Penetrative trace fossils from the late Ediacaran of Mongolia: early onset of the agronomic revolution

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Oji, Tatsuo; Dornbos, Stephen Q.; Yada, Keigo; Hasegawa, Hitoshi; Gonchigdorj, Sersmaa; Mochizuki, Takafumi; Takayanagi, Hideko; Iryu, Yasufumi

2018-02-01

The Cambrian radiation of complex animals includes a dramatic increase in the depth and intensity of bioturbation in seafloor sediment known as the `agronomic revolution'. This bioturbation transition was coupled with a shift in dominant trace fossil style from horizontal surficial traces in the late Precambrian to vertically penetrative trace fossils in the Cambrian. Here we show the existence of the first vertically penetrative trace fossils from the latest Ediacaran: dense occurrences of the U-shaped trace fossil Arenicolites from late Precambrian marine carbonates of Western Mongolia. Their Ediacaran age is established through stable carbon isotope chemostratigraphy and their occurrence stratigraphically below the first appearance of the trace fossil Treptichnus pedum. These Arenicolites are large in diameter, penetrate down to at least 4 cm into the sediment, and were presumably formed by the activity of bilaterian animals. They are preserved commonly as paired circular openings on bedding planes with maximum diameters ranging up to almost 1 cm, and as U- and J-shaped tubes in vertical sections of beds. Discovery of these complex penetrative trace fossils demonstrates that the agronomic revolution started earlier than previously considered.

Paleomagnetic evidence of a Late ediacaran ocean in South America?

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Rapalini, A.; Sanchez Bettucci, L.; Tohver, E.

2016-01-01

In recent years, a controversy arose on whether a large ocean, called Cymene, existed between the Amazon ian craton and the Rio de la Plata / Congo-Sao Francisco craton s in the late Ediacaran. Comparison of the available reliable Paleomagnetic poles from the latter two craton s, West Africa and Lauren tia for the interval 615-560 Ma suggests that by ca. 575 Ma a large ocean existed between Lauren tia-Amazon ia-West Africa on one side and Río de la Plata and Congo-Sao Francisco on the other. This conclusion is still valid whether the “high latitude” or the “low latitude” option is chosen for Lauren tia. However, Paleomagnetic data from the proper Amazon ia are needed for definite conclusions

Decoupling of body-plan diversification and ecological structuring during the Ediacaran-Cambrian transition: evolutionary and geobiological feedbacks.

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Mángano, M Gabriela; Buatois, Luis A

2014-04-07

The rapid appearance of bilaterian clades at the beginning of the Phanerozoic is one of the most intriguing topics in macroevolution. However, the complex feedbacks between diversification and ecological interactions are still poorly understood. Here, we show that a systematic and comprehensive analysis of the trace-fossil record of the Ediacaran-Cambrian transition indicates that body-plan diversification and ecological structuring were decoupled. The appearance of a wide repertoire of behavioural strategies and body plans occurred by the Fortunian. However, a major shift in benthic ecological structure, recording the establishment of a suspension-feeder infauna, increased complexity of the trophic web, and coupling of benthos and plankton took place during Cambrian Stage 2. Both phases were accompanied by different styles of ecosystem engineering, but only the second one resulted in the establishment of the Phanerozoic-style ecology. In turn, the suspension-feeding infauna may have been the ecological drivers of a further diversification of deposit-feeding strategies by Cambrian Stage 3, favouring an ecological spillover scenario. Trace-fossil information strongly supports the Cambrian explosion, but allows for a short time of phylogenetic fuse during the terminal Ediacaran-Fortunian.

The Strontium Isotope Record of Zavkhan Terrane Carbonates: Strontium Isotope Stability Through the Ediacaran-Cambrian Transition

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Petach, Tanya N.

2015-01-01

First order trends in the strontium isotopic (87Sr/86Sr) composition of seawater are controlled by radiogenic inputs from the continent and non-radiogenic inputs from exchange at mid-ocean ridges. Carbonates precipitated in seawater preserve trace amounts of strontium that record this isotope ratio and therefore record the relative importance of mid-ocean ridge and weathering chemical inputs to sea water composition. It has been proposed that environmental changes during the Ediacaran-Cambria...

A geochemical study of the Ediacaran discoidal fossil Aspidella preserved in limestones: Implications for its taphonomy and paleoecology.

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Bykova, N; Gill, B C; Grazhdankin, D; Rogov, V; Xiao, S

2017-07-01

The Ediacara biota features the rise of macroscopic complex life immediately before the Cambrian explosion. One of the most abundant and widely distributed elements of the Ediacara biota is the discoidal fossil Aspidella, which is interpreted as a subsurface holdfast possibly anchoring a frondose epibenthic organism. It is a morphologically simple fossil preserved mainly in siliciclastic rocks, which are unsuitable for comprehensive stable isotope geochemical analyses to decipher its taphonomy and paleoecology. In this regard, three-dimensionally preserved Aspidella fossils from upper Ediacaran limestones of the Khatyspyt Formation in the Olenek Uplift of northern Siberia offer a rare opportunity to leverage geochemistry for insights into their taphonomy and paleoecology. To take advantage of this opportunity, we analyzed δ 13 C carb , δ 18 O carb , δ 13 C org , δ 34 S pyr , and iron speciation of the Khatyspyt Aspidella fossils and surrounding sediment matrix in order to investigate whether they hosted microbial symbionts, how they were fossilized, and the redox conditions of their ecological environments. Aspidella holdfasts and surrounding sediment matrix show indistinguishable δ 13 C org values, suggesting they did not host and derive significant amount of nutrients from microbial symbionts such as methanogens, methylotrophs, or sulfide-oxidizing bacteria. δ 13 C carb , δ 18 O carb , and δ 34 S pyr data, along with petrographic observations, suggest that microbial sulfate reduction facilitated the preservation of Aspidella by promoting early authigenic calcite cementation in the holdfasts before matrix cementation and sediment compaction. Iron speciation data are equivocal, largely because of the low total iron concentrations. However, consideration of published sulfur isotope and biomarker data suggests that Aspidella likely lived in non-euxinic waters. It is possible that Aspidella was an opportunistic organism, colonizing the seafloor in large

A preserved early Ediacaran magmatic arc at the northernmost portion of the Transversal Zone central subprovince of the Borborema Province, Northeastern South America

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Benjamim Bley de Brito Neves

Full Text Available ABSTRACT: Magmatic arcs are an essential part of crust-forming events in planet Earth evolution. The aim of this work was to describe an early Ediacaran magmatic arc (ca. 635-580 Ma exposed in the northernmost portion of the Transversal Zone, central subprovince of Borborema Province, northeast Brazil. Our research took advantage of several syntheses by different authors, including theses and dissertations, carried out on magmatic rocks of the study area for the last 30 years. The ca. 750 km long and up to 140 km wide arc, trending ENE-WSW, is preserved to the south of the Patos Lineament, between 35º15' and 42º30'W and 7º15' and 8ºS. About 90 different stocks and batholiths of I-type granitic rocks were mapped along this orogenic zone, preferentially intruding low-grade schists of the Cryogenian-Ediacaran Piancó-Alto Brígida (SPAB belt. Three igneous supersuites are recognized: a epidote-bearing granodiorites and tonalites ("Conceição" type; b high-K calc-alkaline granites ("Itaporanga" type; c biotite granodiorites of trondhjemite affinity ("Serrita" type. A fourth group of peralkalic and shoshonitic rocks occurs to the south of the previous ones, reflecting special tectonic conditions. NNE-SSW trending Paleoproterozoic fold belts, surrounding Archean nuclei, characterize the continental part of the northern lower plate. The oceanic fraction of this lower plate was recycled by subduction and scarce remnants of which may be seen either within the enclosing low-grade schists or as xenoliths within the arc intrusions. The upper continental plate presents WSW-ENE structural trends and is composed of Neoproterozoic fold belts and Paleoproterozoic reworked basement inliers. Available data bear clear evidence of an Ediacaran magmatic arc built at the northern portion of the Transversal Zone in the Borborema Province, northeast Brazil.

The nature and origin of nucleus-like intracellular inclusions in Paleoproterozoic eukaryote microfossils.

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Pang, K; Tang, Q; Schiffbauer, J D; Yao, J; Yuan, X; Wan, B; Chen, L; Ou, Z; Xiao, S

2013-11-01

The well-known debate on the nature and origin of intracellular inclusions (ICIs) in silicified microfossils from the early Neoproterozoic Bitter Springs Formation has recently been revived by reports of possible fossilized nuclei in phosphatized animal embryo-like fossils from the Ediacaran Doushantuo Formation of South China. The revisitation of this discussion prompted a critical and comprehensive investigation of ICIs in some of the oldest indisputable eukaryote microfossils-the ornamented acritarchs Dictyosphaera delicata and Shuiyousphaeridium macroreticulatum from the Paleoproterozoic Ruyang Group of North China-using a suite of characterization approaches: scanning electron microscopy (SEM), transmission electron microscopy (TEM), and focused ion beam scanning electron microscopy (FIB-SEM). Although the Ruyang acritarchs must have had nuclei when alive, our data suggest that their ICIs represent neither fossilized nuclei nor taphonomically condensed cytoplasm. We instead propose that these ICIs likely represent biologically contracted and consolidated eukaryotic protoplasts (the combination of the nucleus, surrounding cytoplasm, and plasma membrane). As opposed to degradational contraction of prokaryotic cells within a mucoidal sheath-a model proposed to explain the Bitter Springs ICIs-our model implies that protoplast condensation in the Ruyang acritarchs was an in vivo biologically programmed response to adverse conditions in preparation for encystment. While the discovery of bona fide nuclei in Paleoproterozoic acritarchs would be a substantial landmark in our understanding of eukaryote evolution, the various processes (such as degradational and biological condensation of protoplasts) capable of producing nuclei-mimicking structures require that interpretation of ICIs as fossilized nuclei be based on comprehensive investigations. © 2013 John Wiley & Sons Ltd.

Petrogenesis of the NE Gondwanan uppermost Ediacaran-Lower Cretaceous siliciclastic sequence of Jordan: Provenance, tectonic, and climatic implications

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Amireh, Belal S.

2018-04-01

Detrital framework modes of the NE Gondwanan uppermost Ediacaran-Lower Cretaceous siliciclastic sequence of Jordan are determined employing the routine polarized light microscope. The lower part of this sequence constitutes a segment of the vast lower Paleozoic siliciclastic sheet flanking the northern Gondwana margin that was deposited over a regional unconformity truncating the outskirts of the East African orogen in the aftermath of the Neoproterozoic amalgamation of Gondwana. The research aims to evaluate the factors governing the detrital light mineral composition of this sandstone. The provenance terranes of the Arabian craton controlled by plate tectonics appear to be the primary factor in most of the formations, which could be either directly inferred employing Dickinson's compositional triangles or implied utilizing the petrographic data achieved and the available tectonic and geological data. The Arabian-Nubian Shield constitutes invariably the craton interior or the transitional provenance terrane within the NE Gondwana continental block that consistently supplied sandy detritus through northward-flowing braided rivers to all the lower Paleozoic formations. On the other hand, the Lower Cretaceous Series received siliciclastic debris, through braided-meandering rivers having same northward dispersal direction, additionally from the lower Paleozoic and lower-middle Mesozoic platform strata in the Arabian Craton. The formations making about 50% of the siliciclastic sequence represent a success for Dickinson's plate tectonics-provenance approach in attributing the detrital framework components primarily to the plate tectonic setting of the provenance terranes. However, even under this success, the varying effects of the other secondary sedimentological and paleoclimatological factors are important and could be crucial. The inapplicability of this approach to infer the appropriate provenance terranes of the remaining formations could be ascribed either to the

Late Ediacaran-Cambrian structures and their reactivation during the Variscan and Alpine cycles in the Anti-Atlas (Morocco)

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Soulaimani, A.; Michard, A.; Ouanaimi, H.; Baidder, L.; Raddi, Y.; Saddiqi, O.; Rjimati, E. C.

2014-10-01

The post-Pan-African evolution of the northern border of the West African Craton is largely controlled by the remobilisation of Late Neoproterozoic basement faults. The Upper Ediacaran volcanic and volcano-sedimentary sequences of the Ouarzazate Group show dramatic and rapid thickness changes, consistent with active extensional faulting associated with post-orogenic collapse and incipient continental rifting. The geometry and kinematics of these faults differ from west to east in the Anti-Atlas. N- to NE-trending faults dominate in western Anti-Atlas in response to E-W to NW-SE pure extension, while a transtensive opening regime characterize the central (Bou Azzer) and eastern (Saghro-Ougnate) Anti-Atlas. The marine incursion in the west-central Anti-Atlas during the late Ediacaran-Early Cambrian occurred without major geodynamical break between the continental Ouarzazate Group and marine sediments of the Adoudou Fm. Extensional tectonics went on during the Early Cambrian, being concentrated in the western and central parts of the belt. From Middle Cambrian to Lower Devonian and mainly due to thermal subsidence, the Anti-Atlas basement was buried under marine sediments with dominant south-derived detrital input. Basement faults control the distribution of subsiding versus shallow areas. During the Middle-Late Devonian, the dislocation of the Saharan platform occurred, mainly in the eastern Anti-Atlas where Precambrian faults were also remobilized during the Early Carboniferous. During the Variscan orogeny, the Paleozoic series of the Anti-Atlas basin were involved in folding tectonics, concomitant with the uplift of Proterozoic basement blocks bounded by inherited basement faults. The pre-existing rift-related faults were variably inverted across the Anti-Atlas. In the westernmost part of the belt, Variscan shortening induced positive inversions along the remobilized basement faults, but in some cases, some faults preserved an apparently normal throw. Some hidden

Ediacaran ( 620 Ma) high grade regional metamorphism in the northern Arabian Nubian Shield: U/Th-Pb monazite ages of the Elat schist

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Elisha, Bar; Katzir, Yaron; Kylander-Clark, Andrew

2017-04-01

Ediacaran times witnessed a hemisphere-scale orogenesis forming the extensive Pan-African mountain ranges and resulting in the final assembly of Gondwana supercontinent. The Elat metamorphic basement (S Israel) located at the northernmost tip of a major Pan-African orogenic suture, the Arabian Nubian Shield (ANS), comprises amphibolite facies schists and gneisses and was most likely shaped by this major continental collision. However the timing, number and duration of metamorphic events in Elat and elsewhere in the ANS are non-conclusive and a major emphasis was given to pre-Ediacaran island-arc related tectonics. This is mostly because U-Pb dating of zircon, widely used in Elat and elsewhere, is very successful in constraining the ages of the igneous and sedimentary protoliths, but is 'blind' to metamorphism at grades lower than granulite. Here U/Th-Pb dating of monazite, a precise chronometer of metamorphic mineral growth, is systematically applied to the Elat schist and unveils the tectono-metamorphic evolution of the Elat basement. Previous U-Pb dating of detrital zircon has shown that the sedimentary protoliths of the Elat schist are the oldest basement components (≥800 Ma), and detailed structural observations of the schists portrayed a complex deformation history including four successive phases (Shimron, 1972). The earliest three phases were defined as ductile and penetrative, but some of the available geochronological data apparently contradict field relations. In-situ analysis of metamorphic monazites by LASS (Laser Ablation Split Stream) involves simultaneous measurement of U/Th-Pb isotope ratios and REE contents in a single 10 μm sized grain or domain, thus allowing determining the age of specific texture and metamorphic assemblage. Monazite dating of the Elat schist yielded two concordant age clusters at 712±6 and 613±5 Ma. The corresponding REE patterns of the dated monazite grains indicate that porphyroblast growth, either garnet or staurolite

Evidence for Biogenic Iron in Ediacaran Limestones of the Yenisei Ridge Vorogovka Series (South-Western Framing of the Siberian Craton).

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Vinogradov, E.; Kosareva, L.; Metelkin, D. V.; Vishnevskaya, I.

2017-12-01

The composition and origin of magnetic minerals are used for reconstructing paleogeography and changes in paleoenvironments. Ediacaran limestones of the Vorogovka Series were studied in the Yenisei Ridge. Rock magnetism of the upper part of the Vorogovka Series completely depends on terrigenous admixture of iron. Non-carbonate residue consists of quartz, plagioclase, muscovite, Fe-Mg chlorite, smectite and pyrite. A prominent positive correlation is observed between the Fe content (1550…9350 ppm) and the amount of insoluble residue. Magnetization of the lower part of Vorogovka Series is due to authigenic iron. There are several indirect indications of the presence of magnetotactic bacteria and seaweed remains in these limestones. While Fe content is high (1200…8330 ppm), Fe-hydroxides, pyrite and other minerals indicating secondary transformations were not detected. Thus, iron was included in the carbonate material during sedimentation. There is no correlation between iron content and the amount of insoluble residue, which indicates that iron could not have been taken from terrigenous admixture. Study of the dependence of magnetic susceptibility from temperature in inert atmosphere (argon) revealed magnetic minerals with demagnetization temperatures of 320°C and 580°C. The former may correspond to greigite (Curie Temperature 307°C) or hexagonal pyrrhotine (325°C). The latter indicates magnetite (Curie Temperature 586°C) which may be authigenic or newly formed during the experiment. Both magnetite and greigite, are major biogenic minerals produced by magnetotactic bacteria. The main environment of modern magnetotactic bacteria is microaerophilic habitat. Therefore, their abundant presence in the Ediacaran sediments is quite natural. All of these are preliminary conclusions until bacteria can be visualized by electron microscopy, which is an ongoing. The work was supported by the Ministry of Education and Science of Russia 5.2324.2017/4.6 and the RFBR 15-05-01428.

Evidence of early Archean crust in northwest Gondwana, from U-Pb and Hf isotope analysis of detrital zircon, in Ediacaran surpacrustal rocks of northern Spain

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Naidoo, Thanusha; Zimmermann, Udo; Vervoort, Jeff; Tait, Jenny

2018-03-01

The Mora Formation (Narcea Group) is one of the oldest Precambrian supracrustal successions in northern Spain. Here, we use U-Pb and in situ Hf isotope analysis on detrital zircon to determine its age and provenance. The youngest U-Pb dates constrain the maximum depositional age of the Mora Formation at 565 ± 11 Ma. Results indicate: (1) a dominant Ediacaran zircon population (33%; 565-633 Ma, Cadomian) within a spectrum of Neoproterozoic ages (40%; 636-996 Ma); and (2) smaller Mesoproterozoic (5%; 1004-1240 Ma), Palaeoproterozoic (11%; 1890-2476 Ma) and Archean (11%; 2519-3550 Ma) populations. Results here do not point to one specific cratonic source area; instead, detritus may have been derived from the West African craton and Amazonia, or even the concealed Iberian basement. The lack of 1.3-1.8 Ga grains suggests exclusion of the Sahara Craton as a major source, but this is not certain. This mixed composition favours a complex source history with reworking of detritus across terrane/craton boundaries. Hafnium isotope compositions indicate a range of crustal and juvenile sources, with initial ɛHf values between -15.8 and 11.1, and Hf model ages from 0.8 to 3.7 Ga. For Neoproterozoic zircons (80%), juvenile components (ɛHf(i) +10) may be related to Rodinia fragmentation and the onset of an active margin setting leading to the Cadomian orogeny. Palaeoproterozoic to Paleoarchean grains (20%) all have negative ɛHf values and Meso- to Eoarchean Hf model ages. This indicates an early (Archean) sialic crustal component for northwestern Gondwana.

Strongly seasonal Proterozoic glacial climate in low palaeolatitudes: Radically different climate system on the pre-Ediacaran Earth

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George E. Williams

2016-07-01

Full Text Available Proterozoic (pre-Ediacaran glaciations occurred under strongly seasonal climates near sea level in low palaeolatitudes. Metre-scale primary sand wedges in Cryogenian periglacial deposits are identical to those actively forming, through the infilling of seasonal (winter thermal contraction-cracks in permafrost by windblown sand, in present-day polar regions with a mean monthly air temperature range of 40 °C and mean annual air temperatures of −20 °C or lower. Varve-like rhythmites with dropstones in Proterozoic glacial successions are consistent with an active seasonal freeze–thaw cycle. The seasonal (annual oscillation of sea level recorded by tidal rhythmites in Cryogenian glacial successions indicates a significant seasonal cycle and extensive open seas. Palaeomagnetic data determined directly for Proterozoic glacial deposits and closely associated rocks indicate low palaeolatitudes: Cryogenian deposits in South Australia accumulated at ≤10°, most other Cryogenian deposits at 54° during Proterozoic low-latitude glaciations, whereby the equator would be cooler than the poles, on average, and global seasonality would be greatly amplified.

Pan African Collisional Tectonics Along the Moroccan West African Craton Continued to Ediacaran-Cambrian Boundary

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Hefferan, K. P.; Samson, S. D.; Rice, K.; Soulaimani, A.

2016-12-01

Precision geochronologic dating and field mapping in the Anti-Atlas Mountains of Morocco document a Neoproterozoic Pan African orogenic cycle consisting of three distinct orogenic events: Iriri-Tichibanine orogeny (760-700 Ma), Bou Azzer orogeny (680-640 Ma) and the WACadomian orogeny (620 Ma to either 555 or 544 Ma). The Iriri-Tichibanine and Bou Azzer orogenies involved northward directed subduction beneath island arc volcanic terranes. These orogenic events generated calc-alkaline magmatism and supra-subduction zone ophiolites exposed in the Bou Azzer and Siroua erosional inliers. The WACadomian orogeny involved subduction and collision of the Cadomia arc complex with the West African Craton and generation of clastic sedimentary basins. The termination of the WACadomian orogeny has been the subject of debate as calc-alkaline to high K magmatism and folding continued to 544 Ma: Was 620-544 Ma calc-alkaline to high K magmatism and clastic basin development due to a) continental rift basin tectonics or b) southward directed subduction and collisional tectonics with associated back arc basin tectonism? We present field and geochemical data supporting the continuation of subduction-collisional tectonics to the Ediacaran-Cambrian boundary 544 Ma. Field mapping in the Central Anti-Atlas (Agadir Melloul) clearly documents an angular unconformity between Ouarzazate Group and Adoudounian limestones (N 30°31'28.91", W07°48'29.12"). Volcaniclastic rocks of Ouarzazate Group (615-545 Ma) are clearly folded and unconformably overlain by Adoudou Formation (541-529 Ma) limestones to the north. Geochemical discrimination diagrams on Latest Neoproterozoic calc-alkaline to high K igneous rocks throughout the Anti-Atlas plot in subduction and collisional arc magma domains. Back arc basin tectonism is likely responsible for localized extensional basins but continental rift tectonics and passive margin sedimentation did not begin in the Anti-Atlas Mountains until Early

U-Pb geochronology and paleomagnetism of the Neoproterozoic St Simeon dolerite dykes, Quebec: an eastern Laurentian perspective of Ediacaran Rodinia breakup

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Pisarevsky, Sergei; Murphy, Brendan; Hamilton, Mike; Söderlund, Ulf; Hodych, Joseph

2013-04-01

The St Simeon (SS) mafic dykes (150 km NE of Quebec City) are now dated at 548 ± 1 Ma (U-Pb; baddeleyite). This age is similar to a published LA-ICPMS zircon age of 550 ± 7 Ma for the Mt. St-Anselme (MS) basalts, which supports previous inferences of (i) a genetic relationship between them, (ii) the pene-contemporaneity of OIB-type mafic magmatism in East Laurentia and (iii) the existence of two late Ediacaran plumes that attended the final breakup of Rodinia and opening of the Iapetus Ocean and Tornquist Sea. Both the SS dykes and the MS basalts were sampled for paleomagnetic study. The paleomagnetic pole for SS is similar to the previously published pole for coeval basalts (Skinner Cove, SC) from Newfoundland. Unlike SC, the St Simeon pole represents rocks which are unambiguously coherent tectonically with the Laurentian Craton. This new pole is also coeval with high quality poles from the Winter Coast (Baltica) and provides paleomagnetic constraints on the history of the final breakup of Rodinia and opening of Eastern Iapetus and Tornquist Sea.

Geochemical, isotopic, and zircon (U-Pb, O, Hf isotopes) evidence for the magmatic sources of the volcano-plutonic Ollo de Sapo Formation, Central Iberia

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Montero, P.; Talavera, C.; Bea, F.

2017-07-01

The Ollo de Sapo Formation comprises variably metamorphosed felsic peraluminous volcanic rocks and highlevel granites that crop out over some 600km from the Cantabrian coast to central Spain in the northern part of the Central Iberian Zone. The Ollo de Sapo magmatism is not obviously connected with any major tectonic or metamorphic event so its origin is controversial. Some authors, based on trace-elements, have proposed that the Ollo de Sapo magmas originated in a supra-subduction setting but others, based on abnormally high zircon inheritance and field and structural data, favored a rifting environment. Here we present new oxygen and hafnium isotope data from the very characteristic Ollo the Sapo zircons, which in most cases, consist of ca. 485Ma rims and ca. 590-615Ma cores. We found that the Cambrian-Ordovician rims yielded unimodal distributions that cluster around ∂18O = 10, typical of S-type magmas formed from melting of altered crust. The Ediacaran cores, in contrast, cluster around ∂18O = 6.5, consistent with being arc-magmas. Rims and cores have the same average Hf isotope composition, but the rims are considerably more uniform. These data, coupled with existing wholerock element and Sr and Nd isotopic data, indicate that the Ollo de Sapo were S-type magmas that resulted from anatexis of younger-than-600Ma immature sediments mostly derived from different Ediacaran igneous rocks with a wide range of Hf isotope composition.

Geochemical, isotopic, and zircon (U-Pb, O, Hf isotopes) evidence for the magmatic sources of the volcano-plutonic Ollo de Sapo Formation, Central Iberia

International Nuclear Information System (INIS)

Montero, P.; Talavera, C.; Bea, F.

2017-01-01

The Ollo de Sapo Formation comprises variably metamorphosed felsic peraluminous volcanic rocks and highlevel granites that crop out over some 600km from the Cantabrian coast to central Spain in the northern part of the Central Iberian Zone. The Ollo de Sapo magmatism is not obviously connected with any major tectonic or metamorphic event so its origin is controversial. Some authors, based on trace-elements, have proposed that the Ollo de Sapo magmas originated in a supra-subduction setting but others, based on abnormally high zircon inheritance and field and structural data, favored a rifting environment. Here we present new oxygen and hafnium isotope data from the very characteristic Ollo the Sapo zircons, which in most cases, consist of ca. 485Ma rims and ca. 590-615Ma cores. We found that the Cambrian-Ordovician rims yielded unimodal distributions that cluster around ∂18O = 10, typical of S-type magmas formed from melting of altered crust. The Ediacaran cores, in contrast, cluster around ∂18O = 6.5, consistent with being arc-magmas. Rims and cores have the same average Hf isotope composition, but the rims are considerably more uniform. These data, coupled with existing wholerock element and Sr and Nd isotopic data, indicate that the Ollo de Sapo were S-type magmas that resulted from anatexis of younger-than-600Ma immature sediments mostly derived from different Ediacaran igneous rocks with a wide range of Hf isotope composition.

U-Pb zircon and 40Ar/39Ar geochronology of sericite from hydrothermal alteration zones: new constraints for the timing of Ediacaran gold mineralization in the Sukhaybarat area, western Afif terrane, Saudi Arabia

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Harbi, Hesham M.; Ali, Kamal A.; McNaughton, Neal J.; Andresen, Arild

2018-04-01

The Sukhaybarat East and Red Hill deposits, in the northeastern part of the Arabian Shield, are mesothermal vein-type gold deposits hosted by late Cryogenian-Ediacaran intrusive rocks of the Idah suites (diorite, tonalite, granodiorite) and, at Sukhaybarat East, also by Ediacaran metasedimentary rocks. Gold mineralization comprises quartz-arsenopyrite veins (Sukhaybarat East), quartz-carbonate-pyrite veins (Red Hill), and subordinate gold-base metal sulfide veins. In the Red Hill deposit, alteration is complicated due to multiple overprinting hydrothermal events and is characteristically affected by pervasive, pink quartz-K-feldspar-hematite alteration which is overprinted by potassic alteration characterized by a quartz-biotite-carbonate-muscovite/sericite-rutile-apatite assemblage. This assemblage is associated with molybdenite veins which appear to form late in the paragenetic sequence and may represent either evolution of the ore fluid composition, or a later, unrelated mineralized fluids. Hydrothermal alteration at the Sukhaybarat East deposit is dominated by quartz-carbonate-sericite-arsenopyrite assemblages. Zircon from ore-hosting tonalite at Sukhaybarat East yields a U-Pb age of 629 ± 6 Ma, and biotite from the same rock gives an 40Ar/39Ar age of 622 ± 23 Ma. The 40Ar/39Ar age is within the uncertainty range for the U-Pb age of the host intrusion and is interpreted as a minimally disturbed cooling age for the tonalite. In the Red Hill area, granodiorite was emplaced at 615 ± 5 Ma, whereas muscovite/sericite separated from a mineralized sample of a quartz-carbonate-pyrite vein, that was overprinted by molybdenite-bearing veinlets, yields an 40Ar/39Ar age of 597 ± 8 Ma. We interpreted this age to represent the maximum age of the molybdenite mineralization and the probable minimum age of gold mineralization in the Red Hill deposit.

Ichnologic evidence of a Cambrian age in the southern Amazon Craton: Implications for the onset of the Western Gondwana history

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Santos, Hudson P.; Mángano, M. Gabriela; Soares, Joelson L.; Nogueira, Afonso C. R.; Bandeira, José; Rudnitzki, Isaac D.

2017-07-01

Colonization of the infaunal ecospace by burrowing bilaterians is one of the most important behavioral innovations during the Ediacaran-Cambrian transition. The establishment of vertical burrows by suspension feeders in high-energy nearshore settings during Cambrian Age 2 is reflected by the appearance of the Skolithos Ichnofacies. For the first time, unquestionable vertical burrows typical of the Skolithos Ichnofacies, such as Skolithos linearis, Diplocraterion parallelum and Arenicolites isp., are recorded from nearshore siliciclastic deposits of the Raizama Formation, southeastern Amazon Craton, Brazil. Integration of ichnologic and sedimentologic datasets suggests that these trace fossils record colonization of high-energy and well-oxygenated nearshore sandy environments. Chronostratigraphically, the presence of these vertical burrows indicates an age not older than early Cambrian for the Raizama Formation, which traditionally has been regarded as Ediacaran. Therefore, the Raizama ichnofauna illustrates the advent of modern Phanerozoic ecology marked by the Agronomic Revolution. The discovery of the Skolithos Ichnofacies in these shallow-marine strata suggests possible connections between some central Western Gondwana basins.

Physical volcanology, geochemistry and basin evolution of the Ediacaran volcano-sedimentary succession in the Bas Draâ inlier (Ouarzazate Supergroup, Western Anti-Atlas, Morocco)

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Karaoui, Brahim; Breitkreuz, Christoph; Mahmoudi, Abdelkader; Youbi, Nasrrddine

2014-11-01

New geologic mapping, lithofacies and granulometric analysis, and geochemistry from the volcano-sedimentary successions of the central part of the Bas Draâ inlier, Western Anti-Atlas, constrain the Ediacaran Ouarzazate Supergroup evolution during the post-collisional stage of the Pan-African orogeny. Volcanosedimentary facies analysis is the key aspect of the present contribution. We distinguished sixteen terrestrial volcanosedimentary lithofacies in the Bas Draâ succession (BDS), which reaches a total thickness of 2000 m. BDS evolution can be grouped into four units (Aouinet Aït Oussa I to IV, AO I-AO IV). The earliest volcanic activity produced rhyolitic ignimbrite sheets (AO I), which had been considered as lava flows by previous workers, and which were presumably related to caldera system(s). During AO II, a complex of high-silica andesitic and rhyolitic lavas formed, punctuated by the explosive eruption of a high-temperature silica-rich magma leading to the formation of parataxitic ignimbrite. AO III consists of basalt and andesite lava fields and small explosive, in parts phreatomagmatic volcanic vents. It is dissected by fluvial systems depositing external non-volcanic and local volcanic debris. BDS evolution terminated with the formation of a large SiO2-rich lava dome complex (AO IV), accompanied by small basalt effusive event. Volcanosedimentary facies analysis infers that the BDS evolved in a continental extensional setting developing in a low topography under humid paleoclimatic conditions. Alteration textures are dominated by a piemontite-calcite-albite-quartz (+ iron oxides) assemblage. Chemical analysis of BDS volcanic and subvolcanic rocks belongs to high-k calc-alkaline and alkali-calcic to alkaline magmatic trend typical for a post-collision setting. Trace elements spidergrams show a pattern typical for subduction-related suites of orogenic belts. REE patterns show moderate enrichment in LREE relative to flat HREE, with strong negative Eu

Neoproterozoic stratigraphic framework of the Tarim Craton in NW China: Implications for rift evolution

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Wu, Lin; Guan, Shuwei; Zhang, Shuichang; Yang, Haijun; Jin, Jiuqiang; Zhang, Xiaodan; Zhang, Chunyu

2018-06-01

The Tarim Craton is overlain by thick Neoproterozoic sedimentary successions in rift tectonic setting. This study examines the latest outcrop, seismic, and drilling core data with the objective of investigating the regional stratigraphy to deeply recognize the evolution of rifting in the craton. Cryogenian to Lower Ediacaran successions are mainly composed of clastic rocks with thicknesses of 2000-3000 m, and the Upper Ediacaran successions are composed of carbonate rocks with thicknesses of 500-800 m. The rift basins and stratigraphic zones are divided into northern and southern parts by a central paleo-uplift. The northern rift basin extends through the northern Tarim Craton in an E-W direction with two depocenters (Aksu and Kuruktag). The southern rift basin is oriented NE-SW. There are three or four phases of tillites in the northern zone, while there are two in the southern zone. Given the north-south difference of the stratigraphic framework, the northern rift basin initiated at ca. 740 Ma and the southern rift basin initiated at ca. 780 Ma. During the Cryogenian and Ediacaran, the northern and southern rift basins were separated by the central paleo-uplift, finally connecting with each other in the early Cambrian. Tectonic deformation in the Late Ediacaran led to the formation of a parallel unconformity in the rift basins and an angular unconformity in the central paleo-uplift. The Neoproterozoic rift basins continued to affect the distribution of Lower Cambrian hydrocarbon source rocks. The north-south distribution and evolution of the rift basins in the Tarim Craton have implications for reconstructions of the Rodinia supercontinent.

The Early Cambrian Mianyang-Changning Intracratonic Sag and Its Control on Petroleum Accumulation in the Sichuan Basin, China

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Shugen Liu

2017-01-01

Full Text Available The older and deeper hydrocarbon accumulations receive increasing attention across the world, providing more technical and commercial challenges to hydrocarbon exploration. We present a study of an asymmetrical, N-S striking intracratonic sag which developed across the Sichuan basin, south China, from Late Ediacaran to Early Cambrian times. The Mianyang-Changning intracratonic sag is ~50 km wide, with its steepest part in the basin center. In particular the eastern margin shows its greatest steepness. Five episodes in the evolutions of the sag can be recognized. It begins in the Late Ediacaran with an uplift and erosion correlated to Tongwan movement. Initial extension occurred during the Early Cambrian Maidiping period, when more strata of the Maidiping Formation were deposited across the sag. Subsequently, maximum extension occurred during the Early Cambrian Qiongzhusi period that resulted in 450–1700 m thick Maidiping-Canglangpu Formations being deposited in the sag. Then, the sag disappeared at the Longwangmiao period, as it was infilled by the sediments. The intracratonic sag has significant influence on the development of high-quality reservoirs in the Dengying and Longwangmiao Formations and source-rock of the Niutitang Formation. It thus indicates that a high probability for oil/gas accumulation exists along the intracratonic sag, across the central Sichuan basin.

The Ediacaran volcanic rocks and associated mafic dykes of the Ouarzazate Group (Anti-Atlas, Morocco): Clinopyroxene composition, whole-rock geochemistry and Sr-Nd isotopes constraints from the Ouzellarh-Siroua salient (Tifnoute valley)

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Belkacim, Said; Gasquet, Dominique; Liégeois, Jean-Paul; Arai, Shoji; Gahlan, Hisham A.; Ahmed, Hassan; Ishida, Yoshito; Ikenne, Moha

2017-03-01

Belonging to the huge Ouarzazate volcanic Group that covered the whole Anti-Atlas during the late Ediacaran (580-545 Ma), the Tifnoute valley volcanic formations are mainly pyroclastic and show a large composition, from trachybasalt to rhyolite and are crosscut by dolerite dykes. The Tifnoute valley volcanic rocks are located within a rigid salient of the Anti-Atlas that gives them special extreme characteristics. Due to the heavy greenschist alteration that affects this volcanic group, we focused the more immobile elements, but as REE can also be affected, we used the composition of unaltered clinopyroxene crystals to determine the nature of these volcanic rocks. The clinopyroxene is an augite diopside in the basalt, an augite in the andesite and an augite-salite in the dolerite. Petrography of the Tifnoute mafic volcanic rocks and clinopyroxene compositions indicate the presence of two magmatic series: (i) older high-K calc-alkaline (alkali-calcic) andesite and basalt characterized by the early crystallization of Fe-Ti oxides and of the late fractionation of plagioclase, the modal proportion of the latter increasing from the basalt to the andesite and (ii) younger alkalic dolerite dykes. With clinopyroxene trace element compositions obtained using laser ablation ICP-MS, we calculated the composition of the melts in equilibrium with the pyroxenes. The volcanic rocks of the Tifnoute Valley have positive εNd570 (+1.7 to +5.0), low Sri (volcanic rocks emplaced in a Pan-African transtensive post-collisional environment that evolved towards the major rifting event that will give rise to the Rheic ocean, in a similar way to what occurred just after the Variscan orogeny during the Triassic period that evolved to the Tethys ocean opening.

Ediacaran to Cambrian magmatic suites in the Rio Grande do Norte domain, extreme Northeastern Borborema Province (NE of Brazil): Current knowledge

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do Nascimento, Marcos Antonio Leite; Galindo, Antonio Carlos; de Medeiros, Vladimir Cruz

2015-03-01

The Ediacaran-Cambrian plutonic activity is one of the most important geological features of the Rio Grande do Norte Domain (Borborema Province, NE Brazil). It is represented by several batholiths, stocks and dykes. Based on the petrographic, geochemical and geochronological characteristic of different rocks, this plutonic activity can be grouped in six separate suites: shoshonitic (Shos), porphyritic high-K calc-alkaline (PHKCalcAlk), equigranular high K calc-alkaline (EHKCalcAlk), calc-alkaline (CalcAlk), alkaline (Alk) and charnockitic alkaline (ChAlk). Geochemically, the Shos, CalcAlk and Alk suites are differentiated from the others, while ChAlc can be distinguished from the others in some diagrams. The greatest difficulty lies in distinguishing between the chemically similar PHKCalcAlk and EHKCalcAlk. To this end, existing geochronological data as well as related petrographic and textural field aspects may be used to distinguish the two mentioned suites (PHKCalcAlk and EHKCalcAlk). Petrographically, the Shos suite has composition between gabbro/diorite and quartz monzonite. Monzogranites (with subordinate granodiorites and quartz monzonites) predominate in both PHKCalcAlk and EHKCalcAlk. Calc is composed of granodiorites to tonalites. Alc is formed by alkali feldspar granites (with subordinate alkali feldspar quartz syenites and syenogranites), whereas ChAlc has quartz mangerites and charnockites. The suites were emplaced between the Ediacaran (635-541 Ma) and Cambrian (541-485 Ma), predominantly in the Ediacaran, based on 34 U-Pb datings (zircon, titanite, monazite and columbite-tantalite), 17 Rb-Sr (whole rock) and 1 Sm-Nd (total rock and mineral) internal isochrons. The Shos suite has U-Pb ages varying from 599 ± 16 (Poço Verde pluton) to 579 ± 7 (Acari and São João do Sabugi plutons), slightly older than those of the PHKCalcAlk suite, which ranges between 591 ± 4 Ma (Totoró pluton) and 544 ± 7 Ma (São José de Espinharas pluton). The Calc

Syn-rift unconformities punctuating the lower-middle Cambrian transition in the Atlas Rift, Morocco

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Álvaro, J. Javier; Ezzouhairi, Hassan; Clausen, Sébastien; Ribeiro, M. Luisa; Solá, Rita

2015-04-01

The Cambrian Tamdroust and Bab n'Ali Volcanic Complexes represent two magmatic episodes developed in the latest Ediacaran-Cambrian Atlas Rift of Morocco. Their rifting pulses were accompanied by accumulation of volcanosedimentary edifices (dominated by effusive lava flows in the former and explosive acidic aprons in the latter) associated with active tilting and uplift. Sealing of their peneplaned horst-and-graben palaeotopographies led to the onset of distinct onlapping geometries and angular discordances capping eroded basements ranging from the Ediacaran Ouarzazate Supergroup to the Cambrian Asrir Formation. Previous interpretations of these discordances as pull-apart or compressive events are revised here and reinterpreted in an extensional (rifting) context associated with active volcanism. The record of erosive unconformities, stratigraphic gaps, condensed beds and onlapping patterns across the traditional "lower-middle Cambrian" (or Cambrian Series 2-3) transition of the Atlas Rift must be taken into consideration for global chronostratigraphic correlation based on their trilobite content.

1 Observations on the ichnospecies Monomorphichnus multilineatus ...

Indian Academy of Sciences (India)

24

The Ediacaran-Cambrian Marwar Supergroup exposed in the western Rajasthan ... Small Shelly Fauna (SSF) represented by ichnofossils and body fossils ... global distribution of genus Monomorphichnus, mode of preservation, size ...... Ediacaran Jodhpur Sandstone, Marwar Supergroup, western Rajasthan; J. Asian Earth.

Neoproterozoic rift basins and their control on the development of hydrocarbon source rocks in the Tarim Basin, NW China

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Zhu, Guang-You; Ren, Rong; Chen, Fei-Ran; Li, Ting-Ting; Chen, Yong-Quan

2017-12-01

The Proterozoic is demonstrated to be an important period for global petroleum systems. Few exploration breakthroughs, however, have been obtained on the system in the Tarim Basin, NW China. Outcrop, drilling, and seismic data are integrated in this paper to focus on the Neoproterozoic rift basins and related hydrocarbon source rocks in the Tarim Basin. The basin consists of Cryogenian to Ediacaran rifts showing a distribution of N-S differentiation. Compared to the Cryogenian basins, those of the Ediacaran are characterized by deposits in small thickness and wide distribution. Thus, the rifts have a typical dual structure, namely the Cryogenian rifting and Ediacaran depression phases that reveal distinct structural and sedimentary characteristics. The Cryogenian rifting basins are dominated by a series of grabens or half grabens, which have a wedge-shaped rapid filling structure. The basins evolved into Ediacaran depression when the rifting and magmatic activities diminished, and extensive overlapping sedimentation occurred. The distributions of the source rocks are controlled by the Neoproterozoic rifts as follows. The present outcrops lie mostly at the margins of the Cryogenian rifting basins where the rapid deposition dominates and the argillaceous rocks have low total organic carbon (TOC) contents; however, the source rocks with high TOC contents should develop in the center of the basins. The Ediacaran source rocks formed in deep water environment of the stable depressions evolving from the previous rifting basins, and are thus more widespread in the Tarim Basin. The confirmation of the Cryogenian to Ediacaran source rocks would open up a new field for the deep hydrocarbon exploration in the Tarim Basin.

Evolution and estimated age of the C5 Lukala carbonate-evaporite ramp complex in the Lower Congo region (Democratic Republic of Congo): New perspectives in Central Africa

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Delpomdor, F.; Van Vliet, N.; Devleeschouwer, X.; Tack, L.; Préat, A.

2018-01-01

New detailed lithological, sedimentological, chemostratigraphic data were obtained from exploration drilling samples on the C5 carbonate-dominated formation of the Neoproterozoic Lukala Subgroup (former Schisto-Calcaire Subgroup) from the West Congo Belt (WCB) in the Democratic Republic of Congo. This formation records the last post-Marinoan sea-level events that occurred in the whole basin, followed by the development of the Araçuaï-West Congo Orogen between 630 and 560 Ma. The C5 Formation consists of back-reef lagoonal and peritidal/sabkha cycles of ∼2.0 m in thickness, that record a short-time marine regression, rapidly flooded by a marine transgression with deposition of organic-rich argillaceous carbonates or shales under dysoxia and anoxia conditions. These dysoxic/anoxic waters were rapidly followed by a regional-scale marine transgression, favouring mixing with well-oxygenated waters, and the development of benthic Tonian to Cambro-Ordovician Obruchevella parva-type 'seagrasses' in the nearshore zones of the lagoons. New δ13C and 87Sr/86Sr isotopic data in the C5 Formation of the Lukala Subgroup are used in the frame of a correlation with the Sete Lagoas Formation in Brazil. Relatively comparable negative to positive δ13C excursions point to marine flooding of the whole basin and allow extension of the debatable Late Ediacaran age of the uppermost Sete Lagoas and C5 formations. Sr isotope ;blind dating; failed due to low Sr concentration related to a dolomitization event close 540 Ma. Several tentative datings of the C5 Formation converge to a Late Ediacaran age ranging between 575 and 540 Ma. As the overlying Mpioka folded Subgroup, the C5 series suffered the Pan African deformation, dated at 566 ± 42 Ma. Unlike the previously generally accepted interpretation, our data suggests that the Mpioka Subgroup was deposited in the Early Cambrian.

Hydrogeological feature and recharge factors of Baofengyuan uranium deposit in north Jiangxi

International Nuclear Information System (INIS)

He Xiaomei

2013-01-01

Baofengyuan uranium deposit is a typical carbonaceous-siliceous-argillaceous rock one in China. The groundwater in the deposit distributed like layers which are mainly interlayer structure fracture confined water and structure solution cave fracture confined water in the third and fourth layer of Wangyinpu formation of Cambrian and the third and second layer of Dengying formation and Doushantuo formation of Sinian. The mineralization bed is basically coherent with the aquifer. In the area, geologic structures are fairly complicated, the groundwater between aquifers are probably connected with leakage and diversion structures. In the west side of structure F8, the deposit is recharged mainly by interlayer structure solution cave fissure confined water of rich source, and in the east side of structure F8, the deposit is recharged by interlayer structure fissure confined water of poor source. Before mining the deposit, the hydrogeological evaluation must be performed to accurately ascertain the diversion structure position, analysis the weak location of the top and bottom watertight stratum of the ore-bearing bed so as to provide a basis for waterproof security. (author)

Recognized Multiple Rifts of the Neoproterozoic in the Initiation of the Tarim Craton (NW China) and Their Tectonic Implications

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He, B.; Jiao, C.; Huang, T.; Zhou, X.; Cai, Z.; Cao, Z.; Jiang, Z.; Cui, J.; Yu, Z.; Chen, W.

2017-12-01

The Tarim Basin is the largest, oil-bearing and superimposed basin in the northwest of China. The development and tectonic property of the initial Tarim basin have been acutely disputed and remain enigmatic. Urgently need to reveal the origin and formation dynamics of the Tarim Carton and evaluate the potential of the deep energy resources. However, covered by vast desert and huge-thickness sedimentary strata, suffered by multiple tectonic movements, seismic data with low signal- to- noise ratio in the deep are the critical difficulties. We analyse 4 field outcrops, 18 wells, 27 reprocessed seismic reflection profiles with high SNR across the basin and many ancillary ones and aeromagnetic data. We find about 20 normal fault-controlled rift depressions of the Cryogenian and Ediacaran scattered in the Tarim basin, which developed on the Precambrian metamorphic and crystalline basements and covered by the epeiric sea and basin facies sediments of the Lower Cambrian. The structural styles of the rifts are mainly half grabens, symmetrical troughs and horst-grabens. The regional differences exist obviously in spatial and temporal. The WNW-ESE-trending faults occur in the central part and northern of the basin and the NE, and the NEE-trending faults occur in the southern parts, which response with the anomaly of aeromagnetic. Some main faults of the Ediacaran inherited from the Cryogenian and some occurred newly, the more rifting depressions occurred during the Ediacaran. The extensional NNW-SSE-oriented and NNE-SSW-oriented paleostress field occurred simultaneously during rifting, and accompanied with the clockwise shearing. According to the activities of syn-sedimentary faults, magmatic events and sediments, the tectonic properties of the rifts are different depending on their locations in the Tarim craton. The rifting phases mainly occurred from 780 Ma to 615 Ma. The formation of rifts were associated with the opening of the South Tianshan Ocean and the South Altun

Magnetic fabric and flow direction in the Ediacaran Imider dyke swarms (Eastern Anti-Atlas, Morocco), inferred from the Anisotropy of Magnetic Susceptibility (AMS)

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Otmane, Khadija; Errami, Ezzoura; Olivier, Philippe; Berger, Julien; Triantafyllou, Antoine; Ennih, Nasser

2018-03-01

Located in the Imiter Inlier (Eastern Saghro, Anti-Atlas, Morocco), Ediacaran volcanic dykes have been studied for their petrofabric using Anisotropy of Magnetic Susceptibility (AMS) technique. Four dykes, namely TF, TD, FF and FE show andesitic compositions and are considered to belong to the same dyke swarm. They are oriented respectively N25E, N40E, N50E, and N10E and have been emplaced during a first tectonic event. The dyke FW, oriented N90E displays a composition of alkali basalt and its emplacement is attributed to a subsequent tectonic event. These rocks are propylitized under greenschist facies conditions forming a secondary paragenesis constituted by calcite, chlorite, epidote and sericite. The dykes TF, TD, FF and FE are sub-volcanic calc-alkaline, typical of post-collisional basalts/andesites, belonging to plate margin andesites. The FW dyke shows a within-plate basalt signature; alkaline affinity reflecting a different petrogenetic process. The thermomagnetic analyses show a dominantly ferromagnetic behaviour in the TF dyke core carried by single domain Ti-poor magnetite, maghemite and pyrrhotite. The dominantly paramagnetic susceptibilities in TF dyke rims and TD, FE, FF and FW dykes are controlled by ilmenite, amphibole, pyroxene and chlorite. The magnetic fabrics of the Imider dykes, determined by our AMS study, allows us to reconstitute the tectonic conditions which prevailed during the emplacement of these two generations of volcanic dykes. The first tectonic event was characterized by a roughly NE-SW compression and the second tectonic event is characterized by an E-W shortening followed by a relaxation recording the end of the Pan-African orogeny in the eastern Anti-Atlas.

The role of microbial iron reduction in the formation of Proterozoic molar tooth structures

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Hodgskiss, Malcolm S. W.; Kunzmann, Marcus; Poirier, André; Halverson, Galen P.

2018-01-01

Molar tooth structures are poorly understood early diagenetic, microspar-filled voids in clay-rich carbonate sediments. They are a common structure in sedimentary successions dating from 2600-720 Ma, but do not occur in rocks older or younger, with the exception of two isolated Ediacaran occurrences. Despite being locally volumetrically significant in carbonate rocks of this age, their formation and disappearance in the geological record remain enigmatic. Here we present iron isotope data, supported by carbon and oxygen isotopes, major and minor element concentrations, and total organic carbon and sulphur contents for 87 samples from units in ten different basins spanning ca. 1900-635 Ma. The iron isotope composition of molar tooth structures is almost always lighter (modal depletion of 2‰) than the carbonate or residue components in the host sediment. We interpret the isotopically light iron in molar tooth structures to have been produced by dissimilatory iron reduction utilising Fe-rich smectites and Fe-oxyhydroxides in the upper sediment column. The microbial conversion of smectite to illite results in a volume reduction of clay minerals (∼30%) while simultaneously increasing pore water alkalinity. When coupled with wave loading, this biogeochemical process is a viable mechanism to produce voids and subsequently precipitate carbonate minerals. The disappearance of molar tooth structures in the mid-Neoproterozoic is likely linked to a combination of a decrease in smectite abundance, a decline in the marine DIC reservoir, and an increase in the concentration of O2 in shallow seawater.

Origin and implications of a thrust-bound gypsiferous unit along the western edge of Jabal Sumeini, northern Oman Mountains

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Cooper, David J. W.; Ali, Mohammed Y.; Searle, Michael P.

2018-04-01

The Oman Mountains comprise a series of thrust sheets of Neo-Tethyan oceanic rocks that were emplaced onto the Arabian continental margin during obduction of the Semail Ophiolite during the Late Cretaceous. Three separate groups of anomalous gypsiferous bodies intrude the allochthonous units along faults over a distance of about 150 km in the Hawasina Window, Jabal Qumayrah and Jabal Sumeini. The bodies at Jabal Sumeini form a band about 4 km long and up to 100 m wide along a late-stage thrust that restacks the allochthon over a post-emplacement Maastrichtian-Palaeogene sedimentary succession. The gypsum shows evidence of flow-folding and contains numerous clasts and rafts of a range of quartzose sandstones, but with only a minor component from carbonates from the Neo-Tethyan Sumeini Group in the hanging-wall. Palaeogene limestones from the footwall succession are essentially absent. Strontium isotope ratios are high and intersect with the open ocean-water reference curve for the Late Cambrian-Ordovician and Late Miocene-Pliocene. They are also noticeably higher than the ratios from the two other gypsiferous outcrop areas in the Oman Mountains and from outcrops of Ediacaran-Early Cambrian salt domes in central Oman. However, the regional stratigraphy points towards a source of the gypsum from either an Ediacaran-Early Cambrian Ara Group salt basin or from the Lower Fars Formation (Early-Middle Miocene), and derivation of the sandstone clasts and rafts from thick Lower Palaeozoic clastic sequences. The discrepancy with the ages inferred from the strontium isotope data can be attributed to deposition of the gypsum in restricted conditions not in equilibrium with the prevailing ocean water. Two models are presented, for an Ediacaran-Early Cambrian and an Early-Middle Miocene source. While the latter cannot be wholly discounted, the stratigraphic and structural context point more strongly towards an Ediacaran-Early Cambrian Ara Group source of the gypsum. This was

There is no such thing as the ‘Ediacara Biota’

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Breandán Anraoi MacGabhann

2014-01-01

Full Text Available The term ‘Ediacara Biota’ (or many variants thereof is commonly used to refer to certain megascopic fossils of Precambrian and early Palaeozoic age – but what does the term actually mean? What differentiates a non-Ediacaran ‘Ediacaran’ and an Ediacaran ‘Ediacaran’ from an Ediacaran non-‘Ediacaran’? Historically, the term has been used in either a geographic, stratigraphic, taphonomic, or biologic sense. More recent research and new discoveries, however, mean that the term cannot actually be defined on any of these bases, or any combination thereof. Indeed, the term is now used and understood in a manner which is internally inconsistent, and unintentionally implies that these fossils are somehow distinct from other fossil assemblages, which is simply not the case. Continued use of the term is a historical relic, which has led in part to incorrect assumptions that the ‘Ediacara Biota’ can be treated as a single coherent group, has obscured our understanding of the biological change over the Precambrian–Cambrian boundary, and has confused research on the early evolution of the Metazoa. In the future, the term ‘Ediacaran’ should be restricted to purely stratigraphic usage, regardless of affinity, geography, or taphonomy; sufficient terminology also exists where reference to specimens on a geographic, taphonomic, or biologic basis is required. It is therefore time to abandon the term ‘Ediacara Biota’ and to instead treat equally all of the fossils of the Ediacaran System.

U-Pb age constraints for the La Tuna Granite and Montevideo Formation (Paleoproterozoic, Uruguay): Unravelling the structure of the Río de la Plata Craton

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Pamoukaghlián, Karina; Gaucher, Claudio; Frei, Robert; Poiré, Daniel G.; Chemale, Farid; Frei, Dirk; Will, Thomas M.

2017-11-01

The Río de la Plata Craton is a continental block that crops out in Uruguay, eastern Argentina, southernmost Brazil and Paraguay. It comprises in Uruguay the Piedra Alta, Tandilia and Nico Pérez terranes, separated by the Colonia and the Sarandí del Yí megashears. The La Tuna Granite, which intrudes the Araminda metasandstones in the Tandilia Terrane, was considered Cambrian in age and the intruded sandstones were assigned to the Neoproterozoic Piedras de Afilar Formation. We show that the granite is Paleoproterozoic in age and that the host metasandstones do not belong to the Piedras de Afilar Formation, but to the Paleoproterozoic Montevideo Formation. U-Pb LA ICP-MS of zircon ages for the La Tuna Granite yielded a concordant crystallization age of 2156 ± 26 Ma. Furthermore a metamorphic event at 2010 ± 9 Ma is revealed by Pb stepwise leaching dating of monazites. U-Pb detrital zircon ages of the host Araminda metasandstone yield an upper intercept discordia age of 2152 ± 29 Ma, which marks the intrusion of the La Tuna pluton, and which is in accordance with the zircon U-Pb LA ICP MS constraints. A concordant U-Pb detrital zircon age of 2465 ± 40 Ma provides a maximum depositional age constraint for the metapsammites. Comparing quartz arenites of the Ediacaran Piedras de Afilar Formation with the Araminda metaquartzites, we conclude that they are very similar regarding petrology but they differ in age and metamorphic overprint. Detrital zircons in quartz arenites of the Piedras de Afilar Formation show youngest ages of 1.0 Ga. On the other hand, detrital zircons recovered from the Araminda metasandstones and the age of the intruding granite allow interpreting a depositional age between 2465 and 2150 Ma. Nd model ages show crustal residence times in average more than 200 myr older for the Tandilia Terrane both in Uruguay and Argentina, with a significant Neoarchean component, which is lacking in the Piedra Alta Terrane. Whereas the Piedra Alta Terrane was

New paleomagnetic data from Siberia: Non-uniformitarian geomagnetic field around the Proterozoic-Phanerozoic boundary?

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Pavlov, V.; Shatsillo, A.; Kouznetsov, N.; Gazieva, E.

2017-12-01

There is a range of evidence, mainly from sedimentary and volcanic rocks of the Laurentia and Baltica cratons, that argue for the anomalous character of the Ediacaran-Early Cambrian paleomagnetic record. This feature could be linked either to some peculiarities of the paleomagnetic record itself or to some unusual geophysical event that would have taken place around the Proterozoic-Phanerozoic boundary (e.g., true polar wander or nonuniformitarian geomagnetic field behavior). In the latter case, the traces of this event should be observed in Ediacaran-Early Cambrian rocks anywhere there is a possibility to observe a primary paleomagnetic signal. In previous work, we reported results that suggested an anomalous paleomagnetic record in Siberian Ediacaran-Lower Cambrian rocks. Here we present new Siberian data that indicate a very high geomagnetic reversal frequency during this period and the coexistence of two very different paleomagnetic directions. We speculate that these features could be due either to a near-equatorial geomagnetic dipole during the polarity transitions or to alternation between axial and near equatorial dipoles not directly linked with polarity reversals.

Multiscale approach reveals that Cloudina aggregates are detritus and not in situ reef constructions

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Mehra, Akshay; Maloof, Adam

2018-03-01

The earliest metazoans capable of biomineralization appeared during the late Ediacaran Period (635–541 Ma) in strata associated with shallow water microbial reefs. It has been suggested that some Ediacaran microbial reefs were dominated (and possibly built) by an abundant and globally distributed tubular organism known as Cloudina. If true, this interpretation implies that metazoan framework reef building—a complex behavior that is responsible for some of the largest bioconstructions and most diverse environments in modern oceans—emerged much earlier than previously thought. Here, we present 3D reconstructions of Cloudina populations, produced using an automated serial grinding and imaging system coupled with a recently developed neural network image classifier. Our reconstructions show that Cloudina aggregates are composed of transported remains while detailed field observations demonstrate that the studied reef outcrops contain only detrital Cloudina buildups, suggesting that Cloudina played a minor role in Ediacaran reef systems. These techniques have wide applicability to problems that require 3D reconstructions where physical separation is impossible and a lack of density contrast precludes tomographic imaging techniques.

An autochthonous Avalonian basement source for the latest Ordovician Brenton Pluton in the Meguma terrane of Nova Scotia: U-Pb-Hf isotopic constraints and paleogeographic implications

Science.gov (United States)

Duncan Keppie, J.; Gregory Shellnutt, J.; Dostal, Jaroslav; Fraser Keppie, D.

2018-04-01

The Ediacaran-Ordovician Meguma Supergroup was thrust over Avalonia basement prior to the intrusion of post-Acadian, ca. 370 Ma, S-type granitic batholiths. This has led to two main hypotheses regarding the original location of the Meguma terrane, a continental rise prism bordering either NW Africa or Avalonia. On the other hand, the pre-Acadian, ca. 440 Ma Brenton pluton has yielded the following U/Pb LA-ICP-MS zircon data: (1) 448 ± 3 Ma population peak inferred to be the intrusive age and (2) ca. 550 and 700 Ma inherited ages common to both Avalonia and NW Africa. In contrast, Hf isotopic analyses of zircon yielded model ages ranging from 814 to 1127 Ma with most between 940 and 1040 Ma: such ages are typical of Avalonia and not NW Africa. The ages of the inherited zircons found within the Brenton pluton suggest that it was probably derived by partial melting of sub-Meguma, mid-crustal Avalonian rocks, upon which the Meguma Supergroup was deposited. Although Avalonia is commonly included in the peri-Gondwanan terranes off NW Africa or Amazonia, paleomagnetic data, faunal provinciality, and Hf data suggest that, during the Ediacaran-Early Cambrian, it was an island chain lying near the tropics (ca. 20-30 °S) and was possibly a continuation of the Bolshezemel volcanic arc accreted to northern Baltica during the Ediacaran Timanide orogenesis. This is consistent with the similar derital zircon population in the Ediacaran-Cambrian Meguma Supergroup and the Dividal Group in northeastern Baltica.

Sedimentary provenance in the southern sector of the São Francisco Basin, SE Brazil

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Gustavo Macedo de Paula-Santos

Full Text Available ABSTRACT: We present new Sm-Nd, U-Pb and Hf isotope geochronological data for the siliciclastic rocks in the southern sector of the São Francisco Basin. An abrupt change in the Sm-Nd data is observed from the Carrancas Formation’s oligomitic conglomerates (TDM ages between 2.7 and 3.3 Ga; εNd(550 Ma values between -25.09 and -17.98, its finer facies, and the finer facies of the the Moema Laminite (TDM ages from 1.4 to 2.1 Ga; εNd(550 Ma values between -9.46 and -5.59. No further significant changes in the Sm-Nd data occur farther upwards in the Bambuí Group (Sm-Nd TDM ages within the 1.3-2.0 Ga interval; εNd(550 Ma values from -9.53 to -4.09, showing a lack of reorganization in the source areas throughout the deposition of the basin. This is yet another argument to dismiss an unconformity within the Bambuí Group. The presence of the index fossil Cloudina sp. in the lower Sete Lagoas Formation makes the glaciation probably Late Ediacaran in age. U-Pb ages for detrital zircons of the Bambuí Group range from the Archean to the early Ediacaran, but the current data is insufficient to distinguish between the contribution from sources in the Brasília and Araçuaí belts.

Cryptic Disc Structures Resembling Ediacaran Discoidal Fossils from the Lower Silurian Hellefjord Schist, Arctic Norway.

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Christopher L Kirkland

Full Text Available The Hellefjord Schist, a volcaniclastic psammite-pelite formation in the Caledonides of Arctic Norway contains discoidal impressions and apparent tube casts that share morphological and taphonomic similarities to Neoproterozoic stem-holdfast forms. U-Pb zircon geochronology on the host metasediment indicates it was deposited between 437 ± 2 and 439 ± 3 Ma, but also indicates that an inferred basal conglomerate to this formation must be part of an older stratigraphic element, as it is cross-cut by a 546 ± 4 Ma pegmatite. These results confirm that the Hellefjord Schist is separated from underlying older Proterozoic rocks by a thrust. It has previously been argued that the Cambrian Substrate Revolution destroyed the ecological niches that the Neoproterozoic frond-holdfasts organisms occupied. However, the discovery of these fossils in Silurian rocks demonstrates that the environment and substrate must have been similar enough to Neoproterozoic settings that frond-holdfast bodyplans were still ecologically viable some hundred million years later.

Temporal record of osmium concentrations and 187Os/188Os in organic-rich mudrocks: Implications for the osmium geochemical cycle and the use of osmium as a paleoceanographic tracer

Science.gov (United States)

Lu, Xinze; Kendall, Brian; Stein, Holly J.; Hannah, Judith L.

2017-11-01

We present a compilation of 192Os concentrations (representing non-radiogenic Os) and initial 187Os/188Os isotope ratios from organic-rich mudrocks (ORM) to explore the evolution of the Os geochemical cycle during the past three billion years. The initial 187Os/188Os isotope ratio of a Re-Os isochron regression for ORM constrains the local paleo-seawater 187Os/188Os, which is governed by the relative magnitudes of radiogenic Os (old continental crust) and unradiogenic Os (mantle, extraterrestrial, and juvenile/mafic/ultramafic crust) fluxes to seawater. A first-order increase in seawater 187Os/188Os ratios occurs from the Archean to the Phanerozoic, and may reflect a combination of increasing atmosphere-ocean oxygenation and weathering of progressively more radiogenic continental crust due to in-growth of 187Os from radioactive decay of 187Re. Superimposed on this long-term trend are shorter-term fluctuations in seawater 187Os/188Os ratios as a result of climate change, emplacement of large igneous provinces, bolide impacts, tectonic events, changes in seafloor spreading rates, and lithological changes in crustal terranes proximal to sites of ORM deposition. Ediacaran-Phanerozoic ORM have mildly higher 192Os concentrations overall compared with pre-Ediacaran Proterozoic ORM based on the mean and 95% confidence interval of 10,000 median values derived using a bootstrap analysis for each time bin (insufficient Archean data exist for robust statistical comparisons). However, there are two groups with anomalously high 192Os concentrations that are distinguished by their initial 187Os/188Os isotope ratios. Ediacaran-Cambrian ORM from South China have radiogenic initial 187Os/188Os, suggesting their high 192Os concentrations reflect proximal Os-rich crustal source(s), ultraslow sedimentation rates, and/or other unusual depositional conditions. In contrast, the unradiogenic initial 187Os/188Os and high 192Os concentrations of some Mesozoic ORM can be tied to emplacement

Origin of the Eastern Mediterranean: Neo-Tethys Rifting Along a Cryptic Cadomian Suture with Afro-Arabia

Science.gov (United States)

Avigad, D.; Abbo, A.; Gerdes, A.

2016-12-01

The East Mediterranean is a land-locked basin, a remnant of Neo-Tethys. It was formed in the Permo-Triassic as a result of the drift of the Tauride block from the Afro-Arabian margin of Gondwana. Herein we show that rather than being a genuine Afro-Arabia crustal fragment, the Tauride block is underlain by a Late Neoproterozoic Cadomian basement, which differs significantly from the Neoproterozoic "Pan-African" basement of NE Africa from which it was detached. Resembling other Cadomian terranes of Western Europe, the Tauride basement is chiefly a greywacke succession deposited in a mid to late Ediacaran back-arc basin formed on the periphery of Afro-Arabia, above the southward subducting proto-Tethys. The back-arc region was deformed and metamorphosed to various degrees and intruded by latest Ediacaran-Cambrian granites and volcanics during the Cadomian orogeny. Unlike the protracted (ca .300 m.y.) Neoproterozoic crustal evolution recorded in Afro-Arabia, the Cadomian basement of the Taurides evolved briefly, over ca. 50 m.y. We show that the entire cycle of sedimentation, metamorphism and magmatism in the Tauribe basement took place in the late Ediacaran-Cambrian and lagged after Neoproterozoic Pan-African orogeny and igneous activity in Afro-Arabia. The Cadomian orogeny had accreted the Taurides, and adjoining peri-Gandwana Cadomian terranes, with an already-consolidated Afro-Arabian continent. Permo-Triassic rifting of the East Mediterranean occurred close to the transition between these two domains. Rifting has thus been inherited from, and superimposed on late Ediacaran structures formed in front of the current Afro-Arabia margin of Gondwana during Cadomian orogeny. The boundary between the Cadomian edifice and the Pan-African crust of Afro-Arabia appears to lie nowadays on the southern margin of the Mediterranean, extending from Morocco in the west to Arabia in the east. Hence, the continental margin of the East Mediterranean, including in the Levant basin

Li tho bio chemistratrigraphy in Mina Verdum group Nico Perez terrain-Uruguay

International Nuclear Information System (INIS)

Gaucher, C.; Martinez, G.; Cernuschi, F.; Chiglino, L.; Sial, A.; Poire, D.

2007-01-01

The occurrence of volcanic and pyroclastic rocks in the Mina Verdun Group is reported here. The unit represents a marine volcanosedimentary succession, made up from base to top of the following formations: Cerro de las Viboras Formation (metarhyolites), Don Mario Formation (pelites, sandstones), La Toma Formation (marls), El Calabozo Formation (stromatolitic limestones with Conophyton), Gibraltar Formation (mainly dolostones, subordinate marls and limestones) and Nueva Carrara Formation (acid lapilli-tuffs acidos and dolomitic metamarls). Three outcrop areas are known, located between Minas and Pan de Azucar, namely: Mina Verdun (stratotype), Burgueno Quarry and Paso del Molino (Arroyo Pan de Azucar). Diamictites and orthoconglomerates of the Las Ventanas Formation overly with erosional and angular unconformity the Mina Verdun Group. The age of the succession is pre-Ediacaran, and bracketed between the late Mesoproterozoic and Tonian (1300-850 Ma) according to the chemostratigraphic data and the stromatolite assemblages. Carbonates of the Mina Verdun Group show a ?13C curve at its stratotype, which is characterized by a basal negative excursion to -3.3 PDB, followed by moderately positive values in the rest of the section, representing a plateau around +2 ? PDB. In the southern part of its outcrop area, limestones of the Mina Verdun Group show more negative de ?13C and ?18O values, as well as a maniphest decoloration. These characteristics are the result of contact-metamorphism of nearby granitic plutons in that area. (author)

Nejstarší doklad existence svalové tkáně? Nové zkameněliny z konce starohor

Czech Academy of Sciences Publication Activity Database

Mikuláš, Radek

2015-01-01

Roč. 94, č. 1 (2015), s. 31-34 ISSN 0042-4544 Institutional support: RVO:67985831 Keywords : paleontology * fossil s * Eumetazoa * Cnidaria * Bilateralia * Ediacaran fauna * Proterozoic * muscle tissue * fossil footprints * movement of animals Subject RIV: DB - Geology ; Mineralogy

Replacement of benthic communities in two Neoproterozoic-Cambrian subtropical-to-temperate rift basins, High Atlas and Anti-Atlas, Morocco

Science.gov (United States)

Clausen, Sébastien; Álvaro, J. Javier; Zamora, Samuel

2014-10-01

The ‘Cambrian explosion’ is often introduced as a major shift in benthic marine communities with a coeval decline of microbial consortia related to the diversification of metazoans and development of bioturbation (‘Agronomic Revolution’). Successive community replacements have been reported along with ecosystem diversification and increase in guild complexity from Neoproterozoic to Cambrian times. This process is recorded worldwide but with regional diachroneities, some of them directly controlled by the geodynamic conditions of sedimentary basins. The southern High Atlas and Anti-Atlas of Morocco record development of two rifts, Tonian (?) - early Cryogenian and latest Ediacarian-Cambrian in age, separated by the onset of the Pan-African Orogeny. This tectonically controlled, regional geodynamic change played a primary control on pattern and timing of benthic ecosystem replacements. Benthic communities include microbial consortia, archaeocyathan-thromboid reefal complexes, chancelloriid-echinoderm-sponge meadows, and deeper offshore echinoderm-dominated communities. Microbial consortia appeared in deeper parts of the Tonian (?) - early Cryogenian fluvio-deltaic progradational rift sequences, lacustrine environments of the Ediacaran Volcanic Atlasic Chain (Ouarzazate Supergroup) and the Ediacaran-Cambrian boundary interval, characterized by the peritidal-dominated Tifnout Member (Adoudou Formation). They persisted and were largely significant until Cambrian Age 3, as previous restricted marine conditions precluded the immigration of shelly metazoans in the relatively shallow epeiric parts of the Cambrian Atlas Rift. Successive Cambrian benthic communities were replaced as a result of distinct hydrodynamic and substrate conditions, which allow identification of biotic (e.g., antagonistic relationships between microbial consortia and echinoderms, and taphonomic feedback patterns in chancelloriid-echinoderm-sponge meadows) and abiotic (e.g., rifting

Edikarské mikrobiality z okolí Nového Knína (tepelsko-barrandienská oblast)

Czech Academy of Sciences Publication Activity Database

Vavrdová, Milada

2016-01-01

Roč. 49, č. 1 (2016), s. 37-41 ISSN 0514-8057 Institutional support: RVO:67985831 Keywords : Teplá-Barrandian Unit * Ediacaran * microbialites Subject RIV: DB - Geology ; Mineralogy http://www.geology.cz/img/zpravyvyzkum/fulltext/04_Vavrdova_160511.pdf

Geochronological constraints on the polycyclic magmatism in the Bou Azzer-El Graara inlier (Central Anti-Atlas Morocco)

Science.gov (United States)

Blein, O.; Baudin, T.; Chèvremont, P.; Soulaimani, A.; Admou, H.; Gasquet, P.; Cocherie, A.; Egal, E.; Youbi, N.; Razin, P.; Bouabdelli, M.; Gombert, P.

2014-11-01

New U-Pb SHRIMP zircon ages from the Bou Azzer-El Graara onlier constrains the Neoproterozoic evolution of the Anti-Atlas during Pan-African orogenesis. Within the Central Anti-Atlas, the Bou Azzer-El Graara inlier exposes a dismembered ophiolite, long considered to mark a late Neoproterozoic suture between the West African Craton in the south, and Neoproterozoic arcs to the north. From north to south, this inlier includes four main geological units: a volcanic-arc, an ophiolite, a metamorphic complex and a continental platform. Several plutons intrude the volcanic-arc, the ophiolite, the metamorphic complex, and post-orogenic volcanic and sedimentary deposits unconformably cover these terranes. The age of the volcanic-arc is reported here for the first time. Analyses of zircon of two rhyolites provide ages of 761 ± 7 Ma and 767 ± 7 Ma. Zircons from two gneisses provide dates of 755 ± 9 Ma and 745 ± 5 Ma. Both dates are considered best estimates of the crystallization ages of their igneous protoliths. Analyses of zircon from two granitic bodies, which crosscut gneisses, provide younger dates of 702 ± 5 Ma and 695 ± 7 Ma. The age of an aplitic body of the ophiolite is reported here for the first time, as 658 ± 8 Ma (SHRIMP U-Pb on zircons). Theses ages suggest the existence of three distinct orogenic events during Cryogenian times: (i) 770-760 Ma Tasriwine-Tichibanine orogeny with rollback of the subducting oceanic plate, leading to the formation of back-arc basins; (ii) 755-695 Ma Iriri-n'Bougmmane orogeny; and (iii) the 660-640 Ma Bou Azzer orogeny involving the formation and the emplacement of the Bou Azer ophiolite. During Ediacaran times, the Bou Azzer-El Graara inlier is characterized with the development of a continental volcanic arc between 630 and 580 Ma (Bou Lbarod Group, 625 ± 8 Ma; Bleïda granodiorite, 586 ± 15 Ma), and strike-slip pull-apart basins (Tiddiline Group, 606 ± 4 Ma and 606 ± 5 Ma). These volcanic and sedimentary Lower Ediacaran

Oxygen requirements of the earliest animals

DEFF Research Database (Denmark)

Mills, Daniel Brady; Ward, Lewis M.; Jones, CarriAyne

2014-01-01

likely exhibited a physiology and morphology similar to that of a modern sponge, its oxygen demands may have been met well before the enhanced oxygenation of the Ediacaran Period. Therefore, the origin of animals may not have been triggered by a contemporaneous rise in the oxygen content...

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

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......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...

Petrogenesis and geodynamic implications of Ediacaran highly fractionated A-type granitoids in the north Arabian-Nubian Shield (Egypt): Constraints from whole-rock geochemistry and Sr-Nd isotopes

Science.gov (United States)

Sami, Mabrouk; Ntaflos, Theodoros; Farahat, Esam S.; Mohamed, Haroun A.; Hauzenberger, Christoph; Ahmed, Awaad F.

2018-04-01

Mineral chemistry, whole-rock geochemical and Sr-Nd isotopic data are reported for the Abu-Diab granitoids in the northern Arabian-Nubian Shield (ANS) of Egypt, to investigate their petrogenesis and geodynamic significance. Gabal Abu-Diab constitute a multiphase pluton, consisting largely of two-mica granites (TMGs) enclosing microgranular enclaves and intruded by garnet bearing muscovite granites (GMGs) and muscovite granites (MGs). The granitoids are weakly peraluminous (A/CNK = 1.01-1.12) and show high SiO2 (>72.9 wt%) and alkali (K2O + Na2O = 8.60-9.13) contents. The geochemical features show that they are post-collisional and highly fractionated A-type granitoids. Compared to their host TMGs, the microgranular enclaves are strongly peraluminous (A/CNK = 1.18-1.24) with lower SiO2 and higher abundances of trace elements. The TMGs are depleted in Ba, Nb, P and Ti and are enriched in LREEs relative to HREEs with weakly negative Eu anomalies (Eu/Eu* = 0.45-0.64). In contrast, the GMGs and MGs are extremely depleted in Ba, Sr and Ti and have tetrad-type REE patterns (TE1-3 = 1.1-1.3) with strongly pronounced negative Eu anomalies (Eu/Eu* = 0.03-0.26), similar to rare metals bearing granites. The Ediacaran (585 ± 24 Ma) TMGs, are characterized by restricted and relatively low initial 87Sr/86Sr ratios (0.70337-0.70382) that suggests their derivation from a depleted mantle source, with little contamination from the older continental crust. In contrast, the GMGs and MGs have extremely high 87Rb/86Sr and 87Sr/86Sr ratios that reflect the disturbance of the Rb-Sr isotopic system and may give an indication for magmatic-fluid interaction. However, all the granitoids display positive εNd(t) (4.41-6.57) and depleted mantle model ages TDM2 between 777 and 956 Ma, which indicate their derivation from a Neoproterozoic juvenile magma sources and preclude the occurrence of pre-Neoproterozoic crustal rocks in the ANS. The microgranular enclaves represent globules of hot mafic

Formate Formation and Formate Conversion in Biological Fuels Production

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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.

Galaxy formation

International Nuclear Information System (INIS)

Silk, J.; Di Cintio, A.; Dvorkin, I.

2014-01-01

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.

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

Satellite formation flying relative dynamics, formation design, fuel optimal maneuvers and formation maintenance

CERN Document Server

Wang, Danwei; Poh, Eng Kee

2017-01-01

This book systematically describes the concepts and principles for multi-satellite relative motion, passive and near passive formation designs, trajectory planning and control for fuel optimal formation maneuvers, and formation flying maintenance control design. As such, it provides a sound foundation for researchers and engineers in this field to develop further theories and pursue their implementations. Though satellite formation flying is widely considered to be a major advance in space technology, there are few systematic treatments of the topic in the literature. Addressing that gap, the book offers a valuable resource for academics, researchers, postgraduate students and practitioners in the field of satellite science and engineering.

Comprehensive geobiological characterization of a bituminous carbonate facies with Ediacara-type fossils (Shibantan Member, South China)

Science.gov (United States)

Duda, Jan-Peter; Blumenberg, Martin; Thiel, Volker; Simon, Klaus; Zhu, Maoyan; Reitner, Joachim

2015-04-01

The Shibantan Member (Dengying Formation, Ediacaran Period) is one of only few carbonate settings with Ediacara-type fossils worldwide (e.g. Ding & Chen, 1981; Sun, 1986; Xiao et al., 2005; Shen et al., 2009; Chen et al., 2014). However, only little is known about the sedimentology and biogeochemistry of the environments in which these organisms throve. Here we provide a comprehensive geobiological characterization of the Shibantan Member, addressing the interplay between sedimentary and (bio-) geochemical processes. Sedimentary analysis revealed that black laminated limestones of the lower Shibantan Member were deposited after a sudden local deepening in a subtidal lower- to middle ramp environment close to the storm wave base, while the dark wavy dolomites of the upper Shibantan Member were deposited in a subtidal middle ramp environment between storm- and fair weather wave base. Sedimentation in the Shibantan basin was generally highly dynamic as evidenced by a distinct slumping horizon and mass-flow deposits that were possibly due to synsedimentary tectonic processes. The microbial-mat associated biota including Ediacara-type fossils is restricted to the lower Shibantan Member. Sedimentary analysis of this part reveals a close relationship between autochthonous mat growth and allochthonous and/or para-autochthonous event deposition. During deposition of the lower Shibantan Member the water column was probably temporarily stratified, with a sub- to anoxic water layer (evidenced by Ni/Co-, V/(V+Ni) and V/Sc ratios) overlain by a oxygenated upper layer (evidenced by negative Ce anomalies and low V/Cr ratios). However, such stratification was not permanent, as mixing by storm events is evidenced by hummocky cross stratification structures. 13C-enrichments in carbonates of the Lower Shibantan Member (δ13C = +3.3 to +4.0o VPDB) together with 13C-depletions of syngenetic n-alkanes cleaved from the respective extraction residue using catalytic hydropyrolysis (HyPy; �

Why adult formation

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Andrej Justinek

1997-01-01

Full Text Available The article argues that the primary aim of adult formation is comprehensive personality development which is supposed to ensure quality existence in modern world. The article also suggests that formarion is a permanent process. Justinek puts special emphasis on adult formation methodology and defines fundamental formation styles which encourage independent action in individuals. Justinek differentiates between formation and education. methods and concludes that formation methods are related to the emotional sphere of personality, and education methods mostly to the rational. Justinek believes that formation of adults is based primarily on appropriate formation methodology.

Neoproterozoic tectonic evolution of the Jebel Saghro and Bou Azzer - El Graara inliers, eastern and central Anti-Atlas, Morocco

Science.gov (United States)

Walsh, Gregory J.; Aleinikoff, John N.; Harrison, Richard W.; Burton, William C.; Quick, James E.; Benziane, Foudad; Yazidi, Abdelaziz; Saadane, Abderrahim

2012-01-01

New mapping, geochemistry, and 17 U–Pb SHRIMP zircon ages from rocks of the Sirwa, Bou Azzer–El Graara, and Jebel Saghro inliers constrain the Neoproterozoic evolution of the eastern Anti-Atlas during Pan-African orogenesis. In the Sirwa inlier, Tonian quartzite from the pre Pan-African passive margin deposits of the Mimount Formation contains detrital zircon derived entirely from the West African Craton (WAC), with most grains yielding Eburnean Paleoproterozoic ages of about 2050 Ma. Cryogenian Pan-African orogenic activity (PA1) from about 760 to 660 Ma included northward-dipping subduction to produce a volcanic arc, followed by ophiolite obduction onto the WAC. In the Bou Azzer–El Graara inlier, calc-alkaline granodiorite and quartz diorite, dated at 650–646 Ma, are syn- to post-tectonic with respect to the second period of Pan-African orogenesis (PA2), arc-continent accretion, and related greenschist facies metamorphism. Slab break-off and lithospheric delimination may have provided the source for the supra-subduction calc-alkaline plutons. At about 646 Ma, quartz diorite intruded the Tiddiline formation placing an upper limit on molassic deposition. Widespread Ediacaran high-K calc-alkaline to shoshonitic plutonism and volcanism during the final stage of Pan-African orogenesis (PA3) occurred in a setting related to either modification of the margin of the WAC or formation of a continental volcanic arc above a short-lived southward-dipping subduction zone. In the Saghro inlier, eight plutonic rocks yield ages ranging from about 588 to 556 Ma. Sampled plutonic rocks previously considered to be Cryogenian yielded Ediacaran ages. Peraluminous rhyolitic volcanic rocks in the lower part of the Ouarzazate Supergroup, including ash-flow tuffs of the Oued Dar’a caldera, yield ages between about 574 and 571 Ma. The Oued Dar’a caldera developed in a pull-apart graben produced by a left-step in a northeast-trending, left-lateral strike-slip fault zone, and

Formation Design Strategy for SCOPE High-Elliptic Formation Flying Mission

Science.gov (United States)

Tsuda, Yuichi

2007-01-01

The new formation design strategy using simulated annealing (SA) optimization is presented. The SA algorithm is useful to survey a whole solution space of optimum formation, taking into account realistic constraints composed of continuous and discrete functions. It is revealed that this method is not only applicable for circular orbit, but also for high-elliptic orbit formation flying. The developed algorithm is first tested with a simple cart-wheel motion example, and then applied to the formation design for SCOPE. SCOPE is the next generation geomagnetotail observation mission planned in JAXA, utilizing a formation flying techonology in a high elliptic orbit. A distinctive and useful heuristics is found by investigating SA results, showing the effectiveness of the proposed design process.

Supracrustal suite of the Precambrian crystalline crust in the Ghor Province of Central Afghanistan

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Gediminas Motuza

2017-01-01

Full Text Available The Proterozoic pre-Ediacaran metamorphic basement of the southern Tajik (North Afghanistan continental block and the adjacent Band-e-Bayan zone is exposed in the Ghor Province of Central Afghanistan. It is predominantly composed of the EW-striking supracrustal succession consisting of interbedded felsic schists and gneisses (metapsammites, amphibolites (metabasalts, calcite and dolomite marbles. The metamorphic facies changes from greenschist in the Band-e-Bayan zone to amphibolite facies in the Tajik block. The supracrustal rocks of the Band-e-Bayan zone and Tajik block possess common features suggesting that the former represents a tectonized part of the latter. The geochemical characteristics of metapsammites indicate derivation of the clastic material from a continental arc and, partly from a passive continental margin, whereas the composition of metabasalts suggests their possible formation in a continental rift basin. The tectonic setting of supracrustal unit could be interpreted as a back-arc type basin. We presume that the Tajik microcontinent split off the Gondwana supercontinent along an ancient rift zone during the late Paleozoic.

Molybdenum speciation and burial pathway in weakly sulfidic environments: Insights from XAFS

Science.gov (United States)

Wagner, Meghan; Chappaz, Anthony; Lyons, Timothy W.

2017-06-01

Sedimentary molybdenum (Mo) accumulation is a robust proxy for sulfidic conditions in both modern and ancient aquatic systems and has been used to infer changing marine redox chemistry throughout Earth's history. Accurate interpretation of any proxy requires a comprehensive understanding of its biogeochemical cycling, but knowledge gaps remain concerning the geochemical mechanism(s) leading to Mo burial in anoxic sediments. Better characterization of Mo speciation should provide mechanistic insight into sedimentary Mo accumulation, and therefore in this study we investigate Mo speciation from both modern (Castle Lake, USA) and ancient (Doushantuo Formation, China) environments using X-ray Absorption Near Edge Structure (XANES) spectroscopy. By utilizing a series of laboratory-synthesized oxythiomolybdate complexes-many containing organic ligands-we expand the number of available standards to encompass a greater range of known Mo chemistry and test the linkage between Mo and total organic carbon (TOC). In weakly euxinic systems ([H2S(aq)] < 11 μM), or where sulfide is restricted to pore waters, natural samples are best represented by a linear combination of MoO3, MoOxS4-x2- (intermediate thiomolybdates), and [MoOx(cat)4-x]2- (cat = catechol, x = 2 or 3). These results suggest a revised model for how Mo accumulates in weakly sulfidic sediments, including a previously unrecognized role for organic matter in early sequestration of Mo and a de-emphasized importance for MoS42- (tetrathiomolybdate).

Molybdenum speciation and burial pathway in weakly sulfidic environments: Insights from XAFS

Energy Technology Data Exchange (ETDEWEB)

Wagner, Meghan; Chappaz, Anthony; Lyons, Timothy W.

2017-06-01

Sedimentary molybdenum (Mo) accumulation is a robust proxy for sulfidic conditions in both modern and ancient aquatic systems and has been used to infer changing marine redox chemistry throughout Earth’s history. Accurate interpretation of any proxy requires a comprehensive understanding of its biogeochemical cycling, but knowledge gaps remain concerning the geochemical mechanism(s) leading to Mo burial in anoxic sediments. Better characterization of Mo speciation should provide mechanistic insight into sedimentary Mo accumulation, and therefore in this study we investigate Mo speciation from both modern (Castle Lake, USA) and ancient (Doushantuo Formation, China) environments using X-ray Absorption Near Edge Structure (XANES) spectroscopy. By utilizing a series of laboratory-synthesized oxythiomolybdate complexes—many containing organic ligands—we expand the number of available standards to encompass a greater range of known Mo chemistry and test the linkage between Mo and total organic carbon (TOC). In weakly euxinic systems ([H2S(aq)] < 11 µM), or where sulfide is restricted to pore waters, natural samples are best represented by a linear combination of MoO3, MoOxS4-x2- (intermediate thiomolybdates), and [MoOx(cat)4-x]2- (cat = catechol, x = 2 or 3). These results suggest a revised model for how Mo accumulates in weakly sulfidic sediments, including a previously unrecognized role for organic matter in early sequestration of Mo and a de-emphasized importance for MoS42- (tetrathiomolybdate).

Rates of star formation

International Nuclear Information System (INIS)

Larson, R.B.

1977-01-01

It is illustrated that a theoretical understanding of the formation and evolution of galaxies depends on an understanding of star formation, and especially of the factors influencing the rate of star formation. Some of the theoretical problems of star formation in galaxies, some approaches that have been considered in models of galaxy evolution, and some possible observational tests that may help to clarify which processes or models are most relevant are reviewed. The material is presented under the following headings: power-law models for star formation, star formation processes (conditions required, ways of achieving these conditions), observational indications and tests, and measures of star formation rates in galaxies. 49 references

Exploring Opponent Formats

DEFF Research Database (Denmark)

Jensen, Mads Møller; Rasmussen, Majken; Grønbæk, Kaj

2013-01-01

of how the opponent format and relationships impact a game are almost absent in current research. Thus, this paper aims to elucidate how the perception of a competition differs, depending on the opponent format, by presenting a game mechanic framework. The paper furthermore presents an interactive...... football-training platform, as well as games designed to explore the different opponent formats. The games are qualitatively evaluated to illuminate the qualities of and distinctions between different types of opponent formats, proposed by the framework terminology....

ENDF/B format

International Nuclear Information System (INIS)

Khalil, M.A.; Lemmel, H.D.

1986-09-01

This document is a brief user's description of the format of ENDF/B. This format, originally designed for the US Evaluated Nuclear Data File, is recommended for international use. This summary is an aid to customers of the IAEA Nuclear Data Section when receiving data retrievals in ENDF/B format. For more detailed information the report BNL-NCS-50496 (ENDF 102) should be consulted. An Appendix to the present document gives a summary of the format differences between ENDF/B-4 and ENDF/B-5. (author)

The Gas-Phase Formation of Methyl Formate in Hot Molecular Cores

Science.gov (United States)

Horn, Anne; Møllendal, Harald; Sekiguchi, Osamu; Uggerud, Einar; Roberts, Helen; Herbst, Eric; Viggiano, A. A.; Fridgen, Travis D.

2004-08-01

Methyl formate, HCOOCH3, is a well-known interstellar molecule prominent in the spectra of hot molecular cores. The current view of its formation is that it occurs in the gas phase from precursor methanol, which is synthesized on the surfaces of grain mantles during a previous colder era and evaporates while temperatures increase during the process of high-mass star formation. The specific reaction sequence thought to form methyl formate, the ion-molecule reaction between protonated methanol and formaldehyde followed by dissociative recombination of the protonated ion [HCO(H)OCH3]+, has not been studied in detail in the laboratory. We present here the results of both a quantum chemical study of the ion-molecule reaction between [CH3OH2]+ and H2CO as well as new experimental work on the system. In addition, we report theoretical and experimental studies for a variety of other possible gas-phase reactions leading to ion precursors of methyl formate. The studied chemical processes leading to methyl formate are included in a chemical model of hot cores. Our results show that none of these gas-phase processes produces enough methyl formate to explain its observed abundance.

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

Neoproterozoic–Cambrian stratigraphic framework of the Anti-Atlas and Ouzellagh promontory (High Atlas), Morocco

Science.gov (United States)

Alvaro, Jose Javier; Benziane, Fouad; Thomas, Robert; Walsh, Gregory J.; Yazidi, Abdelaziz

2014-01-01

In the last two decades, great progress has been made in the geochronological, chrono- and chemostratigraphic control of the Neoproterozoic and Cambrian from the Anti-Atlas Ranges and the Ouzellagh promontory (High Atlas). As a result, the Neoproterozoic is lithostratigraphically subdivided into: (i) the Lkest-Taghdout Group (broadly interpreted at c. 800–690 Ma) representative of rift-to-passive margin conditions on the northern West African craton; (ii) the Iriri (c. 760–740 Ma), Bou Azzer (c. 762–697 Ma) and Saghro (c. 760?–610 Ma) groups, the overlying Anezi, Bou Salda, Dadès and Tiddiline formations localized in fault-grabens, and the Ouarzazate Supergroup (c. 615–548 Ma), which form a succession of volcanosedimentary complexes recording the onset of the Pan-African orogeny and its aftermath; and (iii) the Taroudant (the Ediacaran–Cambrian boundary lying in the Tifnout Member of the Adoudou Formation), Tata, Feijas Internes and Tabanite groups that have recorded development of the late Ediacaran–Cambrian Atlas Rift. Recent discussions of Moroccan strata to select new global GSSPs by the International Subcommissions on Ediacaran and Cambrian Stratigraphy have raised the stratigraphic interest in this region. A revised and updated stratigraphic framework is proposed here to assist the tasks of both subcommissions and to fuel future discussions focused on different geological aspects of the Neoproterozoic–Cambrian time span.

Digital Forensics Formats: Seeking a Digital Preservation Storage Container Format for Web Archiving

Directory of Open Access Journals (Sweden)

Yunhyong Kim

2012-12-01

Full Text Available In this paper we discuss archival storage container formats from the point of view of digital curation and preservation, an aspect of preservation overlooked by most other studies. Considering established approaches to data management as our jumping off point, we selected seven container format attributes that are core to the long term accessibility of digital materials. We have labeled these core preservation attributes. These attributes are then used as evaluation criteria to compare storage container formats belonging to five common categories: formats for archiving selected content (e.g. tar, WARC, disk image formats that capture data for recovery or installation (partimage, dd raw image, these two types combined with a selected compression algorithm (e.g. tar+gzip, formats that combine packing and compression (e.g. 7-zip, and forensic file formats for data analysis in criminal investigations (e.g. aff – Advanced Forensic File format. We present a general discussion of the storage container format landscape in terms of the attributes we discuss, and make a direct comparison between the three most promising archival formats: tar, WARC, and aff. We conclude by suggesting the next steps to take the research forward and to validate the observations we have made.

Late Mesoproterozoic to Early Paleozoic history of metamorphic basement from the southeastern Chiapas Massif Complex, Mexico, and implications for the evolution of NW Gondwana

Science.gov (United States)

Weber, Bodo; González-Guzmán, Reneé; Manjarrez-Juárez, Román; Cisneros de León, Alejandro; Martens, Uwe; Solari, Luigi; Hecht, Lutz; Valencia, Victor

2018-02-01

In this paper, U-Pb zircon geochronology, Lu-Hf and Sm-Nd isotope systematics, geochemistry and geothermobarometry of metaigneous basement rocks exposed in the southeastern Chiapas Massif Complex are presented. Geologic mapping of the newly defined "El Triunfo Complex" located at the southeastern edge of the Chiapas Massif reveals (1) partial melting of a metamorphic basement mainly constituted by mafic metaigneous rocks (Candelaria unit), (2) an Ediacaran metasedimentary sequence (Jocote unit), and (3) occurrence of massif-type anorthosite. All these units are intruded by undeformed Ordovician plutonic rocks of the Motozintla suite. Pressure and temperature estimates using Ca-amphiboles, plagioclase and phengite revealed prograde metamorphism that reached peak conditions at 650 °C and 6 kbar, sufficient for partial melting under water saturated conditions. Relict rutile in titanite and clinopyroxene in amphibolite further indicate a previous metamorphic event at higher P-T conditions. U-Pb zircon ages from felsic orthogneiss boudins hosted in deformed amphibolite and migmatite yield crystallization ages of 1.0 Ga, indicating that dry granitic protoliths represent remnants of Rodinia-type basement. Additionally, a mid-Tonian ( 920 Ma) metamorphic overprint is suggested by recrystallized zircon from a banded gneiss. Zircon from folded amphibolite samples yield mainly Ordovician ages ranging from 457 to 444 Ma that are indistinguishable from the age of the undeformed Motozintla plutonic suite. Similar ages between igneous- and metamorphic- zircon suggest a coeval formation during a high-grade metamorphic event, in which textural discrepancies are explained in terms of differing zircon formation mechanisms such as sub-solidus recrystallization and precipitation from anatectic melts. In addition, some amphibolite samples contain inherited zircon yielding Stenian-Tonian ages around 1.0 Ga. Lu-Hf and Sm-Nd isotopes and geochemical data indicate that the protoliths of

Connecting the Cosmic Star Formation Rate with the Local Star Formation

Science.gov (United States)

Gribel, Carolina; Miranda, Oswaldo D.; Williams Vilas-Boas, José

2017-11-01

We present a model that unifies the cosmic star formation rate (CSFR), obtained through the hierarchical structure formation scenario, with the (Galactic) local star formation rate (SFR). It is possible to use the SFR to generate a CSFR mapping through the density probability distribution functions commonly used to study the role of turbulence in the star-forming regions of the Galaxy. We obtain a consistent mapping from redshift z˜ 20 up to the present (z = 0). Our results show that the turbulence exhibits a dual character, providing high values for the star formation efficiency ( ˜ 0.32) in the redshift interval z˜ 3.5{--}20 and reducing its value to =0.021 at z = 0. The value of the Mach number ({{ M }}{crit}), from which rapidly decreases, is dependent on both the polytropic index (Γ) and the minimum density contrast of the gas. We also derive Larson’s first law associated with the velocity dispersion ( ) in the local star formation regions. Our model shows good agreement with Larson’s law in the ˜ 10{--}50 {pc} range, providing typical temperatures {T}0˜ 10{--}80 {{K}} for the gas associated with star formation. As a consequence, dark matter halos of great mass could contain a number of halos of much smaller mass, and be able to form structures similar to globular clusters. Thus, Larson’s law emerges as a result of the very formation of large-scale structures, which in turn would allow the formation of galactic systems, including our Galaxy.

Formative assessment : Enriching teaching and learning with formative assesment

NARCIS (Netherlands)

van Diggelen, M.R.; Morgan, C.M.; Funk, M.; Bruns, M.

2016-01-01

Formative assessment is a valuable aspect in teaching and learning, and is proven to be an e ective learning method. There is evidence that adding formative assessment to your teaching increases students’ learning results (Black and William, 1998), but in practice many of the possibilities are left

THE SPECIAL STATUS OF EXOGENOUS WORD-FORMATION WITHIN THE GERMAN WORD-FORMATION SYSTEM

Directory of Open Access Journals (Sweden)

Zhilyuk Sergey Aleksandrovich

2014-06-01

Full Text Available The article presents the properties of exogenous word-formation system taking into account the existence of two word-formation systems in modern German. On the basis of foreign research which reveal modern trends in German word-formation connected with the internationalization and the development of new European Latin language. The author defines key features of exogenous word-formation, i.e. foreign origin of wordformation units, unmotivated units, unmotivated interchange in base and affixes as well as limited distribution rules in combination with German word-formation. The article analyzes various approaches to word-division, as well as motivated and unmotivated interchange of consonants in bases and in affixes. Unmotivated interchange showcases a special status of the exogenous word-formation within German. Another item covered by the article is the issue of confix. The article has opinions of researchers about correctness of its separation and a list of its features. The author presents his definition of confix: a confix is a bound exogenous word-formation unit with a certain lexical and semantic meaning and joining other units directly or indirectly (through linking morpheme -o-, which is able to make a base. Moreover, some confixes are able to participate at word-combination and have unlimited distribution. So far, confix showcases the integration of exogenous word-formation and traditional German word-formation. The research proves the special status of exogenous word-formation in German. Its results can be used as a base for further analysis of co-existing word-formation systems in German and determination of their characteristic features.

Comet formation

Science.gov (United States)

Blum, J.

2014-07-01

There has been vast progress in our understanding of planetesimal formation over the past decades, owing to a number of laboratory experiments as well as to refined models of dust and ice agglomeration in protoplanetary disks. Coagulation rapidly forms cm-sized ''pebbles'' by direct sticking in collisions at low velocities (Güttler et al. 2010; Zsom et al. 2010). For the further growth, two model approaches are currently being discussed: (1) Local concentration of pebbles in nebular instabilities until gravitational instability occurs (Johansen et al. 2007). (2) A competition between fragmentation and mass transfer in collisions among the dusty bodies, in which a few ''lucky winners'' make it to planetesimal sizes (Windmark et al. 2012a,b; Garaud et al. 2013). Predictions of the physical properties of the resulting bodies in both models allow a distinction of the two formation scenarios of planetesimals. In particular, the tensile strength (i.e, the inner cohesion) of the planetesimals differ widely between the two models (Skorov & Blum 2012; Blum et al. 2014). While model (1) predicts tensile strengths on the order of ˜ 1 Pa, model (2) results in rather compactified dusty bodies with tensile strengths in the kPa regime. If comets are km-sized survivors of the planetesimal-formation era, they should in principle hold the secret of their formation process. Water ice is the prime volatile responsible for the activity of comets. Thermophysical models of the heat and mass transport close to the comet-nucleus surface predict water-ice sublimation temperatures that relate to maximum sublimation pressures well below the kPa regime predicted for formation scenario (2). Model (1), however, is in agreement with the observed dust and gas activity of comets. Thus, a formation scenario for cometesimals involving gravitational instability is favored (Blum et al. 2014).

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...... an overview of cement production, selected cement properties, and clinker phase relations. An extended summary of laboratory-scale investigations on clinkerization reactions, the most important reactions in cement production, is provided. Clinker formations by solid state reactions, solid−liquid and liquid......−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....

Theory of aurora formation

International Nuclear Information System (INIS)

Hasegawa, Akira.

1975-04-01

A new theory of aurora formation is presented based on Alfven wave-electron interaction. The theory explains consistently 1) the electron acceleration process, 2) the formation of auroral layers and 3) the long wave formation in the longitudinal direction. (auth.)

Toward a unifying model for the late Neoproterozoic sulfur cycle

Science.gov (United States)

Johnston, D. T.; Gill, B. C.; Ries, J. B.; OBrien, T.; Macdonald, F. A.

2011-12-01

The latest Proterozoic has always fascinated Earth historians. Between the long identified enigmas surrounding the sudden appearance of animals and the more recent infatuation with large-sale geochemical anomalies (i.e. the Shuram - Wonaka event), the closing 90 million years of the Proterozoic - the Ediacaran - houses a number of important and unanswered questions. Detailed redox geochemistry and stable isotope reconstructions of stratigraphic units covering this time interval have begun to unravel some of it's mysteries, however much remains to be explained. The sulfur cycle, with it's intimate links to both the marine carbon cycle (through remineralization reactions) and overall oxidant budgets (via seawater sulfate), sits poised to provide a sharp tool to track environmental change. Previous work has recognized this potential, and serves as a point of entrance for our current work. However what is lacking - and the goal of this study - is to place quantitative constraints the geochemical evolution of marine basins through this interval. Here we will present multiple sulfur isotope data from pyrite and sulfates through Ediacaran stratigraphy from the Yukon, Russia and Namibia. To maximize the utility of sulfur isotope studies, we have focused on Ediacaran stratigraphic sections from multiple continents that record both the Shuram anomaly and contain rich fossil records. These sections provide, when interpreted together, a fresh opportunity to revisit the geochemical setting that gave rise to animals. Importantly, the inclusion of multiple sulfur isotope data allows us to place further constraints on the mechanisms underpinning isotopic variability. For instance, when coupled with new experimental data, tighter constraints are provided on how fractionation scales with sulfate concentrations. This may allow for decoupling changes in biological fractionations from modifications to the global sulfur cycle (i.e. changes in seawater sulfate concentrations or the vigor

THE SPECIAL STATUS OF EXOGENOUS WORD-FORMATION WITHIN THE GERMAN WORD-FORMATION SYSTEM

OpenAIRE

Zhilyuk Sergey Aleksandrovich

2014-01-01

The article presents the properties of exogenous word-formation system taking into account the existence of two word-formation systems in modern German. On the basis of foreign research which reveal modern trends in German word-formation connected with the internationalization and the development of new European Latin language. The author defines key features of exogenous word-formation, i.e. foreign origin of wordformation units, unmotivated units, unmotivated interchange in base and affixes...

Star formation

International Nuclear Information System (INIS)

Woodward, P.R.

1978-01-01

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

The advent of animals: The view from the Ediacaran

Science.gov (United States)

Droser, Mary L.; Gehling, James G.

2015-04-01

Patterns of origination and evolution of early complex life on this planet are largely interpreted from the fossils of the Precambrian soft-bodied Ediacara Biota. These fossils occur globally and represent a diverse suite of organisms living in marine environments. Although these exceptionally preserved fossil assemblages are typically difficult to reconcile with modern phyla, examination of the morphology, ecology, and taphonomy of these taxa provides keys to their relationships with modern taxa. Within the more than 30 million y range of the Ediacara Biota, fossils of these multicellular organisms demonstrate the advent of mobility, heterotrophy by multicellular animals, skeletonization, sexual reproduction, and the assembly of complex ecosystems, all of which are attributes of modern animals. This approach to these fossils, without the constraint of attempting phylogenetic reconstructions, provides a mechanism for comparing these taxa with both living and extinct animals.

Vascular lumen formation.

Science.gov (United States)

Lammert, Eckhard; Axnick, Jennifer

2012-04-01

The vascular system developed early in evolution. It is required in large multicellular organisms for the transport of nutrients, oxygen, and waste products to and from tissues. The vascular system is composed of hollow tubes, which have a high level of complexity in vertebrates. Vasculogenesis describes the de novo formation of blood vessels, e.g., aorta formation in vertebrate embryogenesis. In contrast, angiogenesis is the formation of blood vessels from preexisting ones, e.g., sprouting of intersomitic blood vessels from the aorta. Importantly, the lumen of all blood vessels in vertebrates is lined and formed by endothelial cells. In both vasculogenesis and angiogenesis, lumen formation takes place in a cord of endothelial cells. It involves a complex molecular mechanism composed of endothelial cell repulsion at the cell-cell contacts within the endothelial cell cords, junctional rearrangement, and endothelial cell shape change. As the vascular system also participates in the course of many diseases, such as cancer, stroke, and myocardial infarction, it is important to understand and make use of the molecular mechanisms of blood vessel formation to better understand and manipulate the pathomechanisms involved.

Isothermal Martensite Formation

DEFF Research Database (Denmark)

Villa, Matteo

Isothermal (i.e. time dependent) martensite formation in steel was first observed in the 40ies of the XXth century and is still treated as an anomaly in the description of martensite formation which is considered as a-thermal (i.e. independent of time). Recently, the clarification of the mechanism...... of lattice strains provided fundamental information on the state of stress in the material and clarified the role of the strain energy on martensite formation. Electron backscatter diffraction revealed that the microstructure of the material and the morphology of martensite were independent on the cooling...... leading to isothermal kinetics acquired new practical relevance because of the identification of isothermal martensite formation as the most likely process responsible for enhanced performances of sub-zero Celsius treated high carbon steel products. In the present work, different iron based alloys...

Data format translation routines

International Nuclear Information System (INIS)

Burris, R.D.

1981-02-01

To enable the effective connection of several dissimilar computers into a network, modification of the data being passed from one computer to another may become necessary. This document describes a package of routines which permit the translation of data in PDP-8 formats to PDP-11 or DECsystem-10 formats or from PDP-11 format to DECsystem-10 format. Additional routines are described which permit the effective use of the translation routines in the environment of the Fusion Energy Division (FED) network and the Elmo Bumpy Torus (EBT) data base

From Sermon Formation to Preacher Formation

DEFF Research Database (Denmark)

Gaarden, Marianne

2016-01-01

today is less about exercising the authority of an office and more about embodying authenticity. I argue that traditional homiletic education can benefit from implementing a learner-centered approach to teaching moving from sermon formation towards preacher formation, in order to develop and train...... preachers. This involves a learning strategy to ministry where theological skills, pastoral competences, and own personality are interwoven. Teaching here means facilitating a room of learning where teacher’s power and control is reduced, allowing the preacher to reflect upon own practice without being...... judged, evaluated, or critiqued. In this paper, I explain how a learner-centered approach to education works in practice and show how pastors experience the teaching method and the congregations’ positive response to their improvements. I shall present the results of a focus-group interview with pastors...

Molybdenum speciation and burial pathway in weakly sulfidic environments: Insights from XAFS

Energy Technology Data Exchange (ETDEWEB)

Wagner, Meghan; Chappaz, Anthony; Lyons, Timothy W.

2017-06-01

Sedimentary molybdenum (Mo) accumulation is a robust proxy for sulfidic conditions in both modern and ancient aquatic systems and has been used to infer changing marine redox chemistry throughout Earth’s history. Accurate interpretation of any proxy requires a comprehensive understanding of its biogeochemical cycling, but knowledge gaps remain concerning the geochemical mechanism(s) leading to Mo burial in anoxic sediments. Better characterization of Mo speciation should provide mechanistic insight into sedimentary Mo accumulation, and therefore in this study we investigate Mo speciation from both modern (Castle Lake, USA) and ancient (Doushantuo Formation, China) environments using X-ray Absorption Near Edge Structure (XANES) spectroscopy. By utilizing a series of laboratory-synthesized oxythiomolybdate complexes—many containing organic ligands—we expand the number of available standards to encompass a greater range of known Mo chemistry and test the linkage between Mo and total organic carbon (TOC). In weakly euxinic systems ([H₂S_(aq)] < 11 µM), or where sulfide is restricted to pore waters, natural samples are best represented by a linear combination of MoO₃, MoO_xS_4-x^2- (intermediate thiomolybdates), and [MoO_x(cat)_4-x]^2- (cat = catechol, x = 2 or 3). These results suggest a revised model for how Mo accumulates in weakly sulfidic sediments, including a previously unrecognized role for organic matter in early sequestration of Mo and a de-emphasized importance for MoS₄^2- (tetrathiomolybdate).

Feedback in formative OSCEs: comparison between direct observation and video-based formats

Science.gov (United States)

Junod Perron, Noëlle; Louis-Simonet, Martine; Cerutti, Bernard; Pfarrwaller, Eva; Sommer, Johanna; Nendaz, Mathieu

2016-01-01

Introduction Medical students at the Faculty of Medicine, University of Geneva, Switzerland, have the opportunity to practice clinical skills with simulated patients during formative sessions in preparation for clerkships. These sessions are given in two formats: 1) direct observation of an encounter followed by verbal feedback (direct feedback) and 2) subsequent review of the videotaped encounter by both student and supervisor (video-based feedback). The aim of the study was to evaluate whether content and process of feedback differed between both formats. Methods In 2013, all second- and third-year medical students and clinical supervisors involved in formative sessions were asked to take part in the study. A sample of audiotaped feedback sessions involving supervisors who gave feedback in both formats were analyzed (content and process of the feedback) using a 21-item feedback scale. Results Forty-eight audiotaped feedback sessions involving 12 supervisors were analyzed (2 direct and 2 video-based sessions per supervisor). When adjusted for the length of feedback, there were significant differences in terms of content and process between both formats; the number of communication skills and clinical reasoning items addressed were higher in the video-based format (11.29 vs. 7.71, p=0.002 and 3.71 vs. 2.04, p=0.010, respectively). Supervisors engaged students more actively during the video-based sessions than during direct feedback sessions (self-assessment: 4.00 vs. 3.17, p=0.007; active problem-solving: 3.92 vs. 3.42, p=0.009). Students made similar observations and tended to consider that the video feedback was more useful for improving some clinical skills. Conclusion Video-based feedback facilitates discussion of clinical reasoning, communication, and professionalism issues while at the same time actively engaging students. Different time and conceptual frameworks may explain observed differences. The choice of feedback format should depend on the educational

Feedback in formative OSCEs: comparison between direct observation and video-based formats

Directory of Open Access Journals (Sweden)

Noëlle Junod Perron

2016-11-01

Full Text Available Introduction: Medical students at the Faculty of Medicine, University of Geneva, Switzerland, have the opportunity to practice clinical skills with simulated patients during formative sessions in preparation for clerkships. These sessions are given in two formats: 1 direct observation of an encounter followed by verbal feedback (direct feedback and 2 subsequent review of the videotaped encounter by both student and supervisor (video-based feedback. The aim of the study was to evaluate whether content and process of feedback differed between both formats. Methods: In 2013, all second- and third-year medical students and clinical supervisors involved in formative sessions were asked to take part in the study. A sample of audiotaped feedback sessions involving supervisors who gave feedback in both formats were analyzed (content and process of the feedback using a 21-item feedback scale. Results: Forty-eight audiotaped feedback sessions involving 12 supervisors were analyzed (2 direct and 2 video-based sessions per supervisor. When adjusted for the length of feedback, there were significant differences in terms of content and process between both formats; the number of communication skills and clinical reasoning items addressed were higher in the video-based format (11.29 vs. 7.71, p=0.002 and 3.71 vs. 2.04, p=0.010, respectively. Supervisors engaged students more actively during the video-based sessions than during direct feedback sessions (self-assessment: 4.00 vs. 3.17, p=0.007; active problem-solving: 3.92 vs. 3.42, p=0.009. Students made similar observations and tended to consider that the video feedback was more useful for improving some clinical skills. Conclusion: Video-based feedback facilitates discussion of clinical reasoning, communication, and professionalism issues while at the same time actively engaging students. Different time and conceptual frameworks may explain observed differences. The choice of feedback format should depend on

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...... is important, since it helps constraining chemical evolution models at high redshift. A new project studying how the population of galaxies hosting GRBs relate to other galaxy population is outlined in the conclusion of this thesis. The core of this project will be to quantify how the stellar mass function...

The Brasiliano collage in South America: a review

Directory of Open Access Journals (Sweden)

Benjamim Bley de Brito Neves

Full Text Available Analysis of recent geological and geochronological data from the basement of the South American platform indicates that the Brasiliano orogenic collage took place in four distinct pulses: a Early Cryogenian (ca. 800 - 740Ma; b Late Cryogenian-Early Ediacaran (ca. 660 - 610 Ma; c Early-Middle Ediacaran (c. 590 - 560 Ma; and d Late Cambrian (520 - 500 Ma. The first three pulses are well represented in most Neoproterozoic structural provinces in West Gondwana. The youngest orogenic phase/pulse, however, is only seen in Argentina (Pampean Orogeny and Brazil, in eastern Rio de Janeiro State (Búzios Orogeny. The period between ca. 750 and 500 Ma is comparable to that reported for the amalgamation of various continental fragments in East (Arabian-Nubian, Mozambique, Kuunga and North Gondwana (Cadomian. However, important differences in the nature and ages of events are recognized, which can be expected in view of the magnitude of Gondwana agglutination and the diversity of paleogeographic and tectonic scenarios. West Gondwana shows an interesting peculiarity: lithologically and tectonically diversified Tonian terranes underlie Brasiliano orogenic buildups. They were strongly reworked during most of the orogenic pulses. The Tonian terranes (1000 - 900 Ma and their relation with Rodinia or with the processes of Gondwana fusion remains an open question. Indications of their presence in East Gondwana are still poorly documented.

Reconsidering formative measurement.

Science.gov (United States)

Howell, Roy D; Breivik, Einar; Wilcox, James B

2007-06-01

The relationship between observable responses and the latent constructs they are purported to measure has received considerable attention recently, with particular focus on what has become known as formative measurement. This alternative to reflective measurement in the area of theory-testing research is examined in the context of the potential for interpretational confounding and a construct's ability to function as a point variable within a larger model. Although these issues have been addressed in the traditional reflective measurement context, the authors suggest that they are particularly relevant in evaluating formative measurement models. On the basis of this analysis, the authors conclude that formative measurement is not an equally attractive alternative to reflective measurement and that whenever possible, in developing new measures or choosing among alternative existing measures, researchers should opt for reflective measurement. In addition, the authors provide guidelines for researchers dealing with existing formative measures. Copyright 2007 APA, all rights reserved.

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.

Stages of ores formation

International Nuclear Information System (INIS)

Khasanov, A.Kh.

1988-01-01

Deposit formation (especially endogenous) is the complicated, multi-stage and long process. Establishment of deposit formation succession, age-specific correlations of minerals and aggregates have a high importance at solving genetic questions. Studying of minerals correlations and mineral aggregates, succession of their crystallization and other observations let restore the history of deposit formation, pick up in it different on duration and physical and chemical conditions stages

Television Format As a Site of Cultural Negotiation: Studying the Structures, Agencies and Practices of Format Adaptation

NARCIS (Netherlands)

Keinonen, Heidi

2016-01-01

abstractDespite the growing number of publications on television formats, specific theorisations regarding formats and format adaptation, in particular, are still rare. In this article, I introduce a synthesizing approach for studying format appropriation. Drawing on format study, media industry

Blistering and bubble formation

International Nuclear Information System (INIS)

Roth, J.

1976-01-01

Blister formation in metals has been observed during bombardment with inert-gas ions in the energy range between 1 and 2000 keV at doses of about 10 17 to 10 19 cm -2 . The changes in surface topography and the erosion yields were mainly studied in the scanning electron microscope (SEM). Additionally the release of the implanted gas during blister formation was observed. Recently measurements on single crystals were performed determining simultaneously the implantation profile, the total amount of trapped ions, the depth distribution of the induced lattice damage and the thickness of the covers of the blisters. In several stages of the formation process of blisters the implanted layer was observed in the transmission electron microscope (TEM) showing the formation of gas bubbles. Using the results of all these measurements in this review an attempt is made to develop a model of blister formation combining the effects of hydrostatic pressure in the gas bubbles and lateral stress due to volume swelling. (author)

Fracturing formations in wells

Energy Technology Data Exchange (ETDEWEB)

Daroza, R A

1964-05-15

This well stimulation method comprises introducing through the well bore a low-penetrating, dilatant fluid, and subjecting the fluid to sufficient pressure to produce fractures in the formation. The fluid is permitted to remain in contact with the formation so as to become diluted by the formation fluids, and thereby lose its properties of dilatancy. Also, a penetrating fluid, containing a propping agent suspended therein, in introduced into contact with the fractures at a pressure substantially reduced with respect to that pressure which would have been required, prior to the fracturing operation performed using the low-penetrating dilatant fluid. The propping agent is deposited within the fractures, and thereafter, fluid production is resumed from the fractured formation. (2 claims)

'TV Format Protection through Marketing Strategies?'

OpenAIRE

Singh, Sukhpreet

2008-01-01

Commercially successful programme ideas are often imitated or adapted. Television formats, in particular, are routinely copied. Starting from radio formats in the 1950s to game shows and reality programme formats of today, producers have accused others of “stealing”. Although formats constitute one of the most important exports for British TV producers, there is still no certainty about the legal protection of TV formats from copycat versions. Since TV formats fail to fall neatly within the d...

Dislocation processes in quasicrystals-Kink-pair formation control or jog-pair formation control

International Nuclear Information System (INIS)

Takeuchi, Shin

2005-01-01

A computer simulation of dislocation in a model quasiperiodic lattice indicates that the dislocation feels a large Peierls potential when oriented in particular directions. For a dislocation with a high Peierls potential, the glide velocity and the climb velocity of the dislocation can be described almost in parallel in terms of the kink-pair formation followed by kink motion and the jog-pair formation followed by jog motion, respectively. The activation enthalpy of the kink-pair formation is the sum of the kink-pair formation enthalpy and the atomic jump activation enthalpy, while the activation enthalpy of the jog-pair formation involves the jog-pair enthalpy and the self-diffusion enthalpy. Since the kink-pair energy can be considerably larger than the jog-pair energy, the climb velocity can be faster than the glide velocity, so that the plastic deformation of quasicrystals can be brought not by dislocation glide but by dislocation climb at high temperatures

Solubility studies of oxovanadium(V) formate and vanadyl formate in aqueous medium

International Nuclear Information System (INIS)

Tripathi, V.S.; Bairwa, K.K.; Naik, D.B.; Raje, N.H.; Bera, S.

2014-01-01

The solubility of oxovanadium(V) formate and vanadyl formate in aqueous medium has been determined. These compounds are important for preparation of strong reducing V(II) compounds which are used in stainless steel based nuclear power plants for decontamination

Planet formation in Binaries

OpenAIRE

Thebault, Ph.; Haghighipour, N.

2014-01-01

Spurred by the discovery of numerous exoplanets in multiple systems, binaries have become in recent years one of the main topics in planet formation research. Numerous studies have investigated to what extent the presence of a stellar companion can affect the planet formation process. Such studies have implications that can reach beyond the sole context of binaries, as they allow to test certain aspects of the planet formation scenario by submitting them to extreme environments. We review her...

What Determines Star Formation Rates?

Science.gov (United States)

Evans, Neal John

2017-06-01

The relations between star formation and gas have received renewed attention. We combine studies on scales ranging from local (within 0.5 kpc) to distant galaxies to assess what factors contribute to star formation. These include studies of star forming regions in the Milky Way, the LMC, nearby galaxies with spatially resolved star formation, and integrated galaxy studies. We test whether total molecular gas or dense gas provides the best predictor of star formation rate. The star formation ``efficiency," defined as star formation rate divided by mass, spreads over a large range when the mass refers to molecular gas; the standard deviation of the log of the efficiency decreases by a factor of three when the mass of relatively dense molecular gas is used rather than the mass of all the molecular gas. We suggest ways to further develop the concept of "dense gas" to incorporate other factors, such as turbulence.

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 requireme......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...

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.

Radiogeochemical features of hydrothermal metasomatic formations

International Nuclear Information System (INIS)

Plyushchev, E.V.; Ryabova, L.A.; Shatov, V.V.

1978-01-01

Considered are the most general peculiarities of uranium and thorium distributions in hydrothermal-metasomatic formations of three levels of substance formation: 1) in hydrothermal minerals; 2) in natural associations of these minerals (in the altered rocks, metasomatites, ores, etc.); 3) ordened series of zonally and in stage conjugated hydrothermal-metasomatic formations. Statistically stable recurrence of natural combinations of hydrothermal-metasomatic formations points out conjugation of their formation in the directed evolution in the general hydrothermal process. Series of metasomatic formations, the initial members of which are potassium metasomatites, mostly result in accumulation up to industrial concentrations of radioactive elements in final members of these formations. Development of midlow-temperature propylitic alterations in highly radiative rocks causes the same accumulation

ENDF/B Format

International Nuclear Information System (INIS)

Khalil, M.A.

1975-01-01

This document is a brief user's description of the format of ENDF/B, the evaluated neutron nuclear data library of the US National Nuclear Data Center. This summary is an aid to customers of the IAEA Nuclear Data Section when receiving data retrievals in ENDF/B format. For more detailed information the report BNL-50274 (ENDF-102) should be consulted. (author)

Geological factors of deposit formation

International Nuclear Information System (INIS)

Grushevoj, G.V.

1980-01-01

Geologic factors of hydrogenic uranium deposit formation are considered. Structural, formation and lithological-facies factors of deposit formation, connected with zones of stratal oxidation, are characterized. Peculiarities of deposit localization, connected with orogenic structures of Mesozoic and lenozoic age, are described. It is noted that deposits of anagenous group are widely spread in Paleozoic formations, infiltration uranium deposits are localized mainly in Cenozoic sediments, while uranium mineralization both anagenous and infiltration groups are widely developed in Mesozoic sediments. Anagenous deposits were formed in non-oxygen situation, their age varies from 200 to 55 mln years. Infiltration deposit formation is determined by asymmetric oxidation zonation, their age varies from 10 - 40 mln years to dozens of thousand years [ru

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...

FORMATION CONSTANTS AND THERMODYNAMIC ...

African Journals Online (AJOL)

KEY WORDS: Metal complexes, Schiff base ligand, Formation constant, DFT calculation ... best values for the formation constants of the proposed equilibrium model by .... to its positive charge distribution and the ligand deformation geometry.

Stacked Star Formation Rate Profiles of Bursty Galaxies Exhibit “Coherent” Star Formation

Science.gov (United States)

Orr, Matthew E.; Hayward, Christopher C.; Nelson, Erica J.; Hopkins, Philip F.; Faucher-Giguère, Claude-André; Kereš, Dušan; Chan, T. K.; Schmitz, Denise M.; Miller, Tim B.

2017-11-01

In a recent work based on 3200 stacked Hα maps of galaxies at z˜ 1, Nelson et al. find evidence for “coherent star formation”: the stacked star formation rate (SFR) profiles of galaxies above (below) the “star formation main sequence” (MS) are above (below) that of galaxies on the MS at all radii. One might interpret this result as inconsistent with highly bursty star formation and evidence that galaxies evolve smoothly along the MS rather than crossing it many times. We analyze six simulated galaxies at z˜ 1 from the Feedback in Realistic Environments (FIRE) project in a manner analogous to the observations to test whether the above interpretations are correct. The trends in stacked SFR profiles are qualitatively consistent with those observed. However, SFR profiles of individual galaxies are much more complex than the stacked profiles: the former can be flat or even peak at large radii because of the highly clustered nature of star formation in the simulations. Moreover, the SFR profiles of individual galaxies above (below) the MS are not systematically above (below) those of MS galaxies at all radii. We conclude that the time-averaged coherent star formation evident stacks of observed galaxies is consistent with highly bursty, clumpy star formation of individual galaxies and is not evidence that galaxies evolve smoothly along the MS.

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.

Earth formation porosity log

International Nuclear Information System (INIS)

Smith, H.D.; Smith, M.P.; Schultz, W.E.

1977-01-01

A method for determining the porosity of earth formations in the vicinity of a cased well borehole is described, comprising the steps of: irradiating the earth formations in the vicinity of the cased well borehole with fast neutrons from a source of fast neutrons passed into the borehole; and generating a signal representative of the fast neutron population present in the well borehole at a location in the borehole, the signal is functionally related to the porosity of the earth formations in the vicinity of the borehole

Merging formation of FRC and its application to high-beta ST formation

International Nuclear Information System (INIS)

Ono, Y.; Inomoto, M.; Ueda, Y.; Matsuyama, T.; Ohshima, Y.; Katsurai, M.

2001-01-01

Merging formation of field-reversed configuration (FRC) explored not only a new scenario of highly-efficient FRC formation/amplification experiment but also a new boundary research between FRC, spheromak and spherical tokamak (ST). A new finding is that the produced FRC is transformed stably into an ultra-high-β ST by applying external toroidal field B t,ext . The toroidal field was observed to vanish around magnetic axis after the B t,ext application to the FRC, indicating formation of diamagnetic ST. The hollow current profile of FRC was maintained during the equilibrium transition, eliminating a need for the difficult hollow-current-formation process of start-up discharge of high-β ST. The energy-conversion effect of merging transformed the force-free merging spheromaks with paramagnetic current into the FRC with diamagnetic current and the further application of B t,ext did the FRC into the ultra-high-β (>60%)/diamagnetic ST, indicating the close relationship between FRC and ST in second stability. (author)

Restoring formation after leaching process

International Nuclear Information System (INIS)

Barrett, R.B.

1983-01-01

A method of restoring a formation which had uranium and other mineral values extracted by an alkaline lixiviant comprises introducing a source of phosphate in an amount sufficient to lower the level of soluble uranium compounds below that previously existing in the formation by the formation of insoluble uranium phosphate compounds

Formative Research in Educational Media.

Science.gov (United States)

Hodapp, Timothy

This paper distinguishes between basic research, applied research, and evaluation. Evaluation is broken down into two types: summative and formative. The limitations of formative research are presented, followed by a discussion of the value of the formative researcher participating in the product planning process. The types of data which formative…

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....

Tritiated ammonia formation

International Nuclear Information System (INIS)

Heung, L.K.

1995-01-01

When nitrogen was selected as the glovebox atmosphere for the Replacement Tritium Facility (RTF) at the Savannah River Site (SRS), a concern was raised as to the possibility of tritiated ammonia formation in the gloveboxes. Experimental data were produced to study the tritiated ammonia formation rate in a tritium and nitrogen mixture. A rate equation that closely simulates the experimental data was developed. This rate equation can be used to calculate the formation of tritiated ammonia from different concentrations of tritium and nitrogen. The reaction of T 2 and N 2 to form NT 3 is a slow process, particularly when the tritium concentration is low. The reaction requires weeks or months to reach radiochemical equilibrium dependent on the concentrations of the reactants. 4 refs., 6 figs., 1 tab

The NeXus data format

OpenAIRE

Könnecke, Mark; Akeroyd, Frederick A.; Osborn, Raymond; Peterson, Peter F.; Richter, Tobias; Suzuki, Jiro; Watts, Benjamin; Wintersberger, Eugen; Wuttke, Joachim; Bernstein, Herbert J.; Brewster, Aaron S.; Campbell, Stuart I.; Clausen, Björn; Cottrell, Stephen; Hoffmann, Jens Uwe

2015-01-01

NeXus is an effort by an international group of scientists to define a common data exchange and archival format for neutron, X-ray and muon experiments. NeXus is built on top of the scientific data format HDF5 and adds domain-specific rules for organizing data within HDF5 files, in addition to a dictionary of well defined domain-specific field names. The NeXus data format has two purposes. First, it defines a format that can serve as a container for all relevant data associated with a beamlin...

Inside-out Planet Formation. IV. Pebble Evolution and Planet Formation Timescales

Science.gov (United States)

Hu, Xiao; Tan, Jonathan C.; Zhu, Zhaohuan; Chatterjee, Sourav; Birnstiel, Tilman; Youdin, Andrew N.; Mohanty, Subhanjoy

2018-04-01

Systems with tightly packed inner planets (STIPs) are very common. Chatterjee & Tan proposed Inside-out Planet Formation (IOPF), an in situ formation theory, to explain these planets. IOPF involves sequential planet formation from pebble-rich rings that are fed from the outer disk and trapped at the pressure maximum associated with the dead zone inner boundary (DZIB). Planet masses are set by their ability to open a gap and cause the DZIB to retreat outwards. We present models for the disk density and temperature structures that are relevant to the conditions of IOPF. For a wide range of DZIB conditions, we evaluate the gap-opening masses of planets in these disks that are expected to lead to the truncation of pebble accretion onto the forming planet. We then consider the evolution of dust and pebbles in the disk, estimating that pebbles typically grow to sizes of a few centimeters during their radial drift from several tens of astronomical units to the inner, ≲1 au scale disk. A large fraction of the accretion flux of solids is expected to be in such pebbles. This allows us to estimate the timescales for individual planet formation and the entire planetary system formation in the IOPF scenario. We find that to produce realistic STIPs within reasonable timescales similar to disk lifetimes requires disk accretion rates of ∼10‑9 M ⊙ yr‑1 and relatively low viscosity conditions in the DZIB region, i.e., a Shakura–Sunyaev parameter of α ∼ 10‑4.

PCF File Format.

Energy Technology Data Exchange (ETDEWEB)

Thoreson, Gregory G [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

2017-08-01

PCF files are binary files designed to contain gamma spectra and neutron count rates from radiation sensors. It is the native format for the GAmma Detector Response and Analysis Software (GADRAS) package [1]. It can contain multiple spectra and information about each spectrum such as energy calibration. This document outlines the format of the file that would allow one to write a computer program to parse and write such files.

Spatially-resolved star formation histories of CALIFA galaxies. Implications for galaxy formation

Science.gov (United States)

González Delgado, R. M.; Pérez, E.; Cid Fernandes, R.; García-Benito, R.; López Fernández, R.; Vale Asari, N.; Cortijo-Ferrero, C.; de Amorim, A. L.; Lacerda, E. A. D.; Sánchez, S. F.; Lehnert, M. D.; Walcher, C. J.

2017-11-01

This paper presents the spatially resolved star formation history (SFH) of nearby galaxies with the aim of furthering our understanding of the different processes involved in the formation and evolution of galaxies. To this end, we apply the fossil record method of stellar population synthesis to a rich and diverse data set of 436 galaxies observed with integral field spectroscopy in the CALIFA survey. The sample covers a wide range of Hubble types, with stellar masses ranging from M⋆ 109 to 7 × 1011 M⊙. Spectral synthesis techniques are applied to the datacubes to retrieve the spatially resolved time evolution of the star formation rate (SFR), its intensity (ΣSFR), and other descriptors of the 2D SFH in seven bins of galaxy morphology (E, S0, Sa, Sb, Sbc, Sc, and Sd) and five bins of stellar mass. Our main results are that (a) galaxies form very fast independently of their current stellar mass, with the peak of star formation at high redshift (z > 2). Subsequent star formation is driven by M⋆ and morphology, with less massive and later type spirals showing more prolonged periods of star formation. (b) At any epoch in the past, the SFR is proportional to M⋆, with most massive galaxies having the highest absolute (but lowest specific) SFRs. (c) While today, the ΣSFR is similar for all spirals and significantly lower in early-type galaxies (ETG), in the past, the ΣSFR scales well with morphology. The central regions of today's ETGs are where the ΣSFR reached the highest values (> 103 M⊙ Gyr-1 pc-2), similar to those measured in high-redshift star-forming galaxies. (d) The evolution of ΣSFR in Sbc systems matches that of models for Milky Way-like galaxies, suggesting that the formation of a thick disk may be a common phase in spirals at early epochs. (e) The SFR and ΣSFR in outer regions of E and S0 galaxies show that they have undergone an extended phase of growth in mass between z = 2 and 0.4. The mass assembled in this phase is in agreement with

Formation of multiple networks

DEFF Research Database (Denmark)

Magnani, Matteo; Rossi, Luca

2013-01-01

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...

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.

GMC Collisions as Triggers of Star Formation. III. Density and Magnetically Regulated Star Formation

Energy Technology Data Exchange (ETDEWEB)

Wu, Benjamin [National Astronomical Observatory of Japan, Mitaka, Tokyo 181-8588 (Japan); Tan, Jonathan C. [Department of Physics, University of Florida, Gainesville, FL 32611 (United States); Christie, Duncan [Department of Astronomy, University of Florida, Gainesville, FL 32611 (United States); Nakamura, Fumitaka [National Astronomical Observatory, Mitaka, Tokyo 181-8588 (Japan); Van Loo, Sven [School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT (United Kingdom); Collins, David, E-mail: ben.wu@nao.ac.jp [Department of Physics, Florida State University, Tallahassee, FL 32306-4350 (United States)

2017-06-01

We study giant molecular cloud (GMC) collisions and their ability to trigger star cluster formation. We further develop our three-dimensional magnetized, turbulent, colliding GMC simulations by implementing star formation subgrid models. Two such models are explored: (1) “Density-Regulated,” i.e., fixed efficiency per free-fall time above a set density threshold and (2) “Magnetically Regulated,” i.e., fixed efficiency per free-fall time in regions that are magnetically supercritical. Variations of parameters associated with these models are also explored. In the non-colliding simulations, the overall level of star formation is sensitive to model parameter choices that relate to effective density thresholds. In the GMC collision simulations, the final star formation rates and efficiencies are relatively independent of these parameters. Between the non-colliding and colliding cases, we compare the morphologies of the resulting star clusters, properties of star-forming gas, time evolution of the star formation rate (SFR), spatial clustering of the stars, and resulting kinematics of the stars in comparison to the natal gas. We find that typical collisions, by creating larger amounts of dense gas, trigger earlier and enhanced star formation, resulting in 10 times higher SFRs and efficiencies. The star clusters formed from GMC collisions show greater spatial substructure and more disturbed kinematics.

A format for phylogenetic placements.

Directory of Open Access Journals (Sweden)

Frederick A Matsen

Full Text Available We have developed a unified format for phylogenetic placements, that is, mappings of environmental sequence data (e.g., short reads into a phylogenetic tree. We are motivated to do so by the growing number of tools for computing and post-processing phylogenetic placements, and the lack of an established standard for storing them. The format is lightweight, versatile, extensible, and is based on the JSON format, which can be parsed by most modern programming languages. Our format is already implemented in several tools for computing and post-processing parsimony- and likelihood-based phylogenetic placements and has worked well in practice. We believe that establishing a standard format for analyzing read placements at this early stage will lead to a more efficient development of powerful and portable post-analysis tools for the growing applications of phylogenetic placement.

Uranium logging in earth formations

International Nuclear Information System (INIS)

Givens, W.W.

1979-01-01

A technique is provided for assaying the formations surrounding a borehole for uranium. A borehole logging tool cyclically irradiates the formations with neutrons and responds to neutron fluxes produced during the period of time that prompt neutrons are being produced by the neutron fission of uranium in the formations. A borehole calibration tool employs a steady-state (continuous output) neutron source, firstly, to produce a response to neutron fluxes in models having known concentrations of uranium and, secondly, to to produce a response to neutron fluxes in the formations surrounding the borehole. The neutron flux responses of the borehole calibration tool in both the model and the formations surrounding the borehole are utilized to correct the neutron flux response of the borehole logging tool for the effects of epithermal/thermal neutron moderation, scattering, and absorption within the borehole itself

Geology, petrology and U-Pb geochronology of Serra da Rajada Granitic Pluton: implications about ediacaran magmatic evolution in NE portion of the Rio Piranhas-Serido Domain (NE of Borborema Province); Geologia, petrologia e geocronologia U-Pb do Pluton Granitico Serra da Rajada: implicacoes sobre a evolucao magmatica ediacarana na porcao do Dominio Rio Piranhas-Serido (NE da Provincia Borborema)

Energy Technology Data Exchange (ETDEWEB)

Costa, Alan Pereira da; Dantas, Alexandre Ranier, E-mail: alan.costa@cprm.gov.br, E-mail: alexandre.dantas@cprm.gov.br [Servico Geologico do Brasil (CPRM), Natal, RN (Brazil). Nucleo de Apoio de Natal/Superintendencia Regional de Recife; Nascimento, Marcos Antonio Leite do; Galindo, Antonio Carlos, E-mail: marcos@geologia.ufrn.br, E-mail: galindo@geologia.ufrn.br [Universidade Federal do Rio Grande do Norte (UFRN), Natal, RN (Brazil). Departamento de Geologia

2015-12-15

The Ediacaran plutonic activity, related to the Brazilian/Pan-African orogeny, is one of the most important geological features in the Borborema Province, formed by batholiths, stocks and dikes. The Serra da Rajada Granitic Pluton (SRGP), located in the central portion of the Rio Piranhas-Serido Domain, is an example of these bodies. This site is the target of cartographic, petrographic, lithochemical and geochronological studies. Its rocks are described as monzogranites consisting of K-feldspar, plagioclase (oligoclase-An{sub 23-24%}), quartz and biotite (main mafic), having as accessory minerals opaque, titanite, allanite, apatite and zircon. Chlorite, white mica and carbonate are alteration minerals. Lithochemical data from 15 samples show quite evolved rocks (SiO{sub 2} , 69% to 75%), rich in alkalis (Na{sub 2}O + K{sub 2}O ≥ 8.0%), depleted in MgO (≤ 0.45%), CaO (≤ 1.42%) and TiO{sub 2} (≤ 0.36%), and displaying moderate levels of Fe{sub 2}O{sub 3} t (2.16 to 3.53%). These rocks present a transitional nature between metaluminous and peraluminous (predominance of the latter) and have subalkaline/monzonitic affinity (high-K Calc-alkaline). Harker diagrams represent negative correlations in Fe{sub 2}O{sub 3}t, MgO and CaO, indicating fractionation of mafic and plagioclase. The REE spectrum show enrichment of light in relation to heavy REE (LaN/YbN = 23.70 to 10.13), with negative anomaly in Eu (Eu/ Eu* = 0.70 to 10.13) suggesting fractionation or accumulation in the feldspars source (plagioclase). Data integration allows correlating the SRGP rocks with those described as Equigranular high-K Calc-alkaline Suite. The U-Pb geochronology and Sm-Nd isotope dating indicate that the biotite monzogranite have a crystallization age of 557 ± 13 Ma and TDM model age of 2.36 Ga, respectively, and ε{sub Nd} value of - 20.10 for the crystallization age, allowing to infer a crustal source for the magma generated in the Paleoproterozoic age. (author)

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

Reflections about the mathematics teachers' formation

Directory of Open Access Journals (Sweden)

Maria José de Freitas Mendes

2010-06-01

Full Text Available This paper brings some reflections about the formation of the math teacher that made part of my marsters paper and that aimed to investigate the process of formation of the math teacher. The focus of this study incided at the contributions of teaching practice in the teacher's formation above the new paradigms of formation, as a professional development and as a reflexive teacher. These reflections, from the learning and teaching process and from the meaning of form a teacher analyse the crisis and the restructuration of the teacher's formation and conclude being necessary that in the graduation courses there's a character more practice to the pedagogical formation, making possible for the future teacher to develop attitudes of autonomy, reflexion and investigation

A possible formation scenario for dwarf spheroidal galaxies - III. Adding star formation histories to the fiducial model

Science.gov (United States)

Alarcón Jara, A. G.; Fellhauer, M.; Matus Carrillo, D. R.; Assmann, P.; Urrutia Zapata, F.; Hazeldine, J.; Aravena, C. A.

2018-02-01

Dwarf spheroidal galaxies are regarded as the basic building blocks in the formation of larger galaxies and are the most dark matter dominated systems in the Universe, known so far. There are several models that attempt to explain their formation and evolution, but they have problems modelling the formation of isolated dwarf spheroidal galaxies. Here, we will explain a possible formation scenario in which star clusters form inside the dark matter halo of a dwarf spheroidal galaxy. These star clusters suffer from low star formation efficiency and dissolve while orbiting inside the dark matter halo. Thereby, they build the faint luminous components that we observe in dwarf spheroidal galaxies. In this paper, we study this model by adding different star formation histories to the simulations and compare the results with our previous work and observational data to show that we can explain the formation of dwarf spheroidal galaxies.

Plant Formate Dehydrogenase

Energy Technology Data Exchange (ETDEWEB)

John Markwell

2005-01-10

The research in this study identified formate dehydrogenase, an enzyme that plays a metabolic role on the periphery of one-carbon metabolism, has an unusual localization in Arabidopsis thaliana and that the enzyme has an unusual kinetic plasticity. These properties make it possible that this enzyme could be engineered to attempt to engineer plants with an improved photosynthetic efficiency. We have produced transgenic Arabidopsis and tobacco plants with increased expression of the formate dehydrogenase enzyme to initiate further studies.

Formation à distance et activité du stagiaire de la formation professionnelle continue

OpenAIRE

Verquin-Savarieau, Béatrice

2014-01-01

Quels contenus des lettres de missions pour quelles démarches et activités d’ingénierie de formation, pour des étudiants salariés en activité et suivant leurs études à distance ? Cet article questionne le stage de formation professionnelle continue dans le cadre d’une formation hybride. Il s’agit d’interroger en particulier la conception de la mission de stage, en tant que contenu opératoire facilitant les transformations des sujets dans l’action. Nous présenterons le rôle crucial joué par la...

XML-based DICOM data format.

Science.gov (United States)

Yu, Cong; Yao, Zhihong

2010-04-01

To enhance the readability, improve the structure, and facilitate the sharing of digital imaging and communications in medicine (DICOM) files, this research proposed one kind of XML-based DICOM data format. Because XML Schema offers great flexibility for expressing constraints on the content model of elements, we used it to describe the new format, thus making it consistent with the one originally defined by DICOM. Meanwhile, such schemas can be used in the creation and validation of the XML-encoded DICOM files, acting as a standard for data transmission and sharing on the Web. Upon defining the new data format, we started with representing a single data element and further improved the whole data structure with the method of modularization. In contrast to the original format, the new one possesses better structure without loss of related information. In addition, we demonstrated the application of XSLT and XQuery. All of the advantages mentioned above resulted from this new data format.

Mesoarchean Banded Iron Formation sequences in Dixon Island-Cleaverville Formation, Pilbara Australia: Oxygenic signal from DXCL project

Science.gov (United States)

Kiyokawa, S.; Ito, T.; Ikehara, M.; Yamaguchi, K. E.; Naraoka, H.; Onoue, T.; Horie, K.; Sakamoto, R.; Aihara, Y.; Miki, T.

2013-12-01

The 3.2-3.1 Ga Dixon island-Cleaverville formations are well-preserved Banded Iron Formation (BIF) within hydrothermal oceanic sequence at oceanic island arc setting (Kiyokawa et al., 2002, 2006, 2012). The stratigraphy of the Dixon Island (3195+15Ma) -Cleaverville (3108+13Ma) formations shows the well preserved environmental condition at the Mesoarchean ocean floor. The stratigraphy of these formations are formed about volcano-sedimentary sequences with hydrothermal chert, black shale and banded iron formation to the top. Based on the scientific drilling of DXCL project at 2007 and 2011, detail lithology between BIF sequence was clearly understood. Four drilling holes had been done at coastal sites; the Dixon Island Formation is DX site (100m) and the Cleaverville Formation is CL2 (40m), CL1 (60m) and CL3 (200m) sites and from stratigraphic bottom to top. Coarsening and thickening upward black shale-BIF sequences are well preserved of the stratigraphy form the core samples. The Dixon Island Formation consists komatiite-rhyolite sequences with many hydrothermal veins and very fine laminated cherty rocks above them. The Cleaverville Formation contains black shale, fragments-bearing pyroclastic beds, white chert, greenish shale and BIF. The CL3 core, which drilled through BIF, shows siderite-chert beds above black shale identified before magnetite lamination bed. U-Pb SHRIMP data of the tuff in lower Dixon Island Formation is 3195+15 Ma and the pyroclastic sequence below the Cleaverville BIF is 3108+13 Ma. Sedimentation rate of these sequence is 2-8 cm/ 1000year. The hole section of the organic carbon rich black shales below BIF are similar amount of organic content and 13C isotope (around -30per mill). There are very weak sulfur MIF signal (less 0.2%) in these black shale sequence. Our result show that thick organic rich sediments may be triggered to form iron rich siderite and magnetite iron beds. The stratigraphy in this sequence quite resemble to other Iron

Observsational Planet Formation

Science.gov (United States)

Dong, Ruobing; Zhu, Zhaohuan; Fung, Jeffrey

2017-06-01

Planets form in gaseous protoplanetary disks surrounding newborn stars. As such, the most direct way to learn how they form from observations, is to directly watch them forming in disks. In the past, this was very difficult due to a lack of observational capabilities; as such, planet formation was largely a subject of pure theoretical astrophysics. Now, thanks to a fleet of new instruments with unprecedented resolving power that have come online recently, we have just started to unveil features in resolve images of protoplanetary disks, such as gaps and spiral arms, that are most likely associated with embedded (unseen) planets. By comparing observations with theoretical models of planet-disk interactions, the masses and orbits of these still forming planets may be constrained. Such planets may help us to directly test various planet formation models. This marks the onset of a new field — observational planet formation. I will introduce the current status of this field.

Les métiers innovants de la formation. Le champ de la formation professionnelle et l'ingénierie de formation à distance

OpenAIRE

Marty, Olivier

2013-01-01

National audience; This document is extracted from a conference for PhD students at La Sorbonne University (Paris) about innovative teaching professions. It describes and analyses the crafts of vocational education as well as public distance education engineering.; Ce document est le support d'une conférence sur les métiers innovants de la formation. Après les définitions d'usage, il décrit et analyse les métiers de la formation professionnelle continue et l'ingénierie de formation à distance...

Types of tectonic structures, sedimentary volcanogenetic formations of a mantle, favourable processes for exogenetic and polygenetic uranium deposits formation

International Nuclear Information System (INIS)

Danchev, V.I.; Komarnitskij, G.M.; Levin, V.N.; Shumlyanskij, V.A.

1985-01-01

Factors, affecting mineralization processes are considered. Characteristic features of uranium-bearing provinces are as follows: the presence of crust of continental type; deep-seated tectonic structures-rises and saggings, roofs, gneiss domes, rift zones and transform fractures; specialization for uranium of sedimentary and magmatic formations; the presence of manifestation regions of deep thermal and gaseous flow, etc. In uranium-bearing provinces territories favourable for the manifestation of different types of uranium mineralization: metamorphogenetic, polygenetic and exogenetic ones, are singled out. Different epochs of uranium ore formation are established. In sedimentary masses tectonic regime and climate are of special importance, and for epigenetic deposits, formed with an aid of underground waters-hydrogeological conditions. In the limits of the main structural elements of the Earth crust and geotectonic structures of higher orders the following types of sedimentary and volcanic formations can be singled out: 1-formations with exogenous uranium mineralization; 2-formations, accumulated in the epochs of epigenous ore formation; 3-formations fav ourable for epigenous uranium deposit formation; 4-formations unfavourable for the formation and localization of uranium mineralization

An Adaptable Seismic Data Format

Science.gov (United States)

Krischer, Lion; Smith, James; Lei, Wenjie; Lefebvre, Matthieu; Ruan, Youyi; de Andrade, Elliott Sales; Podhorszki, Norbert; Bozdağ, Ebru; Tromp, Jeroen

2016-11-01

We present ASDF, the Adaptable Seismic Data Format, a modern and practical data format for all branches of seismology and beyond. The growing volume of freely available data coupled with ever expanding computational power opens avenues to tackle larger and more complex problems. Current bottlenecks include inefficient resource usage and insufficient data organization. Properly scaling a problem requires the resolution of both these challenges, and existing data formats are no longer up to the task. ASDF stores any number of synthetic, processed or unaltered waveforms in a single file. A key improvement compared to existing formats is the inclusion of comprehensive meta information, such as event or station information, in the same file. Additionally, it is also usable for any non-waveform data, for example, cross-correlations, adjoint sources or receiver functions. Last but not least, full provenance information can be stored alongside each item of data, thereby enhancing reproducibility and accountability. Any data set in our proposed format is self-describing and can be readily exchanged with others, facilitating collaboration. The utilization of the HDF5 container format grants efficient and parallel I/O operations, integrated compression algorithms and check sums to guard against data corruption. To not reinvent the wheel and to build upon past developments, we use existing standards like QuakeML, StationXML, W3C PROV and HDF5 wherever feasible. Usability and tool support are crucial for any new format to gain acceptance. We developed mature C/Fortran and Python based APIs coupling ASDF to the widely used SPECFEM3D_GLOBE and ObsPy toolkits.

Planetesimals and Planet Formation

Science.gov (United States)

Chambers, John

The first step in the standard model for planet formation is the growth of gravitationally bound bodies called ``planetesimals'' from dust grains in a protoplanetary disk. Currently, we do not know how planetesimals form, how long they take to form, or what their sizes and mechanical properties are. The goal of this proposal is to assess how these uncertainties affect subsequent stages of planetary growth and the kind of planetary systems that form. The work will address three particular questions: (i) Can the properties of small body populations in the modern Solar System constrain the properties of planetesimals? (ii) How do the properties of planetesimals affect the formation of giant planets? (iii) How does the presence of a water ice condensation front (the ``snow line'') in a disk affect planetesimal formation and the later stages of planetary growth? These questions will be examined with computer simulations of planet formation using new computer codes to be developed as part of the proposal. The first question will be addressed using a statistical model for planetesimal coagulation and fragmentation. This code will be merged with the proposer's Mercury N-body integrator code to model the dynamics of large protoplanets in order to address the second question. Finally, a self- consistent model of disk evolution and the radial transport of water ice and vapour will be added to examine the third question. A theoretical understanding of how planets form is one of the key goals of NASA and the Origins of Solar Systems programme. Researchers have carried out many studies designed to address this goal, but the questions of how planetesimals form and how their properties affect planet formation have received relatively little attention. The proposed work will help address these unsolved questions, and place other research in context by assessing the importance of planetesimal origins and properties for planet formation.

Formation of double layers

International Nuclear Information System (INIS)

Leung, P.; Wong, A.Y.; Quon, B.H.

1981-01-01

Experiments on both stationary and propagating double layers and a related analytical model are described. Stationary double layers were produced in a multiple plasma device, in which an electron drift current was present. An investigation of the plasma parameters for the stable double layer condition is described. The particle distribution in the stable double layer establishes a potential profile, which creates electron and ion beams that excite plasma instabilities. The measured characteristics of the instabilities are consistent with the existence of the double layer. Propagating double layers are formed when the initial electron drift current is large. Ths slopes of the transition region increase as they propagate. A physical model for the formation of a double layer in the experimental device is described. This model explains the formation of the low potential region on the basis of the space charge. This space charge is created by the electron drift current. The model also accounts for the role of ions in double layer formation and explains the formation of moving double layers. (Auth.)

Medusae Fossae Formation

Science.gov (United States)

2002-01-01

(Released 10 April 2002) The Science This THEMIS visible image was acquired near 7o S, 172o W (188o E) and shows a remarkable martian geologic deposit known as the Medusae Fossae Formation. This Formation, seen here as the raised plateau in the upper two-thirds of the image, is a soft, easily eroded deposit that extends for nearly 1,000 km along the equator of Mars. In this region the deposit has been heavily eroded by the wind to produce a series of linear ridges called yardangs. These parallel ridges point in direction of the prevailing winds that carved them, and demonstrate the power of martian winds to sculpt the dry landscape of Mars. The Medusae Fossae Formation has been completely stripped from the surface in the lower third of the image, revealing a harder layer below that is more resistant to wind erosion. The easily eroded nature of the Medusae Fossae Formation suggests that it is composed of weakly cemented particles, and was most likely formed by the deposition of wind-blown dust or volcanic ash. Several ancient craters that were once completely buried by this deposit are being exposed, or exhumed, as the overlying Medusae Formation is removed. Very few impact craters are visible on this Formation, indicating that the surface seen today is relatively young, and that the processes of erosion are likely to be actively occurring. The Story Medusa of Greek mythology fame, the name-giver to this region, had snaky locks of hair that could turn a person to stone. Wild and unruly, this monster of the underworld could certainly wreak havoc on the world of the human imagination. As scary as she was, Medusa would have no advantage over the fierce, masterful winds blowing across Mars, which once carved the streaky, terrain at the top of this image. Wild and whipping, these winds have slowly eroded away the 'topsoil,' revealing ancient craters and other surface features they once covered. The loosely cemented particles of this 'topsoil' are likely made up of dust

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....... Following research based design methodology an experiment separating the two was initiated.This was to provide for more openness and creativity in contrast to a design in which existing relations seem predominant....

Laser filament-induced aerosol formation

Directory of Open Access Journals (Sweden)

H. Saathoff

2013-05-01

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 for the given experimental conditions. 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 oxidized species like acids generated by the photoionization of both major and minor components of the air, including N2, NH3, SO2 and organics.

Automation of Tabular Application Formation

Directory of Open Access Journals (Sweden)

S. V. Zykin

2013-01-01

Full Text Available The paper considers automation problems of the interface formation between a table and a relational database. The task description is formalized and the description of the existing approaches to formation of data representations on an example of widely widespread CASE-tools is submitted. The definition of intermediate data representation as a ”join table” is offered, which is used for maintenance of correctness of data representation formation, and also is necessary for direct and inverse data transformations. On the basis of lossless join property and realized dependencies, the concept and a way of context formation of the application and restrictions is introduced. The considered material is further used for constructing an inverse data transformation from tabular presentation into a relational one. On the basis of relationships properties on a database scheme, the partial order on the relations is established, and the restriction of acyclic databases schemes is introduced. The received results are further used at the analysis of principles of formation of inverse data transformation, and the basic details of such a transformation algorithm are considered.

Decentralized Control for Scalable Quadcopter Formations

Directory of Open Access Journals (Sweden)

Qasim Ali

2016-01-01

Full Text Available An innovative framework has been developed for teamwork of two quadcopter formations, each having its specified formation geometry, assigned task, and matching control scheme. Position control for quadcopters in one of the formations has been implemented through a Linear Quadratic Regulator Proportional Integral (LQR PI control scheme based on explicit model following scheme. Quadcopters in the other formation are controlled through LQR PI servomechanism control scheme. These two control schemes are compared in terms of their performance and control effort. Both formations are commanded by respective ground stations through virtual leaders. Quadcopters in formations are able to track desired trajectories as well as hovering at desired points for selected time duration. In case of communication loss between ground station and any of the quadcopters, the neighboring quadcopter provides the command data, received from the ground station, to the affected unit. Proposed control schemes have been validated through extensive simulations using MATLAB®/Simulink® that provided favorable results.

Frequency formats, probability formats, or problem structure? A test of the nested-sets hypothesis in an extensional reasoning task

Directory of Open Access Journals (Sweden)

William P. Neace

2008-02-01

Full Text Available Five experiments addressed a controversy in the probability judgment literature that centers on the efficacy of framing probabilities as frequencies. The natural frequency view predicts that frequency formats attenuate errors, while the nested-sets view predicts that highlighting the set-subset structure of the problem reduces error, regardless of problem format. This study tested these predictions using a conjunction task. Previous studies reporting that frequency formats reduced conjunction errors confounded reference class with problem format. After controlling this confound, the present study's findings show that conjunction errors can be reduced using either a probability or a frequency format, that frequency effects depend upon the presence of a reference class, and that frequency formats do not promote better statistical reasoning than probability formats.

The NeXus data format.

Science.gov (United States)

Könnecke, Mark; Akeroyd, Frederick A; Bernstein, Herbert J; Brewster, Aaron S; Campbell, Stuart I; Clausen, Björn; Cottrell, Stephen; Hoffmann, Jens Uwe; Jemian, Pete R; Männicke, David; Osborn, Raymond; Peterson, Peter F; Richter, Tobias; Suzuki, Jiro; Watts, Benjamin; Wintersberger, Eugen; Wuttke, Joachim

2015-02-01

NeXus is an effort by an international group of scientists to define a common data exchange and archival format for neutron, X-ray and muon experiments. NeXus is built on top of the scientific data format HDF5 and adds domain-specific rules for organizing data within HDF5 files, in addition to a dictionary of well defined domain-specific field names. The NeXus data format has two purposes. First, it defines a format that can serve as a container for all relevant data associated with a beamline. This is a very important use case. Second, it defines standards in the form of application definitions for the exchange of data between applications. NeXus provides structures for raw experimental data as well as for processed data.

Forces in strategy formation

DEFF Research Database (Denmark)

Steensen, Elmer Fly; Sanchez, Ron

2008-01-01

This chapter proposes that organizational strategy formation should be characterized theoretically as a process that is subject to several interacting forces, rather than represented by separate discrete decisionmodels or theoretic perspectives, as is commonly done in the strategic management...... literature. Based on an extensive review of relevant theory and empirical work in strategic decision-making, organizational change theory, cognitive and social psychology, and strategy processes, seven kinds of ''forces'' - rational, imposed, teleological, learning, political, heuristic, and social...... - are identified as interacting in and having significant influence on the strategy formation process. It is further argued that by applying a holistic ''forces-view'' of the significant and interacting influences on strategy formation, we can better understand the dynamics and challenges in managing the process...

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.

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)

The relationship between sucrose hydrolysis, sorbitol formation and mineral ion concentration during bioethanol formation using Zymomonas mobilis 2716

Energy Technology Data Exchange (ETDEWEB)

Doelle, M.B.; Doelle, H.W. (Queensland Univ., St. Lucia (Australia). Dept. of Microbiology); Greenfield, P.F. (Queensland Univ., St. Lucia (Australia). Dept. of Chemical Engineering)

1990-11-01

Investigations into the relationship between sucrose hydrolysis, sorbitol formation and mineral ion concentration during bioethanol formation by Zymomonas mobilis 2716 revealed two distinct phenomena responsible for carbon flow diversion, a 'sucrose effect' and a 'salt effect'. Neither of the two phenomena affects sucrose hydrolysis, but they divert carbon flow of the fructose monomer leading to its own accumulation, sorbitol or oligosaccharide formation. Sucrose concentrations in excess of 15% (w/v) led to sorbitol formation, the level of which may exceed 2% (w/v) depending upon glucose accumulation during sucrose hydrolysis. Increasing mineral ion concentrations led initially to carbon losses and finally to fructose accumulation instead of sorbitol formation. This carbon loss can be corrected by the addition of invertase, which in turn leads to an increase in sorbitol, fructose and ethanol. Potassium and chloride are the dominant ions responsible for suppression of sorbitol formation and fructose uptake, encouraging oligosaccharide formation. These fructooligosaccharides must be of a type which can be converted to fructose, sorbitol and ethanol through the action of invertase. The requirement of invertase addition to prevent fructooligosaccharide formation is indirect evidence that Z. mobilis 2716 does not produce invertase. (orig.).

ENDF/B-5 formats manual 1984

Energy Technology Data Exchange (ETDEWEB)

Kinsey, R; Magurno, B A

1986-09-01

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) Figs, tabs

Stratigraphy and dissolution of the Rustler Formation

International Nuclear Information System (INIS)

Bachman, G.O.

1987-01-01

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

Star Formation in low mass galaxies

Science.gov (United States)

Mehta, Vihang

2018-01-01

Our current hierarchical view of the universe asserts that the large galaxies we see today grew via mergers of numerous smaller galaxies. As evidenced by recent literature, the collective impact of these low mass galaxies on the universe is more substantial than previously thought. Studying the growth and evolution of these low mass galaxies is critical to our understanding of the universe as a whole. Star formation is one of the most important ongoing processes in galaxies. Forming stars is fundamental to the growth of a galaxy. One of the main goals of my thesis is to analyze the star formation in these low mass galaxies at different redshifts.Using the Hubble UltraViolet Ultra Deep Field (UVUDF), I investigate the star formation in galaxies at the peak of the cosmic star formation history using the ultraviolet (UV) light as a star formation indicator. Particularly, I measure the UV luminosity function (LF) to probe the volume-averaged star formation properties of galaxies at these redshifts. The depth of the UVUDF is ideal for a direct measurement of the faint end slope of the UV LF. This redshift range also provides a unique opportunity to directly compare UV to the "gold standard" of star formation indicators, namely the Hα nebular emission line. A joint analysis of the UV and Hα LFs suggests that, on average, the star formation histories in low mass galaxies (~109 M⊙) are more bursty compared to their higher mass counterparts at these redshifts.Complementary to the analysis of the average star formation properties of the bulk galaxy population, I investigate the details of star formation in some very bursty galaxies at lower redshifts selected from Spitzer Large Area Survey with Hyper-Suprime Cam (SPLASH). Using a broadband color-excess selection technique, I identify a sample of low redshift galaxies with bright nebular emission lines in the Subaru-XMM Deep Field (SXDF) from the SPLASH-SXDF catalog. These galaxies are highly star forming and have

Standard exercise report format (SERF)

International Nuclear Information System (INIS)

Anon.

1995-01-01

This talk summarizes the reasons for the development of draft SERF the Standard Exercise Report Format used for reporting the results of emergency preparedness exercises, and gives a summary of the format and rational behind it

Heating systems for heating subsurface formations

Science.gov (United States)

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.

Formation of topological defects

International Nuclear Information System (INIS)

Vachaspati, T.

1991-01-01

We consider the formation of point and line topological defects (monopoles and strings) from a general point of view by allowing the probability of formation of a defect to vary. To investigate the statistical properties of the defects at formation we give qualitative arguments that are independent of any particular model in which such defects occur. These arguments are substantiated by numerical results in the case of strings and for monopoles in two dimensions. We find that the network of strings at formation undergoes a transition at a certain critical density below which there are no infinite strings and the closed-string (loop) distribution is exponentially suppressed at large lengths. The results are contrasted with the results of statistical arguments applied to a box of strings in dynamical equilibrium. We argue that if point defects were to form with smaller probability, the distance between monopoles and antimonopoles would decrease while the monopole-to-monopole distance would increase. We find that monopoles are always paired with antimonopoles but the pairing becomes clean only when the number density of defects is small. A similar reasoning would also apply to other defects

Method for detecting and locating sand-producing zones in friable, unconsolidated sandstone formations of subterranean formations

International Nuclear Information System (INIS)

Sparlin, D.D.

1976-01-01

A sand-producing zone in a friable, unconsolidated sandstone formation traversed by a well bore is found by first introducing into the reservoir about 0.1--10 gallons of a radioactive mixture per foot of vertical formation being treated, the mixture containing about 0.1--1 lb of radioactive material per gallon of carrier fluid. A dispersing agent containing a deemulsifying surfactant may then be injected into the formation. The radioactivity in the well bore is recorded and the reservoir is returned to production. Another radioactivity log is run and a decrease in radioactivity indicates the location of the sand-producing portions of the formation

Formative Constructs Implemented via Common Factors

Science.gov (United States)

Treiblmaier, Horst; Bentler, Peter M.; Mair, Patrick

2011-01-01

Recently there has been a renewed interest in formative measurement and its role in properly specified models. Formative measurement models are difficult to identify, and hence to estimate and test. Existing solutions to the identification problem are shown to not adequately represent the formative constructs of interest. We propose a new two-step…

Seismic attributes and advanced computer algorithm to predict formation pore pressure: Qalibah formation of Northwest Saudi Arabia

Science.gov (United States)

Nour, Abdoulshakour M.

Oil and gas exploration professionals have long recognized the importance of predicting pore pressure before drilling wells. Pre-drill pore pressure estimation not only helps with drilling wells safely but also aids in the determination of formation fluids migration and seal integrity. With respect to the hydrocarbon reservoirs, the appropriate drilling mud weight is directly related to the estimated pore pressure in the formation. If the mud weight is lower than the formation pressure, a blowout may occur, and conversely, if it is higher than the formation pressure, the formation may suffer irreparable damage due to the invasion of drilling fluids into the formation. A simple definition of pore pressure is the pressure of the pore fluids in excess of the hydrostatic pressure. In this thesis, I investigated the utility of advance computer algorithm called Support Vector Machine (SVM) to learn the pattern of high pore pressure regime, using seismic attributes such as Instantaneous phase, t*Attenuation, Cosine of Phase, Vp/Vs ratio, P-Impedance, Reflection Acoustic Impedance, Dominant frequency and one well attribute (Mud-Weigh) as the learning dataset. I applied this technique to the over pressured Qalibah formation of Northwest Saudi Arabia. The results of my research revealed that in the Qalibah formation of Northwest Saudi Arabia, the pore pressure trend can be predicted using SVM with seismic and well attributes as the learning dataset. I was able to show the pore pressure trend at any given point within the geographical extent of the 3D seismic data from which the seismic attributes were derived. In addition, my results surprisingly showed the subtle variation of pressure within the thick succession of shale units of the Qalibah formation.

Consensus formation on coevolving networks: groups' formation and structure

International Nuclear Information System (INIS)

Kozma, Balazs; Barrat, Alain

2008-01-01

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

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

Teacher perspectives about using formative assessment

DEFF Research Database (Denmark)

Evans, Robert Harry; Clesham, Rose; Dolin, Jens

2018-01-01

This chapter examines three different classroom teacher perspectives when using ASSIST-ME project formative assessment methods as described in the introductory chapter. The first ‘teacher perspective’ is about changes in teacher self-efficacies while using formative assessment methods as monitored...... by a pre- and post-teacher questionnaire. Teachers who tried the unfamiliar formative methods of assessment (see introductory book chapter for these methods) as well as their colleagues who did not were surveyed. The second ‘teacher perspective’ examines changes in teachers’ subjective theories while...... trying project-specific formative assessment methods in Czech Republic. Analyses are done through case studies and interviews. The final part of the chapter looks at teacher perspectives while using an Internet-based application to facilitate formative assessment. The teacher use of the application...

COMPETENCYTHE FORMATION FOR LIFE

Directory of Open Access Journals (Sweden)

Milagros Mederos-Piñeiro

2016-07-01

Full Text Available The formation of life competences is the result of a quality education that prepares students to meet the challenges of a fast moving world where equality and equal opportunities should constitute premises of education; training them is a challenge teachers to assume new generations contribute actively to a better world. In Cuba are important research on the formation of communication competences and self-regulated learning in primary school. The paper shows the result of an investigation that provides a methodology for the formation of life competences in primary school education, used as an essential pathway research activity. The methodological approach of research has a quantitative approach and an explanatory scope to establish and make sense of understanding the causal relationship between the direction of research activity and training of life competences. Theoretical, empirical and mathematical-statistical, for characterizing the initial state, processing of results and analysis: research methods are used. The application of the methodology for the formation of life competences makes teachers lead the teaching-learning process with a research and transforming teaching concept, where the school is the protagonist of their learning and causes changes in their performances, which are evident in the formed competences related to effective and affective communication; the solution of problems related to life; the use of means in obtaining the knowledge and the expression of a behavior consistent with school and social demands. The effectiveness of the methodology confirms that there is a causal relationship between the direction of research activity by teachers and the formation of life competences in school.

The Physics of Planetesimal Formation

Science.gov (United States)

Simon, Jacob; Armitage, Philip; Youdin, Andrew; Li, Rixin

2015-12-01

Planetesimals are the precursors to planets, and understanding their formation is an essential step towards developing a complete theory of planet formation. For small solid particles (e.g., dust grains) to coagulate into planetesimals, however, requires that these particles grow beyond centimeter sizes; with traditional coagulation physics, this is very difficult. The streaming instability, which is a clumping process akin to the pile-up of cars in a traffic jam, generates sufficiently high solid densities that the mutual gravity between the clumped particles eventually causes their collapse towards planetesimal mass and size scales. Exploring this transition from dust grains to planetesimals is still in its infancy but is extremely important if we want to understand the basics of planet formation. Here, I present a series of high resolution, first principles numerical simulations of potoplanetary disk gas and dust to study the clumping of particles via the streaming instability and the subsequent collapse towards planetesimals. These simulations have been employed to characterize the planetesimal population as a function of radius in protoplanetary disks. The results of these simulations will be crucial for planet formation models to correctly explain the formation and configuration of solar systems.

Formation of galaxies

International Nuclear Information System (INIS)

Szalay, A.S.

1984-12-01

The present theories of galaxy formation are reviewed. The relation between peculiar velocities and the correlation function of galaxies points to the possibility that galaxies do not form uniformly everywhere. Scale invariant properties of the cluster-cluster correlations are discussed. Comparing the correlation functions in a dimensionless way, galaxies appear to be stronger clustered, in contrast with the comparison of the dimensional amplitudes of the correlation functions. Theoretical implications of several observations as Lyman-α clouds, correlations of faint galaxies are discussed. None of the present theories of galaxy formation can account for all facts in a natural way. 29 references

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, Anna 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.

Process for fracturing underground formations

Energy Technology Data Exchange (ETDEWEB)

Kiel, O M

1974-01-25

This invention concerns a process for fracturing underground formations and has as one object the mixing of viscous compositions. Through a borehole, a fluid is injected into the formation. This fluid contains a complex prepared by the reaction of an aliphatic quaternary ammonium compound with a water-soluble compound chosen from monosaccharides, disaccharides, trisaccharides, polysaccharides, and synthetic hydroxylated polymers with long chains. These complexes are formed at temperatures between 20/sup 0/ and 205/sup 0/C. The process also includes production of formation fluid into the borehole.

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

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.

Formative (measurement)

NARCIS (Netherlands)

Fassott, G.; Henseler, Jörg; Cooper, C.; Lee, N.; Farrell, A.

2015-01-01

When using measurement models with multiple indicators, researchers need to decide about the epistemic relationship between the latent variable and its indicators. In this article, we describe the nature, the estimation, the characteristics, and the validity assessment of formative measurement

FORMATIVE ASSESSMENT IN EFL CLASSROOM PRACTICES

Directory of Open Access Journals (Sweden)

Ida Ayu Made Sri Widiastuti

2017-03-01

Full Text Available This study investigated the challenges and opportunities of formative assessment in EFL classes. It made use of qualitative research design by using indepth interviews to collect the required data. Three teachers and three students were involved as research participants in this study and they were intensively interviewed to get valid and reliable data regarding their understanding of formative assessment and the follow up actions they took after implementing formative assessment. The results of this study showed that the English teachers were found not to take appropriate follow up actions due to their low understanding of formative assessment. The teachers’ understanding could influence their ability in deciding the actions. This study indicates that EFL teachers need urgent further intensive training on the appropriate implementation of formative assessment and how follow up actions should be integrated into classroom practices

Formation Control for the MAXIM Mission

Science.gov (United States)

Luquette, Richard J.; Leitner, Jesse; Gendreau, Keith; Sanner, Robert M.

2004-01-01

Over the next twenty years, a wave of change is occurring in the space-based scientific remote sensing community. While the fundamental limits in the spatial and angular resolution achievable in spacecraft have been reached, based on today s technology, an expansive new technology base has appeared over the past decade in the area of Distributed Space Systems (DSS). A key subset of the DSS technology area is that which covers precision formation flying of space vehicles. Through precision formation flying, the baselines, previously defined by the largest monolithic structure which could fit in the largest launch vehicle fairing, are now virtually unlimited. Several missions including the Micro-Arcsecond X-ray Imaging Mission (MAXIM), and the Stellar Imager will drive the formation flying challenges to achieve unprecedented baselines for high resolution, extended-scene, interferometry in the ultraviolet and X-ray regimes. This paper focuses on establishing the feasibility for the formation control of the MAXIM mission. MAXIM formation flying requirements are on the order of microns, while Stellar Imager mission requirements are on the order of nanometers. This paper specifically addresses: (1) high-level science requirements for these missions and how they evolve into engineering requirements; and (2) the development of linearized equations of relative motion for a formation operating in an n-body gravitational field. Linearized equations of motion provide the ground work for linear formation control designs.

DNA methylation and memory formation.

Science.gov (United States)

Day, Jeremy J; Sweatt, J David

2010-11-01

Memory formation and storage require long-lasting changes in memory-related neuronal circuits. Recent evidence indicates that DNA methylation may serve as a contributing mechanism in memory formation and storage. These emerging findings suggest a role for an epigenetic mechanism in learning and long-term memory maintenance and raise apparent conundrums and questions. For example, it is unclear how DNA methylation might be reversed during the formation of a memory, how changes in DNA methylation alter neuronal function to promote memory formation, and how DNA methylation patterns differ between neuronal structures to enable both consolidation and storage of memories. Here we evaluate the existing evidence supporting a role for DNA methylation in memory, discuss how DNA methylation may affect genetic and neuronal function to contribute to behavior, propose several future directions for the emerging subfield of neuroepigenetics, and begin to address some of the broader implications of this work.

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.

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.

Making the invisible visible: improved electrospray ion formation of metalloporphyrins/-phthalocyanines by attachment of the formate anion (HCOO(-)).

Science.gov (United States)

Hitzenberger, Jakob Felix; Dammann, Claudia; Lang, Nina; Lungerich, Dominik; García-Iglesias, Miguel; Bottari, Giovanni; Torres, Tomás; Jux, Norbert; Drewello, Thomas

2016-02-21

A protocol is developed for the coordination of the formate anion (HCOO(-)) to neutral metalloporphyrins (Pors) and -phthalocyanines (Pcs) containing divalent metals as a means to improve their ion formation in electrospray ionization (ESI). This method is particularly useful when the oxidation of the neutral metallomacrocycle fails. While focusing on Zn(II)Pors and Zn(II)Pcs, we show that formate is also readily attached to Mn(II), Mg(II) and Co(II)Pcs. However, for the Co(II)Pc secondary reactions can be observed. Upon collision-induced dissociation (CID), Zn(II)Por/Pc·formate supramolecular complexes can undergo the loss of CO2 in combination with transfer of a hydride anion (H(-)) to the zinc metal center. Further dissociation leads to electron transfer and hydrogen atom loss, generating a route to the radical anion of the Zn(II)Por/Pc without the need for electrochemical reduction, although the Zn(II)Por/Pc may have a too low electron affinity to allow electron transfer directly from the formate anion. In addition to single Por molecules, multi Por arrays were successfully analyzed by this method. In this case, multiple addition of formate occurs, giving rise to multiply charged species. In these multi Por arrays, complexation of the formate anion occurs by two surrounding Por units (sandwich). Therefore, the maximum attainment of formate anions in these arrays corresponds to the number of such sandwich complexes rather than the number of porphyrin moieties. The same bonding motif leads to dimers of the composition [(Zn(II)Por/Pc)2·HCOO](-). In these, the formate anion can act as a structural probe, allowing the distinction of isomeric ions with the formate bridging two macrocycles or being attached to a dimer of directly connected macrocycles.

Maggot excretions inhibit biofilm formation on biomaterials.

Science.gov (United States)

Cazander, Gwendolyn; van de Veerdonk, Mariëlle C; Vandenbroucke-Grauls, Christina M J E; Schreurs, Marco W J; Jukema, Gerrolt N

2010-10-01

Biofilm-associated infections in trauma surgery are difficult to treat with conventional therapies. Therefore, it is important to develop new treatment modalities. Maggots in captured bags, which are permeable for larval excretions/secretions, aid in healing severe, infected wounds, suspect for biofilm formation. Therefore we presumed maggot excretions/secretions would reduce biofilm formation. We studied biofilm formation of Staphylococcus aureus, Staphylococcus epidermidis, Klebsiella oxytoca, Enterococcus faecalis, and Enterobacter cloacae on polyethylene, titanium, and stainless steel. We compared the quantities of biofilm formation between the bacterial species on the various biomaterials and the quantity of biofilm formation after various incubation times. Maggot excretions/secretions were added to existing biofilms to examine their effect. Comb-like models of the biomaterials, made to fit in a 96-well microtiter plate, were incubated with bacterial suspension. The formed biofilms were stained in crystal violet, which was eluted in ethanol. The optical density (at 595 nm) of the eluate was determined to quantify biofilm formation. Maggot excretions/secretions were pipetted in different concentrations to (nonstained) 7-day-old biofilms, incubated 24 hours, and finally measured. The strongest biofilms were formed by S. aureus and S. epidermidis on polyethylene and the weakest on titanium. The highest quantity of biofilm formation was reached within 7 days for both bacteria. The presence of excretions/secretions reduced biofilm formation on all biomaterials. A maximum of 92% of biofilm reduction was measured. Our observations suggest maggot excretions/secretions decrease biofilm formation and could provide a new treatment for biofilm formation on infected biomaterials.

Method of developing thick sloping coal formations

Energy Technology Data Exchange (ETDEWEB)

Bragintsev, V F; Mashkovtsev, I L; Semenov, V S; Zykov, V N

1980-04-25

A method is patented for developing thick sloping coal formations in 3 inclined layers. It includes conducting developmental operations for each of the layers until one begins the last one and extraction of the layers. In order to improve effectivess and extraction operation safety one first carried out preliminary development of a formation in thin strips beneath protected objects when extracting formation which contain alot of gas. Then one removes the gas of a formation through boreholes that have been drilled into the formation from the indicated workings. Then one works the upper layer in thin strips in a sequence from the roof of the formation to the floor of the upper layer. The one strengthens roof rock of the formation by pumping in a quickly hardening solution into the boreholes which have been drilled into the roof of the formation after processing the upper layer. The middle layer is worked in thin strips in the sequence from the roof to the ground of the middle layer, then the lower layer of the formation is strengthened by pumping in quickly hardening solution into the formation along degasified boreholes and it is worked in thin strips in sequence from the ground of the lower to its roof. Workings are shaped respectively for the middle and lower layers by deepening workings of the upper and middle layers. The layers are worked respectively after finishing displacement of the roof in front of the extraction face of each subsequent extraction of a layer in alternating fashion.

Insights from simulations of star formation

International Nuclear Information System (INIS)

Larson, Richard B

2007-01-01

Although the basic physics of star formation is classical, numerical simulations have yielded essential insights into how stars form. They show that star formation is a highly nonuniform runaway process characterized by the emergence of nearly singular peaks in density, followed by the accretional growth of embryo stars that form at these density peaks. Circumstellar discs often form from the gas being accreted by the forming stars, and accretion from these discs may be episodic, driven by gravitational instabilities or by protostellar interactions. Star-forming clouds typically develop filamentary structures, which may, along with the thermal physics, play an important role in the origin of stellar masses because of the sensitivity of filament fragmentation to temperature variations. Simulations of the formation of star clusters show that the most massive stars form by continuing accretion in the dense cluster cores, and this again is a runaway process that couples star formation and cluster formation. Star-forming clouds also tend to develop hierarchical structures, and smaller groups of forming objects tend to merge into progressively larger ones, a generic feature of self-gravitating systems that is common to star formation and galaxy formation. Because of the large range of scales and the complex dynamics involved, analytic models cannot adequately describe many aspects of star formation, and detailed numerical simulations are needed to advance our understanding of the subject. 'The purpose of computing is insight, not numbers.' Richard W Hamming, in Numerical Methods for Scientists and Engineers (1962) 'There are more things in heaven and earth, Horatio, than are dreamt of in your philosophy.' William Shakespeare, in Hamlet, Prince of Denmark (1604) (key issues review)

Insights from simulations of star formation

Energy Technology Data Exchange (ETDEWEB)

Larson, Richard B [Department of Astronomy, Yale University, Box 208101, New Haven, CT 06520-8101 (United States)

2007-03-15

Although the basic physics of star formation is classical, numerical simulations have yielded essential insights into how stars form. They show that star formation is a highly nonuniform runaway process characterized by the emergence of nearly singular peaks in density, followed by the accretional growth of embryo stars that form at these density peaks. Circumstellar discs often form from the gas being accreted by the forming stars, and accretion from these discs may be episodic, driven by gravitational instabilities or by protostellar interactions. Star-forming clouds typically develop filamentary structures, which may, along with the thermal physics, play an important role in the origin of stellar masses because of the sensitivity of filament fragmentation to temperature variations. Simulations of the formation of star clusters show that the most massive stars form by continuing accretion in the dense cluster cores, and this again is a runaway process that couples star formation and cluster formation. Star-forming clouds also tend to develop hierarchical structures, and smaller groups of forming objects tend to merge into progressively larger ones, a generic feature of self-gravitating systems that is common to star formation and galaxy formation. Because of the large range of scales and the complex dynamics involved, analytic models cannot adequately describe many aspects of star formation, and detailed numerical simulations are needed to advance our understanding of the subject. 'The purpose of computing is insight, not numbers.' Richard W Hamming, in Numerical Methods for Scientists and Engineers (1962) 'There are more things in heaven and earth, Horatio, than are dreamt of in your philosophy.' William Shakespeare, in Hamlet, Prince of Denmark (1604) (key issues review)

Galaxy formation and evolution

CERN Document Server

Mo, Houjun; White, Simon

2010-01-01

The rapidly expanding field of galaxy formation lies at the interface between astronomy, particle physics, and cosmology. Covering diverse topics from these disciplines, all of which are needed to understand how galaxies form and evolve, this book is ideal for researchers entering the field. Individual chapters explore the evolution of the Universe as a whole and its particle and radiation content; linear and nonlinear growth of cosmic structure; processes affecting the gaseous and dark matter components of galaxies and their stellar populations; the formation of spiral and elliptical galaxies; central supermassive black holes and the activity associated with them; galaxy interactions; and the intergalactic medium. Emphasizing both observational and theoretical aspects, this book provides a coherent introduction for astronomers, cosmologists, and astroparticle physicists to the broad range of science underlying the formation and evolution of galaxies.

Output formatting in Apple-Soft Basic

International Nuclear Information System (INIS)

Navale, A.S.

1987-01-01

Personal computers are being used extensively in various fields. BASIC is a very popular and widely used language in personal computers. Apple computer is one of the popular machines used for scientific and engineering applications. Presenting output from computers in a neat and easy to read form is very important. Languages like FORTRAN have utility command 'FORMAT' which takes care of the formatting of the output in user-defined form. In some versions of BASIC a PRINT USING facility is available but it is not as powerful as the FORTRAN statement 'FORMAT'. Applesoft basic does not have even this PRINT USING command. Programmers have to write their own program segments to handle output formatting in Applesoft BASIC. Generally, such user written programs are of limited use as they cannot be used easily with other programs. A general purpose and easily transportable subroutine in Applesoft BASIC is presented here for handling output formatting in user-defined structure. The subroutine is nearly as powerful as the FORMAT statement in FORTRAN. It can also be used in other versions of BASIC with very little modifications. 3 tables, 4 refs. (author)

Heating tar sands formations while controlling pressure

Science.gov (United States)

Stegemeier, George Leo [Houston, TX; Beer, Gary Lee [Houston, TX; Zhang, Etuan [Houston, TX

2010-01-12

Methods for treating a tar sands formation are described herein. Methods may include heating at least a section of a hydrocarbon layer in the formation from a plurality of heaters located in the formation. A pressure in the majority of the section may be maintained below a fracture pressure of the formation. The pressure in the majority of the section may be reduced to a selected pressure after the average temperature reaches a temperature that is above 240.degree. C. and is at or below pyrolysis temperatures of hydrocarbons in the section. At least some hydrocarbon fluids may be produced from the formation.

Formation of the oil composition of the Yu0 Bazhenov formation, Salym oil field

Directory of Open Access Journals (Sweden)

E.V. Soboleva

2017-05-01

Full Text Available The Bazhenov horizon of Western Siberia has been studied in considerable detail from different perspectives and different methods, a large number of studies have been devoted to a wide range of issues related to the lithological composition of rocks, their reservoir properties, the study of organic matter, properties and composition of oil at various analytical levels, and many others. This work is devoted to restoring conditions for the formation of oil properties and composition of the Yu0 Salym oil field, based mainly on the geochemical aspects of the study of oil changes both in area and in the section within the productive layer of Salym structure, using some geological data, such as structural plan for the reflecting horizon B (the roof of the Bazhenov formation, having a complex configuration, reservoir temperatures and pressure, well flow rates, and others. There is no single reservoir at the Salym field in the Yu0 formation. For the conclusions of the geological-geochemical interpretation, a sampling of 61 samples of oil from exploration, appraisal and production wells of the initial stages of production was used, since in the future when oil is extracted, the ecology in the deposits changes, and 21 samples of oil from other fields in the West Siberian oil and gas basin. Conventionally, three types of oils are distinguished, differing in their physicochemical parameters, group hydrocarbon and molecular composition. It was suggested that in addition to the own organic matter of the Bazhenov formation, hydrocarbon fluids of the Vasyugan, Tyumen formations and possibly Paleozoic rocks were involved in the formation of the oil composition. The flow of light liquid hydrocarbons and gases occurred along the zones of faults of different genesis and duration of existence.

Lunar recession encoded in tidal rhythmites: a selective overview with examples from Argentina

Science.gov (United States)

de Azarevich, Vanina L. López; Azarevich, Miguel B.

2017-08-01

The study of tides from the sedimentary record of tidal rhythmites, applying fast Fourier transform analysis, contributes to the understanding of the surficial evolution of our highly dynamic planet, and of the astronomical cycles that influenced the ancient tidal systems. This overview of lunar retreat rates, which includes examples from Argentina, displays a generalized pattern of nonlinear, progressively extended lunar cycles up to the present day. The lunar retreat calculated at different stages of the Earth's history identifies three time spans of extremely high recession rates, amounting to almost twice that of the present day: Archean-Paleoproterozoic (6.93 cm/year), Neoproterozoic I-Ediacaran (7.01 cm/year) and Ediacaran-early Cambrian (6.48 cm/year). Older comparable recession rates are difficult to recognize because of the lack of tidal rhythmic sequences. The maximum lunar retreat rate is registered after the Copernican meteor bombardment event on the Moon at 900 Ma, and the time span coincides with the continental dispersal of Rodinia. Every acceleration of the lunar retreat rate coincides with two main processes: (1) meteorite impacts on the Earth or Moon, and (2) reconfiguration of landmasses accompanied by earthquakes that generated changes in the rotational axis of the Earth, inundation surfaces, and glaciation/deglaciation processes. The simultaneous occurrence of such processes makes it difficult to distinguish the causes and effects of each individual process, but its conjunction would have promoted the destabilization of the Earth-Moon system in terms of moment of inertia that was transferred to the Moon rotation.

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...

Formation aux TICE des formateurs d’enseignants : un tissage entre formation et autoformation

Directory of Open Access Journals (Sweden)

Pierre-François Coen

2012-01-01

Full Text Available Cette recherche exploratoire rend compte des modalités de formation des formateurs d’enseignants dans deux établissements d’enseignement du canton de Fribourg, en Suisse. Neuf formateurs d’enseignants ont été interrogés sur leurs parcours de formation et d’autoformation en matière de compétences technologiques et d’intégration des TICE. Les résultats montrent que, même si ces formateurs ont acquis des compétences technologiques, les dispositifs d’enseignement-apprentissage qu’ils mettent en place pour former de futurs enseignants intègrent relativement peu les TICE. En outre, les propos tenus montrent que les formateurs déploient des stratégies d’autoformation plus ou moins efficaces et coûteuses en temps pour les aspects techniques, mais n’usent presque jamais de ce type de procédé pour développer une intégration pédagogique des TICE dans leurs cours. La fin de l’article reprend ces éléments et les discute en essayant de présenter quelques pistes en articulant formation formelle et informelle dans le contexte de la formation des enseignants.

Processes and problems in secondary star formation

International Nuclear Information System (INIS)

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 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

Processes and problems in secondary star formation

International Nuclear Information System (INIS)

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

1985-01-01

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 observational data presently available. We discuss the role of turbulence to produce clumpy cloud structures and introduce new work on colliding intercloud gas flows leading to nonlinear inhomogeneous cloud structures in an initially 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 -- 1-3 x 10/sup 4/ yr and could account for the recent evidence for new massive star formation in several ultracompact H II 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 multi-dimensional calculations of coupled processes. Important nonlinear interactions include hydrodynamics, radiation transport, and magnetic fields

Professional Development through Formative Evaluation

Science.gov (United States)

Nsibande, Rejoice; Garraway, James

2011-01-01

Formative evaluation and its associated methodology of reflection on practice are used extensively in academic staff development. In reflecting on formative evaluation processes in both more traditional and newer programmes conducted at a university of technology, a number of variables reported in the literature were observed to have influenced…

Analysis of constituents of earth formations

International Nuclear Information System (INIS)

Hertzog, R.C.; Grau, J.A.

1981-01-01

The composition of an earth formation is investigated by repetitively irradiating the formation with bursts of neutrons from a source and measuring an energy spectrum of the scattering gamma rays resulting from such irradiation e.g. by photomultiplier or solid state detector. The measured spectrum is thereafter analyzed by comparing it with a composite spectrum, made up of standard spectra, measured in a controlled environment, of constituents postulated to comprise the formation. As a result of such analysis, the proportions of the postulated constituents in the formation are determined. Since the measured spectrum is subject to degradation due to changes in the resolution of the detector, a filtering arrangement effects modification of the standard spectra in a manner which compensates for the changes in the detector and thereby provides for a more accurate determination of the constituents of the formation. Temperature is measured by sensor to compensate for temperature dependence of detector resolution. (author)

Transient Exciplex Formation Electron Transfer Mechanism

OpenAIRE

Michael G. Kuzmin; Irina V. Soboleva; Elena V. Dolotova

2011-01-01

Transient exciplex formation mechanism of excited-state electron transfer reactions is analyzed in terms of experimental data on thermodynamics and kinetics of exciplex formation and decay. Experimental profiles of free energy, enthalpy, and entropy for transient exciplex formation and decay are considered for several electron transfer reactions in various solvents. Strong electronic coupling in contact pairs of reactants causes substantial decrease of activation energy relative to that for c...

Regulation of Reactionary Dentine Formation.

Science.gov (United States)

Neves, V C M; Sharpe, P T

2018-04-01

During the treatment of dental caries that has not penetrated the tooth pulp, maintenance of as much unaffected dentine as possible is a major goal during the physical removal of decayed mineral. Damage to dentine leads to release of fossilized factors (transforming growth factor-β [TGF-β] and bone morphogenic protein [BMP]) in the dentine that are believed to stimulate odontoblasts to secrete new "tertiary" dentine (reactionary dentine). This is formed on the pulpal surface of existing dentine and rethickens the dentine. We have previously shown that activation of Wnt/β-catenin signaling is pivotal for tooth repair in exposed pulp injury, and the pathway can be activated by small-molecule GSK-3 antagonists, resulting in enhanced reparative dentine formation. Here, we use a nonexposed pulp injury model to investigate the mechanisms of reactionary dentine formation in vivo, using small molecules to modulate the Wnt/β-catenin, TGF-β, and BMP pathways. We found that a local increase of Wnt activation at the injury site enhances reactionary dentine secretion. In addition, inhibition of TGF-β, BMP, or Wnt pathways does not impede reactionary dentine formation, although inhibition of TGF-β and/or BMP signaling does result in more disorganized, nontubular reactionary dentine. This suggests that Wnt/β-catenin signaling plays no major role in the formation of reactionary dentine, but in common with reparative dentine formation, exogenous elevation of Wnt/β-catenin signaling can enhance tertiary dentine formation. Release of latent TGF-β or BMPs from dentine is not required for the deposition of mineral to form reactionary dentine but does play a role in its organization.

{alpha}-Man monolayer formation via Si-C bond formation and protein recognition

Energy Technology Data Exchange (ETDEWEB)

Funato, Koji [School of Materials Science, Japan Advanced Institute of Science and Technology, 1-1 Asahidai, Nomi, Ishikawa 923-1292 (Japan); Shirahata, Naoto [National Institute for Materials Science (NIMS), 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan); Miura, Yoshiko, E-mail: miuray@jaist.ac.j [School of Materials Science, Japan Advanced Institute of Science and Technology, 1-1 Asahidai, Nomi, Ishikawa 923-1292 (Japan)

2009-11-30

An acetylenyl-terminated saccharide was synthesized and the thin layer formation on the hydrogen-terminated silicon was investigated. The acetylenyl-terminated saccharide was synthesized by the condensation reaction of hexynoic acid and p-aminophenyl saccharide. This was reacted with hydrogen-terminated silicon (Si-H) by a photochemical reaction. The resulting saccharide modified substrate was analyzed by ellipsometry and X-ray photoelectron spectroscopy, which showed the formation of a uniform monolayer. The surface's ability to recognize proteins was analyzed by fluorescent microscopy, and showed specific interactions with sugar recognition proteins.

Inside-out planet formation

International Nuclear Information System (INIS)

Chatterjee, Sourav; Tan, Jonathan C.

2014-01-01

The compact multi-transiting planet systems discovered by Kepler challenge planet formation theories. Formation in situ from disks with radial mass surface density, Σ, profiles similar to the minimum mass solar nebula but boosted in normalization by factors ≳ 10 has been suggested. We propose that a more natural way to create these planets in the inner disk is formation sequentially from the inside-out via creation of successive gravitationally unstable rings fed from a continuous stream of small (∼cm-m size) 'pebbles', drifting inward via gas drag. Pebbles collect at the pressure maximum associated with the transition from a magnetorotational instability (MRI)-inactive ('dead zone') region to an inner MRI-active zone. A pebble ring builds up until it either becomes gravitationally unstable to form an ∼1 M ⊕ planet directly or induces gradual planet formation via core accretion. The planet may undergo Type I migration into the active region, allowing a new pebble ring and planet to form behind it. Alternatively, if migration is inefficient, the planet may continue to accrete from the disk until it becomes massive enough to isolate itself from the accretion flow. A variety of densities may result depending on the relative importance of residual gas accretion as the planet approaches its isolation mass. The process can repeat with a new pebble ring gathering at the new pressure maximum associated with the retreating dead-zone boundary. Our simple analytical model for this scenario of inside-out planet formation yields planetary masses, relative mass scalings with orbital radius, and minimum orbital separations consistent with those seen by Kepler. It provides an explanation of how massive planets can form with tightly packed and well-aligned system architectures, starting from typical protoplanetary disk properties.

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.

STAR FORMATION IN DISK GALAXIES. II. THE EFFECT OF STAR FORMATION AND PHOTOELECTRIC HEATING ON THE FORMATION AND EVOLUTION OF GIANT MOLECULAR CLOUDS

International Nuclear Information System (INIS)

Tasker, Elizabeth J.

2011-01-01

We investigate the effect of star formation and diffuse photoelectric heating on the properties of giant molecular clouds (GMCs) formed in high-resolution (∼ H,c >100 cm -3 are identified as GMCs. Between 1000 and 1500 clouds are created in the simulations with masses M>10 5 M sun and 180-240 with masses M>10 6 M sun in agreement with estimates of the Milky Way's population. We find that the effect of photoelectric heating is to suppress the fragmentation of the interstellar medium, resulting in a filamentary structure in the warm gas surrounding clouds. This environment suppresses the formation of a retrograde rotating cloud population, with 88% of the clouds rotating prograde with respect to the galaxy after 300 Myr. The diffuse heating also reduces the initial star formation rate (SFR), slowing the conversation of gas into stars. We therefore conclude that the interstellar environment plays an important role in the GMC evolution. Our clouds live between 0 and 20 Myr with a high infant mortality (t' < 3 Myr) due to cloud mergers and star formation. Other properties, including distributions of mass, size, and surface density, agree well with observations. Collisions between our clouds are common, occurring at a rate of ∼ 1/4 of the orbital period. It is not clear whether such collisions trigger or suppress star formation at our current resolution. Our SFR is a factor of 10 higher than observations in local galaxies. This is likely due to the absence of localized feedback in our models.

Aggregate formation in 3D turbulent-like flows

NARCIS (Netherlands)

Dominguez, A.; Aartrijk, van M.; Castello, Del L.; Clercx, H.J.H.; Geurts, B.; Clercx, H

2006-01-01

Aggregate formation is an important process in industrial and environ mental turbulent flows. Two examples in the environmental area, where turbulent aggregate formation takes place, are raindrop formation in clouds and Marine Snow (aggregate) formation in the upper layer in the oceans. The

Chlorination and chloramines formation

International Nuclear Information System (INIS)

Yee, Lim Fang; Mohd Pauzi Abdullah; Sadia Ata; Abbas Abdullah; Basar IShak; Khairul Nidzham

2008-01-01

Chlorination is the most important method of disinfection in Malaysia which aims at ensuring an acceptable and safe drinking water quality. The dosing of chlorine to surface water containing ammonia and nitrogen compounds may form chloramines in the treated water. During this reaction, inorganic and organic chloramines are formed. The recommended maximum acceptable concentration (MAC) for chloramines in drinking water is 3000 μg/L. The production of monochloramine, dichloramine and trichloramine is highly dependent upon pH, contact time and the chlorine to ammonia molar ratio. The purpose of this study is to examine the formation of chloramines that occur upon the chlorination during the treatment process. Chloramines were determined using the N,N-diethyl-p-phenylenediamine (DPD) colorimetric method. The influences of ammonia, pH and chlorine dosage on the chloramines formation were also studied. This paper presents a modeling approach based on regression analysis which is designed to estimate the formation of chloramines. The correlation between the concentration of chloramines and the ammonia, pH and chlorine dosage was examined. In all cases, the quantity of chloramines formed depended linearly upon the amount of chlorine dosage. On the basis of this study it reveals that the concentration of chloramines is a function of chlorine dosage and the ammonia concentration to the chlorination process. PH seems to not significantly affect the formation of chloramines. (author)

Flowchart-format emergency operating procedures-strengths and weaknesses

International Nuclear Information System (INIS)

Barnes, V.E.; Bongarra, J.P. Jr.

1989-01-01

An increasing number of nuclear power plant licensees are converting their text-format emergency operating procedures (EOPs) to flowcharts. Findings of a recent study of the flowchart-format EOPs indicate that the flowchart format appears to solve several significant usability problems associated with text-format EOPs, but also introduces other types of usability concerns. This paper discusses some of the strengths and weaknesses of the flowchart format for presenting EOPs

Formation Number Of Laminar Vortex Rings. Numerical Simulations

International Nuclear Information System (INIS)

Rosenfeld, M.; Rambod, E.; Gharib, M.

1998-01-01

The formation time scale of axisymmetric vortex rings is studied numerically for relatively long discharge times. Experimental findings on the existence and universality of a formation time scale, referred to as the formation number, are confirmed. The formation number is indicative of the time a vortex ring acquires its maximal circulation. For vortex rings generated by impulsive motion of a piston, the formation number was found experimentally to be approximately 4. Numerical extension of the experimental study to thick shear layers indicates that the scaled circulation of the pinched-off vortex is relatively insensitive of the details of the formation process, such as the velocity program, velocity profile or vortex generator geometry. In contrast, the formation number does depend on the velocity profile

Portable File Format (PFF) specifications

Energy Technology Data Exchange (ETDEWEB)

Dolan, Daniel H. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

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.

Satellite Formation Control Using Atmospheric Drag

National Research Council Canada - National Science Library

Hajovsky, Blake B

2007-01-01

This study investigates the use of a linear quadratic terminal controller to reconfigure satellite formations using atmospheric drag actuated control while minimizing the loss of energy of the formation...

Formation and elution of toxic compounds from sterilized medical products: toxic compound formation from irradiated products

International Nuclear Information System (INIS)

Shintani, Hideharu

1996-01-01

No formation of MDA was observed in chain-extended thermoplastic polyurethane (PU) when sterilized by autoclave or γ-ray irradiation. No formation of MDA was observed in nonchain-extended thermoplastic PU when sterilized by γ-ray irradiation. Less than 1 ppm MDA was produced in nonchain-extended thermoplastic PU sterilized by autoclave sterilization. Autoclave sterilization did not produce MDA in thermosetting PU potting material. MDA formation in potting material was promoted by γ-irradiation and increased with increasing irradiation at a quadratic equation of regression. MDA formation at 100 kGy irradiation is a few ppm and < 1 ppm at 25kGy irradiation, therefore the potential risk to human recipients was not significant. The elution of compounds other than MDA from potting material was more problematic. Solvent extracts from potting material presented mutagenicity in the absence of metabolic activity. MDA presented mutagenicity in the presence of metabolic activity, therefore MDA was not the mutagenic trigger. The chemical and biological characteristics of the specific mutagens required to identify in a further study. Negative promotion of MDA formation and a less presence of mutagen in autoclave sterilized potting material indicated that autoclave sterilization was preferable. (Author)

Formation and behaviour of organic iodine

International Nuclear Information System (INIS)

Zilliacus, R.; Koukkar, P.; Karjunen, T.; Sjoevall, H.

2002-01-01

The report presents experimental studies on the formation of organic iodine in severe reactor accidents. The analyses were performed to evaluate the amount of alkaline chemical needed for effective pH control of containment water during the accidents. The formation of organic iodine in solutions used in the filtered venting system and the absorption of iodine compounds in the solutions were studied. Experiments for the formation of organic iodine on painted surfaces were also performed. (au)

Cumulative approaches to track formation under swift heavy ion (SHI) irradiation: Phenomenological correlation with formation energies of Frenkel pairs

Energy Technology Data Exchange (ETDEWEB)

Crespillo, M.L., E-mail: mcrespil@utk.edu [Centro de Microanálisis de Materiales, CMAM-UAM, Cantoblanco, Madrid 28049 (Spain); Department of Materials Science & Engineering, University of Tennessee, Knoxville, TN 37996 (United States); Agulló-López, F., E-mail: fal@uam.es [Centro de Microanálisis de Materiales, CMAM-UAM, Cantoblanco, Madrid 28049 (Spain); Zucchiatti, A. [Centro de Microanálisis de Materiales, CMAM-UAM, Cantoblanco, Madrid 28049 (Spain)

2017-03-01

Highlights: • Extensive survey formation energies Frenkel pairs and electronic stopping thresholds. • Correlation: track formation thresholds and the energies for Frenkel pair formation. • Formation energies Frenkel pairs discussed in relation to the cumulative mechanisms. • Amorphous track formation mechanisms: defect accumulation models versus melting. • Advantages cumulative models to deal with new hot topics: nuclear-electronic synergy. - Abstract: An extensive survey for the formation energies of Frenkel pairs, as representative candidates for radiation-induced point defects, is presented and discussed in relation to the cumulative mechanisms (CM) of track formation in dielectric materials under swift heavy ion (SHI) irradiation. These mechanisms rely on the generation and accumulation of point defects during irradiation followed by collapse of the lattice once a threshold defect concentration is reached. The physical basis of those approaches has been discussed by Fecht as a defect-assisted transition to an amorphous phase. Although a first quantitative analysis of the CM model was previously performed for LiNbO{sub 3} crystals, we have, here, adopted a broader phenomenological approach. It explores the correlation between track formation thresholds and the energies for Frenkel pair formation for a broad range of materials. It is concluded that the threshold stopping powers can be roughly scaled with the energies required to generate a critical Frenkel pair concentration in the order of a few percent of the total atomic content. Finally, a comparison with the predictions of the thermal spike model is discussed within the analytical Szenes approximation.

Hyper-massive cloud, shock and stellar formation efficiency

International Nuclear Information System (INIS)

Louvet, Fabien

2014-01-01

O and B types stars are of paramount importance in the energy budget of galaxies and play a crucial role enriching the interstellar medium. However, their formation, unlike that of solar-type stars, is still subject to debate, if not an enigma. The earliest stages of massive star formation and the formation of their parent cloud are still crucial astrophysical questions that drew a lot of attention in the community, both from the theoretical and observational perspective, during the last decade. It has been proposed that massive stars are born in massive dense cores that form through very dynamic processes, such as converging flows of gas. During my PhD, I conducted a thorough study of the formation of dense cores and massive stars in the W43-MM1 supermassive structure, located at 6 kpc from the sun. At first, I showed a direct correlation between the star formation efficiency and the volume gas density of molecular clouds, in contrast with scenarios suggested by previous studies. Indeed, the spatial distribution and mass function of the massive dense cores currently forming in W43-MM1 suggests that this supermassive filament is undergoing a star formation burst, increasing as one approaches its center. I compared these observational results with the most recent numerical and analytical models of star formation. This comparison not only provides new constraints on the formation of supermassive filaments, but also suggests that understanding star formation in high density, extreme ridges requires a detailed portrait of the structure of these exceptional objects. Second, having shown that the formation of massive stars depends strongly on the properties of the ridges where they form, I studied the formation processes of these filaments, thanks of the characterization of their global dynamics. Specifically, I used a tracer of shocks (SiO molecule) to disentangle the feedback of local star formation processes (bipolar jets and outflows) from shocks tracing the pristine

Autonomous formation flight of helicopters: Model predictive control approach

Science.gov (United States)

Chung, Hoam

Formation flight is the primary movement technique for teams of helicopters. However, the potential for accidents is greatly increased when helicopter teams are required to fly in tight formations and under harsh conditions. This dissertation proposes that the automation of helicopter formations is a realistic solution capable of alleviating risks. Helicopter formation flight operations in battlefield situations are highly dynamic and dangerous, and, therefore, we maintain that both a high-level formation management system and a distributed coordinated control algorithm should be implemented to help ensure safe formations. The starting point for safe autonomous formation flights is to design a distributed control law attenuating external disturbances coming into a formation, so that each vehicle can safely maintain sufficient clearance between it and all other vehicles. While conventional methods are limited to homogeneous formations, our decentralized model predictive control (MPC) approach allows for heterogeneity in a formation. In order to avoid the conservative nature inherent in distributed MPC algorithms, we begin by designing a stable MPC for individual vehicles, and then introducing carefully designed inter-agent coupling terms in a performance index. Thus the proposed algorithm works in a decentralized manner, and can be applied to the problem of helicopter formations comprised of heterogenous vehicles. Individual vehicles in a team may be confronted by various emerging situations that will require the capability for in-flight reconfiguration. We propose the concept of a formation manager to manage separation, join, and synchronization of flight course changes. The formation manager accepts an operator's commands, information from neighboring vehicles, and its own vehicle states. Inside the formation manager, there are multiple modes and complex mode switchings represented as a finite state machine (FSM). Based on the current mode and collected

Heating tar sands formations to visbreaking temperatures

Science.gov (United States)

Karanikas, John Michael [Houston, TX; Colmenares, Tulio Rafael [Houston, TX; Zhang, Etuan [Houston, TX; Marino, Marian [Houston, TX; Roes, Augustinus Wilhelmus Maria [Houston, TX; Ryan, Robert Charles [Houston, TX; Beer, Gary Lee [Houston, TX; Dombrowski, Robert James [Houston, TX; Jaiswal, Namit [Houston, TX

2009-12-22

Methods for treating a tar sands formation are described herein. Methods may include heating at least a section of a hydrocarbon layer in the formation from a plurality of heaters located in the formation. The heat may be controlled so that at least a majority of the section reaches an average temperature of between 200.degree. C. and 240.degree. C., which results in visbreaking of at least some hydrocarbons in the section. At least some visbroken hydrocarbon fluids may be produced from the formation.

Interoperability format translation and transformation between IFC architectural design file and simulation file formats

Science.gov (United States)

Chao, Tian-Jy; Kim, Younghun

2015-01-06

Automatically translating a building architecture file format (Industry Foundation Class) to a simulation file, in one aspect, may extract data and metadata used by a target simulation tool from a building architecture file. Interoperability data objects may be created and the extracted data is stored in the interoperability data objects. A model translation procedure may be prepared to identify a mapping from a Model View Definition to a translation and transformation function. The extracted data may be transformed using the data stored in the interoperability data objects, an input Model View Definition template, and the translation and transformation function to convert the extracted data to correct geometric values needed for a target simulation file format used by the target simulation tool. The simulation file in the target simulation file format may be generated.

Star formation in the multiverse

International Nuclear Information System (INIS)

Bousso, Raphael; Leichenauer, Stefan

2009-01-01

We develop a simple semianalytic model of the star formation rate as a function of time. We estimate the star formation rate for a wide range of values of the cosmological constant, spatial curvature, and primordial density contrast. Our model can predict such parameters in the multiverse, if the underlying theory landscape and the cosmological measure are known.

Mantle dynamics following supercontinent formation

Science.gov (United States)

Heron, Philip J.

This thesis presents mantle convection numerical simulations of supercontinent formation. Approximately 300 million years ago, through the large-scale subduction of oceanic sea floor, continental material amalgamated to form the supercontinent Pangea. For 100 million years after its formation, Pangea remained relatively stationary, and subduction of oceanic material featured on its margins. The present-day location of the continents is due to the rifting apart of Pangea, with supercontinent dispersal being characterized by increased volcanic activity linked to the generation of deep mantle plumes. The work presented here investigates the thermal evolution of mantle dynamics (e.g., mantle temperatures and sub-continental plumes) following the formation of a supercontinent. Specifically, continental insulation and continental margin subduction are analyzed. Continental material, as compared to oceanic material, inhibits heat flow from the mantle. Previous numerical simulations have shown that the formation of a stationary supercontinent would elevate sub-continental mantle temperatures due to the effect of continental insulation, leading to the break-up of the continent. By modelling a vigorously convecting mantle that features thermally and mechanically distinct continental and oceanic plates, this study shows the effect of continental insulation on the mantle to be minimal. However, the formation of a supercontinent results in sub-continental plume formation due to the re-positioning of subduction zones to the margins of the continent. Accordingly, it is demonstrated that continental insulation is not a significant factor in producing sub-supercontinent plumes but that subduction patterns control the location and timing of upwelling formation. A theme throughout the thesis is an inquiry into why geodynamic studies would produce different results. Mantle viscosity, Rayleigh number, continental size, continental insulation, and oceanic plate boundary evolution are

The three phases of galaxy formation

Science.gov (United States)

Clauwens, Bart; Schaye, Joop; Franx, Marijn; Bower, Richard G.

2018-05-01

We investigate the origin of the Hubble sequence by analysing the evolution of the kinematic morphologies of central galaxies in the EAGLE cosmological simulation. By separating each galaxy into disc and spheroidal stellar components and tracing their evolution along the merger tree, we find that the morphology of galaxies follows a common evolutionary trend. We distinguish three phases of galaxy formation. These phases are determined primarily by mass, rather than redshift. For M* ≲ 109.5M⊙ galaxies grow in a disorganised way, resulting in a morphology that is dominated by random stellar motions. This phase is dominated by in-situ star formation, partly triggered by mergers. In the mass range 109.5M⊙ ≲ M* ≲ 1010.5M⊙ galaxies evolve towards a disc-dominated morphology, driven by in-situ star formation. The central spheroid (i.e. the bulge) at z = 0 consists mostly of stars that formed in-situ, yet the formation of the bulge is to a large degree associated with mergers. Finally, at M* ≳ 1010.5M⊙ growth through in-situ star formation slows down considerably and galaxies transform towards a more spheroidal morphology. This transformation is driven more by the buildup of spheroids than by the destruction of discs. Spheroid formation in these galaxies happens mostly by accretion at large radii of stars formed ex-situ (i.e. the halo rather than the bulge).

Zircon U-Pb geochronology, Sm-Nd and Pb-Pb isotope systematics of Ediacaran post-collisional high-silica Acampamento Velho volcanism at the Tupanci area, NW of the Sul-Rio-Grandense Shield, Brazil

Energy Technology Data Exchange (ETDEWEB)

Sommer, Carlos Augusto; Leitzke, Felipe Padilha; Lima, Evandro Fernandes de; Barreto, Carla Joana Santos; Matté, Vinicius; Philipp, Ruy Paulo; Conceição, Rommulo Vieira, E-mail: casommer@sinos.net, E-mail: eflgeologo@gmail.com, E-mail: ruy.philipp@ufrgs.br, E-mail: rommulo.conceicao@ufrgs.br [Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS (Brazil). Instituto de Geociências; Lafon, Jean Michel, E-mail: lafonjm@ufpa.br [Universidade Federal do Pará (UFPA), Belém, PA (Brazil). Laboratório de Geologia Isotópica; Basei, Miguel Ângelo Stipp, E-mail: baseimas@usp.br [Universidade de São Paulo (CPGeo/IGc/USP), São Paulo, SP (Brazil)

2017-10-15

We present new U-Pb zircon ages and Sm-Nd-Pb isotopic data for volcanic and hypabyssal acid rocks from the northernmost exposure of the Acampamento Velho Formation in the NW portion of the Sul-Rio-Grandense Shield, Brazil. The first volcanic episode, grouped in the high-Ti rhyolites from the Tupanci hill, shows age of 579 ± 5.6 Ma, which is in agreement with the post-collisional Acampamento Velho Formation volcanism in the Bom Jardim Group of the Camaquã Basin. A poorly constrained age of 558+/- 39Ma was obtained for rhyolites from the low-Ti group at the Picados Hill, which may indicate a younger acid volcanism, or a greater time span for the volcanism of the Acampamento Velho Formation in southernmost Brazil. Regarding magmatic sources, Sm/Nd isotopic data coupled to Pb isotopes and a review of trace element geochemistry indicate different amounts of Paleoproterozoic (Dom Feliciano, Pinheiro Machado Suite) to Neoproterozoic (Rio Vacacaí terrane) lower crust melting. Our data, coupled with literature data, contribute to a better understanding of the stratigraphic evolution for the Neoproterozoic post-collisional volcanic successions of the Camaquã Basin in the Sul-Rio-Grandense Shield. (author)

Hard sludge formation in modern steam generators of nuclear power plants. Formation, risks and mitigation

International Nuclear Information System (INIS)

Strohmer, F.

2014-01-01

In recent years modern steam generators with triangular pitch tube bundle geometry have experienced damage caused by hard sludge formation on top of the tube sheet and denting. The effect can lead to a limitation of the modern steam generators’ lifetime. The current publication shows reasons for the generation of hard sludge formation. Moreover, it describes the risk arising from hard sludge formation for the concerned steam generators and the mitigation of the problem. The main factors contributing to the formation of hard sludge are: the amount of corrosion product ingress into the steam generators, hard sludge formation favouring impurities and, skipped maintenance applications during outages. The main damaging mechanism of denting that can arise under certain secondary side conditions from hard sludge is explained. For steam generator tube denting, aggressive, oxidizing conditions have to be established in crevices beneath the hard sludge piles. Severely dented tubes are sensitive toward outer diameter stress corrosion cracking (ODSCC). The denting and ODSCC mechanism is explained. In addition, a proactive long-term maintenance strategy to avoid the formation of hard sludge piles will be shown. The strategy is based on a reduction of the corrosion product ingress into the steam generator's secondary side, and on the regular removal of deposits from the tube sheet and from the entire upper bundle area by latest mechanical cleaning methods. For hard deposits - formed either by silicates or long term hardened corrosion products, which, in the past, could not be removed by chemical or mechanical means - a new, simple, mechanical cleaning method is presented. This method can be used during the normal time frame of an outage and allows the restart of the unit with clean steam generator tube sheets. This mitigates the tendency to form hard sludge and denting in the long term. (author)

Muonium/muonic hydrogen formation in atomic hydrogen

Indian Academy of Sciences (India)

The muonium/muonic hydrogen atom formation in ± –H collisions is investigated, using a two-state approximation in a time dependent formalism. It is found that muonium cross-section results are similar to the cross-section results obtained for positronium formation in + –H collision. Muonic hydrogen atom formation ...

Formative assessment: a student perspective.

Science.gov (United States)

Hill, D A; Guinea, A I; McCarthy, W H

1994-09-01

An educator's view would be that formative assessment has an important role in the learning process. This study was carried out to obtain a student perspective of the place of formative assessment in the curriculum. Final-year medical students at Royal Prince Alfred Hospital took part in four teaching sessions, each structured to integrate teaching with assessment. Three assessment methods were used; the group objective structured clinical examination (G-OSCE), structured short answer (SSA) questions and a pre/post-test multiple choice questionnaire (MCQ). Teaching sessions were conducted on the subject areas of traumatology, the 'acute abdomen', arterial disorders and cancer. Fifty-five students, representing 83% of those who took part in the programme, responded to a questionnaire where they were asked to rate (on a 5-point Likert scale) their response to general questions about formative assessment and 13 specific questions concerning the comparative value of the three assessment modalities. Eighty-nine per cent of respondents felt that formative assessment should be incorporated into the teaching process. The SSA assessment was regarded as the preferred modality to reinforce previous teaching and test problem-solving skills. The MCQ was the least favoured assessment method. The effect size variable between the total scores for the SSA and MCQ was 0.64. The variable between G-OSCE and SSA/MCQ was 0.26 and 0.33 respectively. Formative assessment is a potentially powerful method to direct learning behaviour. Students should have input into the methods used.

Secretory processes involved in the formation of milk

International Nuclear Information System (INIS)

Knutsson, P.G.

1976-01-01

Current knowledge on milk formation is reviewed. Emphasis is given to sites of formation of protein, fat and lactose, and transfer of these compounds into the alveolar lumen. Further, the formation of the water phase of milk is thoroughly discussed, and evidence presented that milk formation includes both secretory and re-absorptive processes as well as diffusion. A short presentation of colostrum formation is included. Neither biochemical processes involved in synthesis of organic compounds nor mammary gland endocrinology are discussed. (author)

Increased formate overflow is a hallmark of oxidative cancer.

Science.gov (United States)

Meiser, Johannes; Schuster, Anne; Pietzke, Matthias; Vande Voorde, Johan; Athineos, Dimitris; Oizel, Kristell; Burgos-Barragan, Guillermo; Wit, Niek; Dhayade, Sandeep; Morton, Jennifer P; Dornier, Emmanuel; Sumpton, David; Mackay, Gillian M; Blyth, Karen; Patel, Ketan J; Niclou, Simone P; Vazquez, Alexei

2018-04-10

Formate overflow coupled to mitochondrial oxidative metabolism\\ has been observed in cancer cell lines, but whether that takes place in the tumor microenvironment is not known. Here we report the observation of serine catabolism to formate in normal murine tissues, with a relative rate correlating with serine levels and the tissue oxidative state. Yet, serine catabolism to formate is increased in the transformed tissue of in vivo models of intestinal adenomas and mammary carcinomas. The increased serine catabolism to formate is associated with increased serum formate levels. Finally, we show that inhibition of formate production by genetic interference reduces cancer cell invasion and this phenotype can be rescued by exogenous formate. We conclude that increased formate overflow is a hallmark of oxidative cancers and that high formate levels promote invasion via a yet unknown mechanism.

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…

Planet Formation

Science.gov (United States)

Podolak, Morris

2018-04-01

Modern observational techniques are still not powerful enough to directly view planet formation, and so it is necessary to rely on theory. However, observations do give two important clues to the formation process. The first is that the most primitive form of material in interstellar space exists as a dilute gas. Some of this gas is unstable against gravitational collapse, and begins to contract. Because the angular momentum of the gas is not zero, it contracts along the spin axis, but remains extended in the plane perpendicular to that axis, so that a disk is formed. Viscous processes in the disk carry most of the mass into the center where a star eventually forms. In the process, almost as a by-product, a planetary system is formed as well. The second clue is the time required. Young stars are indeed observed to have gas disks, composed mostly of hydrogen and helium, surrounding them, and observations tell us that these disks dissipate after about 5 to 10 million years. If planets like Jupiter and Saturn, which are very rich in hydrogen and helium, are to form in such a disk, they must accrete their gas within 5 million years of the time of the formation of the disk. Any formation scenario one proposes must produce Jupiter in that time, although the terrestrial planets, which don't contain significant amounts of hydrogen and helium, could have taken longer to build. Modern estimates for the formation time of the Earth are of the order of 100 million years. To date there are two main candidate theories for producing Jupiter-like planets. The core accretion (CA) scenario supposes that any solid materials in the disk slowly coagulate into protoplanetary cores with progressively larger masses. If the core remains small enough it won't have a strong enough gravitational force to attract gas from the surrounding disk, and the result will be a terrestrial planet. If the core grows large enough (of the order of ten Earth masses), and the disk has not yet dissipated, then

Exploring the value of usability feedback formats

DEFF Research Database (Denmark)

Nørgaard, Mie; Hornbæk, Kasper Anders Søren

2009-01-01

The format used to present feedback from usability evaluations to developers affects whether problems are understood, accepted, and fixed. Yet, little research has investigated which formats are the most effective. We describe an explorative study where three developers assess 40 usability findings...... presented using five feedback formats. Our usability findings comprise 35 problems and 5 positive comments. Data suggest that feedback serves multiple purposes. Initially, feedback must convince developers about the relevance of a problem and convey an understanding of this. Feedback must next be easy...... working with the feedback to address the usability problems, there were no significant differences among the developers' ratings of the value of the different formats. This suggests that all of the formats may serve equally well as reminders in later stages of working with usability problems...

The role of the family in personality formation

Directory of Open Access Journals (Sweden)

Pylkov E.A.

2018-04-01

Full Text Available the article reveals such actual components of modern society as family, personality formation in the family, formation of the self-concept, life-purpose orientations of modern youth. One of the key moments in personality formation is movement, action. Formation involves personality development, both physically and spiritually from the very beginning of a person's life.

Academic Formation and Formative Research Integration Management for the Culmination of Studies Process in Higher Education

Directory of Open Access Journals (Sweden)

Lorna Cruz Rizo

2016-12-01

Full Text Available Given the up- dated international difficulties in the completion of studies process, theoretical and practical studies developed in this field are surprisingly scarce. Particularly, there has been a limited quantity of students that support their diploma thesis after completing their credits at the School of Languages and Linguistics at the University of Guayaquil. Consequently, this paper faces the problem of the insufficiencies in the culmination of studies process in relation to the management of the academic and scientific formation. Thus, the objective is: to improve the completion of studies or degree- obtaining processes in university education, through the implementation of a praxiological proposal of academic formation and formative research integration. Accordingly, the author´s experiences systematization is the methodology mainly used. The essential logic for the management of the academic formation and formative research integration was revealed as the main proposal, therefore this is the solution to the problem diagnosed. This is based on a curricular structure, in which each of the subjects was interrelated to each of the essential stages of the scientific research. As main results obtained, the students were able to solve real-life problems diagnosed at educative institutions, also they drew up the draft of their theses.

Planetesimal formation starts at the snow line

Science.gov (United States)

Drążkowska, J.; Alibert, Y.

2017-12-01

Context. The formation stage of planetesimals represents a major gap in our understanding of the planet formation process. Late-stage planet accretion models typically make arbitrary assumptions about planetesimal and pebble distribution, while dust evolution models predict that planetesimal formation is only possible at some orbital distances. Aims: We wish to test the importance of the water snow line in triggering the formation of the first planetesimals during the gas-rich phase of a protoplanetary disk, when cores of giant planets have to form. Methods: We connected prescriptions for gas disk evolution, dust growth and fragmentation, water ice evaporation and recondensation, the transport of both solids and water vapor, and planetesimal formation via streaming instability into a single one-dimensional model for protoplanetary disk evolution. Results: We find that processes taking place around the snow line facilitate planetesimal formation in two ways. First, because the sticking properties between wet and dry aggregates change, a "traffic jam" inside of the snow line slows the fall of solids onto the star. Second, ice evaporation and outward diffusion of water followed by its recondensation increases the abundance of icy pebbles that trigger planetesimal formation via streaming instability just outside of the snow line. Conclusions: Planetesimal formation is hindered by growth barriers and radial drift and thus requires particular conditions to take place. The snow line is a favorable location where planetesimal formation is possible for a wide range of conditions, but not in every protoplanetary disk model, however. This process is particularly promoted in large cool disks with low intrinsic turbulence and an increased initial dust-to-gas ratio. The movie attached to Fig. 3 is only available at http://www.aanda.org

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.

Star formation in active galaxies and quasars

International Nuclear Information System (INIS)

Heckman, T.M.

1987-01-01

I review the observational evidence for a causal or statistical link between star formation and active galactic nuclei. The chief difficulty is in quantitatively ascertaining the star formation rate in active galaxies: most of the readily observable manifestations of star formation superficially resemble those of an active nucleus. Careful multi-wavelength spatially-resolved observations demonstrate that many Seyfert galaxies are undergoing star formation. Our survey of CO emission from Seyferts (interpreted in conjunction IRAS data) suggests that type 2 Seyferts have unusually high rates of star formation, but type 1 Seyferts do not. Recent work also suggests that many powerful radio galaxies may be actively forming stars: radio galaxies with strong emission-lines often have blue colors and strong far-infrared emission. Determining the star formation rate in the host galaxies of quasars is especially difficult. Multi-color imaging and long-slit spectroscopy suggests that many of the host galaxies of radio-loud quasars are blue and a cold interstellar medium has been detected in some quasar hosts

Networks for Autonomous Formation Flying Satellite Systems

Science.gov (United States)

Knoblock, Eric J.; Konangi, Vijay K.; Wallett, Thomas M.; Bhasin, Kul B.

2001-01-01

The performance of three communications networks to support autonomous multi-spacecraft formation flying systems is presented. All systems are comprised of a ten-satellite formation arranged in a star topology, with one of the satellites designated as the central or "mother ship." All data is routed through the mother ship to the terrestrial network. The first system uses a TCP/lP over ATM protocol architecture within the formation the second system uses the IEEE 802.11 protocol architecture within the formation and the last system uses both of the previous architectures with a constellation of geosynchronous satellites serving as an intermediate point-of-contact between the formation and the terrestrial network. The simulations consist of file transfers using either the File Transfer Protocol (FTP) or the Simple Automatic File Exchange (SAFE) Protocol. The results compare the IF queuing delay, and IP processing delay at the mother ship as well as application-level round-trip time for both systems, In all cases, using IEEE 802.11 within the formation yields less delay. Also, the throughput exhibited by SAFE is better than FTP.

Radiation pressure in super star cluster formation

Science.gov (United States)

Tsang, Benny T.-H.; Milosavljević, Miloš

2018-05-01

The physics of star formation at its extreme, in the nuclei of the densest and the most massive star clusters in the universe—potential massive black hole nurseries—has for decades eluded scrutiny. Spectroscopy of these systems has been scarce, whereas theoretical arguments suggest that radiation pressure on dust grains somehow inhibits star formation. Here, we harness an accelerated Monte Carlo radiation transport scheme to report a radiation hydrodynamical simulation of super star cluster formation in turbulent clouds. We find that radiation pressure reduces the global star formation efficiency by 30-35%, and the star formation rate by 15-50%, both relative to a radiation-free control run. Overall, radiation pressure does not terminate the gas supply for star formation and the final stellar mass of the most massive cluster is ˜1.3 × 106 M⊙. The limited impact as compared to in idealized theoretical models is attributed to a radiation-matter anti-correlation in the supersonically turbulent, gravitationally collapsing medium. In isolated regions outside massive clusters, where the gas distribution is less disturbed, radiation pressure is more effective in limiting star formation. The resulting stellar density at the cluster core is ≥108 M⊙ pc-3, with stellar velocity dispersion ≳ 70 km s-1. We conclude that the super star cluster nucleus is propitious to the formation of very massive stars via dynamical core collapse and stellar merging. We speculate that the very massive star may avoid the claimed catastrophic mass loss by continuing to accrete dense gas condensing from a gravitationally-confined ionized phase.

JOYFOR: A program for transformation of NJOY results in MATXS-format to the MITRA input format

International Nuclear Information System (INIS)

Krieg, B.; Broeders, I.

1987-02-01

The program JOYFOR is the connection between the output of the group constant calculation code NJOY in MATXS-format and the testing and formatting program MITRA. Resonance selfshielding factors as well as transfermatrices for elastic and inelastic scattering and for (n,2n)- and (n,3n)-processes, normalized corresponding to the conventions of MITRA, are calculated by JOYFOR from the NJOY results and are written in MIGROS-format on an external file and on the standard output unit. Also the group cross-sections for infinite dilution, the 1/v-values and the fission spectrum are written out in the same format as in MIGROS. KERMA-factors are handled by JOYFOR in the same way as group cross-sections. The output data of JOYFOR may be tested by MITRA and transformed into input for the GRUBA management program GRUMA. The present version of JOYFOR handles group constants for neutron reactions only. Extension of the program to photon reactions is being planned. (orig.) [de

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.

Fusomorphogenesis: cell fusion in organ formation.

Science.gov (United States)

Shemer, G; Podbilewicz, B

2000-05-01

Cell fusion is a universal process that occurs during fertilization and in the formation of organs such as muscles, placenta, and bones. Very little is known about the molecular and cellular mechanisms of cell fusion during pattern formation. Here we review the dynamic anatomy of all cell fusions during embryonic and postembryonic development in an organism. Nearly all the cell fates and cell lineages are invariant in the nematode C. elegans and one third of the cells that are born fuse to form 44 syncytia in a reproducible and stereotyped way. To explain the function of cell fusion in organ formation we propose the fusomorphogenetic model as a simple cellular mechanism to efficiently redistribute membranes using a combination of cell fusion and polarized membrane recycling during morphogenesis. Thus, regulated intercellular and intracellular membrane fusion processes may drive elongation of the embryo as well as postembryonic organ formation in C. elegans. Finally, we use the fusomorphogenetic hypothesis to explain the role of cell fusion in the formation of organs like muscles, bones, and placenta in mammals and other species and to speculate on how the intracellular machinery that drive fusomorphogenesis may have evolved.

Transient Exciplex Formation Electron Transfer Mechanism

Directory of Open Access Journals (Sweden)

Michael G. Kuzmin

2011-01-01

Full Text Available Transient exciplex formation mechanism of excited-state electron transfer reactions is analyzed in terms of experimental data on thermodynamics and kinetics of exciplex formation and decay. Experimental profiles of free energy, enthalpy, and entropy for transient exciplex formation and decay are considered for several electron transfer reactions in various solvents. Strong electronic coupling in contact pairs of reactants causes substantial decrease of activation energy relative to that for conventional long-range ET mechanism, especially for endergonic reactions, and provides the possibility for medium reorganization concatenated to gradual charge shift in contrast to conventional preliminary medium and reactants reorganization. Experimental criteria for transient exciplex formation (concatenated mechanism of excited-state electron transfer are considered. Available experimental data show that this mechanism dominates for endergonic ET reactions and provides a natural explanation for a lot of known paradoxes of ET reactions.

Towards the Rosetta Stone of planet formation

Directory of Open Access Journals (Sweden)

Schmidt T.O.B.

2011-02-01

Full Text Available Transiting exoplanets (TEPs observed just ~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 goal of which is to find and then characterise TEPs in very young open clusters.

Review of nutrition labeling formats.

Science.gov (United States)

Geiger, C J; Wyse, B W; Parent, C R; Hansen, R G

1991-07-01

This article examines nutrition labeling history as well as the findings of nine research studies of nutrition labeling formats. Nutrition labeling regulations were announced in 1973 and have been periodically amended since then. In response to requests from consumers and health care professionals for revision of the labeling system, the Food and Drug Administration initiated a three-phase plan for reform of nutrition labeling in 1990. President Bush signed the Nutrition Labeling and Education Act in November 1990. Literature analysis revealed that only nine studies with an experimental design have focused on nutrition labeling since 1971. Four were conducted before 1975, which was the year that nutrition labeling was officially implemented, two were conducted in 1980, and three were conducted after 1986. Only two of the nine studies supported the traditional label format mandated by the Code of Federal Regulations, and one study partially supported it. Four of the nine studies that evaluated graphic presentations of nutrition information found that consumer comprehension of nutrition information was improved with a graphic format for nutrition labeling: three studies supported the use of bar graphs and one study supported the use of a pie chart. Full disclosure (ie, complete nutrient and ingredient labeling) was preferred by consumers in two of the three studies that examined this variable. The third study supported three types of information disclosure dependent upon socioeconomic class. In those studies that tested graphics, a bar graph format was significantly preferred and showed better consumer comprehension than the traditional format.

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....

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.

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

Computer-based feedback in formative assessment

NARCIS (Netherlands)

van der Kleij, Fabienne

2013-01-01

Formative assessment concerns any assessment that provides feedback that is intended to support learning and can be used by teachers and/or students. Computers could offer a solution to overcoming obstacles encountered in implementing formative assessment. For example, computer-based assessments

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

Results of a downhole formation microscanner study in a Juro-Triassic-aged sedimentary deposit (Passaic Formation)

International Nuclear Information System (INIS)

Fischer, J.A.; Fischer, J.J.; Bullwinkel, R.J.

1994-01-01

Studies to determine the structural and geohydrological properties of the Passaic Formation were performed at two sites. Both sites are located in northeastern New Jersey, within the Juro-Triassic-aged Newark Basin. The Passaic Formation rocks are described in the literature as a reddish brown, thin to massively bedded, sedimentary deposit with lithology ranging from claystone through conglomerate. A fractured open-quotes layer cakeclose quotes model has been proposed (and is generally accepted) to describe the prevailing geohydrological conditions. The Formation MicroScanner tool was used in four wells drilled for these projects (two at each site). In addition to this microresistivity tool, a suite of other oil field geophysical tools (Gamma, Induction, Dipmeter, Temperature, and Neutron probes) were also utilized. The data collected with the Formation MicroScanner were correlated with detailed logs and the continuous core retrieved from three of the wells. Pump test data was also obtained at both sites. The geophysical data obtained at both sites allowed the direct identification of fractures and their orientation in relation to bedding. Fracture and bedding aperture size and orientation were measured. The results, as presented in this paper, show a high degree of inhomogeneity at both sites rather than the conventional layer cake model. For appropriate site analyses it was necessary to significantly refine the previously assumed Passaic Formation geohydrological and structural model. 14 refs., 4 figs

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

Biostratigraphy of the Gurpi Formation in Zagros Basin, Iran

Directory of Open Access Journals (Sweden)

Abbas Sadeghi

2015-09-01

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

Right timing in formative program evaluation.

Science.gov (United States)

Hall, Jori; Freeman, Melissa; Roulston, Kathy

2014-08-01

Since many educational researchers and program developers have limited knowledge of formative evaluation, formative data may be underutilized during the development and implementation of an educational program. The purpose of this article is to explain how participatory, responsive, educative, and qualitative approaches to formative evaluation can facilitate a partnership between evaluators and educational researchers and program managers to generate data useful to inform program implementation and improvement. This partnership is critical, we argue, because it enables an awareness of when to take appropriate action to ensure successful educational programs or "kairos". To illustrate, we use examples from our own evaluation work to highlight how formative evaluation may facilitate opportune moments to (1) define the substance and purpose of a program, (2) develop understanding and awareness of the cultural interpretations of program participants, and (3) show the relevance of stakeholder experiences to program goals. Copyright © 2014 Elsevier Ltd. All rights reserved.

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.

Network Configuration Analysis for Formation Flying Satellites

Science.gov (United States)

Knoblock, Eric J.; Wallett, Thomas M.; Konangi, Vijay K.; Bhasin, Kul B.

2001-01-01

The performance of two networks to support autonomous multi-spacecraft formation flying systems is presented. Both systems are comprised of a ten-satellite formation, with one of the satellites designated as the central or 'mother ship.' All data is routed through the mother ship to the terrestrial network. The first system uses a TCP/EP over ATM protocol architecture within the formation, and the second system uses the IEEE 802.11 protocol architecture within the formation. The simulations consist of file transfers using either the File Transfer Protocol (FTP) or the Simple Automatic File Exchange (SAFE) Protocol. The results compare the IP queuing delay, IP queue size and IP processing delay at the mother ship as well as end-to-end delay for both systems. In all cases, using IEEE 802.11 within the formation yields less delay. Also, the throughput exhibited by SAFE is better than FTP.

Renewable Formate from C-H Bond Formation with CO2: Using Iron Carbonyl Clusters as Electrocatalysts.

Science.gov (United States)

Loewen, Natalia D; Neelakantan, Taruna V; Berben, Louise A

2017-09-19

As a society, we are heavily dependent on nonrenewable petroleum-derived fuels and chemical feedstocks. Rapid depletion of these resources and the increasingly evident negative effects of excess atmospheric CO 2 drive our efforts to discover ways of converting excess CO 2 into energy dense chemical fuels through selective C-H bond formation and using renewable energy sources to supply electrons. In this way, a carbon-neutral fuel economy might be realized. To develop a molecular or heterogeneous catalyst for C-H bond formation with CO 2 requires a fundamental understanding of how to generate metal hydrides that selectively donate H - to CO 2 , rather than recombining with H + to liberate H 2 . Our work with a unique series of water-soluble and -stable, low-valent iron electrocatalysts offers mechanistic and thermochemical insights into formate production from CO 2 . Of particular interest are the nitride- and carbide-containing clusters: [Fe 4 N(CO) 12 ] - and its derivatives and [Fe 4 C(CO) 12 ] 2- . In both aqueous and mixed solvent conditions, [Fe 4 N(CO) 12 ] - forms a reduced hydride intermediate, [H-Fe 4 N(CO) 12 ] - , through stepwise electron and proton transfers. This hydride selectively reacts with CO 2 and generates formate with >95% efficiency. The mechanism for this transformation is supported by crystallographic, cyclic voltammetry, and spectroelectrochemical (SEC) evidence. Furthermore, installation of a proton shuttle onto [Fe 4 N(CO) 12 ] - facilitates proton transfer to the active site, successfully intercepting the hydride intermediate before it reacts with CO 2 ; only H 2 is observed in this case. In contrast, isoelectronic [Fe 4 C(CO) 12 ] 2- features a concerted proton-electron transfer mechanism to form [H-Fe 4 C(CO) 12 ] 2- , which is selective for H 2 production even in the presence of CO 2 , in both aqueous and mixed solvent systems. Higher nuclearity clusters were also studied, and all are proton reduction electrocatalysts, but none

Formation of the First Stars and Blackholes

Science.gov (United States)

Yoshida, Naoki

2018-05-01

Cosmic reionization is thought to be initiated by the first generation of stars and blackholes. We review recent progress in theoretical studies of early structure formation. Cosmic structure formation is driven by gravitational instability of primeval density fluctuations left over from Big Bang. At early epochs, there are baryonic streaming motions with significant relative velocity with respect to dark matter. The formation of primordial gas clouds is typically delayed by the streaming motions, but then physical conditions for the so-called direct collapse blackhole formation are realized in proto-galactic halos. We present a promising model in which intermediate mass blackholes are formed as early as z = 30.

Simbol-X Formation Flight and Image Reconstruction

Science.gov (United States)

Civitani, M.; Djalal, S.; Le Duigou, J. M.; La Marle, O.; Chipaux, R.

2009-05-01

Simbol-X is the first operational mission relying on two satellites flying in formation. The dynamics of the telescope, due to the formation flight concept, raises a variety of problematic, like image reconstruction, that can be better evaluated via a simulation tools. We present here the first results obtained with Simulos, simulation tool aimed to study the relative spacecrafts navigation and the weight of the different parameters in image reconstruction and telescope performance evaluation. The simulation relies on attitude and formation flight sensors models, formation flight dynamics and control, mirror model and focal plane model, while the image reconstruction is based on the Line of Sight (LOS) concept.

An anti vimentin antibody promotes tube formation

DEFF Research Database (Denmark)

Jørgensen, Mathias Lindh; Møller, Carina Kjeldahl; Rasmussen, Lasse

2017-01-01

antibody technology, promotes tube formation of endothelial cells in a 2D matrigel assay. By binding vimentin, the antibody increases the tube formation by 21% after 5 hours of incubation. Addition of the antibody directly to cultured endothelial cells does not influence endothelial cell migration...... or proliferation. The enhanced tube formation can be seen for up to 10 hours where after the effect decreases. It is shown that the antibody-binding site is located on the coil 2 domain of vimentin. To our knowledge this is the first study that demonstrates an enhanced tube formation by binding vimentin in a 2D...

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.

SCIFIO: an extensible framework to support scientific image formats.

Science.gov (United States)

Hiner, Mark C; Rueden, Curtis T; Eliceiri, Kevin W

2016-12-07

No gold standard exists in the world of scientific image acquisition; a proliferation of instruments each with its own proprietary data format has made out-of-the-box sharing of that data nearly impossible. In the field of light microscopy, the Bio-Formats library was designed to translate such proprietary data formats to a common, open-source schema, enabling sharing and reproduction of scientific results. While Bio-Formats has proved successful for microscopy images, the greater scientific community was lacking a domain-independent framework for format translation. SCIFIO (SCientific Image Format Input and Output) is presented as a freely available, open-source library unifying the mechanisms of reading and writing image data. The core of SCIFIO is its modular definition of formats, the design of which clearly outlines the components of image I/O to encourage extensibility, facilitated by the dynamic discovery of the SciJava plugin framework. SCIFIO is structured to support coexistence of multiple domain-specific open exchange formats, such as Bio-Formats' OME-TIFF, within a unified environment. SCIFIO is a freely available software library developed to standardize the process of reading and writing scientific image formats.

Complex Formation Control of Large-Scale Intelligent Autonomous Vehicles

Directory of Open Access Journals (Sweden)

Ming Lei

2012-01-01

Full Text Available A new formation framework of large-scale intelligent autonomous vehicles is developed, which can realize complex formations while reducing data exchange. Using the proposed hierarchy formation method and the automatic dividing algorithm, vehicles are automatically divided into leaders and followers by exchanging information via wireless network at initial time. Then, leaders form formation geometric shape by global formation information and followers track their own virtual leaders to form line formation by local information. The formation control laws of leaders and followers are designed based on consensus algorithms. Moreover, collision-avoiding problems are considered and solved using artificial potential functions. Finally, a simulation example that consists of 25 vehicles shows the effectiveness of theory.

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

Star formations rates in the Galaxy

International Nuclear Information System (INIS)

Smith, L.F.; Mezger, P.G.; Biermann, P.

1978-01-01

Data relevant to giant HII regions in the Galaxy are collected. The production rate for Lyman continuum photons by O stars in giant HII regions is 4.7 10 52 s -1 in the whole Galaxy. The corresponding present rate of star formation is M (sun)/yr, of which 74% occurs in main spiral arms, 13% in the interarm region and 13% in the galactic center. The star formation rates, the observed heavy element and deuterium abundances in the solar neighbourhood are compared to model predictions based on star formation proportional to a power (k) of the gas surface density. The mass function is terminated at Msub(u)=100 M (sun) above and M 1 below. Msub(u)=50 M (sun) is also considered. Comparing with data derived from observations a) the star formation rate, b) metal abundances, c) deuterium abundances, and d) colors of the stellar population, we find that models of k=1/2 to 1, and M 1 1 M (sun) are formed together with O and B stars, but under rather special conditions of the interstellar gas, while lower mass stars form wherever dense molecular clouds exist. The high rate of star formation in the galactic center may represent a burst. (orig.) [de

INSTITUTIONAL ENVIRONMENT OF THE AGRICULTURAL MARKET FORMATION PROCESS

Directory of Open Access Journals (Sweden)

S. Revenko

2013-11-01

Full Text Available This article considers institutional aspects of the organized agricultural market formation process. Theoretical base to distinguish institute and institutes is given. In order to find out main influential institutes of the “organization” phenomenon author analyses Ukrainian institutional environment that is under construction process. Author considers main processes which are running during the organized market formation. Author researches theoretical approaches to the institutional staff. In order to structure the most common approaches and theoretical knowledge of this problem author proposes few schemes. Author’s points of view for many questions of the organized market formation process are proposed. Researcher analyzes effectiveness of the institutes and governmental regulation of the agricultural market. Readers can find strategically new approach to the agricultural market formation policy from the governmental point of view. Essence of the socioeconomic formation of agricultural market is considered. Main factors of agriculture market formation are outlined. Agricultural market structural parts consideration systematic approach is proposed. Ineffectiveness of the agriculture market relations without regulation process is proved. The most unfavorable reasons of the agricultural market formation are determined.

Recombinant human bone morphogenetic protein induces bone formation

International Nuclear Information System (INIS)

Wang, E.A.; Rosen, V.; D'Alessandro, J.S.; Bauduy, M.; Cordes, P.; Harada, T.; Israel, D.I.; Hewick, R.M.; Kerns, K.M.; LaPan, P.; Luxenberg, D.P.; McQuaid, D.; Moutsatsos, I.K.; Nove, J.; Wozney, J.M.

1990-01-01

The authors have purified and characterized active recombinant human bone morphogenetic protein (BMP) 2A. Implantation of the recombinant protein in rats showed that a single BMP can induce bone formation in vivo. A dose-response and time-course study using the rat ectopic bone formation assay revealed that implantation of 0.5-115 μg of partially purified recombinant human BMP-2A resulted in cartilage by day 7 and bone formation by day 14. The time at which bone formation occurred was dependent on the amount of BMP-2A implanted; at high doses bone formation could be observed at 5 days. The cartilage- and bone-inductive activity of the recombinant BMP-2A is histologically indistinguishable from that of bone extracts. Thus, recombinant BMP-2A has therapeutic potential to promote de novo bone formation in humans

Formation, Sintering and Removal of Biomass Ash Deposits

DEFF Research Database (Denmark)

Laxminarayan, Yashasvi

conditions in laboratory-scale setups. Deposit formation was simulated in an Entrained Flow Reactor, to investigate the effect of operating conditions and ash chemistry on the rate of deposit formation. Experiments were performed using model biomass fly ash, prepared from mixtures of K2Si4O9, KCl, K2SO4, Ca....... Moreover, biomass ash deposits may cause severe corrosion of boiler surfaces. Therefore, reducing deposit formation and timely deposit removal are essential for optimal boiler operation. The formation, sintering and removal of boiler deposits has been investigated in this PhD project, by simulating boiler...... temperature increased the sticking probability of the fly ash particles/deposit surface, thereby increasing the rate of deposit formation. However, increasing flue gas velocity resulted in a decrease in the deposit formation rate, due to increased particle rebound. Furthermore, it was observed...

Thermoluminescence dating of Rio Claro and Piracununga formations

International Nuclear Information System (INIS)

Ferreira, Sandra Regina; Chang, Maria Rita Caetano

2008-01-01

The Rio Claro and Piracununga formations cover extensive areas of the Paulista Peripheral Depression, dominantly in the region of Rio Claro and Piracununga cities. These units lie over the Corumbatai and Piramboia formations, exhibiting discordant contacts. The Rio Claro and Piracununga formations are composed of fine to medium sand facies, showing local cross-stratifications and parallel beddings with thin interbeddings of mud and gravel. These sands were dated by the Thermoluminescence Method, which indicated they were from the Pleistocene age. The oldest age (745,000 years BP) was found in deposits of the Rio Claro Formation; the other ages varied from 400,000 years BP to 145,000 years BP, for both formations. The youngest age (15,000 years BP - close to Pleistocene/ Holocene limit) was found in colluvial deposits, which rest on the Piracununga Formation. (author)

Temperature controlled formation of lead/acid batteries

Science.gov (United States)

Bungardt, M.

At present, standard formation programs have to accommodate the worst case. This is important, especially in respect of variations in climatic conditions. The standard must be set so that during the hottest weather periods the maximum electrolyte temperature is not exceeded. As this value is defined not only by the desired properties and the recipe of the active mass, but also by type and size of the separators and by the dimensions of the plates, general rules cannot be formulated. It is considered to be advantageous to introduce limiting data for the maximum temperature into a general formation program. The latter is defined so that under normal to good ambient conditions the shortest formation time is achieved. If required, the temperature control will reduce the currents employed in the different steps, according to need, and will extend the formation time accordingly. With computer-controlled formation, these parameters can be readily adjusted to suit each type of battery and can also be reset according to modifications in the preceding processing steps. Such a procedure ensures that: (i) the formation time is minimum under the given ambient conditions; (ii) in the event of malpractice ( e.g. actual program not fitting to size) the batteries will not be destroyed; (iii) the energy consumption is minimized (note, high electrolyte temperature leads to excess gassing). These features are incorporated in the BA/FOS-500 battery formation system developed by Digatron. The operational characteristics of this system are listed in Table 1.

Experimental study upon the effect of irradiation on callus formation of fracture. Observation of vascular alteration and callus formation

Energy Technology Data Exchange (ETDEWEB)

Saigusa, F [Nippon Dental Coll., Tokyo

1981-02-01

Irradiation effects on callus formation after bone fracture were studied in rats with fractured right lower extremity. Follow-up study was continued for 112 days since 3000 rad was irradiated to the fractured site 3 days after bone fracture. Callus formation was noted in both of the outer and inner part (bone marrow) of the diaphysis before 14 days after bone fracture, but it was slow and sparse compared with that of non-irradiated group. Callus formation tended to disappear gradually from the outside of the diaphysis after 28 days after bone fracture. Strong disturbance was found in the surrounding vascular system at this time. Inside of the diaphysis, callus formation was restricted the end of the fracture, where lamellar calluses fused together. Changes in vascular system remained until 56 days after bone fracture. Vascular distribution was most dense 28 days after bone fracture. In many of the calluses which have established fusion, findings suggested excessive calcification in the trabeculae. Vascular distribution at this time was sparse, vascular formation was markedly suppressed in the bone marrow, and very little vascular formation was found in the fractured edges of the bone.

Grammar-Based Specification and Parsing of Binary File Formats

Directory of Open Access Journals (Sweden)

William Underwood

2012-03-01

Full Text Available The capability to validate and view or play binary file formats, as well as to convert binary file formats to standard or current file formats, is critically important to the preservation of digital data and records. This paper describes the extension of context-free grammars from strings to binary files. Binary files are arrays of data types, such as long and short integers, floating-point numbers and pointers, as well as characters. The concept of an attribute grammar is extended to these context-free array grammars. This attribute grammar has been used to define a number of chunk-based and directory-based binary file formats. A parser generator has been used with some of these grammars to generate syntax checkers (recognizers for validating binary file formats. Among the potential benefits of an attribute grammar-based approach to specification and parsing of binary file formats is that attribute grammars not only support format validation, but support generation of error messages during validation of format, validation of semantic constraints, attribute value extraction (characterization, generation of viewers or players for file formats, and conversion to current or standard file formats. The significance of these results is that with these extensions to core computer science concepts, traditional parser/compiler technologies can potentially be used as a part of a general, cost effective curation strategy for binary file formats.

General certification procedure of formation organizations

CERN Document Server

Int. At. Energy Agency, Wien

2002-01-01

This document presents the procedure dealing with the certification of formation organizations dispensing the formation and the risks prevention to the personnel of A or B category in nuclear facilities. This certification proves the organization ability to satisfy the ''F'' specification of the CEFRI. (A.L.B.)

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...

Exoplanets Detection, Formation, Properties, Habitability

CERN Document Server

Mason, John W

2008-01-01

This edited, multi-author volume will be an invaluable introduction and reference to all key aspects in the field of exoplanet research. The reviews cover: Detection methods and properties of known exoplanets, Detection of extrasolar planets by gravitational microlensing. The formation and evolution of terrestrial planets in protoplanetary and debris disks. The brown dwarf-exoplanet connection. Formation, migration mechanisms and properties of hot Jupiters. Dynamics of multiple exoplanet systems. Doppler exoplanet surveys. Searching for exoplanets in the stellar graveyard. Formation and habitability of extra solar planets in multiple star systems. Exoplanet habitats and the possibilities for life. Moons of exoplanets: habitats for life. Contributing authors: •Rory Barnes •David P. Bennett •Jian Ge •Nader Haghighipour •Patrick Irwin •Hugh Jones •Victoria Meadows •Stanimir Metchev •I. Neill Reid •George Rieke •Caleb Scharf •Steinn Sigurdsson

Modularity in New Market Formation

DEFF Research Database (Denmark)

Sanchez, Ron; Hang, Chang Chieh

2017-01-01

In this paper we appraise the ways in which use of closed-system proprietary product architectures versus open-system modular product architectures is likely to influence the dynamics and trajectory of new product market formation. We compare the evolutions of new markets in China for gas......-powered two-wheeled vehicles (G2WVs) based (initially) on closed-system proprietary architectures and for electric-powered two-wheeled vehicles (E2WVs) based on open-system modular architectures. We draw on this comparison to suggest ways in which the use of the two different kinds of architectures...... as the basis for new kinds of products may result in very different patterns and speeds of new market formation. We then suggest some key implications of the different dynamics of market formation associated with open-system modular architectures for both the competence-based strategic management (CBSM...

Star Cluster Structure from Hierarchical Star Formation

Science.gov (United States)

Grudic, Michael; Hopkins, Philip; Murray, Norman; Lamberts, Astrid; Guszejnov, David; Schmitz, Denise; Boylan-Kolchin, Michael

2018-01-01

Young massive star clusters (YMCs) spanning 104-108 M⊙ in mass generally have similar radial surface density profiles, with an outer power-law index typically between -2 and -3. This similarity suggests that they are shaped by scale-free physics at formation. Recent multi-physics MHD simulations of YMC formation have also produced populations of YMCs with this type of surface density profile, allowing us to narrow down the physics necessary to form a YMC with properties as observed. We show that the shallow density profiles of YMCs are a natural result of phase-space mixing that occurs as they assemble from the clumpy, hierarchically-clustered configuration imprinted by the star formation process. We develop physical intuition for this process via analytic arguments and collisionless N-body experiments, elucidating the connection between star formation physics and star cluster structure. This has implications for the early-time structure and evolution of proto-globular clusters, and prospects for simulating their formation in the FIRE cosmological zoom-in simulations.

Septum formation of the lateral ventricles

International Nuclear Information System (INIS)

Celik, Hakan H.; Aldur, Mustafa M.; Tatar, I.; Tascioglu, A.B.

2005-01-01

In an MRI study examining anomalies of the septum pellucidum in 505 cases, we detected bilateral septum formation of the lateral ventricles in a 17-months-old-baby. In this study, we evaluate 505 (242 males and 263 females) patients referred to the Emaray Imaging Center, Ankara, Turkey with various prediagnoses. We specially selected all the cases from a non-psychotic population. We obtained MRI scans on a 1-Tesla imager (Picker International, Highland Heights, Ohio, USA), with slices of 5 and 6 mm thickness. In the axial and coronal sections, we observed septum formation laterally between the anterior horn and the ventricular body of the lateral ventricles. Radio opaque septum formations started from the caudate nucleus and stretched to the genu of the corpus callosum. There was a second septum formation between the posterior horn and the ventricular body of the right lateral ventricle. It started from the caudate nucleus and stretched to the cavum vergae. (author)

Theoretical Aspects of Enterprise Business Strategy Formation

OpenAIRE

Valentinavičius, Stasys

2009-01-01

The paper presents interpretations of business strategy concept and analyses strategy planning and formation, models. The concept of business strategy is revised and formulated considering various authors approaches. Analysis of business strategy formation process – steps of development and management, selection of strategy type – is based on presented strategy planning models. The aspects of enterprise business and investment strategy formation, coordination and valuation are analysed. The s...

Formation rate of natural gas hydrate

Energy Technology Data Exchange (ETDEWEB)

Mork, Marit

2002-07-01

The rate of methane hydrate and natural gas hydrate formation was measured in a 9.5 litre stirred tank reactor of standard design. The experiments were performed to better understand the performance and scale-up of a reactor for continuous production of natural gas hydrates. The hydrate formation rate was measured at steady-state conditions at pressures between 70 and 90 bar and temperatures between 7 and 15 deg C. Between 44 and 56 % of the gas continuously supplied to the reactor was converted to hydrate. The experimental results show that the rate of hydrate formation is strongly influenced by gas injection rate and pressure. The effect of stirring rate is less significant and subcooling has no observable effect on the formation rate. Hydrate crystal concentration and gas composition do not influence the hydrate formation rate. Observations of produced hydrate crystals indicate that the crystals are elongated, about 5 micron in diameter and 10 micron long. Analysis of the results shows that the rate of hydrate formation is dominated by gas-liquid mass transfer. A mass transfer model, the bubble-to-crystal model, was developed for the hydrate formation rate in a continuous stirred tank reactor, given in terms of concentration driving force and an overall mass transfer coefficient. The driving force is the difference between the gas concentration at the gas-liquid interface and at the hydrate crystal surface. These concentrations correspond to the solubility of gas in water at experimental temperature and pressure and the solubility of gas at hydrate equilibrium temperature and experimental pressure, respectively. The overall mass transfer coefficient is expressed in terms of superficial gas velocity and impeller power consumption, parameters commonly used in study of stirred tank reactors. Experiments and modeling show that the stirred tank reactor has a considerable potential for increased production capacity. However, at higher hydrate production rates the

The multifaceted planetesimal formation process

DEFF Research Database (Denmark)

Johansen, Anders; Blum, Jürgen; Tanaka, Hidekazu

2013-01-01

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...... for planetesimal formation where particle growth starts unaided by self-gravity but later proceeds inside gravitationally collapsing pebble clumps to form planetesimals with a wide range of sizes....

Ministerial formation of theological students through distance education

Directory of Open Access Journals (Sweden)

Marilyn Naidoo

2012-02-01

Full Text Available Ministerial formation is a multifaceted activity involving critical thinking, the acquisition of knowledge, skills development, religious identity formation and the development of ministerial and spiritual maturity expected of church ministers. Education is not merely the accumulation of a prescribed set of academic credits but includes the holistic formation of all aspects of the individual. However, theological educators are concerned about the capacity to foster such values and skills in the distance and electronic environment. Some see distance education as ‘distancing’ the students in more significant ways than simply geographic distance. These issues are of fundamental importance for they reflect the deeper convictions of theologians that distance education may not be a suitable medium for ministerial formation. This article creates a conceptual map of the theological and pedagogical challenges for ministerial formation and highlights how the possibility of formation is being carried out in the distance-learning environment.

Provenance of Austroalpine basement metasediments: tightening up Early Palaeozoic connections between peri-Gondwanan domains of central Europe and Northern Africa

Science.gov (United States)

Siegesmund, S.; Oriolo, S.; Heinrichs, T.; Basei, M. A. S.; Nolte, N.; Hüttenrauch, F.; Schulz, B.

2018-03-01

New U-Pb and Lu-Hf detrital zircon data together with whole-rock geochemical and Sm-Nd data were obtained for paragneisses of the Austroalpine basement south of the Tauern Window. Geochemically immature metasediments of the Northern-Defereggen-Petzeck (Ötztal-Bundschuh nappe system) and Defereggen (Drauzug-Gurktal nappe system) groups contain zircon age populations which indicate derivation mainly from Pan-African orogens. Younger, generally mature metasediments of the Gailtal Metamorphic Basement (Drauzug-Gurktal nappe system), Thurntaler Phyllite Group (Drauzug-Gurktal nappe system) and Val Visdende Formation (South Alpine Basement) were possibly derived from more distant sources. Their significantly larger abundances of pre-Pan-African zircons record a more advanced stage of downwearing of the Pan-African belts and erosion of older basement when the Austroalpine terrane was part of the Early Palaeozoic Northern Gondwana passive margin. Most zircon age spectra are dominated by Ediacaran sources, with lesser Cryogenian, Tonian and Stenian contributions and subordinate Paleoproterozoic and Neoarchean ages. These age patterns are similar to those recorded by Cambro-Ordovician sedimentary sequences in northeastern Africa between Libya and Jordan, and in some pre-Variscan basement inliers of Europe (e.g. Dinarides-Hellenides, Alboran microplate). Therefore, the most likely sources seem to be in the northeastern Saharan Metacraton and the Northern Arabian-Nubian Shield (Sinai), further supported by whole-rock Sm-Nd and zircon Lu-Hf data.

Formation and evolution of compact binaries

NARCIS (Netherlands)

Sluijs, Marcel Vincent van der

2006-01-01

In this thesis we investigate the formation and evolution of compact binaries. Chapters 2 through 4 deal with the formation of luminous, ultra-compact X-ray binaries in globular clusters. We show that the proposed scenario of magnetic capture produces too few ultra-compact X-ray binaries to explain

Combustion chemistry and formation of pollutants; Chimie de la combustion et formation des polluants

Energy Technology Data Exchange (ETDEWEB)

NONE

1996-12-31

This book of proceedings reports on 7 papers on combustion chemistry and formation of pollutants presented during the workshop organized by the `Combustion and Flames` section of the French society of thermal engineers. The chemistry of combustion is analyzed in various situations such as: turbojet engines, spark ignition engines, industrial burners, gas turbines etc... Numerical simulation is used to understand the physico-chemical processes involved in combustion, to describe the kinetics of oxidation, combustion and flame propagation, and to predict the formation of pollutants. (J.S.)

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.

Superclusters and galaxy formation

International Nuclear Information System (INIS)

Einasto, J.; Joeveer, M.; Saar, E.

1979-01-01

The spatial distribution of Galaxies and Galaxy congestions in the southern galactic hemisphere is studied. The rich galaxy congestions, containing many elliptic Galaxies and radiogalaxies, are linked with each other by chains of scanty congestions with moderate content of elliptic Galaxies and radiogalaxies. The flat formation, linking the density pikes and the intermediate chains, can reasonably be called supercongestion. In the central region of supercongestions there is a thin layer of Galaxies consisting of only spiral Galaxies. The neighbouring supercongestions touch each other, while the intersupercongestion space contains no Galaxy congestions and almost no Galaxies. It is shown that such a structure was, apparently, formed before the formation of Galaxies

Implication of formative assessment practices among mathematics teacher

Science.gov (United States)

Samah, Mas Norbany binti Abu; Tajudin, Nor'ain binti Mohd

2017-05-01

Formative assessment of school-based assessment (SBA) is implemented in schools as a move to improve the National Education Assessment System (NEAS). Formative assessment focuses on assessment for learning. There are various types of formative assessment instruments used by teachers of mathematics, namely the form of observation, questioning protocols, worksheets and quizzes. This study aims to help teachers improve skills in formative assessments during the teaching and learning (t&l) Mathematics. One mathematics teacher had been chosen as the study participants. The collecting data using document analysis, observation and interviews. Data were analyzed narrative and assessments can help teachers implement PBS. Formative assessment is conducted to improve the skills of students in t&l effectively.

MILLIMETER WAVE SPECTRUM AND ASTRONOMICAL SEARCH FOR VINYL FORMATE

Energy Technology Data Exchange (ETDEWEB)

Alonso, E. R.; Kolesniková, L.; Cabezas, C.; Alonso, J. L. [Grupo de Espectroscopia Molecular (GEM), Edificio Quifima, Área de Química-Física, Laboratorios de Espectroscopia y Bioespectroscopia, Parque Científico UVa, Unidad Asociada CSIC, Universidad de Valladolid, E-47011 Valladolid (Spain); Tercero, B.; Cernicharo, J. [Grupo de Astrofísica Molecular, ICMM-CSIC, C/Sor Juana Inés de la Cruz 3, E-28049 Cantoblanco (Spain); Guillemin, J.-C. [Institut des Sciences Chimiques de Rennes, École Nationale Supérieure de Chimie de Rennes, CNRS, UMR 6226, 11 Allée de Beaulieu, CS 50837, F-35708 Rennes Cedex 7 (France)

2016-11-20

Previous detections of methyl and ethyl formate make other small substituted formates potential candidates for observation in the interstellar medium. Among them, vinyl formate is one of the simplest unsaturated carboxylic ester. The aim of this work is to provide direct experimental frequencies of the ground vibrational state of vinyl formate in a large spectral range for astrophysical use. The room-temperature rotational spectrum of vinyl formate has been measured from 80 to 360 GHz and analyzed in terms of Watson’s semirigid rotor Hamiltonian. Two thousand six hundred transitions within J = 3–88 and K {sub a} = 0–28 were assigned to the most stable conformer of vinyl formate and a new set of spectroscopic constants was accurately determined. Spectral features of vinyl formate were then searched for in Orion KL, Sgr B2(N), B1-b, and TMC-1 molecular clouds. Upper limits to the column density of vinyl formate are provided.

On the formation of sulphuric acid – amine clusters in varying atmospheric conditions and its influence on atmospheric new particle formation

Directory of Open Access Journals (Sweden)

I. K. Ortega

2012-10-01

Full Text Available Sulphuric acid is a key component in atmospheric new particle formation. However, sulphuric acid alone does not form stable enough clusters to initiate particle formation in atmospheric conditions. Strong bases, such as amines, have been suggested to stabilize sulphuric acid clusters and thus participate in particle formation. We modelled the formation rate of clusters with two sulphuric acid and two amine molecules (JA2B2 at varying atmospherically relevant conditions with respect to concentrations of sulphuric acid ([H2SO4], dimethylamine ([DMA] and trimethylamine ([TMA], temperature and relative humidity (RH. We also tested how the model results change if we assume that the clusters with two sulphuric acid and two amine molecules would act as seeds for heterogeneous nucleation of organic vapours (other than amines with higher atmospheric concentrations than sulphuric acid. The modelled formation rates JA2B2 were functions of sulphuric acid concentration with close to quadratic dependence, which is in good agreement with atmospheric observations of the connection between the particle formation rate and sulphuric acid concentration. The coefficients KA2B2 connecting the cluster formation rate and sulphuric acid concentrations as JA2B2=KA2B2[H2SO4]2 turned out to depend also on amine concentrations, temperature and relative humidity. We compared the modelled coefficients KA2B2 with the corresponding coefficients calculated from the atmospheric observations (Kobs from environments with varying temperatures and levels of anthropogenic influence. By taking into account the modelled behaviour of JA2B2 as a function of [H2SO4], temperature and RH, the atmospheric particle formation rate was reproduced more closely than with the traditional semi-empirical formulae based on sulphuric acid concentration only. The formation rates of clusters with two sulphuric acid and two amine molecules with different amine compositions (DMA or TMA or one of both had

Fostering Spiritual Formation of Millennials in Christian Schools

Science.gov (United States)

Horan, Anne Puidk

2017-01-01

Christian education seeks to foster millennials' spiritual formation to equip them for future challenges and to benefit society. Using nonexperimental mixed methods, 504 secondary educators revealed what spiritual formation programs their schools implement and their perceptions about millennial spiritual formation. Descriptive analysis showed that…

Inhibition of the anaerobic acetate degradation by formate

OpenAIRE

Guyot, Jean-Pierre; Ramirez, F.

1989-01-01

Granular sludge from an UASB reactor fed with VFA showed a very low affinity for formate which provide little support to the theory of interspecies formate transfer. It is shown that formate can inhibit acetate degradation by anaerobic sludge. (Résumé d'auteur)

The formation mechanism of lactones in Gouda cheese

NARCIS (Netherlands)

Alewijn, M.; Smit, B.; Sliwinski, E.L.; Wouters, J.T.M.

2007-01-01

Lactones are fat-derived aroma compounds, but the formation mechanism of these compounds during ripening of Gouda cheese is unknown. Both enzymatic and chemical formation pathways were investigated in this study. Lactone formation from milk triglycerides or free fatty acids by lactic acid bacteria

Aggregate formation in 3D turbulent-like flows

NARCIS (Netherlands)

Dominguez, A.; Clercx, H.J.H.

2006-01-01

Aggregate formation is an important process in industrial and environmental turbulent flows. In oceans turbulence play an important role on Marine Snow (aggregate) formation. For a proper description, the study of aggregate formation in turbulent flows requires a particle based model i.e. following

Time-Dependent Dust Formation in Novae

Directory of Open Access Journals (Sweden)

Kyung-Won Suh

1991-06-01

Full Text Available The dust formation processes in novae are investigated with close attention to recent infrared observations. Using mainly the classical nucleation theory, we have calculated the time scales of dust formation and growth in the environments of novae. Those time scales roughly resemble the typical observations. We have classified the dust-forming novae into three classes according to their explosion properties and the thermodynamic properties of dust grains. Oxygen grains from much later than carbon grains because of their thermodynamic properties. The effect of grain formation to the efficiency of stellar winds to drive the material outward is tested with newly obtained Planck mean values of dust grains.

Formation enthalpy of alkali-borosilicate glass

International Nuclear Information System (INIS)

Borisova, N.V.; Ushakov, V.M.

1991-01-01

Temperature dependence of formation enthalpy of glass of the composition 0.0438Na 2 O-0.0385K 2 O-0.3394B 2 O 3 -0.5783SiO 2 was determined using the method of high-temperature colorimetry-dissolution, mixing and differential scanning calorimetry. The glass considered has liquation nature-two-vitrification ranges at 713 K and 817 K are detected. The brightening point is 922 K. The calculation of formation enthalpy using the method of partial heat capacities is made in the temperature range of 973-1473 K. Formation enthalpy does not depend on temperature in the temperature range of 298-1273 K

New method for determination of star formation history

OpenAIRE

Čeponis, Marius

2017-01-01

A New Method for Determination of Star Formation History Without stars there would not be any life and us. Almost all elements in our bodies are made in stars. Yet we still don‘t fully understand all the processes governing formation and evolution of stellar systems. Their star formation histories really help in trying to understand these processes. In this work a new Bayesian method for determination of star formation history is proposed. This method uses photometric data of resolved stars a...

Efficient stereoscopic contents file format on the basis of ISO base media file format

Science.gov (United States)

Kim, Kyuheon; Lee, Jangwon; Suh, Doug Young; Park, Gwang Hoon

2009-02-01

A lot of 3D contents haven been widely used for multimedia services, however, real 3D video contents have been adopted for a limited applications such as a specially designed 3D cinema. This is because of the difficulty of capturing real 3D video contents and the limitation of display devices available in a market. However, diverse types of display devices for stereoscopic video contents for real 3D video contents have been recently released in a market. Especially, a mobile phone with a stereoscopic camera has been released in a market, which provides a user as a consumer to have more realistic experiences without glasses, and also, as a content creator to take stereoscopic images or record the stereoscopic video contents. However, a user can only store and display these acquired stereoscopic contents with his/her own devices due to the non-existence of a common file format for these contents. This limitation causes a user not share his/her contents with any other users, which makes it difficult the relevant market to stereoscopic contents is getting expanded. Therefore, this paper proposes the common file format on the basis of ISO base media file format for stereoscopic contents, which enables users to store and exchange pure stereoscopic contents. This technology is also currently under development for an international standard of MPEG as being called as a stereoscopic video application format.

Cosmic strings and galaxy formation

Science.gov (United States)

Bertschinger, Edmund

1989-01-01

The cosmogonical model proposed by Zel'dovich and Vilenkin (1981), in which superconducting cosmic strings act as seeds for the origin of structure in the universe, is discussed, summarizing the results of recent theoretical investigations. Consideration is given to the formation of cosmic strings, the microscopic structure of strings, gravitational effects, cosmic string evolution, and the formation of galaxies and large-scale structure. Simulation results are presented in graphs, and several outstanding issues are listed and briefly characterized.

Star formation in evolving molecular clouds

Science.gov (United States)

Völschow, M.; Banerjee, R.; Körtgen, B.

2017-09-01

Molecular clouds are the principle stellar nurseries of our universe; they thus remain a focus of both observational and theoretical studies. From observations, some of the key properties of molecular clouds are well known but many questions regarding their evolution and star formation activity remain open. While numerical simulations feature a large number and complexity of involved physical processes, this plethora of effects may hide the fundamentals that determine the evolution of molecular clouds and enable the formation of stars. Purely analytical models, on the other hand, tend to suffer from rough approximations or a lack of completeness, limiting their predictive power. In this paper, we present a model that incorporates central concepts of astrophysics as well as reliable results from recent simulations of molecular clouds and their evolutionary paths. Based on that, we construct a self-consistent semi-analytical framework that describes the formation, evolution, and star formation activity of molecular clouds, including a number of feedback effects to account for the complex processes inside those objects. The final equation system is solved numerically but at much lower computational expense than, for example, hydrodynamical descriptions of comparable systems. The model presented in this paper agrees well with a broad range of observational results, showing that molecular cloud evolution can be understood as an interplay between accretion, global collapse, star formation, and stellar feedback.

Delayed star formation in isolated dwarf galaxies: Hubble space telescope star formation history of the Aquarius dwarf irregular

Energy Technology Data Exchange (ETDEWEB)

Cole, Andrew A. [School of Physical Sciences, University of Tasmania, Private Bag 37, Hobart, Tasmania, 7001 Australia (Australia); Weisz, Daniel R. [Department of Astronomy, University of California at Santa Cruz, 1156 High Street, Santa Cruz, CA 95064 (United States); Dolphin, Andrew E. [Raytheon, 1151 East Hermans Road, Tucson, AZ 85706 (United States); Skillman, Evan D. [Minnesota Institute for Astrophysics, University of Minnesota, Minneapolis, MN 55441 (United States); McConnachie, Alan W. [NRC Herzberg Institute of Astrophysics, Dominion Astrophysical Observatory, Victoria, BC, V9E 2E7 Canada (Canada); Brooks, Alyson M. [Department of Physics and Astronomy, Rutgers, The State University of New Jersey, 136 Frelinghuysen Road, Piscataway, NJ 08854 (United States); Leaman, Ryan, E-mail: andrew.cole@utas.edu.au, E-mail: drw@ucsc.edu, E-mail: adolphin@raytheon.com, E-mail: skillman@astro.umn.edu, E-mail: alan.mcconnachie@nrc-cnrc.gc.ca, E-mail: abrooks@physics.rutgers.edu, E-mail: rleaman@iac.es [Instituto de Astrofísica de Canarias, E-38205 La Laguna, Tenerife (Spain)

2014-11-01

We have obtained deep images of the highly isolated (d = 1 Mpc) Aquarius dwarf irregular galaxy (DDO 210) with the Hubble Space Telescope Advanced Camera for Surveys. The resulting color-magnitude diagram (CMD) reaches more than a magnitude below the oldest main-sequence turnoff, allowing us to derive the star formation history (SFH) over the entire lifetime of the galaxy with a timing precision of ≈10% of the lookback time. Using a maximum likelihood fit to the CMD we find that only ≈10% of all star formation in Aquarius took place more than 10 Gyr ago (lookback time equivalent to redshift z ≈ 2). The star formation rate increased dramatically ≈6-8 Gyr ago (z ≈ 0.7-1.1) and then declined until the present time. The only known galaxy with a more extreme confirmed delay in star formation is Leo A, a galaxy of similar M {sub H} {sub I}/M {sub *}, dynamical mass, mean metallicity, and degree of isolation. The delayed stellar mass growth in these galaxies does not track the mean dark matter accretion rate from CDM simulations. The similarities between Leo A and Aquarius suggest that if gas is not removed from dwarf galaxies by interactions or feedback, it can linger for several gigayears without cooling in sufficient quantity to form stars efficiently. We discuss possible causes for the delay in star formation including suppression by reionization and late-time mergers. We find reasonable agreement between our measured SFHs and select cosmological simulations of isolated dwarfs. Because star formation and merger processes are both stochastic in nature, delayed star formation in various degrees is predicted to be a characteristic (but not a universal) feature of isolated small galaxies.

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

The Role of Trust in Costly Network Formation

NARCIS (Netherlands)

Gilles, R.P.; Sarangi, S.

2003-01-01

We consider game theoretic models of social network formation.In this paper we limit our investigation to game theoretic models of network formation that are based on individual actions only.Our approach is based on three simple and realistic principles: (1) Link formation is a binary process of

Star formation in the outskirts of disk galaxies

NARCIS (Netherlands)

Ferguson, AMN

2002-01-01

The far outer regions of galactic disks allow an important probe of both star formation and galaxy formation. I discuss how observations of HII regions in these low gas density, low metallicity environments can shed light on the physical processes which drive galactic star formation. The history of

Formation of stars and stellar clusters in galactic environment

OpenAIRE

Smilgys, Romas

2018-01-01

Star and stellar cluster formation in spiral galaxies is one of the biggest questions of astrophysics. In this thesis, I study how star formation, and the formation of stellar clusters, proceeds using SPH simulations. These simulations model a region of 400 pc and 10⁷ solar masses. Star formation is modelled through the use of sink particles which represent small groups of stars. Star formation occurs in high density regions, created by galactic spiral arm passage. The spiral shock compresses...

A Faculty Toolkit for Formative Assessment in Pharmacy Education.

Science.gov (United States)

DiVall, Margarita V; Alston, Greg L; Bird, Eleanora; Buring, Shauna M; Kelley, Katherine A; Murphy, Nanci L; Schlesselman, Lauren S; Stowe, Cindy D; Szilagyi, Julianna E

2014-11-15

This paper aims to increase understanding and appreciation of formative assessment and its role in improving student outcomes and the instructional process, while educating faculty on formative techniques readily adaptable to various educational settings. Included are a definition of formative assessment and the distinction between formative and summative assessment. Various formative assessment strategies to evaluate student learning in classroom, laboratory, experiential, and interprofessional education settings are discussed. The role of reflective writing and portfolios, as well as the role of technology in formative assessment, are described. The paper also offers advice for formative assessment of faculty teaching. In conclusion, the authors emphasize the importance of creating a culture of assessment that embraces the concept of 360-degree assessment in both the development of a student's ability to demonstrate achievement of educational outcomes and a faculty member's ability to become an effective educator.

Formatting Open Science: agilely creating multiple document formats for academic manuscripts with Pandoc Scholar

Directory of Open Access Journals (Sweden)

Albert Krewinkel

2017-05-01

Full Text Available The timely publication of scientific results is essential for dynamic advances in science. The ubiquitous availability of computers which are connected to a global network made the rapid and low-cost distribution of information through electronic channels possible. New concepts, such as Open Access publishing and preprint servers are currently changing the traditional print media business towards a community-driven peer production. However, the cost of scientific literature generation, which is either charged to readers, authors or sponsors, is still high. The main active participants in the authoring and evaluation of scientific manuscripts are volunteers, and the cost for online publishing infrastructure is close to negligible. A major time and cost factor is the formatting of manuscripts in the production stage. In this article we demonstrate the feasibility of writing scientific manuscripts in plain markdown (MD text files, which can be easily converted into common publication formats, such as PDF, HTML or EPUB, using Pandoc. The simple syntax of Markdown assures the long-term readability of raw files and the development of software and workflows. We show the implementation of typical elements of scientific manuscripts—formulas, tables, code blocks and citations—and present tools for editing, collaborative writing and version control. We give an example on how to prepare a manuscript with distinct output formats, a DOCX file for submission to a journal, and a LATEX/PDF version for deposition as a PeerJ preprint. Further, we implemented new features for supporting ‘semantic web’ applications, such as the ‘journal article tag suite’—JATS, and the ‘citation typing ontology’—CiTO standard. Reducing the work spent on manuscript formatting translates directly to time and cost savings for writers, publishers, readers and sponsors. Therefore, the adoption of the MD format contributes to the agile production of open science

Self-regulating star formation and disk structure

International Nuclear Information System (INIS)

Dopita, M.A.

1987-01-01

Star formation processes determine the disk structure of galaxies. Stars heavier than about 1 solar mass determine the chemical evolution of the system and are produced at a rate which maintains (by the momentum input of the stars) the phase structure, pressure, and vertical velocity dispersion of the gas. Low mass stars are produced quiescently within molecular clouds, and their associated T-Tauri winds maintain the support of molecular clouds and regulate the star formation rate. Inefficient cooling suppresses this mode of star formation at low metallicity. Applied to the solar neighborhood, such a model can account for age/metallicity relationships, the increase in the O/Fe ratio at low metallicity, the paucity of metal-poor G and K dwarf stars, the missing mass in the disk and, possibly, the existence of a metal-poor thick disk. For other galaxies, it accounts for constant w-velocity dispersion of the gas, the relationship between gas content and specific rates of star formation, the surface brightness/metallicity relationship and for the shallow radial gradients in both star formation rates and HI content. 71 references

Requirements for a next generation nuclear data format

International Nuclear Information System (INIS)

Archier, Pascal; Jouanne, Cedric; Peneliau, Yannick; Saint-Jean, Cyrille de; Trama, Jean-Christophe; Becky, Bret; Cullen, D.E. Red; Mattoony, Caleb; McNabb, Dennis; Brownyz, David; Herman, Michal; Johnson, Timothy; Sonzogni, Alejandro; Cabellos, Oscar; Capote Noy, Roberto; Forrest, Robin; Trkov, Andrej; Zerkiny, Viktor; Go, Chiba; Conliny, Jeremy Lloyd; Kahler, A.H. Skip; Talouy, Patrick; Whitey, Morgan C.; Cornock, Mark; Coste-Delclaux, Mireille; Malvagi, Fausto; Dunn, Michael; Leal, Luiz; Pigni, Marco; Wiarda, Dorothea; Dupont, Emmeric; Fischer, Ulrich; Tokio, Fukahori; Makoto, Ishikawa; Osamu, Iwamoto; Chikara, Konno; Teruhiko, Kugo; Kenji, Nishihara; Tatsuhiko, Sato; Kenya, Suyama; Kenji, Yokoyama; Haeck, Wim; Hawari, Ayman; Holmes, Jessie; Jacqmin, Robert; Noguere, Gilles; Kodeli, Ivo; Koningy, Arjan; Lee, Morgan; Sublet, Jean-Christophe; Lubitz, Cecil; Romano, Paul; Millsy, Robert; Roubtsovy, Danila; Scopatz, Anthony; Sinitsa, Valentin; Soppera, Nicolas; Vogty, Romona

2015-01-01

This document attempts to compile the requirements for the top-levels of a hierarchical arrangement of nuclear data such as is found in the ENDF format. This set of requirements will be used to guide the development of a new set of formats to replace the legacy ENDF format. (authors)

Modeling of tethered satellite formations using graph theory

DEFF Research Database (Denmark)

Larsen, Martin Birkelund; Smith, Roy S; Blanke, Mogens

2011-01-01

satellite formation and proposes a method to deduce the equations of motion for the attitude dynamics of the formation in a compact form. The use of graph theory and Lagrange mechanics together allows a broad class of formations to be described using the same framework. A method is stated for finding...

Probes of Cosmic Star Formation History

Indian Academy of Sciences (India)

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 ...

Seroma formation after surgery for breast cancer

Directory of Open Access Journals (Sweden)

Ebrahimi Mandana

2004-12-01

Full Text Available Abstract Background Seroma formation is the most frequent postoperative complication after breast cancer surgery. We carried out a study to investigate the effect of various demographic, clinical and therapeutic variables on seroma formation. Patients and methods A retrospective cross sectional study of patients who underwent surgical therapy for breast cancer with either modified radical mastectomy (MRM or breast preservation (BP was carried out. The demographic data and clinical information were extracted from case records. Seroma formation was studied in relation to age, type of surgery, tumor size, nodal involvement, preoperative chemotherapy, surgical instrument (electrocautery or scalpel, use of pressure garment, and duration of drainage. The multiple logistic regression analysis was performed to estimate odds ratios. Results A total of 158 patients with breast cancer were studied. The mean age of the patients was 46.3 years (SD ± 11.9. Seventy-three percent underwent modified radical mastectomy and the remaining 27% received breast preservation surgery. Seroma occurred in 35% of patients. In multivariate logistic regression analysis an association of postoperative seroma formation was noted with modified radical mastectomy (OR = 2.83, 95% CI 1.01–7.90, P = 0.04. No other factor studied was found to significantly effect the seroma formation after breast cancer surgery. Conclusion The findings suggest that the type of surgery is a predicting factor for seroma formation in breast cancer patients.

Method of treating non-supporting underground formations

International Nuclear Information System (INIS)

Anderson, B.W.; Trotty, K.D.

1977-01-01

Method of treating non-supporting underground formations, through which passes a borehole, aimed at preventing the transport of sand particles from the formation into the borehole during conveyance of liquids. (orig./RW) [de

Habit formation, work ethics, and technological progress

OpenAIRE

Faria, João Ricardo; León-Ledesma, Miguel A.

2002-01-01

Work ethics affects labor supply. This idea is modeled assuming that work is habit forming. This paper introduces working habits in a neoclassical growth model and compares its outcomes with a model without habit formation. In addition, it analyzes the impact of different forms of technical progress. The findings are that i) labor supply in the habit formation case is higher than in the neoclassical case; ii) unlike in the neoclassical case, labor supply in the presence of habit formation wil...

Negative ion formation and neutralization processes, (1)

International Nuclear Information System (INIS)

Sugiura, Toshio

1982-01-01

This review has been made preliminary for the purpose of contribute to the plasma heating by ''negative ion based neutral beam injection'' in the magnetic confinement fusion reactor. A compilation includes the survey of the general processes of negative ion formation, the data of the cross section of H - ion formation and the neutralization of H - ion, and some of new processes of H - ion formation. The data of cross section are mainly experimental, but partly include the results of theoretical calculation. (author)

Specific plant induced biofilm formation in Methylobacterium species

Science.gov (United States)

Rossetto, Priscilla B.; Dourado, Manuella N.; Quecine, Maria C.; Andreote, Fernando D.; Araújo, Welington L.; Azevedo, João L.; Pizzirani-Kleiner, Aline A.

2011-01-01

Two endophytic strains of Methylobacterium spp. were used to evaluate biofilm formation on sugarcane roots and on inert wooden sticks. Results show that biofilm formation is variable and that plant surface and possibly root exudates have a role in Methylobacterium spp. host recognition, biofilm formation and successful colonization as endophytes. PMID:24031703

Cosmic strings and galaxy formation

International Nuclear Information System (INIS)

Bertschinger, E.

1989-01-01

Cosmic strings have become increasingly popular candidates as seeds for the formation of structure in the universe. This scenario, remains a serious cosmogonical model despite close scrutiny. In constrast, magnetic monopoles and domain walls - relic topological defects as are cosmic strings - are disastrous for cosmology if they are left over from the early universe. The production of heavy cosmic strings is speculative, as it depends on the details of ultrahigh energy physics. Fortunately, speculation about cosmic strings is not entirely idle because, if they exist and are heavy enough to seed galaxy formation, cosmic strings can be detected astronomically. Failure to detect cosmic strings would impose some constraints on grand unified theories (GUTs); their discovery would have exciting consequences for high energy physics and cosmology. This article reviews the basic physics of nonsuperconducting cosmic strings, highlighting the field theory aspects, and provides a progress report on calculations of structure formation with cosmic strings

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.

25 CFR 82.6 - Petition format.

Science.gov (United States)

2010-04-01

... 25 Indians 1 2010-04-01 2010-04-01 false Petition format. 82.6 Section 82.6 Indians BUREAU OF... REORGANIZED UNDER FEDERAL STATUTE AND OTHER ORGANIZED TRIBES § 82.6 Petition format. Petitions may consist of... of a petition must set forth at least a summary of the objectives of the petitioners and must show...

Triggered star formation

Czech Academy of Sciences Publication Activity Database

Palouš, Jan; Ehlerová, Soňa

2002-01-01

Roč. 12, - (2002), s. 35-36 ISSN 1405-2059 R&D Projects: GA AV ČR IAA3003705; GA AV ČR KSK1048102 Institutional research plan: CEZ:AV0Z1003909 Keywords : interstellar medium * star formation * HI shells Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics

Microbial processes in banded iron formation deposition

DEFF Research Database (Denmark)

Posth, Nicole; Konhauser, Kurt; Kappler, Andreas

2013-01-01

, remains unresolved. Evidence of an anoxic Earth with only localized oxic areas until the Great Oxidation Event ca 2·45 to 2·32 Ga makes the investigation of O2-independent mechanisms for banded iron formation deposition relevant. Recent studies have explored the long-standing proposition that Archean......Banded iron formations have been studied for decades, particularly regarding their potential as archives of the Precambrian environment. In spite of this effort, the mechanism of their deposition and, specifically, the role that microbes played in the precipitation of banded iron formation minerals...... banded iron formations may have been formed, and diagenetically modified, by anaerobic microbial metabolisms. These efforts encompass a wide array of approaches including isotope, ecophysiological and phylogeny studies, molecular and mineral marker analysis, and sedimentological reconstructions. Herein...

Gravitational instability, evolution of galaxies and star formation

International Nuclear Information System (INIS)

Palous, J.

1979-01-01

The gravitational collapse is the key to the theories of galaxy and star formation. The observations, showing intrinsic differences between elliptical and spiral galaxies, guide our fundamental conceptions on the formation and evolution of systems in question. Stars in elliptical galaxies and in spherical components of spiral galaxies were formed in a short period of time during early phases of protogalactic collapse, at a time of violent star formation. The disc-like components of spiral galaxies, however, were built gradually in the course of galactic evolution. Star formation in elliptical galaxies is described by the collision model of interstellar clouds, while star formation in discs is characterised by several processes: the expansion of HII regions, the expansion of supernovae remnants and the shock wave related to the presence of the spiral structure. (author)

Seminary Formation: A Case Study from the Pontifical Beda College, Rome

Science.gov (United States)

Strange, Roderick

2015-01-01

This case study account reviews issues related to seminary formation and education at the Beda College, Rome, including Fundamentals of Formation, Community Life, Organizing Formation, Intellectual Formation, Spiritual Formation, Pastoral Formation, and the challenges arising in these fields.

Program X4TOC4 (Version 86-1). Translation of experimental data from the EXFOR format to a computation format

International Nuclear Information System (INIS)

Cullen, D.E.

1986-09-01

Experimental nuclear reaction data are world-wide compiled in EXFOR format. The computer program X4TOC4 described in the present document translates data from the rather flexible EXFOR format to the more rigid ''computation format'' which is suitable for input to further computer processing of the data including graphical plotting. The program is available costfree from the IAEA Nuclear Data Section, upon request. (author)

Creating and maintaining a gas cap in tar sands formations

Science.gov (United States)

Vinegar, Harold J.; Karanikas, John Michael; Dinkoruk, Deniz Sumnu; Wellington, Scott Lee

2010-03-16

Methods for treating a tar sands formation are disclosed herein. Methods for treating a tar sands formation may include providing heat to at least part of a hydrocarbon layer in the formation from one or more heaters located in the formation. Pressure may be allowed to increase in an upper portion of the formation to provide a gas cap in the upper portion. At least some hydrocarbons are produced from a lower portion of the formation.

Dust formation and ionization in novae

International Nuclear Information System (INIS)

Yamamoto, Tetsuo; Sato, Shuji; Nariai, Kyoji.

1979-01-01

In order to explain the fact that some novae show the increase of infrared radiation indicating the formation of circumstellar dust grains while some others do not, the theory that the formation of dust in the circumstellar envelope of a nova depends on the intensity of ultraviolet radiation from a central star has been presented. It is known that the central star of a nova emits radiation at nearly constant rate, and its effective temperature rises. It was concluded that the novae with higher emission than a certain value are the poor candidates for dust formation because the whole envelope is ionized before dust is formed. But this conclusion is misleading. The evolution of the ultraviolet radiation emanating from a central star is summarized. The condensation of grains is possible when the partial pressure of the vapor, from which the grains are formed, becomes higher than the saturation vapor pressure. The temperature of grains can be estimated by equating the radiations absorbed and emitted. The grains evaporate if the grain temperature is higher than the condensation temperature. The formation of a Stroemgren sphere in the exploding envelope of a nova is discussed. For the formation of grains, it is necessary that temperature drops below the condensation temperature before the whole envelope is ionized. Hence dust grains do not grow if the grain temperature at a phase is higher than the condensation temperature. (Kako, I.)

The formation of stellar black holes

Science.gov (United States)

Mirabel, Félix

2017-08-01

It is believed that stellar black holes (BHs) can be formed in two different ways: Either a massive star collapses directly into a BH without a supernova (SN) explosion, or an explosion occurs in a proto-neutron star, but the energy is too low to completely unbind the stellar envelope, and a large fraction of it falls back onto the short-lived neutron star (NS), leading to the delayed formation of a BH. Theoretical models set progenitor masses for BH formation by implosion, namely, by complete or almost complete collapse, but observational evidences have been elusive. Here are reviewed the observational insights on BHs formed by implosion without large natal kicks from: (1) the kinematics in three dimensions of space of five Galactic BH X-ray binaries (BH-XRBs), (2) the diversity of optical and infrared observations of massive stars that collapse in the dark, with no luminous SN explosions, possibly leading to the formation of BHs, and (3) the sources of gravitational waves (GWs) produced by mergers of stellar BHs so far detected with LIGO. Multiple indications of BH formation without ejection of a significant amount of matter and with no natal kicks obtained from these different areas of observational astrophysics, and the recent observational confirmation of the expected dependence of BH formation on metallicity and redshift, are qualitatively consistent with the high merger rates of binary black holes (BBHs) inferred from the first detections with LIGO.

Endogenous leukotriene formation during anaphylactic shock

International Nuclear Information System (INIS)

Keppler, A.; Oerning, L.; Bernstroem, K.; Hammarstroem, S.

1987-01-01

Leukotriene (LT)C 4 is a biologically active substance, presumed to play major roles as a mediator of allergic and anaphylactic reactions. It is formed e.g. by basophilic and eosinophilic leukocytes, monocytes, macrophages, and mast cells. In cells having IgE receptors, bridging of these by divalent anti-IgE-receptor antibodies or by interaction between receptor-bound IgE and anti-IgE will induce LTC 4 formation. Leukotriene formation has also been demonstrated in other in vitro models of immediate hypersensivity. The biological actions of LTC 4 , comprise induction of airway obstruction, constriction of coronary arteries, hypotension, and plasma extravasation. Leukotriene formation in vivo may mediate anaphylactic shock symptoms and cause the death of an animal. In order to prove the presumed mediator role of this substance in anaphylactic reactions, it is necessary to demonstrate its endogenous formation during shock. Studies on the metabolism of LTC 4 have revealed rapid catabolism by various transformations of the peptide substituent. Recently, three metabolites were demonstrated to be excreted as end-products in man (LTE 4 ,) and the rat (N-acetyl LTE 4 and N-acetyl 11-trans LTE 4 ). By monitoring biliary N-acetyl LTE 4 levels, endogenous leukotriene formation in the rat was demonstrated in vivo after tissue trauma and endotoxin shock. We now wish to report evidence for endogenous leukotriene C 4 production during anaphylactic shock in guinea pigs. 37 refs. (author)

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

The formation of ice sails

Science.gov (United States)

Fowler, A. C.; Mayer, C.

2017-11-01

Debris-covered glaciers are prone to the formation of a number of supraglacial geomorphological features, and generally speaking, their upper surfaces are far from level surfaces. Some of these features are due to radiation screening or enhancing properties of the debris cover, but theoretical explanations of the consequent surface forms are in their infancy. In this paper we consider a theoretical model for the formation of "ice sails", which are regularly spaced bare ice features which are found on debris-covered glaciers in the Karakoram.

Nitrate formation during ozonation as a surrogate parameter for abatement of micropollutants and the N-nitrosodimethylamine (NDMA) formation potential.

Science.gov (United States)

Song, Yang; Breider, Florian; Ma, Jun; von Gunten, Urs

2017-10-01

In this study, nitrate formation from ammonium and/or dissolved organic nitrogen (DON) was investigated as a novel surrogate parameter to evaluate the abatement of micropollutants during ozonation of synthetic waters containing natural organic matter (NOM) isolates, a natural water and secondary wastewater effluents. Nitrate formation during ozonation was compared to the changes in UV absorbance at 254 nm (UVA 254 ) including the effect of pH. For low specific ozone doses UVA 254 was abated more efficiently than nitrate was formed. This is due to a relatively slow rate-limiting step for nitrate formation from the reaction between ozone and a proposed nitrogen-containing intermediate. This reaction cannot compete with the fast reactions between ozone and UV-absorbing moieties (e.g., activated aromatic compounds). To further test the kinetics of nitrate formation, two possible intermediates formed during ozonation of DON were tested. At pH 7, nitrate was formed during ozonation of acetone oxime and methyl nitroacetate with second-order rate constants of 256.7 ± 4.7 M -1  s -1 and 149.5 ± 5.8 M -1  s -1 , respectively. The abatement of the selected micropollutants (i.e., 17α-ethinylestradiol (EE2), carbamazepine (CBZ), bezafibrate (BZF), ibuprofen (IBU), and p-chlorobenzoic acid (pCBA)) was investigated for specific ozone doses ≤1.53 mgO 3 /mgDOC and its efficiency depended strongly on the reactivity of the selected compounds with ozone. The relative abatement of micropollutants (i.e., EE2 and CBZ) with high ozone reactivity showed linear relationships with nitrate formation. The abatement of micropollutants with intermediate-low ozone reactivity (BZF, IBU, and pCBA) followed one- and two-phase behaviors relative to nitrate formation during ozonation of water samples containing high and low concentrations of nitrate-forming DON, respectively. During ozonation of a wastewater sample, the N-nitrosodimethylamine formation potential (NDMA-FP) during

THE PSYCHOLOGICAL PECULIARITIES OF THE INFORMATION-COMMUNICATION COMPETENCE FORMATION

Directory of Open Access Journals (Sweden)

Pyannikov Mikhail Mikhailovich

2013-01-01

Full Text Available Informatization of society has significantly changed the paradigm of education, posing the new problems to the scientists. One of such problems is the formation of new conscience – conscience, whose inalienable part is the information culture. The information-communication competence is the basis for the formation of such conscience. In this connection the aim of study is the analysis of psychological peculiarities of the formation of information-communication competence and determination of the role of this personality new formation in conscience of a modern human. The characteristic features of psychological new formations, the stages of cultural development and the role of cultural level of society in the formation of world outlook of a child are studied in this work. In the result of study there was found out the basis of psychic development. The sphere of results application includes the conclusions received in the result of study, which can be used by scholars, who deal with the problem of psychic development of a child. In practice the data of study help to understand better the stages of skill formation and the role of elementary actions in the formation of complex behavioral system.

Relative dynamics and motion control of nanosatellite formation flying

Science.gov (United States)

Pimnoo, Ammarin; Hiraki, Koju

2016-04-01

Orbit selection is a necessary factor in nanosatellite formation mission design/meanwhile, to keep the formation, it is necessary to consume fuel. Therefore, the best orbit design for nanosatellite formation flying should be one that requires the minimum fuel consumption. The purpose of this paper is to analyse orbit selection with respect to the minimum fuel consumption, to provide a convenient way to estimate the fuel consumption for keeping nanosatellite formation flying and to present a simplified method of formation control. The formation structure is disturbed by J2 gravitational perturbation and other perturbing accelerations such as atmospheric drag. First, Gauss' Variation Equations (GVE) are used to estimate the essential ΔV due to the J2 perturbation and atmospheric drag. The essential ΔV presents information on which orbit is good with respect to the minimum fuel consumption. Then, the linear equations which account for J2 gravitational perturbation of Schweighart-Sedwick are presented and used to estimate the fuel consumption to maintain the formation structure. Finally, the relative dynamics motion is presented as well as a simplified motion control of formation structure by using GVE.

Flexible Structure Control Scheme of a UAVs Formation to Improve the Formation Stability During Maneuvers

Directory of Open Access Journals (Sweden)

Kownacki Cezary

2017-09-01

Full Text Available One of the issues related to formation flights, which requires to be still discussed, is the stability of formation flight in turns, where the aerodynamic conditions can be substantially different for outer vehicles due to varying bank angles. Therefore, this paper proposes a decentralized control algorithm based on a leader as the reference point for followers, i.e. other UAVs and two flocking behaviors responsible for local position control, i.e. cohesion and repulsion. But opposite to other research in this area, the structure of the formation becomes flexible (structure is being reshaped and bent according to actual turn radius of the leader. During turns the structure is bent basing on concentred circles with different radiuses corresponding to relative locations of vehicles in the structure. Simultaneously, UAVs' air-speeds must be modified according to the length of turn radius to achieve the stability of the structure. The effectiveness of the algorithm is verified by the results of simulated flights of five UAVs.

ALPINE MAGMATIC-METALLOGENIC FORMATIONS OF THE NORTHWESTERN AND CENTRAL DINARIDES

Directory of Open Access Journals (Sweden)

Jakob Pamić

1997-12-01

Full Text Available In the paper are presented basic geological, petrologieca1, geochemi-cal and mineral deposit data for five main magmatic-metallogenic formations of the northwestern and central Dinarides: (lThe Permo Triassic rifting related andesite-diorite formations; (2 The Jurassic-Lower Cretaceous accretionary (ophiolite formations; (3 The Upper Cretaceous-Paleogene subduction related basalt-rhyohite formations; (4 The Paleogene collisional granite formations, and (5 The Oligo-cene-Neogene postsubduction andesite formations. All these magmatic-metallogenic formations originated in different geotectonic settings during the Alpine evolution of the Dinaridic parts of thc Tethys and the postorogenic evolution of the Paratethys and the Pannonian Basin, respectively.

Thermodynamics and kinetics of vesicles formation processes.

Science.gov (United States)

Guida, Vincenzo

2010-12-15

Vesicles are hollow aggregates, composed of bilayers of amphiphilic molecules, dispersed into and filled with a liquid solvent. These aggregates can be formed either as equilibrium or as out of equilibrium meta-stable structures and they exhibit a rich variety of different morphologies. The surprising richness of structures, the vast range of industrial applications and the presence of vesicles in a number of biological systems have attracted the interest of numerous researchers and scientists. In this article, we review both the thermodynamics and the kinetics aspects of the phenomena of formation of vesicles. We start presenting the thermodynamics of bilayer membranes formation and deformation, with the aim of deriving the conditions for the existence of equilibrium vesicles. Specifically, we use the results from continuum thermodynamics to discuss the possibility of formation of stable equilibrium vesicles, from both mixed amphiphiles and single component systems. We also link the bilayer membrane properties to the molecular structure of the starting amphiphiles. In the second part of this article, we focus on the dynamics and kinetics of vesiculation. We review the process of vesicles formation both from planar lamellar phase under shear and from isotropic micelles. In order to clarify the physical mechanisms of vesicles formation, we continuously draw a parallel between emulsification and vesiculation processes. Specifically, we compare the experimental results, the driving forces and the relative scaling laws identified for the two processes. Describing the dynamics of vesicles formation, we also discuss why non equilibrium vesicles can be formed by kinetics control and why they are meta-stable. Understanding how to control the properties, the stability and the formation process of vesicles is of fundamental importance for a vast number of industrial applications. Copyright © 2009. Published by Elsevier B.V.

Object formation and subject formation: The innovation campus in the Netherlands

NARCIS (Netherlands)

Kooij, H.J.

2015-01-01

A central question within planning theory is how changes between the relations of ‘grand institutions’ such as state, market and education influence the formation of objects ‘on the ground’. Drawing upon Foucault’s work, this article contributes to the understanding of these relations and argues

The early ISM and galaxy formation

Science.gov (United States)

White, Simon D. M.

1990-01-01

Current ideas about galaxy formation are reviewed, with particular attention to when and how it occurred, and what it might have looked like. It is argued that galaxy formation is more recent than originally predicted. Suggestions are presented as to how current observations of distant objects may be interpreted within the cold dark matter theory for the origin of structure.

Atmospheric particle formation in spatially and temporally varying conditions

Energy Technology Data Exchange (ETDEWEB)

Lauros, J.

2011-07-01

Atmospheric particles affect the radiation balance of the Earth and thus the climate. New particle formation from nucleation has been observed in diverse atmospheric conditions but the actual formation path is still unknown. The prevailing conditions can be exploited to evaluate proposed formation mechanisms. This study aims to improve our understanding of new particle formation from the view of atmospheric conditions. The role of atmospheric conditions on particle formation was studied by atmospheric measurements, theoretical model simulations and simulations based on observations. Two separate column models were further developed for aerosol and chemical simulations. Model simulations allowed us to expand the study from local conditions to varying conditions in the atmospheric boundary layer, while the long-term measurements described especially characteristic mean conditions associated with new particle formation. The observations show statistically significant difference in meteorological and back-ground aerosol conditions between observed event and non-event days. New particle formation above boreal forest is associated with strong convective activity, low humidity and low condensation sink. The probability of a particle formation event is predicted by an equation formulated for upper boundary layer conditions. The model simulations call into question if kinetic sulphuric acid induced nucleation is the primary particle formation mechanism in the presence of organic vapours. Simultaneously the simulations show that ignoring spatial and temporal variation in new particle formation studies may lead to faulty conclusions. On the other hand, the theoretical simulations indicate that short-scale variations in temperature and humidity unlikely have a significant effect on mean binary water sulphuric acid nucleation rate. The study emphasizes the significance of mixing and fluxes in particle formation studies, especially in the atmospheric boundary layer. The further

Negative ion formation processes: A general review

International Nuclear Information System (INIS)

Alton, G.D.

1990-01-01

The principal negative ion formation processes will be briefly reviewed. Primary emphasis will be placed on the more efficient and universal processes of charge transfer and secondary ion formation through non-thermodynamic surface ionization. 86 refs., 20 figs

Protostar formation in the early universe.

Science.gov (United States)

Yoshida, Naoki; Omukai, Kazuyuki; Hernquist, Lars

2008-08-01

The nature of the first generation of stars in the universe remains largely unknown. Observations imply the existence of massive primordial stars early in the history of the universe, and the standard theory for the growth of cosmic structure predicts that structures grow hierarchically through gravitational instability. We have developed an ab initio computer simulation of the formation of primordial stars that follows the relevant atomic and molecular processes in a primordial gas in an expanding universe. The results show that primeval density fluctuations left over from the Big Bang can drive the formation of a tiny protostar with a mass 1% that of the Sun. The protostar is a seed for the subsequent formation of a massive primordial star.

Microwave based method of monitoring crack formation

International Nuclear Information System (INIS)

Aman, Sergej; Aman, Alexander; Majcherek, Soeren; Hirsch, Soeren; Schmidt, Bertram

2014-01-01

The formation of cracks in glass particles was monitored by application of linearly polarized microwaves. The breakage behavior of glass spheres coated with a thin gold layer of about 50 nm, i.e. a thickness that is lower than the microwave penetration depth, was tested. In this way the investigation of fracture behavior of electronic circuits was simulated. A shielding current was induced in the gold layer by the application of microwaves. During the crack formation the distribution of this current changed abruptly and a scattered microwave signal appeared at the frequency of the incident microwaves. The time behavior of the scattered signal reflects the microscopic processes occurring during the fracture of the specimen. The duration of the increasing signal corresponds to the crack formation time in the tested specimen. This time was estimated as particle size divided by crack development speed in glass. An intense emission of electrons occurs during the formation of cracks. Due to this, coherent Thomson scattering of microwaves by emitted electrons becomes significant with a delay of a few microseconds after the initial phase of crack formation. In this time the intensity of the microwave signal increases. (paper)

Galaxy formation: internal mechanisms and cosmological processes

International Nuclear Information System (INIS)

Martig, Marie

2010-01-01

This thesis is devoted to galaxy formation and evolution in a cosmological context. Cosmological simulations have unveiled two main modes of galaxy growth: hierarchical growth by mergers and accretion of cold gas from cosmic filaments. However, these simulations rarely take into account small scale mechanisms, that govern internal evolution and that are a key ingredient to understand galaxy formation and evolution. Thanks to a new simulation technique that I have developed, I first studied the colors of galaxies, and in particular the reddening of elliptical galaxies. I showed that the gas disk in an elliptical galaxy could be stabilized against star formation because of the galaxy's stellar component being within a spheroid instead of a disk. This mechanism can explain the red colors of some elliptical galaxies that contain a gas disk. I also studied the formation of spiral galaxies: most cosmological simulations cannot explain the formation of Milky Way-like galaxies, i.e. with a large disk and a small bulge. I showed that this issue could be partly solved by taking into account in the simulations the mass loss from evolved stars through stellar winds, planetary nebulae and supernovae explosions. (author) [fr

Star-formation history of very young clusters

International Nuclear Information System (INIS)

Stahler, S.W.

1985-01-01

The popular idea that star formation has proceeded sequentially from lowest to highest mass members in open clusters is examined critically. For extremely young clusters, such as NGC 2264 and NGC 6530, this sequential hypothesis is a consequence of the assignment of pre-main-sequence contraction ages to all member stars. However, such ages yield a formation history which is implausible from a physical point of view, since the critical time for the onset of formation at any stellar mass is equal to the pre-main-sequence contraction time for that mass. Moreover, these ages are in conflict with the strong observational evidence that a substantial fraction of cluster members have already reached the main sequence. After reconsideration of the probable main-sequence members, the stellar ages in NGC 2264 and NGC 6530 are consistent with a variety of formation histories, and, in particular, with the view that all stellar masses form in approximately the same interval of time within a given cluster, i.e., that there is no mass-age correlation. A notion closely related to the sequential hypothesis, that the total star-formation rate increases exponentially with time, is subject to the same criticism

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.

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.

Inflow of atomic gas fuelling star formation

DEFF Research Database (Denmark)

Michałowski, M. J.; Gentile, G.; Hjorth, Jeppe

2016-01-01

Gamma-ray burst host galaxies are deficient in molecular gas, and show anomalous metal-poor regions close to GRB positions. Using recent Australia Telescope Compact Array (ATCA) Hi observations we show that they have substantial atomic gas reservoirs. This suggests that star formation in these ga......Gamma-ray burst host galaxies are deficient in molecular gas, and show anomalous metal-poor regions close to GRB positions. Using recent Australia Telescope Compact Array (ATCA) Hi observations we show that they have substantial atomic gas reservoirs. This suggests that star formation...... in these galaxies may be fuelled by recent inflow of metal-poor atomic gas. While this process is debated, it can happen in low-metallicity gas near the onset of star formation because gas cooling (necessary for star formation) is faster than the Hi-to-H2 conversion....

Systematization of experiences in the professor formation to integrate the university and the family to the professional formation.

Directory of Open Access Journals (Sweden)

Geycell Emma Guevara Fernández

2012-04-01

Full Text Available The current work presents a systematization of experiences carried out at the University José Martí Pérez of Sancti Spíritus as a modality of participative action research which permitted, from the articulation of theory and practice, to organize the knowledge about family-university relationship and its influence in the professional formation. As a starting point, different diagnostic techniques were applied such as: document analysis, participating observation, auto assessing scales, discussion groups, interviews, survey and the methodological triangulation data which led to the determination of shortages and potentialities that the staff had as to formation to face it. By means of a shared process, the implied actors agreed the execution of actions which supplied the formative needs and led to grow up gradually towards the improvement of a continuing formation for the educative orientation carried out in higher education and where the development social situation of the young university professor demands as a fundamental category.

Distributed formation tracking using local coordinate systems

DEFF Research Database (Denmark)

Yang, Qingkai; Cao, Ming; Garcia de Marina, Hector

2018-01-01

This paper studies the formation tracking problem for multi-agent systems, for which a distributed estimator–controller scheme is designed relying only on the agents’ local coordinate systems such that the centroid of the controlled formation tracks a given trajectory. By introducing a gradient...... descent term into the estimator, the explicit knowledge of the bound of the agents’ speed is not necessary in contrast to existing works, and each agent is able to compute the centroid of the whole formation in finite time. Then, based on the centroid estimation, a distributed control algorithm...

Emissions and dioxins formation from waste incinerators

International Nuclear Information System (INIS)

Carbone, A.I.; Zagaroli, M.

1989-01-01

This paper describes current knowledge on dioxins formation and emission from waste incinerators. The pertinent Italian law and effects on man health are dealt with, too. The picture of existing municipal incinerators is presented concerning both the actual emission levels and the monitored levels in the environment. Sampling and analysis systems of these organic chlorinated micro-pollutants and current theories on precursors, formation mechanisms, and influence of different parameters are also described. The last section deals with some of the techniques that can be used to reduce dioxins formation and emission from municipal incinerators. (author)

Formation and filtration characteristics of solids generated in a high level liquid waste treatment process. Solids formation behavior from simulated high level liquid waste

International Nuclear Information System (INIS)

Kondo, Y.; Kubota, M.

1997-01-01

The solids formation behavior in a simulated high level liquid waste (HLLW) was experimentally examined, when the simulated HLLW was treated in the ordinary way of actual HLLW treatment process. Solids formation conditions and mechanism were closely discussed. The solids formation during a concentration step can be explained by considering the formation of zirconium phosphate, phosphomolybdic acid and precipitation of strontium and barium nitrates and their solubilities. For the solids formation during the denitration step, at least four courses were observed; formation of an undissolved material by a chemical reaction with each other of solute elements (zirconium, molybdenum, tellurium) precipitation by reduction (platinum group metals) formation of hydroxide or carbonate compounds (chromium, neodymium, iron, nickel, strontium, barium) and a physical adsorption to stable solid such as zirconium molybdate (nickel, strontium, barium). (author)

Plasma formation in TBR

International Nuclear Information System (INIS)

Del Bosco, E.

1981-01-01

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 H 2 , 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) [pt

Reconsidering Formative Measurement

Science.gov (United States)

Howell, Roy D.; Breivik, Einar; Wilcox, James B.

2007-01-01

The relationship between observable responses and the latent constructs they are purported to measure has received considerable attention recently, with particular focus on what has become known as formative measurement. This alternative to reflective measurement in the area of theory-testing research is examined in the context of the potential…

Cu(II) promotes amyloid pore formation

International Nuclear Information System (INIS)

Zhang, Hangyu; Rochet, Jean-Christophe; Stanciu, Lia A.

2015-01-01

The aggregation of α-synuclein is associated with dopamine neuron death in Parkinson's disease. There is controversy in the field over the question of which species of the aggregates, fibrils or protofibrils, are toxic. Moreover, compelling evidence suggested the exposure to heavy metals to be a risk of PD. Nevertheless, the mechanism of metal ions in promoting PD remains unclear. In this research, we investigated the structural basis of Cu(II) induced aggregation of α-synuclein. Using transmission electron microscopy experiments, Cu(II) was found to promote in vitro aggregation of α-synuclein by facilitating annular protofibril formation rather than fibril formation. Furthermore, neuroprotective baicalein disaggregated annular protofibrils accompanied by considerable decrease of β-sheet content. These results strongly support the hypothesis that annular protofibrils are the toxic species, rather than fibrils, thereby inspiring us to search novel therapeutic strategies for the suppression of the toxic annular protofibril formation. - Highlights: • Cu(II) promoted the annular protofibril formation of α-synuclein in vitro. • Cu(II) postponed the in vitro fibrillization of α-synuclein. • Neuroprotective baicalein disaggregated annular protofibrils

Cu(II) promotes amyloid pore formation

Energy Technology Data Exchange (ETDEWEB)

Zhang, Hangyu, E-mail: hangyuz@uw.edu [Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN 47907 (United States); Rochet, Jean-Christophe [Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN 47907 (United States); Stanciu, Lia A. [Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN 47907 (United States); School of Materials Engineering, Purdue University, West Lafayette, IN 47907 (United States)

2015-08-14

The aggregation of α-synuclein is associated with dopamine neuron death in Parkinson's disease. There is controversy in the field over the question of which species of the aggregates, fibrils or protofibrils, are toxic. Moreover, compelling evidence suggested the exposure to heavy metals to be a risk of PD. Nevertheless, the mechanism of metal ions in promoting PD remains unclear. In this research, we investigated the structural basis of Cu(II) induced aggregation of α-synuclein. Using transmission electron microscopy experiments, Cu(II) was found to promote in vitro aggregation of α-synuclein by facilitating annular protofibril formation rather than fibril formation. Furthermore, neuroprotective baicalein disaggregated annular protofibrils accompanied by considerable decrease of β-sheet content. These results strongly support the hypothesis that annular protofibrils are the toxic species, rather than fibrils, thereby inspiring us to search novel therapeutic strategies for the suppression of the toxic annular protofibril formation. - Highlights: • Cu(II) promoted the annular protofibril formation of α-synuclein in vitro. • Cu(II) postponed the in vitro fibrillization of α-synuclein. • Neuroprotective baicalein disaggregated annular protofibrils.

Transcriptional regulation of Drosophila gonad formation.

Science.gov (United States)

Tripathy, Ratna; Kunwar, Prabhat S; Sano, Hiroko; Renault, Andrew D

2014-08-15

The formation of the Drosophila embryonic gonad, involving the fusion of clusters of somatic gonadal precursor cells (SGPs) and their ensheathment of germ cells, provides a simple and genetically tractable model for the interplay between cells during organ formation. In a screen for mutants affecting gonad formation we identified a SGP cell autonomous role for Midline (Mid) and Longitudinals lacking (Lola). These transcriptional factors are required for multiple aspects of SGP behaviour including SGP cluster fusion, germ cell ensheathment and gonad compaction. The lola locus encodes more than 25 differentially spliced isoforms and we have identified an isoform specific requirement for lola in the gonad which is distinct from that in nervous system development. Mid and Lola work in parallel in gonad formation and surprisingly Mid overexpression in a lola background leads to additional SGPs at the expense of fat body cells. Our findings support the idea that although the transcription factors required by SGPs can ostensibly be assigned to those being required for either SGP specification or behaviour, they can also interact to impinge on both processes. Copyright © 2014 Elsevier Inc. All rights reserved.

TIME-VARYING DYNAMICAL STAR FORMATION RATE

Energy Technology Data Exchange (ETDEWEB)

Lee, Eve J.; Chang, Philip; Murray, Norman, E-mail: evelee@berkeley.edu [Canadian Institute for Theoretical Astrophysics, 60 St. George Street, University of Toronto, Toronto, ON M5S 3H8 (Canada)

2015-02-10

We present numerical evidence of dynamic star formation in which the accreted stellar mass grows superlinearly with time, roughly as t {sup 2}. We perform simulations of star formation in self-gravitating hydrodynamic and magnetohydrodynamic turbulence that is continuously driven. By turning the self-gravity of the gas in the simulations on or off, we demonstrate that self-gravity is the dominant physical effect setting the mass accretion rate at early times before feedback effects take over, contrary to theories of turbulence-regulated star formation. We find that gravitational collapse steepens the density profile around stars, generating the power-law tail on what is otherwise a lognormal density probability distribution function. Furthermore, we find turbulent velocity profiles to flatten inside collapsing regions, altering the size-line width relation. This local flattening reflects enhancements of turbulent velocity on small scales, as verified by changes to the velocity power spectra. Our results indicate that gas self-gravity dynamically alters both density and velocity structures in clouds, giving rise to a time-varying star formation rate. We find that a substantial fraction of the gas that forms stars arrives via low-density flows, as opposed to accreting through high-density filaments.

Solution mining dawsonite from hydrocarbon containing formations with a chelating agent

Science.gov (United States)

Vinegar, Harold J [Bellaire, TX

2009-07-07

A method for treating an oil shale formation comprising dawsonite includes providing heat from one or more heaters to the formation to heat the formation. Hydrocarbon fluids are produced from the formation. At least some dawsonite in the formation is decomposed with the provided heat. A chelating agent is provided to the formation to dissolve at least some dawsonite decomposition products. The dissolved dawsonite decomposition products are produced from the formation.

Evaluation of anomalies during nickel and titanium silicide formation using the effective heat of formation mode

CSIR Research Space (South Africa)

Pretorius, R

1993-11-01

Full Text Available , as well as the observed sequence of growth of different silicide phases, are not in agree- ment with thermodynamic considerations [26]. In the case of the nickel silicides Ni,Si is nearly always found to be the first... to determine how the oxygen content in the silicon affects phase formation. We also show how the anomalous behaviour of titanium and nickel silicide formation can be explained thermodynamically by using the ?effective heat...

Black-hole-regulated star formation in massive galaxies

Science.gov (United States)

Martín-Navarro, Ignacio; Brodie, Jean P.; Romanowsky, Aaron J.; Ruiz-Lara, Tomás; van de Ven, Glenn

2018-01-01

Supermassive black holes, with masses more than a million times that of the Sun, seem to inhabit the centres of all massive galaxies. Cosmologically motivated theories of galaxy formation require feedback from these supermassive black holes to regulate star formation. In the absence of such feedback, state-of-the-art numerical simulations fail to reproduce the number density and properties of massive galaxies in the local Universe. There is, however, no observational evidence of this strongly coupled coevolution between supermassive black holes and star formation, impeding our understanding of baryonic processes within galaxies. Here we report that the star formation histories of nearby massive galaxies, as measured from their integrated optical spectra, depend on the mass of the central supermassive black hole. Our results indicate that the black-hole mass scales with the gas cooling rate in the early Universe. The subsequent quenching of star formation takes place earlier and more efficiently in galaxies that host higher-mass central black holes. The observed relation between black-hole mass and star formation efficiency applies to all generations of stars formed throughout the life of a galaxy, revealing a continuous interplay between black-hole activity and baryon cooling.

Black-hole-regulated star formation in massive galaxies.

Science.gov (United States)

Martín-Navarro, Ignacio; Brodie, Jean P; Romanowsky, Aaron J; Ruiz-Lara, Tomás; van de Ven, Glenn

2018-01-18

Supermassive black holes, with masses more than a million times that of the Sun, seem to inhabit the centres of all massive galaxies. Cosmologically motivated theories of galaxy formation require feedback from these supermassive black holes to regulate star formation. In the absence of such feedback, state-of-the-art numerical simulations fail to reproduce the number density and properties of massive galaxies in the local Universe. There is, however, no observational evidence of this strongly coupled coevolution between supermassive black holes and star formation, impeding our understanding of baryonic processes within galaxies. Here we report that the star formation histories of nearby massive galaxies, as measured from their integrated optical spectra, depend on the mass of the central supermassive black hole. Our results indicate that the black-hole mass scales with the gas cooling rate in the early Universe. The subsequent quenching of star formation takes place earlier and more efficiently in galaxies that host higher-mass central black holes. The observed relation between black-hole mass and star formation efficiency applies to all generations of stars formed throughout the life of a galaxy, revealing a continuous interplay between black-hole activity and baryon cooling.

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.

THE PSYCHOLOGICAL PECULIARITIES OF THE INFORMATION-COMMUNICATION COMPETENCE FORMATION

Directory of Open Access Journals (Sweden)

Михаил Михайлович Пьянников

2013-04-01

Full Text Available Informatization of society has significantly changed the paradigm of education, posing the new problems to the scientists. One of such problems is the formation of new conscience – conscience, whose inalienable part is the information culture. The information-communication competence is the basis for the formation of such conscience. In this connection the aim of study is the analysis of psychological peculiarities of the formation of information-communication competence and determination of the role of this personality new formation in conscience of a modern human. The characteristic features of psychological new formations, the stages of cultural development and the role of cultural level of society in the formation of world outlook of a child are studied in this work. In the result of study there was found out the basis of psychic development. The sphere of results application includes the conclusions received in the result of study, which can be used by scholars, who deal with the problem of psychic development of a child. In practice the data of study help to understand better the stages of skill formation and the role of elementary actions in the formation of complex behavioral system.DOI: http://dx.doi.org/10.12731/2218-7405-2013-1-33

Hydrogen or formate: Alternative key players in methanogenic degradation.

Science.gov (United States)

Schink, Bernhard; Montag, Dominik; Keller, Anja; Müller, Nicolai

2017-06-01

Hydrogen and formate are important electron carriers in methanogenic degradation in anoxic environments such as sediments, sewage sludge digestors and biogas reactors. Especially in the terminal steps of methanogenesis, they determine the energy budgets of secondary (syntrophically) fermenting bacteria and their methanogenic partners. The literature provides considerable data on hydrogen pool sizes in such habitats, but little data exist for formate concentrations due to technical difficulties in formate determination at low concentration. Recent evidence from biochemical and molecular biological studies indicates that several secondary fermenters can use both hydrogen and formate for electron release, and may do so even simultaneously. Numerous strictly anaerobic bacteria contain enzymes which equilibrate hydrogen and formate pools to energetically equal values, and recent measurements in sewage digestors and biogas reactors indicate that - beyond occasional fluctuations - the pool sizes of hydrogen and formate are indeed energetically nearly equivalent. Nonetheless, a thermophilic archaeon from a submarine hydrothermal vent, Thermococcus onnurineus, can obtain ATP from the conversion of formate to hydrogen plus bicarbonate at 80°C, indicating that at least in this extreme environment the pools of formate and hydrogen are likely to be sufficiently different to support such an unusual type of energy conservation. © 2017 Society for Applied Microbiology and John Wiley & Sons Ltd.

Cosmology and galaxy formation

International Nuclear Information System (INIS)

Rees, M.J.

1977-01-01

Implications of the massive halos and ''missing mass'' for galaxy formation are addressed; it is suggested that this mass consists of ''Population III'' stars that formed before the galaxies did. 19 references

Qualitative analysis of the e-cloud formation

International Nuclear Information System (INIS)

Heifets, Samuel A

2002-01-01

The qualitative analysis of the electron cloud formation is presented. Two mechanisms of the cloud formation, generation of jets of primary photo-electrons and thermalization of electrons in the electron cloud, are analyzed and compared with simulations for the NLC damping ring [1

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

QUESTION FORMATION OF BAHASA INDONESIA AS A SECOND LANGUAGE

Directory of Open Access Journals (Sweden)

zulfa Sakhiyya

2013-07-01

Full Text Available Abstract: This article aims to implement Processability Theory (PT to Bahasa Indonesia or Indonesian language and to identify developmental stages for question formation in the setting of Bahasa Indonesia as a second language (ISL. PT provides a theoretical framework in making predictions about the course of language development, in this case the question formation acquisition. This study proposes developmental stages of question formation in ISL setting by contrasting the lexical functional grammar of Indonesian question as compared to ESL question formation. Four stages of ISL question formation were proposed. The proposed stages serve as the basis for data analysis and to show its plausibility.

The Role of Emotions in Delusion Formation

Directory of Open Access Journals (Sweden)

Smurzyńska Adrianna

2016-12-01

Full Text Available The text concerns the role of emotions in delusion formation. Provided are definitions from DSM-V and DSM-IV-R and the problems found in those definitions. One of them, the problem of delusion formation, is described when providing cognitive theories of delusions. The core of the paper is a presentation of the emotional and affective disorders in delusions, especially Capgras delusion and Cotard delusion. The author provides a comparison of the kinds of delusions and the conclusions taken from neuroimaging studies. As a result of the fact that an explanation of delusion formation focusing on emotional problems turns out to be insufficient, the author provides examples of the reasoning impairments which coexist with them. At the end of the article, some hypotheses are proposed concerning the role of emotions and reasoning in delusion formation and the relation between belief disorders and emotional disorders.

Formation of soap bubbles by gas jet

Science.gov (United States)

Zhou, Maolei; Li, Min; Chen, Zhiyuan; Han, Jifeng; Liu, Dong

2017-12-01

Soap bubbles can be easily generated by various methods, while their formation process is complicated and still worth studying. A model about the bubble formation process was proposed in the study by Salkin et al. [Phys. Rev. Lett. 116, 077801 (2016)] recently, and it was reported that the bubbles were formed when the gas blowing velocity was above one threshold. However, after a detailed study of these experiments, we found that the bubbles could be generated in two velocity ranges which corresponded to the laminar and turbulent gas jet, respectively, and the predicted threshold was only effective for turbulent gas flow. The study revealed that the bubble formation was greatly influenced by the aerodynamics of the gas jet blowing to the film, and these results will help to further understand the formation mechanism of the soap bubble as well as the interaction between the gas jet and the thin liquid film.

Bonded exciplex formation: electronic and stereoelectronic effects.

Science.gov (United States)

Wang, Yingsheng; Haze, Olesya; Dinnocenzo, Joseph P; Farid, Samir; Farid, Ramy S; Gould, Ian R

2008-12-18

As recently proposed, the singlet-excited states of several cyanoaromatics react with pyridine via bonded-exciplex formation, a novel concept in photochemical charge transfer reactions. Presented here are electronic and steric effects on the quenching rate constants, which provide valuable support for the model. Additionally, excited-state quenching in poly(vinylpyridine) is strongly inhibited both relative to that in neat pyridine and also to conventional exciplex formation in polymers, consistent with a restrictive orientational requirement for the formation of bonded exciplexes. Examples of competing reactions to form both conventional and bonded exciplexes are presented, which illustrate the delicate balance between these two processes when their reaction energetics are similar. Experimental and computational evidence is provided for the formation of a bonded exciplex in the reaction of the singlet excited state of 2,6,9,10-tetracyanoanthracene (TCA) with an oxygen-substituted donor, dioxane, thus expanding the scope of bonded exciplexes.

Complexity and formative experiences

Directory of Open Access Journals (Sweden)

Roque Strieder

2017-12-01

Full Text Available The contemporaneity is characterized by instability and diversity calling into question certainties and truths proposed in modernity. We recognize that the reality of things and phenomena become effective as a set of events, interactions, retroactions and chances. This different frame extends the need for revision of the epistemological foundations that sustain educational practices and give them sense. The complex thinking is an alternative option for acting as a counterpoint to classical science and its reductionist logic and knowledge compartmentalization, as well as to answer to contemporary epistemological and educational challenges. It aims to associate different areas and forms of knowledge, without, however merge them, distinguishing without separating the several disciplines and instances of the realities. This study, in theoretical references, highlights the relevance of complex approaches to support formative experiences because also able to produce complexities in reflections about educational issues. We conclude that formative possibilities from complexity potentialize the resignification of human’s conception and the understanding of its singularity in interdependence; The understanding that pedagogical and educational activities is a constant interrogation about the possibilities of knowing the knowledge and reframe learning, far beyond knowing its functions and utilitarian purposes; and, as a formative possibility, places us on the trail of responsibility, not as something eventual, but present and indicative of freedom to choose to stay or go beyond.

The role of chloramine species in NDMA formation.

Science.gov (United States)

Selbes, Meric; Beita-Sandí, Wilson; Kim, Daekyun; Karanfil, Tanju

2018-09-01

N-nitrosodimethylamine (NDMA), a probable human carcinogen disinfection by-product, has been detected in chloraminated drinking water systems. Understanding its formation over time is important to control NDMA levels in distribution systems. The main objectives of this study were to investigate the role of chloramine species (i.e., monochloramine and dichloramine); and the factors such as pH, sulfate, and natural organic matter (NOM) influencing the formation of NDMA. Five NDMA precursors (i.e., dimethylamine (DMA), trimethylamine (TMA), N,N-dimethylisopropylamine (DMiPA), N,N-dimethylbenzylamine (DMBzA), and ranitidine (RNTD)) were carefully selected based on their chemical structures and exposed to varying ratios of monochloramine and dichloramine. All amine precursors reacted relatively fast to form NDMA and reached their maximum NDMA yields within 24 h in the presence of excess levels of chloramines (both mono- and dichloramine) or excess levels of dichloramine conditions (with limited monochloramine). When the formation of dichloramine was suppressed (i.e., only monochloramine existed in the system) over the 5 day contact time, NDMA formation from DMA, TMA, and DMiPA was drastically reduced (∼0%). Under monochloramine abundant conditions, however, DMBzA and RNTD showed 40% and 90% NDMA conversions at the end of 5 day contact time, respectively, with slow formation rates, indicating that while these amine precursors react preferentially with dichloramine to form NDMA, they can also react with monochloramine in the absence of dichloramine. NOM and pH influenced dichloramine levels that affected NDMA yields. NOM had an adverse effect on NDMA formation as it created a competition with NDMA precursors for dichloramine. Sulfate did not increase the NDMA formation from the two selected NDMA precursors. pH played a key role as it influenced both chloramine speciation and protonation state of amine precursors and the highest NDMA formation was observed at the p

Paleoenvironments, δ13C and δ18O signatures in the Neoproterozoic carbonates of the Comba Basin, Republic of Congo: Implications for regional correlations and Marinoan event

Science.gov (United States)

Préat, Alain; Delpomdor, Franck; Ackouala Mfere, Anna Perla; Callec, Yannick

2018-01-01

The Ediacaran Schisto-Calcaire Group is a ∼1300 m-thick succession belonging to the West Congo Supergroup in Central Africa. In the Comba Basin, it consists of three carbonate-dominated units defined as formations (SCI to SCIII) that are unconformably overlain by clastic deposits (Mpioka Group) interpreted as a molassic formation associated with the Panafrican Orogen. The underlying Upper Tillite and Cap Carbonate (SCIa) units, considered as markers of the Snowball Earth event were studied in three sections. We investigated the carbonates of the Schisto-Calcaire Group by defining new microfacies (MF1-MF7) and we performed C and O isotopic analyses in order to constraint the depositional and diagenetic events directly after the Marinoan interval. Stratigraphic variations of the stable isotopes are important in the series with lighter δ18O values (>1.5‰) than those of the Neoproterozoic ocean in the SCIc unit. According to regional stratigraphy a temperature effect can be dismissed and a freshwater surface layer is the origin of such negative δ18O values in this unit. The negative δ13C anomaly (-3.5‰ on average) of the Cap Carbonate is similarly to the δ18O values (-6.4‰ on average) in the range of the marine domain during postglacial sea level rise. The sample suite as a whole (SCII and SCIII formations) displays heavier δ18O and δ13C than those of the lower part (SCI unit) of the Schisto-Calcaire Group. The comparison with the Lower Congo (Democratic Republic of Congo) and Nyanga (Gabon) basins shows that the meteoric flushing in SCIc unit of the Schisto-Calcaire Group was regional and not local, and could be derived from a climatic evolution. Although an overall overprint is present, our isotopic relationships argue against overall diagenetic resetting of primary compositions and suggest that with careful examination combined with detailed petrographic analysis general depositional and diagenetic controls can be discerned in oxygen and carbon

On the formation of ball lightning

International Nuclear Information System (INIS)

Silberg, P.A.

1981-01-01

A plasma continuum model for the formation of ball lightning is developed based on a substantial number of reports that the ball is often in the discharge column of a previous lightning stroke. The usual method of setting up the plasma equation for a one-component electron plasma is used. An approximate equation for the plasma is derived from the describing equation which is then solved exactly in terms of the Jacobi elliptic functions. The formation of the ball is based on a nonlinearity of the plasma equation which uner certain circumstances permits the field to collapse into a small region. This collapse is interpreted to be ball lightning. The approximate equation derived for the plasma has the same form as a previous equation used to describe the formation of the fireball plasma. (author)

Forced migration, adolescence, and identity formation.

Science.gov (United States)

Anagnostopoulos, Dimitris C; Vlassopoulos, Maria; Lazaratou, Helen

2006-09-01

Adolescence is a complex biopsychosocial phenomenon. All the inner-subjective changes in adolescents take place within the context of a specific social environment, which offers the necessary ideological setting that adolescents must confront in the course of their identity formation. Forced migration creates conditions under which the adolescent Ego may be traumatized more easily, resulting in the development of defensive mechanisms, which may interfere with the natural process of identity formation. The aim of this paper is to investigate how a traumatic situation such as forced migration may affect the mechanisms of identity formation in adolescence. For this purpose, clinical material, consisting of two cases of psychoanalytical psychotherapy of adolescents who were forced to immigrate to Greece, is presented and discussed in a psychoanalytical theoretical framework, along with the historical-sociological background.

String cavitation formation inside fuel injectors

Science.gov (United States)

Reid, B. A.; Gavaises, M.; Mitroglou, N.; Hargrave, G. K.; Garner, C. P.; McDavid, R. M.

2015-12-01

The formation of vortex or ‘string’ cavitation has been visualised at pressures up to 2000 bar in an automotive-sized optical diesel fuel injector nozzle. The multi-hole nozzle geometry studied allowed observation of the hole-to-hole vortex interaction and, in particular, that of a bridging vortex in the sac region between the holes. Above a threshold Reynolds number, their formation and appearance during a 2 ms injection event was repeatable and independent of upstream pressure and cavitation number. In addition, two different hole layouts and threedimensional flow simulations have been employed to describe how, the relative positions of adjacent holes influenced the formation and hole-to-hole interaction of the observed string cavitation vortices, with good agreement between the experimental and simulation results being achieved.

New concepts in the abstract format of the Compositional Interchange Format

NARCIS (Netherlands)

D.A. van Beek; P.J. Collins (Pieter); D.E. Nadales Agut; J.E. Rooda (Jacobus); R.R.H. Schiffelers; A. Giua; M. Silva (Manuel); J. Zaytoon

2009-01-01

textabstractThe compositional interchange format for hybrid systems (CIF) supports inter-operability of a wide range of tools by means of model transformations to and from the CIF. Work on the CIF takes place in the FP7 Multiform project, and in several other European projects. The CIF consists of

Smectite formation in the presence of sulfuric acid: Implications for acidic smectite formation on early Mars

Science.gov (United States)

Peretyazhko, T. S.; Niles, P. B.; Sutter, B.; Morris, R. V.; Agresti, D. G.; Le, L.; Ming, D. W.

2018-01-01

The excess of orbital detection of smectite deposits compared to carbonate deposits on the martian surface presents an enigma because smectite and carbonate formations are both favored alteration products of basalt under neutral to alkaline conditions. We propose that Mars experienced acidic events caused by sulfuric acid (H2SO4) that permitted phyllosilicate, but inhibited carbonate, formation. To experimentally verify this hypothesis, we report the first synthesis of smectite from Mars-analogue glass-rich basalt simulant (66 wt% glass, 32 wt% olivine, 2 wt% chromite) in the presence of H2SO4 under hydrothermal conditions (∼200 °C). Smectites were analyzed by X-ray diffraction, Mössbauer spectroscopy, visible and near-infrared reflectance spectroscopy and electron microprobe to characterize mineralogy and chemical composition. Solution chemistry was determined by Inductively Coupled Plasma Mass Spectrometry. Basalt simulant suspensions in 11-42 mM H2SO4 were acidic with pH ≤ 2 at the beginning of incubation and varied from acidic (pH 1.8) to mildly alkaline (pH 8.4) at the end of incubation. Alteration of glass phase during reaction of the basalt simulant with H2SO4 led to formation of the dioctahedral smectite at final pH ∼3 and trioctahedral smectite saponite at final pH ∼4 and higher. Anhydrite and hematite formed in the final pH range from 1.8 to 8.4 while natroalunite was detected at pH 1.8. Hematite was precipitated as a result of oxidative dissolution of olivine present in Adirondack basalt simulant. Formation of secondary phases, including smectite, resulted in release of variable amounts of Si, Mg, Na and Ca while solubilization of Al and Fe was low. Comparison of mineralogical and solution chemistry data indicated that the type of smectite (i.e., dioctahedral vs trioctahedral) was likely controlled by Mg leaching from altering basalt and substantial Mg loss created favorable conditions for formation of dioctahedral smectite. We present a model

ON STAR FORMATION RATES AND STAR FORMATION HISTORIES OF GALAXIES OUT TO z ∼ 3

International Nuclear Information System (INIS)

Wuyts, Stijn; Foerster Schreiber, Natascha M.; Lutz, Dieter; Nordon, Raanan; Berta, Stefano; Genzel, Reinhard; Magnelli, Benjamin; Poglitsch, Albrecht; Altieri, Bruno; Andreani, Paola; Aussel, Herve; Daddi, Emanuele; Elbaz, David; Bongiovanni, Angel; Cepa, Jordi; Garcia, Ana Perez; Cimatti, Andrea; Koekemoer, Anton M.; Maiolino, Roberto; McGrath, Elizabeth J.

2011-01-01

We compare multi-wavelength star formation rate (SFR) indicators out to z ∼ 3 in the GOODS-South field. Our analysis uniquely combines U to 8 μm photometry from FIREWORKS, MIPS 24 μm and PACS 70, 100, and 160 μm photometry from the PEP, and Hα spectroscopy from the SINS survey. We describe a set of conversions that lead to a continuity across SFR indicators. A luminosity-independent conversion from 24 μm to total infrared luminosity yields estimates of L IR that are in the median consistent with the L IR derived from PACS photometry, albeit with significant scatter. Dust correction methods perform well at low-to-intermediate levels of star formation. They fail to recover the total amount of star formation in systems with large SFR IR /SFR UV ratios, typically occuring at the highest SFRs (SFR UV+ I R ∼> 100 M sun yr -1 ) and redshifts (z ∼> 2.5) probed. Finally, we confirm that Hα-based SFRs at 1.5 SED and SFR UV+IR provided extra attenuation toward H II regions is taken into account (A V,neb = A V,continuum /0.44). With the cross-calibrated SFR indicators in hand, we perform a consistency check on the star formation histories inferred from spectral energy distribution (SED) modeling. We compare the observed SFR-M relations and mass functions at a range of redshifts to equivalents that are computed by evolving lower redshift galaxies backward in time. We find evidence for underestimated stellar ages when no stringent constraints on formation epoch are applied in SED modeling. We demonstrate how resolved SED modeling, or alternatively deep UV data, may help to overcome this bias. The age bias is most severe for galaxies with young stellar populations and reduces toward older systems. Finally, our analysis suggests that SFHs typically vary on timescales that are long (at least several 100 Myr) compared to the galaxies' dynamical time.

Harnessing Collaborative Annotations on Online Formative Assessments

Science.gov (United States)

Lin, Jian-Wei; Lai, Yuan-Cheng

2013-01-01

This paper harnesses collaborative annotations by students as learning feedback on online formative assessments to improve the learning achievements of students. Through the developed Web platform, students can conduct formative assessments, collaboratively annotate, and review historical records in a convenient way, while teachers can generate…

Cellular chain formation in Escherichia coli biofilms

DEFF Research Database (Denmark)

Vejborg, Rebecca Munk; Klemm, Per

2009-01-01

; 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...

Program PLOTC4 (Version 86-1). Plot evaluated data from the ENDF/B format and/or experimental data which is in a computation format

International Nuclear Information System (INIS)

Cullen, D.E.

1986-09-01

Experimental and evaluated nuclear reaction data are world-wide compiled in EXFOR format and ENDF format, respectively. The computer program PLOTC4 described in the present document plots data from both formats; EXFOR data must be converted first to a ''computation format''. The program is available costfree from the IAEA Nuclear Data Section, upon request. (author)

Carbon nanotube formation by laser direct writing

International Nuclear Information System (INIS)

Wu, Y.-T.; Su, H.-C.; Tsai, C.-M.; Liu, K.-L.; Chen, G.-D.; Huang, R.-H.; Yew, T.-R.

2008-01-01

This letter presents carbon nanotube (CNT) formation by laser direct writing using 248 nm KrF excimer pulsed laser in air at room temperature, which was applied to irradiate amorphous carbon (a-C) assisted by Ni catalysts underneath for the transformation of carbon species into CNTs. The CNTs were synthesized under appropriate combination of laser energy density and a-C thickness. The growth mechanism and key parameters to determine the success of CNT formation were also discussed. The demonstration of the CNT growth by laser direct writing in air at room temperature opens an opportunity of in-position CNT formation at low temperatures

Formation of nuclear security culture in Ukraine

International Nuclear Information System (INIS)

Gavrilyuk, V.Yi.; Gavrilyuk-Burakova, A.V.; Drapej, S.S.; Parkhomenko, V.V.; Proskuryin, D.V.; Romanova, O.P.

2014-01-01

Issues of nuclear security culture formation are considered in the article. Information on establishing and activity of Working Group for formation and development of nuclear security culture being held during 2010 - 2013 is given. An issue of regulation of activity on formation and development of nuclear security culture is illustrated. Analysis of the survey results regarding efficiency assessment of the work aimed to form and develop of nuclear security culture of nuclear facilities is carried out. The results show that the nuclear security culture of the most of nuclear facilities in Ukraine has been formed and is at the stage of development

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...

Formation of adduct of cerium (4) thenoyltrifluoroacetonate

International Nuclear Information System (INIS)

Anyfrieva, S.I.; Polyakova, G.V.; Snezhko, N.I.; Pechurova, N.I.; Martynenko, L.I.; Spitsyn, V.I.

1981-01-01

Adduct formation of thenoyltrifluoroacetonate of Ce(4) [Ce(TTFA) 4 ] with seven nitrogen- and oxygen-containing donor additional ligands is studied using the methods of IR-spectroscopy, derivatography, X-ray phase analysis. The presence of formation of Ce(TTFA) 4 adducts with phosphorus-containing additional ligands tributyl phosphate (TBP), trioctylphosphine oxide (TOPO), triphenylphosphine oxide (TPPO); α, α'-dipyridyl (Dipy) and o-phenanthroline (Phen) is established. The adduct Ce(TTFA) 4 stable to reduction is formed with Dipy, and in the case of Phen, TBP, TOPO, TPPO in the process of adduct formation the reduction of Ce(4) to Ce(3) takes place [ru

Update to the R33 cross section file format

International Nuclear Information System (INIS)

Vickridge, I.C.

2003-01-01

In September 1991, in response to the workshop on cross sections for Ion Beam Analysis (IBA) held in Namur (July 1991, Nuclear Instruments and Methods B66(1992)), a simple ascii format was proposed to facilitate transfer and collation of nuclear reaction cross section data for Ion Beam Analysis (IBA) and especially for Nuclear Reaction Analysis (NRA). Although intended only as a discussion document, the ascii format - referred to as the R33 (Report 33) format - has become a de facto standard. In the decade since this first proposal there have been spectacular advances in computing power and in software usability, however the cross-platform compatibility of the ascii character set has ensured that the need for an ascii format remains. Nuclear reaction cross section data for Nuclear Reaction analysis has been collected and archived on internet web sites over the last decade. This data has largely been entered in the R33 format, although there is a series of elastic cross sections that are expressed as the ratio to the corresponding Rutherford cross sections that have been entered in a format referred to as RTR (ratio to Rutherford). During this time the R33 format has been modified and added to - firstly to take into account angular distributions, which were not catered for in the first proposal, and more recently to cater for elastic cross sections expressed as the ratio-to- Rutherford, which it is useful to have for some elastic scattering programs. It is thus timely to formally update the R33 format. There also exists the large nuclear cross section data collections of the Nuclear Data Network - of which the core centres are the OECD NEA Nuclear Data Bank, the IAEA Nuclear Data Section, the Brookhaven National Laboratory National Nuclear Data Centre and CJD IPPE Obninsk, Russia. The R33 format is now proposed to become a legal computational format for the NDN. It is thus also necessary to provide an updated formal definition of the R33 format in order to provide

Adolescent Violent Victimization and Precocious Union Formation*

Science.gov (United States)

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

2013-01-01

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. PMID:24431471

THE BLACK HOLE FORMATION PROBABILITY

International Nuclear Information System (INIS)

Clausen, Drew; Piro, Anthony L.; Ott, Christian D.

2015-01-01

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

The Black Hole Formation Probability

Science.gov (United States)

Clausen, Drew; Piro, Anthony L.; Ott, Christian D.

2015-02-01

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.

Formation control of unicycle robots using virtual structure approach

NARCIS (Netherlands)

Sadowska, A.D.; Huijberts, H.J.C.; Kostic, D.; Wouw, van de N.; Nijmeijer, H.

2011-01-01

This paper addresses the problem of formation control of groups of unicycle robots with possibly time-varying formation shapes. To solve the problem, we propose two simple distributed formation control algorithms based on the virtual structure approach. We prove exponential convergence of error

ENDF/X: an Extended ENDF Format (Evolution, not Revolution)

International Nuclear Information System (INIS)

Cullen, Dermott E.

2012-01-01

Recently there has been yet another round of complaints about the ENDF format not being modern and general enough to handle today's nuclear data. This has led to suggestions to abandon the current ENDF and move on to a new format. The complaints I hear I fear are based upon not understanding the primary purpose of ENDF and a lack of experience in using the ENDF format and not being flexible to enough to deal with the current format. Personally I do not think that any changes to the ENDF format are Necessary. But here I address the complaints that I have recently heard about the limitations of the ENDF format, and I suggest minor changes that will completely handle these complaints. In turn I would ask those who are complaining and feel that extensions are needed Please give us some examples where these extensions are Needed. Personally I am not aware of any such data, but I am keeping an open mind and I would love to see examples that really Require extensions. I propose a few fairly simple extensions to the current ENDF/B format; what I call ENDF/X. Compared to other suggested revolutionary changes, my evolutionary approach has the advantage that it maintains compatibility with the existing ENDF/B format that we have used successfully for almost fifty years, and still allows the format to be extended for use with other types of data. In addition to my suggested changes to the ENDF/B format I also include a brief history of ENDF/B, in the hope that the experience we have gained over the last almost 50 years will be of help to the present generation of nuclear data developers and users. Please let's not make the mistake of learning nothing from history. Lastly I finish by identifying what I see as the weak point in the current infrastructure that we use to handle evaluated nuclear data; it me it is not the format of the data. (author)

Star formation properties of galaxy cluster A1767

International Nuclear Information System (INIS)

Yan, Peng-Fei; Li, Feng; Yuan, Qi-Rong

2015-01-01

Abell 1767 is a dynamically relaxed, cD cluster of galaxies with a redshift of 0.0703. Among 250 spectroscopically confirmed member galaxies within a projected radius of 2.5r 200 , 243 galaxies (∼ 97%) are spectroscopically covered by the Sloan Digital Sky Survey. Based on this homogeneous spectral sample, the stellar evolutionary synthesis code STARLIGHT is applied to investigate the stellar populations and star formation histories of galaxies in this cluster. The star formation properties of galaxies, such as mean stellar ages, metallicities, stellar masses, and star formation rates, are presented as functions of local galaxy density. A strong environmental effect is found such that massive galaxies in the high-density core region of the cluster tend to have higher metallicities, older mean stellar ages, and lower specific star formation rates (SSFRs), and their recent star formation activities have been remarkably suppressed. In addition, the correlations of the metallicity and SSFR with stellar mass are confirmed. (paper)

Search for Formation Criteria for Globular Cluster Systems

Science.gov (United States)

Nuritdinov, S. N.; Mirtadjieva, K. T.; Tadjibaev, I. U.

2005-01-01

Star cluster formation is a major mode of star formation in the extreme conditions of interacting galaxies and violent starbursts. By studying ages and metallicities of young metal-enhanced star clusters in mergers / merger remnants we can learn about the violent star formation history of these galaxies and eventually about galaxy formation and evolution. We will present a new set of evolutionary synthesis models of our GALEV code specially developed to account for the gaseous emission of presently forming star clusters and an advanced tool to compare large model grids with multi-color broad-band observations becoming presently available in large amounts. Such observations are an ecomonic way to determine the parameters of young star clusters as will be shown in the presentation. First results of newly-born clusters in mergers and starburst galaxies are presented and compared to the well-studied old globulars and interpreted in the framework of galaxy formation / evolution.

A theory of biological pattern formation

OpenAIRE

Gierer, Alfred; Meinhardt, H.

2006-01-01

The paper addresses the formation of striking patterns within originally near-homogenous tissue, the process prototypical for embryology, and represented in particularly puristic form by cut sections of hydra regenerating a complete animal with head and foot. Essential requirements are autocatalytic, self-enhancing activation, combined with inhibitory or depletion effects of wider range - “lateral inhibition”. Not only de-novo-pattern formation, but also well known, striking features of devel...

The GEOLOGY of GÖKÇEADA (ÇANAKKALE

Directory of Open Access Journals (Sweden)

Ramazan SARI

2015-10-01

Full Text Available The geology and especially the magmatic rocks of Gökçeada, which is the biggest island of Turkey and located at 20 km’s west of Biga Peninsula, constitute the subject of this study. Late Ediacaran/Early Paleozoic aged Çamlıca metamorphics which crop out with a tectonic uplift in a narrow area in northwest of Gökçeada are the oldest rocks of the island. Early Eocene aged Karaağaç Formation which is formed by submarine fan deposits unconformably overlies Çamlıca metamorphics. As for the Dağiçitepe volcanic member which is formed by rhyolitic lavas, tuff and tuffites emplaced into Karaağaç Formation cutting Çamlıca metamorphics is the oldest volcanic unit of the study area. On Karaağaç Formation, Koyunbaba Formation has unconformably been deposited which consists of Middle Eocene shallow marine sediments. Then it has conformably been overlain by Soğucak Formation which consists of SE-NW ex- tending reefal limestone. Middle-Upper Eocene aged Ceylan Formation which conformably overlies the Soğucak Formation and the early Oligocene aged Mezardere Formation which conformably overlies Ceylan Formation have been deposited due to turbiditic currents in deep marine environment. Late Eocene(? – Oligocene aged subvolcanics which cut Me- sozoic and Eocene units and emplaced into Eocene aged sedimentary units in the form of crypto dome and dome form the recent rigid topography of the study area and are the second magmatic phase called the “Gökçeada Domes”. Diorite-monzonites porphyry which crys- tallized in lower zones of subvolcanics on the other hand constitutes Mutludere intrusion. In eastern and southern parts of Gökçeada, Late Oligocene Gökçeada ignimbrites are located which are observed in the form of pumice flows on Mezardere Formation. These ignimbrites are then overlain by Early Miocene aged Kesmekaya volcanics which are formed by blocky ash flows. Middle Miocene aged Eşelek volcanics consisting of lava and

Formation of coronal cavities

International Nuclear Information System (INIS)

An, C.H.; Suess, S.T.; Tandberg-Hanssen, E.; Steinolfson, R.S.

1986-01-01

A theoretical study of the formation of a coronal cavity and its relation to a quiescent prominence is presented. It is argued that the formation of a cavity is initiated by the condensation of plasma which is trapped by the coronal magnetic field in a closed streamer and which then flows down to the chromosphere along the field lines due to lack of stable magnetic support against gravity. The existence of a coronal cavity depends on the coronal magnetic field strength; with low strength, the plasma density is not high enough for condensation to occur. Furthermore, we suggest that prominence and cavity material is supplied from the chromospheric level. Whether a coronal cavity and a prominence coexist depends on the magnetic field configuration; a prominence requires stable magnetic support

Radiation induced formation of giant cells (Saccharomyces uvarum). Pt. 1

Energy Technology Data Exchange (ETDEWEB)

Baumstark-Khan, C; Schnitzler, L; Rink, H

1984-02-01

X-irradiated yeast cells (Saccharomyces uvarum) grown in liquid media stop mitosis and form giant cells. Chitin ring formation, being a prerequisite for cell separation, was studied by fluorescence microscopy using Calcofluor White, a chitin specific dye. Experiments with inhibitors of DNA synthesis (hydroxyurea) and chitin synthesis (polyoxin D) demonstrate chitin ring formation to be dependent on DNA synthesis, whereas bud formation is independent of DNA synthesis and chitin ring formation respectively. Basing on these results the formation of X-ray induced giant cells implies one DNA replication which in turn induces the formation of only one chitin ring between mother cell and giant bud. Obviously no septum can be formed. Thus cell separation does not occur, but the bud already formed, produces another bud demonstrating that bud formation itself is independent of DNA synthesis.

Using an ACTIVE teaching format versus a standard lecture format for increasing resident interaction and knowledge achievement during noon conference: a prospective, controlled study

Science.gov (United States)

2014-01-01

Background The traditional lecture is used by many residency programs to fulfill the mandate for regular didactic sessions, despite limited evidence to demonstrate its effectiveness. Active teaching strategies have shown promise in improving medical knowledge but have been challenging to implement within the constraints of residency training. We developed and evaluated an innovative structured format for interactive teaching within the residency noon conference. Methods We developed an ACTIVE teaching format structured around the following steps: assemble (A) into groups, convey (C) learning objectives, teach (T) background information, inquire (I) through cases and questions, verify (V) understanding, and explain (E) answer choices and educate on the learning points. We conducted a prospective, controlled study of the ACTIVE teaching format versus the standard lecture format, comparing resident satisfaction, immediate knowledge achievement and long-term knowledge retention. We qualitatively assessed participating faculty members’ perspectives on the faculty development efforts and the feasibility of teaching using the ACTIVE format. Results Sixty-nine internal medicine residents participated in the study. Overall, there was an improvement in perceived engagement using the ACTIVE teaching format (4.78 vs. 3.80, P teaching format (overall absolute score increase of 11%, P = 0.04) and a trend toward improvement in long-term knowledge retention. Faculty members felt adequately prepared to use the ACTIVE teaching format, and enjoyed teaching with the ACTIVE teaching format more than the standard lecture. Conclusions A structured ACTIVE teaching format improved resident engagement and initial knowledge, and required minimal resources. The ACTIVE teaching format offers an exciting alternative to the standard lecture for resident noon conference and is easy to implement. PMID:24985781

A Decentralized Approach to Formation Flight Routing

NARCIS (Netherlands)

Visser, H.G.; Lopes dos Santos, Bruno F.; Verhagen, C.M.A.

2016-01-01

This paper describes the development of an optimization-based cooperative planning system for the efficient routing and scheduling of flight formations. This study considers the use of formation flight as a means to reduce the overall fuel consumption of civil aviation in long-haul operations. It

Combinations of partners’ joint venture formation motives

NARCIS (Netherlands)

Klijn, E.; Reuer, J.J.; Buckley, P.J.; Glaister, K.W.

2011-01-01

Purpose – Prior research on joint venture (JV) formation often examines a single focal firm and assumes it has a single motive for collaboration. This study seeks to investigate how formation motives of partner firms are symmetrically coupled. It considers motives in the context of different

Enhancing the Lecture: Revitalizing the Traditional Format.

Science.gov (United States)

Bonwell, Charles C.

1996-01-01

The traditional lecture format of college courses can be enhanced by including active learning designed to further course goals of learning knowledge, developing skills, or fostering attitudes. Techniques suggested include using pauses, short writing periods, think-pair-share activities, formative quizzes, lecture summaries, and several assessment…

Formation of a compact toroid for enhanced efficiency

Energy Technology Data Exchange (ETDEWEB)

Mozgovoy, A. G. [P.N. Lebedev Physical Institute, Moscow 119991 (Russian Federation); Romadanov, I. V.; Ryzhkov, S. V., E-mail: ryzhkov@power.bmstu.ru [Bauman Moscow State Technical University, Moscow 105005 (Russian Federation)

2014-02-15

We report here our results on the formation of a plasma configuration with the generic name of compact toroid (CT). A method of compact toroid formation to confine, heat and compress a plasma is investigated. Formation of a compact torus using an additional toroidal magnetic field helps to increase the plasma current to a maintainable level of the original magnetic field. We design the Compact Toroid Challenge (CTC) experiment in order to improve the magnetic flux trapping during field reversal in the formation of a compact toroid. The level of the magnetic field immersed in the plasma about 70% of the primary field is achieved. The CTC device and scheme of high level capturing of magnetic flux are presented.

Timing of College Enrollment and Family Formation Decisions

DEFF Research Database (Denmark)

Humlum, Maria; Kristoffersen, Jannie H. G.; Vejlin, Rune Majlund

The level of progression of an individual’s educational or labor market career is a potentially important factor for family formation decisions. We address this issue by considering the effects of a particular college admission system on family formation. We show that the admission system affects...... system to estimate the effect of being above the admission requirement in the year of application on later family formation decisions. We find that the admission system has substantial effects on the timing of family formation and, specifically, that the timing of college enrollment is an important...... determinant hereof. This suggests that career interruptions such as delays in the educational system can have large effects on family decision - making....

Report formatting in laboratory medicine - a call for harmony.

Science.gov (United States)

Jones, Graham R D; Legg, Michael

2018-04-19

The results of medical laboratory testing are only useful if they lead to appropriate actions by medical practitioners and/or patients. An underappreciated component of the medical testing process is the transfer of the information from the laboratory report into the reader's brain. The format of laboratory reports can be determined by the testing laboratory, which may issue a formatted report, or by electronic systems receiving information from laboratories and controlling the report format. As doctors can receive information from many laboratories, interpreting information from reports in a safe and rapid manner is facilitated by having similar report layouts and formats. Using Australia as an example, there is a wide variation in report formats in spite of a body of work to define standards for reporting. In addition to standardising of report formats, consideration needs to be given to optimisation of report formatting to facilitate rapid and unambiguous reading of the report and also interpretation of the data. Innovative report formats have been developed by some laboratories; however, wide adoption has not followed. The need to balance uniformity of reporting with appropriate innovation is a challenge for safe reporting of laboratory results. This paper discusses the current status and opportunity for improvement in safety and efficiency of the reading of laboratory reports, using current practise and developments in Australia as examples.

Bearing-Only Formation Control for Cascade Multirobots

Directory of Open Access Journals (Sweden)

Qing Han

2016-01-01

Full Text Available A new formation control method is proposed, which is used to queue multirobots in a single-direction cascade structure. In the cascade formation, each robot is a follower for the previous robot and a leader for the next robot, and the robots in the middle act as both leader and follower. The follower robot can only observe the bearing information of the leader robot. The observability of the cascade leader-follower formation is studied, which shows that the bearing-only observation meets the observability conditions required for the nonlinear system. Based on the bearing-only observations, the unscented Kalman filter (UKF is employed for the state estimation of the leader and the follower robots at all levels, which enables the real-time movement control of the follower robots via the input-output feedback control. Simulation results demonstrate that the proposed approach can efficiently control the formation of multirobots as desired.

Rethinking pattern formation in reaction-diffusion systems

Science.gov (United States)

Halatek, J.; Frey, E.

2018-05-01

The present theoretical framework for the analysis of pattern formation in complex systems is mostly limited to the vicinity of fixed (global) equilibria. Here we present a new theoretical approach to characterize dynamical states arbitrarily far from (global) equilibrium. We show that reaction-diffusion systems that are driven by locally mass-conserving interactions can be understood in terms of local equilibria of diffusively coupled compartments. Diffusive coupling generically induces lateral redistribution of the globally conserved quantities, and the variable local amounts of these quantities determine the local equilibria in each compartment. We find that, even far from global equilibrium, the system is well characterized by its moving local equilibria. We apply this framework to in vitro Min protein pattern formation, a paradigmatic model for biological pattern formation. Within our framework we can predict and explain transitions between chemical turbulence and order arbitrarily far from global equilibrium. Our results reveal conceptually new principles of self-organized pattern formation that may well govern diverse dynamical systems.

Pebble pile-up and planetesimal formation at the snow line

Science.gov (United States)

Drazkowska, J.

2017-09-01

The planetesimal formation stage represents a major gap in our understanding of planet formation process. Because of this, the late-stage planet accretion models typically make arbitrary assumptions about planetesimals and pebbles distribution, while the state-of-the-art dust evolution models predict no or little planetesimal formation. With this contribution, I present a step toward bridging the gap between the early and late stages of planet formation by models that connect dust coagulation and planetesimal formation. With the aid of evaporation, outward diffusion, and re-condensation of water vapor, pile-up of large pebbles is formed outside of the snow line that facilitates planetesimal formation by streaming instability.

Method and apparatus for nuclear heating of oil-bearing formations

International Nuclear Information System (INIS)

Alspaw, D.I.

1979-01-01

A method and apparatus are provided for using heat generated by absorption of radiation from nuclear waste materials to reduce the viscosity of petroleum products contained within a subsurface earth formation. The nuclear waste material is positioned in a salt water formation underlying the subsurface earth formation so that the radiation emitted by the material heats the salt water formation. conduction and convection transfer the heat to the subsurface earth formation, raising the temperature and thereby reducing the viscosity of the petroleum products. To prevent radioactive contamination within the salt water formation, the nuclear waste material may be encapsulated in a material selected to absorb alpha and beta radiation

Experimental Investigation of Effect on Hydrate Formation in Spray Reactor

Directory of Open Access Journals (Sweden)

Jianzhong Zhao

2015-01-01

Full Text Available The effects of reaction condition on hydrate formation were conducted in spray reactor. The temperature, pressure, and gas volume of reaction on hydrate formation were measured in pure water and SDS solutions at different temperature and pressure with a high-pressure experimental rig for hydrate formation. The experimental data and result reveal that additives could improve the hydrate formation rate and gas storage capacity. Temperature and pressure can restrict the hydrate formation. Lower temperature and higher pressure can promote hydrate formation, but they can increase production cost. So these factors should be considered synthetically. The investigation will promote the advance of gas storage technology in hydrates.

Jet formation in shock-heavy gas bubble interaction

Institute of Scientific and Technical Information of China (English)

Zhi-Gang Zhai; Ting Si; Li-Yong Zou; Xi-Sheng Luo

2013-01-01

The influences of the acoustic impedance and shock strength on the jet formation in shock-heavy gas bubble interaction are numerically studied in this work.The process of a shock interacting with a krypton or a SF6 bubble is studied by the numerical method VAS2D.As a validation,the experiments of a SF6 bubble accelerated by a planar shock were performed.The results indicate that,due to the mismatch of acoustic impedance,the way of jet formation in heavy gas bubble with different species is diversified under the same initial condition.With respect to the same bubble,the manner of jet formation is also distinctly different under different shock strengths.The disparities of the acoustic impedance result in different effects of shock focusing in the bubble,and different behaviors of shock wave inside and outside the bubble.The analyses of the wave pattern and the pressure variation indicate that the jet formation is closely associated with the pressure perturbation.Moreover,the analysis of the vorticity deposition,and comparisons of circulation and baroclinic torque show that the baroclinic vorticity also contributes to the jet formation.It is concluded that the pressure perturbation and baroclinic vorticity deposition are the two dominant factors for the jet formation in shock-heavy gas bubble interaction.

Research on formation of microsatellite communication with genetic algorithm.

Science.gov (United States)

Wu, Guoqiang; Bai, Yuguang; Sun, Zhaowei

2013-01-01

For the formation of three microsatellites which fly in the same orbit and perform three-dimensional solid mapping for terra, this paper proposes an optimizing design method of space circular formation order based on improved generic algorithm and provides an intersatellite direct spread spectrum communication system. The calculating equation of LEO formation flying satellite intersatellite links is guided by the special requirements of formation-flying microsatellite intersatellite links, and the transmitter power is also confirmed throughout the simulation. The method of space circular formation order optimizing design based on improved generic algorithm is given, and it can keep formation order steady for a long time under various absorb impetus. The intersatellite direct spread spectrum communication system is also provided. It can be found that, when the distance is 1 km and the data rate is 1 Mbps, the input wave matches preferably with the output wave. And LDPC code can improve the communication performance. The correct capability of (512, 256) LDPC code is better than (2, 1, 7) convolution code, distinctively. The design system can satisfy the communication requirements of microsatellites. So, the presented method provides a significant theory foundation for formation-flying and intersatellite communication.

Protocol for Communication Networking for Formation Flying

Science.gov (United States)

Jennings, Esther; Okino, Clayton; Gao, Jay; Clare, Loren

2009-01-01

An application-layer protocol and a network architecture have been proposed for data communications among multiple autonomous spacecraft that are required to fly in a precise formation in order to perform scientific observations. The protocol could also be applied to other autonomous vehicles operating in formation, including robotic aircraft, robotic land vehicles, and robotic underwater vehicles. A group of spacecraft or other vehicles to which the protocol applies could be characterized as a precision-formation- flying (PFF) network, and each vehicle could be characterized as a node in the PFF network. In order to support precise formation flying, it would be necessary to establish a corresponding communication network, through which the vehicles could exchange position and orientation data and formation-control commands. The communication network must enable communication during early phases of a mission, when little positional knowledge is available. Particularly during early mission phases, the distances among vehicles may be so large that communication could be achieved only by relaying across multiple links. The large distances and need for omnidirectional coverage would limit communication links to operation at low bandwidth during these mission phases. Once the vehicles were in formation and distances were shorter, the communication network would be required to provide high-bandwidth, low-jitter service to support tight formation-control loops. The proposed protocol and architecture, intended to satisfy the aforementioned and other requirements, are based on a standard layered-reference-model concept. The proposed application protocol would be used in conjunction with conventional network, data-link, and physical-layer protocols. The proposed protocol includes the ubiquitous Institute of Electrical and Electronics Engineers (IEEE) 802.11 medium access control (MAC) protocol to be used in the datalink layer. In addition to its widespread and proven use in

HDF5-Ph-Data format - Version 0.2 Draft

OpenAIRE

Antonino Ingargiola

2014-01-01

This format has been renamed Photon-HDF5 and the latest specification can be found at http://photon-hdf5.readthedocs.org/. This document contains the specifications for the HDF5-Ph-Data format. This format allows saving single-molecule spectroscopy experiments when there is at least a stream of photon timestamps. It has been envisioned as a standard container format for a broad range of experiments involving confocal microcopy. Notable examples are confocal smFRET experiments (with or wit...

Program ECSX4 (version 78-1): conversion of experimentally measured cross-section data from the four-center-exchange (X-4) format to the Livermore ECSIL format

International Nuclear Information System (INIS)

Cullen, D.E.; Perkins, S.T.

1978-01-01

A computer code called ECSX4 converts experimentally measured cross-section data from the four-center-exchange (X-4) format to the Livermore Experimental Cross-Section Information Library (ECSIL) format. The major advantage of this program is that it converts the variable format and dimensioned data of the X-4 format to the fixed-field format and consistent set of units of the ECSIL format. This consistency greatly simplifies the subsequent use of the data for cross-section evaluations. 2 figures, 3 tables

Aspartate inhibits Staphylococcus aureus biofilm formation.

Science.gov (United States)

Yang, Hang; Wang, Mengyue; Yu, Junping; Wei, Hongping

2015-04-01

Biofilm formation renders Staphylococcus aureus highly resistant to conventional antibiotics and host defenses. Four D-amino acids (D-Leu, D-Met, D-Trp and D-Tyr) have been reported to be able to inhibit biofilm formation and disassemble established S. aureus biofilms. We report here for the first time that both D- and L-isoforms of aspartate (Asp) inhibited S. aureus biofilm formation on tissue culture plates. Similar biofilm inhibition effects were also observed against other staphylococcal strains, including S. saprophyticus, S. equorum, S. chromogenes and S. haemolyticus. It was found that Asp at high concentrations (>10 mM) inhibited the growth of planktonic N315 cells, but at subinhibitory concentrations decreased the cellular metabolic activity without influencing cell growth. The decreased cellular metabolic activity might be the reason for the production of less protein and DNA in the matrix of the biofilms formed in the presence of Asp. However, varied inhibition efficacies of Asp were observed for biofilms formed by clinical staphylococcal isolates. There might be mechanisms other than decreasing the metabolic activity, e.g. the biofilm phenotypes, affecting biofilm formation in the presence of Asp. © FEMS 2015. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

GSK-3β and Memory Formation

Directory of Open Access Journals (Sweden)

Akihiko eTakashima

2012-04-01

Full Text Available In Alzheimer’s disease (AD, tau hyperphosphorylation and neurofibrillary tangle (NFT formation are strongly associated with dementia. Memory impairment is a characteristic, early symptom of AD. Glycogen synthase kinase 3 β (GSK-3β, which is activated in response to amyloid β (Aβ formation, and the normal process of aging, hyperphosphorylates tau present in the NFTs. Furthermore, activation of GSK-3β inhibits synaptic long-term potentiation (LTP through tau. It is therefore likely, that activation of GSK-3β is responsible for the memory problems seen in both advanced age, and AD. Indeed, inhibition of GSK-3 by lithium halts the progression of symptoms in patients with mild cognitive impairment (MCI. However, long-term treatment of lithium increases the risk of dementia in old age, in bipolar patients. To understand the role of GSK-3β in brain function, we analyzed memory formation in GSK-3β heterozygote, knockout mice. Results indicate that these mice show impaired memory reconsolidation. It would seem that activation of GSK-3β is required for memory maintenance, with a higher requirement as animals age, and the volume of memory increases. This in turn causes exaggerated activation of GSK-3β, leading to memory problems, and the formation of NFTs.

Star formation: Cosmic feast

Science.gov (United States)

Scaringi, Simone

2017-03-01

Low-mass stars form through a process known as disk accretion, eating up material that orbits in a disk around them. It turns out that the same mechanism also describes the formation of more massive stars.

Silver-Palladium Surfaces Inhibit Biofilm Formation

DEFF Research Database (Denmark)

Chiang, Wen-Chi; Schroll, Casper; Hilbert, Lisbeth Rischel

2009-01-01

Undesired biofilm formation is a major concern in many areas. In the present study, we investigated biofilm-inhibiting properties of a silver-palladium surface that kills bacteria by generating microelectric fields and electrochemical redox processes. For evaluation of the biofilm inhibition...... efficacy and study of the biofilm inhibition mechanism, the silver-sensitive Escherichia coli J53 and the silver-resistant E. coli J53[pMG101] strains were used as model organisms, and batch and flow chamber setups were used as model systems. In the case of the silver-sensitive strain, the silver......-palladium surfaces killed the bacteria and prevented biofilm formation under conditions of low or high bacterial load. In the case of the silver-resistant strain, the silver-palladium surfaces killed surface-associated bacteria and prevented biofilm formation under conditions of low bacterial load, whereas under...

Deep learning for SAR image formation

Science.gov (United States)

Mason, Eric; Yonel, Bariscan; Yazici, Birsen

2017-04-01

The recent success of deep learning has lead to growing interest in applying these methods to signal processing problems. This paper explores the applications of deep learning to synthetic aperture radar (SAR) image formation. We review deep learning from a perspective relevant to SAR image formation. Our objective is to address SAR image formation in the presence of uncertainties in the SAR forward model. We present a recurrent auto-encoder network architecture based on the iterative shrinkage thresholding algorithm (ISTA) that incorporates SAR modeling. We then present an off-line training method using stochastic gradient descent and discuss the challenges and key steps of learning. Lastly, we show experimentally that our method can be used to form focused images in the presence of phase uncertainties. We demonstrate that the resulting algorithm has faster convergence and decreased reconstruction error than that of ISTA.

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

Gigaseal formation in patch clamping with applications of nanotechnology

CERN Document Server

Malboubi, Majid

2014-01-01

This book presents an investigation of gigaseal formation using micro/nanotechnology. The aims of the book are twofold. First, it explains the mechanisms of gigaseal formation using the latest discoveries. Second, it provides practical techniques for frequent formation of high resistance seals. The formation of a high-resistance electrical seal, also known as a gigaseal, between a cell membrane and a glass micropipette tip is essential in patch-clamp experiments. Even though four decades have passed since the introduction of the patch-clamping technique by Neher and Sakmann, gigaseal formation remains an obstacle in developing the high-throughput ion channel screening systems required by the pharmaceutical industry. Here the authors share their latest methods for achieving gigaseal formation and describe techniques that are highly desirable at both research and industrial levels. Nanotechnology has been found to be a powerful tool for studying and modifying glass micropipettes and in tackling the problem of g...

Shock-induced star formation in a model of the Mice

OpenAIRE

Barnes, Joshua E.

2004-01-01

Star formation plays an important role in the fate of interacting galaxies. To date, most galactic simulations including star formation have used a density-dependent star formation rule designed to approximate a Schmidt law. Here, I present a new star formation rule which is governed by the local rate of energy dissipation in shocks. The new and old rules are compared using self-consistent simulations of NGC 4676; shock-induced star formation provides a better match to the observations of thi...

Evaluation of Electronic Formats of the NASA Task Load Index

Science.gov (United States)

Trujillo, Anna C.

2011-01-01

Paper questionnaires are being replaced by electronic questionnaires. The primary objective of this research was to determine whether electronic formats of paper questionnaires change subjects ratings and, if so, how the ratings changed. Results indicated that there were no statistically significant differences in self-assessment of workload when using the electronic replica or the paper format of the NASA-TLX scale. Variations of the electronic formats were tested to enforce structure to the TLX scale. Respondents had more consistent ratings with these alternative formats of the NASA-TLX. Non-pilots, in general, had lower workload ratings than pilots. The time to input the rating was the fastest for the electronic facsimile and random title formats. Also subjects preferred the electronic formats and thought these formats were easier to use. Therefore, moving questionnaires from paper to electronic media could change respondents' answers.

Radiation induced formation of giant cells (Saccharomyces uvarum). Pt. 1

International Nuclear Information System (INIS)

Baumstark-Khan, C.; Schnitzler, L.; Rink, H.

1984-01-01

X-irradiated yeast cells (Saccharomyces uvarum) grown in liquid media stop mitosis and form giant cells. Chitin ring formation, being a prerequisite for cell separation, was studied by fluorescence microscopy using Calcofluor White, a chitin specific dye. Experiments with inhibitors of DNA synthesis (hydroxyurea) and chitin synthesis (polyoxin D) demonstrate chitin ring formation to be dependent on DNA synthesis, whereas bud formation is independent of DNA synthesis and chitin ring formation respectively. Basing on these results the formation of X-ray induced giant cells implies one DNA replication which in turn induces the formation of only one chitin ring between mother cell and giant bud. Obviously no septum can be formed. Thus cell separation does not occur, but the bud already formed, produces another bud demonstrating that bud formation itself is independent of DNA synthesis. (orig.)

Heats of formation of chlorine fluorides; Chaleurs de formation des fluorures de chlore

Energy Technology Data Exchange (ETDEWEB)

Barberi, P; Caton, J; Guillin, J; Hartmanshenn, O [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1969-07-01

The enthalpies of formation of the chlorine fluorides ClF, ClF{sub 3} and ClF{sub 5} have been determined by combustion calorimetry in hydrogen. They have the respective values, 13.9, 37.2 and 57.2 Kcals.mole. Two bomb calorimeters with differing principles (high-frequency spark bomb and double compartment bomb) have been developed for this purpose. (authors) [French] Les enthalpies de formation des fluorures de chlore ClF, ClF{sub 3} et ClF{sub 5} ont ete determinees par calorimetrie de combustion dans l'hydrogene. Elles sont respectivement de 13.9, 37.2 et 57.2 Kcal.mole. Deux bombes calorimetriques de principes differents (bombe a etincelle haute frequence et bombe a double compartiment) ont ete mises au point a cette occasion. (auteurs)

Invariant Solar Sail Formations in Elliptical Sun-Synchronous Orbits

Science.gov (United States)

Parsay, Khashayar

Current and past missions that study the Earth's geomagnetic tail require multiple spacecraft to fly in formation about a highly eccentric Keplerian reference orbit that has its apogee inside a predefined science region of interest. Because the geomagnetic tail is directed along the Sun-Earth line and therefore rotates annually, inertially fixed Keplerian orbits are only aligned with the geomagnetic tail once per year. This limitation reduces the duration of the science phase to less than a few months annually. Solar sails are capable of creating non-Keplerian, Sun-synchronous orbits that rotate with the geomagnetic tail. A solar sail flying in a Sun-synchronous orbit will have a continuous presence in the geomagnetic tail throughout the entire year, which significantly improves the in situ observations of the magnetosphere. To achieve a Sun-synchronous orbit, a solar sail is required to maintain a Sun-pointing attitude, which leads to the artificial precession of the orbit apse line in a Sun-synchronous manner, leaving the orbit apogee inside the science region of interest throughout entire the year. To study the spatial and temporal variations of plasma in the highly dynamic environment of the magnetosphere, multiple spacecraft must fly in a formation. The objective for this dissertation is to investigate the feasibility of solar sail formation flying in the Earth-centered, Sun-synchronous orbit regime. The focus of this effort is to enable formation flying for a group of solar sails that maintain a nominally fixed Sun-pointing attitude during formation flight, solely for the purpose of precessing their orbit apse lines Sun-synchronously. A fixed-attitude solar sail formation is motivated by the difficulties in the simultaneous control of orbit and attitude in flying solar sails. First, the secular rates of the orbital elements resulting from the effects of solar radiation pressure (SRP) are determined using averaging theory for a Sun-pointing attitude sail

Paleogeographic Evolution of the Late Neoproterozoic and Early Phanerozoic with New Paleomagnetic Constraints from West African Craton

Science.gov (United States)

Robert, B.; Besse, J.; Blein, O.; Greff-Lefftz, M.; Baudin, T.; Fernando, L.; Meslouh, S.; Belbadaoui, M.

2015-12-01

The paleogeographic evolution of the late Neoproterozoic and early Phanerozoic is dominated by the dispersion of Rodinia and the assembly of Gondwana. The timing of these two episodes is still highly debated, partly due to the low number of good quality paleomagnetic data. In order to better constrain the paleogeography for this epoch, we bring new paleomagnetic data on volcanic series from the West African Craton (WAC), which is a key block to understand the evolution of these two supercontinents. We have sampled well dated pyroclastic and lava flows from the groups of Ouarzazate (upper Ediacaran) and Taroudant (lower Cambrian) in the Anti-Atlas (Morocco). 500 samples from 105 sites were thermally demagnetized in laboratory. Our results highlight two major groups of directions, mainly carried by minerals of the titano-hematite family. Magnetite may also contribute sometimes to the magnetization. The first group displays a single polarity direction, with a shallow inclination and a south-east declination. This direction close to the expected direction derived from the Permo-Carboniferous segment of the Gondwana apparent polar wander path (APWP) is due to a remagnetization acquired during the Kiaman reversed polarity superchron (320-262Ma). The second group, observed in the Ouarzazate and Taroudant groups, consists of a dual polarity high inclination direction and may represent the characteristic magnetization. On the basis of geologic and paleomagnetic data from literature, we constructed an APWP for both WAC and Amazonia between 615 and 530Ma, assuming these two blocks were already accreted. We found a paleomagnetic solution in which Laurentia and WAC-Amazonia remained attached from ~615Ma up to the late Ediacaran, Laurentia remaining at low latitude during this period. Around ~550Ma, WAC-Amazonia separated from Laurentia and finally collided with the other Gondwanan blocks during the lower Cambrian, marking the final accretion of Gondwana.

Cambrian Evolutionary Radiation: Context, correlation, and chronostratigraphy—Overcoming deficiencies of the first appearance datum (FAD) concept

Science.gov (United States)

Landing, Ed; Geyer, Gerd; Brasier, Martin D.; Bowring, Samuel A.

2013-08-01

Use of the first appearance datum (FAD) of a fossil to define a global chronostratigraphic unit's base can lead to intractable correlation and stability problems. FADs are diachronous—they reflect species' evolutionary history, dispersal, biofacies, preservation, collection, and taxonomy. The Cambrian Evolutionary Radiation is characterised by diachronous FADs, biofacies controls, and provincialism of taxa and ecological communities that confound a stable Lower Cambrian chronostratigraphy. Cambrian series and stage definitions require greater attention to assemblage zone successions and non-biostratigraphic, particularly carbon isotope, correlation techniques such as those that define the Ediacaran System base. A redefined, basal Cambrian Trichophycus pedum Assemblage Zone lies above the highest Ediacaran-type biotas (vendobionts, putative metazoans, and calcareous problematica such as Cloudina) and the basal Asteridium tornatum-Comasphaeridium velvetum Zone (acritarchs). This definition and the likely close correspondence of evolutionary origin and local FAD of T. pedum preserves the Fortune Head, Newfoundland, GSSP of the Cambrian base and allows the presence of sub-Cambrian, branched ichnofossils. The sub-Tommotian-equivalent base of Stage 2 (a suggested "Laolinian Stage") should be defined by the I'/L4/ZHUCE δ13C positive peak, bracketed by the lower ranges of Watsonella crosbyi and Aldanella attleborensis (molluscs) and the Skiagia ornata-Fimbrioglomerella membranacea Zone (acritarchs). The W. crosbyi and A. attleborensis FADs cannot define a Stage 2 base as they are diachronous even in the Newfoundland "type" W. crosbyi Zone. The Series 2 base cannot be based on a species' FAD owing to the provincialism of skeletalised metazoans in the Terreneuvian-Series 2 boundary interval and global heterochrony of the oldest trilobites. A Series 2 and Stage 3 (a suggested "Lenaldanian Series" and "Zhurinskyan Stage," new) GSSP base is proposed at the Siberian lower

The crazy hollow formation (Eocene) of central Utah

Science.gov (United States)

Weiss, M.P.; Warner, K.N.

2001-01-01

The Late Eocene Crazy Hollow Formation is a fluviatile and lacustrine unit that was deposited locally in the southwest arm of Lake Uinta during and after the last stages of the lake the deposited the Green River Formation. Most exposures of the Crazy Hollow are located in Sanpete and Sevier Counties. The unit is characterized by a large variety of rock types, rapid facies changes within fairly short distances, and different lithofacies in the several areas where outcrops of the remnants of the formation are concentrated. Mudstone is dominant, volumetrically, but siltstone, shale, sandstone, conglomerate and several varieties of limestone are also present. The fine-grained rocks are mostly highly colored, especially in shades of yellow, orange and red. Sand grains, pebbles and small cobbles of well-rounded black chert are widespread, and "salt-and-pepper sandstone" is the conspicuous characteristic of the Crazy Hollow. The salt-and-pepper sandstone consists of grains of black chert, white chert, quartz and minor feldspar. The limestone beds and lenses are paludal and lacustrine in origin; some are fossiliferous, and contain the same fauna found in the Green River Formation. With trivial exceptions, the Crazy Hollow Formation lies on the upper, limestone member of the Green River Formation, and the beds of the two units are always accordant in attitude. The nature of the contact differs locally: at some sites there is gradation from the Green River to the Crazy Hollow; at others, rocks typical of the two units intertongue; elsewhere there is a disconformity between the two. A variety of bedrock units overlie the Crazy Hollow at different sites. In the southeasternmost districts it is overlain by the late Eocene formation of Aurora; in western Sevier County it is overlain by the Miocene-Pliocene Sevier River Formation; in northernmost Sanpete County it is overlain by the Oligocene volcanics of the Moroni Formation. At many sites bordering Sanpete and Sevier Valleys

12 CFR 749.4 - Format for vital records preservation.

Science.gov (United States)

2010-01-01

... 12 Banks and Banking 6 2010-01-01 2010-01-01 false Format for vital records preservation. 749.4... RECORDS PRESERVATION PROGRAM AND APPENDICES-RECORD RETENTION GUIDELINES; CATASTROPHIC ACT PREPAREDNESS GUIDELINES § 749.4 Format for vital records preservation. Preserved records may be in any format that can be...

Tacuarembo formation: its age and a new nomenclatural proposal

International Nuclear Information System (INIS)

Soto, M.; Perea, D.; Martinez, S.; Veroslavsky, G.

2004-01-01

Tacuarembo Formation: its age and a new nomenclatural proposal. A new nomenclatural proposal concerning the Tacuarembo Formation is formalized, denominating the Lower and Upper members as Martinote Member (stratotype: Cerro Batovi) and Rivera Member (stratotype: Subida de Pena, respectively. The Assemblage-Zone of Priohybodus arambourgi-Asiatoceratodus tiguidensis is defined. Fossil conchostracans and fishes from Martinote Member indicate a Kimmeridgian-Albian age for this unit, which in addition to the stratigraphic relationships with Arapey Formation implies that Tacuarembo Formation was deposited in the Kimmeridgian-Hautevirian interval [es

On the mechanism of muonium formation in liquid water

International Nuclear Information System (INIS)

Byakov, V.M.; Firsov, V.G.

1986-01-01

The experimental data on the influence of some solutes in water on formation probabilities of muonium, positronium and radiolytic hydrogen are compared. It is shown that the inhibiting action is very similar in all cases. This means that the formation mechanisms of muonium, positronium and radiolytic hydrogen have common features. Taking into account that the formation of radiolytic hydrogen and that of positronium proceeds via recombination mechanism with unsolvated electron as one of the precursors, it is asserted that the muonium formation mechanism is similar. (author)

Formation of nuclear security culture in Ukraine

Directory of Open Access Journals (Sweden)

V. I. Gavryliuk

2014-06-01

Full Text Available Issues of nuclear security culture formation are considered in the article. Information on establishing and ac-tivity of Working Group for formation and development of nuclear security culture being held during 2010 – 2013 is given. An issue of regulation of activity on formation and development of nuclear security culture is il-lustrated. Analysis of the survey results regarding efficiency assessment of the work aimed to form and develop of nuclear security culture of nuclear facilities is carried out. The results show that the nuclear security culture of the most of nuclear facilities in Ukraine has been formed and is at the stage of development.

Star formation is boosted (and quenched) from the inside-out: radial star formation profiles from MaNGA

Science.gov (United States)

Ellison, Sara L.; Sánchez, Sebastian F.; Ibarra-Medel, Hector; Antonio, Braulio; Mendel, J. Trevor; Barrera-Ballesteros, Jorge

2018-02-01

The tight correlation between total galaxy stellar mass and star formation rate (SFR) has become known as the star-forming main sequence. Using ˜487 000 spaxels from galaxies observed as part of the Sloan Digital Sky Survey Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey, we confirm previous results that a correlation also exists between the surface densities of star formation (ΣSFR) and stellar mass (Σ⋆) on kpc scales, representing a `resolved' main sequence. Using a new metric (ΔΣSFR), which measures the relative enhancement or deficit of star formation on a spaxel-by-spaxel basis relative to the resolved main sequence, we investigate the SFR profiles of 864 galaxies as a function of their position relative to the global star-forming main sequence (ΔSFR). For galaxies above the global main sequence (positive ΔSFR) ΔΣSFR is elevated throughout the galaxy, but the greatest enhancement in star formation occurs at small radii (<3 kpc, or 0.5Re). Moreover, galaxies that are at least a factor of 3 above the main sequence show diluted gas phase metallicities out to 2Re, indicative of metal-poor gas inflows accompanying the starbursts. For quiescent/passive galaxies that lie at least a factor of 10 below the star-forming main sequence, there is an analogous deficit of star formation throughout the galaxy with the lowest values of ΔΣSFR in the central 3 kpc. Our results are in qualitative agreement with the `compaction' scenario in which a central starburst leads to mass growth in the bulge and may ultimately precede galactic quenching from the inside-out.

Petrography, Geochemistry and Proposed Genesis of Ordovician Oolitic Iron Formation Members of the Lashkarak Formation, Eastern Alborz

International Nuclear Information System (INIS)

Maghsoudloo Mahalli, M.; Shafiei Bafti, B.

2016-01-01

Mineralogical characteristics combined with geochemical data show that anomalous values of Fe in studied carbonate argillite formations with respect to common sedimentary rocks are related to the abundance of iron-bearing oolites as oxides such as hematite and goethite, and the clay mineral chamosite. Based on Fe, Mg and Ca concentrations, oolitic iron formations can be divided into low-grade and high-grade iron formations. The former is characterized by chamosite and calcite, whereas the latter consists ofhematite and calcite. This research, along with available paleo-geographic and sedimentological information suggests that the iron for the formation of iron oolites was available from normal sea water and Fe could be carried as clastic particles along with clays or coating of clay particles derived from weathering and erosion of shales from adjacent land. High contents of K and Si in oolitic iron horizons, the presence of detrital zircon, quartz and clay minerals within oolites and also in the matrix of these rocks confirm the proposed model and show the important role of Fe-bearing clay minerals in the genesis of the primary chamositic oolites in an environment with p H=5-9 and medium-weak redox conditions (Maynard, 1983; Maynard, 1986). The abundance of hematite relative to goethite in the Fe-oolites, dense and elliptical oolites as well as the frequent occurrence of calcite veinlets cutting oolite beds has been attributed to diagenetic processes and the modification of chamosite and goethite to hematite. Our findings indicate that the studied members can be classified as low-grade oolitic iron formation (average 21 wt.% Fe) which do not have economic importance at present.

Investigation of Primary Recovery in Low-Permeability Oil Formations: A Look at the Cardium Formation, Alberta (Canada

Directory of Open Access Journals (Sweden)

Ghaderi S.M.

2014-12-01

Full Text Available Tight oil formations (permeability < 1 mD in Western Canada have recently emerged as a reliable resource of light oil supply owing to the use of multifractured horizontal wells. The Cardium formation, which contains 25% of Alberta’s total discovered light oil (according to Alberta Energy Resources Conservation Board, consists of conventional and unconventional (low-permeability or tight play areas. The conventional play areas have been developed since 1957. Contrarily, the development of unconventional play is a recent event, due to considerably poorer reservoir properties which increases the risk associated with capital investment. This in turn implies the need for a comprehensive and critical study of the area before planning any development strategy. This paper presents performance results from the low permeability portions of the Cardium formation where new horizontal wells have been drilled and stimulated in multiple stages to promote transverse hydraulic fractures. Development of the tight Cardium formation using primary recovery is considered. The production data of these wells was first matched using a black oil simulator. The calibrated model presented was used for performance perditions based on sensitivity studies and investigations that encompassed design factors such as well spacing, fracture properties and operational constraints.

Standard free energy of formation of iron iodide

Science.gov (United States)

Khandkar, A.; Tare, V. B.; Wagner, J. B., Jr.

1983-01-01

An experiment is reported where silver iodide is used to determine the standard free energy of formation of iron iodide. By using silver iodide as a solid electrolyte, a galvanic cell, Ag/AgI/Fe-FeI2, is formulated. The standard free energy of formation of AgI is known, and hence it is possible to estimate the standard free energy of formation of FeI2 by measuring the open-circuit emf of the above cell as a function of temperature. The free standard energy of formation of FeI2 determined by this method is -38784 + 24.165T cal/mol. It is estimated that the maximum error associated with this method is plus or minus 2500 cal/mol.

Terrestrial planet formation in a protoplanetary disk with a local mass depletion: A successful scenario for the formation of Mars

Energy Technology Data Exchange (ETDEWEB)

Izidoro, A.; Winter, O. C. [UNESP, Univ. Estadual Paulista - Grupo de Dinâmica Orbital and Planetologia, Guaratinguetá, CEP 12.516-410, São Paulo (Brazil); Haghighipour, N. [Institute for Astronomy and NASA Astrobiology Institute, University of Hawaii-Manoa, Honolulu, HI 96822 (United States); Tsuchida, M., E-mail: izidoro@feg.unesp.br, E-mail: nader@ifa.hawaii.edu [UNESP, Univ. Estadual Paulista, DCCE-IBILCE, São José do Rio Preto, CEP 15.054-000, São Paulo (Brazil)

2014-02-10

Models of terrestrial planet formation for our solar system have been successful in producing planets with masses and orbits similar to those of Venus and Earth. However, these models have generally failed to produce Mars-sized objects around 1.5 AU. The body that is usually formed around Mars' semimajor axis is, in general, much more massive than Mars. Only when Jupiter and Saturn are assumed to have initially very eccentric orbits (e ∼ 0.1), which seems fairly unlikely for the solar system, or alternately, if the protoplanetary disk is truncated at 1.0 AU, simulations have been able to produce Mars-like bodies in the correct location. In this paper, we examine an alternative scenario for the formation of Mars in which a local depletion in the density of the protosolar nebula results in a non-uniform formation of planetary embryos and ultimately the formation of Mars-sized planets around 1.5 AU. We have carried out extensive numerical simulations of the formation of terrestrial planets in such a disk for different scales of the local density depletion, and for different orbital configurations of the giant planets. Our simulations point to the possibility of the formation of Mars-sized bodies around 1.5 AU, specifically when the scale of the disk local mass-depletion is moderately high (50%-75%) and Jupiter and Saturn are initially in their current orbits. In these systems, Mars-analogs are formed from the protoplanetary materials that originate in the regions of disk interior or exterior to the local mass-depletion. Results also indicate that Earth-sized planets can form around 1 AU with a substantial amount of water accreted via primitive water-rich planetesimals and planetary embryos. We present the results of our study and discuss their implications for the formation of terrestrial planets in our solar system.

Dark-ages Reionization and Galaxy Formation Simulation - XIV. Gas accretion, cooling, and star formation in dwarf galaxies at high redshift

Science.gov (United States)

Qin, Yuxiang; Duffy, Alan R.; Mutch, Simon J.; Poole, Gregory B.; Geil, Paul M.; Mesinger, Andrei; Wyithe, J. Stuart B.

2018-06-01

We study dwarf galaxy formation at high redshift (z ≥ 5) using a suite of high-resolution, cosmological hydrodynamic simulations and a semi-analytic model (SAM). We focus on gas accretion, cooling, and star formation in this work by isolating the relevant process from reionization and supernova feedback, which will be further discussed in a companion paper. We apply the SAM to halo merger trees constructed from a collisionless N-body simulation sharing identical initial conditions to the hydrodynamic suite, and calibrate the free parameters against the stellar mass function predicted by the hydrodynamic simulations at z = 5. By making comparisons of the star formation history and gas components calculated by the two modelling techniques, we find that semi-analytic prescriptions that are commonly adopted in the literature of low-redshift galaxy formation do not accurately represent dwarf galaxy properties in the hydrodynamic simulation at earlier times. We propose three modifications to SAMs that will provide more accurate high-redshift simulations. These include (1) the halo mass and baryon fraction which are overestimated by collisionless N-body simulations; (2) the star formation efficiency which follows a different cosmic evolutionary path from the hydrodynamic simulation; and (3) the cooling rate which is not well defined for dwarf galaxies at high redshift. Accurate semi-analytic modelling of dwarf galaxy formation informed by detailed hydrodynamical modelling will facilitate reliable semi-analytic predictions over the large volumes needed for the study of reionization.

Dark-ages Reionization and Galaxy Formation Simulation - XIV. Gas accretion, cooling and star formation in dwarf galaxies at high redshift

Science.gov (United States)

Qin, Yuxiang; Duffy, Alan R.; Mutch, Simon J.; Poole, Gregory B.; Geil, Paul M.; Mesinger, Andrei; Wyithe, J. Stuart B.

2018-03-01

We study dwarf galaxy formation at high redshift (z ≥ 5) using a suite of high-resolution, cosmological hydrodynamic simulations and a semi-analytic model (SAM). We focus on gas accretion, cooling and star formation in this work by isolating the relevant process from reionization and supernova feedback, which will be further discussed in a companion paper. We apply the SAM to halo merger trees constructed from a collisionless N-body simulation sharing identical initial conditions to the hydrodynamic suite, and calibrate the free parameters against the stellar mass function predicted by the hydrodynamic simulations at z = 5. By making comparisons of the star formation history and gas components calculated by the two modelling techniques, we find that semi-analytic prescriptions that are commonly adopted in the literature of low-redshift galaxy formation do not accurately represent dwarf galaxy properties in the hydrodynamic simulation at earlier times. We propose 3 modifications to SAMs that will provide more accurate high-redshift simulations. These include 1) the halo mass and baryon fraction which are overestimated by collisionless N-body simulations; 2) the star formation efficiency which follows a different cosmic evolutionary path from the hydrodynamic simulation; and 3) the cooling rate which is not well defined for dwarf galaxies at high redshift. Accurate semi-analytic modelling of dwarf galaxy formation informed by detailed hydrodynamical modelling will facilitate reliable semi-analytic predictions over the large volumes needed for the study of reionization.

DELLA proteins regulate arbuscule formation in arbuscular mycorrhizal symbiosis.

Science.gov (United States)

Floss, Daniela S; Levy, Julien G; Lévesque-Tremblay, Véronique; Pumplin, Nathan; Harrison, Maria J

2013-12-17

Most flowering plants are able to form endosymbioses with arbuscular mycorrhizal fungi. In this mutualistic association, the fungus colonizes the root cortex and establishes elaborately branched hyphae, called arbuscules, within the cortical cells. Arbuscule development requires the cellular reorganization of both symbionts, and the resulting symbiotic interface functions in nutrient exchange. A plant symbiosis signaling pathway controls the development of the symbiosis. Several components of the pathway have been identified, but transcriptional regulators that control downstream pathways for arbuscule formation are still unknown. Here we show that DELLA proteins, which are repressors of gibberellic acid (GA) signaling and function at the nexus of several signaling pathways, are required for arbuscule formation. Arbuscule formation is severely impaired in a Medicago truncatula Mtdella1/Mtdella2 double mutant; GA treatment of wild-type roots phenocopies the della double mutant, and a dominant DELLA protein (della1-Δ18) enables arbuscule formation in the presence of GA. Ectopic expression of della1-Δ18 suggests that DELLA activity in the vascular tissue and endodermis is sufficient to enable arbuscule formation in the inner cortical cells. In addition, expression of della1-Δ18 restores arbuscule formation in the symbiosis signaling pathway mutant cyclops/ipd3, indicating an intersection between DELLA and symbiosis signaling for arbuscule formation. GA signaling also influences arbuscule formation in monocots, and a Green Revolution wheat variety carrying dominant DELLA alleles shows enhanced colonization but a limited growth response to arbuscular mycorrhizal symbiosis.

Microbial Formation of Ethane in Anoxic Estuarine Sediments

OpenAIRE

Oremland, Ronald S.

1981-01-01

Estuarine sediment slurries produced methane and traces of ethane when incubated under hydrogen. Formation of methane occurred over a broad temperature range with an optimum above 65°C. Ethane formation had a temperature optimum at 40°C. Formation of these two gases was inhibited by air, autoclaving, incubation at 4 and 80°C, and by the methanogenic inhibitor, 2-bromoethanesulfonic acid. Ethane production was stimulated by addition of ethylthioethanesulfonic acid, and production from ethylthi...

The format of things

DEFF Research Database (Denmark)

Jørnø, Rasmus Leth

this conception is identified as “the Format of Things.” The format is embedded in our everyday thinking. In relation to design,it is found in the name taken by the design community, that is human-computer interaction (HCI), and it is mirrored in the desktop metaphor, wherein information is conceived...... available. It consists of philosophical considerations on matters of relevance for the design of interfaces. It takes the position that the graphical user interfaces of computers (the Desktop Metaphor or Windows, Icons, Menus, Pointers [‘WIMP’]) that ordinarily come to mind for most people are cognates......The development of novel interfaces is one of the most important current design challenges for the intellectual, cultural and cognitive evolution of human imagination and knowledge work. Unfortunately, the thinking surrounding this design challenge is heavily mired in conceptions that harbor...

THE BLACK HOLE FORMATION PROBABILITY

Energy Technology Data Exchange (ETDEWEB)

Clausen, Drew; Piro, Anthony L.; Ott, Christian D., E-mail: dclausen@tapir.caltech.edu [TAPIR, Walter Burke Institute for Theoretical Physics, California Institute of Technology, Mailcode 350-17, Pasadena, CA 91125 (United States)

2015-02-01

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 {sub BH}(M {sub ZAMS}). Although we find that it is difficult to derive a unique P {sub BH}(M {sub ZAMS}) using current measurements of both the BH mass distribution and the degree of chemical enrichment by massive stars, we demonstrate how P {sub BH}(M {sub 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 {sub BH}(M {sub 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.

Comparison of Brief Summary Formats Through a Health Literacy Lens.

Science.gov (United States)

Sharp, Michele L; Hall, Lori; Eleftherion, Anthony; Simpson, Katherine; Neuhauser, Linda

2018-01-01

Print pharmaceutical advertisements in the United States require inclusion of a brief summary of side effects, warnings, precautions, and contraindications from the labeling. The full package insert, which sponsors have traditionally used to fulfill the brief summary requirement, does not adhere to health literacy best practices, limiting its value to consumers. This study compared the understandability and usability of brief summaries in 3 formats designed to be more consumer friendly. Three brief summary formats were tested: (1) 2-column "Question and Answer"; (2) "Prescription Drug Facts Box," similar to current US over-the-counter drug facts labeling; and (3) "Health Literacy," based on clear communication principles. Researchers evaluated the formats using the Suitability Assessment of Materials (SAM) tool and conducted structured, scripted, one-on-one interviews (usability tests) with participants with estimated low to average education levels. This research was replicated across 2 therapeutic areas (type 2 diabetes and plaque psoriasis). SAM scores showed that the Health Literacy format outperformed the Question and Answer format and the Prescription Drug Facts Box format in both therapeutic areas, with both Health Literacy brief summaries rated on the SAM as "superior." Qualitative usability tests supported the SAM findings, with the Health Literacy format preferred consistently over the Question and Answer format, and more often than not over the Prescription Drug Facts Box format. Sponsors can employ a user-tested Health Literacy format to improve the understandability and usability of brief summaries with patients.

Program PLOTC4. (Version 87-1). Plot evaluated data from the ENDF/B format and/or experimental data which is in a computation format

International Nuclear Information System (INIS)

Cullen, D.E.

1987-06-01

Experimental and evaluated nuclear reaction data are world-wide compiled in EXFOR format (see document IAEA-NDS-1) and ENDF format (see document IAEA-NDS-10), respectively. The computer program PLOTC4 described in the present document plots data from both formats; EXFOR data must be converted first to a ''computation format'' (see document IAEA-NDS-80). The program is available upon request costfree from the IAEA Nuclear Data Section. (author)

Bainite formation kinetics in high carbon alloyed steel

International Nuclear Information System (INIS)

Luzginova, N.V.; Zhao, L.; Sietsma, J.

2008-01-01

In recent years, many investigations have been carried out on the modeling of the bainite formation. In the present work, a physical approach proposed in the literature is implemented to model the formation of lower bainite in high carbon steels (1 wt.% C). In this model, the carbon diffusion is assumed to control the kinetics of the bainite formation. Both the nucleation and the growth rates are considered in an Avrami type analysis. The effect of alloying elements is taken into account considering only the thermodynamics of the system. The results and the physical meaning of the model parameters are discussed. It is shown that the diffusional approach gives a reasonable description of bainite formation kinetics in high carbon steel. Only two fitting parameters are used: the first accounts for carbon grain-boundary diffusion and the second is the initial nucleation-site density. The model satisfactorily accounts for the effect of transformation temperature, but does not take into account the carbide precipitation during bainite formation and the effect of alloying elements on the diffusion coefficient of carbon

Mechanisms of Formation of Human Culture in Education

Directory of Open Access Journals (Sweden)

Baboshina Helen B.

2017-12-01

Full Text Available The relevance of the research problem lies in the necessity of an axiological approach to the formation of the personality in education and the task of strengthening the ideal image of the function. The aim of this article is studying and understanding the culture of personality formation mechanisms in relation to future specialists. The leading method of research was the theoretical analysis of philosophical and cultural approaches to the cultural formation of the personality and to the content of human culture. Content analysis was based on the philosophical and cultural concepts of V. S. Bibler, M. Buber, J. G. Herder, I. Kant, L. N. Kogan, D. S. Likhachev, A. Schweitzer, M. Scheler, and others. The experiment method was the experimental realization of formation stages of the future specialist as a person of culture, which allowed revealing the positive role of cultural mechanisms in this process. The result is the stages of human culture formation as well as mechanisms for their implementation. The article may be useful for specialists of the educational sphere, social philosophers, and culturologists.

Formation control of surface marine craft using Lagrange multipliers

DEFF Research Database (Denmark)

Ihle, Ivar-Andre F.; Jouffroy, Jerome; Fossen, Thor I.

We propose a method for constructing control laws for formation control of marine craft using classical tools from analytical mechanics. The control law is based on applying inter-vessel constraint functions which again impose forces on the individual vessels that maintain the given constraints...... on the total system. In this way, a formation can be assembled and stay together when exposed to external forces. A brief comparison with other control designs for a group of marine craft is done. Further, control laws for formation assembling (with dynamic positioning), and formation keeping during...

The role of formative feedback in promoting higher order thinking ...

African Journals Online (AJOL)

The role of formative feedback in promoting higher order thinking skills in ... activities, task characteristics, validating students' thinking, and providing feedback. ... Keywords: classroom environment, formative assessment, formative feedback, ...

Aminobutyric acid and formation of higher alcohols by Saccharomyces carlsbergenesis

Energy Technology Data Exchange (ETDEWEB)

Babaeva, S A; Veselov, I Ya; Gracheva, I M

1966-01-01

Aminobutyric acid (1) added before the start of fermentation increased the formation of propyl-, isobutyl-, and isoamyl alcohols. With addition of I after 24, 28, or 72 hours of fermentation, the formation of the alcohols gradually decreased. Addition of I after 3 days of fermentation did not affect formation of the higher alcohols. I was not the source of formation of the higher alcohols, but affected the metabolism of carbohydrates and N in the cells. Formation of hexyl alcohols and high amounts of aldehydes was observed only during aerobic fermentation.

Apparatus and method for determining characteristics of subsurface formations

International Nuclear Information System (INIS)

Coates, G.R.

1978-01-01

A method for the determination of a composite parameter of the formation water in formations surrounding a borehole using capture cross section data (or the conductivity) of the formation water is described and its use for the accurate determination of characteristics such as water saturation even in shaly regions, is demonstrated. (UK)

Research of Self-Formation Nanostructures

Directory of Open Access Journals (Sweden)

Romas Petrauskas

2011-08-01

Full Text Available Lateral etching processes for the modeling of the geometry of self-formation nanostructures with Silvaco TCAD Athena program are analyzed. Self-formation nanostructures is modeled with different mask selectivity values equal to 2, 10, 40 and 100 with respect to the etching layer, with the etching duration of 0–180 s. The etching rates are constant – 1.33 nm/s. The analysis of the dependence of the etching systematic error on its thickness has been carried out. The computer modeled results are close to the ones produced by means of the application of the analytical calculation models by other authors.Article in Lithuanian

Radionuclide migration in geological formations

International Nuclear Information System (INIS)

Barbreau, A.; Heremans, R.; Skytte Jensen, B.

1980-01-01

Radioactive waste disposal into geological formation is based on the capacity of rocks to confine radioactivity for a long period of time. Radionuclide migration from the repository to the environment depends on different mechanisms and phenomena whose two main ones are groundwater flow and the retention and ion-exchange property of rocks. Many studies are underway presently in EEC countries concerning hydrodynamic characteristics of deep geological formations as well as in radionuclide retention capacity and modelling. Important results have already been achieved which show the complexity of some phenomena and further studies shall principally be developed taking into account real conditions of the repository and its environment

THE STAGES OF ACCOUNTING POLICIES FORMATION

OpenAIRE

Kafka, Sofiia

2017-01-01

In the article the research of the existing scientists’ approaches to the procedure of the company accounting policy formation have been done, their critical analysis has been made, the major groups of issues and problems raised in scientific works have been found out, and those ones, which require the further up-to- date refinement, have been identified: the formation of the stages in projecting of the accounting policy in accordance with requirements of legislation. For the purposes of stud...

Star formation histories of irregular galaxies

International Nuclear Information System (INIS)

Gallagher, J.S. III; Hunter, D.A.; Tutukov, A.V.

1984-01-01

We explore the star formation histories of a selection of irregular and spiral galaxies by using three parameters that sample the star formation rate (SFR) at different epochs: (1) the mass of a galaxy in the form of stars measures the SFR integrated over a galaxy's lifetime; (2) the blue luminosity is dominated primarily by stars formed over the past few billion years; and (3) Lyman continuum photon fluxes derived from Hα luminosities give the current ( 8 yr) SFR

Optimal Formation of Multirobot Systems Based on a Recurrent Neural Network.

Science.gov (United States)

Wang, Yunpeng; Cheng, Long; Hou, Zeng-Guang; Yu, Junzhi; Tan, Min

2016-02-01

The optimal formation problem of multirobot systems is solved by a recurrent neural network in this paper. The desired formation is described by the shape theory. This theory can generate a set of feasible formations that share the same relative relation among robots. An optimal formation means that finding one formation from the feasible formation set, which has the minimum distance to the initial formation of the multirobot system. Then, the formation problem is transformed into an optimization problem. In addition, the orientation, scale, and admissible range of the formation can also be considered as the constraints in the optimization problem. Furthermore, if all robots are identical, their positions in the system are exchangeable. Then, each robot does not necessarily move to one specific position in the formation. In this case, the optimal formation problem becomes a combinational optimization problem, whose optimal solution is very hard to obtain. Inspired by the penalty method, this combinational optimization problem can be approximately transformed into a convex optimization problem. Due to the involvement of the Euclidean norm in the distance, the objective function of these optimization problems are nonsmooth. To solve these nonsmooth optimization problems efficiently, a recurrent neural network approach is employed, owing to its parallel computation ability. Finally, some simulations and experiments are given to validate the effectiveness and efficiency of the proposed optimal formation approach.

Standard molar enthalpy of formation of methoxyacetophenone isomers

International Nuclear Information System (INIS)

Amaral, Luísa M.P.F.; Morais, Victor M.F.; Ribeiro da Silva, Manuel A.V.

2014-01-01

Highlights: • Experimental and computational energetic study of methoxyacetophenone isomers. • Enthalpies of formation and phase transition determined by calorimetric techniques. • Quantum chemical calculations allowed estimation of enthalpies of formation. • Structure and energy correlations were established. - Abstract: Values of the standard (p o = 0.1 MPa) molar enthalpy of formation of 2′-, 3′- and 4′-methoxyacetophenones were derived from their standard molar energy of combustion, in oxygen, at T = 298.15 K, measured by static bomb combustion calorimetry. The Calvet high temperature vacuum sublimation technique was used to measure the enthalpies of sublimation/vaporization of the compounds studied. The standard molar enthalpies of formation of the three compounds, in the gaseous phase, at T = 298.15 K, have been derived from the corresponding standard molar enthalpies of formation in the condensed phase and the standard molar enthalpies for the phase transition. The results obtained are −(232.0 ± 2.5), −(237.7 ± 2.7) and −(241.1 ± 2.1) kJ · mol −1 for 2′-, 3′- and 4′-methoxyacetophenone, respectively. Standard molar enthalpies of formation were also estimated from different methodologies: the Cox scheme as well as two different computational approaches using density functional theory-based B3LYP and the multilevel G3 methodologies

Peculiar early-type galaxies with central star formation

International Nuclear Information System (INIS)

Ge Chong; Gu Qiusheng

2012-01-01

Early-type galaxies (ETGs) are very important for understanding the formation and evolution of galaxies. Recent observations suggest that ETGs are not simply old stellar spheroids as we previously thought. Widespread recent star formation, cool gas and dust have been detected in a substantial fraction of ETGs. We make use of the radial profiles of g — r color and the concentration index from the Sloan Digital Sky Survey database to pick out 31 peculiar ETGs with central blue cores. By analyzing the photometric and spectroscopic data, we suggest that the blue cores are caused by star formation activities rather than the central weak active galactic nucleus. From the results of stellar population synthesis, we find that the stellar population of the blue cores is relatively young, spreading from several Myr to less than one Gyr. In 14 galaxies with H I observations, we find that the average gas fraction of these galaxies is about 0.55. The bluer galaxies show a higher gas fraction, and the total star formation rate (SFR) correlates very well with the H I gas mass. The star formation history of these ETGs is affected by the environment, e.g. in the denser environment the H I gas is less and the total SFR is lower. We also discuss the origin of the central star formation of these early-type galaxies.

ON THE STAR FORMATION PROPERTIES OF VOID GALAXIES

Energy Technology Data Exchange (ETDEWEB)

Moorman, Crystal M.; Moreno, Jackeline; White, Amanda; Vogeley, Michael S. [Department of Physics, Drexel University, 3141 Chestnut Street, Philadelphia, PA 19104 (United States); Hoyle, Fiona [Pontifica Universidad Catolica de Ecuador, 12 de Octubre 1076 y Roca, Quito (Ecuador); Giovanelli, Riccardo; Haynes, Martha P., E-mail: crystal.m.moorman@drexel.edu [Center for Radiophysics and Space Research, Space Sciences Building, Cornell University Ithaca, NY 14853 (United States)

2016-11-10

We measure the star formation properties of two large samples of galaxies from the SDSS in large-scale cosmic voids on timescales of 10 and 100 Myr, using H α emission line strengths and GALEX FUV fluxes, respectively. The first sample consists of 109,818 optically selected galaxies. We find that void galaxies in this sample have higher specific star formation rates (SSFRs; star formation rates per unit stellar mass) than similar stellar mass galaxies in denser regions. The second sample is a subset of the optically selected sample containing 8070 galaxies with reliable H i detections from ALFALFA. For the full H i detected sample, SSFRs do not vary systematically with large-scale environment. However, investigating only the H i detected dwarf galaxies reveals a trend toward higher SSFRs in voids. Furthermore, we estimate the star formation rate per unit H i mass (known as the star formation efficiency; SFE) of a galaxy, as a function of environment. For the overall H i detected population, we notice no environmental dependence. Limiting the sample to dwarf galaxies still does not reveal a statistically significant difference between SFEs in voids versus walls. These results suggest that void environments, on average, provide a nurturing environment for dwarf galaxy evolution allowing for higher specific star formation rates while forming stars with similar efficiencies to those in walls.

Pore Scale Dynamics of Microemulsion Formation.

Science.gov (United States)

Unsal, Evren; Broens, Marc; Armstrong, Ryan T

2016-07-19

Experiments in various porous media have shown that multiple parameters come into play when an oleic phase is displaced by an aqueous solution of surfactant. In general, the displacement efficiency is improved when the fluids become quasi-miscible. Understanding the phase behavior oil/water/surfactant systems is important because microemulsion has the ability to generate ultralow interfacial tension (microemulsion formation and the resulting properties under equilibrium conditions. However, the majority of applications where microemulsion is present also involve flow, which has received relatively less attention. It is commonly assumed that the characteristics of an oil/water/surfactant system under flowing conditions are identical to the one under equilibrium conditions. Here, we show that this is not necessarily the case. We studied the equilibrium phase behavior of a model system consisting of n-decane and an aqueous solution of olefin sulfonate surfactant, which has practical applications for enhanced oil recovery. The salt content of the aqueous solution was varied to provide a range of different microemulsion compositions and oil-water interfacial tensions. We then performed microfluidic flow experiments to study the dynamic in situ formation of microemulsion by coinjecting bulk fluids of n-decane and surfactant solution into a T-junction capillary geometry. A solvatochromatic fluorescent dye was used to obtain spatially resolved compositional information. In this way, we visualized the microemulsion formation and the flow of it along with the excess phases. A complex interaction between the flow patterns and the microemulsion properties was observed. The formation of microemulsion influenced the flow regimes, and the flow regimes affected the characteristics of the microemulsion formation. In particular, at low flow rates, slug flow was observed, which had profound consequences on the pore scale mixing behavior and resulting microemulsion properties.

Blood drop patterns: Formation and applications.

Science.gov (United States)

Chen, Ruoyang; Zhang, Liyuan; Zang, Duyang; Shen, Wei

2016-05-01

The drying of a drop of blood or plasma on a solid substrate leads to the formation of interesting and complex patterns. Inter- and intra-cellular and macromolecular interactions in the drying plasma or blood drop are responsible for the final morphologies of the dried patterns. Changes in these cellular and macromolecular components in blood caused by diseases have been suspected to cause changes in the dried drop patterns of plasma and whole blood, which could be used as simple diagnostic tools to identify the health of humans and livestock. However, complex physicochemical driving forces involved in the pattern formation are not fully understood. This review focuses on the scientific development in microscopic observations and pattern interpretation of dried plasma and whole blood samples, as well as the diagnostic applications of pattern analysis. Dried drop patterns of plasma consist of intricate visible cracks in the outer region and fine structures in the central region, which are mainly influenced by the presence and concentration of inorganic salts and proteins during drying. The shrinkage of macromolecular gel and its adhesion to the substrate surface have been thought to be responsible for the formation of the cracks. Dried drop patterns of whole blood have three characteristic zones; their formation as functions of drying time has been reported in the literature. Some research works have applied engineering treatment to the evaporation process of whole blood samples. The sensitivities of the resultant patterns to the relative humidity of the environment, the wettability of the substrates, and the size of the drop have been reported. These research works shed light on the mechanisms of spreading, evaporation, gelation, and crack formation of the blood drops on solid substrates, as well as on the potential applications of dried drop patterns of plasma and whole blood in diagnosis. Crown Copyright © 2016. Published by Elsevier B.V. All rights reserved.

Fixed geometric formation structure in formation control problem for group of robots with dynamically changing number of robots in the group

Directory of Open Access Journals (Sweden)

N. S. Morozova

2015-01-01

Full Text Available The article considers a problem of the decentralization-based approach to formation control of a group of agents, which simulate mobile autonomous robots. The agents use only local information limited by the covering range of their sensors. The agents have to build and maintain the formation, which fits to the defined target geometric formation structure with desired accuracy during the movement to the target point. At any point in time the number of agents in the group can change unexpectedly (for example, as a result of the agent failure or if a new agent joins the group.The aim of the article is to provide the base control rule, which solves the formation control problem, and to develop its modifications, which provide the correct behavior in case the agent number in the group is not equal to the size of the target geometric formation structure. The proposed base control rule, developed by the author, uses the method of involving virtual leaders. The coordinates of the virtual leaders and also the priority to follow the specific leader are calculated by each agent itself according to specific rules.The following results are presented in the article: the base control rule for solving the formation control problem, its modifications for the cases when the number of agents is greater/less than the size of the target geometric formation structure and also the computer modeling results proving the efficiency of the modified control rules. The specific feature of the control rule, developed by the author, is that each agent itself calculates the virtual leaders and each agent performs dynamic choice of the place within the formation (there is no predefined one-to-one relation between agents and places within the geometric formation structure. The results, provided in this article, can be used in robotics for developing control algorithms for the tasks, which require preserving specific relational positions among the agents while moving. One of the

IMPACTS OF BIOFILM FORMATION ON CELLULOSE FERMENTATION

Energy Technology Data Exchange (ETDEWEB)

Leschine, Susan

2009-10-31

This project addressed four major areas of investigation: i) characterization of formation of Cellulomonas uda biofilms on cellulose; ii) characterization of Clostridium phytofermentans biofilm development; colonization of cellulose and its regulation; iii) characterization of Thermobifida fusca biofilm development; colonization of cellulose and its regulation; and iii) description of the architecture of mature C. uda, C. phytofermentans, and T. fusca biofilms. This research is aimed at advancing understanding of biofilm formation and other complex processes involved in the degradation of the abundant cellulosic biomass, and the biology of the microbes involved. Information obtained from these studies is invaluable in the development of practical applications, such as the single-step bioconversion of cellulose-containing residues to fuels and other bioproducts. Our results have clearly shown that cellulose-decomposing microbes rapidly colonize cellulose and form complex structures typical of biofilms. Furthermore, our observations suggest that, as cells multiply on nutritive surfaces during biofilms formation, dramatic cell morphological changes occur. We speculated that morphological changes, which involve a transition from rod-shaped cells to more rounded forms, might be more apparent in a filamentous microbe. In order to test this hypothesis, we included in our research a study of biofilm formation by T. fusca, a thermophilic cellulolytic actinomycete commonly found in compost. The cellulase system of T. fusca has been extensively detailed through the work of David Wilson and colleagues at Cornell, and also, genome sequence of a T. fusca strain has been determine by the DOE Joint Genome Institute. Thus, T. fusca is an excellent subject for studies of biofilm development and its potential impacts on cellulose degradation. We also completed a study of the chitinase system of C. uda. This work provided essential background information for understanding how C. uda

The formation of galaxies

International Nuclear Information System (INIS)

Gunn, J.E.

1983-01-01

The presently fashionable ideas for galaxy formation are reviewed briefly, and it is concluded that the standard isothermal heirarchy fits the available data best. A simple infall picture is presented which explains many of the observed properties of disk galaxies. (orig.)

Complex formation of p-carboxybenzeneboronic acid with fructose

International Nuclear Information System (INIS)

Bulbul Islam, T.M.; Yoshino, K.

2000-01-01

To increase the solubility of p-caboxybenzeneboronic acid (PCBA) in physiological pH 7.4, the complex formation of PCBA with fructose has been studied by 11 B-NMR. PCBA formed complex with fructose and the complex increased the solubility of PCBA. The complex formation constant (log K) was obtained in pH 7.4 as 2.75 from the 11 B-NMR spectra. Based on this result the complex formation ability of PCBA with fructose has been discussed. (author)

Analysis of Contracts in Various Formats of Blockchain

OpenAIRE

Hegadekatti, Kartik

2016-01-01

One of the important features of Blockchain is that it allows the hosting and execution of contracts. Such a contract in the digital world is known as a Smart Contract. But the process and consequences of a contract vary radically from one format of Blockchain to another. One of the formats (and the most common at present) is the Unregulated Blockchain (like Bitcoin and Ethereum) with no government supervision whatsoever. Another format is the Controlled Blockchain which is managed and guaran...

ASDF: An Adaptable Seismic Data Format with Full Provenance

Science.gov (United States)

Smith, J. A.; Krischer, L.; Tromp, J.; Lefebvre, M. P.

2015-12-01

In order for seismologists to maximize their knowledge of how the Earth works, they must extract the maximum amount of useful information from all recorded seismic data available for their research. This requires assimilating large sets of waveform data, keeping track of vast amounts of metadata, using validated standards for quality control, and automating the workflow in a careful and efficient manner. In addition, there is a growing gap between CPU/GPU speeds and disk access speeds that leads to an I/O bottleneck in seismic workflows. This is made even worse by existing seismic data formats that were not designed for performance and are limited to a few fixed headers for storing metadata.The Adaptable Seismic Data Format (ASDF) is a new data format for seismology that solves the problems with existing seismic data formats and integrates full provenance into the definition. ASDF is a self-describing format that features parallel I/O using the parallel HDF5 library. This makes it a great choice for use on HPC clusters. The format integrates the standards QuakeML for seismic sources and StationXML for receivers. ASDF is suitable for storing earthquake data sets, where all waveforms for a single earthquake are stored in a one file, ambient noise cross-correlations, and adjoint sources. The format comes with a user-friendly Python reader and writer that gives seismologists access to a full set of Python tools for seismology. There is also a faster C/Fortran library for integrating ASDF into performance-focused numerical wave solvers, such as SPECFEM3D_GLOBE. Finally, a GUI tool designed for visually exploring the format exists that provides a flexible interface for both research and educational applications. ASDF is a new seismic data format that offers seismologists high-performance parallel processing, organized and validated contents, and full provenance tracking for automated seismological workflows.

Photoionization-regulated star formation and the structure of molecular clouds

Science.gov (United States)

Mckee, Christopher F.

1989-01-01

A model for the rate of low-mass star formation in Galactic molecular clouds and for the influence of this star formation on the structure and evolution of the clouds is presented. The rate of energy injection by newly formed stars is estimated, and the effect of this energy injection on the size of the cloud is determined. It is shown that the observed rate of star formation appears adequate to support the observed clouds against gravitational collapse. The rate of photoionization-regulated star formation is estimated and it is shown to be in agreement with estimates of the observed rate of star formation if the observed molecular cloud parameters are used. The mean cloud extinction and the Galactic star formation rate per unit mass of molecular gas are predicted theoretically from the condition that photionization-regulated star formation be in equilibrium. A simple model for the evolution of isolated molecular clouds is developed.

A review of NOx formation mechanisms in recovery furnaces

International Nuclear Information System (INIS)

Nichols, K.M.; Thompson, L.M.; Empie, H.J.

1993-01-01

Review of NOx formation studies shows that NO forms in recovery furnaces primarily by two independent mechanisms, thermal and fuel. Thermal NO formation is extremely temperature-sensitive. However, theoretical predictions indicate that recovery furnace temperatures are not high enough to form significant thermal NO. Fuel NO formation is less temperature-sensitive, and is related to fuel nitrogen content. Black liquors are shown to contain 0.05 to 0.24 weight percent fuel nitrogen. Conversion of just 20% of this would yield approximately 25-120 ppm NOx (at 8% 0 2 ) in the flue gas, enough to represent the majority of the total NOx. Data from operating recovery furnaces show NOx emissions ranging from near zero to over 100 ppm at 8% 0 2 . An apparent increase in recovery furnace NOx emissions was observed with increasing solids. This increase is much less than predicted by thermal NO formation theory, indicating that other NO formation/destruction mechanisms, such as fuel NO formation, are important. No data are available to show the relative importance of thermal and fuel NO to total NOx during black liquor combustion

ENDF/X: An Extended ENDF Format (Evolution, not Revolution)