimon

    2009-05-01

    This paper addresses the problem of controlling and coordinating heterogeneous unmanned systems required to move as a group while maintaining formation. We propose a strategy to coordinate groups of unmanned ground vehicles (UGVs) with one or more unmanned aerial vehicles (UAVs). UAVs can be utilized in one of two ways: (1) as alpha robots to guide the UGVs; and (2) as beta robots to surround the UGVs and adapt accordingly. In the first approach, the UAV guides a swarm of UGVs controlling their overall formation. In the second approach, the UGVs guide the UAVs controlling their formation. The unmanned systems are brought into a formation utilizing artificial potential fields generated from normal and sigmoid functions. These functions control the overall swarm geometry. Nonlinear limiting functions are defined to provide tighter swarm control by modifying and adjusting a set of control variables forcing the swarm to behave according to set constraints. Formations derived are subsets of elliptical curves but can be generalized to any curvilinear shape. Both approaches are demonstrated in simulation and experimentally. To demonstrate the second approach in simulation, a swarm of forty UAVs is utilized in a convoy protection mission. As a convoy of UGVs travels, UAVs dynamically and intelligently adapt their formation in order to protect the convoy of vehicles as it moves. Experimental results are presented to demonstrate the approach using a fully autonomous group of three UGVs and a single UAV helicopter for coordination.

  3. HOW GALACTIC ENVIRONMENT REGULATES STAR FORMATION

    Energy Technology Data Exchange (ETDEWEB)

    Meidt, Sharon E. [Max-Planck-Institut für Astronomie/Königstuhl 17 D-69117 Heidelberg (Germany)

    2016-02-10

    In a new simple model I reconcile two contradictory views on the factors that determine the rate at which molecular clouds form stars—internal structure versus external, environmental influences—providing a unified picture for the regulation of star formation in galaxies. In the presence of external pressure, the pressure gradient set up within a self-gravitating turbulent (isothermal) cloud leads to a non-uniform density distribution. Thus the local environment of a cloud influences its internal structure. In the simple equilibrium model, the fraction of gas at high density in the cloud interior is determined simply by the cloud surface density, which is itself inherited from the pressure in the immediate surroundings. This idea is tested using measurements of the properties of local clouds, which are found to show remarkable agreement with the simple equilibrium model. The model also naturally predicts the star formation relation observed on cloud scales and at the same time provides a mapping between this relation and the closer-to-linear molecular star formation relation measured on larger scales in galaxies. The key is that pressure regulates not only the molecular content of the ISM but also the cloud surface density. I provide a straightforward prescription for the pressure regulation of star formation that can be directly implemented in numerical models. Predictions for the dense gas fraction and star formation efficiency measured on large-scales within galaxies are also presented, establishing the basis for a new picture of star formation regulated by galactic environment.

  4. Converting Taxonomic Descriptions to New Digital Formats

    Directory of Open Access Journals (Sweden)

    Hong Cui

    2008-01-01

    Full Text Available Abstract.--The majority of taxonomic descriptions is currently in print format. The majority of digital descriptions are in formats such as DOC, HTML, or PDF and for human readers. These formats do not convey rich semantics in taxonomic descriptions for computer-aided process. Newer digital formats such as XML and RDF accommodate semantic annotations that allow computers to process the rich semantics on human's behalf, thus open up opportunities for a wide range of innovative usages of taxonomic descriptions, such as searching in more precise and flexible ways, integrating with gnomic and geographic information, generating taxonomic keys automatically, and text data mining and information visualization etc. This paper discusses the challenges in automated conversion of multiple collections of descriptions to XML format and reports an automated system, MARTT. MARTT is a machine-learning system that makes use of training examples to tag new descriptions into XML format. A number of utilities are implemented as solutions to the challenges. The utilities are used to reduce the effort for training example preparation, to facilitate the creation of a comprehensive schema, and to predict system performance on a new collection of descriptions. The system has been tested with several plant and alga taxonomic publications including Flora of China and Flora of North America.

  5. Recognizing team formation in american football

    KAUST Repository

    Atmosukarto, Indriyati

    2014-01-01

    Most existing software packages for sports video analysis require manual annotation of important events in the video. Despite being the most popular sport in the United States, most American football game analysis is still done manually. Line of scrimmage and offensive team formation recognition are two statistics that must be tagged by American Football coaches when watching and evaluating past play video clips, a process which takesmanyman hours per week. These two statistics are the building blocks for more high-level analysis such as play strategy inference and automatic statistic generation. In this chapter, we propose a novel framework where given an American football play clip, we automatically identify the video frame in which the offensive team lines in formation (formation frame), the line of scrimmage for that play, and the type of player formation the offensive team takes on. The proposed framework achieves 95% accuracy in detecting the formation frame, 98% accuracy in detecting the line of scrimmage, and up to 67%accuracy in classifying the offensive team’s formation. To validate our framework, we compiled a large dataset comprising more than 800 play-clips of standard and high definition resolution from real-world football games. This dataset will be made publicly available for future comparison.

  6. SEROMA FORMATION IN CANCER BREAST SURGERY

    Directory of Open Access Journals (Sweden)

    Sitaram

    2015-01-01

    Full Text Available Post - operative breast surgery for malignancy has a common side effect of seromas, whose formation and drainage requires a special attention to prevent as much as possible and as early as possible to avoid morbidity. How best we can prevent the dead space is the problem. In this study a review of various methods adopted all over the world is reviewed includ ing early discharge of the patient with drain. It is always preferable to remove the drain when the collection of serum is less than 25ml in 24 hours the chance of re accumulation of fluid is less likely . INTRODUCTION: Carcinoma breast has remained the sec ond leading cause of cancer death among women worldwide over the past three decades [ 1 ] and contributes significantly to cancer surgical load. Surgical treatment for breast cancer includes breast conservation therapy and mastectomy with or without axillary dissection depending on disease stage. Seroma formation is the most frequent postoperative Side effect seen after mastectomy and axillary surgery with an incidence of 3% to 85% . OBSERVATIONS: TYPE OF SURGERY : Surgical treatment for breast cancer has undergone a paradigm shift from Halstead's radical mastectomy to breast conservation. It has been demonstrated that radical mastectomy increases seroma formation compared with that of simple mastectomy , but the association is inconclusive when radical mastectomy is compared with modified radical mastectomy (MRM . SURGICAL DEVICES : Various electro - mechanical devices are used during surgery to reduce blood loss and operating time. These include electrocautery, laser scalpel, argon diathermy, ultrasonic scalpel, ultrasonic scissors, and vessel sealing systems. All of these devices have been investigated in an effort to reduce seroma formation. Randomized trials have shown that the use of electrocautery for dissecting flaps is significantly associated with increased seroma formation when compared to that of scalpel dissection . However

  7. High mass star formation in the galaxy

    Science.gov (United States)

    Scoville, N. Z.; Good, J. C.

    1987-01-01

    The Galactic distributions of HI, H2, and HII regions are reviewed in order to elucidate the high mass star formation occurring in galactic spiral arms and in active galactic nuclei. Comparison of the large scale distributions of H2 gas and radio HII regions reveals that the rate of formation of OB stars depends on (n sub H2) sup 1.9 where (n sub H2) is the local mean density of H2 averaged over 300 pc scale lengths. In addition the efficiency of high mass star formation is a decreasing function of cloud mass in the range 200,000 to 3,000,000 solar mass. These results suggest that high mass star formation in the galactic disk is initiated by cloud-cloud collisions which are more frequent in the spiral arms due to orbit crowding. Cloud-cloud collisions may also be responsible for high rates of OB star formation in interacting galaxies and galactic nuclei. Based on analysis of the Infrared Astronomy Satellite (IRAS) and CO data for selected GMCs in the Galaxy, the ratio L sub IR/M sub H2 can be as high as 30 solar luminosity/solar mass for GMCs associated with HII regions. The L sub IR/M sub H2 ratios and dust temperature obtained in many of the high luminosity IRAS galaxies are similar to those encountered in galactic GMCs with OB star formation. High mass star formation is therefore a viable explanation for the high infrared luminosity of these galaxies.

  8. Jet formation at the sea ice edge

    Science.gov (United States)

    Feltham, D. L.; Heorton, H. D.

    2014-12-01

    The sea ice edge presents a region of many feedback processes between the atmosphere, ocean and sea ice, which are inadequately represented in current climate models. Here we focus on on-ice atmospheric and oceanic flows at the sea ice edge. Mesoscale jet formation due to the Coriolis effect is well understood over sharp changes in surface roughness such as coastlines. This sharp change in surface roughness is experienced by the atmosphere flowing over, and ocean flowing under, a compacted sea ice edge. We have studied a dynamic sea ice edge responding to atmospheric and oceanic jet formation. The shape and strength of atmospheric and oceanic jets during on-ice flows is calculated from existing studies of the sea ice edge and prescribed to idealised models of the sea ice edge. An idealised analytical model of sea ice drift is developed and compared to a sea ice climate model (the CICE model) run on an idealised domain. The response of the CICE model to jet formation is tested at various resolutions. We find that the formation of atmospheric jets during on-ice winds at the sea ice edge increases the wind speed parallel to the sea ice edge and results in the formation of a sea ice edge jet. The modelled sea ice edge jet is in agreement with an observed jet although more observations are needed for validation. The increase in ice drift speed is dependent upon the angle between the ice edge and wind and can result in a 40% increase in ice transport along the sea ice edge. The possibility of oceanic jet formation during on-ice currents and the resultant effect upon the sea ice edge is less conclusive. Observations and climate model data of the polar oceans has been analysed to show areas of likely atmospheric jet formation, with the Fram Strait being of particular interest.

  9. Numerical simulation of slow spheromak formation: Flux control by formation speed

    Energy Technology Data Exchange (ETDEWEB)

    Sato, T.; Todd, A.M.M.; Okuda, H.

    1983-03-01

    Two-dimensional magnetohydrodynamic simulations of the Princeton S-1 Spheromak have been carried out for several formation speeds. It is found that the spheromak size and shape, and hence the confined poloidal and toroidal fluxes, are largely dependent upon the formation speed, provided this is moderately slow. Specifically, the total toroidal and poloidal fluxes in a spheromak increase as the formation speed is reduced. The role of externally driven reconnection as a cause for this dependence is discussed.

  10. Free-format RPG IV the express guide to learning free format

    CERN Document Server

    Martin, Jim

    2015-01-01

    Focusing strictly on teaching free-format RPG programming methods, this book will help programmers wishing to upgrade their skills   This how-to guide offers a concise and thorough introduction to the increased productivity, better readability, and easier program maintenance that comes with the free-format style of programming in RPG IV. Although free-format information is available in IBM manuals, it is not separated from everything else, requiring hours of tedious research to track down the information needed. This book provides everything you need to know to write RPG IV in the free-format

  11. Halonitromethanes formation in wastewater treatment plant effluents.

    Science.gov (United States)

    Song, Hocheol; Addison, Jesse W; Hu, Jia; Karanfil, Tanju

    2010-03-01

    Halonitromethanes (HNMs) constitute one class of emerging disinfection by-products with high potential health risks. This study investigated the formation and occurrence of HNMs under different disinfection scenarios and the presence of their precursors in municipal wastewater treatment plant (WWTPs) effluents. Formation potential tests performed on WWTP effluents revealed that HNM formation occurred in the order of ozonation-chlorination > ozonation-chloramination > chlorination > chloramination. Ozonation alone did not produce any HNM. Municipal WWTP effluents contained some reactive HNM precursors, possibly the by-products of biological treatment processes and/or some moiety of industry or household origin. No effects of nitrate on the formation of HNMs were observed in this study, and nitrification in WWTPs appears to remove appreciable portion of HNM precursors, especially those reactive to chlorine. UV disinfection using low pressure lamps in municipal WWTPs had negligible impact on HNM formation potential. HNM concentrations in the effluents of selected WWTPs were either non-detectable or less than minimum reporting level, except for one WWTP that gave trichloronitromethane concentrations in the range of 0.9-1.5 microg L(-1). No HNMs were observed in the effluents disinfected with UV radiation. Therefore, it appears the typical wastewater disinfection processes involving chlorination or UV treatment in WWTPs do not produce significant amounts of HNMs.

  12. Prompt Planetesimal Formation beyond the Snow Line

    Science.gov (United States)

    Armitage, Philip J.; Eisner, Josh A.; Simon, Jacob B.

    2016-09-01

    We develop a simple model to predict the radial distribution of planetesimal formation. The model is based on the observed growth of dust to millimeter-sized particles, which drift radially, pile-up, and form planetesimals where the stopping time and dust-to-gas ratio intersect the allowed region for streaming instability-induced gravitational collapse. Using an approximate analytic treatment, we first show that drifting particles define a track in metallicity–stopping time space whose only substantial dependence is on the disk’s angular momentum transport efficiency. Prompt planetesimal formation is feasible for high particle accretion rates (relative to the gas, {\\dot{M}}p/\\dot{M}≳ 3× {10}-2 for α ={10}-2), which could only be sustained for a limited period of time. If it is possible, it would lead to the deposition of a broad and massive belt of planetesimals with a sharp outer edge. Numerically including turbulent diffusion and vapor condensation processes, we find that a modest enhancement of solids near the snow line occurs for centimeter-sized particles, but that this is largely immaterial for planetesimal formation. We note that radial drift couples planetesimal formation across radii in the disk, and suggest that considerations of planetesimal formation favor a model in which the initial deposition of material for giant planet cores occurs well beyond the snow line.

  13. Star Formation Relations in the Milky Way

    CERN Document Server

    Vutisalchavakul, Nalin; Heyer, Mark

    2016-01-01

    The relations between star formation and properties of molecular clouds are studied based on a sample of star forming regions in the Galactic Plane. Sources were selected by having radio recombination lines to provide identification of associated molecular clouds and dense clumps. Radio continuum and mid-infrared emission were used to determine star formation rates, while 13CO and submillimeter dust continuum emission were used to obtain masses of molecular and dense gas, respectively. We test whether total molecular gas or dense gas provides the best predictor of star formation rate. We also test two specific theoretical models, one relying on the molecular mass divided by the free-fall time, the other using the free-fall time divided by the crossing time. Neither is supported by the data. The data are also compared to those from nearby star forming regions and extragalactic data. The star formation "efficiency," defined as star formation rate divided by mass, spreads over a large range when the mass refers ...

  14. Prompt Planetesimal Formation beyond the Snow Line

    Science.gov (United States)

    Armitage, Philip J.; Eisner, Josh A.; Simon, Jacob B.

    2016-09-01

    We develop a simple model to predict the radial distribution of planetesimal formation. The model is based on the observed growth of dust to millimeter-sized particles, which drift radially, pile-up, and form planetesimals where the stopping time and dust-to-gas ratio intersect the allowed region for streaming instability-induced gravitational collapse. Using an approximate analytic treatment, we first show that drifting particles define a track in metallicity-stopping time space whose only substantial dependence is on the disk’s angular momentum transport efficiency. Prompt planetesimal formation is feasible for high particle accretion rates (relative to the gas, {\\dot{M}}p/\\dot{M}≳ 3× {10}-2 for α ={10}-2), which could only be sustained for a limited period of time. If it is possible, it would lead to the deposition of a broad and massive belt of planetesimals with a sharp outer edge. Numerically including turbulent diffusion and vapor condensation processes, we find that a modest enhancement of solids near the snow line occurs for centimeter-sized particles, but that this is largely immaterial for planetesimal formation. We note that radial drift couples planetesimal formation across radii in the disk, and suggest that considerations of planetesimal formation favor a model in which the initial deposition of material for giant planet cores occurs well beyond the snow line.

  15. Molecular mechanisms of bone formation in spondyloarthritis.

    Science.gov (United States)

    González-Chávez, Susana Aideé; Quiñonez-Flores, Celia María; Pacheco-Tena, César

    2016-07-01

    Spondyloarthritis comprise a group of inflammatory rheumatic diseases characterized by its association to HLA-B27 and the presence of arthritis and enthesitis. The pathogenesis involves both an inflammatory process and new bone formation, which eventually lead to ankylosis of the spine. To date, the intrinsic mechanisms of the pathogenic process have not been fully elucidated, and our progress is remarkable in the identification of therapeutic targets to achieve the control of the inflammatory process, yet our ability to inhibit the excessive bone formation is still insufficient. The study of new bone formation in spondyloarthritis has been mostly conducted in animal models of the disease and only few experiments have been done using human biopsies. The deregulation and overexpression of molecules involved in the osteogenesis process have been observed in bone cells, mesenchymal cells, and fibroblasts. The signaling associated to the excessive bone formation is congruent with those involved in the physiological processes of bone remodeling. Bone morphogenetic proteins and Wnt pathways have been found deregulated in this disease; however, the cause for uncontrolled stimulation remains unknown. Mechanical stress appears to play an important role in the pathological osteogenesis process; nevertheless, the association of other important factors, such as the presence of HLA-B27 and environmental factors, remains uncertain. The present review summarizes the experimental findings that describe the signaling pathways involved in the new bone formation process in spondyloarthritis in animal models and in human biopsies. The role of mechanical stress as the trigger of these pathways is also reviewed. PMID:26838262

  16. Laser filament-induced aerosol formation

    Directory of Open Access Journals (Sweden)

    H. Saathoff

    2012-11-01

    Full Text Available Using the aerosol and cloud simulation chamber AIDA we investigated the laser filament induced particle formation in ambient air, humid synthetic air, humid nitrogen, argon-oxygen mixture, and pure argon in order to simulate the particle formation under realistic atmospheric conditions as well as to investigate the influence of typical gas-phase atmospheric constituents on the particle formation. Terawatt laser plasma filaments generated new particles in the size range 3 to 130 nm with particle production rates ranging from 1 × 107 to 5 × 109 cm−3 plasma s−1. In all cases the particle formation rates increased exponentially with the water content of the gas mixture. Furthermore, the presence of a few ppb of trace gases like SO2 and α-pinene clearly enhanced the particle yield by number, the latter also by mass. Our findings suggest that new particle formation is efficiently supported by acids generated by the photo-ionization of both major and minor components of the air, including N2, NH3, SO2 and organics.

  17. Cloud Optimized Image Format and Compression

    Science.gov (United States)

    Becker, P.; Plesea, L.; Maurer, T.

    2015-04-01

    Cloud based image storage and processing requires revaluation of formats and processing methods. For the true value of the massive volumes of earth observation data to be realized, the image data needs to be accessible from the cloud. Traditional file formats such as TIF and NITF were developed in the hay day of the desktop and assumed fast low latency file access. Other formats such as JPEG2000 provide for streaming protocols for pixel data, but still require a server to have file access. These concepts no longer truly hold in cloud based elastic storage and computation environments. This paper will provide details of a newly evolving image storage format (MRF) and compression that is optimized for cloud environments. Although the cost of storage continues to fall for large data volumes, there is still significant value in compression. For imagery data to be used in analysis and exploit the extended dynamic range of the new sensors, lossless or controlled lossy compression is of high value. Compression decreases the data volumes stored and reduces the data transferred, but the reduced data size must be balanced with the CPU required to decompress. The paper also outlines a new compression algorithm (LERC) for imagery and elevation data that optimizes this balance. Advantages of the compression include its simple to implement algorithm that enables it to be efficiently accessed using JavaScript. Combing this new cloud based image storage format and compression will help resolve some of the challenges of big image data on the internet.

  18. Controls of tor formation, Cairngorm Mountains, Scotland

    Science.gov (United States)

    Goodfellow, Bradley W.; Skelton, Alasdair; Martel, Stephen J.; Stroeven, Arjen P.; Jansson, Krister N.; Hättestrand, Clas

    2014-02-01

    Tors occur in many granitic landscapes and provide opportunities to better understand differential weathering. We assess tor formation in the Cairngorm Mountains, Scotland, by examining correlation of tor location and size with grain size and the spacing of steeply dipping joints. We infer a control on these relationships and explore its potential broader significance for differential weathering and tor formation. We also assess the relationship between the formation of subhorizontal joints in many tors and local topographic shape by evaluating principle surface curvatures from a digital elevation model of the Cairngorms. We then explore the implications of these joints for tor formation. We conclude that the Cairngorm tors have formed in kernels of relatively coarse grained granite. Tor volumes increase with grain size and the spacing of steeply dipping joints. We infer that the steeply dipping joints largely formed during pluton cooling and are more widely spaced in tor kernels because of slower cooling rates. Preferential tor formation in coarser granite with a wider joint spacing that is more easily grusified indicates that joint spacing is a dominant control on differential weathering. Sheet jointing is well developed in tors located on relatively high convex surfaces. This jointing formed after the gross topography of the Cairngorms was established and before tor emergence. The presence of closely spaced (tens of centimeters), subhorizontal sheeting joints in tors indicates that these tors, and similarly sheeted tors elsewhere, formed either after subaerial exposure of bedrock or have progressively emerged from a regolith only a few meters thick.

  19. Crenarchaeal biofilm formation under extreme conditions.

    Directory of Open Access Journals (Sweden)

    Andrea Koerdt

    Full Text Available BACKGROUND: Biofilm formation has been studied in much detail for a variety of bacterial species, as it plays a major role in the pathogenicity of bacteria. However, only limited information is available for the development of archaeal communities that are frequently found in many natural environments. METHODOLOGY: We have analyzed biofilm formation in three closely related hyperthermophilic crenarchaeotes: Sulfolobus acidocaldarius, S. solfataricus and S. tokodaii. We established a microtitre plate assay adapted to high temperatures to determine how pH and temperature influence biofilm formation in these organisms. Biofilm analysis by confocal laser scanning microscopy demonstrated that the three strains form very different communities ranging from simple carpet-like structures in S. solfataricus to high density tower-like structures in S. acidocaldarius in static systems. Lectin staining indicated that all three strains produced extracellular polysaccharides containing glucose, galactose, mannose and N-acetylglucosamine once biofilm formation was initiated. While flagella mutants had no phenotype in two days old static biofilms of S. solfataricus, a UV-induced pili deletion mutant showed decreased attachment of cells. CONCLUSION: The study gives first insights into formation and development of crenarchaeal biofilms in extreme environments.

  20. Performance of Different Acids on Sandstone Formations

    Directory of Open Access Journals (Sweden)

    M. A. Zaman

    2013-12-01

    Full Text Available Stimulation of sandstone formations is a challenging task, which involves several chemicals and physical interactions of the acid with the formation. Some of these reactions may result in formation damage. Mud acid has been successfully used to stimulate sandstone reservoirs for a number of years. It is a mixture of hydrofluoric (HF and hydrochloric (HCl acids designed to dissolve clays and siliceous fines accumulated in the near-wellbore region. Matrix acidizing may also be used to increase formation permeability in undamaged wells. The change may be up to 50% to 100% with the mud acid. For any acidizing process, the selection of acid (Formulation and Concentration and the design (Pre-flush, Main Acid, After-flush is very important. Different researchers are using different combinations of acids with different concentrations to get the best results for acidization. Mainly the common practice is combination of Hydrochloric Acid – Hydrofluoric with Concentration (3% HF – 12% HCl. This paper presents the results of a laboratory investigation of Orthophosphoric acid instead of hydrochloric acid in one combination and the second combination is Fluoboric and formic acid and the third one is formic and hydrofluoric acid. The results are compared with the mud acid and the results calculated are porosity, permeability, and FESEM Analysis and Strength tests. All of these new combinations shows that these have the potential to be used as acidizing acids on sandstone formations.