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1

Getting to Know Homo erectus  

NSDL National Science Digital Library

Access to the article is free, however registration and sign-in are required. Europe and Asia have yielded a number of hominid fossils from the period 1 to 0.5 million years ago, but few hominid fossils from this era have been found in Africa. In his Perspective, Schwartz discusses a new hominid fossil find at Olorgesailie in Kenya, and whether it belongs to the species Homo erectus.

Jeffrey H. Schwartz (University of Pittsburgh;)

2004-07-02

2

Latest Homo erectus of Java: Potential Contemporaneity with Homo sapiens in Southeast Asia  

Microsoft Academic Search

Hominid fossils from Ngandong and Sambungmacan, Central Java, are considered the most morphologically advanced representatives of Homo erectus. Electron spin resonance (ESR) and mass spectrometric U-series dating of fossil bovid teeth collected from the hominid-bearing levels at these sites gave mean ages of 27 ± 2 to 53.3 ± 4 thousand years ago; the range in ages reflects uncertainties in

C. C. Swisher III; W. J. Rink; S. C. Anton; H. P. Schwarcz; G. H. Curtis; A. Suprijo; Widiasmoro

1996-01-01

3

Mapping and taphonomic analysis of the Homo erectus loci at Locality 1 Zhoukoudian, China  

Microsoft Academic Search

From a detailed analysis of published and unpublished sources, we constructed a digitized three-dimensional, stratigraphically-controlled excavation grid of Zhoukoudian Locality 1 in order to assess the spatial relationships of the excavated materials. All 15 fossil Homo erectus loci were mapped on the grid. Meter cubes were used in excavation starting in 1934, and Loci H through O, established between 1934

Noel T. Boaz; Russell L. Ciochon; Qinqi Xu; Jinyi Liu

2004-01-01

4

Paleo-environmental reconstruction during the period of Nanjing Homo Erectus  

Microsoft Academic Search

Using five-group dating of the fossil by Uranium series age method shows that the age of Nanjing Homo Erectus is between 280–430 ka B. P. Combining with the analysis of fossil mammalian form Stegodon, Sus. Lydekkeri Zdansly, M. pachyosteus Young, P. grayi Zdansky and E. SanmeniensisTeilhard et Pive teau, which are located in the same stratum, the authors thinks that

Cheng Zhu; Yun Zhang

2000-01-01

5

Early Homo erectus skeleton from west Lake Turkana, Kenya.  

PubMed

The most complete early hominid skeleton ever found was discovered at Nariokotome III, west Lake Turkana, Kenya, and excavated in situ in sediments dated close to 1.6 Myr. The specimen, KNM-WT 15000, is a male Homo erectus that died at 12 +/- 1 years of age, as judged by human standards, but was already 1.68 m tall. Although human-like in many respects, this specimen documents important anatomical differences between H. erectus and modern humans for the first time. PMID:3929141

Brown, F; Harris, J; Leakey, R; Walker, A

6

Mapping and taphonomic analysis of the Homo erectus loci at Locality 1 Zhoukoudian, China.  

PubMed

From a detailed analysis of published and unpublished sources, we constructed a digitized three-dimensional, stratigraphically-controlled excavation grid of Zhoukoudian Locality 1 in order to assess the spatial relationships of the excavated materials. All 15 fossil Homo erectus loci were mapped on the grid. Meter cubes were used in excavation starting in 1934, and Loci H through O, established between 1934 and 1937, were mapped to within 1 m(3)vertical and horizontal provenience. Loci A through G, established between 1921 and 1933, were excavated in the northernmost part of Locality 1 by unmapped quarrying, but their stratigraphic levels were recorded. We could localize Loci A through G on the grid system by utilizing locations of remaining walls, stratigraphic sections, excavation reports, excavation maps, and photographs. Loci contained skeletal elements of Homo erectus individuals scattered over areas of the cave floor of up to 9 m in diameter. Scoring of taphonomic damage on the Homo erectus sample, as observed on casts and originals, demonstrates that 67% of the hominid sample shows bite marks or other modifications ascribed to large mammalian carnivores, particularly the large Pleistocene cave hyena, Pachycrocuta brevirostris. Virtually all of the remaining Homo erectus skeletal assemblage shows breakage consistent with this taphonomic pattern of fragmentation. Bioturbation by digging carnivores is the most likely explanation for a fragment of Homo erectus Skull XI discovered 1 m below its other conjoined portions in Locus L. Carbon on all the Homo erectus fossils from Locus G, a circumscribed area of 1-meter diameter, earlier taken to indicate burning, cooking, and cannibalism, is here interpreted as detrital carbon deposited under water, perhaps the result of hyaenid caching behavior. Locus G records the close stratigraphic and horizontal association of stone artifacts with Homo erectus and other vertebrate skeletal elements, an association that is seen at other loci as well. Layer 4 of the excavation contains equid cranial bone previously interpreted to have been burned while fresh. We here document that Locus B Homo erectus, including Skull I, is stratigraphically associated with this evidence, but at some 10-12 m distance. Even though the presence of wood-stoked fires and hearths is not supported by geochemical results, evidence of fire at Locality 1 in the form of burned bone is confirmed. Contextual relationships of fossil skeletal elements, relationships of carnivore damage and stone tool cutmarks on bone, and evidence of the burning of fresh bone associated with Homo erectus and stone tools support a model of transient hominid scavenging aided by the use of fire at the large hyenid den that became Zhoukoudian Locality 1. Although the original excavation catalogue from Locality 1, as well as a significant number of fossils and stone artifacts, were lost during World War II, catalogue numbers on the many surviving specimens can be used to locate fossils and artifacts within the three-dimensional grid provided in this paper. PMID:15120264

Boaz, Noel T; Ciochon, Russell L; Xu, Qinqi; Liu, Jinyi

2004-05-01

7

Clavicle length, throwing performance and the reconstruction of the Homo erectus shoulder.  

PubMed

Powerful, accurate throwing may have been an important mode of early hunting and defense. Previous work has shown that throwing performance is functionally linked to several anatomical shifts in the upper body that occurred during human evolution. The final shift to occur is the inferior reorientation of the shoulder. Fossil scapulae show the earliest evidence of a more inferior glenoid in Homo erectus. However, where the scapula rests on the thorax is uncertain. The relative length of the clavicle, the only skeletal attachment of the scapula to the torso, is quite variable. Depending on which fossils or skeletal measures are used to reconstruct the H. erectus shoulder, either a novel, anteriorly facing shoulder configuration or a modern human-like lateral orientation is possible. These competing hypotheses have led to very different conclusions regarding the throwing ability and hunting behavior of early Homo. Here, we evaluate competing models of H. erectus shoulder morphology and examine how these models relate to throwing performance. To address these questions, we collected skeletal measures from fossil and extant taxa, as well as anthropometric (N = 36) and kinematic (N = 27) data from Daasanach throwers from northwestern Kenya. Our data show that all H. erectus fossil clavicles fall within the normal range of modern human variation. We find that a commonly used metric for normalizing clavicle length, the claviculohumeral ratio, poorly predicts shoulder position on the torso. Furthermore, no significant relationship between clavicle length and any measure of throwing performance was found. These data support reconstructing the H. erectus shoulder as modern human-like, with a laterally facing glenoid, and suggest that the capacity for high speed throwing dates back nearly two million years. PMID:25439706

Roach, Neil T; Richmond, Brian G

2014-11-01

8

Early Homo erectus skeleton from west Lake Turkana, Kenya  

Microsoft Academic Search

The most complete early hominid skeleton ever found was discovered at Nariokotome III, west Lake Turkana, Kenya, and excavated in situ in sediments dated close to 1.6 Myr. The specimen, KNM-WT 15000, is a male Homo erectus that died at 12 +\\/- 1 years of age, as judged by human standards, but was already 1.68 m tall. Although human-like in

Frank Brown; John Harris; Richard Leakey; Alan Walker

1985-01-01

9

Homo erectus at Trinil on Java used shells for tool production and engraving.  

PubMed

The manufacture of geometric engravings is generally interpreted as indicative of modern cognition and behaviour. Key questions in the debate on the origin of such behaviour are whether this innovation is restricted to Homo sapiens, and whether it has a uniquely African origin. Here we report on a fossil freshwater shell assemblage from the Hauptknochenschicht ('main bone layer') of Trinil (Java, Indonesia), the type locality of Homo erectus discovered by Eugène Dubois in 1891 (refs 2 and 3). In the Dubois collection (in the Naturalis museum, Leiden, The Netherlands) we found evidence for freshwater shellfish consumption by hominins, one unambiguous shell tool, and a shell with a geometric engraving. We dated sediment contained in the shells with (40)Ar/(39)Ar and luminescence dating methods, obtaining a maximum age of 0.54 ± 0.10 million years and a minimum age of 0.43 ± 0.05 million years. This implies that the Trinil Hauptknochenschicht is younger than previously estimated. Together, our data indicate that the engraving was made by Homo erectus, and that it is considerably older than the oldest geometric engravings described so far. Although it is at present not possible to assess the function or meaning of the engraved shell, this discovery suggests that engraving abstract patterns was in the realm of Asian Homo erectus cognition and neuromotor control. PMID:25470048

Joordens, Josephine C A; d'Errico, Francesco; Wesselingh, Frank P; Munro, Stephen; de Vos, John; Wallinga, Jakob; Ankjærgaard, Christina; Reimann, Tony; Wijbrans, Jan R; Kuiper, Klaudia F; Mücher, Herman J; Coqueugniot, Hélène; Prié, Vincent; Joosten, Ineke; van Os, Bertil; Schulp, Anne S; Panuel, Michel; van der Haas, Victoria; Lustenhouwer, Wim; Reijmer, John J G; Roebroeks, Wil

2015-02-12

10

African Homo erectus: old radiometric ages and young Oldowan assemblages in the Middle Awash Valley, Ethiopia.  

PubMed

Fossils and artifacts recovered from the middle Awash Valley of Ethiopia's Afar depression sample the Middle Pleistocene transition from Homo erectus to Homo sapiens. Ar/Ar ages, biostratigraphy, and tephrachronology from this area indicate that the Pleistocene Bodo hominid cranium and newer specimens are approximately 0.6 million years old. Only Oldowan chopper and flake assemblages are present in the lower stratigraphic units, but Acheulean bifacial artifacts are consistently prevalent and widespread in directly overlying deposits. This technological transition is related to a shift in sedimentary regime, supporting the hypothesis that Middle Pleistocene Oldowan assemblages represent a behavioral facies of the Acheulean industrial complex. PMID:8009220

Clark, J D; de Heinzelin, J; Schick, K D; Hart, W K; White, T D; WoldeGabriel, G; Walter, R C; Suwa, G; Asfaw, B; Vrba, E

1994-06-24

11

Grandmothering and the evolution of Homo erectus  

Microsoft Academic Search

Despite recent, compelling challenge, the evolution ofHomo erectusis still commonly attributed to big game hunting and\\/or scavenging and family provisioning by men. Here we use a version of the “grandmother” hypothesis to develop an alternative scenario, that climate-driven adjustments infemaleforaging and food sharing practices, possibly involving tubers, favored significant changes in ancestral life history, morphology, and ecology leading to the

J. F. O’Connell; K. Hawkes; N. G. Blurton Jones

1999-01-01

12

Molar crown inner structural organization in Javanese Homo erectus.  

PubMed

This contribution investigates the inner organizational pattern (tooth tissue proportions and enamel-dentine junction morphology) of seven Homo erectus permanent molar crowns from the late Lower-early Middle Pleistocene Kabuh Formation of the Sangiran Dome (Central Java, Indonesia). The previous study of their external characteristics confirmed the degree of time-related structural reduction occurred in Javanese H. erectus, and also revealed a combination of nonmetric features which are rare in the Lower and early Middle Pleistocene dental record, but more frequently found in recent humans. In accordance with their outer occlusal morphology, the specimens exhibit a set of derived internal features, such as thick to hyperthick enamel, an incomplete expression of the crest patterns at the enamel-dentine junction (EDJ) level, a sharp EDJ topography. As a whole, these features differ from those expressed in some penecontemporaneous specimens/samples representing African H. erectus/ergaster and H. heidelbergensis, as well as in Neanderthals, but occur in recent human populations. Further research in virtual dental paleoanthropology to be developed at macroregional scale would clarify the polarity and intensity of the intermittent exchanges between continental and insular Southeast Asia around the Lower to Middle Pleistocene boundary, as well as should shed light on the still poorly understood longitudinal evolutionary dynamics across continental Asia. Am J Phys Anthropol 156:148-157, 2015 © 2014 Wiley Periodicals, Inc. PMID:25209431

Zanolli, Clément

2015-01-01

13

Paleoanthropology: Homo erectus and the limits of a paleontological species.  

PubMed

The bushy nature of the human evolutionary tree in the past 3 million years is widely accepted. Yet, a spectacular new fossil of early Homo has prompted some paleoanthropologists to prune our family tree. PMID:24456983

Hublin, Jean-Jacques

2014-01-20

14

Dating the Homo erectus bearing travertine from Kocaba? (Denizli, Turkey) at at least 1.1 Ma  

NASA Astrophysics Data System (ADS)

Since its discovery within a travertine quarry, the fragmentary cranium of the only known Turkish Homo erectus, the Kocaba? hominid, has led to conflicting biochronological estimations. First estimated to be ˜500 ka old, the partial skull presents a combination of archaic and evolved features that puts it as an intermediate specimen between the Dmanisi fossils (Homo georgicus) and the Chinese Zhoukoudian skulls (Homo erectus) respectively dated to 1.8 to ˜0.8 Ma. Here we present a multidisciplinary study combining sedimentological, paleontological and paleoanthropological observations together with cosmogenic nuclide concentration and paleomagnetic measurements to provide an absolute chronological framework for the Upper fossiliferous Travertine unit where the Kocaba? hominid and fauna were discovered. The 26Al/10Be burial ages determined on pebbles from conglomeratic levels framing the Upper fossiliferous Travertine unit, which exhibits an inverse polarity, constrains its deposition to before the Cobb Mountain sub-chron, that is between 1.22 and ˜1.5 Ma. The alternative match of the normal polarity recorded above the travertine with the Jaramillo subchron (lower limit 1.07 Ma) may also be marginally compatible with cosmogenic nuclides interpretation, thus the proposed minimum age of 1.1 Ma for the end of massive travertine deposition. The actual age of the fossils is likely to be in the 1.1-1.3 Ma range. This absolute date is in close agreement with the paleoanthropological conclusions based on morphometric comparisons implying that Kocaba? hominid belongs to the Homo erectus s.l. group that includes Chinese and African fossils, and is different from Middle and Upper Pleistocene specimens. Furthermore, this date is confirmed by the large mammal assemblage, typical of the late Villafranchian. Because it attests to the antiquity of human occupation of the Anatolian Peninsula and one of the waves of settlements out of Africa, this work challenges the current knowledge of the Homo erectus dispersal over Eurasia.

Lebatard, Anne-Elisabeth; Alçiçek, M. Cihat; Rochette, Pierre; Khatib, Samir; Vialet, Amélie; Boulbes, Nicolas; Bourlès, Didier L.; Demory, François; Guipert, Gaspard; Mayda, Serdar; Titov, Vadim V.; Vidal, Laurence; de Lumley, Henry

2014-03-01

15

Discovery of Postcranial Remains of Homo erectus and Associated Artefacts in Bed IV at Olduvai Gorge, Tanzania  

Microsoft Academic Search

The discovery of a left femur shaft and hip bone of Homo erectus in association with an Acheulean industry in Bed IV represents the first direct association at Olduvai of a well defined artefact assemblage with H. erectus.

M. D. Leakey

1971-01-01

16

New dating of the Homo erectus cranium from Lantian (Gongwangling), China.  

PubMed

The Homo erectus cranium from Gongwangling, Lantian County, Shaanxi Province is the oldest fossil hominin specimen from North China. It was found in 1964 in a layer below the Jaramillo subchron and was attributed to loess (L) L15 in the Chinese loess-palaeosol sequence, with an estimated age of ca. 1.15 Ma (millions of years ago). Here, we demonstrate that there is a stratigraphical hiatus in the Gongwangling section immediately below loess 15, and the cranium in fact lies in palaeosol (S) S22 or S23, the age of which is ca. 1.54-1.65 Ma. Closely spaced palaeomagnetic sampling at two sections at Gongwangling and one at Jiacun, 10 km to the north, indicate that the fossil layer at Gongwangling and a similar fossil horizon at Jiacun were deposited shortly before a short period of normal polarity above the Olduvai subchron. This is attributed to the Gilsa Event that has been dated elsewhere to ca. 1.62 Ma. Our investigations thus demonstrate that the Gongwangling cranium is slightly older than ca. 1.62 Ma, probably ca. 1.63 Ma, and significantly older than previously supposed. This re-dating now makes Gongwangling the second oldest site outside Africa (after Dmanisi) with cranial remains, and causes substantial re-adjustment in the early fossil hominin record in Eurasia. PMID:25456822

Zhu, Zhao-Yu; Dennell, Robin; Huang, Wei-Wen; Wu, Yi; Rao, Zhi-Guo; Qiu, Shi-Fan; Xie, Jiu-Bing; Liu, Wu; Fu, Shu-Qing; Han, Jiang-Wei; Zhou, Hou-Yun; Ou Yang, Ting-Ping; Li, Hua-Mei

2015-01-01

17

The taxonomic implications of cranial shape variation in Homo erectus Karen L. Baab  

E-print Network

to Homo erectus sensu lato (s.l.). These more recent discoveries from the Caucasus, East Africa, and Asia in the west, to the Caucasus in the north, and China and Java in the east (Right- mire, 1984, 1990, 1998; Bra

Baab, Karen L.

18

No skeletal dysplasia in the Nariokotome boy KNM-WT 15000 (Homo erectus)--a reassessment of congenital pathologies of the vertebral column.  

PubMed

The Nariokotome boy skeleton KNM-WT 15000 is the most complete Homo erectus fossil and therefore is key for understanding human evolution. Nevertheless, since Latimer and Ohman (2001) reported on severe congenital pathology in KNM-WT 15000, it is questionable whether this skeleton can still be used as reference for Homo erectus skeletal biology. The asserted pathologies include platyspondylic and diminutive vertebrae implying a disproportionately short stature; spina bifida; condylus tertius; spinal stenosis; and scoliosis. Based on this symptom complex, the differential diagnosis of spondyloepiphyseal dysplasia tarda, an extremely rare form of skeletal dysplasia, has been proposed. Yet, our reanalysis of these pathologies shows that the shape of the KNM-WT 15000 vertebrae matches that of normal modern human adolescents. The vertebrae are not abnormally flat, show no endplate irregularities, and thus are not platyspondylic. As this is the hallmark of spondyloepiphyseal dysplasia tarda and related forms of skeletal dysplasia, the absence of platyspondyly refutes axial dysplasia and disproportionate dwarfism. Furthermore, we neither found evidence for spina bifida occulta nor manifesta, whereas the condylus tertius, a developmental anomaly of the cranial base, is not related to skeletal dysplasias. Other fossils indicate that the relatively small size of the vertebrae and the narrow spinal canal are characteristics of early hominins rather than congenital pathologies. Except for the recently described signs of traumatic lumbar disc herniation, the Nariokotome boy fossil therefore seems to belong to a normal Homo erectus youth without pathologies of the axial skeleton. PMID:23283736

Schiess, Regula; Haeusler, Martin

2013-03-01

19

Hominid mandibular corpus shape variation and its utility for recognizing species diversity within fossil Homo  

PubMed Central

Mandibular corpora are well represented in the hominin fossil record, yet few studies have rigorously assessed the utility of mandibular corpus morphology for species recognition, particularly with respect to the linear dimensions that are most commonly available. In this study, we explored the extent to which commonly preserved mandibular corpus morphology can be used to: (i) discriminate among extant hominid taxa and (ii) support species designations among fossil specimens assigned to the genus Homo. In the first part of the study, discriminant analysis was used to test for significant differences in mandibular corpus shape at different taxonomic levels (genus, species and subspecies) among extant hominid taxa (i.e. Homo, Pan, Gorilla, Pongo). In the second part of the study, we examined shape variation among fossil mandibles assigned to Homo(including H. habilis sensu stricto, H. rudolfensis, early African H. erectus/H. ergaster, late African H. erectus, Asian H. erectus, H. heidelbergensis, H. neanderthalensis and H. sapiens). A novel randomization procedure designed for small samples (and using group ‘distinctness values’) was used to determine whether shape variation among the fossils is consistent with conventional taxonomy (or alternatively, whether a priori taxonomic groupings are completely random with respect to mandibular morphology). The randomization of ‘distinctness values’ was also used on the extant samples to assess the ability of the test to recognize known taxa. The discriminant analysis results demonstrated that, even for a relatively modest set of traditional mandibular corpus measurements, we can detect significant differences among extant hominids at the genus and species levels, and, in some cases, also at the subspecies level. Although the randomization of ‘distinctness values’ test is more conservative than discriminant analysis (based on comparisons with extant specimens), we were able to detect at least four distinct groups among the fossil specimens (i.e. H. sapiens, H. heidelbergensis, Asian H. erectus and a combined ‘African Homo’ group consisting of H. habilis sensu stricto, H. rudolfensis, early African H. erectus/H. ergaster and late African H. erectus). These four groups appear to be distinct at a level similar to, or greater than, that of modern hominid species. In addition, the mandibular corpora of H. neanderthalensis could be distinguished from those of ‘African Homo’, although not from those of H. sapiens, H. heidelbergensis, or the Asian H. erectus group. The results suggest that the features most commonly preserved on the hominin mandibular corpus have some taxonomic utility, although they are unlikely to be useful in generating a reliable alpha taxonomy for early African members of the genus Homo. PMID:19094183

Lague, Michael R; Collard, Nicole J; Richmond, Brian G; Wood, Bernard A

2008-01-01

20

Implications of new early Homo fossils from Ileret, east of Lake Turkana, Kenya.  

PubMed

Sites in eastern Africa have shed light on the emergence and early evolution of the genus Homo. The best known early hominin species, H. habilis and H. erectus, have often been interpreted as time-successive segments of a single anagenetic evolutionary lineage. The case for this was strengthened by the discovery of small early Pleistocene hominin crania from Dmanisi in Georgia that apparently provide evidence of morphological continuity between the two taxa. Here we describe two new cranial fossils from the Koobi Fora Formation, east of Lake Turkana in Kenya, that have bearing on the relationship between species of early Homo. A partial maxilla assigned to H. habilis reliably demonstrates that this species survived until later than previously recognized, making an anagenetic relationship with H. erectus unlikely. The discovery of a particularly small calvaria of H. erectus indicates that this taxon overlapped in size with H. habilis, and may have shown marked sexual dimorphism. The new fossils confirm the distinctiveness of H. habilis and H. erectus, independently of overall cranial size, and suggest that these two early taxa were living broadly sympatrically in the same lake basin for almost half a million years. PMID:17687323

Spoor, F; Leakey, M G; Gathogo, P N; Brown, F H; Antón, S C; McDougall, I; Kiarie, C; Manthi, F K; Leakey, L N

2007-08-01

21

Homo floresiensis Contextualized: A Geometric Morphometric Comparative Analysis of Fossil and Pathological Human Samples  

PubMed Central

The origin of hominins found on the remote Indonesian island of Flores remains highly contentious. These specimens may represent a new hominin species, Homo floresiensis, descended from a local population of Homo erectus or from an earlier (pre-H. erectus) migration of a small-bodied and small-brained hominin out of Africa. Alternatively, some workers suggest that some or all of the specimens recovered from Liang Bua are pathological members of a small-bodied modern human population. Pathological conditions proposed to explain their documented anatomical features include microcephaly, myxoedematous endemic hypothyroidism (“cretinism”) and Laron syndrome (primary growth hormone insensitivity). This study evaluates evolutionary and pathological hypotheses through comparative analysis of cranial morphology. Geometric morphometric analyses of landmark data show that the sole Flores cranium (LB1) is clearly distinct from healthy modern humans and from those exhibiting hypothyroidism and Laron syndrome. Modern human microcephalic specimens converge, to some extent, on crania of extinct species of Homo. However in the features that distinguish these two groups, LB1 consistently groups with fossil hominins and is most similar to H. erectus. Our study provides further support for recognizing the Flores hominins as a distinct species, H. floresiensis, whose affinities lie with archaic Homo. PMID:23874886

Baab, Karen L.; McNulty, Kieran P.; Harvati, Katerina

2013-01-01

22

New vertebral and rib material point to modern bauplan of the Nariokotome Homo erectus skeleton.  

PubMed

The double S shape of the vertebral column is one of the most important evolutionary adaptations to human bipedal locomotion, providing an optimal compromise between stability and mobility. It is commonly believed that a six element long lumbar spine facilitated the critical adoption of lumbar lordosis in early hominins, which contrasts with five lumbars in modern humans and four in chimpanzees and gorillas. This is mainly based on the juvenile Homo erectus skeleton KNM-WT 15000 from Nariokotome, Kenya. Yet, the biomechanical advantage of a long lumbar spine is speculative. Here we present new vertebral and rib fragments of KNM-WT 15000. They demonstrate that the sixth to the last presacral vertebra possesses rib facets and therefore indicate the presence of only five lumbar and twelve thoracic segments, as is characteristic of modern humans. Moreover, they show that no additional element was located between the sixth to the last presacral vertebra and Th11 as suggested in the original description. The transition from thoracic to lumbar type orientation of the facet joints that takes place at Th11 is thus at the same segment as in over 40% of modern humans, suggesting an identical lumbar mobility and capacity for lordosis. Taken together, KNM-WT 15000 had one vertebra less than previously thought irrespective of whether rib-free lumbar vertebrae or vertebrae that bear lumbar-like articular processes are counted. Furthermore, the new rib fragments imply a rearrangement of the ribs that results in a symmetrical rib cage. This challenges previous claims for idiopathic or congenital scoliosis. We conclude that the bauplan of the hominin axial skeleton is more conservative than previously thought. PMID:21868059

Haeusler, Martin; Schiess, Regula; Boeni, Thomas

2011-11-01

23

The Age of the 20 Meter Solo River Terrace, Java, Indonesia and the Survival of Homo erectus in Asia  

PubMed Central

Homo erectus was the first human lineage to disperse widely throughout the Old World, the only hominin in Asia through much of the Pleistocene, and was likely ancestral to H. sapiens. The demise of this taxon remains obscure because of uncertainties regarding the geological age of its youngest populations. In 1996, some of us co-published electron spin resonance (ESR) and uranium series (U-series) results indicating an age as young as 35–50 ka for the late H. erectus sites of Ngandong and Sambungmacan and the faunal site of Jigar (Indonesia). If correct, these ages favor an African origin for recent humans who would overlap with H. erectus in time and space. Here, we report 40Ar/39Ar incremental heating analyses and new ESR/U-series age estimates from the “20 m terrace" at Ngandong and Jigar. Both data sets are internally consistent and provide no evidence for reworking, yet they are inconsistent with one another. The 40Ar/39Ar analyses give an average age of 546±12 ka (sd±5 se) for both sites, the first reliable radiometric indications of a middle Pleistocene component for the terrace. Given the technical accuracy and consistency of the analyses, the argon ages represent either the actual age or the maximum age for the terrace and are significantly older than previous estimates. Most of the ESR/U-series results are older as well, but the oldest that meets all modeling criteria is 143 ka+20/?17. Most samples indicated leaching of uranium and likely represent either the actual or the minimum age of the terrace. Given known sources of error, the U-series results could be consistent with a middle Pleistocene age. However, the ESR and 40Ar/39Ar ages preclude one another. Regardless, the age of the sites and hominins is at least bracketed between these estimates and is older than currently accepted. PMID:21738710

Indriati, Etty; Swisher, Carl C.; Lepre, Christopher; Quinn, Rhonda L.; Suriyanto, Rusyad A.; Hascaryo, Agus T.; Grün, Rainer; Feibel, Craig S.; Pobiner, Briana L.; Aubert, Maxime; Lees, Wendy; Antón, Susan C.

2011-01-01

24

High-resolution record of the Matuyama–Brunhes transition constrains the age of Javanese Homo erectus in the Sangiran dome, Indonesia  

PubMed Central

A detailed paleomagnetic study conducted in the Sangiran area, Java, has provided a reliable age constraint on hominid fossil-bearing formations. A reverse-to-normal polarity transition marks a 7-m thick section across the Upper Tuff in the Bapang Formation. The transition has three short reversal episodes and is overlain by a thick normal polarity magnetozone that was fission-track dated to the Brunhes chron. This pattern closely resembles another high-resolution Matuyama–Brunhes (MB) transition record in an Osaka Bay marine core. In the Sangiran sediments, four successive transitional polarity fields lie just below the presumed main MB boundary. Their virtual geomagnetic poles cluster in the western South Pacific, partly overlapping the transitional virtual geomagnetic poles from Hawaiian and Canary Islands’ lavas, which have a mean 40Ar/39Ar age of 776 ± 2 ka. Thus, the polarity transition is unambiguously the MB boundary. A revised correlation of tuff layers in the Bapang Formation reveals that the hominid last occurrence and the tektite level in the Sangiran area are nearly coincident, just below the Upper Middle Tuff, which underlies the MB transition. The stratigraphic relationship of the tektite level to the MB transition in the Sangiran area is consistent with deep-sea core data that show that the meteorite impact preceded the MB reversal by about 12 ka. The MB boundary currently defines the uppermost horizon yielding Homo erectus fossils in the Sangiran area. PMID:22106291

Hyodo, Masayuki; Matsu'ura, Shuji; Kamishima, Yuko; Kondo, Megumi; Takeshita, Yoshihiro; Kitaba, Ikuko; Danhara, Tohru; Aziz, Fachroel; Kurniawan, Iwan; Kumai, Hisao

2011-01-01

25

High-resolution record of the Matuyama-Brunhes transition constrains the age of Javanese Homo erectus in the Sangiran dome, Indonesia.  

PubMed

A detailed paleomagnetic study conducted in the Sangiran area, Java, has provided a reliable age constraint on hominid fossil-bearing formations. A reverse-to-normal polarity transition marks a 7-m thick section across the Upper Tuff in the Bapang Formation. The transition has three short reversal episodes and is overlain by a thick normal polarity magnetozone that was fission-track dated to the Brunhes chron. This pattern closely resembles another high-resolution Matuyama-Brunhes (MB) transition record in an Osaka Bay marine core. In the Sangiran sediments, four successive transitional polarity fields lie just below the presumed main MB boundary. Their virtual geomagnetic poles cluster in the western South Pacific, partly overlapping the transitional virtual geomagnetic poles from Hawaiian and Canary Islands' lavas, which have a mean (40)Ar/(39)Ar age of 776 ± 2 ka. Thus, the polarity transition is unambiguously the MB boundary. A revised correlation of tuff layers in the Bapang Formation reveals that the hominid last occurrence and the tektite level in the Sangiran area are nearly coincident, just below the Upper Middle Tuff, which underlies the MB transition. The stratigraphic relationship of the tektite level to the MB transition in the Sangiran area is consistent with deep-sea core data that show that the meteorite impact preceded the MB reversal by about 12 ka. The MB boundary currently defines the uppermost horizon yielding Homo erectus fossils in the Sangiran area. PMID:22106291

Hyodo, Masayuki; Matsu'ura, Shuji; Kamishima, Yuko; Kondo, Megumi; Takeshita, Yoshihiro; Kitaba, Ikuko; Danhara, Tohru; Aziz, Fachroel; Kurniawan, Iwan; Kumai, Hisao

2011-12-01

26

Implications of new early Homo fossils from Ileret, east of Lake Turkana, Kenya  

Microsoft Academic Search

Sites in eastern Africa have shed light on the emergence and early evolution of the genus Homo. The best known early hominin species, H.habilis and H.erectus, have often been interpreted as time-successive segments of a single anagenetic evolutionary lineage. The case for this was strengthened by the discovery of small early Pleistocene hominin crania from Dmanisi in Georgia that apparently

F. Spoor; M. G. Leakey; P. N. Gathogo; F. H. Brown; S. C. Antón; I. McDougall; C. Kiarie; F. K. Manthi; L. N. Leakey

2007-01-01

27

Man the Fat Hunter: The Demise of Homo erectus and the Emergence of a New Hominin Lineage in the Middle Pleistocene (ca. 400 kyr) Levant  

PubMed Central

The worldwide association of H. erectus with elephants is well documented and so is the preference of humans for fat as a source of energy. We show that rather than a matter of preference, H. erectus in the Levant was dependent on both elephants and fat for his survival. The disappearance of elephants from the Levant some 400 kyr ago coincides with the appearance of a new and innovative local cultural complex – the Levantine Acheulo-Yabrudian and, as is evident from teeth recently found in the Acheulo-Yabrudian 400-200 kyr site of Qesem Cave, the replacement of H. erectus by a new hominin. We employ a bio-energetic model to present a hypothesis that the disappearance of the elephants, which created a need to hunt an increased number of smaller and faster animals while maintaining an adequate fat content in the diet, was the evolutionary drive behind the emergence of the lighter, more agile, and cognitively capable hominins. Qesem Cave thus provides a rare opportunity to study the mechanisms that underlie the emergence of our post-erectus ancestors, the fat hunters. PMID:22174868

Ben-Dor, Miki; Gopher, Avi; Hershkovitz, Israel; Barkai, Ran

2011-01-01

28

Man the fat hunter: the demise of Homo erectus and the emergence of a new hominin lineage in the Middle Pleistocene (ca. 400 kyr) Levant.  

PubMed

The worldwide association of H. erectus with elephants is well documented and so is the preference of humans for fat as a source of energy. We show that rather than a matter of preference, H. erectus in the Levant was dependent on both elephants and fat for his survival. The disappearance of elephants from the Levant some 400 kyr ago coincides with the appearance of a new and innovative local cultural complex--the Levantine Acheulo-Yabrudian and, as is evident from teeth recently found in the Acheulo-Yabrudian 400-200 kyr site of Qesem Cave, the replacement of H. erectus by a new hominin. We employ a bio-energetic model to present a hypothesis that the disappearance of the elephants, which created a need to hunt an increased number of smaller and faster animals while maintaining an adequate fat content in the diet, was the evolutionary drive behind the emergence of the lighter, more agile, and cognitively capable hominins. Qesem Cave thus provides a rare opportunity to study the mechanisms that underlie the emergence of our post-erectus ancestors, the fat hunters. PMID:22174868

Ben-Dor, Miki; Gopher, Avi; Hershkovitz, Israel; Barkai, Ran

2011-01-01

29

The first archaic Homo from Taiwan.  

PubMed

Recent studies of an increasing number of hominin fossils highlight regional and chronological diversities of archaic Homo in the Pleistocene of eastern Asia. However, such a realization is still based on limited geographical occurrences mainly from Indonesia, China and Russian Altai. Here we describe a newly discovered archaic Homo mandible from Taiwan (Penghu 1), which further increases the diversity of Pleistocene Asian hominins. Penghu 1 revealed an unexpectedly late survival (younger than 450 but most likely 190-10 thousand years ago) of robust, apparently primitive dentognathic morphology in the periphery of the continent, which is unknown among the penecontemporaneous fossil records from other regions of Asia except for the mid-Middle Pleistocene Homo from Hexian, Eastern China. Such patterns of geographic trait distribution cannot be simply explained by clinal geographic variation of Homo erectus between northern China and Java, and suggests survival of multiple evolutionary lineages among archaic hominins before the arrival of modern humans in the region. PMID:25625212

Chang, Chun-Hsiang; Kaifu, Yousuke; Takai, Masanaru; Kono, Reiko T; Grün, Rainer; Matsu'ura, Shuji; Kinsley, Les; Lin, Liang-Kong

2015-01-01

30

The first archaic Homo from Taiwan  

PubMed Central

Recent studies of an increasing number of hominin fossils highlight regional and chronological diversities of archaic Homo in the Pleistocene of eastern Asia. However, such a realization is still based on limited geographical occurrences mainly from Indonesia, China and Russian Altai. Here we describe a newly discovered archaic Homo mandible from Taiwan (Penghu 1), which further increases the diversity of Pleistocene Asian hominins. Penghu 1 revealed an unexpectedly late survival (younger than 450 but most likely 190–10 thousand years ago) of robust, apparently primitive dentognathic morphology in the periphery of the continent, which is unknown among the penecontemporaneous fossil records from other regions of Asia except for the mid-Middle Pleistocene Homo from Hexian, Eastern China. Such patterns of geographic trait distribution cannot be simply explained by clinal geographic variation of Homo erectus between northern China and Java, and suggests survival of multiple evolutionary lineages among archaic hominins before the arrival of modern humans in the region. PMID:25625212

Chang, Chun-Hsiang; Kaifu, Yousuke; Takai, Masanaru; Kono, Reiko T.; Grün, Rainer; Matsu’ura, Shuji; Kinsley, Les; Lin, Liang-Kong

2015-01-01

31

Improved age control on early Homo fossils from the upper Burgi Member at Koobi Fora, Kenya.  

PubMed

To address questions regarding the evolutionary origin, radiation and dispersal of the genus Homo, it is crucial to be able to place the occurrence of hominin fossils in a high-resolution chronological framework. The period around 2 Ma (millions of years ago) in eastern Africa is of particular interest as it is at this time that a more substantial fossil record of the genus Homo is first found. Here we combine magnetostratigraphy and strontium (Sr) isotope stratigraphy to improve age control on hominin-bearing upper Burgi (UBU) deposits in Areas 105 and 131 on the Karari Ridge in the eastern Turkana Basin (Kenya). We identify the base of the Olduvai subchron (bC2n) plus a short isolated interval of consistently normal polarity that we interpret to be the Pre-Olduvai event. Combined with precession-forced (~20 kyr [thousands of years]) wet-dry climate cycles resolved by Sr isotope ratios, the magnetostratigraphic data allow us to construct an age model for the UBU deposits. We provide detailed age constraints for 15 hominin fossils from Area 131, showing that key specimens such as cranium KNM-ER 1470, partial face KNM-ER 62000 and mandibles KNM-ER 1482, KNM-ER 1801, and KNM-ER 1802 can be constrained between 1.945 ± 0.004 and 2.058 ± 0.034 Ma, and thus older than previously estimated. The new ages are consistent with a temporal overlap of two species of early Homo that can be distinguished by their facial morphology. Further, our results show that in this time interval, hominins occurred throughout the wet-dry climate cycles, supporting the hypothesis that the lacustrine Turkana Basin was a refugium during regionally dry periods. By establishing the observed first appearance datum of a marine-derived stingray in UBU deposits at 2.058 ± 0.034 Ma, we show that at this time the Turkana Basin was hydrographically connected to the Indian Ocean, facilitating dispersal of fauna between these areas. From a biogeographical perspective, we propose that the Indian Ocean coastal strip should be considered as a possible source area for one or more of the multiple Homo species in the Turkana Basin from over 2 Ma onwards. PMID:24134960

Joordens, Josephine C A; Dupont-Nivet, Guillaume; Feibel, Craig S; Spoor, Fred; Sier, Mark J; van der Lubbe, Jeroen H J L; Nielsen, Trine Kellberg; Knul, Monika V; Davies, Gareth R; Vonhof, Hubert B

2013-12-01

32

Dead Men Telling Tales: Homo Fossils and What to Do With Them  

Microsoft Academic Search

“Human Paleobiology” is about the use of fossils to determine the adaptations and evolutionary trajectories of human ancestors. At least part of this book’s purpose may be summed up in its title; this is Paleobiology, the study of long dead organisms via their fossils, as opposed to Paleoanthropology, the physical anthropology of dead people. Consequently, this book draws attention to

Ben Jeffares

2004-01-01

33

Early evidence of the genus Homo in East Asia.  

PubMed

The timing and route of the earliest dispersal from Africa to Eastern Asia are contentious topics in the study of early human evolution because Asian hominin fossil sites with precise age constraints are very limited. Here we report new high-resolution magnetostratigraphic results that place stringent age controls on excavated hominin incisors and stone tools from the Yuanmou Basin, southwest China. The hominin-bearing layer resides in a reverse polarity magnetozone just above the upper boundary of the Olduvai subchron, yielding an estimated age of 1.7Ma. The finding represents the age of the earliest documented presence of Homo, with affinities to Homo erectus, in mainland East Asia. This age estimate is roughly the same as for H. erectus in island Southeast Asia and immediately prior to the oldest archaeological evidence in northeast Asia. Mammalian fauna and pollen obtained directly from the hominin site indicate that the Yuanmou hominins lived in a varied habitat of open vegetation with patches of bushland and forest on an alluvial fan close to a lake or swamp. The age and location are consistent with a rapid southern migration route of initial hominin populations into Eastern Asia. PMID:18842287

Zhu, R X; Potts, R; Pan, Y X; Yao, H T; Lü, L Q; Zhao, X; Gao, X; Chen, L W; Gao, F; Deng, C L

2008-12-01

34

Fossil humans 1 Fossil humans  

E-print Network

Fossil humans 1 Fossil humans All prehistoric skeletal remains of humans which are archeologically or fossilization of bone, and regardless of whether the remains may be classed as Homo sapi- ens sapiens of the Neanderthal speci- men in 1856. Fossil human remains have come prin- cipally from Europe, Asia, China, Java

Delson, Eric

35

Fossils  

NSDL National Science Digital Library

This Topic in Depth begins with a Web site from the Royal Ontario Museum called Fossils!-Behind the Scenes at the Museum (1). It gives a light-hearted but informative introduction to what fossils are and how they're formed, collected, and identified. Next, the University of California Museum of Paleontology offers the Web site Learning From the Fossil Record (2), which contains several learning resources and lesson plans. Topics covered include Determining Age of Rocks and Fossils, Fossilization and Adaptation: Activities in Paleontology, and Microfossils. The third site is a US Geological Survey publication entitled Fossils, Rocks, and Time (3). Visitors can learn about succession, geologic time, and other relevant facts about how fossils are studied. The University of Arizona Department of Geosciences maintains the next site, which is entitled Petrified Wood (4). It provides information on Petrified Forest National Park, an interactive look at the process of petrification, and more. Offered by the Museum Victoria, the fifth site, Dating Rocks and Fossils (5), explains the difference between relative and absolute (radiometric) dating. It also includes a chart that gives the various isotopes used, their half-life, daughter isotope, and geologic application. The next site, provided by the BBC and their Walking With Dinosaurs series, is called Fossil Detectives (6). The site describes why dinosaur fossils are so rare, where the best place to find them is, how their age is estimated, and other interesting information that can be found on this page and the rest of the site. Next, from the Florida Museum of Natural History comes the Fossil Preparation and Conservation (7) Web site. A more in-depth and technical description of fossil preparation is presented, including the use of cosolidants, adhesives, and various tools. The last site is from the University of Kentucky Paleontological Society called Photographs of Fossils Found on KPS Fieldtrips (8). As you would expect, the site contains a large categorized list of fossils, each briefly described and linked to its respective photograph.

2002-01-01

36

Fossils  

NSDL National Science Digital Library

Paleontologists seldom have the good fortune to find a complete set of remains of an ancient organism that is wholly intact. For instance, the discovery of a frozen woolly mammoth carcass, preserved hair and all, was a truly rare event. More common are discoveries of incomplete remains, such as bones, teeth, or hair, and trace fossils, such as footprints or leaf impressions, which indicate an organism once existed even though its actual remains have not been found. This slide presentation reveals the variety of forms that fossils take, as well as examples of the kinds of life whose remains have been preserved. A background essay and discussion questions are included.

37

Hominin cognitive evolution: identifying patterns and processes in the fossil and archaeological record  

PubMed Central

As only limited insight into behaviour is available from the archaeological record, much of our understanding of historical changes in human cognition is restricted to identifying changes in brain size and architecture. Using both absolute and residual brain size estimates, we show that hominin brain evolution was likely to be the result of a mix of processes; punctuated changes at approximately 100 kya, 1 Mya and 1.8 Mya are supplemented by gradual within-lineage changes in Homo erectus and Homo sapiens sensu lato. While brain size increase in Homo in Africa is a gradual process, migration of hominins into Eurasia is associated with step changes at approximately 400 kya and approximately 100 kya. We then demonstrate that periods of rapid change in hominin brain size are not temporally associated with changes in environmental unpredictability or with long-term palaeoclimate trends. Thus, we argue that commonly used global sea level or Indian Ocean dust palaeoclimate records provide little evidence for either the variability selection or aridity hypotheses explaining changes in hominin brain size. Brain size change at approximately 100 kya is coincident with demographic change and the appearance of fully modern language. However, gaps remain in our understanding of the external pressures driving encephalization, which will only be filled by novel applications of the fossil, palaeoclimatic and archaeological records. PMID:22734056

Shultz, Susanne; Nelson, Emma; Dunbar, Robin I. M.

2012-01-01

38

The Homo floresiensis cranium (LB1): Size, scaling, and early Homo affinities  

PubMed Central

The skeletal remains of a diminutive small-brained hominin found in Late Pleistocene cave deposits on the island of Flores, Indonesia were assigned to a new species, Homo floresiensis [Brown P, et al. (2004) A new small-bodied hominin from the Late Pleistocene of Flores, Indonesia. Nature 431: 1055–1061]. A dramatically different interpretation is that this material belongs not to a novel hominin taxon but to a population of small-bodied modern humans affected, or unaffected, by microcephaly. The debate has primarily focused on the size and shape of the endocranial cavity of the type specimen, LB1, with less attention being paid to the morphological evidence provided by the rest of the LB1 cranium and postcranium, and no study thus far has addressed the problem of how scaling would affect shape comparisons between a diminutive cranium like LB1 and the much larger crania of modern humans. We show that whether or not the effects of its small cranial size are accounted for, the external cranial morphology of the LB1 cranium cannot be accommodated within a large global sample of normal modern human crania. Instead, the shape of LB1, which is shown by multivariate analysis to differ significantly from that of modern humans, is similar to that of Homo erectus sensu lato, and, to a lesser extent, Homo habilis. Our results are consistent with hypotheses that suggest the Liang Bua specimens represent a diminutive population closely related to either early H. erectus s. l. from East Africa and/or Dmanisi or to H. habilis. PMID:18356300

Gordon, Adam D.; Nevell, Lisa; Wood, Bernard

2008-01-01

39

Narmada Homo erectus – A possible ancestor of the modern Indian  

Microsoft Academic Search

Tracing continuity of evolving humans with the aid of their scanty skeletal remains is an intricate puzzle. In the specific case of Indian sub-continent, the so-far oldest human ancestor, the Narmada hominid, has wider spatial distance both from the antecedents on one side and the descendents on the other side. Ramapithecus, a geographically closely located primate earlier considered of hominidae

Arun Sonakia; Henry de Lumley

2006-01-01

40

Human migrations map, interactive 2D animationSite: DNA Interactive (www.dnai.org)  

NSDL National Science Digital Library

The red lines show the possible migration pathway of the ancient human Homo erectus (sometimes known as Homo ergaster). There is little controversy about the travels of H. erectus. This possible path was mapped using fossil evidence that spans more than 1.5 million years. Many researchers believe that H. erectus lived until approximately 300,000 years ago. However, H. erectus may have survived in Indonesia until 40,000 years ago.

2008-10-06

41

Variation in enamel thickness within the genus Homo Tanya M. Smith a,b,*, Anthony J. Olejniczak b  

E-print Network

Homo Archaic Homo Neanderthal a b s t r a c t Recent humans and their fossil relatives are classified, Neanderthals show relatively thin enamel in their incisors, canines, premolars, and molars, although incisor

Smith, Tanya M.

42

Influence d'Ustilago hypodytes (Schlecht.) Fr. sur le tallage et la montaison de Bromus erectus Huds.  

E-print Network

Influence d'Ustilago hypodytes (Schlecht.) Fr. sur le tallage et la montaison de Bromus erectus, Tallage, Bromus erectus Dans le but d'étudier l'action d'un charbon, Ustilago hypodytes (Schlecht.) Fr Parasitism, Smut, Ustilago hypodytes, Grasses, Tillering Bromus erectus Influence of Ustilago hypodytes

Paris-Sud XI, Université de

43

Stratigraphic, chronological and behavioural contexts of Pleistocene Homo sapiens from Middle Awash, Ethiopia  

Microsoft Academic Search

Clarifying the geographic, environmental and behavioural contexts in which the emergence of anatomically modern Homo sapiens occurred has proved difficult, particularly because Africa lacked adequate geochronological, palaeontological and archaeological evidence. The discovery of anatomically modern Homo sapiens fossils at Herto, Ethiopia, changes this. Here we report on stratigraphically associated Late Middle Pleistocene artefacts and fossils from fluvial and lake margin

J. Desmond Clark; Yonas Beyene; Giday WoldeGabriel; William K. Hart; Paul R. Renne; Henry Gilbert; Alban Defleur; Gen Suwa; Shigehiro Katoh; Kenneth R. Ludwig; Jean-Renaud Boisserie; Berhane Asfaw; Tim D. White

2003-01-01

44

Homo floresiensis: Microcephalic, pygmoid, Australopithecus, or Homo?  

Microsoft Academic Search

The remarkable partial adult skeleton (LB1) excavated from Liang Bua cave on the island of Flores, Indonesia, has been attributed to a new species, Homo floresiensis, based upon a unique mosaic of primitive and derived features compared to any other hominin. The announcement precipitated widespread interest, and attention quickly focused on its possible affinities. LB1 is a small-bodied hominin with

Debbie Argue; Denise Donlon; Colin Groves; Richard Wright

2006-01-01

45

Megadontia, striae periodicity and patterns of enamel secretion in Plio-Pleistocene fossil hominins  

PubMed Central

Early hominins formed large and thick-enamelled cheek-teeth within relatively short growth periods as compared with modern humans. To understand better the developmental basis of this process, we measured daily enamel increments, or cross striations, in 17 molars of Plio-Pleistocene hominins representing seven different species, including specimens attributed to early Homo. Our results show considerable variation across species, although all specimens conformed to the known pattern characterised by greater values in outer than inner enamel, and greater cuspal than cervical values. We then compared our results with the megadontia index, which represents tooth size in relation to body mass, for each species to assess the effect of daily growth rates on tooth size. Our results indicate that larger toothed (megadont) taxa display higher rates or faster forming enamel than smaller toothed hominins. By forming enamel quickly, large tooth crowns were able to develop within the constraints of shorter growth periods. Besides daily increments, many animals express long-period markings (striae of Retzius) in their enamel. We report periodicity values (number of cross striations between adjacent striae) in 14 new specimens of Australopithecus afarensis, Paranthropus aethiopicus, Paranthropus boisei, Homo habilis, Homo rudolfensis and Homo erectus, and show that long-period striae express a strong association with male and average male–female body mass. Our results for Plio-Pleistocene hominins show that the biological rhythms that give rise to long-period striae are encompassed within the range of variation known for modern humans, but show a lower mean and modal value of 7 days in australopithecines. In our sample of early Homo, mean and modal periodicity values were 8 days, and therefore similar to modern humans. These new data on daily rates of enamel formation and periodicity provide a better framework to interpret surface manifestations of internal growth markings on fossil hominin tooth crowns. Importantly, our data on early hominin cross striation variation may now contribute towards solving difficult taxonomic diagnoses where much may depend on fragmentary molar remains and enamel structure. PMID:19172730

Lacruz, Rodrigo S; Dean, M Christopher; Ramirez-Rozzi, Fernando; Bromage, Timothy G

2008-01-01

46

Hominid Fossil Record Geology 230: Fossils and Evolution  

E-print Network

Hominid Fossil Record Geology 230: Fossils and Evolution #12;#12;Human ancestors A · Ardipithecus: oldest definite bipedal ancestor, over 4 M.Y. old · Australopithecus: the gracile, a hobbit-size human from Flores Island, Indonesia, 18,000 BP Modern human #12;Homo sapiens (Cro

Kammer, Thomas

47

Week of Aug. 5, 2002 Vol. 3, No. 15 A D e p a r t m e n t o f E n e r g y / U n i v e r s i t y o f C a l i f o r n i a L a b o r a t o r y  

E-print Network

, baboons and hyenas; in fact, marks on the fossilized skull indicate that the Homo erectus specimen may have been gnawed on by hyenas or other animals after it died. The latest fossils are about a million

48

Craniometric variation in large-bodied hominoids: testing the single-species hypothesis for Homo habilis  

Microsoft Academic Search

The species question regarding Homo habilis remains unresolved. This study tests the null hypothesis that this hominid taxon represents a single paleospecies by comparing the fossils' magnitude and pattern of craniometric variation to samples of extant, large-bodied hominoids including Pan troglodytes, Gorilla gorilla, Pongo pygmaeus and Homo sapiens. Unlike previous quantitative approaches to this problem, randomization methodology is used to

Andrew Kramer; Steven M. Donnelly; James H. Kidder; Stephen D. Ousley; Stephen M. Olah

1995-01-01

49

App. 1. Internet supplement to: Zeiter, M. & Stampfli, A. 2008. Long-term assessment of seed provenance effect on the establishment of the perennial grass Bromus erectus  

E-print Network

provenance effect on the establishment of the perennial grass Bromus erectus Journal of Vegetation Science 19: 821-830; doi: 10.3170/2008-8-18455 App. 1. Performance of Bromus erectus from three provenances

Stampfli, Andreas

50

-Long-term assessment of seed provenance effect on the establishment of Bromus erectus -821 Journal of Vegetation Science 19: 821-830, 2008  

E-print Network

- Long-term assessment of seed provenance effect on the establishment of Bromus erectus - 821 of the perennial grass Bromus erectus Zeiter, Michaela1* & Stampfli, Andreas1,2 1Institute of Plant Sciences Switzerland. Methods: 18 000 seeds of Bromus erectus of three provenances were sown in a reciprocal design

Stampfli, Andreas

51

Geometric properties and comparative biomechanics of Homo floresiensis mandibles.  

PubMed

The hypodigm of Homo floresiensis from the cave of Liang Bua on Flores Island in the archipelago of Indonesia includes two mandibles (LB1/2 and LB6/1). The morphology of their symphyses and corpora has been described as sharing similarities with both australopiths and early Homo despite their Late Pleistocene age. Although detailed morphological comparisons of these mandibles with those of modern and fossil hominin taxa have been made, a functional analysis in the context of masticatory biomechanics has yet to be performed. Utilizing data on cortical bone geometry from computed tomography scans, we compare the mechanical attributes of the LB1 and LB6 mandibles with samples of modern Homo, Pan, Pongo, and Gorilla, as well as fossil samples of Paranthropus robustus, Australopithecus africanus and South African early Homo. Structural stiffness measures were derived from the geometric data to provide relative measures of mandibular corpus strength under hypothesized masticatory loading regimes. These mechanical variables were evaluated relative to bone area, mandibular length and estimates of body size to assess their functional affinities and to test the hypothesis that the Liang Bua mandibles can be described as scaled-down variants of either early hominins or modern humans. Relative to modern hominoids, the H. floresiensis material appears to be relatively strong in terms of rigidity in torsion and transverse bending, but is relatively weak under parasagittal bending. Thus, they are 'robust' relative to modern humans (and comparable with australopiths) under some loads but not others. Neither LB1 nor LB6 can be described simply as 'miniaturized' versions of modern human jaws since mandible length is more or less equivalent in Homo sapiens and H. floresiensis. The mechanical attributes of the Liang Bua mandibles are consistent with previous inferences that masticatory loads were reduced relative to australopiths but remained elevated relative to modern Homo. PMID:24560803

Daegling, David J; Patel, Biren A; Jungers, William L

2014-03-01

52

Additional Evidence for Morpho-Dimensional Tooth Crown Variation in a New Indonesian H. erectus Sample from the Sangiran Dome (Central Java)  

PubMed Central

This contribution reports fifteen human fossil dental remains found during the last two decades in the Sangiran Dome area, in Central Java, Indonesia. Among this sample, only one of the specimens had already been briefly described, with the other fourteen remaining unreported. Seven of the fifteen isolated teeth were found in a secured stratigraphic context in the late Lower-early Middle Pleistocene Kabuh Formation. The remaining elements were surface finds which, based on coincidental sources of information, were inferred as coming from the Kabuh Formation. Mainly constituted of permanent molars, but also including one upper incisor and one upper premolar, this dental sample brings additional evidence for a marked degree of size variation and time-related structural reduction in Javanese H. erectus. This is notably expressed by a significant decrease of the mesiodistal diameter, frequently associated to the reduction or even loss of the lower molar distal cusp (hypoconulid) and to a more square occlusal outline. In addition to the hypoconulid reduction or loss, this new sample also exhibits a low frequency of the occlusal Y-groove pattern, with a dominance of the X and, to a lesser extent, of the+patterns. This combination is rare in the Lower and early Middle Pleistocene paleoanthropological record, including in the early Javanese dental assemblage from the Sangiran Dome. On the other hand, similar dental features are found in Chinese H. erectus and in H. heidelbergensis. As a whole, this new record confirms the complex nature of the intermittent exchanges that occurred between continental and insular Southeast Asia through the Pleistocene. PMID:23843996

Zanolli, Clément

2013-01-01

53

Fossil Fondue  

NSDL National Science Digital Library

To understand how fossils are formed, students model the process of fossilization by making fossils using small toy figures and melted chocolate. They extend their knowledge to the many ways that engineers aid in the study of fossils, including the development of tools and technologies for determining the physical and chemical properties of fossilized organisms, and how those properties tell a story of our changing world.

Integrated Teaching And Learning Program

54

4th Grade Fossils  

NSDL National Science Digital Library

Introduction to Fossils What is a fossil What is a Fossil? Body and Trace Fossils Body and Trace Fossils Life of a Vertebrate fossil Life of a Vertebrate Fossil Finding Fossils Finding Fossils How fossils are found How fossils are formed Age of Fossils Age of Fossils in Sedimentary Rock Fossils found in Utah Fossils found in Utah Where fossils are found in Utah Where fossils are found in Utah Utah County Map Utah County Map ...

richrigby

2010-01-26

55

Fossil primates 1 Fossil primates  

E-print Network

Fossil primates 1 Fossil primates Extinct members of the order of mammals to which humans belong group of living primates. However, the chewing teeth and the locomotor anatomy of these fossil forms). These animals are also known from fossil deposits on Ellesmere Island, in Arctic Canada, which was then covered

Delson, Eric

56

Discovering Fossils: Fossil Tools & Resources  

NSDL National Science Digital Library

Fossil enthusiasts Roy Shephard and Luci Algar combined their professional skills in media and education to develop this informative and entertaining website. Designed to be educational and accessible to children, this site presents a wide variety of information about fossils. The site contains a nice collection of images and diagrams; and includes a fossils guide for beginners, information on preparing fossils, a collection of fossil myths, information on ammonites, and more. The site also contains a Games & Activities section for teachers and students, a glossary of fossil terms, a neat diagram depicting the evolution of life on our planet, and even some free fossil desktop images.

57

The dispersal of Homo sapiens across southern Asia: how early, how often, how complex?  

NASA Astrophysics Data System (ADS)

The timing and the paths of colonization of southern Asia by Homo sapiens are poorly known, though many population geneticists, paleoanthropologists, and archaeologists have contended that this process began with dispersal from East Africa, and occurred between 60,000 and 40,000 years ago. However, the evidence for this scenario is very weak, particularly the lack of human skeletal evidence between the Levant and Borneo before 40 ka, and other explanations are possible. Here we argue that environmental and archaeological information is increasingly indicating the likelihood that H. sapiens exited Africa much earlier than commonly thought, and may have colonized much of southern Asia well before 60,000 years ago. Additionally, we cannot exclude the possibility that several dispersal events occurred, from both North and East Africa, nor the likelihood that early populations of H. sapiens in southern Asia interbred with indigenous populations of Neanderthals, Denisovans and Homo erectus. The population history of southern Asia during the Upper Pleistocene is likely far more complex than currently envisaged.

Dennell, Robin; Petraglia, Michael D.

2012-07-01

58

"Fossil" Forecasting.  

ERIC Educational Resources Information Center

Presents a density study in which students calculate the density of limestone substrate to determine if the specimen contains any fossils. Explains how to make fossils and addresses national standards. (YDS)

Brody, Michael J.; deOnis, Ann

2001-01-01

59

The Emergence of Homo sapiens.  

ERIC Educational Resources Information Center

Describes chronologically the evolution of the human race on earth so as to refute Darwin's theory of descent from animals. Skull fragments from sites around the world suggest at least two possible routes toward the emergence of Homo sapiens sapiens. (Author/SK)

Rensberger, Boyce

1980-01-01

60

Finding Fossils  

NSDL National Science Digital Library

This OLogy activity serves as a kid-friendly how-to manual about searching for fossils. In Not Just Any Rock Will Do, kids learn that fossils "hide out" in sedimentary rock and see examples of shale and sandstone. Do's and Don'ts for Fossil Hunters gives kids practical tips and a list of fossil-hunting supplies. In Fossils You May Find, there are photos of common invertebrate, vertebrate, and plant fossils to guide kids. Paleontology Clubs and Web Sites lists resources to help kids determine where to hunt for fossils. In Keeping a Field Journal, kids are shown a sample journal entry that points out the types of information they should record.

61

Fossils 1: Fossils and Dinosaurs  

NSDL National Science Digital Library

This lesson will go beyond naming dinosaurs and give students a broad understanding of how we know about the great beasts. This lesson focuses on what we have learned and can learn from fossils. The follow-up lesson, Dinosaurs Fossils - Uncovering the Facts, explores what information can be discerned by comparing fossils to living organisms.

Science Netlinks

2001-10-20

62

Fossil Excavation  

NSDL National Science Digital Library

In this activity students excavate their own fossil from a teacher-prepared "rock biscuit". Students chip away the matrix with wooden stirring rods (or sharpened wooden dowels) and glue brushes. In each biscuit is a genuine fossil such as a shark's tooth. The activity is designed to be the culmination of a lesson about fossil collecting, the importance of recording data, and different preparation methods.

63

Fossil formation  

NSDL National Science Digital Library

The National Science Education Standards Life Science Content Standard mentions that fossils indicate extinct species and contribute to an understanding of evolution and diversity. The Earth and Space Sciences Content Standard tells us they provide clues about past environments. But what is a fossil? How does it form? The processes can be complex. An understanding of fossil formation will enable accurate student conceptions of related science concepts including methods of science in geology, paleontology, and evolution.

University, Staff A.

2008-03-07

64

Does seed dispersal by sheep affect the population genetic structure of the calcareous grassland species Bromus erectus?  

Microsoft Academic Search

This study investigates the contribution of the traditional land-use system “sheep herding” (transhumance) to the gene flow among populations. Three sheep trails with altogether 12 calcareous grassland sites were chosen for the analysis of the tussock grass Bromus erectus, which is known to be the species with the highest rate of dispersal via sheep fleece. Each trail links two to

Christian Willerding; Peter Poschlod

2002-01-01

65

Fossil Fuels.  

ERIC Educational Resources Information Center

This instructional unit is one of 10 developed by students on various energy-related areas that deals specifically with fossil fuels. Some topics covered are historic facts, development of fuels, history of oil production, current and future trends of the oil industry, refining fossil fuels, and environmental problems. Material in each unit may…

Crank, Ron

66

Ediacara Fossils  

ERIC Educational Resources Information Center

Now, a research team from Virginia Tech and Nanjing Institute of Geology and Paleontology has discovered uniquely well-preserved fossil forms from 550-million-year-old rocks of the Ediacaran Period. The research appears in the Proceedings of the National Academy of Sciences. The discovery of these unusually preserved fossils reveals unprecedented…

Science Teacher, 2005

2005-01-01

67

Fossil spiders.  

PubMed

Over the last three decades, the fossil record of spiders has increased from being previously biased towards Tertiary ambers and a few dubious earlier records, to one which reveals a much greater diversity in the Mesozoic, with many of the modern families present in that era, and with clearer evidence of the evolutionary history of the group. We here record the history of palaeoarachnology and the major breakthroughs which form the basis of studies on fossil spiders. Understanding the preservation and taphonomic history of spider fossils is crucial to interpretation of fossil spider morphology. We also review the more recent descriptions of fossil spiders and the effect these discoveries have had on the phylogenetic tree of spiders. We discuss some features of the evolutionary history of spiders and present ideas for future work. PMID:19961468

Selden, Paul A; Penney, David

2010-02-01

68

Fossil Fuels  

NSDL National Science Digital Library

How much does the United States depend on fossil fuels? This web page, part of a site on the future of energy, introduces students to fossil fuels as an energy source. Here students read about the uses, benefits, and limitations of fossil fuels. There is also information on how these fuels are distributed geographically and how they affect the U.S. economy through supply and demand. Thought-provoking questions afford students opportunities to reflect on what they've read. Articles about clean coal, the national energy policy, and the formation of fossil fuels, together with a fossil fuels fact sheet, are accessible from a sidebar. In addition, five PBS NewsHour links to energy-related stories are included.

Iowa Public Television. Explore More Project

2004-01-01

69

Fossil Halls  

NSDL National Science Digital Library

The American Museum of Natural History is home to the world's largest collection of vertebrate fossils, totaling nearly one million specimens. This Web site offers visitors a virtual visit to the Museum's famed Fossil Halls. It features sections on Cladistics, Vertebrate Evolution, Exhibit Specimens, a collection of 19 biographies of important people in paleontology and Virtual Tours of four of the halls. There is also an elementary school teacher guide to the museum exhibit.

70

Elastic energy storage in the shoulder and the evolution of high-speed throwing in Homo  

PubMed Central

Although some primates, including chimpanzees, throw objects occasionally1,2, only humans regularly throw projectiles with high speed and great accuracy. Darwin noted that humans’ unique throwing abilities, made possible when bipedalism emancipated the arms, enabled foragers to effectively hunt using projectiles3. However, there has been little consideration of the evolution of throwing in the years since Darwin made his observations, in part because of a lack of evidence on when, how, and why hominins evolved the ability to generate high-speed throws4-8. Here, we show using experimental studies of throwers that human throwing capabilities largely result from several derived anatomical features that enable elastic energy storage and release at the shoulder. These features first appear together approximately two million years ago in the species Homo erectus. Given archaeological evidence that suggests hunting activity intensified around this time9, we conclude that selection for throwing in order to hunt likely played an important role in the evolution of the human genus. PMID:23803849

Roach, Neil T.; Venkadesan, Madhusudhan; Rainbow, Michael J.; Lieberman, Daniel E.

2013-01-01

71

Size, shape, and asymmetry in fossil hominins: The status of the LB1 cranium based on 3D morphometric analyses  

E-print Network

Size, shape, and asymmetry in fossil hominins: The status of the LB1 cranium based on 3D that LB1 best fits predictions for a small specimen of fossil Homo but not for a small modern human extant African ape species. Compared to other fossil specimens, the degree of asymmetry in LB1

Baab, Karen L.

72

Bird Fossils  

NSDL National Science Digital Library

A fossil of a small, feathered animal, Longisquama insignis, that lived approximately 220 million years ago (Ma) in what is now Central Asia, was re-discovered recently in the dusty drawers of a Moscow museum collection. This discovery has rocked the paleontological world because the fossil exhibits feather impressions, making it possibly the world's oldest known bird. Archaeopteryx, thought until now to be the oldest true bird, is from a limestone deposit in Germany dated at approximately 145 Ma. This new fossil discovery fires the debate over whether birds are descended from dinosaurs, or branched off from an earlier group of reptiles. This week's In The News takes a look at scientists' latest understanding of the reptile-bird evolutionary transition, and the surrounding controversies.

73

The Origin of Homo sapiens in the Light of Different Research Methods  

Microsoft Academic Search

The origins of Homo sapiens is a central issue of modern paleoanthropology. The available fossil material serves as a basis for postulating different\\u000a hypotheses and models, but as is widely appreciated, anthropologists have yet to reach a consensus about human origins. It\\u000a seems possible that the main reasons behind such an irreducible divergence of opinions are different methodological approaches\\u000a rather

Jacek Tomczyk

2006-01-01

74

Inventing Homo gardarensis: prestige, pressure, and human evolution in interwar Scandinavia.  

PubMed

In the 1920s there were still very few fossil human remains to support an evolutionary explanation of human origins. Nonetheless, evolution as an explanatory framework was widely accepted. This led to a search for ancestors in several continents with fierce international competition. With so little fossil evidence available and the idea of a Missing Link as a crucial piece of evidence in human evolution still intact, many actors participated in the scientific race to identify the human ancestor. The curious case of Homo gardarensis serves as an example of how personal ambitions and national pride were deeply interconnected as scientific concerns were sometimes slighted in interwar palaeoanthropology. PMID:24941795

Kjaergaard, Peter C

2014-06-01

75

The Homo Energeticus: maturity, inheritance, identity  

NASA Astrophysics Data System (ADS)

In this letter, modern society’s intimate bond to the convenience and reliability of delivered energy services results in a form of identification I call the Homo Energeticus. The Homo Energeticus relies upon a mature system of services for achieving an equivalency of status and prestige that is historically similar to the morality of a noble class. I describe the uniqueness of this identity by its imperative for acquiring experience through an invisibility of energy expenditures. In this way, the Homo Energeticus cultivates a highly individualized life whose ambience of perfection, while created personally, is only successful insofar as it conceals energy expenditures in labor and supply.

Mason, Arthur

2013-03-01

76

Genetic and Fossil Evidence for the Origin of Modern Humans  

Microsoft Academic Search

The origin of living Homo sapiens has once again been the subject of much debate. Genetic data on present human population relationships and data from the Pleistocene fossil hominid record are used to compare two contrasting models for the origin of modern humans. Both genetics and paleontology support a recent African origin for modern humans rather than a long period

C. B. Stringer; P. Andrews

1988-01-01

77

Fossil Fuels  

NSDL National Science Digital Library

The Department of Energy Web site Fossil Fuels is billed as an energy education site mainly for older kids, but can be enjoyed by adult kids as well. The site gives an introduction to energy, and then a more detailed look at the acquisition and uses of coal, oil, and gas. The good descriptions, illustrations, and animations, along with the frequent questions page and glossary of related terms, combine to give a clear and enlightening overview of the subject.

78

Photophysical properties of?-homo-tyrosine derivatives.  

PubMed

The observed monoexponential fluorescence decay of N-acetyl-?-homo-tyrosine methylamide (Ac-?Hty-NHMe) (I) and N-acetyl-(O-methyl)-?-homo-tyrosine methylamide (Ac-?Hty(OMe)-NHMe) (II) is supporting the rotamer population theory, according to which rotamers are responsible for heterogeneity of the fluorescence decay of N-acetyl-tyrosine amide or tyrosine incorporated within a peptide chain, in general. PMID:24178481

Lankiewicz, L; Lanoszka, J; O?dziej, S; Wiczk, W

1996-06-01

79

The evolutionary history of the hominin hand since the last common ancestor of Pan and Homo  

PubMed Central

Molecular evidence indicates that the last common ancestor of the genus Pan and the hominin clade existed between 8 and 4 million years ago (Ma). The current fossil record indicates the Pan-Homo last common ancestor existed at least 5 Ma and most likely between 6 and 7 Ma. Together, the molecular and fossil evidence has important consequences for interpreting the evolutionary history of the hand within the tribe Hominini (hominins). Firstly, parsimony supports the hypothesis that the hand of the last common ancestor most likely resembled that of an extant great ape overall (Pan, Gorilla, and Pongo), and that of an African ape in particular. Second, it provides a context for interpreting the derived changes to the hand that have evolved in various hominins. For example, the Australopithecus afarensis hand is likely derived in comparison with that of the Pan–Homo last common ancestor in having shorter fingers relative to thumb length and more proximo-distally oriented joints between its capitate, second metacarpal, and trapezium. This evidence suggests that these derived features evolved prior to the intensification of stone tool-related hominin behaviors beginning around 2.5 Ma. However, a majority of primitive features most likely present in the Pan-Homo last common ancestor are retained in the hands of Australopithecus, Paranthropus/early Homo, and Homo floresiensis. This evidence suggests that further derived changes to the hands of other hominins such as modern humans and Neandertals did not evolve until after 2.5 Ma and possibly even later than 1.5 Ma, which is currently the earliest evidence of Acheulian technology. The derived hands of modern humans and Neandertals may indicate a morphological commitment to tool-related manipulative behaviors beyond that observed in other hominins, including those (e.g. H. floresiensis) which may be descended from earlier tool-making species. PMID:18380869

Tocheri, Matthew W; Orr, Caley M; Jacofsky, Marc C; Marzke, Mary W

2008-01-01

80

Describing Fossils  

NSDL National Science Digital Library

Students are given a description of a fossil brachiopod, from the literature, along with a one-page handout describing the basic morphology of brachiopods. Students work independently to make a scale drawing of the fossil described (brachial valve, pedicle valve, anterior view, lateral view). They have access to textbooks (Moore, Laliker & Fisher; Clarkson), the Treatise volume, and the internet to get information on morphological terms. This takes about an hour, after which I display all of the diagrams on the wall along with the photographs from the paper from which the description was extracted. We discuss some of the differences and where problems arose in interpreting the description. I emphasize the importance of an accurate drawing or photograph to accompany a description. Students are then given a different brachiopod specimen and asked to produce a written description (pedicle-valve, brachial valve, anterior view, lateral view) of their fossil similar to the one that they readâi.e. using all of the appropriate terms. They are told that other students will be trying to match their description to their specimen. I collect all of the descriptions, edit them (remove portions that use incorrect terminology or inappropriate), and produce a handout of all of the descriptions. At the next class, students are given the descriptions and asked to match descriptions to specimens. They do this independently outside of class. The specimens are made available in the lab room for several days. I add a couple of 'extra' specimens (without description) so that it is not a process of elimination.

Judy Massare

81

Radiometric dating of the type-site for Homo heidelbergensis at Mauer, Germany  

PubMed Central

The Mauer mandible, holotype of Homo heidelbergensis, was found in 1907 in fluvial sands deposited by the Neckar River 10 km southeast of Heidelberg, Germany. The fossil is an important key to understanding early human occupation of Europe north of the Alps. Given the associated mammal fauna and the geological context, the find layer has been placed in the early Middle Pleistocene, but confirmatory chronometric evidence has hitherto been missing. Here we show that two independent techniques, the combined electron spin resonance/U-series method used with mammal teeth and infrared radiofluorescence applied to sand grains, date the type-site of Homo heidelbergensis at Mauer to 609 ± 40 ka. This result demonstrates that the mandible is the oldest hominin fossil reported to date from central and northern Europe and raises questions concerning the phyletic relationship of Homo heidelbergensis to more ancient populations documented from southern Europe and in Africa. We address the paleoanthropological significance of the Mauer jaw in light of this dating evidence. PMID:21041630

Wagner, Günther A.; Krbetschek, Matthias; Degering, Detlev; Bahain, Jean-Jacques; Shao, Qingfeng; Falguères, Christophe; Voinchet, Pierre; Dolo, Jean-Michel; Garcia, Tristan; Rightmire, G. Philip

2010-01-01

82

Are the oldest 'fossils', fossils  

NASA Technical Reports Server (NTRS)

A comparative statistical study has been carried out on populations of modern algae, Precambrian algal microfossils, the 'organized elements' of the Orgueil carbonaceous meteorite, and the oldest microfossil-like objects now known (spheroidal bodies from the Fig Tree and Onverwacht Groups of the Swaziland Supergroup, South Africa). The distribution patterns exhibited by the more than 3000 m.y.-old Swaziland microstructures bear considerable resemblance to those of the abiotic 'organized elements' but differ rather markedly from those exhibited by younger, assuredly biogenic, populations. Based on these comparisons, it is concluded that the Swaziland spheroids could be, at least in part, of nonbiologic origin; these oldest known fossil-like microstructures should not be regarded as constituting firm evidence of Archean life.

Schopf, J. W.

1976-01-01

83

Plant phenology and soil fertility effects on below-ground carbon allocation for an annual ( Bromus madritensis) and a perennial ( Bromus erectus) grass species  

Microsoft Academic Search

Plant strategies for using available resources were explored through a comparative analysis of C allocation and use in the rhizosphere. The seasonal dynamics of plant C partitioning was compared for annual and perennial species of bromegrass (Bromus madritensis and B. erectus) in soils of different fertility using successive 2-week labelling with 14CO2. Measurements of labelled soil CO2 indicated that current

F. R Warembourg; H. D Estelrich

2001-01-01

84

Fossil energy review  

SciTech Connect

The Fossil Energy Review provides an update of key events in the Department of Energy's Fossil Energy Program. This issue contains topics relating to: clean coal technology; fossil energy research; and petroleum reserves. (JEF)

Not Available

1989-01-01

85

Will My Fossil Float?  

ERIC Educational Resources Information Center

Explains how young students can be introduced to fossils. Suggests books to read and science activities including "Fossils to Eat" where students make fossils from peanut butter, honey, and powdered milk. (PR)

Riesser, Sharon; Airey, Linda

1993-01-01

86

Body proportions of Homo habilis reviewed  

Microsoft Academic Search

The ratio of fore- to hindlimb size plays an important role in our understanding of human evolution. Although Homo habilis was relatively modern craniodentally, its body proportions are commonly believed to have been more apelike than in the earlier Australopithecus afarensis. The evidence for this, however, rests, on two fragmentary skeletons, OH 62 and KNM-ER 3735. The upper limb of

Martin Haeusler; Henry M McHenry

2004-01-01

87

Yawn Contagion and Empathy in Homo sapiens  

Microsoft Academic Search

The ability to share others' emotions, or empathy, is crucial for complex social interactions. Clinical, psychological, and neurobiological clues suggest a link between yawn contagion and empathy in humans (Homo sapiens). However, no behavioral evidence has been provided so far. We tested the effect of different variables (e.g., country of origin, sex, yawn characteristics) on yawn contagion by running mixed

Ivan Norscia; Elisabetta Palagi

2011-01-01

88

A description of the geological context, discrete traits, and linear morphometrics of the Middle Pleistocene hominin from Dali, Shaanxi Province, China.  

PubMed

In 1978, a nearly complete hominin fossil cranium was recovered from loess deposits at the site of Dali in Shaanxi Province, northwestern China. It was subsequently briefly described in both English and Chinese publications. Here we present a comprehensive univariate and nonmetric description of the specimen and provide comparisons with key Middle Pleistocene Homo erectus and non-erectus hominins from Eurasia and Africa. In both respects we find affinities with Chinese H. erectus as well as African and European Middle Pleistocene hominins typically referred to as Homo heidelbergensis. Specifically, the Dali specimen possesses a low cranial height, relatively short and arched parietal bones, an angled occipital bone, and a nonprominent articular tubercle relative to the preglenoid surface all of which distinguish it from Afro/European Middle Pleistocene Homo and align it with Asian H. erectus. At the same time, it displays a more derived morphology of the supraorbital torus and supratoral sulcus and a thinner tympanic plate than H. erectus, a relatively long upper (lambda-inion) occipital plane with a clear separation of inion and opisthocranion, and an absolute and relative increase in brain size, all of which align it with African and European Middle Pleistocene Homo. Finally, traits such as the form of the frontal keel and the relatively short, broad midface align Dali specifically with other Chinese specimens from the Middle Pleistocene and Late Pleistocene, including H. erectus, and differentiate these from the Afro/European specimens of this time period. PMID:23283667

Wu, Xinzhi; Athreya, Sheela

2013-01-01

89

Deductions from Fossil Preservtion  

NSDL National Science Digital Library

Students will view fossils, sometimes with supporting illustrations, and answer questions about them via deductive reasoning. The exercise is highly interactive, with the instructor providing hints and helpful questions. The questions concern ways in which fossil preservation reveals information about things like what kind of organism the fossil represents, how that organism lived, and how the fossil came into being.

Steven Stanley

90

EARLY DISPERSALS OF HOMO FROM AFRICA  

Microsoft Academic Search

! Abstract The worldwide distribution of our species, Homo sapiens, has its roots in the early Pleistocene epoch. However, evidence has been sufficient only in the past decade,to overcome,the conventional wisdom,that hominins,had been restricted to Africa until about 800,000 years ago. Indeed, the idea that hominin dispersal was technologicallymediated,andthusmustcorrelatewithchangesinstonetooltechnology seen at the Olduwan\\/Acheulean transition, has proven to be a persuasive

Susan C. Anton; Carl C. Swisher; III

2004-01-01

91

The hominin fossil record: taxa, grades and clades  

PubMed Central

This paper begins by reviewing the fossil evidence for human evolution. It presents summaries of each of the taxa recognized in a relatively speciose hominin taxonomy. These taxa are grouped in grades, namely possible and probable hominins, archaic hominins, megadont archaic hominins, transitional hominins, pre-modern Homo and anatomically modern Homo. The second part of this contribution considers some of the controversies that surround hominin taxonomy and systematics. The first is the vexed question of how you tell an early hominin from an early panin, or from taxa belonging to an extinct clade closely related to the Pan-Homo clade. Secondly, we consider how many species should be recognized within the hominin fossil record, and review the philosophies and methods used to identify taxa within the hominin fossil record. Thirdly, we examine how relationships within the hominin clade are investigated, including descriptions of the methods used to break down an integrated structure into tractable analytical units, and then how cladograms are generated and compared. We then review the internal structure of the hominin clade, including the problem of how many subclades should be recognized within the hominin clade, and we examine the reliability of hominin cladistic hypotheses. The last part of the paper reviews the concepts of a genus, including the criteria that should be used for recognizing genera within the hominin clade. PMID:18380861

Wood, Bernard; Lonergan, Nicholas

2008-01-01

92

Encephalization and allometric trajectories in the genus Homo: Evidence from the Neandertal and modern lineages  

PubMed Central

The term “encephalization” is commonly used to describe an enlargement in brain size, considered as either absolute endocranial volumes or relative values in relation to body size. It is widely recognized that a considerable endocranial expansion occurred throughout the evolution of the genus Homo. This article aims to evaluate whether this phenomenon was the outcome of distinct evolutionary lineages, reaching similar brain expansions but through different trajectories. Endocranial morphology was studied in a sample of fossil hominines by multivariate approaches using both traditional metrics and geometric morphometrics. The analysis was focused on the transition from a generalized archaic pattern within the genus Homo to the modern morphology and compared with changes that occurred along the Neandertal lineage. The main result was the identification of two different evolutionary trajectories, in which a similar expansion in endocranial size has been reached by different changes in shape. Along the Neandertal lineage we observed maintenance of an “archaic” endocranial model, in which a large amount of variability is based on a single allometric trend. By contrast, when modern endocasts were compared with nonmodern ones, we found important differences apparently led by a parietal expansion. In this light, the origin of our species may have represented the opportunity to surpass the constraints imposed on encephalization by the ontogenetic pattern shared by nonmodern Homo representatives. PMID:14673084

Bruner, Emiliano; Manzi, Giorgio; Arsuaga, Juan Luis

2003-01-01

93

Leukotriene signaling in the extinct human subspecies Homo denisovan and Homo neanderthalensis. Structural and functional comparison with Homo sapiens.  

PubMed

Mammalian lipoxygenases (LOXs) have been implicated in cell differentiation and in the biosynthesis of pro- and anti-inflammatory lipid mediators. The initial draft sequence of the Homo neanderthalensis genome (coverage of 1.3-fold) suggested defective leukotriene signaling in this archaic human subspecies since expression of essential proteins appeared to be corrupted. Meanwhile high quality genomic sequence data became available for two extinct human subspecies (H. neanderthalensis, Homo denisovan) and completion of the human 1000 genome project provided a comprehensive database characterizing the genetic variability of the human genome. For this study we extracted the nucleotide sequences of selected eicosanoid relevant genes (ALOX5, ALOX15, ALOX12, ALOX15B, ALOX12B, ALOXE3, COX1, COX2, LTA4H, LTC4S, ALOX5AP, CYSLTR1, CYSLTR2, BLTR1, BLTR2) from the corresponding databases. Comparison of the deduced amino acid sequences in connection with site-directed mutagenesis studies and structural modeling suggested that the major enzymes and receptors of leukotriene signaling as well as the two cyclooxygenase isoforms were fully functional in these two extinct human subspecies. PMID:25447821

Adel, Susan; Kakularam, Kumar Reddy; Horn, Thomas; Reddanna, Pallu; Kuhn, Hartmut; Heydeck, Dagmar

2015-01-01

94

Pliocene and Pleistocene Hominid-Bearing Sites from West of Lake Turkana, Kenya  

Microsoft Academic Search

Pliocene and Pleistocene fossil localities near the western shoreline of Lake Turkana, ranging in age between 1 million and 3.5 million years in age, have produced important new hominid specimens including most of a Homo erectus skeleton and a relatively complete early robust australopithecine cranium. The lacustrine, fluviatile, and terrestrial strata are designated the Nachukui Formation, which is subdivided into

J. M. Harris; F. H. Brown; M. G. Leakey; A. C. Walker; R. E. Leakey

1988-01-01

95

Transitional Tetrapod Fossil  

NSDL National Science Digital Library

In this video segment from NOVA: Judgment Day: Intelligent Design on Trial, learn about the discovery of a well-preserved transitional fossil and how such transitional fossils support the theory of evolution.

Foundation, Wgbh E.

2007-11-01

96

A new hominid fossil skull (L.H. 18) from the Ngaloba Beds, Laetoli, northern Tanzania  

Microsoft Academic Search

In 1976, a fossil hominid skull was recovered from the Ngaloba Beds at Laetoli, Northern Tanzania; its morphology is discussed here. The discovery of this skull is of great interest and importance because of its very substantial presumed antiquity and its largely anatomically modern morphology. The discovery has considerable implications for the antiquity and origin of modern Homo sapiens, a

M. H. Day; M. D. Leakey; C. Magori

1980-01-01

97

Follow a Fossil  

NSDL National Science Digital Library

The Follow a Fossil Web site is presented by the Denver Museum of Nature and Science. It documents the prospecting, evacuation, preparation, curation, research, and exhibiting of vertebrate, invertebrate, and plant fossils. The site is simple and effective, giving a good introduction to the process of finding and using fossils for learning about the past.

2000-01-01

98

Fossilized bioelectric wire - the trace fossil Trichichnus  

NASA Astrophysics Data System (ADS)

The trace fossil Trichichnus is proposed as an indicator of fossil bioelectric bacterial activity at the interface oxic - anoxic zone of marine sediments. This fulfils the idea that such processes, commonly found in the modern realm, should be also present in the geological past. Trichichnus is an exceptional trace fossil due to its very thin diameter (mostly less than 1 mm) and common pyritic filling. It is ubiquitous in some fine-grained sediments, where it has been interpreted as a burrow formed deeper than any other trace fossils, below the redox boundary. Trichichnus formerly referred to as deeply burrowed invertebrates, has been found as remnant of a fossilized intrasediment bacterial mat that is pyritized. As visualized in 3-D by means of X-ray computed microtomography scanner, Trichichnus forms dense filamentous fabric, which reflects that produced by modern large, mat-forming, sulphide-oxidizing bacteria, belonging mostly to Trichichnus-related taxa, which are able to house a complex bacterial consortium. Several stages of Trichichnus formation, including filamentous, bacterial mat and its pyritization, are proposed to explain an electron exchange between oxic and suboxic/anoxic layers in the sediment. Therefore, Trichichnus can be considered a fossilized "electric wire".

K?dzierski, M.; Uchman, A.; Sawlowicz, Z.; Briguglio, A.

2014-12-01

99

Mixed inoculation alters infection success of strains of the endophyte Epichloë bromicola on its grass host Bromus erectus.  

PubMed Central

Within-host competition in multiply infected hosts is considered an important component of host-parasite interactions, but experimental studies on the dynamics of multiple infections are still rare. We measured the infection frequencies of four strains of the fungal endophyte Epichloë bromicola on two genotypes of its host plant Bromus erectus after single- and double-strain inoculation. Double-strain inoculations resulted in fewer double, but more single, infections than expected on the basis of infection frequencies in single-strain inoculations. In most cases, only one of the two strains established an infection, and strains differed in their overall competitive ability. This pattern resembles the mutual exclusion scenarios in some theoretical models of parasite evolution. In addition, competitive ability varied with host genotype, which may represent a mechanism for the coexistence of strains in a population. Hence, considering the genetic variation in both host and parasite may be important for a better understanding of within-host dynamics and their role in epidemiology or (co)evolution. PMID:11886628

Wille, Patrick; Boller, Thomas; Kaltz, Oliver

2002-01-01

100

Fossil Mapping of Utah  

NSDL National Science Digital Library

Fossils are evidence of living organisms from the past and are usually preserved in sedimentary rocks. A fossil may be an impression left in sediments, the preserved remains of an organism, or a trace mark showing that an organism once existed. Fossils are usually made from the hard parts of an organism because soft parts decay quickly. Fossils provide clues to Earth's history. They provide evidence that can be used to make inferences about past environments. Fossils can be compared to one another, to living organisms, and to organisms that lived long ago. Students will understand how fossils are formed, where they may be found in Utah, and how they can be used to make inferences. Research locations where fossils are found in Utah and construct a simple fossil map. 4th Grade Utah Core Curriculum, Science Benchmark, Standard 4, Objective 1, UEN TASK Congratulations. You have all become Paleontologists. You study fossils and it is your job to map the fossils of Utah for the State. Students will be divided into 4 groups. Each group will be given a Utah County Map. Each group will focus on one category ...

Ramsey

2009-11-18

101

Postcrania and the specific mate recognition system  

Microsoft Academic Search

The Recognition Concept of Species is examined for its potential usefulness in discriminating speciation events in the hominid\\u000a fossil record. Controversies over species-specific characteristics amongHomo erectus and archaicHomo sapiens have centred on traits of the skull, largely because this element is most commonly preserved. Modern humans have an intuitive\\u000a knowledge of their own Specific Mate Recognition System (SMRS), and therefore

B. M. F. Galdikas; J. B. Duffy; H. Odwak; C. M. Purss; P. Vasey

1993-01-01

102

HOMO: A novel script for data mining of microarrays  

PubMed Central

HOMO.pl is a perl script that allows extracting important registers from an extensive data table or microarrays results. It is very useful in data mining for microarrays analysis. HOMO works as a homogenizer that converts the initial data table into more specific and manageable data according to a list of important genes or terms. This is very useful when a pathway, a condition, or a GO-Term is studied. The HOMO script has two inputs and one principal output. A table with the microarray data results is used as an input and a list of genes or important terms is used as a second input. The output is an adjusted table from the microarray results that contains only the genes included in the input list. HOMO's principal goal is to simplify the subsequent analyses to the microarray data. Availability HOMO.pl and a suite of example files are available by electronic mail request. PMID:23976833

Garcia-Chequer, Adda Jeanette; Jaimes-Diaz, Hueman; Ponce-Castañeda, Martha Verónica

2013-01-01

103

Reconstructing the ups and downs of primate brain evolution: implications for adaptive hypotheses and Homo floresiensis  

PubMed Central

Background Brain size is a key adaptive trait. It is often assumed that increasing brain size was a general evolutionary trend in primates, yet recent fossil discoveries have documented brain size decreases in some lineages, raising the question of how general a trend there was for brains to increase in mass over evolutionary time. We present the first systematic phylogenetic analysis designed to answer this question. Results We performed ancestral state reconstructions of three traits (absolute brain mass, absolute body mass, relative brain mass) using 37 extant and 23 extinct primate species and three approaches to ancestral state reconstruction: parsimony, maximum likelihood and Bayesian Markov-chain Monte Carlo. Both absolute and relative brain mass generally increased over evolutionary time, but body mass did not. Nevertheless both absolute and relative brain mass decreased along several branches. Applying these results to the contentious case of Homo floresiensis, we find a number of scenarios under which the proposed evolution of Homo floresiensis' small brain appears to be consistent with patterns observed along other lineages, dependent on body mass and phylogenetic position. Conclusions Our results confirm that brain expansion began early in primate evolution and show that increases occurred in all major clades. Only in terms of an increase in absolute mass does the human lineage appear particularly striking, with both the rate of proportional change in mass and relative brain size having episodes of greater expansion elsewhere on the primate phylogeny. However, decreases in brain mass also occurred along branches in all major clades, and we conclude that, while selection has acted to enlarge primate brains, in some lineages this trend has been reversed. Further analyses of the phylogenetic position of Homo floresiensis and better body mass estimates are required to confirm the plausibility of the evolution of its small brain mass. We find that for our dataset the Bayesian analysis for ancestral state reconstruction is least affected by inclusion of fossil data suggesting that this approach might be preferable for future studies on other taxa with a poor fossil record. PMID:20105283

2010-01-01

104

Fossil Energy Website  

NSDL National Science Digital Library

This site serves as a gathering point for US Department of Energy (USDOE) materials related to fossil energy. Well-organized and easily navigated, the Fossil Energy Website hosts a wealth of resources, including fossil energy news, related USDOE budget information, an events calendar, in-depth explorations of selected issues, speeches and testimony, technical reports, statistics, and an overview of fossil energy-related global activities, among others. Additional resources include regulatory information, a news headlines ticker, a free email update service, related links, and professional notices.

105

Plant Fossil Record  

NSDL National Science Digital Library

The International Organization of Palaeobotany (IOP) manages the Plant Fossil Record (PFR) database. The recently released version of the database, PFR2.2, offers descriptive details of most plant fossil genera and modern genera with fossil species. Based on "the scientific literature ... or museum collections," the database is organized into five sections: Genera (references for plant fossil genera published mostly before 1985), Descriptions (containing descriptive details of "the type specimens of more than 10,000 extinct plant genera"), Taxonomy (an "informal system of vascular plant classification" based on published schemes), Occurrences (distribution information and references), and Palaeo Maps.

106

Fossil Energy Program  

NASA Astrophysics Data System (ADS)

Increased utilization of coal and other fossil fuel alternatives as sources of clean energy is reported. The following topics are discussed: coal conversion development, chemical research and development, materials technology, component development and process evaluation studies, technical support to major liquefaction projects, process analysis and engineering evaluations, fossil energy environmental analysis, flue gas desulfurization, solid waste disposal, coal preparation waste utilization, plant control development, atmospheric fluidized bed coal combustor for cogeneration, TVA FBC demonstration plant program technical support, PFBC systems analysis, fossil fuel applications assessments, performance assurance system support for fossil energy projects, international energy technology assessment, and general equilibrium models of liquid and gaseous fuel supplies.

McNeese, L. E.

1981-01-01

107

Modes of fossil preservation  

USGS Publications Warehouse

The processes of geologic preservation are important for understanding the organisms represented by fossils. Some fossil differences are due to basic differences in organization of animals and plants, but the interpretation of fossils has also tended to be influenced by modes of preservation. Four modes of preservation generally can be distinguished: (1) Cellular permineralization ("petrifaction") preserves anatomical detail, and, occasionally, even cytologic structures. (2) Coalified compression, best illustrated by structures from coal but characteristic of many plant fossils in shale, preserves anatomical details in distorted form and produces surface replicas (impressions) on enclosing matrix. (3) Authigenic preservation replicates surface form or outline (molds and casts) prior to distortion by compression and, depending on cementation and timing, may intergrade with fossils that have been subject to compression. (4) Duripartic (hard part) preservation is characteristic of fossil skeletal remains, predominantly animal. Molds, pseudomorphs, or casts may form as bulk replacements following dissolution of the original fossil material, usually by leaching. Classification of the kinds of preservation in fossils will aid in identifying the processes responsible for modifying the fossil remains of both animals and plants. ?? 1975.

Schopf, J.M.

1975-01-01

108

Make a Model Fossil  

NSDL National Science Digital Library

This activity is a combination outdoor/indoor lab where students will collect natural materials from the environment and use them to create both a mold and cast model of a fossil. Students will learn how a fossil is formed and why scientists use models to help them understand how things work and develop.

109

Trace Fossil Image Database  

NSDL National Science Digital Library

This database from Emory University consists of images and basic information concerning trace fossils photographed by Anthony Martin. Included in this information is the formation, age, and locality of the specimen if known. Many of the images were originally photographed while in the field, and each type of trace fossil has numerous examples to browse through.

Anthony Martin

110

"It's Alive!" Fossil Activity  

NSDL National Science Digital Library

The first lab activity for the course is called "PaleontologyâPast, Present, and Future". In addition to discussing several documents related to present and future research directions in the field, students review a brief timeline of the historical development of paleontology as a science. Then they get their first opportunity to work directly with fossils. Students are presented with a set of fossil specimens in boxes (with no identifying labels). Each student selects one fossil of their own. They are asked to make and record very close, detailed observations of the specimen, and to sketch the fossil. Then they are told to "think like it's 1600." Someone has brought this object, taken out of the local rocks, for the student to investigate. The student must write a "proof" that this fossil was obviously once alive, and is not just an interesting mineral or rock formation. They can use their observations, compare the specimen to other objects with which they're familiar, resort to pure logic, or apply any other avenue of argumentation they think will help make their case. Note: In the next lab, on fossil preservation and taphonomy, the students revisit their fossil specimen, and determine its mode of preservation. Indeed, the student's "pet fossil" could be used throughout the course to illustrate various components of the course content.

Peg Yacobucci

111

Dinosaur Footprints & Fossils  

NSDL National Science Digital Library

In this activity, early learners simulate fossil prints in play dough or clay. Using plastic dinosaur feet to make footprints on their âmudâ (much as dinosaurs walked around their habitat) and harvest items (leaves, corn, twigs, acorns) to make impressions, learners simulate fossil prints. This resource includes open-ended discussion questions to encourage reflection.

Omsi

2004-01-01

112

Restoring Fossil Creek  

ERIC Educational Resources Information Center

Fossil Creek had been dammed for the past 90 years, and plans were underway to restore the stream. The creek runs through Central Arizona and flows from the high plateaus to the desert, cutting through the same formations that form the Grand Canyon. This article discusses the Fossil Creek monitoring project. In this project, students and teachers…

Flaccus, Kathleen; Vlieg, Julie; Marks, Jane C.; LeRoy, Carri J.

2004-01-01

113

Yawn Contagion and Empathy in Homo sapiens  

PubMed Central

The ability to share others' emotions, or empathy, is crucial for complex social interactions. Clinical, psychological, and neurobiological clues suggest a link between yawn contagion and empathy in humans (Homo sapiens). However, no behavioral evidence has been provided so far. We tested the effect of different variables (e.g., country of origin, sex, yawn characteristics) on yawn contagion by running mixed models applied to observational data collected over 1 year on adult (>16 years old) human subjects. Only social bonding predicted the occurrence, frequency, and latency of yawn contagion. As with other measures of empathy, the rate of contagion was greatest in response to kin, then friends, then acquaintances, and lastly strangers. Related individuals (r?0.25) showed the greatest contagion, in terms of both occurrence of yawning and frequency of yawns. Strangers and acquaintances showed a longer delay in the yawn response (latency) compared to friends and kin. This outcome suggests that the neuronal activation magnitude related to yawn contagion can differ as a function of subject familiarity. In conclusion, our results demonstrate that yawn contagion is primarily driven by the emotional closeness between individuals and not by other variables, such as gender and nationality. PMID:22163307

Norscia, Ivan; Palagi, Elisabetta

2011-01-01

114

Population Genomics Reveals Seahorses (Hippocampus erectus) of the Western Mid-Atlantic Coast to Be Residents Rather than Vagrants.  

PubMed

Understanding population structure and areas of demographic persistence and transients is critical for effective species management. However, direct observational evidence to address the geographic scale and delineation of ephemeral or persistent populations for many marine fishes is limited. The Lined seahorse (Hippocampus erectus) can be commonly found in three western Atlantic zoogeographic provinces, though inhabitants of the temperate northern Virginia Province are often considered tropical vagrants that only arrive during warm seasons from the southern provinces and perish as temperatures decline. Although genetics can locate regions of historical population persistence and isolation, previous evidence of Virginia Province persistence is only provisional due to limited genetic sampling (i.e., mitochondrial DNA and five nuclear loci). To test alternative hypotheses of historical persistence versus the ephemerality of a northern Virginia Province population we used a RADseq generated dataset consisting of 11,708 single nucleotide polymorphisms (SNP) sampled from individuals collected from the eastern Gulf of Mexico to Long Island, NY. Concordant results from genomic analyses all infer three genetically divergent subpopulations, and strongly support Virginia Province inhabitants as a genetically diverged and a historically persistent ancestral gene pool. These results suggest that individuals that emerge in coastal areas during the warm season can be considered "local" and supports offshore migration during the colder months. This research demonstrates how a large number of genes sampled across a geographical range can capture the diversity of coalescent histories (across loci) while inferring population history. Moreover, these results clearly demonstrate the utility of population genomic data to infer peripheral subpopulation persistence in difficult-to-observe species. PMID:25629166

Boehm, J T; Waldman, John; Robinson, John D; Hickerson, Michael J

2015-01-01

115

Population Genomics Reveals Seahorses (Hippocampus erectus) of the Western Mid-Atlantic Coast to Be Residents Rather than Vagrants  

PubMed Central

Understanding population structure and areas of demographic persistence and transients is critical for effective species management. However, direct observational evidence to address the geographic scale and delineation of ephemeral or persistent populations for many marine fishes is limited. The Lined seahorse (Hippocampus erectus) can be commonly found in three western Atlantic zoogeographic provinces, though inhabitants of the temperate northern Virginia Province are often considered tropical vagrants that only arrive during warm seasons from the southern provinces and perish as temperatures decline. Although genetics can locate regions of historical population persistence and isolation, previous evidence of Virginia Province persistence is only provisional due to limited genetic sampling (i.e., mitochondrial DNA and five nuclear loci). To test alternative hypotheses of historical persistence versus the ephemerality of a northern Virginia Province population we used a RADseq generated dataset consisting of 11,708 single nucleotide polymorphisms (SNP) sampled from individuals collected from the eastern Gulf of Mexico to Long Island, NY. Concordant results from genomic analyses all infer three genetically divergent subpopulations, and strongly support Virginia Province inhabitants as a genetically diverged and a historically persistent ancestral gene pool. These results suggest that individuals that emerge in coastal areas during the warm season can be considered “local” and supports offshore migration during the colder months. This research demonstrates how a large number of genes sampled across a geographical range can capture the diversity of coalescent histories (across loci) while inferring population history. Moreover, these results clearly demonstrate the utility of population genomic data to infer peripheral subpopulation persistence in difficult-to-observe species. PMID:25629166

Boehm, J. T.; Waldman, John; Robinson, John D.; Hickerson, Michael J.

2015-01-01

116

Fossil energy program  

NASA Astrophysics Data System (ADS)

The projects reported include those for coal conversion development, chemical research and development, materials technology, component development and process evaluation studies, technical support to major liquefaction projects, process analysis and engineering evaluations, fossil energy environmental analysis, flue gas desulfurization, plant control development, atmospheric fluidized bed coal combustor for cogeneration, TVA, FBC demonstration plant program technical support, and PFBC systems analysis. Fossil fuel application assessments, performance assurance system support for fossil energy projects, international energy technology assessment, and general equilibrium models of liquid and gaseous fuel supplies are presented.

McNeese, L. E.

1981-02-01

117

Fossil Identification Project  

NSDL National Science Digital Library

Students attend a class fieldtrip where over five locations across Tennessee representing three different geological time periods (Ordovician, Devonian, and Cretaceous) are visited. The students are required to collect 20 different taxa (5 of which must be unique to each student) and then using the knowledge they have gained in labs identify their taxa to species level. They must make a powerpoint presentation summarizing the paleocological and paleoclimatological information gained about each locality through the collection of the fossil taxa. The activity helps familiarize students with the geology of Tennessee and field collection of fossils in addition to lab identification of fossils.

Lobegeier, Melissa

118

Fossil energy program  

NASA Astrophysics Data System (ADS)

A compendium of monthly progress reports for the ORNL research and development programs that are in support of the increased utilization of coal and other fossil fuel alternatives as sources of clean energy is presented. The projects reported this month include those for coal conversion development, chemical research and development, materials technology, component development and process evaluation, technical support to major liquefaction projects, process analysis; and engineering evaluations, fossil energy environmental analysis, flue gas desulfurization, solid waste disposal, coal preparation and waste utilization, plant control development, atmospheric fluidized bed coal combustor for cogeneration, Tennessee Valley Authority Fluidized Bed Combustion demonstration plant program technical support, PFBC systems analysis, fossil fuel applications assessments, performance assurance system support for fossil energy projects, international energy technology assessment, and generalized equilibrium models of liquid and gaseous fuel supplies.

McNeese, L. E.

1981-03-01

119

Fossilized Dinosaur Bones  

NSDL National Science Digital Library

This slide show presents images of dinosaur bones and shows paleotologists at work excavating and preserving these fossils, the best evidence remaining of these long-lost creatures. A background essay and discussion questons are included.

120

The Great Fossil Find  

NSDL National Science Digital Library

On an imaginary fossil hunt, learners "find" (remove from envelope) paper "fossils" of some unknown creature, only a few at a time. Each time, they attempt to reconstruct the creature, and each time their interpretation tends to change as new pieces are "found." Use this as an introduction to the nature of science inquiry -- scientists don't always have all the information, scientists must form interpretations of the information, scientists must work together to come to consensus about interpretations.

Steve Rendak

1999-01-01

121

W. TECUMSEH FITCH School of Psychology, University of St Andrews  

E-print Network

engaged in. Did Australopithecines sing? Did Homo erectus drum? Did Neanderthals dance? These questions, 1995) are Aurignacian and associated with modern Homo sapiens (the Neanderthal "flutes" cited remain

Fitch, Tecumseh

122

Evidence of Evolution I. Fossils and the fossil record  

E-print Network

radioactive elements · Generally applied to igneous & metamorphic rocks, so what about fossils & sedimentary in the rocks deposited in those Eras. #12;#12;Why is the fossil record incomplete? · fossilization - "lucky in the rock! Accurate method for determining the age of fossils and rocks - Measures the decay of certain

Dever, Jennifer A.

123

The Sima de los Huesos (Burgos, northern Spain): palaeoenvironment and habitats of Homo heidelbergensis during the Middle Pleistocene  

NASA Astrophysics Data System (ADS)

Interpreting how environmental dynamics respond to global climate change and how this has affected human evolution and dispersal is an on-going topic of debate. During the early Middle Pleistocene (˜0.6-0.4 Ma), as compared to earlier, environmental conditions were relatively more stable, with longer climatic cycles alternating between open and forested landscapes. During this interval, humans spread successfully providing an important number of fossil sites where fossils or tools are reported. The Atapuerca-Sima de los Huesos (Burgos, northern Spain) site (Atapuerca-SH) is one of the earliest localities with hominin evidence in the European Middle Pleistocene, with the most important accumulation of Homo heidelbergensis so far. We have analyzed the abundant faunal record from Sima de los Huesos, which is mainly comprised of carnivores, in order to approach an interpretation of the palaeoenvironmental circumstances where these hominids inhabited within the Sierra. Other sites from Sierra de Atapuerca referred to the same Faunal Unit (FU 6), are roughly contemporaneous, and include important ungulates, which are here analyzed with Atapuerca-SH. Additional information provided by isotopic analysis helps elucidate the ancient ecology of taxa present in Sima de los Huesos allowing for an accurate portrayal of the setting in which humans lived. The timing of the spread of Homo heidelbergensis is dominated by a relative climatic and environmental stability and points to a landscape dominated by savannah-like open woodland.

García, Nuria; Arsuaga, Juan Luis

2011-06-01

124

LB1 and LB6 Homo floresiensis are not modern human (Homo sapiens) cretins.  

PubMed

Excavations in the late Pleistocene deposits at Liang Bua cave, Flores, have uncovered the skeletal remains of several small-bodied and small-brained hominins in association with stone artefacts and the bones of Stegodon. Due to their combination of plesiomorphic, unique and derived traits, they were ascribed to a new species, Homo floresiensis, which, along with Stegodon, appears to have become extinct ?17 ka (thousand years ago). However, recently it has been argued that several characteristics of H. floresiensis were consistent with dwarfism and evidence of delayed development in modern human (Homo sapiens) myxoedematous endemic (ME) cretins. This research compares the skeletal and dental morphology in H. floresiensis with the clinical and osteological indicators of cretinism, and the traits that have been argued to be associated with ME cretinism in LB1 and LB6. Contrary to published claims, morphological and statistical comparisons did not identify the distinctive skeletal and dental indicators of cretinism in LB1 or LB6 H. floresiensis. Brain mass, skeletal proportions, epiphyseal union, orofacial morphology, dental development, size of the pituitary fossa and development of the paranasal sinuses, vault bone thickness and dimensions of the hands and feet all distinguish H. floresiensis from modern humans with ME cretinism. The research team responsible for the diagnosis of ME cretinism had not examined the original H. floresiensis skeletal materials, and perhaps, as a result, their research confused taphonomic damage with evidence of disease, and thus contained critical errors of fact and interpretation. Behavioural scenarios attempting to explain the presence of cretinous H. sapiens in the Liang Bua Pleistocene deposits, but not unaffected H. sapiens, are both unnecessary and not supported by the available archaeological and geochronological evidence from Flores. PMID:22277102

Brown, Peter

2012-02-01

125

Gas-phase Dissociation of homo-DNA Oligonucleotides  

NASA Astrophysics Data System (ADS)

Synthetic modified oligonucleotides are of interest for diagnostic and therapeutic applications, as their biological stability, pairing selectivity, and binding strength can be considerably increased by the incorporation of unnatural structural elements. Homo-DNA is an oligonucleotide homologue based on dideoxy-hexopyranosyl sugar moieties, which follows the Watson-Crick A-T and G-C base pairing system, but does not hybridize with complementary natural DNA and RNA. Homo-DNA has found application as a bioorthogonal element in templated chemistry applications. The gas-phase dissociation of homo-DNA has been investigated by ESI-MS/MS and MALDI-MS/MS, and mechanistic aspects of its gas-phase dissociation are discussed. Experiments revealed a charge state dependent preference for the loss of nucleobases, which are released either as neutrals or as anions. In contrast to DNA, nucleobase loss from homo-DNA was found to be decoupled from backbone cleavage, thus resulting in stable products. This renders an additional stage of ion activation necessary in order to generate sequence-defining fragment ions. Upon MS3 of the primary base-loss ion, homo-DNA was found to exhibit unspecific backbone dissociation resulting in a balanced distribution of all fragment ion series.

Stucki, Silvan R.; Désiron, Camille; Nyakas, Adrien; Marti, Simon; Leumann, Christian J.; Schürch, Stefan

2013-12-01

126

The Astonishing Micropygmies  

NSDL National Science Digital Library

Access to the article is free, however registration and sign-in are required. The stunning discovery of a Late Pleistocene hominin skeleton, on the Indonesian island of Flores has thrown the anthropological world into a frenzy. The primitive and derived features of the skeleton, but most curiously its tiny stature suggest a new species of diminutive Homo erectus called H. floresiensis. In a provocative Perspective, Jared Diamond provides a scintillating synthesis of the evidence for a new H. erectus species and debates the reasons why the fossil remains of this pygmy hominin have only now been discovered.

Jared Diamond (University of California at Los Angeles; Geography Department)

2004-12-17

127

Earliest human occupations at Dmanisi (Georgian Caucasus) dated to 1.85–1.78 Ma  

PubMed Central

The early Pleistocene colonization of temperate Eurasia by Homo erectus was not only a significant biogeographic event but also a major evolutionary threshold. Dmanisi's rich collection of hominin fossils, revealing a population that was small-brained with both primitive and derived skeletal traits, has been dated to the earliest Upper Matuyama chron (ca. 1.77 Ma). Here we present archaeological and geologic evidence that push back Dmanisi's first occupations to shortly after 1.85 Ma and document repeated use of the site over the last half of the Olduvai subchron, 1.85–1.78 Ma. These discoveries show that the southern Caucasus was occupied repeatedly before Dmanisi's hominin fossil assemblage accumulated, strengthening the probability that this was part of a core area for the colonization of Eurasia. The secure age for Dmanisi's first occupations reveals that Eurasia was probably occupied before Homo erectus appears in the East African fossil record. PMID:21646521

Ferring, Reid; Oms, Oriol; Agustí, Jordi; Berna, Francesco; Nioradze, Medea; Shelia, Teona; Tappen, Martha; Vekua, Abesalom; Zhvania, David; Lordkipanidze, David

2011-01-01

128

The functions of sound production in the lined seahorse, Hippocampus erectus, and effects of loud ambient noise on its behavior and physiology in captive environments  

NASA Astrophysics Data System (ADS)

Loud noise in aquaria represents a cacophonous environment for captive fishes. I tested the effects of loud noise on acoustic communication, feeding behavior, courtship behavior, and the stress response of the lined seahorse, Hippocampus erectus. Total Root Mean Square (RMS) power of ambient noise to which seahorses are exposed in captivity varies widely but averages 126.1 +/- 0.8 deciBels with reference to one micropascal (dB re: 1 muPa) at the middle of the water column and 133.7 +/- 1.1 dB at the tank bottom, whereas ambient noise in the wild averages 119.6 +/- 3.5 dB. Hearing sensitivity of H. erectus, measured from auditory evoked potentials, demonstrated maximum spectrum-level sensitivities of 105.0 +/- 1.5 dB and 3.5 x 10-3 + 7.6 x 10-4 m/s2 at 200 Hz; which is characteristic of hearing generalists. H. erectus produces acoustic clicks with mean peak spectrum-level amplitudes of 94.3 +/- 0.9 dB at 232 +/- 16 Hz and 1.5 x 10 -3 +/- 1.9 x 10-4 m/s2 at 265 +/- 22 Hz. Frequency matching of clicks to best hearing sensitivity, and estimates of audition of broadband signals suggest that seahorses may hear conspecific clicks, especially in terms of particle motion. Behavioral investigations revealed that clicking did not improve prey capture proficiency. However, animals clicked more often as time progressed in a courtship sequence, and mates performed more courtship behaviors with control animals than with muted animals, lending additional evidence to the role of clicking as an acoustic signal during courtship. Despite loud noise and the role of clicking in communication, masking of the acoustic signal was not demonstrated. Seahorses exposed to loud noise in aquaria for one month demonstrated physiological, chronic stress responses: reduced weight and body condition, and increased heterophil to lymphocyte ratio. Behavioral alterations were characterized by greater mean and variance of activity among animals housed in loud tanks in the first week, followed by habituation. By week four, animals in loud tanks demonstrated variable performance of clicking and piping, putative distress behaviors. Despite the physiological stress response, animals in loud tanks did not reduce feeding response or courtship behavior, suggesting allostasis.

Anderson, Paul August

129

Fossil Fuels: Capstone  

NSDL National Science Digital Library

This lesson summarizes our dependency upon fossil fuels, pointing out that there are very few aspects of our daily life that are not impacted by their use. The discussion centers around whether these fuels could be replaced and makes the point that there is a significant percentage of them which is used to manufacture products and is not simply burned for energy. The lesson includes an activity in which students use an online calculator to estimate how much of each fossil fuel they are responsible for consuming each year.

John Pratte

130

Dinoflagellata: Fossil Record  

NSDL National Science Digital Library

Information on this page pertains to dinoflagellates, the fossil record of which may extend into the Precambrian. Spherical organic-walled microfossils known as acritarchs, some of which may be dinoflagellate hystrichospheres, first appear in rocks about 1.8 billion years old. Exactly what the acritarchs were is not known with certainty; they probably included a number of clades of eukaryotic algae, and are thus a form taxon, including all those spore-like fossils which have not been conclusively assigned to another group.

131

Science Sampler: Fossil detectives  

NSDL National Science Digital Library

Middle school students are transformed into Fossil detectives as they examine the fossil record and use evidence about paleo-environments to develop an understanding of structure and function in living systems and changes over time in Earths history. In this enrichment activity, students work in teams to research an assigned geologic time period. They determine available habitats, food sources and types (animal, plant; woody, herbaceous, etc.), cover sources, methods of getting food, defense, and reproduction that would allow an animal to live in the assigned paleoenvironment. In culmination of their efforts, students create a diorama to display their findings.

Bourdeau, Virginia

2006-07-01

132

Fossil reptilian gelatins.  

PubMed

1. Studies have been made of products obtained by treating several reptilian fossil bones with dilute formic acid. 2. Their amounts and compositions have been compared with those of similarly treated fresh and Pleistocene bones. 3. Fewer and small peptides are obtained from the older fossils but in only one instance was the composition significantly different from that of the total protein. 4. For the collagenous proteins aspartic acid was the most readily freed by hydrolysis; for these older proteins it is alanine. 5. Unlike the Pleistocene proteins, the chromatograms from these older proteins have always had peaks in the position of beta-alanine, and usually others of unidentified origin. PMID:318304

Wyckoff, R W; Davidson, F D

1979-01-01

133

What is a Fossil?  

NSDL National Science Digital Library

In this activity about dinosaurs, learners explore how and why fossils form. First, learners are introduced to dinosaur fossils by reading the book "Bones, Bones, Dinosaur Bones" by Byron Barton. Then, learners make impressions in clay using a seashell, pennies, dinosaur teeth and other items. Next, learners make dinosaur tracks in the clay as they "walk" plastic models across the soft clay. Learners also use sponges pre-cut in the shape of dinosaur feet to make more tracks. This activity is featured on page 29 of the "Dinosphere" unit of study for K-2 learners.

2014-04-14

134

Genotype-specific responses of Bromus erectus to elevated CO{sub 2} at different levels of biodiversity and endophyte infection - a field experiment  

SciTech Connect

In 1994 we initiated a long-term field experiment in a calcareous grassland to study the effects of elevated CO{sub 2} on individuals, populations, and communities. Clonal replicates of 54 genotypes of the dominant grass Bromus erectus were grown in communities planted at three levels of biodiversity (5-, 12-, 31-species plots) and exposed to ambient and elevated CO{sub 2}. The same genotypes were also individually grown in tubes within the field plots. Some genotypes were infected by the endophytic fungus Epichloee typhina. Elevated CO{sub 2} had no significant effects on plant growth, however, there was large variation among genotypes in all measured characters. A significant CO{sub 2}-by-genotype interaction was found for leaf length in the competition-free tubes. Infection by the endophyte led to the abortion of all inflorescences but increased vegetative growth, especially under competitive conditions.

Steinger, T.; Groppe, K.; Schmid, B. [Univ. of Basel (Switzerland)]|[Univ. of Zurich (Switzerland)

1995-06-01

135

Fossil Evidence of Bipedalism  

NSDL National Science Digital Library

This video segment adapted from NOVA shows how scientists use the fossil record to trace when early human ancestors and related species began walking on two legs instead of four, and to determine whether they were more apelike or human in appearance.

2010-03-10

136

Therapod Fossil Hunt Dispatch  

NSDL National Science Digital Library

This online article reports on the finding of a dromaeosaur fossil, the best specimen to date to show that feathers existed long before modern birds and flight. The research was a collaboration between the American Museum of Natural History and the Geological Museum of China.

137

Fossils and Minerals  

NSDL National Science Digital Library

This site from the Black Hills Institute features information about different types of fossils, minerals, meteorites, and geology in general. Each topic has a brief description, with links to a more detailed explanation. Various samples and books are abailable for purchase on the site.

Research, Inc. B.

138

Rethinking Fossil Fuels  

NSDL National Science Digital Library

Climate change and fossil fuel use are connected. It would serve the world well to: begin a moratorium on coal-fired power plants; explore and use renewable energy; insist on immediate action from world governments; and penalize industries putting excess CO2 into the atmosphere.

James Hansen (NASA Goddard Institute for Space Studies; )

2008-09-09

139

Fossil Halls: Vertebrate Evolution  

NSDL National Science Digital Library

Part of a larger virtual tour of the Museum's famed Fossil Halls, this Web site has an interactive cladogram with 20 clickable evolutionary branching points. It shows vertebrate evolution for the following three AMNH halls: Hall of Vertebrate Origins, Hall of Dinosaurs and Hall of Mammals and Their Extinct Relatives.

140

Culture, Speciation and the Genus Homo in Early Humans  

Microsoft Academic Search

Human behaviour, in addition to morphology, is essential to identify man. The characteristics of cultural behaviour are expressed by planning in tool making and territorial organization and by their meaning in the context of life. Cultural behaviour enriched the adaptive strategies of the human species and took on significance in the definition of the genus Homo since H. habilis\\/H. rudolfensis.

Fiorenzo Facchini

2006-01-01

141

Unsolved Problems in Comparing Brain Sizes in Homo Sapiens  

Microsoft Academic Search

When brain size is compared across taxonomic levels, there is a clear relation between body parameters and brain size. It is generally stated that the correlation between brain size and body parameters becomes very small at the species level (Aboitiz, 1996), but this is not the case for Homo sapiens where there is a strong correlation between brain size and

M. Peters; L. Jäncke; J. F. Staiger; G. Schlaug; Y. Huang; H. Steinmetzi

1998-01-01

142

Sterically controlled naphthalene homo-oligoamides with novel structural architectures.  

PubMed

Herein we report novel naphthalene homo-oligoamides, derived from 4-amino-3-methoxy-naphthalene-2-carboxylic acid and 4-amino-1-methoxy-naphthalene-2-carboxylic acid as monomer building blocks, that display an anti-periplanar arrangement of the naphthyl rings, primarily induced by steric interactions between adjacent groups and functionalities. PMID:19462058

Prabhakaran, Panchami; Puranik, Vedavati G; Chandran, Jima N; Rajamohanan, P R; Hofmann, Hans-Jörg; Sanjayan, Gangadhar J

2009-06-01

143

Sustainability of Fossil Fuels  

NASA Astrophysics Data System (ADS)

For a sustainable world economy, energy is a bottleneck. Energy is at the basis of a modern, technological society, but unlike materials it cannot be recycled. Energy or more precisely "negentropy" (the opposite of entropy) is always consumed. Thus, one either accepts the use of large but finite resources or must stay within the limits imposed by dilute but self-renewing resources like sunlight. The challenge of sustainable energy is exacerbated by likely growth in world energy demand due to increased population and increased wealth. Most of the world still has to undergo the transition to a wealthy, stable society with the near zero population growth that characterizes a modern industrial society. This represents a huge unmet demand. If ten billion people were to consume energy like North Americans do today, world energy demand would be ten times higher. In addition, technological advances while often improving energy efficiency tend to raise energy demand by offering more opportunity for consumption. Energy consumption still increases at close to the 2.3% per year that would lead to a tenfold increase over the course of the next century. Meeting future energy demands while phasing out fossil fuels appears extremely difficult. Instead, the world needs sustainable or nearly sustainable fossil fuels. I propose the following definition of sustainable under which fossil fuels would well qualify: The use of a technology or resource is sustainable if the intended and unintended consequences will not force its abandonment within a reasonable planning horizon. Of course sustainable technologies must not be limited by resource depletion but this is only one of many concerns. Environmental impacts, excessive land use, and other constraints can equally limit the use of a technology and thus render it unsustainable. In the foreseeable future, fossil fuels are not limited by resource depletion. However, environmental concerns based on climate change and other environmental effects of injecting excess carbon into the environment need to be eliminated before fossil fuels can be considered sustainable. Sustainable fossil fuel use would likely rely on abundant, low-grade hydrocarbons like coal, tar, and shale. It would require a closed cycle approach in which carbon is extracted from the ground, processed for its energy content, and returned into safe and stable sinks for permanent disposal. Such sequestration technologies already exist and more advanced approaches that could maintain access to fossil energy for centuries are on the drawing boards. I will review these options and outline a pathway towards a zero emission fossil fuel based economy that could provide energy at prices comparable to those of today for several centuries. A successful implementation will depend not only on technological advances but also on the development of economic institutions that allow one to pay for the required carbon management. If done correctly the markets will decide whether renewable energy, or sustainable fossil energy provides a better choice.

Lackner, K. S.

2002-05-01

144

Flexible Serial Response Learning by Pigeons (Columba livia) and Humans (Homo sapiens)  

E-print Network

Flexible Serial Response Learning by Pigeons (Columba livia) and Humans (Homo sapiens) Walter T to each target was measured. Pigeons (Columba livia) and humans (Homo sapiens) both showed response time

Herbranson, Wally

145

The largest fossil rodent  

PubMed Central

The discovery of an exceptionally well-preserved skull permits the description of the new South American fossil species of the rodent, Josephoartigasia monesi sp. nov. (family: Dinomyidae; Rodentia: Hystricognathi: Caviomorpha). This species with estimated body mass of nearly 1000?kg is the largest yet recorded. The skull sheds new light on the anatomy of the extinct giant rodents of the Dinomyidae, which are known mostly from isolated teeth and incomplete mandible remains. The fossil derives from San José Formation, Uruguay, usually assigned to the Pliocene–Pleistocene (4–2?Myr ago), and the proposed palaeoenvironment where this rodent lived was characterized as an estuarine or deltaic system with forest communities. PMID:18198140

Rinderknecht, Andrés; Blanco, R. Ernesto

2008-01-01

146

Bibliography of Fossil Vertebrates  

NSDL National Science Digital Library

The Society of Vertebrate Paleontology (SVP), one of most reputable American paleontological societies, sponsors this online edition of its Bibliography of Fossil Vertebrates. The database, which currently covers the years 1509-1958 and 1981-1993 with approximately 112,000 references, is searchable by author, subject, taxon, language, editor, and journal book or volume title. A help page with query instructions for the somewhat finicky search engine is provided.

1997-01-01

147

The Unknown Fossil Report  

NSDL National Science Digital Library

This project challenges the students ingenuity, creativity, and resourcefulness! They each receive a fossil of unknown identity (general geographic locality may be given, e.g., I-55 south of St. Louis, MO). The specimen is described in as much detail as possible. Their report should include taxonomic classification (as complete as they can), age, paleoecology, Earth history, and other interpretations they can infer. Identification may require library work, Internet search, etc.

Max Reams

148

Fossil Halls: Timelines  

NSDL National Science Digital Library

Part of a larger virtual tour of the Museum's famed Fossil Halls, this Web site allows students to travel back in time to several prehistoric points in the history of Earth. At each, they'll find a fleshed-out portrait of the period's creatures and their environment. The eight periods students will visit, some of which include more than one point-in-time snapshot, are Pleistocene, Miocene, Oligocene, Eocene, Cretaceous, Jurassic, Permian and Devonian Periods.

149

Fossil Microbes on Mars?  

NSDL National Science Digital Library

This online article, from Cosmic Horizons: Astronomy at the Cutting Edge, reports on the controversial discovery of Martian meteorite ALH84001. In 1996, a team of scientists led by David McKay of NASAâs Johnson Space Flight Center announced that they had discovered evidence for microscopic fossil life in this meteorite from Mars. From the start, the evidence was both fascinating and controversial, and to this day it remains so.

150

Restoring Fossil Creek  

NSDL National Science Digital Library

As part of an ongoing environmental project and partnership with a local university, high school students monitor changes to Fossil Creek in Arizona. Components of the project include fish behavior studies, responses to fishing, water chemistry measurements, aquatic invertebrate studies, photographic recording, riparian habitat transects, and small mammal trapping transects. The data collected will ultimately provide an invaluable annual record for students, working scientists, and the wider community as changes are monitored over time.

Leroy, Carri J.; Marks, Jane C.; Vlieg, Julie; Flaccus, Kathleen

2004-07-01

151

Fossil Age Estimation Model  

NSDL National Science Digital Library

In this activity (page 1 of the PDF), learners will model how paleontologists estimate the age of fossil discoveries by extracting âfossilâ playing cards from newspapers stacked in chronological order. Learners identify the âageâ of the card based on the âevidenceâ (printed date) in the surrounding pages. They then create a data table and graph and analyze their findings. Use this activity to introduce learners to paleontology and geology. Relates to the linked video, DragonflyTV GPS: Dinosaurs.

Twin Cities Public Television, Inc.

2006-01-01

152

Living and Fossil Macrocyprididae  

E-print Network

behave in one way and sometimes in the other. You cannot lay down general rules of what is important in classification and what is not. Peter C. Sylvester-Bradley, 1969, p. 245 LIVING AND FOSSIL MACROCYPRIDIDAE (OSTRACODA) Rosalie F. Maddocks Department... are redescribed from type and additional specimens, 54 new species are named, and 48 additional species are described in open nomenclature. Appendage and genital characters are described for 73 of these species. A review of more than 100 additional species...

Maddocks, R. F.

1990-02-27

153

Schewel and Schipper 1 FOSSIL FREIGHT: HOW MUCH FOSSIL FUEL DOES IT TAKE TO MOVE FOSSIL1  

E-print Network

Schewel and Schipper 1 FOSSIL FREIGHT: HOW MUCH FOSSIL FUEL DOES IT TAKE TO MOVE FOSSIL1 FUEL?2 #12;Schewel and Schipper 2 Abstract1 This paper asks as the question: how much fossil fuel does it take to move fossil fuel inside the U.S.? An2 understanding of this "fossil freight", which takes up

Kammen, Daniel M.

154

Fossilized Dinosaur Teeth Adaptations  

NSDL National Science Digital Library

In this activity, learners use models of fossilized dinosaur teeth to understand how dinosaur teeth were used. Learners specifically research Tyrannosaurus rex and Triceratops horridus dinosaurs and determine that Triceratops teeth work the way pliers and scissors operate, and T. rex teeth are like sharp knives. Learners match and sort dinosaurs by the type and use of their teeth. This activity is featured on pp.14-18 (part of a lesson that begins on p.7) of the "Dinosphere" unit of study for grades 3-5.

Crosslin, Rick; Fortney, Mary; Indianapolis, The C.

2004-01-01

155

A Fossil Thermometer  

NSDL National Science Digital Library

In this activity, students calculate temperatures during a time in the geologic record when rapid warming occurred using a well known method called 'leaf-margin analysis.' Students determine the percentage of the species that have leaves with smooth edges, as opposed to toothed, or jagged, edges. Facsimiles of fossil leaves from two collection sites are examined, categorized, and the data is plugged into an equation to provide an estimate of paleotemperature for two sites in the Bighorn Basin. It also introduces students to a Smithsonian scientist who worked on the excavation sites and did the analysis.

Institution, Smithsonian; Institute, Smithsonian

156

Fossil Mammal Research Group  

NSDL National Science Digital Library

This website presents the Fossil Mammal Research Group whose "members are palaeontologists and archaeologists as well as palaeoenvironmental specialists in the School of Biological & Earth Sciences, Liverpool John Moores University, UK." Subjects of study by the Research group include mammalian fauna development over the past 30 million years, Plio-Pleistocene and Holocene climate change, and more. The website links to subpages for a list of Publications from 1998-2004, Major Projects going on around the world, Conferences, and relevant links. The site also provides a page presenting group members along with their research interests and email addresses.

157

Unearthing Important Fossils  

NSDL National Science Digital Library

Over the past several weeks, a flurry of dinosaur and other fossil discoveries have reached the mainstream news. From the two 530-million-year-old fish-like creatures that could be the earliest known vertebrates found in China, to the bones of two dinosaurs in Madagascar that may be the oldest dinosaurs ever found, to the "60-ton giraffe-like creature" (3) found in Oklahoma (called Sauroposeidon proteles, or "thunder lizard"), paleontologists are immersed in discovery. The significance of the first discovery is triggering excitement among paleontologists, worldwide. In particular, the discovery of the two "fish-like" fossils in China (to be published in this week's journal Nature) indicates that fish (i.e., vertebrates) evolved much earlier than previously thought and that "the rates of evolution in the oceans during the Cambrian period must have been exceptionally fast" (1). This week's In The News discusses some of the recently unveiled discoveries and provides background information and resources on vertebrate paleontology.

Payne, Laura X.

158

Fossil Microorganisms in Archaean  

NASA Technical Reports Server (NTRS)

Ancient Archean and Proterozoic rocks are the model objects for investigation of rocks comprising astromaterials. The first of Archean fossil microorganisms from Baltic shield have been reported at the last SPIE Conference in 2005. Since this confeence biomorphic structures have been revealed in Archean rocks of Karelia. It was determined that there are 3 types of such bion structures: 1. structures found in situ, in other words microorganisms even-aged with rock matrix, that is real Archean fossils biomorphic structures, that is to say forms inhabited early formed rocks, and 3. younger than Archean-Protherozoic minerali microorganisms, that is later contamination. We made attempt to differentiate these 3 types of findings and tried to understand of burial of microorganisms. The structures belongs (from our point of view) to the first type, or real Archean, forms were under examination. Practical investigation of ancient microorganisms from Green-Stone-Belt of Northern Karelia turns to be very perspective. It shows that even in such ancient time as Archean ancient diverse world existed. Moreover probably such relatively highly organized cyanobacteria and perhaps eukaryotic formes existed in Archean world.

Astafleva, Marina; Hoover, Richard; Rozanov, Alexei; Vrevskiy, A.

2006-01-01

159

Homo sapiens, Homo neanderthalensis and the Denisova specimen: New insights on their evolutionary histories using whole-genome comparisons  

PubMed Central

After a brief review of the most recent findings in the study of human evolution, an extensive comparison of the complete genomes of our nearest relative, the chimpanzee (Pan troglodytes), of extant Homo sapiens, archaic Homo neanderthalensis and the Denisova specimen were made. The focus was on non-synonymous mutations, which consequently had an impact on protein levels and these changes were classified according to degree of effect. A total of 10,447 non-synonymous substitutions were found in which the derived allele is fixed or nearly fixed in humans as compared to chimpanzee. Their most frequent location was on chromosome 21. Their presence was then searched in the two archaic genomes. Mutations in 381 genes would imply radical amino acid changes, with a fraction of these related to olfaction and other important physiological processes. Eight new alleles were identified in the Neanderthal and/or Denisova genetic pools. Four others, possibly affecting cognition, occured both in the sapiens and two other archaic genomes. The selective sweep that gave rise to Homo sapiens could, therefore, have initiated before the modern/archaic human divergence. PMID:23413113

Paixão-Côrtes, Vanessa Rodrigues; Viscardi, Lucas Henrique; Salzano, Francisco Mauro; Hünemeier, Tábita; Bortolini, Maria Cátira

2012-01-01

160

Fossils 2: Uncovering the Facts  

NSDL National Science Digital Library

In Fossils and Dinosaurs, the first lesson of this two lesson series, students learned the differences between facts and ideas that are extrapolated from fossil evidence. This lesson allows students to go through an 'interview' with the remains of a Protoceratops. In preparation for the interview, students first brainstorm the questions they would like answers to, and then narrow their questions to those that can be answered by studying the Protoceratops fossils.

Science Netlinks

2001-10-20

161

Learning from the Fossil Record  

NSDL National Science Digital Library

Another interesting and helpful resource from the University of California Berkeley Museum of Paleontology is the Learning from the Fossil Record Web site. Educators will find a list of over twenty fossil related classroom activities presented by different authors with titles such as Building a Topographic Model, Determining the Age Of Rocks and Fossils, Fossilization and Adaptation, the Dinosaur Body Structure, Microfossils, and other interesting subjects. The detailed descriptions include everything needed to complete the individual exercises including background information, procedures, and downloads. The unique collection should be a helpful addition to any junior high or high school science curriculum.

162

Fossil groups of galaxies: Are they groups? Are they fossils?  

Microsoft Academic Search

Fossil groups present a puzzle to current theories of structure formation. Despite the low number of bright galaxies, their high velocity dispersions and high TX indicate cluster-like potential wells. Measured concentration parameters seem very high indicating early formation epochs in contradiction with the observed lack of large and well defined cooling cores. There are very few fossil groups with good

Renato de Alencar Dupke; Eric Miller; Claudia Mendes de Oliveira; Laerte Sodre; Eli Rykoff; Raimundo Lopes de Oliveira; Rob Proctor

2010-01-01

163

Evidence of Evolution I. Fossils and the fossil record  

E-print Network

to igneous & metamorphic rocks, so what about fossils & sedimentary rocks? · "bracketing" · And organic in some regions than others Eras defined by major changes in the types of fossils found in the rocks://www.pbs.org/wgbh/evolution/library/03/3/l_033_01.html Radiometric dating ­ the clock in the rock! Accurate method for determining

Dever, Jennifer A.

164

Fossil turbulence and fossil turbulence waves can be dangerous  

E-print Network

Turbulence is defined as an eddy-like state of fluid motion where the inertial-vortex forces of the eddies are larger than any other forces that tend to damp the eddies out. By this definition, turbulence always cascades from small scales where vorticity is created to larger scales where turbulence fossilizes. Fossil turbulence is any perturbation in a hydrophysical field produced by turbulence that persists after the fluid is no longer turbulent at the scale of the perturbation. Fossil turbulence patterns and fossil turbulence waves preserve and propagate energy and information about previous turbulence. Ignorance of fossil turbulence properties can be dangerous. Examples include the Osama bin Laden helicopter crash and the Air France 447 Airbus crash, both unfairly blamed on the pilots. Observations support the proposed definitions, and suggest even direct numerical simulations of turbulence require caution.

Carl H Gibson

2012-11-25

165

Life of a Vertebrate Fossil  

NSDL National Science Digital Library

Unless you have a very large research grant, it can be difficult to find fossil bones. Fortunately, this very fine online learning module from the Smithsonian's Natural History Museum can help both young and old to learn about locating fossil bones, among other things. Through this multimedia feature created by the History Museum's department of paleobiology, visitors will learn what paleontologists do in each stage in the life of a vertebrate fossil. With the assistance of short video clips, interactive diagrams, and photographs, visitors will learn about how fossils are prepared for examination and how scientists unravel the stories of these paleontological finds. Finally, visitors will also learn how fossils are stored and preserved.

166

An Enlarged Parietal Foramen in the Late Archaic Xujiayao 11 Neurocranium from Northern China, and Rare Anomalies among Pleistocene Homo  

PubMed Central

We report here a neurocranial abnormality previously undescribed in Pleistocene human fossils, an enlarged parietal foramen (EPF) in the early Late Pleistocene Xujiayao 11 parietal bones from the Xujiayao (Houjiayao) site, northern China. Xujiayao 11 is a pair of partial posteromedial parietal bones from an adult. It exhibits thick cranial vault bones, arachnoid granulations, a deviated posterior sagittal suture, and a unilateral (right) parietal lacuna with a posteriorly-directed and enlarged endocranial vascular sulcus. Differential diagnosis indicates that the perforation is a congenital defect, an enlarged parietal foramen, commonly associated with cerebral venous and cranial vault anomalies. It was not lethal given the individual’s age-at-death, but it may have been associated with secondary neurological deficiencies. The fossil constitutes the oldest evidence in human evolution of this very rare condition (a single enlarged parietal foramen). In combination with developmental and degenerative abnormalities in other Pleistocene human remains, it suggests demographic and survival patterns among Pleistocene Homo that led to an elevated frequency of conditions unknown or rare among recent humans. PMID:23527224

Xing, Song

2013-01-01

167

Organic molecules as chemical fossils - The molecular fossil record  

NASA Technical Reports Server (NTRS)

The study of biochemical clues to the early earth and the origin of life is discussed. The methods used in such investigation are described, including the extraction, fractionation, and analysis of geolipids and the analysis of kerogen. The occurrence of molecular fossils in the geological record is examined, discussing proposed precursor-product relationships and the molecular assessment of deep sea sediments, ancient sediments, and crude petroleums. Alterations in the molecular record due to diagenesis and catagenesis are considered, and the use of microbial lipids as molecular fossils is discussed. The results of searches for molecular fossils in Precambrian sediments are assessed.

Eglinton, G.

1983-01-01

168

Homo-Roche Ester Derivatives By Asymmetric Hydrogenation and Organocatalysis  

PubMed Central

Asymmetric hydrogenation routes to homologs of The Roche ester tend to be restricted to hydrogenations of itaconic acid derivatives, ie substrates that contain a relatively unhindered, 1,1-disubstituted, alkene. This is because in hydrogenations mediated by RhP2 complexes, the typical catalysts, it is difficult to obtain high conversions using the alternative substrate for the same product, the isomeric trisubstituted alkenes (D in the text). However, chemoselective modification of the identical functional groups in itaconic acid derivatives are difficult, hence it would be favorable to use the trisubstituted alkene. Trisubstituted alkene substrates can be hydrogenated with high conversions using chiral analogs of Crabtree’s catalyst of the type IrN(carbene). This paper demonstrates such reactions are scalable (tens of grams) and can be manipulated to give optically pure homo-Roche ester chirons. Organocatalytic fluorination, chlorination, and amination of the homo-Roche building blocks was performed to demonstrate that they could be easily transformed into functionalized materials with two chiral centers and ?,?-groups that provide extensive scope for modifications. A synthesis of (S,S)- and (R,S)-?-hydroxyvaline was performed to illustrate one application of the amination product. PMID:24219839

Khumsubdee, Sakunchai; Zhou, Hua; Burgess, Kevin

2013-01-01

169

Fossil fuel furnace reactor  

DOEpatents

A fossil fuel furnace reactor is provided for simulating a continuous processing plant with a batch reactor. An internal reaction vessel contains a batch of shale oil, with the vessel having a relatively thin wall thickness for a heat transfer rate effective to simulate a process temperature history in the selected continuous processing plant. A heater jacket is disposed about the reactor vessel and defines a number of independent controllable temperature zones axially spaced along the reaction vessel. Each temperature zone can be energized to simulate a time-temperature history of process material through the continuous plant. A pressure vessel contains both the heater jacket and the reaction vessel at an operating pressure functionally selected to simulate the continuous processing plant. The process yield from the oil shale may be used as feedback information to software simulating operation of the continuous plant to provide operating parameters, i.e., temperature profiles, ambient atmosphere, operating pressure, material feed rates, etc., for simulation in the batch reactor.

Parkinson, William J. (Los Alamos, NM)

1987-01-01

170

FOSSIL2 energy policy model documentation: FOSSIL2 documentation  

SciTech Connect

This report discusses the structure, derivations, assumptions, and mathematical formulation of the FOSSIL2 model. Each major facet of the model - supply/demand interactions, industry financing, and production - has been designed to parallel closely the actual cause/effect relationships determining the behavior of the United States energy system. The data base for the FOSSIL2 program is large, as is appropriate for a system dynamics simulation model. When possible, all data were obtained from sources well known to experts in the energy field. Cost and resource estimates are based on DOE data whenever possible. This report presents the FOSSIL2 model at several levels. Volumes II and III of this report list the equations that comprise the FOSSIL2 model, along with variable definitions and a cross-reference list of the model variables. Volume III lists the model equations and a one line definition for equations, in a short, readable format.

None

1980-10-01

171

A New Skull of Early Homo from Dmanisi, Georgia  

Microsoft Academic Search

Another hominid skull has been recovered at Dmanisi (Republic of Georgia) from the same strata in which hominid remains have been reported previously. The Dmanisi site dated to ~1.75 million years ago has now produced craniofacial portions of several hominid individuals, along with many well-preserved animal fossils and quantities of stone artifacts. Although there are certain anatomical differences among the

Abesalom Vekua; David Lordkipanidze; G. Philip Rightmire; Jordi Agusti; Reid Ferring; Givi Maisuradze; Alexander Mouskhelishvili; Medea Nioradze; Marcia Ponce de Leon; Martha Tappen; Merab Tvalchrelidze; Christoph Zollikofer

2002-01-01

172

Getting Into the Fossil Record  

NSDL National Science Digital Library

This computer activity provides a basic understanding of what a fossil is and the factors involved in becoming part of the fossil record. It is organized as an informational tour in two sections: one for middle school and one for high school. Students move at a self-selected pace by progressing and answering questions. A teacher's guide contains all necessary instructions as well as lesson plans, handouts, and assessment tools.

Jennifer Johnson

173

The legacy of fossil fuels.  

PubMed

Currently, over 80% of the energy used by mankind comes from fossil fuels. Harnessing coal, oil and gas, the energy resources contained in the store of our spaceship, Earth, has prompted a dramatic expansion in energy use and a substantial improvement in the quality of life of billions of individuals in some regions of the world. Powering our civilization with fossil fuels has been very convenient, but now we know that it entails severe consequences. We treat fossil fuels as a resource that anyone anywhere can extract and use in any fashion, and Earth's atmosphere, soil and oceans as a dump for their waste products, including more than 30?Gt/y of carbon dioxide. At present, environmental legacy rather than consistence of exploitable reserves, is the most dramatic problem posed by the relentless increase of fossil fuel global demand. Harmful effects on the environment and human health, usually not incorporated into the pricing of fossil fuels, include immediate and short-term impacts related to their discovery, extraction, transportation, distribution, and burning as well as climate change that are spread over time to future generations or over space to the entire planet. In this essay, several aspects of the fossil fuel legacy are discussed, such as alteration of the carbon cycle, carbon dioxide rise and its measurement, greenhouse effect, anthropogenic climate change, air pollution and human health, geoengineering proposals, land and water degradation, economic problems, indirect effects on the society, and the urgent need of regulatory efforts and related actions to promote a gradual transition out of the fossil fuel era. While manufacturing sustainable solar fuels appears to be a longer-time perspective, alternatives energy sources already exist that have the potential to replace fossil fuels as feedstocks for electricity production. PMID:21290608

Armaroli, Nicola; Balzani, Vincenzo

2011-03-01

174

Lipin proteins form homo- and hetero-oligomers  

PubMed Central

SUMMARY Lipin family members (lipin 1, 2, 3) are bi-functional proteins that dephosphorylate phosphatidic acid (PA) to produce diacylglycerol (DAG) and act in the nucleus to regulate gene expression. Although other components of the triglyceride synthesis pathway can form oligomeric complexes, it is unknown whether lipin proteins also exist as oligomers. In this study, by using various approaches, we revealed that lipin 1 formed stable homo-oligomers with itself and hetero-oligomers with lipin 2/3. Both the N- and C-terminal regions of lipin 1 mediate its oligomerization in a head-to-head/tail-to-tail manner. We also show that lipin 1 subcellular localization can be influenced through oligomerization, and the individual lipin 1 monomers in the oligomer function independently in catalyzing dephosphorylation of PA. This study provides evidence that lipin proteins function as oligomeric complexes and that the three mammalian lipin isoforms can form combinatorial units. PMID:20735359

Liu, Guang-Hui; Qu, Jing; Carmack, Anne E.; Kim, Hyun Bae; Chen, Chang; Ren, Hongmei; Morris, Andrew J.; Finck, Brian N.; Harris, Thurl E.

2011-01-01

175

STRUCTURES INTERNES CLAVICULAIRES CHEZ PAN, GORILLA ET HOMO. MTHODE D'ANALYSE ET RSULTATS PRLIMINAIRES  

E-print Network

STRUCTURES INTERNES CLAVICULAIRES CHEZ PAN, GORILLA ET HOMO. MÃ?THODE D'ANALYSE ET RÃ?SULTATS PRÃ?LIMINAIRES INTERNAL STRUCTURES OF THE CLAVICLE IN PAN, GORILLA AND HOMO. METHOD OF ANALYSIS AND PRELIMINARY density bone structure superior to that of gorillas and humans. For a quarter of chimpanzees

Paris-Sud XI, Université de

176

Technology Treaties and Fossil-Fuels Extraction  

Microsoft Academic Search

We consider some unintended effects of a technology treaty to increase the (stochastic) possibility of developing an energy alternative to fossil fuels which, when available, makes fossil fuels redundant. One implication of such a treaty is to increase the incentives for fossil-fuels producers to extract fossil fuels existing in given quantity more rapidly, under competition when the equilibrium price path

Jon Strand

2007-01-01

177

Travels with the Fossil Hunters  

NASA Astrophysics Data System (ADS)

Whether dodging bullets in West Africa, or rabid dogs in Pakistan, surviving yak-butter tea in Tibet, or eating raw fish in China, the life of a globe-trotting fossil hunter is often hazardous and always filled with surprises. Travels with the Fossil Hunters lets readers share the wonder, joys of discovery, and excitement of these intrepid scientists. Packed with more than 100 beautiful, full-color photographs, the volume takes readers on twelve expeditions to remote parts of the world in search of diverse fossil remains, from those of dinosaurs to human ancestors. Each expedition by paleontologists from London's Natural History Museum reveals the problems and challenges of working in extreme conditions, from the deserts of the Sahara and Yemen to the frozen wastes of Antarctica, from the mountains of India to the forests of Latvia. Along the way they also describe the paleontology and geology of the countries they visit and the scientific reasons for their expeditions. With a foreword from Sir David Attenborough and an introduction from Richard Fortey, this fascinating book will appeal to amateur and professional fossil hunters alike and to readers interested in accounts of exotic locales. Peter Whybrow is a research scientist at the Natural History Museum, London. His research interests include Arabian Miocene vertebrates, paleoclimates, paleogeography, and biotic diversity. He is senior editor with A. Hill of Fossil Vertebrates of Arabia (Yale University Press, New Haven, 1999).

Whybrow, Peter J.

2000-04-01

178

A Galactic Fossil  

NASA Astrophysics Data System (ADS)

How old are the oldest stars? Using ESO's VLT, astronomers recently measured the age of a star located in our Galaxy. The star, a real fossil, is found to be 13.2 billion years old, not very far from the 13.7 billion years age of the Universe. The star, HE 1523-0901, was clearly born at the dawn of time. "Surprisingly, it is very hard to pin down the age of a star", the lead author of the paper reporting the results, Anna Frebel, explains. "This requires measuring very precisely the abundance of the radioactive elements thorium or uranium, a feat only the largest telescopes such as ESO's VLT can achieve." ESO PR Photo 23a/07 ESO PR Photo 23a/07 The 'Cosmic Clock' This technique is analogous to the carbon-14 dating method that has been so successful in archaeology over time spans of up to a few tens of thousands of years. In astronomy, however, this technique must obviously be applied to vastly longer timescales. For the method to work well, the right choice of radioactive isotope is critical. Unlike other, stable elements that formed at the same time, the abundance of a radioactive (unstable) isotope decreases all the time. The faster the decay, the less there will be left of the radioactive isotope after a certain time, so the greater will be the abundance difference when compared to a stable isotope, and the more accurate is the resulting age. Yet, for the clock to remain useful, the radioactive element must not decay too fast - there must still be enough left of it to allow an accurate measurement, even after several billion years. "Actual age measurements are restricted to the very rare objects that display huge amounts of the radioactive elements thorium or uranium," says Norbert Christlieb, co-author of the report. ESO PR Photo 23b/07 ESO PR Photo 23b/07 Uranium Line in the Spectrum of an Old Star Large amounts of these elements have been found in the star HE 1523-0901, an old, relatively bright star that was discovered within the Hamburg/ESO survey [1]. The star was then observed with UVES on the Very Large Telescope (VLT) for a total of 7.5 hours. A high quality spectrum was obtained that could never have been achieved without the combination of the large collecting power Kueyen, one of the individual 8.2-m Unit Telescopes of the VLT, and the extremely good sensitivity of UVES in the ultraviolet spectral region, where the lines from the elements are observed. For the first time, the age dating involved both radioactive elements in combination with the three other neutron-capture elements europium, osmium, and iridium. "Until now, it has not been possible to measure more than a single cosmic clock for a star. Now, however, we have managed to make six measurements in this one star", says Frebel. Ever since the star was born, these "clocks" have ticked away over the eons, unaffected by the turbulent history of the Milky Way. They now read 13.2 billion years. The Universe being 13.7 billion years old, this star clearly formed very early in the life of our own Galaxy, which must also formed very soon after the Big Bang. More Information This research is reported in a paper published in the 10 May issue of the Astrophysical Journal ("Discovery of HE 1523-0901, a Strongly r-Process Enhanced Metal-Poor Star with Detected Uranium", by A. Frebel et al.). The team includes Anna Frebel (McDonald Observatory, Texas) and John E. Norris (The Australian National University), Norbert Christlieb (Uppsala University, Sweden, and Hamburg Observatory, Germany), Christopher Thom (University of Chicago, USA, and Swinburne University of Technlogy, Australia), Timothy C. Beers (Michigan State University, USA), Jaehyon Rhee (Center for Space Astrophysics, Yonsei University, Korea, and Caltech, USA).

2007-05-01

179

Fossil Groups as Cosmological Labs  

NASA Astrophysics Data System (ADS)

Optical and X-ray measurements of fossil groups (FGs) suggest that they are old and relaxed systems. If FGs are assembled at higher redshift, there is enough time for intermediate-luminosity galaxies to merge, resulting in the formation of the brightest group galaxy (BGG). We carry out the first, systematic study of a large sample of FGs, the "FOssil Group Origins'' (FOGO) based on an International Time Project at the Roque de los Muchachos Observatory. For ten FOGO FGs we have been awarded time at SUZAKU Telescope to measure the temperature of the hot intragroup gas (IGM). For these systems we plan to evaluate and correlate their X-ray luminosity and X-ray temperature, Lx-Tx, optical luminosity and X-ray temperature, Lopt-Tx, and group velocity dispersion with their X-ray temperature, sigma V-Tx, as compared to the non fossil systems. By combining these observations with state-of-art cosmological hydrodynamical simulations we will open a new window into the study of the IGM and the nature of fossil systems. Our proposed work will be of direct relevance for the understanding and interpretation of data from several NASA science missions. Specifically, the scaling relations obtained from these data combined with our predictions obtained using state-of-the-art hydrodynamical simulation numerical adopting a new hydrodynamical scheme will motivate new proposal on CHANDRA X-ray telescope for fossil groups and clusters. We will additionally create a public Online Planetarium Show. This will be an educational site, containing an interactive program called: "A Voyage to our Universe''. In the show we will provide observed images of fossil groups and similar images and movies obtained from the numerical simulations showing their evolution. The online planetarium show will be a useful reference and an interactive educational tool for both students and the public.

D'Onghia, Elena

180

Fossils: Observing, Making and Learning  

NSDL National Science Digital Library

In this activity, learners explore how casts of fossilized bones are created and used to learn about dinosaurs. Learners make observations, draw diagrams and share their findings. Learners also make clay molds to create plaster copies of real fossils. Then, learners consider how animals' and dinosaurs' body parts were used for protection, hunting, eating, etc. This activity is featured on pp.11-13 (part of a lesson that begins on p.7) of the "Dinosphere" unit of study for grades 3-5.

Rick Crosslin

2004-01-01

181

Observe how fossils can form  

NSDL National Science Digital Library

This Earth science animation demonstrates the formation of a cast and mold fossil to middle and high school students. The introduction provides a brief description of the process. The animation shows how a shelled animal becomes buried in mud that eventually turns into stone. The shell dissolves and is replaced by minerals and, when the layers of rock are split, a cast and mold fossil is revealed. Movie controls allow students to repeat, pause, or step through the animation, which can give students more time to analyze the images. Copyright 2005 Eisenhower National Clearinghouse

TERC. Center for Earth and Space Science Education

2003-01-01

182

FOSSIL2 energy policy model documentation: FOSSIL2 documentation  

SciTech Connect

This report discusses the structure, derivations, assumptions, and mathematical formulation of the FOSSIL2 model. Each major facet of the model - supply/demand interactions, industry financing, and production - has been designed to parallel closely the actual cause/effect relationships determining the behavior of the United States energy system. The data base for the FOSSIL2 program is large, as is appropriate for a system dynamics simulation model. When possible, all data were obtained from sources well known to experts in the energy field. Cost and resource estimates are based on DOE data whenever possible. This report presents the FOSSIL2 model at several levels. Volumes II and III of this report list the equations that comprise the FOSSIL2 model, along with variable definitions and a cross-reference list of the model variables. Volume II provides the model equations with each of their variables defined, while Volume III lists the equations, and a one line definition for equations, in a shorter, more readable format.

None

1980-10-01

183

An investigation of the HOMO electron density distribution of cyclopentene by electron momentum spectroscopy  

NASA Astrophysics Data System (ADS)

The highest occupied molecular orbital (HOMO) of cyclopentene (C 5H 8) has been studied by a binary (e, 2e) electron momentum spectroscopy, at an impact energy of 1200 eV plus the binding energy and using symmetric non-coplanar kinematics. The first measurements of the complete valence shell binding energy spectra and the HOMO momentum profile are reported. The experimental momentum profile of HOMO is compared with the theoretical momentum profiles calculated using Hartree-Fock and density functional theory method with various basis sets. The EMS experimental result is well described by the calculations.

Ren, X. G.; Ning, C. G.; Deng, J. K.; Zhang, S. F.; Su, G. L.; Zhou, H.; Li, B.; Li, G. Q.

2004-10-01

184

Geology Fieldnotes: Fossil Butte National Monument, Wyoming  

NSDL National Science Digital Library

Fossil Butte National Monument preserves a 50-million year old bed of Eocene limestone that contains one of the richest fossil deposits in the world. Site features include park geology information, photographs of fossils, related links, visitor information, multimedia resources, and resources for teaching geology with National Park examples. The park geology section discusses the Monument's geologic history and fossil beds, focusing on the conditions that created the fossil-rich region and on the history of fossil collection in the area. A map of the Monument is also included.

185

Evolution and the Fossil Record  

E-print Network

.) · Charles Darwin, 1859: The Origin of Species by Natural Selection. #12;Artificial Selection vs. Natural population growth #12;Charles Darwin in 1837, age 28, after voyage of the Beagle #12;Age 40 Age 45 #12;DarwinEvolution and the Fossil Record #12;The Study of Evolution · Two domains: the present and the past

Kammer, Thomas

186

Evolution and the Fossil Record  

E-print Network

of evolutionary change. (The other mechanism, a destructive force, is mass extinction.) · Charles Darwin, 1859;Charles Darwin in 1837, age 28, after voyage of the HMS Beagle #12;Age 40 Age 45 #12;Darwin in 1879, ageEvolution and the Fossil Record #12;The Study of Evolution · Two domains: the present and the past

Kammer, Thomas

187

Fossil/modern mole phylogeny  

NSDL National Science Digital Library

This study is introduced at the beginning of class, and runs throughout the quarter. Students are first given a paper describing a morphological phylogeny of modern moles. The first few weeks' labs teach the students basic phylogenetic methods and the aspects of skeletal morphology needed to understand the character descriptions. Students in groups of 2 or 3 are assigned a set of characters from a particular region of the skeleton (i.e. humerus, lower teeth, skull, etc.). Those groups are responsible for learning to distinguish those characters on a representative group of modern specimens (for which the character codings are already available in the paper they have) and then coding those characters for a number of fossil taxa. The fossils are either described in papers posted on the course website or are represented by specimens held in the instructor's research lab. Students are responsible for finding time to come in and work with the specimens. The next to last lab of the quarter is concerned with analyzing data within each group, for the class as a whole, for fossil taxa alone, and for fossil and modern taxa. Students then write up the results of their analyses for their term project due at the end of the quarter.

188

Synthetic soup ground trace fossils  

NSDL National Science Digital Library

This is a lab exercise where students make synthetic trace fossils (using fishing lures) that was presented as a scientific study: BIOGENIC SEDIMENTARY STRUCTURES PRODUCED BY WORMS IN SOUPY, SOFT MUDS: OBSERVATIONS FROM THE CHATTANOOGA SHALE (UPPER DEVONIAN) AND EXPERIMENTS, by VADEC LOBZA AND JURGEN SCHIEBER, JOURNAL OF SEDIMENTARY RESEARCH, VOL. 69, NO. 5, SEPTEMBER, 1999, P. 1041â1049

Clint Cowan

189

Biodiversity of the Fossil Record  

E-print Network

;Articulate Brachiopods #12;Mollusca #12;Mollusca: Class Bivalvia #12;Miocene marine bivalve, Maryland #12;Phylum Mollusca: Class Gastropoda #12;Nautilus, a cephalopod (Mollusca) #12;"Thing" examines a fossil nautiloid #12;Phylum Mollusca, Class Cephaplopoda, a goniatitic ammonoid #12;Phylum Mollusca, Class

Kammer, Thomas

190

Biodiversity of the Fossil Record  

E-print Network

Inarticulate Brachiopods #12;Articulate Brachiopods #12;Mollusca #12;Mollusca: Class Bivalvia #12;Miocene marine bivalve, Maryland #12;Phylum Mollusca: Class Gastropoda #12;Nautilus, a cephalopod (Mollusca) #12;"Thing" examines a fossil nautiloid #12;Phylum Mollusca, Class Cephaplopoda, a goniatitic ammonoid #12

Kammer, Thomas

191

Plant Fossils in the Laboratory  

NSDL National Science Digital Library

This exercise can be used to familiarize students and give them hands-on experience with plant fossils as well as sharpen their powers of observation. It may also be used to bring together interdisciplinary topics relating past events to present day issues.

Kisten P. Giebel (Virginia Commonwealth University;)

1981-06-07

192

Progress of fossil fuel science  

SciTech Connect

Coal is the most abundant and widely distributed fossil fuel. More than 45% of the world's electricity is generated from coal, and it is the major fuel for generating electricity worldwide. The known coal reserves in the world are enough for more than 215 years of consumption, while the known oil reserves are only about 39 times of the world's consumption and the known natural gas reserves are about 63 times of the world's consumption level in 1998. In recent years, there have been effective scientific investigations on Turkish fossil fuels, which are considerable focused on coal resources. Coal is a major fossil fuel source for Turkey. Turkish coal consumption has been stable over the past decade and currently accounts for about 24% of the country's total energy consumption. Lignite coal has had the biggest share in total fossil fuel production, at 43%, in Turkey. Turkish researchers may investigate ten broad pathways of coal species upgrading, such as desulfurization and oxydesulfurization, pyrolysis and hydropyrolysis, liquefaction and hydroliquefaction, extraction and supercritical fluid extraction, gasification, oxidation, briquetting, flotation, and structure identification.

Demirbas, M.F.

2007-07-01

193

Fossil Identification and Classification Lab  

NSDL National Science Digital Library

Students pick, sort, box, and identify fossils (mostly mollusks but also bryozoa, arthropods, cnidaria, and annelids) from richly fossiliferous, clastic marine sediment, compile a faunal list,compare the fauna with modern taxa, and make evaluate a paleogeographic model for the taxa found.

Ralph Willoughby

194

Hagerman Fossil Beds National Monument  

NSDL National Science Digital Library

This National Park Service website offers descriptions of: the animal fossils found at this park, including the extinct Hagerman horse; the geology of the park which is mostly floodplain sediments of primarily silty clays; and the geological, hydrological, and hydrostratigraphical aspects of a landslide model. There are photos of park landslides, prehistoric projectile points, and the historical Oregon Trail.

195

Theory of fossil magnetic field  

NASA Astrophysics Data System (ADS)

Theory of fossil magnetic field is based on the observations, analytical estimations and numerical simulations of magnetic flux evolution during star formation in the magnetized cores of molecular clouds. Basic goals, main features of the theory and manifestations of MHD effects in young stellar objects are discussed.

Dudorov, Alexander E.; Khaibrakhmanov, Sergey A.

2015-02-01

196

The Oklo Fossil Fission Reactors  

NSDL National Science Digital Library

This web page gives an overview of the Oklo Fossil Fission Reactors, including the history of the area where the reactor is located, the science behind the nuclear reactions, and reasons for studying this nuclear reactor. This page also includes graphics describing the Physics behind the reactors, maps, and pictures of the reactor.

Loss, Robert

2012-06-15

197

Fossil Energy: Drivers and Challenges.  

NASA Astrophysics Data System (ADS)

Concerns about rapid economic growth, energy security, and global climate change have created a new landscape for fossil energy exploration, production, and utilization. Since 85% of primary energy supply comes from fossil fuels, and 85% of greenhouse gas emissions come from fossil fuel consumption, new and difficult technical and political challenges confront commercial, governmental, and public stakeholders. As such, concerns over climate change are explicitly weighed against security of international and domestic energy supplies, with economic premiums paid for either or both. Efficiency improvements, fuel conservation, and deployment of nuclear and renewable supplies will help both concerns, but are unlikely to offset growth in the coming decades. As such, new technologies and undertakings must both provide high quality fossil energy with minimal environmental impacts. The largest and most difficult of these undertakings is carbon management, wherein CO2 emissions are sequestered indefinitely at substantial incremental cost. Geological formations provide both high confidence and high capacity for CO2 storage, but present scientific and technical challenges. Oil and gas supply can be partially sustained and replaced through exploitation of unconventional fossil fuels such as tar-sands, methane hydrates, coal-to-liquids, and oil shales. These fuels provide enormous reserves that can be exploited at current costs, but generally require substantial energy to process. In most cases, the energy return on investment (EROI) is dropping, and unconventional fuels are generally more carbon intensive than conventional, presenting additional carbon management challenges. Ultimately, a large and sustained science and technology program akin to the Apollo project will be needed to address these concerns. Unfortunately, real funding in energy research has dropped dramatically (75%) in the past three decades, and novel designs in fission and fusion are not likely to provide any substantial offset in the next 30 years when they are most needed internationally.

Friedmann, Julio

2007-04-01

198

ConcepTest: Best Index Fossil  

NSDL National Science Digital Library

Four outcrops of rock are examined in different locations of a state. The rock types and the fossils they contain are illustrated in the adjacent diagram. Which fossil would be the best choice to use as an index ...

199

A Biological Time Capsule. Fossil Fish.  

ERIC Educational Resources Information Center

Described is an activity where students prepare high-quality fossil specimens to demonstrate the theory of evolution. The technique needed for fossil removal, the geologic and paleoclimatic setting, and the fish morphology are discussed. (KR)

Dolph, Gary E.; Dolph, Laura L.

1990-01-01

200

Identifying Fossils: Exploring the Mississippi River Bluffs  

NSDL National Science Digital Library

This activity is a geology lab where students learn about fossils found in sedimentary rocks and show their understanding by writing a literary nonfiction paper from the perspective of one of those fossils.

201

A New Kind of Economy is Born - Social Decision-Makers Beat the "Homo Economicus"  

E-print Network

The Internet and Social Media change our way of decision-making. We are no longer the independent decision makers we used to be. Instead, we have become networked minds, social decision-makers, more than ever before. This has several fundamental implications. First of all, our economic theories must change, and second, our economic institutions must be adapted to support the social decision-maker, the "homo socialis", rather than tailored to the perfect egoist, known as "homo economicus".

Helbing, Dirk

2013-01-01

202

An ecomorphological model of the initial hominid dispersal from Africa.  

PubMed

We use new data on the timing and extent of the early Pleistocene dispersal of Homo erectus to estimate diffusion coefficients of early Homo from Africa. These diffusion coefficients indicate more rapid and efficient dispersals than those calculated for fossil Macaca sp., Theropithecus darti, and Mesopithecus pentelicus. Increases in home range size associated with changes in ecology, hominid body size, and possibly foraging strategy may underlay these differences in dispersal efficiency. Ecological data for extant primates and human foragers indicate a close relationship between body size, home range size, and diet quality. These data predict that evolutionary changes in body size and foraging behavior would have produced a 10-fold increase in the home range size of H. erectus compared with that of the australopithecines. These two independent datasets provide a means of quantifying aspects of the dispersal of early Homo and suggest that rapid rates of dispersal appear to have been promoted by changes in foraging strategy and body size in H. erectus facilitated by changes in ecosystem structure during the Plio-Pleistocene. PMID:12473483

Antón, S C; Leonard, W R; Robertson, M L

2002-12-01

203

The oldest fossil myxogastroid slime mould.  

PubMed

A piece of Baltic amber (Tertiary, Eocene) contains a sporocarp of a slime mould which is assigned to the recent genus Arcyria and described as A. sulcata sp. nov. Apart from a fossil stemonitoid myxomycete, there are no further unambiguous fossil records of slime moulds and therefore the fossil gives new insights into the evolutionary history of the Myxomycetes. PMID:12735253

Dörfelt, Heinrich; Schmidt, Alexander R; Ullmann, Peter; Wunderlich, Jörg

2003-01-01

204

Cretaceous Fossils: Plants Quick Identification Gallery  

NSDL National Science Digital Library

This site forms a component of the CretaceousFossils.com page providing detailed information and high resolution photos of Cretaceous plants. The site supplies a practical, visual resource designed to facilitate identification of plant fossils from the Cretaceous Period. Educators and students alike may find this site and its links useful for viewing, identifying and downloading photos of exceptionally preserved fossil plant specimens.

Keith, Minor; Cretaceousfossils.com

205

004144:a0001 Fossil Record: Quality  

E-print Network

004144:a0001 Fossil Record: Quality Michael J Benton, University of Bristol, Bristol, UK There are divergent opinions about the quality of the fossil record and its ability to give a useful representation phylogenies, suggests that the fossils do tell the story relatively well. 004144:s0001 Introduction 004144:p

Benton, Michael

206

Fossils in Antarctica: British Antarctic Survey  

NSDL National Science Digital Library

Although marching penguins add to Antarctica's allure, The British Antarctic Survey (BAS) has found fossil evidence that dinosaurs, marsupials, and forests inhabited the area long before penguins charmed the world with their trademark waddle. Since 1940, when the fossil collection of the BAS was started, it has grown to 40,000 specimens. The "Fossils" section of the BAS website can be found on the left side of the homepage in the "About Antarctica" area, and is divided into two explanatory sections: "Fossils from the Antarctic" and "Fossil Locations in Antarctica". There are also links in each section, near the top right hand corner of the page, to "Type and Figured Fossil Collection" and "Fossils Picture Gallery". In the "Fossils from the Antarctic" section, the types of fossils found are explained and include: molluscs, arthropods, echinoderms and plants. The "Fossil Locations in Antarctica" section has a map of the three islands where a large amount of fossils have been found, along with descriptions of each island and what general types of fossils have been found on them.

207

Looking at Fossils in New Ways  

ERIC Educational Resources Information Center

Existing fossils could be studied from a different prospective with the use of new methods of analysis for gathering more information. The new techniques of studying fossils binds the new and the old techniques and information and provides another way to look at fossils.

Flannery, Maura C.

2005-01-01

208

Constraining fossil calibrations for molecular clocks  

E-print Network

Constraining fossil calibrations for molecular clocks Sir, In a recent paper, Mu¨ller and Reisz(1) proposed how fossil calibrations should be selected for application in molecular clock studies. The topic molecules. Nonetheless, we believe that these authors have erred both in their proposal of fossil

Kumar, Sudhir

209

Fossil: A Robust Relational Learner Johannes Furnkranz  

E-print Network

Fossil: A Robust Relational Learner Johannes F¨urnkranz juffi@ai.univie.ac.at Austrian Research in this paper describes Fossil, an ILP system that uses a search heuristic based on statistical correlation, Fossil's stopping criterion depends on a search heuristic that estimates the utility of literals

Fürnkranz, Johannes

210

Cycads: Fossil evidence of late paleozoic origin  

USGS Publications Warehouse

Plant fossils from Lower Permian strata of the southwestern United States have been interpreted as cycadalean megasporophylls. They are evidently descended from spermopterid elements of the Pennsylvanian Taeniopteris complex; thus the known fossil history of the cycads is extended from the Late Triassic into the late Paleozoic. Possible implications of the Permian fossils toward evolution of the angiosperm carpel are considered.

Mamay, S.H.

1969-01-01

211

Fossil fuel subsidies and environmental constraints  

Microsoft Academic Search

Fossil fuel subsidies are applied in many countries for different policy reasons such as maintaining jobs in fossil fuel sectors, securing national energy supply or lowering the energy costs of selected industries to strengthen competitiveness. The current economic costs of fossil fuel subsidy policies can be substantially increased by future environmental constraints. We illustrate this point in the framework of

Christoph Böhringer

1996-01-01

212

Atmospheric Lifetime of Fossil Fuel Carbon Dioxide  

E-print Network

Atmospheric Lifetime of Fossil Fuel Carbon Dioxide David Archer,1 Michael Eby,2 Victor Brovkin,3 released from combustion of fossil fuels equilibrates among the various carbon reservoirs of the atmosphere literature on the atmospheric lifetime of fossil fuel CO2 and its impact on climate, and we present initial

Scherer, Norbert F.

213

Science 101: What is a fossil?  

NSDL National Science Digital Library

A fossil is a preserved trace of an organism or event. There are many types of fossils.Usually these are preserved in sedimentary rocks--like sandstone, limestone, and shale--laid downon the surface of the planet or under its oceans. A paleontologist provides the basic facts about fossils.

Norell, Mark A.

2003-02-01

214

Fossil groups of galaxies: Are they groups? Are they fossils?  

NASA Astrophysics Data System (ADS)

Fossil groups present a puzzle to current theories of structure formation. Despite the low number of bright galaxies, their high velocity dispersions and high TX indicate cluster-like potential wells. Measured concentration parameters seem very high indicating early formation epochs in contradiction with the observed lack of large and well defined cooling cores. There are very few fossil groups with good quality X-ray data and their idiosyncrasies may enhance these apparent contradictions. The standard explanation for their formation suggests that bright galaxies within half the virial radii of these systems were wiped out by cannibalism forming the central galaxy. Since dry mergers, typically invoked to explain the formation of the central galaxies, are not expected to change the IGM energetics significantly, thus not preventing the formation of cooling cores, we investigate the scenario where recent gaseous (wet) mergers formed the central galaxy injecting energy and changing the chemistry of the IGM in fossil groups. We show a test for this scenario using fossil groups with enough X-ray flux in the Chandra X-ray Observatory archive by looking at individual metal abundance ratio distributions near the core. Secondary SN II powered winds would tend to erase the dominance of SN IA ejecta in the core of these systems and would help to erase previously existing cold cores. Strong SN II-powered galactic winds resulting from galaxy merging would be trapped by their deep potential wells reducing the central enhancement of SN Ia/SN II iron mass fraction ratio. The results indicate that there is a decrement in the ratio of SN Ia to SN II iron mass fraction in the central regions of the systems analyzed, varying from 99±1% in the outer regions to 85±2% within the cooling radius (Figure 1) and would inject enough energy into the IGM preventing central gas cooling. The results are consistent with a scenario of later formation epoch for fossil groups, as they are defined, when compared to galaxy clusters and normal groups.

Dupke, Renato de Alencar; Miller, Eric; de Oliveira, Claudia Mendes; Sodre, Laerte; Rykoff, Eli; de Oliveira, Raimundo Lopes; Proctor, Rob

2010-11-01

215

Fossil identification activity Standard: Comparing fossils to each other or to living organisms reveals features of  

E-print Network

Fossil identification activity Grade: 4th Standard: Comparing fossils to each other or to living. Instructions: This activity requires the fossil kit from the CSM museum. Create 8 stations, each station having one of the fossils from the list and a question sheet described below. Stations 1. Hesperocyon sp. XI6

216

The conservation and use of fossil vertebrate sites: British fossil reptile sites  

E-print Network

The conservation and use of fossil vertebrate sites: British fossil reptile sites Michael J. Benton and William A. Wimbledon BENTON. M. J. & W. A. WIMBLEDON. 19R5. The conservation and use of fossil vertebrate sites: British fossil reptile sites. Proc. Geol. Ass., 96 (I). 1-0. Over a thousand sites in Britain

Benton, Michael

217

FOSSIL SPRINGS ROADLESS AREA, ARIZONA.  

USGS Publications Warehouse

Based on field studies, the Fossil Springs Roadless Area in central Arizona is concluded to have little promise for the occurrence of mineral or energy resources. Rocks in the Supai Formation (Pennsylvanian-Permian) near the central part of the roadless area contain widespread but spotty copper mineralization and trace amounts of uranium. Analyses obtained during the study define geochemical anomalies in two portions of the area that remain unexplained. The suites of anomalous metals suggest the possibility of hydrothermal veins and the presence of ultramafic rocks; neither were found in the field. Although there is little promise for the occurrence of mineral resources in the Fossil Springs Roadless Area, studies to identify the source of the geochemical anomalies could have valuable implications for regional studies and mineral exploration in the surrounding area.

Beard, L.S.; Ellis, C.E.

1984-01-01

218

Clustering Fossils in Solid Inflation  

E-print Network

In solid inflation the single field non-Gaussianity consistency condition is violated. As a result, the long tensor perturbation induces observable clustering fossils in the form of quardupole anisotropy in large scale structure power spectrum. In this work we revisit the bispectrum analysis for the scalar-scalar-scalar and tensor-scalar-scalar for the general parameter space of solid. We consider the parameter space of the model in which the level of non-Gaussianity generated is consistent with Planck constraints. Specializing to this allowed range of model parameter, we calculate the quadrupole anisotropy induced from the long tensor perturbations on the power spectrum of scalar perturbations. We argue that imprints of clustering fossil from primordial gravitational waves on large scale structures can be detected from the future galaxy surveys.

Mohammad Akhshik

2014-09-10

219

Extinction and the fossil record  

NASA Technical Reports Server (NTRS)

The author examines evidence of mass extinctions in the fossil record and searches for reasons for such large extinctions. Five major mass extinctions eliminated at least 40 percent of animal genera in the oceans and from 65 to 95 percent of ocean species. Questions include the occurrence of gradual or catastrophic extinctions, causes, environment, the capacity of a perturbation to cause extinctions each time it happens, and the possibility and identification of complex events leading to a mass extinction.

Sepkoski, J. J. Jr; Sepkoski JJ, ,. J. r. (Principal Investigator)

1994-01-01

220

Fossil Collection and Museum Curation  

NSDL National Science Digital Library

Before we go into the field, students are exposed to field collection techniques and appropriate information to collect at the outcrop. This assignment is good for field trips because students each collect 1 or few samples, but spend time on the outcrop measuring a section and collecting associated lithologic and other fossil data if available (locality information, exposure, over and underlying sedimentology, details of host rock, sedimentary structures, assocaited fossils, diversity and abundance, taphonomic condition of fossils, etc). The field locality can be anywhere where there are resaonably well preserved fossils (and should give students an appreciation of museum quality specimens). This allows this exercise to be flexible as field trip localities change. All of the information that they collect in the field will be included in their field notebook that is handed in at the end of the field trip for evaluation. In the lab-I used class time-students are asked to make a detailed sketch of their sample that they can take to the library with them, and a discussion is held as to where to look for information to identify specimens with. Students are given a week (variable depending on the availability of resources, for example if monographs need to be aquired through inter-library loan) to idenitfy their specimen and then asked to catalog them for the museum. They fill out a SUNY Oswego Paleontology Museum card, which they have seen all semester for their sample and are given the option to donate it to the collection or keep it.

Boyer, Diana

221

Dinosaurs: Ancient Fossils, New Discoveries  

NSDL National Science Digital Library

This Web site, created to complement the Museum's Dinosaurs: Ancient Fossils, New Discoveries exhibit, offers a virtual visit to the Museum, complete with text, photos, video clips, audio interviews, and more and includes much of the information which was in the original exhibit which is now closed. The site includes information on the bio-mechanics of dinosaurs and the reasons behind some of their strange appearances.

222

A Facelift For Fossil Fuel  

Microsoft Academic Search

As scientists around the world scramble to develop a viable alternative to fossil fuels, one Wayne State researcher is working to improve the traditional oil refining process for a cleaner, more securely-obtained gasoline. Stephanie Brock, Ph.D., professor of chemistry in the College of Liberal Arts and Sciences, is working as a co-investigator with Mark Bussell, Ph.D., professor of chemistry at

Amy Oprean

2010-01-01

223

Evaluating developmental shape changes in Homo antecessor subadult facial morphology.  

PubMed

The fossil ATD6-69 from Atapuerca, Spain, dated to ca. 900 ka (thousands of years ago) has been suggested to mark the earliest appearance of modern human facial features. However, this specimen is a subadult and the interpretation of its morphology remains controversial, because it is unclear how developmental shape changes would affect the features that link ATD6-69 to modern humans. Here we analyze ATD6-69 in an evolutionary and developmental context. Our modern human sample comprises cross-sectional growth series from four populations. The fossil sample covers human specimens from the Pleistocene to the Upper Paleolithic, and includes several subadult Early Pleistocene humans and Neanderthals. We digitized landmarks and semilandmarks on surface and CT scans and analyzed the Procrustes shape coordinates using multivariate statistics. Ontogenetic allometric trajectories and developmental simulations were employed in order to identify growth patterns and to visualize potential adult shapes of ATD6-69. We show that facial differences between modern and archaic humans are not exclusively allometric. We find that while postnatal growth further accentuates the differences in facial features between Neanderthals and modern humans, those features that have been suggested to link ATD6-69's morphology to modern humans would not have been significantly altered in the course of subsequent development. In particular, the infraorbital depression on this specimen would have persisted into adulthood. However, many of the facial features that ATD6-69 shares with modern humans can be considered to be part of a generalized pattern of facial architecture. Our results present a complex picture regarding the polarity of facial features and demonstrate that some modern human-like facial morphology is intermittently present in Middle Pleistocene humans. We suggest that some of the facial features that characterize recent modern humans may have developed multiple times in human evolution. PMID:23998458

Freidline, Sarah E; Gunz, Philipp; Harvati, Katerina; Hublin, Jean-Jacques

2013-10-01

224

Scaling relations in fossil galaxy groups  

E-print Network

Using Chandra X-ray observations and optical imaging and spectroscopy of a flux-limited sample of 5 fossil groups, supplemented by additional systems from the literature, we provide the first detailed study of the scaling properties of fossils compared to normal groups and clusters. In general, all the fossils we study show regular and symmetric X-ray emission, indicating an absence of recent major group mergers. We confirm that, for a given optical luminosity of the group, fossils are more X-ray luminous than non-fossil groups. Fossils, however, fall comfortably on the conventional L_X-T_X relation of galaxy groups and clusters, suggesting that their X-ray luminosity and their gas temperature are both boosted, arguably, as a result of their early formation. This is supported by other scaling relations including the L_X-sigma and T_X-sigma relations in which fossils show higher X-ray luminosity and temperature for a given group velocity dispersion. We find that mass concentration in fossils is higher than in non-fossil groups and clusters. In addition, the M_X-T_X relation suggests that fossils are hotter, for a given total gravitational mass, both consistent with an early formation epoch for fossils. We show that the mass-to-light ratio in fossils is rather high but not exceptional, compared to galaxy groups and clusters. The entropy of the gas in low mass fossils appears to be systematically lower than that in normal groups, which may explain why the properties of fossils are more consistent with an extension of cluster properties. We conclude that the cuspy potential raises the luminosity and temperature of the IGM in fossils. However, this works in conjunction with lower gas entropy, which may arise from less effective preheating of the gas.

Habib G. Khosroshahi; Trevor J. Ponman; Laurence R. Jones

2007-02-04

225

Evolution and the Fossil Record  

NSDL National Science Digital Library

This publication of the American Geological Institute is a non-technical introduction to evolution and aims to help the general public gain a better understanding of one of the fundamental underlying concepts of modern science. Concepts covered include geologic time, change through time, Darwin's theory of evolution, evolution as a mechanism for change, the nature of species, the nature of theory, paleontology, and determination of age. Four case studies highlight examples of evolution from the fossil record to provide a perspective for understanding the evolution of life on Earth.

Dale Springer

2007-12-12

226

Dinosaur Fossils Predict Body Temperatures  

E-print Network

Perhaps the greatest mystery surrounding dinosaurs concerns whether they were endotherms, ectotherms, or some unique intermediate form. Here we present a model that yields estimates of dinosaur body temperature based on ontogenetic growth trajectories obtained from fossil bones. The model predicts that dinosaur body temperatures increased with body mass from approximately 25 8C at 12 kg to approximately 41 8C at 13,000 kg. The model also successfully predicts observed increases in body temperature with body mass for extant crocodiles. These results provide direct evidence that dinosaurs were reptiles that exhibited inertial homeothermy.

James F. Gillooly; Andrew P. Allen; Eric L. Charnov

227

Oldest Fossil Basidiomycete Clamp Connections  

E-print Network

of the family Polyporaceae (Hibbett et al. 1994), and suggested that the fossil was a saprotroph. The biological nature of the relationship between Botryopteris antiqua and the Visean clamp-bearing hyphae is difficult to determine because of the incompleteness... of both the host plant and fungus. The fungus could have been biotrophic or saprotrophic. If the conical callosities found in several of the cortical cells (Fig. 1m,n) formed in response to invading clamp-bearing hyphae, then this host response would favor...

Krings, Michael; Dotzler, Nora; Galtier, Jean; Taylor, Thomas N.

2011-01-01

228

Teaching Paleontology: Fascinating Fossils (title provided or enhanced by cataloger)  

NSDL National Science Digital Library

This National Park Service (NPS) educational website contains a presentation for upper-elementary students about fossils and how they form. Detailed photos and illustrations discuss fossil types such as petrification or permineralization, carbon fossils, trace fossils, casts and molds, pseudofossils and index fossils. This slide show indicates how these different fossil types form and are preserved, and in which National Park areas they are found. The parks mentioned included John Day Fossil Beds, Petrified Forest, Agate Fossil Beds, Florissant Fossil Beds, and Hagerman Fossil Beds.

Florissant Fossil Beds National Monument

1999-12-17

229

Fossil energy program. Summary document  

SciTech Connect

This program summary document presents a comprehensive overview of the research, development, and demonstration (RD and D) activities that will be performed in FY 1981 by the Assistant Secretary for Fossil Energy (ASFE), US Department of Energy (DOE). The ASFE technology programs for the fossil resources of coal, petroleum (including oil shale) and gas have been established with the goal of making substantive contributions to the nation's future supply and efficienty use of energy. On April 29, 1977, the Administration submitted to Congress the National Energy Plan (NEP) and accompanying legislative proposals designed to establish a coherent energy policy structure for the United States. Congress passed the National Energy Act (NEA) on October 15, 1978, which allows implementation of the vital parts of the NEP. The NEP was supplemented by additional energy policy statements culminating in the President's address on July 15, 1979, presenting a program to further reduce dependence on imported petroleum. The passage of the NEA-related energy programs represent specific steps by the Administration and Congress to reorganize, redirect, and clarify the role of the Federal Government in the formulation and execution of national energy policy and programs. The energy technology RD and D prog4rams carried out by ASFE are an important part of the Federal Government's effort to provide the combination and amounts of energy resources needed to ensure national security and continued economic growth.

None

1980-05-01

230

The fossil record of the Peronosporomycetes (Oomycota).  

PubMed

Evidence of fossil Peronosporomycetes has been slow to accumulate. In this review various fossils historically assigmed to the Peronosporomycets are dicussed briefly and an explanation is provided as to why the fossil record of this grouop has remained inconsistent. In recent year there has been several new reports of fossil peronosporomycetes based on structurally preserved oogonium-antheridium complexes from Derovonian and Carboniferous rocks that demonstrate the existence of these organisms as fossils and refute the long-standing assumption that they are too delicate to be preserved. Among these are serral tyoes characterized by oogonial surface members of the group. To date at last three groups of fossil vascular plants (i.e. lycophytes, ferns and seed ferns) are known to host peronosporomycetes aas endophytes; however only one form has been identified as a parasite. PMID:21289104

Krings, Michael; Taylor, Thomas N; Dotzler, Nora

2011-01-01

231

Layered Fossil Parfait: Deeper is Older  

NSDL National Science Digital Library

In this activity, learners explore dinosaur fossils by making an edible treat. First, learners read "Dinosaur Bones" by Aliki to examine how fossils are formed. Then, the educator sifts through the class garbage to demonstrate that the deeper something is buried the older it may be. Next, learners make a layered dinosaur fossil model using candy and other treats. This activity is featured on page 30 of the "Dinosphere" unit of study for K-2 learners.

2014-04-14

232

Fossilization Processes in Thermal Springs  

NASA Technical Reports Server (NTRS)

To create a comparative framework for the study of ancient examples, we have been carrying out parallel studies of the microbial biosedimentology, taphonomy and geochemistry of modem and sub-Recent thermal spring deposits. One goal of the research is the development of integrated litho- and taphofacies models for siliceous and travertline sinters. Thermal springs are regarded as important environments for the origin and early evolution of life on Earth, and we seek to utilize information from the fossil record to reconstruct the evolution of high temperature ecosystems. Microbial contributions to the fabric of thermal spring sinters occur when population growth rates keep pace with, or exceed rates of inorganic precipitation, allowing for the development of continuous biofilms or mats. In siliceous thermal springs, microorganisms are typically entombed while viable. Modes of preservation reflect the balance between rates of organic matter degradation, silica precipitation and secondary infilling. Subaerial sinters are initially quite porous and permeable and at temperatures higher than about 20 C, organic materials are usually degraded prior to secondary infilling of sinter frameworks. Thus, organically-preserved microfossils are rare and fossil information consists of characteristic biofabrics formed by the encrustation and underplating of microbial mat surfaces. This probably accounts for the typically low total organic carbon values observed in thermal spring deposits. In mid-temperature, (approx. 35 - 59 C) ponds and outflows, the surface morphology of tufted Phormidium mats is preserved through mat underplating by thin siliceous: crusts. Microbial taxes lead to clumping of ceils and/or preferred filament orientations that together define higher order composite fabrics in thermal spring stromatolites (e.g. network, coniform, and palisade). At lower temperatures (less than 35 C), Calothrix mats cover shallow terracette pools forming flat carpets or pustular surfaces that produce palisade and "shrub" fabrics, respectively. At finer scales, composite fabrics are seen to consist distinctive associations of microstructures formed by the encrustation of individual cells and filaments. Composite fabrics survive the diagenetic transitions from primary opaline silica to quartz and are known from subaerial thermal spring deposits as old as Lower Carboniferous. However, fossil microorganisms tend to be rare in older deposits, and are usually preserved only where cells or sheaths have been stained by iron oxides. In subaqueous mineralizing springs at lower temperatures, early infilling leads to a more rapid and complete reduction in porosity and permeability. This process, along with the slower rates of microbial degradation at lower temperatures, creates a more favorable situation for organic matter preservation. Application of this taphonomic model to the Rhynie Chert, previously interpreted as subaerial, suggest it was probably deposited in a subaqueous spring setting at lower temperatures.

Farmer, Jack D.; Cady, Sherry; Desmarais, David J.; Chang, Sherwood (Technical Monitor)

1995-01-01

233

The Omo-Turkana Basin fossil hominins and their contribution to our understanding of human evolution in Africa.  

PubMed

The Omo-Turkana Basin, including the hominin fossil sites around Lake Turkana and the sites along the lower reaches of the Omo River, has made and continues to make an important contribution to improving our murky understanding of human evolution. This review highlights the various ways the Omo-Turkana Basin fossil record has contributed to, and continues to challenge, interpretations of human evolution. Despite many diagrams that look suspiciously like comprehensive hypotheses about human evolutionary history, any sensible paleoanthropologist knows that the early hominin fossil record is too meager to do anything other than offer very provisional statements about hominin taxonomy and phylogeny. If history tells us anything, it is that we still have much to learn about the hominin clade. Thus, we summarize the current state of knowledge of the hominin species represented at the Omo-Turkana Basin sites. We then focus on three specific topics for which the fossil evidence is especially relevant: the origin and nature of Paranthropus; the origin and nature of early Homo; and the ongoing debate about whether the pattern of human evolution is more consistent with speciation by cladogenesis, with greater taxonomic diversity or with speciation by anagenetic transformation, resulting in less taxonomic diversity and a more linear interpretation of human evolutionary history. PMID:22170695

Wood, Bernard; Leakey, Meave

2011-01-01

234

Fossil diatoms and neogene paleolimnology  

USGS Publications Warehouse

Diatoms have played an important role in the development of Neogene continental biostratigraphy and paleolimnology since the mid-19th Century. The history of progress in Quaternary diatom biostratigraphy has developed as a result of improved coring techniques that enable sampling sediments beneath existing lakes coupled with improved chronological control (including radiometric dating and varve enumeration), improved statistical treatment of fossil diatom assemblages (from qualitative description to influx calculations of diatom numbers or volumes), and improved ecological information about analogous living diatom associations. The last factor, diatom ecology, is the most critical in many ways, but progresses slowly. Fortunately, statistical comparison of modern diatom assemblages and insightful studies of the nutrient requirements of some common freshwater species are enabling diatom paleolimnologists to make more detailed interpretations of the Quaternary record than had been possible earlier, and progress in the field of diatom biology and ecology will continue to refine paleolimnological studies. The greater age and geologic setting of Tertiary diatomaceous deposits has prompted their study in the contexts of geologic history, biochronology and evolution. The distribution of diatoms of marine affinities in continental deposits has given geologists insights about tectonism and sea-level change, and the distribution of distinctive (extinct?) diatoms has found utilization both in making stratigraphic correlations between outcrops of diatomaceous deposits and in various types of biochronological studies that involve dating deposits in different areas. A continental diatom biochronologic scheme will rely upon evolution, such as the appearance of new genera within a family, in combination with regional environmental changes that are responsible for the wide distribution of distinctive diatom species. The increased use of the scanning electron microscope for the detailed descriptions of fossil diatoms will provide the basis for making more accurate correlations and identifications, and the micromorphological detail for speculations about evolutionary relationships. ?? 1988.

Platt, Bradbury J.

1988-01-01

235

The First Fossil Record of Caecilian Amphibians  

Microsoft Academic Search

THREE groups of amphibians are living today-frogs, salamanders and caecilians. The fossil record of frogs and salamanders is relatively poor1,2, but representatives of most groups have been discovered. For the caecilians, however, no authentic fossils have been recognized, until now. We describe here a single diagnostic vertebra from the Palaeocene of Brazil.

Richard Estes; MARVALEE H. WAKE

1972-01-01

236

Creature Features - Showcase of Living Fossils  

NSDL National Science Digital Library

This activity is a side project that students work on through the organismal portion of a course in paleobiology/paleontology. Students present on the lifestyle, habitat, and behavior of "living fossil" groups. The activity ties the fossil record to the modern living world and allows students to engage with ideas of evolutionary stasis, taphonomy, and functional morphology.

Sunderlin, David

237

Accuracy of Fossils and Dating Methods  

NSDL National Science Digital Library

The issue-focused, peer-reviewed article asserts that fossil dating is accurate because the method follows strict scientific guidelines: the age of rocks around a fossil can be considered, mathematical calculations are used, the state of decay, carbon-14, and isotopes figure in calculations, and tree of life relationships often help sort the dates.

Michael Benton (University of Bristol, UK;)

2001-01-01

238

The original colours of fossil beetles  

PubMed Central

Structural colours, the most intense, reflective and pure colours in nature, are generated when light is scattered by complex nanostructures. Metallic structural colours are widespread among modern insects and can be preserved in their fossil counterparts, but it is unclear whether the colours have been altered during fossilization, and whether the absence of colours is always real. To resolve these issues, we investigated fossil beetles from five Cenozoic biotas. Metallic colours in these specimens are generated by an epicuticular multi-layer reflector; the fidelity of its preservation correlates with that of other key cuticular ultrastructures. Where these other ultrastructures are well preserved in non-metallic fossil specimens, we can infer that the original cuticle lacked a multi-layer reflector; its absence in the fossil is not a preservational artefact. Reconstructions of the original colours of the fossils based on the structure of the multi-layer reflector show that the preserved colours are offset systematically to longer wavelengths; this probably reflects alteration of the refractive index of the epicuticle during fossilization. These findings will allow the former presence, and original hue, of metallic structural colours to be identified in diverse fossil insects, thus providing critical evidence of the evolution of structural colour in this group. PMID:21957131

McNamara, Maria E.; Briggs, Derek E. G.; Orr, Patrick J.; Noh, Heeso; Cao, Hui

2012-01-01

239

The Microbial Origin of Fossil Fuels  

Microsoft Academic Search

The authors have investigated the genesis of fossil fuels and different kinds of sedimentary deposits by studying the structure of individual fossil compounds in order to deduce the structure of their precursors in living organisms. Analysis revealed unexpected similarities, specifically in the pattern of peaks in gas chromatograms in the Cââ to Cââ region. Thousands of samples taken from all

Guy Ourisson; Pierre Albrecht; Michel Rohmer

1984-01-01

240

Species-specific proteins in fossils  

NASA Astrophysics Data System (ADS)

With a solid-phase radioimmunoassay it has been possible to detect species-specific collagen and albumin in fossils as old as 1.9 million years. This technique may provide new data on the genetic relations of fossil species to each other and to living forms.

Lowenstein, Jerold M.

1980-07-01

241

HEMATITE AND CALCITE COATINGS ON FOSSIL VERTEBRATES  

Microsoft Academic Search

Hematite coatings are common on vertebrate fossils from Paleocene\\/Eocene paleosol deposits in the Bighorn Basin, Wyoming. In general, hematite coatings are found only on fossils and are limited to soils exhibiting hydromorphic features and moderate maturity. Pet- rographic and isotopic evidence suggests that hematite and micritic calcite formed at nearly the same time in a pedogenic environment, whereas sparry calcite

HUIMING BAO; PAUL L. KOCH; ROBERT P. HEPPLE

242

Potential for travertine formation: Fossil Creek, Arizona  

E-print Network

, *, Roderic A. Parnella a Department of Geology, Northern Arizona University, Flagstaff, AZ 86001, USA b RockyPotential for travertine formation: Fossil Creek, Arizona John Malusaa , Steven T. Overbyb from Fossil Springs in Central Arizona were conducted to predict changes in travertine deposition

243

The Fossil Record Noel A. Heim and Dana H. Geary  

E-print Network

II.9 The Fossil Record Noel A. Heim and Dana H. Geary OUTLINE 1. Fossilization and taphonomy 2. The nature of the fossil record 3. Marine diversity in the Phanerozoic 4. The value of the fossil record The fossil record documents the history of life over the course of the past 3.5 billion years, demonstrates

Heim, Noel A.

244

Implicit and Explicit Category Learning by Macaques (Macaca mulatta) and Humans (Homo sapiens)  

E-print Network

Implicit and Explicit Category Learning by Macaques (Macaca mulatta) and Humans (Homo sapiens) J theoretical perspective differentiates in humans an explicit, rule-based system of category learning from. Humans and macaques learned categories composed of sine-wave gratings that varied across trials in bar

Indiana University

245

ON THE CONCEPT OF (HOMO)MORPHISM : A KEY NOTION IN THE LEARNING OF ABSTRACT ALGEBRA  

E-print Network

ON THE CONCEPT OF (HOMO)MORPHISM : A KEY NOTION IN THE LEARNING OF ABSTRACT ALGEBRA Thomas Algebra more accessible. I. INTRODUCTION In our context, Abstract Algebra means the discipline devoted to the study of algebraic structures, according to the new paradigm established after the publication of van

Paris-Sud XI, Université de

246

Female Condition Influences Preferences for Sexual Dimorphism in Faces of Male Humans (Homo sapiens )  

Microsoft Academic Search

In some species, female condition correlates positively with preferences for male secondary sexual traits. Women's preferences for sexually dimorphic characteristics in male faces (facial masculinity) have recently been reported to covary with self-reported attractiveness. As women's attractiveness has been proposed to signal reproductive condition, the findings in human (Homo sapiens) and other species may reflect similar processes. The current study

I. S. Penton-Voak; A. C. Little; B. C. Jones; D. M. Burt; B. P. Tiddeman; D. I. Perrett

2003-01-01

247

Adaptive sex ratio variation in pre-industrial human (Homo sapiens) populations?  

E-print Network

Adaptive sex ratio variation in pre-industrial human (Homo sapiens) populations? Virpi Lummaa-20014 Turku, Finland Sex allocation theory predicts that in a population with a biased operational sex ratio (OSR), parents will increase their ¢tness by adjusting the sex ratio of their progeny towards

Lummaa, Virpi

248

The orthoconic antiferroelectric smectic liquid crystals and their engineering by doping with homo- and heterostructural compounds  

Microsoft Academic Search

The attempt of the engineering of modern liquid crystalline orhoconic antiferroelectric smectic material OAFLC with remarkable optical properties is reported. The high tilted anticlinic antiferroelectric parent mixtures were formulated and studied. Subsequently those parent mixtures were doped with homo- and heterostructural dopants with selected properties including a molecular shape, molecular dipole moment ? value and orientation and molecular conformation. The

W. Piecek; R. D?browski; P. Morawiak; M. ?urowska; L. Jaroszewicz

2012-01-01

249

Robinlin: A novel bioactive homo-monoterpene from Robinia pseudoacacia L. (Fabaceae)  

Microsoft Academic Search

A bioactivity-directed fractionation of the ethanolic extracts of Robinia pseudoacacia L. (Fabaceae) afforded robinlin (1), a novel homo-monoterpene. The structure of 1 was elucidated by spectral analyses of the parent compound as well as its derivatives; 1 showed strong bioactivity in the brine shrimp lethality test (BST).

Feifei Tian; Ching-Jer Chang; John B Grutzner; David E Nichols; Jerry L McLaughlin

2001-01-01

250

John Day Fossil Beds National Monument  

NSDL National Science Digital Library

This National Park Service website offers an education section which includes: programs for visiting school groups involving the geological and evolutionary processes of the park, working with fossil casts, and other fossil activities; a list of classroom materials to send for (some have cost) including a horse fossil study kit, a general fossil kit, a teacher packet, and a videotape on the paleontology work at the park and evolution of the horse; and a list of teacher workshops in Oregon. There are species lists for vertebrate and plant fossils, diagrams of the major geologic formations and illustrations of different paleobiomes, species lists for existing flora and fauna, and a fire management plan. Regional and park history is covered as well as the history of the Chinookan, Sahaptian, Shoshonean, and Salishan Indians of Eastern Oregon. There is also information for planning a visit to the park.

251

Atomic force microscopy of Precambrian microscopic fossils.  

PubMed

Atomic force microscopy (AFM) is a technique used routinely in material science to image substances at a submicron (including nm) scale. We apply this technique to analysis of the fine structure of organic-walled Precambrian fossils, microscopic sphaeromorph acritarchs (cysts of planktonic unicellular protists) permineralized in approximately 650-million-year-old cherts of the Chichkan Formation of southern Kazakhstan. AFM images, backed by laser-Raman spectroscopic analysis of individual specimens, demonstrate that the walls of these petrified fossils are composed of stacked arrays of approximately 200-nm-sized angular platelets of polycyclic aromatic kerogen. Together, AFM and laser-Raman spectroscopy provide means by which to elucidate the submicron-scale structure of individual microscopic fossils, investigate the geochemical maturation of ancient organic matter, and, potentially, distinguish true fossils from pseudofossils and probe the mechanisms of fossil preservation by silica permineralization. PMID:12089337

Kempe, André; Schopf, J William; Altermann, Wladyslaw; Kudryavtsev, Anatoliy B; Heckl, Wolfgang M

2002-07-01

252

Atomic force microscopy of Precambrian microscopic fossils  

PubMed Central

Atomic force microscopy (AFM) is a technique used routinely in material science to image substances at a submicron (including nm) scale. We apply this technique to analysis of the fine structure of organic-walled Precambrian fossils, microscopic sphaeromorph acritarchs (cysts of planktonic unicellular protists) permineralized in ?650-million-year-old cherts of the Chichkan Formation of southern Kazakhstan. AFM images, backed by laser-Raman spectroscopic analysis of individual specimens, demonstrate that the walls of these petrified fossils are composed of stacked arrays of ?200-nm-sized angular platelets of polycyclic aromatic kerogen. Together, AFM and laser-Raman spectroscopy provide means by which to elucidate the submicron-scale structure of individual microscopic fossils, investigate the geochemical maturation of ancient organic matter, and, potentially, distinguish true fossils from pseudofossils and probe the mechanisms of fossil preservation by silica permineralization. PMID:12089337

Kempe, André; Schopf, J. William; Altermann, Wladyslaw; Kudryavtsev, Anatoliy B.; Heckl, Wolfgang M.

2002-01-01

253

Quaternary fossil fish from the Kibish Formation, Omo Valley, Ethiopia.  

PubMed

The late Quaternary Kibish Formation of the Omo Valley, southwestern Ethiopia, preserves environments reflecting a history of fluctuations in the level of nearby Lake Turkana over the past 200,000 years. The Kibish Formation has yielded a diverse mammalian fauna (as well as birds and crocodiles), stone tools, and the oldest anatomically modern Homo sapiens. Fish, the most common vertebrate fossils in this unit, are reported in this study. Catfish (especially clariids and Synodontis) and Nile perch (Lates niloticus) predominate, but the gymnarchid Gymnarchus, a cyprinid (Barbus), tigerfish (Hydrocynus), pufferfish (Tetraodon), and other catfish are also present. In total, nine teleost genera are found in the Kibish Formation, representing a subset of the 37 genera that constitute the modern Omo-Turkana ichthyofauna. Several taxa present in the modern fauna, including Polypterus and members of the family Cichlidae, are not found in the Kibish deposits. Most specimens are preserved as disarticulated or broken skeletal elements, but some preservation of articulated elements (e.g., sets of vertebrae, crania with lower jaws or cleithra) also occurs. Many of the catfish and Nile perch specimens are larger than the largest reported from the modern river or lake. Faunas of Kibish Members I and III closely resemble one another; the fauna from Member IV contains only the three most common taxa (Clarias, Synodontis, Lates), though this may result from insufficient sampling. Barbed bone points have been collected from the upper part of the formation, indicating a long association between the human inhabitants and the fish fauna of the Omo Valley. PMID:18691738

Trapani, Josh

2008-09-01

254

Clean Fossil Energy Conversion Processes  

NASA Astrophysics Data System (ADS)

Absolute and per-capita energy consumption is bound to increase globally, leading to a projected increase in energy requirements of 50% by 2020. The primary source for providing a majority of the energy will continue to be fossil fuels. However, an array of enabling technologies needs to be proven for the realization of a zero emission power, fuel or chemical plants in the near future. Opportunities to develop new processes, driven by the regulatory requirements for the reduction or elimination of gaseous and particulate pollutant abound. This presentation describes the chemistry, reaction mechanisms, reactor design, system engineering, economics, and regulations that surround the utilization of clean coal energy. The presentation will cover the salient features of the fundamental and process aspects of the clean coal technologies in practice as well as in development. These technologies include those for the cleaning of SO2, H2S, NOx, and heavy metals, and separation of CO2 from the flue gas or the syngas. Further, new combustion and gasification processes based on the chemical looping concepts will be illustrated in the context of the looping particle design, process heat integration, energy conversion efficiency, and economics.

Fan, L.-S.

2007-03-01

255

Systematics of some enigmatic "fossils"  

NSDL National Science Digital Library

Students are given sets of different shaped fasteners (staples, paper clips, tacks, etc.) and work with the instructor through a guided exercise in which they construct a character matrix and cladogram depicting the phylogeny of the "organisms". Students are then divided into small groups; each group receives a set of various shapes/colors of pasta. (The sets are all the same.) Each group must decide how many species are present in their sample (considering the potential for ontogenetic and sexual variation within species), choose and define characters for a cladistic analysis, and construct a character matrix. The instructor runs the matrices through cladistic analysis software, and the following week the students receive the results from analysis of each group's data. The class then discusses the effects of species definition, character choice, etc. on phylogenetic hypotheses. The activity allows students to directly confront issues of identifying and distinguishing morphological species. Conflicting results obtained by different groups analyzing the same data set drive home the complicated nature of character choice and definition in construction of a character matrix for cladistic analysis, and underscore the fact that individual cladograms represent phylogenetic hypotheses subject to modification by further analysis. (This last point becomes necessary background as students encounter different/competing hypotheses of phylogenetic relationships during study of fossil invertebrates.)

Allison Tumarkin-Deratzian

256

Summary statistics for fossil spider species taxonomy  

PubMed Central

Abstract Spiders (Araneae) are one of the most species-rich orders on Earth today, and also have one of the longest geological records of any terrestrial animal groups, as demonstrated by their extensive fossil record. There are currently around 1150 described fossil spider species, representing 2.6% of all described spiders (i.e. extinct and extant). Data for numbers of fossil and living spider taxa described annually (and various other metrics for the fossil taxa) were compiled from current taxonomic catalogues. Data for extant taxa showed a steady linear increase of approximately 500 new species per year over the last decade, reflecting a rather constant research activity in this area by a large number of scientists, which can be expected to continue. The results for fossil species were very different, with peaks of new species descriptions followed by long troughs, indicating minimal new published research activity for most years. This pattern is indicative of short bursts of research by a limited number of authors. Given the frequent discovery of new fossil deposits containing spiders, a wealth of new material coming to light from previously worked deposits, and the application of new imaging techniques in palaeoarachnology that allow us to extract additional data from historical specimens, e.g. X-ray computed tomography, it is important not only to ensure a sustained research activity on fossil spiders (and other arachnids) through training and enthusing the next generation of palaeoarachnologists, but preferably to promote increased research and expertise in this field. PMID:22639535

Penney, David; Dunlop, Jason A.; Marusik, Yuri M.

2012-01-01

257

Fossil oak galls preserve ancient multitrophic interactions  

PubMed Central

Trace fossils of insect feeding have contributed substantially to our understanding of the evolution of insect–plant interactions. The most complex phenotypes of herbivory are galls, whose diagnostic morphologies often allow the identification of the gall inducer. Although fossil insect-induced galls over 300?Myr old are known, most are two-dimensional impressions lacking adequate morphological detail either for the precise identification of the causer or for detection of the communities of specialist parasitoids and inquilines inhabiting modern plant galls. Here, we describe the first evidence for such multitrophic associations in Pleistocene fossil galls from the Eemian interglacial (130?000–115?000 years ago) of The Netherlands. The exceptionally well-preserved fossils can be attributed to extant species of Andricus gallwasps (Hymenoptera: Cynipidae) galling oaks (Quercus), and provide the first fossil evidence of gall attack by herbivorous inquiline gallwasps. Furthermore, phylogenetic placement of one fossil in a lineage showing obligate host plant alternation implies the presence of a second oak species, Quercus cerris, currently unknown from Eemian fossils in northwestern Europe. This contrasts with the southern European native range of Q. cerris in the current interglacial and suggests that gallwasp invasions following human planting of Q. cerris in northern Europe may represent a return to preglacial distribution limits. PMID:18559323

Stone, Graham N; van der Ham, Raymond W.J.M; Brewer, Jan G

2008-01-01

258

Fossil oak galls preserve ancient multitrophic interactions.  

PubMed

Trace fossils of insect feeding have contributed substantially to our understanding of the evolution of insect-plant interactions. The most complex phenotypes of herbivory are galls, whose diagnostic morphologies often allow the identification of the gall inducer. Although fossil insect-induced galls over 300Myr old are known, most are two-dimensional impressions lacking adequate morphological detail either for the precise identification of the causer or for detection of the communities of specialist parasitoids and inquilines inhabiting modern plant galls. Here, we describe the first evidence for such multitrophic associations in Pleistocene fossil galls from the Eemian interglacial (130000-115000 years ago) of The Netherlands. The exceptionally well-preserved fossils can be attributed to extant species of Andricus gallwasps (Hymenoptera: Cynipidae) galling oaks (Quercus), and provide the first fossil evidence of gall attack by herbivorous inquiline gallwasps. Furthermore, phylogenetic placement of one fossil in a lineage showing obligate host plant alternation implies the presence of a second oak species, Quercus cerris, currently unknown from Eemian fossils in northwestern Europe. This contrasts with the southern European native range of Q. cerris in the current interglacial and suggests that gallwasp invasions following human planting of Q. cerris in northern Europe may represent a return to preglacial distribution limits. PMID:18559323

Stone, Graham N; van der Ham, Raymond W J M; Brewer, Jan G

2008-10-01

259

An Indoor Fossil/Archeological Dig  

NSDL National Science Digital Library

In this activity, students will participate in a simulated fossil hunt or archeological excavation. Working in groups, they will excavate fossils or artifacts buried in a container and tag, number and label, and record the position and details of each object encountered. They will make site sketches as each layer is removed. When all the objects have been found, and all the information obtained, the group can compose a field report on the dig site that makes some inferences about the conditions that existed at the time the fossil/artifact was buried. A student worksheet is provided.

2011-06-24

260

Spitzer Digs Up Galactic Fossil  

NASA Technical Reports Server (NTRS)

[figure removed for brevity, see original site] Figure 1

[figure removed for brevity, see original site] Figure 2

This false-color image taken by NASA's Spitzer Space Telescope shows a globular cluster previously hidden in the dusty plane of our Milky Way galaxy. Globular clusters are compact bundles of old stars that date back to the birth of our galaxy, 13 or so billion years ago. Astronomers use these galactic 'fossils' as tools for studying the age and formation of the Milky Way.

Most clusters orbit around the center of the galaxy well above its dust-enshrouded disc, or plane, while making brief, repeated passes through the plane that each last about a million years. Spitzer, with infrared eyes that can see into the dusty galactic plane, first spotted the newfound cluster during its current pass. A visible-light image (inset of Figure 1) shows only a dark patch of sky.

The red streak behind the core of the cluster is a dust cloud, which may indicate the cluster's interaction with the Milky Way. Alternatively, this cloud may lie coincidentally along Spitzer's line of sight.

Follow-up observations with the University of Wyoming Infrared Observatory helped set the distance of the new cluster at about 9,000 light-years from Earth - closer than most clusters - and set the mass at the equivalent of 300,000 Suns. The cluster's apparent size, as viewed from Earth, is comparable to a grain of rice held at arm's length. It is located in the constellation Aquila.

Astronomers believe that this cluster may be one of the last in our galaxy to be uncovered.

This image composite was taken on April 21, 2004, by Spitzer's infrared array camera. It is composed of images obtained at four wavelengths: 3.6 microns (blue), 4.5 microns (green), 5.8 microns (orange) and 8 microns (red).

Galactic Fossil Found Behind Curtain of Dust In Figure 2, the image mosaic shows the same patch of sky in various wavelengths of light. While the visible-light image (left) shows a dark sky speckled with stars, infrared images (middle and right), reveal a never-before-seen bundle of stars, called a globular cluster. The left panel is from the California Institute of Technology's Digitized Sky Survey; the middle panel includes images from the NASA-funded Two Micron All-Sky Survey and the University of Wyoming Infrared Observatory (circle inset); and the right panel is from NASA's Spitzer Space Telescope.

The Two Micron All-Sky Survey false-color image was obtained using near-infrared wavelengths ranging from 1.3 to 2.2 microns. The University of Wyoming Observatory false-color image was captured on July 31, 2004, at wavelengths ranging from 1.2 to 2.2 microns. The Spitzer false-color image composite was taken on April 21, 2004, by its infrared array camera. It is composed of images obtained at four mid-infrared wavelengths: 3.6 microns (blue), 4.5 microns (green), 5.8 microns (orange) and 8 microns (red).

2004-01-01

261

Ashfall Fossil Beds State Historical Park  

NSDL National Science Digital Library

Approximately 12 million years ago, a massive volcano in the southwestern corner of Idaho erupted and spread a tremendous blanket of ash over a large area. Much of this ash settled over the grasslands of northeastern Nebraska. Animals consumed the ash-covered grasses, and eventually they began to perish as a result of consuming this abrasive powder. Eventually these animals and their skeletons became fossilized, and this area is now the Ashfall Fossil Beds State Historical Park. Visitors to the Park's website will be delighted to learn that they can view a range of images and videos from the fossil beds, along with an excellent interactive skeleton map that documents the fossilized remains on site. Also, the "Ashfall Geology" site is uniformly excellent, and it includes aerial views of the site and details about the geological formations in the area. Finally, the "Ashfall Animals" area contains information about the paleontological finds, which include five horse species and a saber-toothed deer.

262

Fossil energy program. Progress report, July 1980  

SciTech Connect

This report - the seventy-second of a series - is a compendium of monthly progress reports for the ORNL research and development programs that are in support of the increased utilization of coal and other fossil fuel alternatives to oil and gas as sources of clean energy. The projects reported this month include those for coal conversion development, chemical research and development, materials technology, component development and process evaluation, technical support to major liquefaction projects, process and program analysis, fossil energy environmental analysis, coal preparation and waste utilization, coal preparation plant automation, atmospheric fluidized bed coal combustor for cogeneration, technical support to the TVA fluidized bed combustion demonstration plant program, fossil energy applications assessments, performance assurance system support for fossil energy projects, international assessment of atmospheric fluidized bed combustion technology, and PFBC systems analysis.

McNeese, L. E.

1980-10-01

263

Hybrid solar-fossil fuel power generation  

E-print Network

In this thesis, a literature review of hybrid solar-fossil fuel power generation is first given with an emphasis on system integration and evaluation. Hybrid systems are defined as those which use solar energy and fuel ...

Sheu, Elysia J. (Elysia Ja-Zeng)

2012-01-01

264

Capturing and Storing Fossil-Fuel Carbon  

NASA Astrophysics Data System (ADS)

Can the global energy system continue to be dominated by fossil fuels throughout the 21st century without leading to an unacceptable rise in the concentration of atmospheric CO2? Yes, if a substantial fraction of the carbon in the fossil fuels can be captured and stored elsewhere than in the atmosphere. Of critical importance are: 1) the commercialization of a non-carbon fuel, presumably hydrogen, that is produced from fossil fuels in large-scale facilities in conjunction with CO2 capture, and 2) the storage of CO2 in geological formations, especially deep saline aquifers. Modeling and analysis has not yet identified any showstoppers. Hydrogen production from fossil fuels at refineries and ammonia plants is already fully commercial, as is injection of CO2 into oil reservoirs. Under development are hydrogen vehicles powered by internal combustion engines and by fuel cells. Carbon capture and storage appears to have the potential to play a major role in global environmental management.

Keith, David

2002-03-01

265

How a Dinosaur Became a Fossil  

NSDL National Science Digital Library

This interactive resource adapted from the Museum of Paleontology at the University of California, Berkeley shows how a dinosaur can be buried under sediment after it dies, become a fossil, and then become exposed and discovered by paleontologists.

2005-12-17

266

A fossil Aspergillus from Baltic amber.  

PubMed

A piece of Baltic amber (Tertiary, Eocene) contains an inclusion of a springtail (Collembola) which is overgrown by an Aspergillus species. The fossil fungus is described as A. collembolorum sp. nov. The excellent mode of preservation of the numerous conidiophores is remarkable and can be explained by sporulation in liquid resin. This is the second report of a fossil Aspergillus, the first being from Dominican amber. PMID:16175799

Dörfelt, Heinrich; Schmidt, Alexander R

2005-08-01

267

International Organisation of Palaeobotany: Plant Fossil Record  

NSDL National Science Digital Library

Users are able to search an extensive database of information on the plant fossil record, including descriptions and occurrences of modern genera and fossil species. Searches can be performed in a variety of ways: by Genera, description, taxonomy, occurrences, and by palaeogeographic maps. After locating the specific plant of interest in the database, the occurrences of that plant are then displayed in a palaeogeographic map.

268

Adventures in Paleontology: 36 Classroom Fossil Activities  

NSDL National Science Digital Library

Millions of years after vanishing from the Earth, dinosaurs still have the power to stir students' curiosity. Deepen that interest with Adventures in Paleontology, a series of lively hands-on activities especially for middle schoolers. This beautifully illustrated full color book features 36 activities that open students up to a variety of foundational sciences, including biology, geology, chemistry, physics, and astronomy. For example: � "How Do Fossils Form?" discusses how organisms become fossils and illustrates the concept with activities that simulate fossil-making processes. � "What Can You Learn From Fossils?" explores what fossils teach about ancient organisms. � "Mass Extinction and Meteor Collisions With Earth" discusses recently discovered links between meteor and asteroid impacts on Earth and the demise of animals like dinosaurs. Other chapters cover how to tell the age of the Earth; how dinosaurs evolved; and diversity, classification, and taxonomy. The final chapters offer humanistic perspectives on fossils in literature and art. As an attention-grabbing complement to the text, vivid full color illustrations show not just skeletons and animal tracks but also what dinosaurs probably looked like in their natural settings. Handy line drawings guide students through each step of the activities.

Slesnick, Irwin; Hansen, Thor

2006-01-01

269

Polymerization or Cyclic Dimerization: Solvent Dependent Homo-Coupling of Terminal Alkynes at HOPG Surface  

PubMed Central

Surface reactivity has become one of the most important issues in surface chemistry over the past few years. In this work, we, for the first time, have investigated the homo-coupling of a special terminal alkyne derivative on the highly oriented pyrolitic graphite (HOPG) surface. Using scanning tunneling microscopy (STM) technique, we have found that such coupling reaction seriously depends on the supramolecular assembly of the monomer on the studied substrate, whereas the latter appears an obvious solvent effect. As a result, the reaction in our system undergoes polymerization and cyclic dimerization process in 1-phenyloctane and 1,2,4-trichlorobenzene, respectively. That is to say, the solvent effect can be extended from the two-dimensional (2D) supramolecular self-assembly to surface chemical reactions, and the selective homo-coupling has been successfully achieved at the solid/liquid interface. PMID:24469357

Zhang, Xuemei; Liao, Lingyan; Wang, Shuai; Hu, Fangyun; Wang, Chen; Zeng, Qingdao

2014-01-01

270

Late Pliocene Homo and Hominid Land Use from Western Olduvai Gorge, Tanzania  

Microsoft Academic Search

Excavation in the previously little-explored western portion of Olduvai Gorge indicates that hominid land use of the eastern paleobasin extended at least episodically to the west. Finds included a dentally complete Homo maxilla (OH 65) with lower face, Oldowan stone artifacts, and butchery-marked bones dated to be between 1.84 and 1.79 million years old. The hominid shows strong affinities to

Robert J. Blumenschine; Charles R. Peters; Fidelis T. Masao; Ronald J. Clarke; Alan L. Deino; Richard L. Hay; Carl C. Swisher; Ian G. Stanistreet; Gail M. Ashley; Lindsay J. McHenry; Nancy E. Sikes; Nikolaas J. van der Merwe; Joanne C. Tactikos; Amy E. Cushing; Daniel M. Deocampo; Jackson K. Njau; James I. Ebert

2003-01-01

271

Call Routing Algorithm for NGN Multimedia Communication Based on Quasi-homo-administrative Domain  

Microsoft Academic Search

Aimed at the lower access efficiency between administrative domains (AD) in NGN multimedia communication, we adopted the coding pattern for telephone number based on ITU-T E.164 protocol and the method in resolving process of DNS, and put forward a routing addressing algorithm for inter-domain communication. This algorithm was based on quasi-homo-administrative domain (QUAD). It used H.225 Annex G protocol messages

Yu Zhanwu; Li Rui; Pan Shaoming

2006-01-01

272

Passion's re-territorializations: mapping the mixed semiotics of unsafe homo passional assemblages  

Microsoft Academic Search

This paper conducts a mixed semiotics of unsafe homo passional assemblages. It begins with an exposition of Deleuze and Guattari's instructions for mapping the multidimensional circuitry of assemblages along the generative and transformative poles. Unsafe sex is a line of desiring movement involving expressive matter from the pick-up machine. After HIV\\/AIDS, the pick-up machine's de-territorialised movements have been problematised, their

Craig Osmond

2010-01-01

273

Multiplex Detection of Homo- and Heterodimerization of G Protein-Coupled Receptors by Proximity Biotinylation  

PubMed Central

Dimerization of G protein-coupled receptors (GPCRs) represents a potential mechanism by which GPCR functions are regulated. Several resonance energy transfer (RET)-based methods have revealed GPCR homo- and heterodimerization. However, interpretation of an increase in FRET efficiency could be attributed to either dimerization/oligomerization events or conformational changes within an already dimerized/oligomerized receptor complex. Furthermore, RET-based methods can only measure pairwise dimerization, and cannot easily achieve multiplex detection. In this study, we applied proximity-based biotinylation for detecting receptor dimerization by utilizing a specific enzyme-substrate pair that are fused to GPCRs. The biotin ligase BirA is fused to CXCR4 and site-specifically biotinylates an acceptor peptide (AP) in the presence of biotin. As a test case for our newly developed assay, we have characterized the homo-dimerization of chemokine receptor CXCR4 and heterodimerization of CXCR4 with CCR2 or CCR5. The degree of biotinylation varies with the amount of GPCR-AP as well as biotinylation time. Using enzyme/substrate receptor pairs and measuring receptor biotinylation, we demonstrate that CXCR4 can homo-dimerize and hetero-dimerize with CCR2 and CCR5. The effect of CXCL12, agonist for CXCR4, was found to decrease surface biotinylation of CXCR4-AP. This effect is due to a combination of CXCR4 endocytosis and stabilization of CXCR4 homodimers. Finally, when CXCR4-AP, CCR2-AP, and CCR5-AP were expressed together, we observed CXCR4-CXCR4 homodimers and CXCR4-CCR2 and CXCR4-CCR5 heterodimers. The newly developed assay opens new opportunity for multiplex detection for GPCR homo- and heterodimerization within the same cellular context. PMID:24691126

Liu, Allen P.

2014-01-01

274

Sedimentation Analysis of Novel DNA Structures Formed by Homo-Oligonucleotides  

Microsoft Academic Search

Sedimentation velocity analysis has been used to examine the base-specific structural conformations and unusual hydrogen bonding patterns of model oligonucleotides. Homo-oligonucleotides composed of 8–28 residues of dA, dT, or dC nucleotides in 100mM sodium phosphate, pH 7.4, at 20°C behave as extended monomers. Comparison of experimentally determined sedimentation coefficients with theoretical values calculated for assumed helical structures show that dT

Danny M. Hatters; Leanne Wilson; Benjamin W. Atcliffe; Terrence D. Mulhern; Nancy Guzzo-Pernell; Geoffrey J. Howlett

2001-01-01

275

Recent Human Evolution in East Asia and Australasia  

Microsoft Academic Search

In both East Asia and Australasia arguments for evolutionary continuity between middle-late Pleistocene hominid populations and modern Homo sapiens are of long standing. In both regions, however, problems of chronological distribution, dating and preservation of hominid skeletal materials provide an effective barrier to extending regional sequences back to `archaic' Homo sapiens or Homo erectus. The earliest securely dated modern Homo

Peter Brown

1992-01-01

276

Yukon gold mine yields ancient horse fossil 700,000yearold fossil discovered in Yukon permafrost yields genome world record.  

E-print Network

Yukon gold mine yields ancient horse fossil 700,000yearold fossil discovered in Yukon permafrost an unusually large horse fossil in the Yukon permafrost, he knew it was important. Now, in a new study published in the journal Nature, this fossil is rewriting the story of equine evolution as the ancient

Machel, Hans

277

A Fossil Hunt Tells the Age of Sediments  

NSDL National Science Digital Library

In this activity, students will identify an assemblage of fossils, determine their age, evaluate the fossil population, and make some inferences about the ancient environment in which they existed. The discovery aspect of this exercise is that all of the fossils the students will find existed together in only one time period. The environment of these fossils, a fresh water lake, is ascertained from using the fossil guidebook. A student worksheet and discussion questions are provided.

2011-06-22

278

Mineralogy of fossil resins in Northern Eurasia  

NASA Astrophysics Data System (ADS)

The investigation is focused on identification and origin of fossil resins from the Cretaceous, Tertiary, and Quaternary sediments of Northern Eurasia on the basis of detailed study of their physical and chemical characteristics: morphology; size; mass; density; optical, mechanical, and thermal properties; chemical composition; etc. The composition of amorphous organic minerals with polymeric structure, fossil resins included, is studied with IR spectrometry, the EPR method, derivatography at low heating rates, XRD, chemical analysis, emission spectrometry, etc. The results of investigation summarized for the Baltic-Dnieper, North Siberian, and Far East amber-bearing provinces show some similarity of fossil resins in combination with specific features inherent to each province. Resins from the Baltic-Dnieper province should be termed as amber (succinite). Their variety is the most characteristic of Northern and Eastern Europe. Amber-like fossil resins from the North Siberian and Far East provinces are irrelevant to succinite. They usually occur as brittle resins, namely, retinite and gedanite, without jewelry value. Viscous fossil resin rumänite with an expected high economic value occurs in the Far East, on the shore of Sakhalin Island.

Bogdasarov, M. A.

2007-12-01

279

A fungal analog for newfoundland ediacaran fossils?  

PubMed

We propose that some of the more conspicuous Ediacaran fossils from the Avalon Peninsula of Newfoundland, including Aspidella, Charnia, and Charniodiscus, were biologically similar to members of the Kingdom Fungi. These organisms were multicellular or multinuclear, lived below the photic zone, could not move or defoul themselves, did not exhibit taphonomic shrinkage, and were not transported or moved. Aspidella, in particular, appears to exhibit indeterminate growth without a maximum size constraint, and appears to show growth zonations similar to modern mycelia. Other fossils from this deposit exhibit a fractal-like growth pattern. Together, these features falsify algal, lichen, and metazoan interpretations of these fossils, yet reflect characteristics of modern fungal mycelia. We emphasize that although no Mistaken Point fossil appears to be a metazoan, not all of the Mistaken Point taxa, and not all of the Ediacaran organisms in general, can reasonably be interpreted using a fungal analogy. Furthermore, the hypothesis that these fossils were functionally fungus-like need not imply that the organisms were members of the crown-group Fungi. We propose further tests for evaluating both this functional hypothesis and the phylogenetic hypothesis that these organisms were members of the total-group Fungi. PMID:21680417

Peterson, Kevin J; Waggoner, Ben; Hagadorn, James W

2003-02-01

280

IGM heating in fossil galaxy groups  

NASA Astrophysics Data System (ADS)

We study intergalactic medium (IGM) heating in a sample of five fossil galaxy groups by using their radio properties at 610 MHz and 1.4 GHz. The power by radio jets introducing mechanical heating for the sampled objects is not sufficient enough to suppress the cooling flow. Therefore, we discussed shock-, vortex heating, and conduction as alternative heating processes. Further, the 1.4 GHz and 610 MHz radio luminosities of fossil groups are compared to a sample of normal galaxy groups of the same brightest group galaxies (BGGs), stellar mass, and total group stellar mass, quantified using the K-band luminosity. It appears that the fossil BGGs are under luminous at 1.4 GHz and 610 MHz for a given BGG stellar mass and luminosity, in comparison to a general population of the groups. In addition, we explore how the bolometric radio luminosity of fossil sample depends on clusters and groups characteristics. Using the HIghest X-ray FLUx Galaxy Cluster Sample (HIFLUGCS) as a control sample we found that the large-scale behaviours of fossil galaxy groups are consistent with their relaxed and virialized nature.

Miraghaei, H.; Khosroshahi, H. G.; Klöckner, H.-R.; Ponman, T. J.; Jetha, N. N.; Raychaudhury, S.

2014-10-01

281

Early Pleistocene 40Ar/39Ar ages for Bapang Formation hominins, Central Jawa, Indonesia  

PubMed Central

The Sangiran dome is the primary stratigraphic window for the Plio-Pleistocene deposits of the Solo basin of Central Jawa. The dome has yielded nearly 80 Homo erectus fossils, around 50 of which have known findspots. With a hornblende 40Ar/39Ar plateau age of 1.66 ± 0.04 mega-annum (Ma) reportedly associated with two fossils [Swisher, C.C., III, Curtis, G. H., Jacob, T., Getty, A. G., Suprijo, A. & Widiasmoro (1994) Science 263, 1118–1121), the dome offers evidence that early Homo dispersed to East Asia during the earliest Pleistocene. Unfortunately, the hornblende pumice was sampled at Jokotingkir Hill, a central locality with complex lithostratigraphic deformation and dubious specimen provenance. To address the antiquity of Sangiran H. erectus more systematically, we investigate the sedimentary framework and hornblende 40Ar/39Ar age for volcanic deposits in the southeast quadrant of the dome. In this sector, Bapang (Kabuh) sediments have their largest exposure, least deformation, and most complete tephrostratigraphy. At five locations, we identify a sequence of sedimentary cycles in which H. erectus fossils are associated with epiclastic pumice. From sampled pumice, eight hornblende separates produced 40Ar/39Ar plateau ages ranging from 1.51 ± 0.08 Ma at the Bapang/Sangiran Formation contact, to 1.02 ± 0.06 Ma, at a point above the hominin-bearing sequence. The chronological sequence of 40Ar/39Ar ages follows stratigraphic order across the southeast quadrant. An intermediate level yielding four nearly complete crania has an age of about 1.25 Ma. PMID:11309488

Larick, Roy; Ciochon, Russell L.; Zaim, Yahdi; Sudijono; Suminto; Rizal, Yan; Aziz, Fachroel; Reagan, Mark; Heizler, Matthew

2001-01-01

282

Fossil evidence of the zygomycetous fungi.  

PubMed

Molecular clock data indicate that the first zygomycetous fungi occurred on Earth during the Precambrian, however, fossil evidence of these organisms has been slow to accumulate. In this paper, the fossil record of the zygomycetous fungi is compiled, with a focus on structurally preserved Carboniferous and Triassic fossils interpreted as zygosporangium-gametangia complexes and resembling those of modern Endogonales. Enigmatic microfossils from the Precambrian to Cenozoic that have variously been interpreted as, or compared to, zygomycetous fungi are also discussed. Among these, the spherical structures collectively termed 'sporocarps' are especially interesting because of their complex investments and abundance in certain Carboniferous and Triassic rocks. Circumstantial evidence suggests that at least some 'sporocarp' types represent mantled zygosporangia. Zygomycetous fungi probably were an important element in terrestrial paleoecosystems at least by the Carboniferous. PMID:24027344

Krings, M; Taylor, T N; Dotzler, N

2013-06-01

283

Eumetazoan fossils in terminal Proterozoic phosphorites?  

PubMed Central

Phosphatic sedimentary rocks preserve a record of early animal life different from and complementary to that provided by Ediacaran fossils in terminal Proterozoic sandstones and shales. Phosphorites of the Doushantuo Formation, South China, contain eggs, egg cases, and stereoblastulae that document animals of unspecified phylogenetic position; small fossils containing putative spicules may specifically record the presence of sponges. Microfossils recently interpreted as the preserved gastrulae of cnidarian and bilaterian metazoans can alternatively be interpreted as conventional algal cysts and/or egg cases modified by diagenetic processes known to have had a pervasive influence on Doushantuo phosphorites. Regardless of this interpretation, evidence for Doushantuo eumetazoans is provided by millimeter-scale tubes that display tabulation and apical budding characteristic of some Cnidaria, especially the extinct tabulates. Like some Ediacaran remains, these small, benthic, colonial fossils may represent stem-group eumetazoans or stem-group cnidarians that lived in the late Proterozoic ocean. PMID:11095754

Xiao, Shuhai; Yuan, Xunlai; Knoll, Andrew H.

2000-01-01

284

Valdosta State University's Virtual Museum of Fossils  

NSDL National Science Digital Library

Valdosta State University's Virtual Museum of Fossils offers information on animals since the Precambrian era. The website offers two navigation options. In the Find an Animal section, users can view fossils by clicking on different areas of the geologic timescales for Prokaryotes, Eukaryotes, Invertebrates, and Vertebrates. In the Choose a Time section, students can learn about the major characteristics of each era. For each period, this link also offers a map of the world, the characteristics of the landscape at the time, and pictures of fossils of the animals that lived during the period. While the Take a Tour link is still under construction, the abundance of information covering the geologic past makes the site worth the visit.

285

Brachiopod exercise for FossilPlot  

NSDL National Science Digital Library

Students are taught how to use FossilPlot software in the lab prior to this exercise. Students work individual to work through the short exercise, handing in a copy of the diversity graphs for the brachiopod orders (which will be tested in the following midterm) and a completed worksheet. The exercise reinforces the main functions of FossilPlot and addresses basic concepts on diversity and biostratigraphy. Once the assignments are collected and graded, we discuss the outcomes of the exercise in class.

Leif Tapanila

286

How Do Scientists Find Dinosaur Fossils?  

NSDL National Science Digital Library

This lesson plan is about the process by which paleontologists locate, excavate, and study dinosaurs. Students will write journal entries pretending they are on a dinosaur dig. They will also make fact sheets about this recently discovered Jobaria dinosaur; place Jobaria into a timeline to indicate the periods in which it lived; visit a website to learn about the steps involved in finding and excavating dinosaur fossils, then list these steps and explain their importance; describe what the bones in an interactive Jobaria skeleton indicate about this dinosaur; and view pictures of a trip teenagers took to look for dinosaur fossils.

287

Fossils, Genes and The Origin of Organs  

SciTech Connect

A toolkit of experimental and comparative biology can be applied to understand the great transformations in the history of life. Expeditionary paleontology can be used to target key nodes of the tree of life for which new fossils can provide insights into major morphological transformations. These fossils often have intermediate conditions that allow extant creatures to be compared in new ways. The tools of developmental genetics can then be used to explore these new comparisons to understand the genetic basis for macroevolutionary change. These different approaches can be used to predict new discoveries and this is only possible because of the empirical content of the tree of life.

Shubin, Neil (University of Chicago) [University of Chicago

2011-04-20

288

Insect diversity in the fossil record  

NASA Technical Reports Server (NTRS)

Insects possess a surprisingly extensive fossil record. Compilation of the geochronologic ranges of insect families demonstrates that their diversity exceeds that of preserved vertebrate tetrapods through 91 percent of their evolutionary history. The great diversity of insects was achieved not by high origination rates but rather by low extinction rates comparable to the low rates of slowly evolving marine invertebrate groups. The great radiation of modern insects began 245 million years ago and was not accelerated by the expansion of angiosperms during the Cretaceous period. The basic trophic machinery of insects was in place nearly 100 million years before angiosperms appeared in the fossil record.

Labandeira, C. C.; Sepkoski, J. J. Jr; Sepkoski JJ, J. r. (Principal Investigator)

1993-01-01

289

Fossil generation restructuring in the Ukraine  

SciTech Connect

This paper describes the Ukrainian electrical system as it was in 1991, defines the need for restructuring, outlines the restructuring process, identifies a number of major obstacles that are hindering the implementation of the fossil generation, restructuring process, and points out major problems in the coal procurement system. It describes the visits to several Ukrainian power plants, defines restructuring success to date, makes suggestions for improved restructuring progress, highlights lessons learned, and enlightens the audience on the opportunities of investing in the Ukrainian power generation industry. The primary focus is on the Fossil Generator Advisor task, which was carried out under the direction of Hagler Bailly Consulting, Inc. (Hagler Bailly).

Galambas, J.W. [Hagler Bailly Consulting, Inc., Boulder, CO (United States)

1996-12-31

290

Microbial Fossils Detected in Desert Varnish  

NASA Technical Reports Server (NTRS)

Mars Global Surveyor Thermal Emission Spectrometer data indicate regions with significant levels of hematite (_Fe2O3). Fe-oxides, like hematite, can form as aqueous mineral precipitates and as such may preserve microscopic fossils or other biosignatures. Several potential terrestrial analogues to martian hematite like hydrothermal vents have preserved microfossils. Microbial fossilization in Fe-oxides is often a function of biomineralization. For example, goethite (FeO2H) encrustation of fungal mycelia from the mid-Tertiary preserved fungal morphologies such that their genera could be determined.

Flood, B. E.; Allen, C.; Longazo, T.

2003-01-01

291

Trace fossil assemblages in selected shelf sandstones  

E-print Network

TRACE FOSSIl. ASSEMBLAGES IN SELECTED SHELF SANDSTONES A Thesis by KATHLEEN ANN LOCKE Submitted to the Graduate Co11ege of Texas A&M University in partial fu1, i11ment of the requirement for the degree of MASTER Gl- SCIENCE August lg83... Medor 'ul. ', ect: Leo'. ogy TRACE FOSSIL ASSEMBLAGES IN SELECTED SHELF SANDSTONES A Thesis by KATHLEEN ANN LOCKE Approved as to style and content by: Robert R. Berg (Chairman of Committee) Robert . St on (Member) Rezneat M. Darnell (Member...

Locke, Kathleen Ann

2012-06-07

292

Molecular Determinants of Arenavirus Z Protein Homo-Oligomerization and L Polymerase Binding?  

PubMed Central

The arenavirus Z is a zinc-binding RING protein that has been implicated in multiple functions during the viral life cycle. These roles of Z involve interactions with viral and cellular proteins that remain incompletely understood. In this regard, Z inhibits viral RNA transcription and replication through direct interaction with the viral L polymerase. Here, we defined the L-binding domain of Tacaribe virus (TCRV) Z protein and the structural requirements mediating Z homo-oligomerization. By using site-directed mutagenesis, coimmunoprecipitation, and functional assays, we showed that residues R37, N39, W44, L50, and Y57, located around the zinc coordination site I, play a critical role in the Z-L interaction. We also found that Z protein from either TCRV or the pathogenic Junin virus (JUNV) self-associates into oligomeric forms in mammalian cells. Importantly, mutation of the myristoylation site, the strictly conserved residue G at position 2, severely impaired the ability of both TCRV Z and JUNV Z to self-interact as well as their capacity to accumulate at the plasma membrane, strongly suggesting that Z homo-oligomerization is associated with its myristoylation and cell membrane targeting. In contrast, disruption of the RING structure or substitution of W44 or N39, which are critical for L protein recognition, did not affect Z self-binding. Overall, the data presented here indicate that homo-oligomerization is not a requirement for Z-L interaction or Z-mediated polymerase activity inhibition. PMID:21957305

Loureiro, Maria Eugenia; Wilda, Maximiliano; Levingston Macleod, Jesica M.; D'Antuono, Alejandra; Foscaldi, Sabrina; Buslje, Cristina Marino; Lopez, Nora

2011-01-01

293

Remote enantioselective Friedel-Crafts alkylations of furans through HOMO activation.  

PubMed

Catalytic asymmetric Friedel-Crafts alkylation is a powerful protocol for constructing a chiral C(sp(2))-C(sp(3)) bond. Most previous examples rely on LUMO activation of the electrophiles using chiral catalysts with subsequent attack by electron-rich arenes. Presented herein is an alternative strategy in which the HOMO of the aromatic ??system of 2-furfuryl ketones is raised through the formation of a formal trienamine species using a chiral primary amine. Exclusive regioselective alkylation at the 5-position occurred with alkylidenemalononitriles, and high reactivity and excellent enantioselectivity (up to 95% ee) was obtained by this remote activation. PMID:24756964

Li, Jun-Long; Yue, Cai-Zhen; Chen, Peng-Qiao; Xiao, You-Cai; Chen, Ying-Chun

2014-05-19

294

Brief communication: "Pathological" deformation in the skull of LB1, the type specimen of Homo floresiensis.  

PubMed

If the holotype of Homo floresiensis, LB1, suffered from a severe developmental pathology, this could undermine its status as the holotype of a new species. One of the proposed pathological indicators that still remains untested is asymmetric distortion in the skull of LB1 (Jacob et al.: Proc Natl Acad Sci USA 103 (2006) 13421-13426). Here, we present evidence that LB1 exhibits antemortem craniofacial deformities that are consistent with posterior deformational (positional) plagiocephaly. This is a relatively common condition in modern people with no serious associated health problems and does not represent a severe developmental abnormality in LB1. PMID:19358291

Kaifu, Yousuke; Baba, Hisao; Kurniawan, Iwan; Sutikna, Thomas; Saptomo, E Wahyu; Jatmiko; Awe, Rokhus Due; Kaneko, Tsuyoshi; Aziz, Fachroel; Djubiantono, Tony

2009-09-01

295

Are hydrothermal vent animals living fossils?  

Microsoft Academic Search

Since their discovery in 1977, hydrothermal vent communities have provided many surprises about life in the deep sea and in extreme environments. It has been suggested that vent communities contain many living fossils and that deep-sea chemosynthetic environments, such as vents and hydrocarbon seeps, are buffered from extinction events that affect the photic zone. This hypothesis is based on the

Crispin T. S. Little; Robert C. Vrijenhoek

2003-01-01

296

Mass Extinctions in the Marine Fossil Record  

Microsoft Academic Search

A new compilation of fossil data on invertebrate and vertebrate families indicates that four mass extinctions in the marine realm are statistically distinct from background extinction levels. These four occurred late in the Ordovician, Permian, Triassic, and Cretaceous periods. A fifth extinction event in the Devonian stands out from the background but is not statistically significant in these data. Background

David M. Raup; J. John Sepkoski

1982-01-01

297

Insect Diversity in the Fossil Record  

Microsoft Academic Search

Insects possess a surprisingly extensive fossil record. Compilation of the geochronologic ranges of insect families demonstrates that their diversity exceeds that of preserved vertebrate tetrapods through 91 percent of their evolutionary history. The great diversity of insects was achieved not by high origination rates but rather by low extinction rates comparable to the low rates of slowly evolving marine invertebrate

Conrad C. Labandeira; J. John Sepkoski Jr.

1993-01-01

298

Fossilized Gravitational Wave Relic and Primordial Clocks  

E-print Network

If long wavelength primordial tensor modes are coupled to short wavelength scalar modes, the scalar curvature two-point function will have an off-diagonal component. This `fossil' remnant is a signature of a mode coupling that cannot be achieved in single clock inflation. Any constraint on its presence allows a cross check of the relationship between the dynamical generation of the fluctuations and the evolution of the inflationary background. We use the example of non-Bunch Davies initial states for the tensor and scalar modes to demonstrate that physically reasonable fossils, consistent with current data, can be observable in the near future. We illustrate how the fossil off-diagonal power spectrum is a complementary probe to the squeezed limit bispectra of the scalar and tensor sectors individually. We also quantify the relation between the observable signal and the squeezed limit bispectrum for a general scalar-scalar-fossil coupling, and note the effect of superhorizon tensor modes on the anisotropy in scalar modes.

Suddhasattwa Brahma; Elliot Nelson; Sarah Shandera

2014-05-01

299

Deciphering whale origins with molecules and fossils  

Microsoft Academic Search

Recent efforts by paleontologists to find fossils that record the origin of whales have yielded an impressive collection of transitional forms from the Eocene. Simultaneously, molecular biologists have dramatically increased the genetic information relevant to whale phylogeny. Combined analyses of the available data indicate areas of congruence but also gross conflict between characters from extinct and extant organisms. The incongruence

John Gatesy; Maureen A. O'Leary

2001-01-01

300

Introduction Fossil age constraints for continental sedimentary  

E-print Network

) for sedimentary rocks exposed primarily on Hitra and small islands south of Smøla; Early to Mid Devonian agesIntroduction Fossil age constraints for continental sedimentary deposits are invariably more; Osmundsen & Andersen 2001), precise dating of the Devonian sedimentary basins has been particularly

Andersen, Torgeir Bjørge

301

Fossils: An Ancient Sea in Indiana  

NSDL National Science Digital Library

In this interactive activity from the Children's Museum of Indianapolis, Indiana, examine a piece of the ancient Borden Sea in what is now central Indiana. Explore the types of fossils found there and the clues they offer to ancient life on Earth.

Foundation, Wgbh E.

2005-10-21

302

Fossil Insect from the British Coal Measures  

Microsoft Academic Search

IN 1922 I described the wing of a fossil insect with Odonate affinities, from the Upper Coal Measure of Ayrshire, under the name of Tillyardia1. My attention has been directed to the preoccupation of the name Tillyardia2 in Coleoptera.

H. Bolton

1934-01-01

303

From fossil fuels to renewable energies  

Microsoft Academic Search

This paper describes the model of an industrial society based on fossil fuels whose supply decreases and the society is forced to develop alternative energy sources. It is conceived as an abstract model that captures the basic aspect of such a change, but in a simple and schematic way. Despite this, most of the important dynamics of this problem are

Margarita Mediavilla; Luis Javier Miguel; Carlos de Castro

304

Realistic ocean energy alternatives to fossil fuels  

Microsoft Academic Search

The US Commission on Ocean Policy endorsed the Administrations complete dependence on fossil fuels as the primary energy source for the nation. Two very significant alternatives were rejected or neglected. The first alternative was sea based semi submerged nuclear power plant ships deployed in a line paralleling the coastline of the United States. The US has developed and deployed hundreds

John Piña Craven

2005-01-01

305

Solar hydrogen: Moving beyond fossil fuels  

Microsoft Academic Search

The prospect of using hydrogen from water as a substitute for oil and other fossil fuels has moved from the realm of dream to distinct possibility. What has made hydrogen worth reconsidering now are recent dramatic developments in photovoltaic (PV) cells that directly convert sunlight into electricity. This book discusses the advantages of a hydrogen-based economy and how such a

J. M. Ogden; R. H. Williams

1989-01-01

306

The Fascinating Story of Fossil Fuels  

ERIC Educational Resources Information Center

How this energy source was created, its meaning to mankind, our drastically reduced supply, and why we cannot wait for nature to make more are considered. Today fossil fuels supply 96 percent of the energy used but we must find alternate energy options if we are to combat the energy crisis. (BL)

Asimov, Isaac

1973-01-01

307

Fossil fuels supplies modeling and research  

SciTech Connect

The fossil fuel supplies modeling and research effort focuses on models for US Strategic Petroleum Reserve (SPR) planning and management. Topics covered included new SPR oil valuation models, updating models for SPR risk analysis, and fill-draw planning. Another task in this program area is the development of advanced computational tools for three-dimensional seismic analysis.

Leiby, P.N.

1996-06-01

308

A phylogenetic system of Clavatoraceae (fossil Charophyta)  

Microsoft Academic Search

Using the cladistic method of Hennig a phylogenetic system of Clavatoraceae (fossil Charophyta) is proposed. A number of new combinations arise from this study.The family Clavatoraceae is composed of three monophyla: (1) the Atopocharoidae, which are defined by presenting a utricle with a radial symmetry formed by the superposition of two whorls of spine-shaped bracts and includes traditional members plus

C. Martín-Closas

1996-01-01

309

Fossil Cores In The Kepler Data  

NASA Astrophysics Data System (ADS)

Most gas giant exoplanets with orbital periods < few days are unstable against tidal decay and may be tidally disrupted before their host stars leave the main sequence. These gas giants probably contain rocky/icy cores, and so their cores will be stranded near their progenitor's Roche limit (few hours orbital period). These fossil cores will evade the Kepler mission's transit search because it is focused on periods > 0.5 days, but finding these fossil cores would provide unprecedented insights into planetary interiors and formation ? e.g., they would be a smoking gun favoring formation of gas giants via core accretion. We propose to search for and characterize fossil cores in the Kepler dataset. We will vet candidates using the Kepler photometry and auxiliary data, collect ground-based spectra of the host stars and radial-velocity (RV) and adaptive optics (AO) data to corroborate candidates. We will also constrain stellar tidal dissipation efficiencies (parameterized by Q) by determining our survey's completeness, elucidating dynamical origins and evolution of exoplanets even if we find no fossil cores. Our preliminary search has already found several dozen candidates, so the proposed survey has a high likelihood of success.

Jackson, Brian

310

Paranasal pneumatization in extant and fossil Cercopithecoidea.  

PubMed

Unlike most primates, extant cercopithecoids lack maxillary sinuses, which are pneumatic spaces in the facial skeleton lateral of the nasal cavity proper. Character state analysis of living cercopithecoids across well-supported topologies suggests that the sinus was lost at the origin of the superfamily, only to have evolved again convergently in extant macaques. Recent work has shown that a) the 'early loss' hypothesis is supported by the lack of any pneumatization in Victoriapithecus, a stem cercopithecoid, b) like extant macaques, the fossil cercopithecine Paradolichopithecus shows evidence of presence of the maxillary sinus (MS), and c) unlike extant colobines, the fossil colobine Libypithecus also possesses a maxillary sinus. To more fully assess the pattern of cercopithecoid sinus evolution, fossil taxa from both subfamilies (Colobinae, Cercopithecinae) were examined both visually and by computed tomography (CT). The observations were evaluated according to standard anatomical criteria for defining sinus spaces, and compared with data from all extant Old World monkey genera. Most taxa examined conformed to the pattern already discerned from extant cercopithecoids. Maxillary sinus absence in Theropithecus oswaldi, Mesopithecus, and Rhinocolobus is typical for all extant cercopithecids except Macaca. The fossil macaque Macaca majori possesses a well-developed maxillary sinus, as do all living species of the genus. Cercopithecoides, on the other hand, differs from all extant colobines in possessing a maxillary sinus. Thus, paranasal pneumatization has reemerged a minimum of two and possibly three times in cercopithecoids. The results suggest that maxillary sinus absence in cercopithecoids is due to suppression, rather than complete loss. PMID:18068215

Rae, Todd C

2008-03-01

311

Exceptional fossil preservation and the cambrian explosion.  

PubMed

Exceptionally preserved, non-biomineralizing fossils contribute importantly to resolving details of the Cambrian explosion, but little to its overall patterns. Six distinct "types" of exceptional preservation are identified for the terminal Proterozoic-Cambrian interval, each of which is dependent on particular taphonomic circumstances, typically restricted both in space and time. Taphonomic pathways yielding exceptional preservation were particularly variable through the Proterozoic-Cambrian transition, at least in part a consequence of contemporaneous evolutionary innovations. Combined with the reasonably continuous record of "Doushantuo-type preservation," and the fundamentally more robust records of shelly fossils, phytoplankton cysts and trace fossils, these taphonomic perturbations contribute to the documentation of major evolutionary and biogeochemical shifts through the terminal Proterozoic and early Cambrian.Appreciation of the relationship between taphonomic pathway and fossil expression serves as a useful tool for interpreting exceptionally preserved, often problematic, early Cambrian fossils. In shale facies, for example, flattened non-biomineralizing structures typically represent the remains of degradation-resistant acellular and extracellular "tissues" such as chaetae and cuticles, whereas three-dimensional preservation represents labile cellular tissues with a propensity for attracting and precipitating early diagenetic minerals. Such distinction helps to identify the acuticular integument of hyolithids, the chaetae-like nature of Wiwaxia sclerites, the chaetognath-like integument of Amiskwia, the midgut glands of various Burgess Shale arthropods, and the misidentification of deposit-feeding arthropods in the Chengjiang biota. By the same reasoning, putative lobopods in the Sirius Passet biota and putative deuterostomes in the Chengiang biota are better interpreted as arthropods. PMID:21680421

Butterfield, Nicholas J

2003-02-01

312

The living fossil of human judgment.  

PubMed

Although the biases and anomalies characterizing psychometric data should serve as conclusive evidence of systematic flaws in scientific methodology, these problems are usually ignored, which reduces empirical psychology to the closed system of its error theory. However, psychometric scores are ambiguous, and response-shifts and fluctuating validities point to fundamental differences in what the measuring-apparatus questionnaire records and how the measuring-apparatus person judges. Therefore, empirical methods fail when psychology requires evidence-based knowledge about cognitive processes and phenomena. Correcting these flaws requires a reassessment of basic scientific premises and careful consideration of Homo sapiens' biosemiotic heuristics. Based on comprehensive biopsychosocial, data, the author reconstructs the evolutionary axioms of self-referenced cognitions and reveals what is usually obscured by the axioms of normal science. He substantiates the need for a paradigm shift toward basic bio-cultural principles and an evolutionary understanding of human thinking and behavior. PMID:24615167

Schwarz, Michael

2014-06-01

313

Initiation of the microgene polymerization reaction with non-repetitive homo-duplexes  

SciTech Connect

Microgene Polymerization Reaction (MPR) is used as an experimental system to artificially simulate evolution of short, non-repetitive homo-duplex DNA into multiply-repetitive products that can code for functional proteins. Blunt-end ligation by DNA polymerase is crucial in expansion of homo-duplexes (HDs) into head-to-tail multiple repeats in MPR. The propagation mechanism is known, but formation of the initial doublet (ID) by juxtaposing two HDs and polymerization through the gap has been ambiguous. Initiation events with pairs of HDs using Real-Time PCR were more frequent at higher HD concentrations and slightly below the melting temperature. A process molecularity of about 3.1, calculated from the amplification efficiency and the difference in PCR cycles at which propagation was detected at varying HD concentrations, led to a simple mechanism for ID formation: the gap between two HDs is bridged by a third. Considering thermodynamic aspects of the presumed intermediate 'nucleation complex' can predict relative propensity for the process with other HDs.

Itsko, Mark [Department of Life Sciences, Faculty of Natural Sciences, Ben-Gurion University of the Negev, PO Box 653, Be'er-Sheva 84105 (Israel)], E-mail: ariehz@bgu.ac.il; Zaritsky, Arieh [Department of Life Sciences, Faculty of Natural Sciences, Ben-Gurion University of the Negev, PO Box 653, Be'er-Sheva 84105 (Israel); Rabinovitch, Avinoam [Department of Physics, Faculty of Natural Sciences, Ben-Gurion University of the Negev, PO Box 653, Be'er-Sheva 84105 (Israel); Ben-Dov, Eitan [Department of Biotechnology Engineering, Faculty of Engineering Sciences, Ben-Gurion University of the Negev, PO Box 653, Be'er-Sheva 84105 (Israel); Achva Academic College, MP Shikmim, 79800 (Israel)

2008-04-11

314

Fossil Woodwardia virginica Foliage From the Middle Miocene Yakima Canyon  

NSDL National Science Digital Library

Fossil Woodwardia virginica foliage from the middle Miocene Yakima Canyon flora of central Washington State, USA. Vegetative and fertile features of this fossil are remarkably similar to those of the modern ""Virginia chain fern"" of the Atlantic coastal region, USA.

Kathleen B. Pigg (Arizona State University;Department of Plant Biology ADR;POSTAL)

2004-03-09

315

Fossil Record Accurately Reflects Recent Flowering of Marine Biodiversity  

NSF Publications Database

... Lane (703) 292-8550 hlane@nsf.gov Fossil Record Accurately Reflects Recent Flowering of Marine ... produced by the inconsistencies of the fossil record, says a team of paleontologists led by the ...

316

Fossil Groups in the Sloan Digital Sky Survey  

E-print Network

A search for fossil groups in the Sloan Digital Sky Survey was performed using virtual observatory tools. A cross-match of the positions of all SDSS Luminous Red Galaxies (with r fossil groups. Considering this sample, the estimated space density of fossil systems is $n =(1.0 \\pm 0.6) \\times 10^{-6}$ $h_{50}^3$ Mpc$^{-3}$.

Walter A. Santos; Claudia Mendes de Oliveira; Laerte Sodré Jr

2007-08-14

317

FOSSIL ANTHROPOIDS OF THE r y ALEMCAMBRIDGE INDIA  

E-print Network

; . ~ 1@'· t p t1tCO FOSSIL ANTHROPOIDS OF THE r y ALEMCAMBRIDGE INDIA EXPEDITION Q,F 1935 ? ~ -~~r J FOSSIL ANTHROPOIDS OF THE YALE-CAMBRIDGE INDIA EXPEDITION OF 1935 WILLIAM K. GREGORY MILO .. . .... . .. ... . . . . .. . .. . .... ...... . ..... . .. . ... .. . .. . .. ...... . ,, ·· following 27 1 #12;( FOSSIL ANTHROPOIDS OF THE YALE-CAMBRIDGE INDIA EXPEDITION OF 1935 INTRODUCTION The Yale

Boyer, Edmond

318

Correlations in fossil extinction and origination rates through geological time  

E-print Network

Correlations in fossil extinction and origination rates through geological time James W. Kirchner1, implying that the fossil record may be controlled by self-organized criticality or other scale-free internal dynamics of the biosphere. Here we directly test for correlations in the fossil record

Kirchner, James W.

319

The quality of the fossil record Michael J. Benton  

E-print Network

Chapter 4 The quality of the fossil record Michael J. Benton ABSTRACT Ever since the days of Charles Darwin, palaeontologists have been concerned about the quality of the fossil record. New concerns are often twice as old as the oldest fossils, and (2) the discovery that much of the variation in diversity

Benton, Michael

320

RESEARCH PAPER The first fossil record of Polyrhachis (Hymenoptera: Formicidae  

E-print Network

RESEARCH PAPER The first fossil record of Polyrhachis (Hymenoptera: Formicidae: Formicinae) from taxon represents the first occurrence of the genus in the fossil record. The origin and rise of one Á Polyrhachis Á New species Á Miocene Á Fossil ant Kurzfassung Aus dem Obermioza¨n von Kreta (Grie

Villemant, Claire

321

SURVEY OF SOCIAL INSECTS IN THE FOSSIL RECORD*  

E-print Network

SURVEY OF SOCIAL INSECTS IN THE FOSSIL RECORD* BY LAURIE BURNHAM Museum of Comparative Zoology the fossil record for clues not only on the antiquity of sociality, but also on the nature of these early recognized by Emerson (1955) have a fossil record extending at least as far back as the Tertiary. In 1967

Villemant, Claire

322

Fossil Papio Cranium From !Ncumtsa (Koanaka) Hills, Western Ngamiland, Botswana  

E-print Network

Fossil Papio Cranium From !Ncumtsa (Koanaka) Hills, Western Ngamiland, Botswana Blythe A. Williams cercopithecoid; baboon; Kalahari; Pleistocene ABSTRACT Three fossils, a cranium of Papio, a cer- copithecid crania of Papio are extremely rare in the fossil record outside of South Africa and because

323

Molecular timescales and the fossil record: a paleontological perspective  

Microsoft Academic Search

The fossil record serves a crucial function as an external calibration for genomic clocks and molecular evolutionary timescales. Although certain portions of the vertebrate fossil record are accurate, there is always uncertainty in establishing a divergence time because the fossils can only provide evidence of the first appearance of the descendants of a split, and by definition they underestimate the

Robert R. Reisz; Johannes Müller

2004-01-01

324

Identification of Common Fossil Organisms for Introductory Geology.  

ERIC Educational Resources Information Center

Provides a format for the identification of fossils when introducing geologic time in the laboratory. Presents an organization of fossils into three major groups based on radial, bilateral, and no apparent symmetry. States that this method reinforces student learning and provides for an orderly approach to fossils. (RT)

Davis, Larry Eugene; Eves, Robert Leo

1988-01-01

325

First Fossil Lamprey: A Record from the Pennsylvanian of Illinois  

Microsoft Academic Search

A fossil record of lampreys has previously been unknown. A new genus demonstrates the presence of this group in the Pennsylvanian. The body outline, parts of the head skeleton, rasping tongue mechanism, gill basket, and other internal organs are preserved. The fossils are very similar in structure to modern forms. The absence of hagfish characters in the fossil supports the

David Bardack; Rainer Zangerl

1968-01-01

326

Opportunism and competition in the non-fossil fuel obligation  

E-print Network

Opportunism and competition in the non-fossil fuel obligation Paolo Agnolucci July 2005 Tyndall are the responsibility of the author(s) alone and not the Tyndall Centre. #12;Summary The Non-Fossil Fuel Order (NFFO Electricity; Renewable Policy, Non-Fossil Fuel Obligation; Moral Hazard; Post-contractual Opportunism #12

Watson, Andrew

327

Carbon Capture by Fossil Fuel Power Plants: An Economic Analysis  

E-print Network

Carbon Capture by Fossil Fuel Power Plants: An Economic Analysis ¨Ozge I¸slegen Graduate School excellent research assistance. #12;Carbon Capture by Fossil Fuel Power Plants: An Economic Analysis Abstract: For fossil fuel power plants to be built in the future, carbon capture and storage (CCS) technologies offer

Silver, Whendee

328

Yankee Ticket Prices and Fossil Fuels 10 April 2008  

E-print Network

Yankee Ticket Prices and Fossil Fuels 10 April 2008 When I was young, Yankee Stadium had ~70 attention to this practice is that fossil fuel moguls are intent on hoodwinking the entire planet with an analogous scheme. The basic trick is this: fossil fuel reserves are overstated. Government "energy

Hansen, James E.

329

Reducing Fossil Carbon Emissions and Building Environmental Awareness at  

E-print Network

on the biophysical environment in the following ways: · Reducing the amount of fossil fuels that are consumed. · Reducing the amount of pollution that is generated from fossil fuel consumption. · Reducing the amount of waste that is created when extracting and consuming fossil fuels. · Reducing Dartmouth College's demand

330

Inferring natural selection in a fossil threespine stickleback  

Microsoft Academic Search

Inferring the causes for change in the fossil record has been a persistent problem in evo- lutionary biology. Three independent lines of evidence indicate that a lineage of the fossil stick- leback fish Gasterosteus doryssus experienced directional natural selection for reduction of armor. Nonetheless, application to this lineage of three methods to infer natural selection in the fossil record could

Michael A. Bell; Matthew P. Travis; D. Max Blouw

2006-01-01

331

METHODS TO REDUCE THE DEPENDENCE ON FOSSIL FUEL  

Microsoft Academic Search

SUMMARY The wealth level in the world is directly connected with energy use. Currently, fossil fuels provide the bulk of that energy. By definition, the availability of fossil fuel is finite. Moreover, there are strong indications that the CO2 emissions resulting from fossil fuel use have an effect on climates. Therefore, energy-efficient technologies and the use of sustainable energy should

Jacob Klimstra

332

FOSSIL RIDGE WILDERNESS STUDY AREA, COLORADO.  

USGS Publications Warehouse

The Fossil Ridge Wilderness Study Area, approximately 20 mi northeast of Gunnison in central Colorado, was studied and its mineral-resource potential assessed. Portions of the study area have substantiated resource potential for gold, silver, copper, lead, zinc, molybdenum, uranium, thorium, rare-earth elements, and high-calcium limestone. Much of the area has a probable resource potential for the preceeding commodities as well as for tin. Various other elements are found in anomalous concentrations within the study area, but there is likelihood for their occurrence in amounts sufficient to constitute resources. Exploration, especially for molybdenum, gold, and uranium, has been active in the past and is expected to continue in the future. No potential for fossil fuel resources was identified in this study.

DeWitt, Ed; Kluender, Steven E.

1984-01-01

333

Fossil energy waste management. Technology status report  

SciTech Connect

This report describes the current status and recent accomplishments of the Fossil Energy Waste Management (FE WM) projects sponsored by the Morgantown Energy Technology Center (METC) of the US Department of Energy (DOE). The primary goal of the Waste Management Program is to identify and develop optimal strategies to manage solid by-products from advanced coal technologies for the purpose of ensuring the competitiveness of advanced coal technologies as a future energy source. The projects in the Fossil Energy Waste Management Program are divided into three types of activities: Waste Characterization, Disposal Technologies, and Utilization Technologies. This technology status report includes a discussion on barriers to increased use of coal by-products. Also, the major technical and nontechnical challenges currently being addressed by the FE WM program are discussed. A bibliography of 96 citations and a list of project contacts is included if the reader is interested in obtaining additional information about the FE WM program.

Bossart, S.J.; Newman, D.A.

1995-02-01

334

Fossil Biodiversity: Red Noise Plus Signal  

E-print Network

We have examined the Fourier power spectrum as well as the Hurst exponent of extinction, origination, and total biodiversity in the marine fossil record, using a recently improved geologic timescale. We find all of them strongly inconsistent with past claims of self-similarity as well as inconsistent with random walk behavior. Instead, they are dominated by low-frequency power, with approximate f^-2 power over one decade in frequency. The spectrum turns over at about 10^5 y, lending plausibility to connections with galactic dynamics. Even in the background of this low-frequency dominance, a previously noted 62 My biodiversity cycle stands out with better than 99% confidence above the noise level, accounting for about 35% of the total variance in the fossil biodiversity record.

Melott, A L; Melott, Adrian L.; Lieberman, Bruce S.

2006-01-01

335

Fossil Biodiversity: Red Noise Plus Signal  

E-print Network

We have examined the Fourier power spectrum as well as the Hurst exponent of extinction, origination, and total biodiversity in the marine fossil record, using a recently improved geologic timescale. We find all of them strongly inconsistent with past claims of self-similarity as well as inconsistent with random walk behavior. Instead, they are dominated by low-frequency power, with approximate f^-2 power over one decade in frequency. The spectrum turns over at about 10^8 y, lending plausibility to connections with galactic dynamics. Even in the background of this low-frequency dominance, a previously noted 62 My biodiversity cycle stands out with better than 99% confidence above the noise level, accounting for about 35% of the total variance in the fossil biodiversity record.

Adrian L. Melott; Bruce S. Lieberman

2006-06-14

336

Structural coloration in a fossil feather.  

PubMed

Investigation of feathers from the famous Middle Eocene Messel Oil Shale near Darmstadt, Germany shows that they are preserved as arrays of fossilized melanosomes, the surrounding beta-keratin having degraded. The majority of feathers are preserved as aligned rod-shaped eumelanosomes. In some, however, the barbules of the open pennaceous, distal portion of the feather vane are preserved as a continuous external layer of closely packed melanosomes enclosing loosely aligned melanosomes. This arrangement is similar to the single thin-film nanostructure that generates an iridescent, structurally coloured sheen on the surface of black feathers in many lineages of living birds. This is, to our knowledge, the first evidence of preservation of a colour-producing nanostructure in a fossil feather and confirms the potential for determining colour differences in ancient birds and other dinosaurs. PMID:19710052

Vinther, Jakob; Briggs, Derek E G; Clarke, Julia; Mayr, Gerald; Prum, Richard O

2010-02-23

337

Structural coloration in a fossil feather  

PubMed Central

Investigation of feathers from the famous Middle Eocene Messel Oil Shale near Darmstadt, Germany shows that they are preserved as arrays of fossilized melanosomes, the surrounding beta-keratin having degraded. The majority of feathers are preserved as aligned rod-shaped eumelanosomes. In some, however, the barbules of the open pennaceous, distal portion of the feather vane are preserved as a continuous external layer of closely packed melanosomes enclosing loosely aligned melanosomes. This arrangement is similar to the single thin-film nanostructure that generates an iridescent, structurally coloured sheen on the surface of black feathers in many lineages of living birds. This is, to our knowledge, the first evidence of preservation of a colour-producing nanostructure in a fossil feather and confirms the potential for determining colour differences in ancient birds and other dinosaurs. PMID:19710052

Vinther, Jakob; Briggs, Derek E. G.; Clarke, Julia; Mayr, Gerald; Prum, Richard O.

2010-01-01

338

Oral Presentation of a Fossil Group  

NSDL National Science Digital Library

Each student chooses a different fossil group that interests him/her and prepares a 10 minute PowerPoint presentation about that group, lavishly illustrated and richly illuminated with fascinating facts! This can be as large a group as a phylum or as small as a species. Powerpoint handouts are given out during the oral presentation. Students must have a concluding slide citing references. The discussion must go beyond what is presented by the professor in lecture.

Max Reams

339

Fossil Record and Age of the Asteridae  

Microsoft Academic Search

The Asteridae is a group of some 80,000 species of flowering plants characterized by their fused corollas and iridoid compounds.\\u000a Recent phylogenetic analyses have helped delimit the group and have identified four main clades within it; Cornales, Ericales,\\u000a Lamiids and Campanulids, with the last two collectively known as the Euasteridae. A search for the oldest fossils representing\\u000a asterids yielded a

Marcela Martínez-Millán

2010-01-01

340

Identifying Fossil Bacteria in Martian Materials  

NASA Technical Reports Server (NTRS)

Within the next decade, robotic missions are going to Mars with the search for evidence for extant and extinct life as at least one of the mission objectives. Moreover, the first Martian samples will be returned to Earth in 2008. It is therefore imperative that we can be certain that we can identify life in Martian rocks. In this paper we will not be discussing extant life but will concentrate on fossil life.

Westall, F.; McKay, D. S.; Gibson, E. K., Jr.

1999-01-01

341

Adaptation, plant evolution, and the fossil record  

NASA Technical Reports Server (NTRS)

The importance of adaptation in determining patterns of evolution has become an important focus of debate in evolutionary biology. As it pertains to paleobotany, the issue is whether or not adaptive evolution mediated by natural selection is sufficient to explain the stratigraphic distributions of taxa and character states observed in the plant fossil record. One means of addressing this question is the functional evaluation of stratigraphic series of plant organs set in the context of paleoenvironmental change and temporal patterns of floral composition within environments. For certain organ systems, quantitative estimates of biophysical performance can be made on the basis of structures preserved in the fossil record. Performance estimates for plants separated in time or space can be compared directly. Implicit in different hypotheses of the forces that shape the evolutionary record (e.g. adaptation, mass extinction, rapid environmental change, chance) are predictions about stratigraphic and paleoenvironmental trends in the efficacy of functional performance. Existing data suggest that following the evolution of a significant structural innovation, adaptation for improved functional performance can be a major determinant of evolutionary changes in plants; however, there are structural and development limits to functional improvement, and once these are reached, the structure in question may no longer figure strongly in selection until and unless a new innovation evolves. The Silurian-Devonian paleobotanical record is consistent with the hypothesis that the succession of lowland floodplain dominants preserved in the fossil record of this interval was determined principally by the repeated evolution of new taxa that rose to ecological importance because of competitive advantages conferred by improved biophysical performance. This does not seem to be equally true for Carboniferous-Jurassic dominants of swamp and lowland floodplain environments. In these cases, environmental disruption appears to have been a major factor in shaping the fossil record. This does not mean that continuing adaptation was not important during this interval, but it may indicate that adaptive evolution was strongest in environments other than those best represented in the paleobotanical record.

Knoll, A. H.; Niklas, K. J.

1987-01-01

342

Fossil hominids from the Laetolil Beds  

Microsoft Academic Search

Remains of 13 early hominids have been found in the Laetolil Beds in northern Tanzania, 30 miles south of Olduvai Gorge. Potassium-argon dating of the fossiliferous deposits gives an upper limit averaging 3.59 Myr and a lower limit of 3.77 Myr. An extensive mammalian fauna is associated. The fossils occur in the upper 30 m of ash-fall and aeolian tuffs

M. D. Leakey; R. L. Hay; G. H. Curtis; R. E. Drake; M. K. Jackes

1976-01-01

343

Problematic microscopic trace (?) fossils, Oligocene, Slovakia  

NASA Astrophysics Data System (ADS)

Meioscopic to microscopic capsules found in reddish, probably marine or brackish shales (Oligocene, Pannonian Basin; South Slovakia) are interpreted as possible trace fossils. They may represent burrows of meioscopic in-fauna. Ferruginous walls of the capsules appeared very probably as late as during diagenesis; however, the (possibly organic) matrix had to exist before the diagenetic processes. Other discussed explanations (inorganic "ironstones"; coprolites) are not plausible.

Mikuláš, R.; Boorová, D.; Holcová, K.

2013-05-01

344

Fossil dust shells around luminous supergiants  

NASA Technical Reports Server (NTRS)

The observed frequency with which infrared excesses appear in F, G, and K supergiants of luminosity class Ia supports the idea that these excesses arise in a 'fossil' circumstellar dust shell that was formed during a prior M-super-giant phase of evolution. The required leftward evolution of the star on the H-R diagram would then imply that the Ledoux, rather than the Schwarzschild, criterion for convective mixing is the correct criterion to use in stellar evolution calculations.

Stothers, R.

1975-01-01

345

Precambrian ``fossil'' Vermiforma is a tectograph  

SciTech Connect

Vermiforma antiqua Cloud 1976, once celebrated as the earliest animal fossil of the US, is actually a tectonic artifact. The main argument is that the congruence and equal orientation of multiple patterns on the same bedding plane are incompatible with swaying worm bodies of worm burrows. As shown by analog and numerical simulations, these structures can be explained as tracks of particles that broke out from the base of an overlying turbidite and became rolled between beds during bed-to-bed shearing.

Seilacher, A.; Meschede, M.; Bolton, E.W.; Luginsland, H.

2000-03-01

346

Fossil pollen records of extant angiosperms  

Microsoft Academic Search

The fossil record for angiosperm pollen types which are comparable to recent taxa is evaluated, following a similar survey\\u000a published in 1970. Special attention is paid to the dating of the sediments. Evidence for 139 families is considered to be\\u000a reliable, for others the records are cited as provisional, pending the accumulation of more evidence. Some published records\\u000a are shown

Jan Muller

1981-01-01

347

U Pb dating of fossil enamel from the Swartkrans Pleistocene hominid site, South Africa  

NASA Astrophysics Data System (ADS)

We demonstrate that young fossil enamel older than the range of the U-series (˜ 300 ka) can be dated by the U-Pb methods using new models of U and Pb loss and uptake. Contrary to the current hypothesis of U uptake that only considers the adsorption/diffusion mechanism, we here develop a complete time-dependent model which takes gains and losses of the most critical nuclides ( 238U, 234U, and 230Th) into account, both during chemical (dissolved U) and physical (Th and U ?-recoil) processes. Lead is assumed to be a mixture between two components of common Pb and a radiogenic component; the proportions of these components are calculated from the Pb isotope abundances and U/Pb ratios. We apply this new U-Pb method to bovid enamel from the Swartkrans Cave (Gauteng Province, South Africa). This cave has yielded abundant early Pleistocene hominid remains attributed to Paranthropus and Homo as well as various associated archaeological vestiges. Biochronological comparisons with East Africa have provided age estimates ranging between 1.8 and 1.0 Ma, which, however, remain poorly constrained. After correction for initial 234U disequilibrium and further 238U loss, the U and Pb isotope data yield ages of 1.83 ± 1.38, 1.36 ± 0.29, and 0.83 ± 0.21 Ma for the three stratigraphic units, Members 1, 2, and 3, respectively. We discuss the consequences of these radiometric results for hominid evolution in South Africa.

Balter, Vincent; Blichert-Toft, Janne; Braga, José; Telouk, Philippe; Thackeray, Francis; Albarède, Francis

2008-03-01

348

Spatial Bias in the Marine Fossil Record  

PubMed Central

Inference of past and present global biodiversity requires enough global data to distinguish biological pattern from sampling artifact. Pertinently, many studies have exposed correlated relationships between richness and sampling in the fossil record, and methods to circumvent these biases have been proposed. Yet, these studies often ignore paleobiogeography, which is undeniably a critical component of ancient global diversity. Alarmingly, our global analysis of 481,613 marine fossils spread throughout the Phanerozoic reveals that where localities are and how intensively they have been sampled almost completely determines empirical spatial patterns of richness, suggesting no separation of biological pattern from sampling pattern. To overcome this, we analyze diversity using occurrence records drawn from two discrete paleolatitudinal bands which cover the bulk of the fossil data. After correcting the data for sampling bias, we find that these two bands have similar patterns of richness despite markedly different spatial coverage. Our findings suggest that i) long-term diversity trends result from large-scale tectonic evolution of the planet, ii) short-term diversity trends are region-specific, and iii) paleodiversity studies must constrain their analyses to well-sampled regions to uncover patterns not driven by sampling. PMID:24204570

Vilhena, Daril A.; Smith, Andrew B.

2013-01-01

349

The Undead: Fossil Galaxy Alive Again  

NASA Astrophysics Data System (ADS)

This project investigates the formation and evolution of fossil galaxies, specifically the history of active galactic nucleus (AGN) activity as it relates to galaxy mergers. We used low-frequency radio data from the J-VLA radio telescope's new P-band receivers [300-350MHz] to observe fossil galaxy J171811.93+563956.1 (referenced as FG30) at a red-shift of z=0.114. This galaxy was selected for its strong X-ray emission from the surrounding IGM, because it is indicative of an AGN. After cleaning and calibrating the data using CASA, images were generated to map the intensity of radio emission, revealing that FG30 is nearly a point source and lacks any prominent AGN jets. Analysis of the SDSS optical spectrum of FG30 revealed strong evidence of shocks. We believe that past AGN activity heated the intergalactic medium (IGM) to produce the strong X-ray emission, though the jets have been dormant for long enough that the IGM filled in the regions previously cleared by jets. The density of new material is now causing strong shocks when hit by newly restarted jets. This implies the start of a new epoch of AGN activity for FG30, which was most likely caused by a recent galaxy merger. This observation demonstrates that not all fossil groups have been quiescent, as the dominant theories suggested.*This work was supported by the National Science Foundation's REU program through NSF Award AST-1004881.

Berglund, Kallan; Wilcots, Eric M.

2015-01-01

350

Tool making, hand morphology and fossil hominins  

PubMed Central

Was stone tool making a factor in the evolution of human hand morphology? Is it possible to find evidence in fossil hominin hands for this capability? These questions are being addressed with increasingly sophisticated studies that are testing two hypotheses; (i) that humans have unique patterns of grip and hand movement capabilities compatible with effective stone tool making and use of the tools and, if this is the case, (ii) that there exist unique patterns of morphology in human hands that are consistent with these capabilities. Comparative analyses of human stone tool behaviours and chimpanzee feeding behaviours have revealed a distinctive set of forceful pinch grips by humans that are effective in the control of stones by one hand during manufacture and use of the tools. Comparative dissections, kinematic analyses and biomechanical studies indicate that humans do have a unique pattern of muscle architecture and joint surface form and functions consistent with the derived capabilities. A major remaining challenge is to identify skeletal features that reflect the full morphological pattern, and therefore may serve as clues to fossil hominin manipulative capabilities. Hominin fossils are evaluated for evidence of patterns of derived human grip and stress-accommodation features. PMID:24101624

Marzke, Mary W.

2013-01-01

351

Fossil avian eggshell preserves ancient DNA  

PubMed Central

Owing to exceptional biomolecule preservation, fossil avian eggshell has been used extensively in geochronology and palaeodietary studies. Here, we show, to our knowledge, for the first time that fossil eggshell is a previously unrecognized source of ancient DNA (aDNA). We describe the successful isolation and amplification of DNA from fossil eggshell up to 19 ka old. aDNA was successfully characterized from eggshell obtained from New Zealand (extinct moa and ducks), Madagascar (extinct elephant birds) and Australia (emu and owl). Our data demonstrate excellent preservation of the nucleic acids, evidenced by retrieval of both mitochondrial and nuclear DNA from many of the samples. Using confocal microscopy and quantitative PCR, this study critically evaluates approaches to maximize DNA recovery from powdered eggshell. Our quantitative PCR experiments also demonstrate that moa eggshell has approximately 125 times lower bacterial load than bone, making it a highly suitable substrate for high-throughput sequencing approaches. Importantly, the preservation of DNA in Pleistocene eggshell from Australia and Holocene deposits from Madagascar indicates that eggshell is an excellent substrate for the long-term preservation of DNA in warmer climates. The successful recovery of DNA from this substrate has implications in a number of scientific disciplines; most notably archaeology and palaeontology, where genotypes and/or DNA-based species identifications can add significantly to our understanding of diets, environments, past biodiversity and evolutionary processes. PMID:20219731

Oskam, Charlotte L.; Haile, James; McLay, Emma; Rigby, Paul; Allentoft, Morten E.; Olsen, Maia E.; Bengtsson, Camilla; Miller, Gifford H.; Schwenninger, Jean-Luc; Jacomb, Chris; Walter, Richard; Baynes, Alexander; Dortch, Joe; Parker-Pearson, Michael; Gilbert, M. Thomas P.; Holdaway, Richard N.; Willerslev, Eske; Bunce, Michael

2010-01-01

352

Age and metallicity gradients in fossil ellipticals  

NASA Astrophysics Data System (ADS)

Context. Fossil galaxy groups are speculated to be old and highly evolved systems of galaxies that formed early in the universe and had enough time to deplete their L? galaxies through successive mergers of member galaxies, building up one massive central elliptical, but retaining the group X-ray halo. Aims: Considering that fossils are the remnants of mergers in ordinary groups, the merger history of the progenitor group is expected to be imprinted in the fossil central galaxy (FCG). We present for the first time radial gradients of single-stellar population (SSP) ages and metallicites in a sample of FCGs to constrain their formation scenario. We also measure line-strength gradients for the strongest absorption features in these galaxies. Methods: We took deep spectra with the long-slit spectrograph ISIS at the William Herschel Telescope (WHT) for six FCGs. The obtained spectra are fit with Pegase HR SSP models within the full-spectrum fitting package ULySS yielding SSP ages and metallicities of the stellar populations. We measure radial gradients of SSP ages and metallicities along the major axes. Lick indices are measured for the strongest absorption features to determine line-strength gradients and compare with the full-spectrum fitting results. Results: Our sample comprises some of the most massive galaxies in the universe exhibiting an average central velocity dispersion of ?0 = 271 ± 28 km s-1. Metallicity gradients are throughout negative with comparatively flat slopes of ?[Fe/H] = -0.19 ± 0.08 while age gradients are found to be insignificant (?age = 0.00 ± 0.05). All FCGs lie on the fundamental plane, suggesting that they are virialised systems. We find that gradient strengths and central metallicities are similar to those found in cluster ellipticals of similar mass. Conclusions: The comparatively flat metallicity gradients with respect to those predicted by monolithic collapse (?Z = -0.5) suggest that fossils are indeed the result of multiple major mergers. Hence we conclude that fossils are not "failed groups" that formed with a top-heavy luminosity function. The low scatter of gradient slopes suggests a similar merging history for all galaxies in our sample. Figures 3 and 4 are available in electronic form at http://www.aanda.orgReduced spectra are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/553/A99

Eigenthaler, P.; Zeilinger, W. W.

2013-05-01

353

Fossil Groups Origins III. Characterization of the sample and observational properties of fossil systems  

E-print Network

(Abridged) Fossil systems are group- or cluster-sized objects whose luminosity is dominated by a very massive central galaxy. In the current cold dark matter scenario, these objects formed hierarchically at an early epoch of the Universe and then slowly evolved until present day. That is the reason why they are called {\\it fossils}. We started an extensive observational program to characterize a sample of 34 fossil group candidates spanning a broad range of physical properties. Deep $r-$band images were taken for each candidate and optical spectroscopic observations were obtained for $\\sim$ 1200 galaxies. This new dataset was completed with SDSS DR7 archival data to obtain robust cluster membership and global properties of each fossil group candidate. For each system, we recomputed the magnitude gaps between the two brightest galaxies ($\\Delta m_{12}$) and the first and fourth ranked galaxies ($\\Delta m_{14}$) within 0.5 $R_{{\\rm 200}}$. We consider fossil systems those with $\\Delta m_{12} \\ge 2$ mag or $\\Del...

Zarattini, S; Girardi, M; Castro-Rodriguez, N; Boschin, W; Aguerri, J A L; Méndez-Abreu, J; Sánchez-Janssen, R; Catalán-Torrecilla, C; Corsini, E M; del Burgo, C; D'Onghia, E; Herrera-Ruiz, N; Iglesias-Páramo, J; Bailon, E Jimenez; Muñoz, M Lozada; Napolitano, N; Vilchez, J M

2014-01-01

354

Who Was Helping? The Scope for Female Cooperative Breeding in Early Homo  

PubMed Central

Derived aspects of our human life history, such as short interbirth intervals and altricial newborns, have been attributed to male provisioning of nutrient-rich meat within monogamous relationships. However, many primatologists and anthropologists have questioned the relative importance of pair-bonding and biparental care, pointing to evidence that cooperative breeding better characterizes human reproductive and child-care relationships. We present a mathematical model with empirically-informed parameter ranges showing that natural selection favors cooperation among mothers over a wide range of conditions. In contrast, our analysis provides a far more narrow range of support for selection favoring male coalition-based monogamy over more promiscuous independent males, suggesting that provisioning within monogamous relationships may fall short of explaining the evolution of Homo life history. Rather, broader cooperative networks within and between the sexes provide the primary basis for our unique life history. PMID:24367605

Bell, Adrian Viliami; Hinde, Katie; Newson, Lesley

2013-01-01

355

Antihormonal potential of selected D-homo and D-seco estratriene derivatives.  

PubMed

Since many estrogen derivatives exhibit anti-hormone or enzyme inhibition potential, a large number of steroidal derivatives have been synthesised from appropriate precursors, in order to obtain potential therapeutics for the treatment of hormone-dependent cancers. In molecular docking studies, based on X-ray crystallographic analysis, selected D-homo and D-seco estratriene derivatives were predicted to bind strongly to estrogen receptor ? (ER?), aromatase and 17,20 lyase, suggesting they could be good starting compounds for antihormonal studies. Test results in vivo suggest that these compounds do not possess estrogenic activity, while some of them showed weak anti-estrogenic properties. In vitro anti-aromatase and anti-lyase assays showed partial inhibition of these two enzymes, while some compounds activated aromatase. Aromatase activators are capable of promoting estrogen synthesis for treatment of pathological conditions caused by estrogen depletion, e.g. osteopenia or osteoporosis. PMID:25204595

Jovanovi?-Šanta, Suzana S; Petri, Edward T; Klisuri?, Olivera R; Szécsi, Mihály; Kova?evi?, Radmila; Petrovi?, Julijana A

2014-09-01

356

Syntheses and antiproliferative effects of d-homo- and d-secoestrones.  

PubMed

Substituted and/or heterocyclic d-homoestrone derivatives were synthetized via the intramolecular cyclization of a ?-alkenyl-d-secoaldehyde, -d-secoalcohol or -d-secocarboxylic acid of estrone 3-benzyl ether. The d-secoalcohol was modified at three sites in the molecule. The in vitro antiproliferative activities of the new d-homo- and d-secoestrone derivatives were determined on HeLa, MCF-7, A431 and A2780 cells through use of MTT assay. d-Homoalcohols 3 and 5 displayed cell line-selective cytostatic effects against ovarian and cervical cell lines, respectively. Two d-secoestrones (6 and 12c) proved to be effective, with IC50 values comparable with those of the reference agent cisplatin. A selected compound (6) was tested by tubulin polymerization assay and its cancer specificity was additionally determined by using noncancerous human fibroblast cells. PMID:24928727

Mernyák, Erzsébet; Szabó, Johanna; Bacsa, Ildikó; Huber, Judit; Schneider, Gyula; Minorics, Renáta; Bózsity, Noémi; Zupkó, István; Varga, Mónika; Bikádi, Zsolt; Hazai, Eszter; Wölfling, János

2014-09-01

357

Efficiency of Resonance Energy Transfer in Homo-Oligomeric Complexes of Proteins  

PubMed Central

A theoretical model is proposed for the apparent efficiency of fluorescence (Förster) resonance energy transfer (FRET) in mixtures of free monomers and homo-oligomeric protein complexes of uniform size. The model takes into account possible pathways for transfer of optical excitations from single donors to multiple acceptors and from multiple donors (non-simultaneously) to single acceptors. This necessary departure from the standard theory has been suggested in the literature, but it has only been successfully implemented for a few particular cases, such as for particular geometries of the oligomers. The predictions of the present theoretical model differ significantly from those of the standard theory, with the exception of the case of dimers, for which agreement is observed. This model therefore provides new insights into the FRET behavior of oligomers comprising more than two monomers, and also suggests means for determining the size of oligomeric protein complexes as well as the proportion of associated and unassociated monomers. PMID:19669544

2007-01-01

358

Fossil Energy Program semiannual progress report, October 1990--March 1991  

SciTech Connect

This report covers progress made during the period October 1, 1990, through March 31, 1991, for research and development projects that contribute to the advancement of various fossil energy technologies. Projects on the Fossil Energy Program are supported by the DOE Office of Fossil Energy, the DOE Morgantown Energy Technology Center, the DOE Pittsburgh Energy Technology Center, the DOE Fossil Energy Clean Coal Technology Program, the DOE Office of Basic Energy Sciences, the DOE Fossil Energy Office of Petroleum Reserves, the DOE Fossil Energy Naval Petroleum and Oil Shale Reserves, and the US Agency for International Development. The Fossil, Energy Program organization chart is shown in the appendix. Topics include: alloys, ceramics and composite research and development; corrosion and erosion research; environmental analysis and information systems; coal conversion development; mild gasification product characterization; coal combustion research; strategic petroleum reserve planning and modeling; and coal structure and chemistry.

Judkins, R.R.

1992-07-01

359

Designed aromatic homo-dipeptides: formation of ordered nanostructures and potential nanotechnological applications.  

PubMed

Molecular self-assembly offers new routes for the fabrication of novel materials at the nano-scale. Peptide-based nanostructures represent nano-objects of particular interest, as they are biocompatible, can be easily synthesized in large amounts, can be decorated with functional elements and can be used in various biological and non-biological applications. We had previously revealed the formation of highly ordered tubular structures by the diphenylalanine peptide, the core recognition motif of Alzheimer's beta-amyloid polypeptide, due to specific aromatic interactions. We further confirmed this model and demonstrated that a non-charged peptide analogue, Ac-Phe-Phe-NH2, self-assembled into similar tubular structures. We later explored other amine and carboxyl modified diphenylalanine peptide analogues and revealed that these dipeptides can form ordered tubular structures at the nanometric scale. Moreover, a very similar peptide, the diphenylglycine, self-assembled into ordered nano-spherical assemblies. Here we extend our research and explore the self-assembly of other homo-aromatic dipeptides in which their phenyl side-chains are modified with halogen atoms (di-para-fluoro-Phe, di-pentafluoro-Phe, di-para-iodo-Phe), additional phenyl groups (di-4-phenyl-Phe), or with nitro substitutions (di-para-nitro-Phe). We also probed the effect of the alteration of the phenyl groups with naphtyl groups (di-D-1-Nal and di-D-2-Nal). In all cases, well-ordered nanostructures were obtained and studied by scanning electron microscopy, transmission electron microscopy and vibrational spectroscopy. Taken together, the current work and previous ones define the homo-aromatic dipeptide as a central motif for the formation of ordered self-assembled tubular, spherical and two-dimensional structures at the nano-scale. PMID:16582461

Reches, Meital; Gazit, Ehud

2006-03-01

360

Non-growth-associated demethylation of dimethylsulfoniopropionate by (homo)acetogenic bacteria.  

PubMed

The demethylation of the algal osmolyte dimethylsulfoniopropionate (DMSP) to methylthiopropionate (MTPA) by (homo)acetogenic bacteria was studied. Five Eubacterium limosum strains (including the type strain), Sporomusa ovata DSM 2662(T), Sporomusa sphaeroides DSM 2875(T), and Acetobacterium woodii DSM 1030(T) were shown to demethylate DMSP stoichiometrically to MTPA. The (homo)acetogenic fermentation based on this demethylation did not result in any significant increase in biomass. The analogous demethylation of glycine betaine to dimethylglycine does support growth of acetogens. In batch cultures of E. limosum PM31 DMSP and glycine betaine were demethylated simultaneously. In mixed substrates experiments with fructose-DMSP or methanol-DMSP, DMSP was used rapidly but only after exhaustion of the fructose or the methanol. In steady-state fructose-limited chemostat cultures (at a dilution rate of 0.03 h(-1)) with DMSP as a second reservoir substrate, DMSP was biotransformed to MTPA but this did not result in higher biomass values than in cultures without DMSP; cells from such cultures demethylated DMSP at rates of approximately 50 nmol min(-1) mg of protein(-1), both after growth in the presence of DMSP and after growth in its absence. In cell extracts of glycine betaine-grown strain PM31, DMSP demethylation activities of 21 to 24 nmol min(-1) mg of protein(-1) were detected with tetrahydrofolate as a methyl acceptor; the activities seen with glycine betaine were approximately 10-fold lower. A speculative explanation for the demethylation of DMSP without an obvious benefit for the organism is that the DMSP-demethylating activity is catalyzed by the glycine betaine-demethylating enzyme and that a transport-related factor, in particular a higher energy demand for DMSP transport across the cytoplasmic membrane than for glycine betaine transport, may reduce the overall ATP yield of the fermentation to virtually zero. PMID:11133459

Jansen, M; Hansen, T A

2001-01-01

361

Azole Affinity of Sterol 14?-Demethylase (CYP51) Enzymes from Candida albicans and Homo sapiens  

PubMed Central

Candida albicans CYP51 (CaCYP51) (Erg11), full-length Homo sapiens CYP51 (HsCYP51), and truncated ?60HsCYP51 were expressed in Escherichia coli and purified to homogeneity. CaCYP51 and both HsCYP51 enzymes bound lanosterol (Ks, 14 to 18 ?M) and catalyzed the 14?-demethylation of lanosterol using Homo sapiens cytochrome P450 reductase and NADPH as redox partners. Both HsCYP51 enzymes bound clotrimazole, itraconazole, and ketoconazole tightly (dissociation constants [Kds], 42 to 131 nM) but bound fluconazole (Kd, ?30,500 nM) and voriconazole (Kd, ?2,300 nM) weakly, whereas CaCYP51 bound all five medical azole drugs tightly (Kds, 10 to 56 nM). Selectivity for CaCYP51 over HsCYP51 ranged from 2-fold (clotrimazole) to 540-fold (fluconazole) among the medical azoles. In contrast, selectivity for CaCYP51 over ?60HsCYP51 with agricultural azoles ranged from 3-fold (tebuconazole) to 9-fold (propiconazole). Prothioconazole bound extremely weakly to CaCYP51 and ?60HsCYP51, producing atypical type I UV-visible difference spectra (Kds, 6,100 and 910 nM, respectively), indicating that binding was not accomplished through direct coordination with the heme ferric ion. Prothioconazole-desthio (the intracellular derivative of prothioconazole) bound tightly to both CaCYP51 and ?60HsCYP51 (Kd, ?40 nM). These differences in binding affinities were reflected in the observed 50% inhibitory concentration (IC50) values, which were 9- to 2,000-fold higher for ?60HsCYP51 than for CaCYP51, with the exception of tebuconazole, which strongly inhibited both CYP51 enzymes. In contrast, prothioconazole weakly inhibited CaCYP51 (IC50, ?150 ?M) and did not significantly inhibit ?60HsCYP51. PMID:23274672

Warrilow, Andrew G.; Parker, Josie E.; Kelly, Diane E.

2013-01-01

362

Zinc finger protein 131 inhibits estrogen signaling by suppressing estrogen receptor {alpha} homo-dimerization  

SciTech Connect

Highlights: Black-Right-Pointing-Pointer ZNF131 directly interacts with ER{alpha}. Black-Right-Pointing-Pointer The binding affinity of ZNF131 to ER{alpha} increases upon E2 stimulation. Black-Right-Pointing-Pointer ZNF131 inhibits ER{alpha}-mediated trans-activation by suppressing its homo-dimerization. Black-Right-Pointing-Pointer ZNF131 inhibits ER{alpha}-dimerization and E2-induced breast cancer cell proliferation. Black-Right-Pointing-Pointer ZNF131 inhibits estrogen signaling by acting as an ER{alpha}-co-repressor. -- Abstract: Steroid hormone estrogen elicits various physiological functions, many of which are mediated through two structurally and functionally distinct estrogen receptors, ER{alpha} and ER{beta}. The functional role of zinc finger protein 131 (ZNF131) is poorly understood, but it is assumed to possess transcriptional regulation activity due to the presence of a DNA binding motif. A few recent reports, including ours, revealed that ZNF131 acts as a negative regulator of ER{alpha} and that SUMO modification potentiates the negative effect of ZNF131 on estrogen signaling. However, its molecular mechanism for ER{alpha} inhibition has not been elucidated in detail. Here, we demonstrate that ZNF131 directly interacts with ER{alpha}, which consequently inhibits ER{alpha}-mediated trans-activation by suppressing its homo-dimerization. Moreover, we show that the C-terminal region of ZNF131 containing the SUMOylation site is necessary for its inhibition of estrogen signaling. Taken together, these data suggest that ZNF131 inhibits estrogen signaling by acting as an ER{alpha}-co-repressor.

Oh, Yohan [Department of Systems Biology, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749 (Korea, Republic of)] [Department of Systems Biology, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749 (Korea, Republic of); Chung, Kwang Chul, E-mail: kchung@yonsei.ac.kr [Department of Systems Biology, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749 (Korea, Republic of)

2013-01-04

363

Identification and functional impact of homo-oligomers of the human proton-coupled folate transporter.  

PubMed

The proton-coupled folate transporter (PCFT; SLC46A1) is a proton-folate symporter that is abundantly expressed in solid tumors and normal tissues, such as duodenum. The acidic pH optimum for PCFT is relevant to intestinal absorption of folates and could afford a means of selectively targeting tumors with novel cytotoxic antifolates. PCFT is a member of the major facilitator superfamily of transporters. Because major facilitator superfamily members exist as homo-oligomers, we tested this for PCFT because such structures could be significant to PCFT mechanism and regulation. By transiently expressing PCFT in reduced folate carrier- and PCFT-null HeLa (R1-11) cells and chemical cross-linking with 1,1-methanediyl bismethanethiosulfonate and Western blotting, PCFT species with molecular masses approximating those of the PCFT dimer and higher order oligomers were detected. Blue native polyacrylamide gel electrophoresis identified PCFT dimer, trimer, and tetramer forms. PCFT monomers with hemagglutinin and His(10) epitope tags were co-expressed in R1-11 cells, solubilized, and bound to nickel affinity columns, establishing their physical associations. Co-expressing YPet and ECFP*-tagged PCFT monomers enabled transport and fluorescence resonance energy transfer in plasma membranes of R1-11 cells. Combined wild-type (WT) and inactive mutant P425R PCFTs were targeted to the cell surface by surface biotinylation/Western blots and confocal microscopy and functionally exhibited a "dominant-positive" phenotype, implying positive cooperativity between PCFT monomers and functional rescue of mutant by WT PCFT. Our results demonstrate the existence of PCFT homo-oligomers and imply their functional and regulatory impact. Better understanding of these higher order PCFT structures may lead to therapeutic applications related to folate uptake in hereditary folate malabsorption, and delivery of PCFT-targeted chemotherapy drugs for cancer. PMID:22179615

Hou, Zhanjun; Kugel Desmoulin, Sita; Etnyre, Erika; Olive, Mary; Hsiung, Benjamin; Cherian, Christina; Wloszczynski, Patrick A; Moin, Kamiar; Matherly, Larry H

2012-02-10

364

Identification and Functional Impact of Homo-oligomers of the Human Proton-coupled Folate Transporter*  

PubMed Central

The proton-coupled folate transporter (PCFT; SLC46A1) is a proton-folate symporter that is abundantly expressed in solid tumors and normal tissues, such as duodenum. The acidic pH optimum for PCFT is relevant to intestinal absorption of folates and could afford a means of selectively targeting tumors with novel cytotoxic antifolates. PCFT is a member of the major facilitator superfamily of transporters. Because major facilitator superfamily members exist as homo-oligomers, we tested this for PCFT because such structures could be significant to PCFT mechanism and regulation. By transiently expressing PCFT in reduced folate carrier- and PCFT-null HeLa (R1-11) cells and chemical cross-linking with 1,1-methanediyl bismethanethiosulfonate and Western blotting, PCFT species with molecular masses approximating those of the PCFT dimer and higher order oligomers were detected. Blue native polyacrylamide gel electrophoresis identified PCFT dimer, trimer, and tetramer forms. PCFT monomers with hemagglutinin and His10 epitope tags were co-expressed in R1-11 cells, solubilized, and bound to nickel affinity columns, establishing their physical associations. Co-expressing YPet and ECFP*-tagged PCFT monomers enabled transport and fluorescence resonance energy transfer in plasma membranes of R1-11 cells. Combined wild-type (WT) and inactive mutant P425R PCFTs were targeted to the cell surface by surface biotinylation/Western blots and confocal microscopy and functionally exhibited a “dominant-positive” phenotype, implying positive cooperativity between PCFT monomers and functional rescue of mutant by WT PCFT. Our results demonstrate the existence of PCFT homo-oligomers and imply their functional and regulatory impact. Better understanding of these higher order PCFT structures may lead to therapeutic applications related to folate uptake in hereditary folate malabsorption, and delivery of PCFT-targeted chemotherapy drugs for cancer. PMID:22179615

Hou, Zhanjun; Kugel Desmoulin, Sita; Etnyre, Erika; Olive, Mary; Hsiung, Benjamin; Cherian, Christina; Wloszczynski, Patrick A.; Moin, Kamiar; Matherly, Larry H.

2012-01-01

365

Molecular biology of Homo sapiens: Abstracts of papers presented at the 51st Cold Spring Harbor symposium on quantitative biology  

SciTech Connect

This volume contains abstracts of papers presented at the 51st Cold Springs Harbor Symposium on Quantitative Biology. The topic for this meeting was the ''Molecular Biology of Homo sapiens.'' Sessions were entitled Human Gene Map, Human Cancer Genes, Genetic Diagnosis, Human Evolution, Drugs Made Off Human Genes, Receptors, and Gene Therapy. (DT)

Watson, J.D.; Siniscalco, M.

1986-01-01

366

Superconductivity of domain walls in the ferromagnet HoMo6S8 J. L. Genicon, B. Laaboudi, R. Tournier  

E-print Network

1079 Superconductivity of domain walls in the ferromagnet HoMo6S8 J. L. Genicon, B. Laaboudi, R and on the resistance. We believe that these results can be related to some superconductivity inside domain walls existence of superconductivity in ferro- magnetic compounds has been discussed in the past. Ginzburg [1

Boyer, Edmond

367

Homo-and hetero-interactions between air bubbles and oil droplets measured by atomic force microscopy  

E-print Network

velocities, it is seen that deformation of the bodies and lubrication in the film generated between them can) theory, developed originally to understand the stability of dispersions of solid particles. For homo objects with quantitative precision, whereby lubrication in the thin aqueous film between the interacting

Chan, Derek Y C

368

Both Homo and Heterodimers of Marek's Disease Virus Encoded Meq Protein Contribute to Transformation of Lymphocytes in Chickens  

Technology Transfer Automated Retrieval System (TEKTRAN)

Marek’s disease virus (MDV) elicits T-cell lymphomas in chickens. The MDV genome encodes an oncoprotein, Meq, with similarity to the Jun/Fos family of proteins. Similar to Jun, the leucine zipper region of Meq allows the formation of homo- and heterodimers. We have previously shown that Meq homodime...

369

Yeast fermentation affected by homo- and hetero-fermentative Lactobacilli isolated from fuel ethanol distilleries with sugarcane products as substrates  

Technology Transfer Automated Retrieval System (TEKTRAN)

The antagonism between by yeast and lactobacilli is largely dependent on the initial population of each organism. While homo-fermentative lactobacillus present higher inhibitory effect upon yeast when in equal cell number, in industrial fuel ethanol conditions where high yeast cell densities prevail...

370

In situ growth and density-functional-theory study of polarity-dependent homo-epitaxial ZnO microwires  

SciTech Connect

Polarity-dependent homo-epitaxy on (0001)-Zn and (0001)-O surfaces of cleaved ZnO microwires was investigated by in situ growth in ESEMand DFT simulations. ZnO monomers adsorption, adatoms desorption and chemisorption were simulated to understand the explicit mechanism.

Zhu, Rui [ORNL; Xu, Jun [ORNL; Gao, Jingyun [Peking University; Zhang, Jingmin [Peking University; Zhu, Wenguang [University of Tennessee, Knoxville (UTK); Xu, Hongjun [Peking University; Sun, Yanghui [Peking University; Fu, Qiang [Peking University; Chen, Li [Peking University; Du, Dapeng [Peking University

2012-01-01

371

TREE vol. 5, no. II, November 1990 Paleoanthropology Today  

E-print Network

chapters give similar coverage to the Neanderthals of earlier Late Pleistocene Europe and the Near East populations of Homo erectus evolved locally into H. sapiens (e.g. Neanderthals in Europe), to be replaced

Delson, Eric

372

102 SCIENTIFIC AMERICAN JANUARY 2005 ILLUSTRATIONBYMATTCOLLINS;PHOTOGRAPHBYFRANKVERONSKY  

E-print Network

- couraged the downsizing of a stray group of Homo erectus who wound up there. Small stature was selected from stiff guys dressed in cheap suits particularly disturbs me, but that's probably because I was just

Fiser, József

373

Comparative evaluation of solar, fission, fusion, and fossil energy resources. Part 4: Energy from fossil fuels  

NASA Technical Reports Server (NTRS)

The conversion of fossil-fired power plants now burning oil or gas to burn coal is discussed along with the relaxation of air quality standards and the development of coal gasification processes to insure a continued supply of gas from coal. The location of oil fields, refining areas, natural gas fields, and pipelines in the U.S. is shown. The technologies of modern fossil-fired boilers and gas turbines are defined along with the new technologies of fluid-bed boilers and MHD generators.

Williams, J. R.

1974-01-01

374

A new small-bodied hominin from the Late Pleistocene of Flores, Indonesia  

Microsoft Academic Search

Currently, it is widely accepted that only one hominin genus, Homo, was present in Pleistocene Asia, represented by two species, Homo erectus and Homo sapiens. Both species are characterized by greater brain size, increased body height and smaller teeth relative to Pliocene Australopithecus in Africa. Here we report the discovery, from the Late Pleistocene of Flores, Indonesia, of an adult

T. Sutikna; M. J. Morwood; R. P. Soejono; Jatmiko; E. Wayhu Saptomo; Rokus Awe Due; P. Brown

2004-01-01

375

Neoproterozoic glaciations and the fossil record  

NASA Astrophysics Data System (ADS)

Sedimentary, geochronological, and ?13C chemostratigraphic data require that at least three glaciations—the Sturtian, Marinoan, and Gaskiers in geochronological order—occurred in the Neoproterozoic glacial interval (NGI; ca. 750-580 Ma); at least the Gaskiers glaciation has not been demonstrated global in nature. Available radiometric and ?13C chemostratigraphic data also suggest that the fossil-rich Doushantuo Formation may have been deposited after the Marinoan but before the Gaskiers glaciation, thus representing a window between two glaciations. A review of the fossil record under this geochronological framework reveals the following patterns: 1) a broad decline in stromatolites and acritarchs occurred in the Cryogenian (ca. 750-600 Ma); 2) a taxonomically unique assemblage of large acanthomorphic acritarchs occurs between the Marinoan and Gaskiers glaciations; 3) multicellular algae diversified after the Marinoan glaciation, although they evolved earlier; 4) animals, probably in microscopic forms, evolved before the Gaskiers glaciation if not earlier; and 5) post-Gaskiers diversification of complex Ediacaran organisms/animals may have begun in deep-water slope environments and later expanded to shallow-water shelf environments where macrobilaterians and biomineralized animals first appeared. It is hypothesized that 1) the Cryogenian decline in stromatolites and acritarchs may have been causally related to glaciations; and 2) acanthomorphic acritarchs, algae, and animals may have suffered diversity loss related to the Gaskiers glaciation. The fossil record also implies that 1) at least some lineages of different algal clades survived all Neoproterozoic glaciations; and 2) some members of the animal clade survived the Gaskiers glaciation, probably in non-glaciated refiigia.

Xiao, Shuhai

376

The Quaternary fossil-pollen record and global change  

SciTech Connect

Fossil pollen provide one of the most valuable records of vegetation and climate change during the recent geological past. Advantages of the fossil-pollen record are that deposits containing fossil pollen are widespread, especially in areas having natural lakes, that fossil pollen occurs in continuous stratigraphic sequences spanning millennia, and that fossil pollen occurs in quantitative assemblages permitting a multivariate approach for reconstructing past vegetation and climates. Because of stratigraphic continuity, fossil pollen records climate cycles on a wide range of scales, from annual to the 100 ka Milankovitch cycles. Receiving particular emphasis recently are decadal to century scale changes, possible from the sediments of varved lakes, and late Pleistocene events on a 5--10 ka scale possibly correlating with the Heinrich events in the North Atlantic marine record or the Dansgaard-Oeschger events in the Greenland ice-core record. Researchers have long reconstructed vegetation and climate by qualitative interpretation of the fossil-pollen record. Recently quantitative interpretation has developed with the aid of large fossil-pollen databases and sophisticated numerical models. In addition, fossil pollen are important climate proxy data for validating General Circulation Models, which are used for predicting the possible magnitude future climate change. Fossil-pollen data also contribute to an understanding of ecological issues associated with global climate change, including questions of how and how rapidly ecosystems might respond to abrupt climate change.

Grimm, E.C. (Illinois State Museum, Springfield, IL (United States). Research and Collections Center)

1993-03-01

377

Comparing amber fossil assemblages across the Cenozoic.  

PubMed

To justify faunistic comparisons of ambers that differ botanically, geographically and by age, we need to determine that resins sampled uniformly. Our pluralistic approach, analysing size distributions of 671 fossilized spider species from different behavioural guilds, demonstrates that ecological information about the communities of two well-studied ambers is retained. Several lines of evidence show that greater structural complexity of Baltic compared to Dominican amber trees explains the presence of larger web-spinners. No size differences occur in active hunters. Consequently, we demonstrate for the first time that resins were trapping organisms uniformly and that comparisons of amber palaeoecosystem structure across deep time are possible. PMID:17148379

Penney, David; Langan, A Mark

2006-06-22

378

Molecules, fossils, and the origin of tetrapods.  

PubMed

Since the discovery of the coelacanth, Latimeria chalumnae, more than 50 years ago, paleontologists and comparative morphologists have debated whether coelacanths or lungfishes, two groups of lobe-finned fishes, are the closest living relatives of land vertebrates (Tetrapoda). Previously, Meyer and Wilson (1990) determined partial DNA sequences from two conservative mitochondrial genes and found support for a close relationship of lungfishes to tetrapods. We present additional DNA sequences from the 12S rRNA mitochondrial gene for three species of the two lineages of lungfishes that were not represented in the first study: Protopterus annectens and Protopterus aethiopicus from Africa and Neoceratodus forsteri (kindly provided by B. Hedges and L. Maxson) from Australia. This extended data set tends to group the two lepidosirenid lungfish lineages (Lepidosiren and Protopterus) with Neoceratodus as their sister group. All lungfishes seem to be more closely related to tetrapods than the coelacanth is. This result appears to rule out the possibility that the coelacanth lineage gave rise to land vertebrates. The common ancestor of lungfishes and tetrapods might have possessed multiple morphological traits that are shared by lungfishes and tetrapods [Meyer and Wilson (1990) listed 14 such traits]. Those traits that seem to link Latimeria and tetrapods are arguably due to convergent evolution or reversals and not to common descent. In this way, the molecular tree facilitates an evolutionary interpretation of the morphological differences among the living forms. We recommended that the extinct groups of lobe-finned fishes be placed onto the molecular tree that has lungfishes and not the coelacanth more closely related to tetrapods. The placement of fossils would help to further interpret the sequence of morphological events and innovations associated with the origin of tetrapods but appears to be problematic because the quality of fossils is not always high enough, and differences among paleontologists in the interpretation of the fossils have stood in the way of a consensus opinion for the branching order among lobefinned fishes. Marshall and Schultze (1992) criticized the morphological analysis presented by Meyer and Wilson (1990) and suggest that 13 of the 14 morphological traits that support the sister group relationship of lungfishes and tetrapods are not shared derived characters. Here we present further alternative viewpoints to the ones of Marshall and Schultze (1992) from the paleontological literature. We argue that all available information (paleontological, neontological, and molecular data) and rigorous cladistic methodology should be used when relating fossils and extant taxa in a phylogenetic framework. PMID:1501250

Meyer, A; Dolven, S I

1992-08-01

379

Comparing amber fossil assemblages across the Cenozoic  

PubMed Central

To justify faunistic comparisons of ambers that differ botanically, geographically and by age, we need to determine that resins sampled uniformly. Our pluralistic approach, analysing size distributions of 671 fossilized spider species from different behavioural guilds, demonstrates that ecological information about the communities of two well-studied ambers is retained. Several lines of evidence show that greater structural complexity of Baltic compared to Dominican amber trees explains the presence of larger web-spinners. No size differences occur in active hunters. Consequently, we demonstrate for the first time that resins were trapping organisms uniformly and that comparisons of amber palaeoecosystem structure across deep time are possible. PMID:17148379

Penney, David; Langan, A. Mark

2006-01-01

380

What Can You Learn From Fossils?  

NSDL National Science Digital Library

At one point or another, it seems like all students are interested in paleontology. Wonderful extinct animals like dinosaurs excite the imagination like almost nothing else. Once you have the students' interest, you will find that a study of paleontology provides avenues of exploration into a wide variety of foundational sciences such as biology, geology, chemistry, physics, and astronomy. The purpose of this set of activities is to enable students to engage in the same kind of investigative study as do paleontologists. Included in this free selection from Adventures in Paleontology: 36 Classroom Fossil Activities are nine lessons and corresponding activities. You will also find included, a Table of Contents, Introduction, and Index.

Slesnick, Irwin; Hansen, Thor

2006-01-01

381

Modeling of advanced fossil fuel power plants  

NASA Astrophysics Data System (ADS)

The first part of this thesis deals with greenhouse gas (GHG) emissions from fossil fuel-fired power stations. The GHG emission estimation from fossil fuel power generation industry signifies that emissions from this industry can be significantly reduced by fuel switching and adaption of advanced power generation technologies. In the second part of the thesis, steady-state models of some of the advanced fossil fuel power generation technologies are presented. The impacts of various parameters on the solid oxide fuel cell (SOFC) overpotentials and outputs are investigated. The detail analyses of operation of the hybrid SOFC-gas turbine (GT) cycle when fuelled with methane and syngas demonstrate that the efficiencies of the cycles with and without anode exhaust recirculation are close, but the specific power of the former is much higher. The parametric analysis of the performance of the hybrid SOFC-GT cycle indicates that increasing the system operating pressure and SOFC operating temperature and fuel utilization factor improves cycle efficiency, but the effects of the increasing SOFC current density and turbine inlet temperature are not favourable. The analysis of the operation of the system when fuelled with a wide range of fuel types demonstrates that the hybrid SOFC-GT cycle efficiency can be between 59% and 75%, depending on the inlet fuel type. Then, the system performance is investigated when methane as a reference fuel is replaced with various species that can be found in the fuel, i.e., H2, CO2, CO, and N 2. The results point out that influence of various species can be significant and different for each case. The experimental and numerical analyses of a biodiesel fuelled micro gas turbine indicate that fuel switching from petrodiesel to biodiesel can influence operational parameters of the system. The modeling results of gas turbine-based power plants signify that relatively simple models can predict plant performance with acceptable accuracy. The unique feature of these models is that they are developed based on similar assumptions and run at similar conditions; therefore, their results can be compared. This work demonstrates that, although utilization of fossil fuels for power generation is inevitable, at least in the short- and mid-term future, it is possible and practical to carry out such utilization more efficiently and in an environmentally friendlier manner.

Zabihian, Farshid

382

Genetic evidence of an early exit of Homo sapiens sapiens from Africa through eastern Africa  

Microsoft Academic Search

The out-of-Africa scenario has hitherto provided little evidence for the precise route by which modern humans left Africa. Two major routes of dispersal have been hypothesized: one through North Africa into the Levant, documented by fossil remains, and one through Ethiopia along South Asia, for which little, if any, evidence exists. Mitochondrial DNA (mtDNA) can be used to trace maternal

Lluís Quintana-Murci; Ornella Semino; Hans-J. Bandelt; Giuseppe Passarino; Ken McElreavey; A. Silvana Santachiara-Benerecetti

1999-01-01

383

Earth's early fossil record: Why not look for similar fossils on Mars?  

NASA Technical Reports Server (NTRS)

The oldest evidence of life on Earth is discussed with attention being given to the structure and formation of stromatolites and microfossils. Fossilization of microbes in calcium carbonate or chert media is discussed. In searching for fossil remains on Mars, some lessons learned from the study of Earth's earliest fossil record can be applied. Certain sedimentary rock types and sedimentary rock configurations should be targeted for investigation and returned by the Martian rover and ultimately by human explorers. Domical, columnar to wavy laminated stratiform sedimentary rocks that resemble stromatolites should be actively sought. Limestone, other carbonates, and chert are the favored lithology. Being macroscopic, stromatolites might be recognized by an intelligent unmanned rover. In addition, black, waxy chert with conchoidal fracture should be sought. Chert is by far the preferred lithology for the preservation of microbes and chemical fossils. Even under optimal geological conditions (little or no metamorphism or tectonic alteration, excellent outcrops, and good black chert) and using experienced field biogeologists, the chances of finding well preserved microbial remains in chert are very low.

Awramik, Stanley M.

1989-01-01

384

Species longevity in North American fossil mammals.  

PubMed

Species longevity in the fossil record is related to many paleoecological variables and is important to macroevolutionary studies, yet there are very few reliable data on average species durations in Cenozoic fossil mammals. Many of the online databases (such as the Paleobiology Database) use only genera of North American Cenozoic mammals and there are severe problems because key groups (e.g. camels, oreodonts, pronghorns and proboscideans) have no reliable updated taxonomy, with many invalid genera and species and/or many undescribed genera and species. Most of the published datasets yield species duration estimates of approximately 2.3-4.3 Myr for larger mammals, with small mammals tending to have shorter species durations. My own compilation of all the valid species durations in families with updated taxonomy (39 families, containing 431 genera and 998 species, averaging 2.3 species per genus) yields a mean duration of 3.21 Myr for larger mammals. This breaks down to 4.10-4.39 Myr for artiodactyls, 3.14-3.31 Myr for perissodactyls and 2.63-2.95 Myr for carnivorous mammals (carnivorans plus creodonts). These averages are based on a much larger, more robust dataset than most previous estimates, so they should be more reliable for any studies that need species longevity to be accurately estimated. PMID:25236413

Prothero, Donald R

2014-08-01

385

Tiny Fossil Sheds Light on Mammalian Evolution  

NSDL National Science Digital Library

In the most recent issue of Science, a team of American and Chinese scientists announced the discovery of the fossil of a tiny shrew-like creature that lived 195 million years ago, 45 million years before previously discovered mammals. Found in 1985 in Yunnan province, China, the fossil was originally believed to be merely a bone fragment because of its small size. It has now been named Hadrocodium wui, ("Fullhead"), and could possibly be the direct ancestor of all living mammals. Hadrocodium was an insectivore, eating worms and small insects. Though it weighed only two grams (the weight of a paper clip), Hadrocodium had a considerably larger brain than most known mammals from the early Jurassic period. The tiny skull also possesses three other key traits that are characteristic of the transition from mammal-like animals to true mammals: a three-bone middle ear separated from the jaw, matching upper and lower teeth, and a powerful jaw hinge. Readers can begin learning more about this discovery with the Science article. Additional coverage is provided by Discovery news, the BBC, National Geographic, ABC News, and CNN.

de Nie, Michael Willem.

2001-01-01

386

Fossil energy biotechnology: A research needs assessment. Final report  

SciTech Connect

The Office of Program Analysis of the US Department of Energy commissioned this study to evaluate and prioritize research needs in fossil energy biotechnology. The objectives were to identify research initiatives in biotechnology that offer timely and strategic options for the more efficient and effective uses of the Nation`s fossil resource base, particularly the early identification of new and novel applications of biotechnology for the use or conversion of domestic fossil fuels. Fossil energy biotechnology consists of a number of diverse and distinct technologies, all related by the common denominator -- biocatalysis. The expert panel organized 14 technical subjects into three interrelated biotechnology programs: (1) upgrading the fuel value of fossil fuels; (2) bioconversion of fossil feedstocks and refined products to added value chemicals; and, (3) the development of environmental management strategies to minimize and mitigate the release of toxic and hazardous petrochemical wastes.

Not Available

1993-11-01

387

The Macroeconomic Transition to a Fossil-Fuel-Free Economy  

Microsoft Academic Search

In this paper I discuss causes and consequences of transition toward a fossil-fuel-free economy. In the long run, fossil fuel's finiteness will cause a rise in their prices and are expected to lead economies to the employment of renewable-energy sources, as an alternative to the fossil fuel currently at use. I therefore developed a general equilibrium model which makes possible

Sagi Dagan

388

We Can Use Fossils to Learn about Paleoecology  

NSDL National Science Digital Library

This site explains how to use evidence from fossils to understand the ecology of ancient organisms. Fossils provide clues and together abiotic and biotic factors combine to form complete ecosystems, each with its own unique ecology and history. Predator and prey relationships and dispersal are used as examples to show how fossils can also tell us about biotic factors, such as what organisms are present and how they interact. The site shows how fossils tell many stories about past ecology and that these stories may be about climate, changing environments, and interactions between organisms.

389

Calibrating the Tree of Life: fossils, molecules and evolutionary timescales  

PubMed Central

Background Molecular dating has gained ever-increasing interest since the molecular clock hypothesis was proposed in the 1960s. Molecular dating provides detailed temporal frameworks for divergence events in phylogenetic trees, allowing diverse evolutionary questions to be addressed. The key aspect of the molecular clock hypothesis, namely that differences in DNA or protein sequence between two species are proportional to the time elapsed since they diverged, was soon shown to be untenable. Other approaches were proposed to take into account rate heterogeneity among lineages, but the calibration process, by which relative times are transformed into absolute ages, has received little attention until recently. New methods have now been proposed to resolve potential sources of error associated with the calibration of phylogenetic trees, particularly those involving use of the fossil record. Scope and Conclusions The use of the fossil record as a source of independent information in the calibration process is the main focus of this paper; other sources of calibration information are also discussed. Particularly error-prone aspects of fossil calibration are identified, such as fossil dating, the phylogenetic placement of the fossil and the incompleteness of the fossil record. Methods proposed to tackle one or more of these potential error sources are discussed (e.g. fossil cross-validation, prior distribution of calibration points and confidence intervals on the fossil record). In conclusion, the fossil record remains the most reliable source of information for the calibration of phylogenetic trees, although associated assumptions and potential bias must be taken into account. PMID:19666901

Forest, Félix

2009-01-01

390

Looking for Fossil Bacteria in Martian Materials  

NASA Technical Reports Server (NTRS)

The rationale for looking for prokaryote fossils in Martian materials is based on our present understanding of the environmental evolution of that planet in comparison to the history of the terrestrial environments and the development and evolution of life on Earth. On Earth we have clear, albeit indirect, evidence of life in 3.8 b.y.-old rocks from Greenland and the first morphological fossils in 3.3-3.5 b.y.-old cherts from South Africa and Australia. In comparison, Mars, being smaller, probably cooled down after initial aggregation faster than the Earth. Consequently, there could have been liquid water on its surface earlier than on Earth. With a similar exogenous and endogenous input of organics and life-sustaining nutrients as is proposed for the Earth, life could have arisen on that planet, possibly slightly earlier dm it did on Earth. Whereas on Earth liquid water has remained at the surface of the planet since about 4.4 b.y. (with some possible interregnums caused by planet-sterilising impacts before 3.8. b.y. and perhaps a number of periods of a totally frozen Earth, this was not the case with Mars. Although it is not known exactly when surficial water disappeared from the surface, there would have been sufficient time for life to have developed into something similar to the terrestrial prokaryote stage. However, given the earlier environmental deterioration, it is unlikely that it evolved into the eukaryote stage and even evolution of oxygenic photosynthesis may not have been reached. Thus, the impetus of research is on single celled life simnilar to prokaryotes. We are investigating a number of methods of trace element analysis with respect to the Early Archaean microbial fossils. Preliminary neutron activation analysis of carbonaceous layers in the Early Archaean cherts from South Africa and Australia shows some partitioning of elements such as As, Sb, Cr with an especial enrichment of lanthanides in a carbonaceous-rich banded iron sediment . More significantly, preliminary TOF-SIMS investigations of organics in the cherts reveals the presence of a biomarker, which appears to be a derivative of bacterial polymer, in the carbonaceous parts of the rocks. We conclude that a combination of morphological, isotope and biogeochemical methods can be used to successfully identify signs of life in terrestrial material, and that these methods will be useful in searching for signs of life in extraterrestrial materials.

Westall, F.; Walsh, M. M.; Mckay, D. D.; Wentworth, S.; Gibson, E. K.; Steele, A.; Toporski, J.; Lindstrom, D.; Martinez, R.; Allen, C. C.

1999-01-01

391

Homo-oligomerization of human corneodesmosin is mediated by its N-terminal glycine loop domain.  

PubMed

Corneodesmosin (CDSN), a glycoprotein expressed during the late stages of epidermal differentiation, localizes in the extracellular core of upper desmosomes and of corneodesmosomes. Since it displays homophilic adhesive properties, CDSN is thought to reinforce cell-cell cohesion within the upper layers of the epidermis. CDSN presents two serine- and glycine-rich domains in its N- and C-terminus that may fold into highly flexible and adhesive secondary structures called glycine loops. We analyzed the importance of these domains in CDSN homophilic adhesion by producing full-length and truncated recombinant forms of the protein deleted of the N- and/or the C-terminal domain. The adhesive properties of the various proteins were then tested in vitro by overlay binding assays and surface plasmon resonance quantitative analysis. Experiments evidenced the homophilic adhesive properties of the N-terminal glycine loop domain, confirming its involvement in CDSN-CDSN interactions. They further indicated that most of the C-terminal domain is not necessary for the adhesive properties of the protein. The dissociation constant (K(D)) was calculated to be 1.3x10(-5) M. This interaction strength might allow dynamic regulation of the CDSN-CDSN association to occur in vivo. Moreover, molecular filtration analyses demonstrated for the first time that non-glycosylated CDSN is able to spontaneously form large homo-oligomers in vitro and that the N-terminal glycine loop domain is necessary for the formation of these macromolecular complexes. PMID:15086562

Caubet, Cécile; Jonca, Nathalie; Lopez, Frédéric; Estève, Jean-Pierre; Simon, Michel; Serre, Guy

2004-03-01

392

Homo-?-amino acid containing MBP(85-99) analogs alleviate experimental autoimmune encephalomyelitis.  

PubMed

MBP(85-99), an immuno-dominant epitope of myelin basic protein which binds to the major histocompatibility complex haplotype HLA-DR2 is widely implicated in the pathogenesis of multiple sclerosis. J5, an antagonist of MBP(85-99), that blocks the binding of MBP(85-99) to soluble HLA-DR2b much more efficiently than glatiramer acetate (a random copolymer comprising major MHC and T-cell receptor contact residues), was transformed into analogs with superior biological half-lives and antagonistic-activities by substitution of some of its residues with homo-?-amino acids. S18, the best analog obtained ameliorated symptoms of experimental autoimmune encephalomyelitis at least twice more effectively than glatiramer acetate or J5. S18 displayed marked resistance to proteolysis in-vitro; biological impact of which was evident in the form of delayed clinical onset of disease and prolonged therapeutic-benefits. Besides active suppression of MBP(85-99)-reactive CD4(+) T-cells in-vitro and in-vivo S18 treatment also generated IL-4 producing CD4(+) T-cell clones, through which protective effect could be transferred passively. PMID:25644378

Kant, Ravi; Pasi, Shweta; Surolia, Avadhesha

2015-01-01

393

DFT studies on vibrational spectra, HOMO-LUMO, NBO and thermodynamic function analysis of cyanuric fluoride  

NASA Astrophysics Data System (ADS)

In this work, the theoretical vibrational spectral characteristics of cyanuric fluoride (C3N3F3) have been investigated and compared with existing experimental results. The density functional theoretical (DFT) computations were performed at the B3LYP level with the basis sets 6-31G(d,p) and 6-311++G(d,p) levels to derive the optimized geometry, vibrational wavenumbers with IR intensities of cyanuric fluoride. In addition, the molecular orbital calculations such as Natural Bond Orbitals (NBOs), HOMO-LUMO energy gap and Mapped molecular Electrostatic Potential (MEP) surfaces were also performed with the same level of DFT. Electronic stability of the compound arising from hyper conjugative interactions and charge delocalization were also investigated based on the natural bond orbital (NBO) analysis. Effective stabilization energy E(2) connected with the interactions of the ? and the lone pair of electrons was determined by the NBO analysis. Mulliken population analysis on atomic charges is also calculated. The thermodynamic properties of the cyanuric fluoride at different temperatures have also been calculated for the range of temperature 50-1000 K.

Prabhaharan, M.; Prabakaran, A. R.; Gunasekaran, S.; Srinivasan, S.

2015-02-01

394

Viabilities of D. subobscura homo- and heterokaryotypes at optimal and stress temperatures. II. Seasonal component analysis.  

PubMed

Here we report the viability of natural chromosomal O-inversion structural homo- and heterokaryotypes in a population of D. subobscura from Avala Mountain, Serbia, subjected to cold and heat stress during spring 2004. These results were compared with those observed in the same population in September 2004. We detected protection of a great number of lethal genes in O-chromosome lethal heterozygous combinations, independently of inversion backgrounds and temperature stress. The positive epistatic interactions of mildly-deleterious genes observed only in O-inversion heterokaryotypes (at distinct temperatures) and lethal genes in O-inversion homokaryotypes (under temperature stress only) could be responsible for reducing the genetic load. The seasonal fluctuations in frequencies of several chromosomal arrangements and karyotypes indicate a seasonal adaptation to changeable environmental conditions. The sample of D. subobscura collected in spring 2004 was tolerant to cold but not to heat, and these results point to tolerance to extreme low temperatures, possibly as a result of natural selection. Also, a non-random distribution of distinct combinations of viability classes among several O-inversion karyotypes (under both optimal conditions and heat stress) was observed. This observation could be taken as evidence of co-adaptation: different capacities of several O-inversion karyotypes with different combinations of genes to tolerate a range of temperatures. We conclude that frequency-dependent and supergene selection are balancing selection mechanisms and are responsible for the protection of chromosomal inversions in natural populations of D. subobscura. PMID:20536546

Zivanovic, Goran; Mestres, Francesc

2010-04-01

395

Two conformational states in the crystal structure of the Homo sapiens cytoplasmic ribosomal decoding A site  

PubMed Central

The decoding A site of the small ribosomal subunit is an RNA molecular switch, which monitors codon–anticodon interactions to guarantee translation fidelity. We have solved the crystal structure of an RNA fragment containing two Homo sapiens cytoplasmic A sites. Each of the two A sites presents a different conformational state. In one state, adenines A1492 and A1493 are fully bulged-out with C1409 forming a wobble-like pair to A1491. In the second state, adenines A1492 and A1493 form non-Watson–Crick pairs with C1409 and G1408, respectively while A1491 bulges out. The first state of the eukaryotic A site is, thus, basically the same as in the bacterial A site with bulging A1492 and A1493. It is the state used for recognition of the codon/anticodon complex. On the contrary, the second state of the H.sapiens cytoplasmic A site is drastically different from any of those observed for the bacterial A site without bulging A1492 and A1493. PMID:16452297

Kondo, Jiro; Urzhumtsev, Alexandre; Westhof, Eric

2006-01-01

396

Low-energy (5-25 eV) electron damage to homo-oligonucleotides.  

PubMed

Radiation-induced damage to homo-oligonucleotides is investigated by electron-stimulated desorption of neutral fragments from chemisorbed organic films. Six and 12 mers of cytidine phosphate (poly dCs) and thymidine phosphate (poly dTs) are chemisorbed from various solutions onto a crystalline gold substrate by a thiol modification at the 3' end and are irradiated under ultra-high vacuum conditions with 5-25 eV electrons. The mass selected neutral desorption yields consist mainly of fragments of the DNA bases, i.e. CN and OCN (and/or H2NCN for poly dCs) from both poly dCs and poly dTs, indicating that the electrons interact specifically via fragmentation of the aromatic ring of either of the bases. Other heavier fragments are also detected such as H3CC-CO from poly dTs. The yields generally possess a threshold near 5 eV and a broad maximum around 12-13 eV incident electron energy. Dissociative electron attachment as well as electronically excited neutral or cation states are believed to be responsible for the various desorption yields. The latter yields are consistently larger for oligos chemisorbed from water and acetone solutions, compared to methanol solution. The invariance of the fragment yield intensities with oligo length suggests that the molecules are likely to adsorb almost parallel to the surface. PMID:10073671

Dugal, P C; Huels, M A; Sanche, L

1999-03-01

397

Calix[n]imidazolium as a new class of positively charged homo-calix compounds  

PubMed Central

Macrocycles based on neutral calixarenes and calixpyrroles have been extensively explored for ion binding, molecular assembly and related applications. Given that only these two types of calix compounds and their analogs are available, the introduction of new forms of widely usable calix macrocycles is an outstanding challenge. Here we report the quadruply/quintuply charged imidazole-based homo-calix compounds, calix[4/5]imidazolium. The noncovalent (C-H)+/?+-anion interactions of the imidazolium rings with anions inside and outside the cone are the stabilizing factors for crystal packing, resulting in self-assembled arrays of cone-shaped calix-imidazolium molecules. Calix[4]imidazolium senses fluoride selectively even in aqueous solutions. Calix[5]imidazolium recognizes neutral fullerenes through ?+–? interactions and makes them soluble in water, which could be useful in fullerene chemistry. Not only derivatization and ring expansion of calix[n]imidazolium, but also their utilization in ionic liquids, carbene chemistry and nanographite/graphene exfoliation could be exploited. PMID:23653209

Chun, Young; Jiten Singh, N; Hwang, In-Chul; Woo Lee, Jung; Yu, Seong Uk; Kim, Kwang S

2013-01-01

398

Molecular structure, vibrational spectroscopy, NBO and HOMO, LUMO studies of o-methoxybenzonitrile  

NASA Astrophysics Data System (ADS)

In the present study, the FT-IR and FT-Raman spectra of o-methoxybenzonitrile (O-MBN) have been recorded in the region 4000-400 cm-1 and 3500-50 cm-1, respectively. The fundamental modes of vibrational frequencies of O-MBN are assigned. Theoretical information on the optimized geometry, harmonic vibrational frequencies, infrared and Raman intensities were obtained by means of ab initio Hartree-Fock (HF) and density functional theory (DFT) gradient calculations with complete relaxation in the potential energy surface using 6-311++G(d,p) basis set. The vibrational frequencies which were determined experimentally from the spectral data are compared with those obtained theoretically from ab initio and DFT calculations. A close agreement was achieved between the observed and calculated frequencies by refinement of the scale factors. The infrared and Raman spectra were also predicted from the calculated intensities. Thermodynamic properties like entropy, heat capacity, zero point energy, have been calculated for the molecule. The predicted first hyperpolarizability also shows that the molecule might have a reasonably good non-linear optical (NLO) behavior. The calculated HOMO-LUMO energy gap reveals that charge transfer occurs within the molecule. Stability of the molecule arising from hyper conjugative interactions, charge delocalization have been analyzed using natural bond orbitals (NBO) analysis. Unambiguous vibrational assignment of all the fundamentals was made using the total energy distribution (TED).

Elanthiraiyan, M.; Jayasudha, B.; Arivazhagan, M.

2015-01-01

399

Analysis of the “thermodynamic information content” of a Homo sapiens structural database reveals hierarchical thermodynamic organization  

PubMed Central

Classification of the amounts and types of lower order structural elements in proteins is a prerequisite to effective comparisons between protein folds. In an effort to provide an additional vehicle for fold comparison, we present an alternative classification scheme whereby protein folds are represented in statistical thermodynamic terms in such a way as to illuminate the energetic building blocks within protein structures. The thermodynamic relationship is examined between amino acid sequences and the conformational ensembles for a database of 159 Homo sapiens protein structures ranging from 50 to 250 amino acids. Using hierarchical clustering, it is shown through fold-recognition experiments that (1) eight thermodynamic environmental descriptors sufficiently accounts for the energetic variation within the native state ensembles of the H. sapiens structural database, (2) an amino acid library of only six residue types is sufficient to encode >90% of the thermodynamic information required for fold specificity in the entire database, and (3) structural resolution of the statistically derived environments reveals sequential cooperative segments throughout the protein, which are independent of secondary structure. As the first level of thermodynamic organization in proteins, these segments represent the thermodynamic counterpart to secondary structure. PMID:15215522

Larson, Scott A.; Hilser, Vincent J.

2004-01-01

400

Temporal Coherence for Pure Tones in Budgerigars (Melopsittacus undulatus) and Humans (Homo sapiens).  

PubMed

Auditory scene analysis has been suggested as a universal process that exists across all animals. Relative to humans, however, little work has been devoted to how animals perceptually isolate different sound sources. Frequency separation of sounds is arguably the most common parameter studied in auditory streaming, but it is not the only factor contributing to how the auditory scene is perceived. Researchers have found that in humans, even at large frequency separations, synchronous tones are heard as a single auditory stream, whereas asynchronous tones with the same frequency separations are perceived as 2 distinct sounds. These findings demonstrate how both the timing and frequency separation of sounds are important for auditory scene analysis. It is unclear how animals, such as budgerigars (Melopsittacus undulatus), perceive synchronous and asynchronous sounds. In this study, budgerigars and humans (Homo sapiens) were tested on their perception of synchronous, asynchronous, and partially overlapping pure tones using the same psychophysical procedures. Species differences were found between budgerigars and humans in how partially overlapping sounds were perceived, with budgerigars more likely to segregate overlapping sounds and humans more apt to fuse the 2 sounds together. The results also illustrated that temporal cues are particularly important for stream segregation of overlapping sounds. Lastly, budgerigars were found to segregate partially overlapping sounds in a manner predicted by computational models of streaming, whereas humans were not. (PsycINFO Database Record (c) 2014 APA, all rights reserved). PMID:25419717

Neilans, Erikson G; Dent, Micheal L

2014-11-24

401

Indium oxide thin-film homo-junctions: Morphology and electrical properties  

NASA Astrophysics Data System (ADS)

Indium oxide shows an unusual combination of electrical and optical properties that give rise to a broad range of applications in optoelectronic devices. Here, we report results of structural, x-ray photoelectron spectroscopy, and electrical transport studies of transparent homo-junctions, obtained by sequential growth of polycrystalline thin layers of indium oxide under O2-rich and O2-poor conditions. We find that the growth temperature, which affects significantly film morphology, is critical for the rectifying behavior of the junctions. Only junctions grown at about 350 °C are rectifying. We also find that p-type-like layers have higher concentration of inter-grain oxygen than n-type layers, presumably coming from oxygen-rich deposition conditions and from much larger number of grain boundaries than in n-type layers. We conjecture that the segregation of oxygen ions at grain boundaries is responsible for the formation of inversion layers in O2-rich films and their apparent p-type dc conduction. This mechanism significantly modifies the capacitance-voltage characteristics of the junctions. However, the rectifying mechanism can be accounted for by a space-charge layer at the p-n interface. Such behavior might be important in other polycrystalline thin films with a large number of interface defects at grain boundaries.

Stankiewicz, Jolanta; Villuendas, Francisco; Pilar Lozano, María; Díez, Isabel

2013-08-01

402

Vibrational, UV spectra, NBO, first order hyperpolarizability and HOMO-LUMO analysis of carvedilol  

NASA Astrophysics Data System (ADS)

In this work, we have investigated experimentally and theoretically on the molecular structure, vibrational spectra, UV spectral analysis and NBO studies of cardio-protective drug carvedilol. The FT-Raman and FT-IR spectra for carvedilol in the solid phase have been recorded in the region 4000-100 cm-1 and 4000-400 cm-1 respectively. Theoretical calculations were performed by using density functional theory (DFT) method at B3LYP/6-31G(d,p) and B3LYP/6-31++G(d,p) basis set levels. The harmonic vibrational frequencies, the optimized geometric parameters have been interpreted and compared with the reported experimental values. The complete vibrational assignments were performed on the basis of potential energy distribution (PED) of the vibrational modes. The thermodynamic properties and molecular electrostatic potential surfaces of the molecule were constructed. The electronic absorption spectrum was recorded in the region 400-200 nm and electronic properties such as HOMO and LUMO energies were calculated. The stability of the molecule arising from hyper conjugative interactions and charge delocalization have been analyzed from natural bond orbital (NBO) analysis. The first order hyperpolarizability of the title molecule was also calculated. The photo stability of carvedilol under different storage conditions were analyzed using UV-Vis spectral technique.

Swarnalatha, N.; Gunasekaran, S.; Nagarajan, M.; Srinivasan, S.; Sankari, G.; Ramkumaar, G. R.

2015-02-01

403

Allostery at G Protein-Coupled Receptor Homo- and Heteromers: Uncharted Pharmacological Landscapes  

PubMed Central

For many years seven transmembrane domain G protein-coupled receptors (GPCRs) were thought to exist and function exclusively as monomeric units. However, evidence both from native cells and heterologous expression systems has demonstrated that GPCRs can both traffic and signal within higher-order complexes. As for other protein-protein interactions, conformational changes in one polypeptide, including those resulting from binding of pharmacological ligands, have the capacity to alter the conformation and therefore the response of the interacting protein(s), a process known as allosterism. For GPCRs, allosterism across homo- or heteromers, whether dimers or higher-order oligomers, represents an additional topographical landscape that must now be considered pharmacologically. Such effects may offer the opportunity for novel therapeutic approaches. Allosterism at GPCR heteromers is particularly exciting in that it offers additional scope to provide receptor subtype selectivity and tissue specificity as well as fine-tuning of receptor signal strength. Herein, we introduce the concept of allosterism at both GPCR homomers and heteromers and discuss the various questions that must be addressed before significant advances can be made in drug discovery at these GPCR complexes. PMID:21079041

Smith, Nicola J.

2010-01-01

404

Blood, bulbs, and bunodonts: on evolutionary ecology and the diets of Ardipithecus, Australopithecus, and early Homo.  

PubMed

Beginning with Darwin, some have argued that predation on other vertebrates dates to the earliest stages of hominid evolution, and can explain many uniquely human anatomical and behavioral characters. Other recent workers have focused instead on scavenging, or particular plant foods. Foraging theory suggests that inclusion of any food is influenced by its profitability and distribution within the consumer's habitat. The morphology and likely cognitive abilities of Ardipithecus, Australopithecus, and early Homo suggest that while hunting and scavenging occurred, their profitability generally would have been considerably lower than in extant primates and/or modern human hunter-gatherers. On the other hand, early hominid diet modelers should not focus solely on plant foods, as this overlooks standard functional interpretations of the early hominid dentition, their remarkable demographic success, and the wide range of available food types within their likely day ranges. Any dietary model focusing too narrowly on any one food type or foraging strategy must be viewed with caution. We argue that early hominid diet can best be elucidated by consideration of their entire habitat-specific resource base, and by quantifying the potential profitability and abundance of likely available foods. PMID:25510078

Sayers, Ken; Lovejoy, C Owen

2014-12-01

405

Homo- and heterofermentative lactobacilli differently affect sugarcane-based fuel ethanol fermentation.  

PubMed

Bacterial contamination during industrial yeast fermentation has serious economic consequences for fuel ethanol producers. In addition to deviating carbon away from ethanol formation, bacterial cells and their metabolites often have a detrimental effect on yeast fermentative performance. The bacterial contaminants are commonly lactic acid bacteria (LAB), comprising both homo- and heterofermentative strains. We have studied the effects of these two different types of bacteria upon yeast fermentative performance, particularly in connection with sugarcane-based fuel ethanol fermentation process. Homofermentative Lactobacillus plantarum was found to be more detrimental to an industrial yeast strain (Saccharomyces cerevisiae CAT-1), when compared with heterofermentative Lactobacillus fermentum, in terms of reduced yeast viability and ethanol formation, presumably due to the higher titres of lactic acid in the growth medium. These effects were only noticed when bacteria and yeast were inoculated in equal cell numbers. However, when simulating industrial fuel ethanol conditions, as conducted in Brazil where high yeast cell densities and short fermentation time prevail, the heterofermentative strain was more deleterious than the homofermentative type, causing lower ethanol yield and out competing yeast cells during cell recycle. Yeast overproduction of glycerol was noticed only in the presence of the heterofermentative bacterium. Since the heterofermentative bacterium was shown to be more deleterious to yeast cells than the homofermentative strain, we believe our findings could stimulate the search for more strain-specific antimicrobial agents to treat bacterial contaminations during industrial ethanol fermentation. PMID:24198118

Basso, Thiago Olitta; Gomes, Fernanda Sgarbosa; Lopes, Mario Lucio; de Amorim, Henrique Vianna; Eggleston, Gillian; Basso, Luiz Carlos

2014-01-01

406

DFT studies on vibrational spectra, HOMO-LUMO, NBO and thermodynamic function analysis of cyanuric fluoride.  

PubMed

In this work, the theoretical vibrational spectral characteristics of cyanuric fluoride (C3N3F3) have been investigated and compared with existing experimental results. The density functional theoretical (DFT) computations were performed at the B3LYP level with the basis sets 6-31G(d,p) and 6-311++G(d,p) levels to derive the optimized geometry, vibrational wavenumbers with IR intensities of cyanuric fluoride. In addition, the molecular orbital calculations such as Natural Bond Orbitals (NBOs), HOMO-LUMO energy gap and Mapped molecular Electrostatic Potential (MEP) surfaces were also performed with the same level of DFT. Electronic stability of the compound arising from hyper conjugative interactions and charge delocalization were also investigated based on the natural bond orbital (NBO) analysis. Effective stabilization energy E((2)) connected with the interactions of the ? and the lone pair of electrons was determined by the NBO analysis. Mulliken population analysis on atomic charges is also calculated. The thermodynamic properties of the cyanuric fluoride at different temperatures have also been calculated for the range of temperature 50-1000K. PMID:25448950

Prabhaharan, M; Prabakaran, A R; Gunasekaran, S; Srinivasan, S

2015-02-01

407

Cold Spring Harbor symposia on quantitative biology: Volume 51, Molecular biology of Homo sapiens  

SciTech Connect

Thirteen years marked the time between the discovery of the double helix in 1953 and the elucidation of the genetic code in 1966. A similar interval has now passed since the development by Cohen and Boyer of a simple procedure for the cloning of selective DNA fragments. The scientific advances made possible by the subsequent modification and elaboration of these original cloning procedures now amaze, stimulate, and increasingly often overwhelm us. Facts that until recently were virtually unobtainable now flow forth almost effortlessly. Most excitingly, the frenetic pace of these new discoveries, instead of marking the impending end of a glorious moment of learning, give every indication of opening up scientific frontiers that will take hundreds if not thousands of years to explore thoroughly. This new era of enlightenment is nowhere more apparent than in our newfound ability to study ourselves at the molecular level. This volume is the first of two collections of papers submitted by the contributors to the Cold Spring Harbor symposia on quantitative biology for 1986 - molecular biology of Homo sapiens. Contained in this collection are 80 papers grouped into sessions entitled Human Gene Map, Genetic Diagnosis, Human Evolution, and Drugs Made Off Human Genes.

Not Available

1986-01-01

408

Homo-?-amino acid containing MBP(85–99) analogs alleviate experimental autoimmune encephalomyelitis  

PubMed Central

MBP(85–99), an immuno-dominant epitope of myelin basic protein which binds to the major histocompatibility complex haplotype HLA-DR2 is widely implicated in the pathogenesis of multiple sclerosis. J5, an antagonist of MBP(85–99), that blocks the binding of MBP(85–99) to soluble HLA-DR2b much more efficiently than glatiramer acetate (a random copolymer comprising major MHC and T-cell receptor contact residues), was transformed into analogs with superior biological half-lives and antagonistic-activities by substitution of some of its residues with homo-?-amino acids. S18, the best analog obtained ameliorated symptoms of experimental autoimmune encephalomyelitis at least twice more effectively than glatiramer acetate or J5. S18 displayed marked resistance to proteolysis in-vitro; biological impact of which was evident in the form of delayed clinical onset of disease and prolonged therapeutic-benefits. Besides active suppression of MBP(85–99)-reactive CD4+ T-cells in-vitro and in-vivo S18 treatment also generated IL-4 producing CD4+ T-cell clones, through which protective effect could be transferred passively. PMID:25644378

Kant, Ravi; Pasi, Shweta; Surolia, Avadhesha

2015-01-01

409

Gracility of the modern Homo sapiens skeleton is the result of decreased biomechanical loading.  

PubMed

The postcranial skeleton of modern Homo sapiens is relatively gracile compared with other hominoids and earlier hominins. This gracility predisposes contemporary humans to osteoporosis and increased fracture risk. Explanations for this gracility include reduced levels of physical activity, the dissipation of load through enlarged joint surfaces, and selection for systemic physiological characteristics that differentiate modern humans from other primates. This study considered the skeletal remains of four behaviorally diverse recent human populations and a large sample of extant primates to assess variation in trabecular bone structure in the human hip joint. Proximal femur trabecular bone structure was quantified from microCT data for 229 individuals from 31 extant primate taxa and 59 individuals from four distinct archaeological human populations representing sedentary agriculturalists and mobile foragers. Analyses of mass-corrected trabecular bone variables reveal that the forager populations had significantly higher bone volume fraction, thicker trabeculae, and consequently lower relative bone surface area compared with the two agriculturalist groups. There were no significant differences between the agriculturalist and forager populations for trabecular spacing, number, or degree of anisotropy. These results reveal a correspondence between human behavior and bone structure in the proximal femur, indicating that more highly mobile human populations have trabecular bone structure similar to what would be expected for wild nonhuman primates of the same body mass. These results strongly emphasize the importance of physical activity and exercise for bone health and the attenuation of age-related bone loss. PMID:25535352

Ryan, Timothy M; Shaw, Colin N

2015-01-13

410

Morphology of the nasal capsule of primates--with special reference to Daubentonia and Homo.  

PubMed

Primitive mammals are considered macrosmatic. They have very large and complicated nasal capsules, nasal cavities with extensive olfactory epithelia, and relatively large olfactory bulbs. The complicated structures of the nasal capsule follow a relatively conservative "bauplan," which is normally easy to see in earlier fetal stages; especially in altricial taxa it differentiates well into postnatal life. As anteriormost part of the chondrocranium, the nasal capsule is at first cartilaginous. Most of it ossifies endochondrally, but "appositional bone" ("Zuwachsknochen") is also common. Many fetal structures become resorbed. Together, all surviving bone structures form the ethmoid bone, but cartilages of the external nose and of the vomeronasal complex can persist throughout life. We describe in detail the anatomy of Daubentonia madagascariensis based on a fetal stage (41 mm HL) and an adult skull was analyzed by µCT. We found that the nasal capsule of this species is by far the most complicated one of all extant Primates. We also describe older fetuses of Homo sapiens (35 and 63 mm HL) as representative of a derived primate. The most significant feature of man--and probably of all anthropoids--is the complete loss of the recessus frontoturbinalis and its associated structures. It can be demonstrated that the evolutionary reductions within the primate nasal capsule mainly affect those structures associated with olfaction, whereas cartilages that are important for the biomechanics of the facial skull of the fetus persist. PMID:25312360

Maier, Wolfgang; Ruf, Irina

2014-11-01

411

Simulation of Threading Dislocation Images in X-ray Topographs of Silicon Carbide Homo-Epilayers  

SciTech Connect

Three types of dislocation are seen in homo-epilayers of SiC grown on 4H-SiC wafers with an 8 degree surface offcut: axial screw dislocations, basal plane dislocations propagated into the epilayer at an 8 degree inclination and threading edge dislocations. These types may be imaged by monochromatic synchrotron X-ray topography in the grazing-incidence reflection geometry using the 11{bar 2}8 reflection. Equations needed to apply the ray-tracing method of computer simulating X-ray topographic defect images in this experimental geometry were derived and used to simulate images of all three. Simulations for axial screw dislocations appear as white circles surrounded by narrow dark rings, and those for basal plane dislocations as linear white streaks, both consistent with experimental topographs. Simulations of the threading edge dislocations showed 4 {micro}m wide white ovals with narrow arcs of dark contrast at their ends, inclined relative to the g vector of the topograph according to the sign of their Burgers vector. These images resembled the experimental topographs inasmuch as was possible at the maximum resolution of X-ray topographs.

Vetter,W.; Tsuchida, H.; Kamata, I.; Dudley, M.

2005-01-01

412

Experimental and theoretical spectroscopic analysis, HOMO-LUMO, and NBO studies of cyanuric chloride.  

PubMed

The vibrational spectral analysis of cyanuric chloride was carried out by using FT-Raman and FT-IR spectra in the range 100-4000cm(-1) and 400-4000cm(-1) respectively. The structure optimization was done and structural characteristics were determined by Density Functional Theory (B3LYP) method with 6-31G(d,p) and 6-311++G(d,p) basis sets. The vibrational wavenumbers have been calculated and scaled values are compared with experimental FT-IR and FT-Raman spectra. A detailed interpretation of the vibrational spectra of the molecule has been made on the basis of the calculated Potential Energy Distribution (PED). The Natural bonding orbital (NBO) analysis performed to confirm the stability of the molecule arising from hyper conjugation and delocalization. The Mulliken atomic charges were also calculated. The computed HOMO-LUMO energy gap shows that charge transfer occurs within the molecule. The thermodynamic properties at different temperatures have been calculated from the vibrational analysis. PMID:24650880

Prabhaharan, M; Prabakaran, A R; Srinivasan, S; Gunasekaran, S

2014-06-01

413

Pathophysiology of GPCR Homo- and Heterodimerization: Special Emphasis on Somatostatin Receptors  

PubMed Central

G-protein coupled receptors (GPCRs) are cell surface proteins responsible for translating >80% of extracellular reception to intracellular signals. The extracellular information in the form of neurotransmitters, peptides, ions, odorants etc is converted to intracellular signals via a wide variety of effector molecules activating distinct downstream signaling pathways. All GPCRs share common structural features including an extracellular N-terminal, seven-transmembrane domains (TMs) linked by extracellular/intracellular loops and the C-terminal tail. Recent studies have shown that most GPCRs function as dimers (homo- and/or heterodimers) or even higher order of oligomers. Protein-protein interaction among GPCRs and other receptor proteins play a critical role in the modulation of receptor pharmacology and functions. Although ~50% of the current drugs available in the market target GPCRs, still many GPCRs remain unexplored as potential therapeutic targets, opening immense possibility to discover the role of GPCRs in pathophysiological conditions. This review explores the existing information and future possibilities of GPCRs as tools in clinical pharmacology and is specifically focused for the role of somatostatin receptors (SSTRs) in pathophysiology of diseases and as the potential candidate for drug discovery. PMID:24281555

Somvanshi, Rishi K.; Kumar, Ujendra

2012-01-01

414

Assessing trace element diffusion models in fossil and sub-fossil bone  

NASA Astrophysics Data System (ADS)

Three different diffusion models have been proposed to explain trace element uptake during fossilization of bone: diffusion-adsorption (DA), diffusion-recrystallization (DR), and double-medium diffusion (DMD). Theoretically, differences in trace element profiles, particularly the rare earth elements (REE) and U, can discriminate among these possibilities. In this study, we tested which model best explains natural samples by analyzing trace element profiles in natural bone using laser-ablation inductively-coupled plasma mass spectrometry (LA-ICP-MS). Fossil bones ranging in age from a few ka to over 100 Ma were analyzed along traverses from the outer cortical edge to the inner marrow cavity margin. Forty major, minor and trace elements were analyzed, notably Ca, P, transition metals, Sr, Ba, REE, U, Th and Pb. Spatial and analytical resolutions were ~10 ?m and ~100 ppb respectively. Many specimens show commonly observed exponential decreases in REE from the outer edge and marrow cavity, with relatively homogeneous U distributions. Yet, most significantly, specimens from American Falls (last interglacial) and Duck Point (last glacial maximum) show distinctive U plateaus adjacent to the outer and inner cortical bone margins. Whereas exponential profiles can be produced by different uptake processes, such plateaus are diagnostic of a DR mechanism. Our work is consistent with recent investigation of trace element diffusivities in modern fresh and deproteinated bone. These studies show similar diffusion rates for REE and U, so the profound disparity in U vs. REE profiles in most fossils cannot result solely from differences in volume diffusion within the context of DA and DMD. Rather, as a recrystallization front propagates into bone, the bone appears to encode changing soil water compositions with earlier vs. later compositions reflected in the bone margin vs. interior. Soil water U concentrations apparently remain nearly fixed during fossilization, whereas REE are rapidly stripped from the surrounding matrix, leading to nearly homogeneous U vs. steep REE profiles. However in our Pleistocene bones (American Falls and Duck Point), changes to U concentrations on the bone margin reveal more complex changes to boundary compositions, and eliminate both DA and DMD (alone) as the dominant mechanisms of trace element uptake. Our work reconciles disparate zoning patterns observed in fossil bone, and simplifies interpretations of soil or sediment water chemistry, but complicates U-series dating of fossils.

Suarez, C. A.; Kohn, M. J.

2012-12-01

415

Microbial biocatalyst developments to upgrade fossil fuels.  

PubMed

Steady increases in the average sulfur content of petroleum and stricter environmental regulations concerning the sulfur content have promoted studies of bioprocessing to upgrade fossil fuels. Bioprocesses can potentially provide a solution to the need for improved and expanded fuel upgrading worldwide, because bioprocesses for fuel upgrading do not require hydrogen and produce far less carbon dioxide than thermochemical processes. Recent advances have demonstrated that biodesulfurization is capable of removing sulfur from hydrotreated diesel to yield a product with an ultra-low sulfur concentration that meets current environmental regulations. However, the technology has not yet progressed beyond laboratory-scale testing, as more efficient biocatalysts are needed. Genetic studies to obtain improved biocatalysts for the selective removal of sulfur and nitrogen from petroleum provide the focus of current research efforts. PMID:16678400

Kilbane, John J

2006-06-01

416

What Can We Learn From Fossils  

NSDL National Science Digital Library

Students have learned throughout the course how paleontologists make interpretations about fossils. As we covered the various dinosaur groups we covered what interpretations have been made about their growth rates, eating habits, speeds, and etc. There is also a discussion of how paleontologists have made these interpretations. This activity is associated with the Taphonomy chapter and allows students to use the tools that they have acquired throughout the course to make interpretation about a modern animal and an extinct animal. Each student receives a packet of information on a modern animal and an extinct animal. This packet includes various pictures of the skeleton, foot prints, teeth, skull, and etc. To complete the assignment each student must synthesize the knowledge they learned throughout the course and make supported conclusions about each animal. They also must complete a write up of the locality of the extinct animal and what is known about the paleoecology.

Hochstein, Joann

417

Rates of speciation in the fossil record  

NASA Technical Reports Server (NTRS)

Data from palaeontology and biodiversity suggest that the global biota should produce an average of three new species per year. However, the fossil record shows large variation around this mean. Rates of origination have declined through the Phanerozoic. This appears to have been largely a function of sorting among higher taxa (especially classes), which exhibit characteristic rates of speciation (and extinction) that differ among them by nearly an order of magnitude. Secular decline of origination rates is hardly constant, however; many positive deviations reflect accelerated speciation during rebounds from mass extinctions. There has also been general decline in rates of speciation within major taxa through their histories, although rates have tended to remain higher among members in tropical regions. Finally, pulses of speciation appear sometimes to be associated with climate change, although moderate oscillations of climate do not necessarily promote speciation despite forcing changes in species' geographical ranges.

Sepkoski, J. J. Jr; Sepkoski JJ, J. r. (Principal Investigator)

1998-01-01

418

The future of oil: unconventional fossil fuels.  

PubMed

Unconventional fossil hydrocarbons fall into two categories: resource plays and conversion-sourced hydrocarbons. Resource plays involve the production of accumulations of solid, liquid or gaseous hydro-carbons that have been generated over geological time from organic matter in source rocks. The character of these hydrocarbons may have been modified subsequently, especially in the case of solids and extra-heavy liquids. These unconventional hydrocarbons therefore comprise accumulations of hydrocarbons that are trapped in an unconventional manner and/or whose economic exploitation requires complex and technically advanced production methods. This review focuses primarily on unconventional liquid hydro-carbons. The future potential of unconventional gas, especially shale gas, is also discussed, as it is revolutionizing the energy outlook in North America and elsewhere. PMID:24298078

Chew, Kenneth J

2014-01-13

419

FAST FOSSIL ROTATION OF NEUTRON STAR CORES  

SciTech Connect

It is argued that the superfluid core of a neutron star super-rotates relative to the crust, because stratification prevents the core from responding to the electromagnetic braking torque, until the relevant dissipative (viscous or Eddington-Sweet) timescale, which can exceed {approx}10{sup 3} yr and is much longer than the Ekman timescale, has elapsed. Hence, in some young pulsars, the rotation of the core today is a fossil record of its rotation at birth, provided that magnetic crust-core coupling is inhibited, e.g., by buoyancy, field-line topology, or the presence of uncondensed neutral components in the superfluid. Persistent core super-rotation alters our picture of neutron stars in several ways, allowing for magnetic field generation by ongoing dynamo action and enhanced gravitational wave emission from hydrodynamic instabilities.

Melatos, A., E-mail: amelatos@unimelb.edu.au [School of Physics, University of Melbourne, Parkville, VIC 3010 (Australia)

2012-12-10

420

Fossil Groups in the Local Universe  

NASA Technical Reports Server (NTRS)

The two galaxies observed as part of this project were originally selected as fossil group candidates because of their isolation from other galaxies and their apparent high X-ray luminosity and extended X-ray emission. However, the X-ray data available was minimal, being drawn from the ROSAT All-Sky Survey. We have performed an initial analysis of the XMM data from both galaxies and found that their gaseous halos are smaller, cooler, and less luminous than expected. In the case of NGC 57, the RASS estimate of extent and luminosity was biased because of a previously unidentified background group which is visible in the XMM data to one side of the galaxy. In the case of IC 153 1, the contribution from background point sources near the galaxy appears to be to blame. This suggests that both galaxies should be reclassified as isolated ellipticals. Such systems are very rare, and currently poorly understood; for comparison, there are now 6-10 known fossil groups, but only one isolated elliptical with useful X-ray data. We are currently re-analyzing the data for the two galaxies to take advantage of the calibration improvements of SAS 6.1, and to include calculations of the mass profiles of the two systems. A paper is currently in preparation dealing with the X-ray properties and environment of the galaxies, and we expect to submit this to the Astrophysical Journal within the next two months. Multi-band optical imaging of the field surrounding NGC 57 has been acquired to confirm its isolated status and provide more information on the background group. IC 1531 was accepted as a target in Chandra cycle 6 as part of a related proposal, and we intend to add this new observation to our XMM data when it becomes available. A second paper is planned to include the results of this combined analysis.

OSullivan, Ewan

2005-01-01

421

The eukaryotic fossil record in deep time  

NASA Astrophysics Data System (ADS)

Eukaryotic organisms are defining constituents of the Phanerozoic biosphere, but they also extend well back into the Proterozoic record, primarily in the form of microscopic body fossils. Criteria for identifying pre-Ediacaran eukaryotes include large cell size, morphologically complex cell walls and/or the recognition of diagnostically eukaryotic cell division patterns. The oldest unambiguous eukaryote currently on record is an acanthomorphic acritarch (Tappania) from the Palaeoproterozoic Semri Group of central India. Older candidate eukaryotes are difficult to distinguish from giant bacteria, prokaryotic colonies or diagenetic artefacts. In younger Meso- and Neoproterozoic strata, the challenge is to recognize particular grades and clades of eukaryotes, and to document their macro-evolutionary expression. Distinctive unicellular forms include mid-Neoproterozoic testate amoebae and phosphate biomineralizing 'scale-microfossils' comparable to an extant green alga. There is also a significant record of seaweeds, possible fungi and problematica from this interval, documenting multiple independent experiments in eukaryotic multicellularity. Taxonomically resolved forms include a bangiacean red alga and probable vaucheriacean chromalveolate algae from the late Mesoproterozoic, and populations of hydrodictyacean and siphonocladalean green algae of mid Neoproterozoic age. Despite this phylogenetic breadth, however, or arguments from molecular clocks, there is no convincing evidence for pre-Ediacaran metazoans or metaphytes. The conspicuously incomplete nature of the Proterozoic record makes it difficult to resolve larger-scale ecological and evolutionary patterns. Even so, both body fossils and biomarker data point to a pre-Ediacaran biosphere dominated overwhelming by prokaryotes. Contemporaneous eukaryotes appear to be limited to conspicuously shallow water environments, and exhibit fundamentally lower levels of morphological diversity and evolutionary turnover than their Phanerozoic counterparts. I will argue here that this fundamental change of state was driven by the early Ediacaran appearance of Eumetazoa, a uniquely complex clade of heterotrophic eukaryotes that redefined how the planet worked.

Butterfield, N.

2011-12-01

422

First report of (homo)anatoxin-a and dog neurotoxicosis after ingestion of benthic cyanobacteria in The Netherlands.  

PubMed

In April and May 2011, three dogs died and one dog became ill after swimming in Lake IJmeer (The Netherlands). At the time, the lake was infested with the benthic cyanobacterial species Phormidium. A Eurasian Coot (Fulica atra) and a Black-headed Gull (Chroicocephalus ridibundus) also died near Lake IJmeer in the same period. One of the dogs and both birds were subjected to a pathological investigation. Furthermore, the Phormidium mat; algal samples from the dikes; contents of the animals' digestive systems and organ tissues were analysed for the following cyanobacterial toxins: (homo)anatoxin-a; (7-deoxy-)cylindrospermopsin; saxitoxins and gonyautoxins by LC-MS/MS. Samples were also analysed for the nontoxic (homo)anatoxin-a metabolites dihydro(homo)anatoxin-a and epoxy(homo)anatoxin-a. The dog necropsy results indicated neurotoxicosis and its stomach contained Phormidium filaments. Anatoxin-a was detected in the Phormidium mat (272 ?g g?¹) dry weight, stdev 65, n=3) and in the dog's stomach contents (9.5 ?g g?¹ dry weight, stdev 2.4, n=3). Both samples also contained the anatoxin-a metabolite dihydroanatoxin-a, and a trace of homoanatoxin-a was detected in the Phormidium mat. The birds were in bad nutritive condition at the time of necropsy and their stomachs and intestines did not contain any cyanobacterial material. Furthermore, no cyanobacterial toxins were detected in their stomachs, intestines and organs and they both had lesions that are not associated with cyanobacterial intoxication. This is the first report of anatoxin-a and homoanatoxin-a occurrence in The Netherlands, these toxins have likely caused the deaths of three dogs. The birds probably died of other causes. Dutch recreational waters are at this moment only screened for pelagic cyanobacterial species, the current bathing water protocol therefore does not protect humans and animals from negative effects of blooms of benthic cyanobacteria. PMID:22534073

Faassen, Elisabeth J; Harkema, Liesbeth; Begeman, Lineke; Lurling, Miquel

2012-09-01

423

Ecology of Plio-Pleistocene Mammals in the Omo—Turkana Basin and the Emergence of Homo  

Microsoft Academic Search

Understanding the origin of the genus Homo in Africa remains one of the central problems in paleoanthropology. Consi derable empirical evidence relevant to this issue\\u000a derives from the Omo—Turkana Basin, which includes areas surrounding Lake Turkana in northern Kenya and the lower Omo River\\u000a Valley in southern Ethiopia (Fig. 15.1). This basin is well known for it rich record of

René Bobe; Meave G. Leakey

424

Fossil Leaves and Fossil Leaf n-Alkanes: Reconstructing the First Closed Canopied Rainforests  

NASA Astrophysics Data System (ADS)

Although the age and location is disputed, the rise of the first closed-canopy forest is likely linked with the expansion of angiosperms in the late Cretacous or early Cenozoic. The carbon isotope 'canopy effect' reflects the extent of canopy closure, and is well documented in ?13C values of the leaves and leaf lipids in modern forests. To test the extent of canopy closure among the oldest documented angiosperm tropical forests, we analyzed isotopic characteristics of leaf fossils and leaf waxes from the Guaduas and Cerrejón Formations. The Guaduas Fm. (Maastrichtian) contains some of the earliest angiosperm fossils in the Neotropics, and both leaf morphology and pollen records at this site suggest an open-canopy structure. The Cerrejón Fm. (Paleocene) contains what are believed to be the first recorded fossil leaves from a closed-canopy forest. We analyzed the bulk carbon isotope content (?13Cleaf) of 199 fossil leaves, as well as the n-alkane concentration and chain-length distribution, and ?13C of alkanes (?13Clipid) of 73 fossil leaves and adjacent sediment samples. Fossil leaves are dominated by eudicots and include ten modern plant families (Apocynaceae, Bombaceae, Euphorbaceae, Fabaceae, Lauraceae, Malvaceae, Meliaceae, Menispermaceae, Moraceae, Sapotaceae). We interpreted extent of canopy coverage based on the range of ?13Cleaf values. The narrow range of ?13C values in leaves from the Guaduas Fm (2.7‰) is consistent with an open canopy. A significantly wider range in values (6.3‰) suggests a closed-canopy signature for site 0315 of the Cerrejón Fm,. In contrast, at Site 0318, a lacustrine deposit, leaves had a narrow range (3.3‰) in ?13C values, and this is not consistent with a closed-canopy, but is consistent with leaf assemblages from a forest edge. Leaves that accumulate in lake sediments tend to be biased toward plants living at the lake edge, which do not experience closed-canopy conditions, and do not express the isotopic characteristics associated with canopy effect. A biomass flux-weighted model of alkane chain-length distribution and ?13Cleaf indicate n-alkanes extracted from bulk rock are consistent with inputs integrated over time from plants represented by fossil leaves. In a modern rainforest, we found leaf lipid amounts markedly higher in the shaded and moist understory, consistent with studies that show alkanes proffer fungal protection. Shade tolerance is associated with higher plant orders and, consistent with this, literature data for modern plants from 30 plant orders shows alkane production in asterids and rosids is 2 to 3 times greater than in basal angiosperms or gymnosperms. The lower clades tend to contain greater amounts of terpenoids and novel benzylisoquinoline alkaloids, rather than alkanes. For our three fossil floras, alkane abundance is strongly influenced by depositional setting, with preservation best in the lacustrine setting. Within each site, abundance patterns are potentially influenced by both taxonomic affiliation and by canopy structure as measured by ?13Cleaf values, and such relationships shed light on the combined influences of plant evolution, canopy structure and the function of biochemical resources on the geochemical record of the first rainforests.

Graham, H. V.; Freeman, K. H.

2013-12-01

425

Homo-oligomerization of the Activating Natural Killer Cell Receptor NKp30 Ectodomain Increases Its Binding Affinity for Cellular Ligands*  

PubMed Central

The natural cytotoxicity receptors, comprised of three type I membrane proteins NKp30, NKp44, and NKp46, are a unique set of activating proteins expressed mainly on the surface of natural killer (NK) cells. Among these, NKp30 is a major receptor targeting virus-infected cells, malignantly transformed cells, and immature dendritic cells. To date, only few cellular ligands of NKp30 have been discovered, and the molecular details of ligand recognition by NKp30 are poorly understood. Within the current study, we found that the ectodomain of NKp30 forms functional homo-oligomers that mediate high affinity binding to its corresponding cellular ligand B7-H6. Notably, this homo-oligomerization is strongly promoted by the stalk domain of NKp30. Based on these data, we suggest that homo-oligomerization of NKp30 in the plasma membrane of NK cells, which might be favored by IL-2-dependent up-regulation of NKp30 expression, provides a way to improve recognition and lysis of target cells by NK cells. PMID:24275655

Herrmann, Julia; Berberich, Hannah; Hartmann, Jessica; Beyer, Steffen; Davies, Karen; Koch, Joachim

2014-01-01

426

Solar decomposition of fossil fuels as an option for sustainability  

Microsoft Academic Search

This paper presents an overview on solar-thermal decomposition of fossil fuels as a viable option for transition path from today's permanent dependency on fossil fuels to tomorrow's solar fuels via solar thermochemical technology. The paper focuses on the thermochemical hydrogen generation technologies from concentrated solar energy and gives an assessment of the recent advancements in the hydrogen producing solar reactors.

Nesrin Ozalp; Abraham Kogan; Michael Epstein

2009-01-01

427

The dilemma of fossil fuel use and global climate change  

Microsoft Academic Search

The use of fossil fuels and relationship to climate change is discussed. As the use of fossil fuels has grown, the problems of protecting the environment and human health and safety have also grown, providing a continuing challenge to technological and managerial innovation. Today that challenge is to control atmospheric emissions from combustion, particularly those emissions that cause acidic deposition,

R. R. Judkins; W. Fulkerson; M. K. Sanghvi

1991-01-01

428

Transitional fossil earwigs - a missing link in Dermaptera evolution  

Microsoft Academic Search

BACKGROUND: The Dermaptera belongs to a group of winged insects of uncertain relationship within Polyneoptera, which has expanded anal region and adds numerous anal veins in the hind wing. Evolutional history and origin of Dermaptera have been in contention. RESULTS: In this paper, we report two new fossil earwigs in a new family of Bellodermatidae fam. nov. The fossils were

Jingxia Zhao; Yunyun Zhao; Chungkun Shih; Dong Ren; Yongjie Wang

2010-01-01

429

Mysterious Fossils from the Chesapeake Bay Impact Crater and Beyond  

USGS Multimedia Gallery

Photo of fossil algae (dinocyst). Specimen is about 90 micrometers across.The largest known impact crater in the U.S. lies buried beneath the Virginia Coastal Plain. The late Eocene Chesapeake Bay impact event caused a wide variety of distinctive features, such as fossil algae (dinocysts) that were ...

430

Fossil Ionized Bubbles Around Dead Quasars During Reionization  

E-print Network

One of the most dramatic signatures of the reionization era may be the enormous ionized bubbles around luminous quasars (with radii reaching ~40 comoving Mpc), which may survive as "fossil'' ionized regions long after their source shuts off. Here we study how the inhomogeneous intergalactic medium (IGM) evolves inside such fossils. The average recombination rate declines rapidly with time, and the brief quasar episode significantly increases the mean free path inside the fossil bubbles. As a result, even a weak ionizing background generated by galaxies inside the fossil can maintain it in a relatively highly and uniformly ionized state. For example, galaxies that would ionize 20-30% of hydrogen in a random patch of the IGM can maintain 80-90% ionization inside the fossil, for a duration much longer than the average recombination time in the IGM. Quasar fossils at zfossils, at z>10 have a weaker galaxy-generated ionizing background and a higher gas density, so they can attain a swiss-cheese topology similar to the rest of the IGM, but with a smaller contrast between the ionized bubbles and the partially neutral regions separating them. Analogous HeIII-fossils should exist around the epoch of HeII/HeIII reionization at z~3, although rapid recombinations inside the HeIII-fossils will be more common. Our model of inhomogeneous recombination also applies to "double reionization'' models and shows that a non-monotonic reionization history is even more unlikely than previously thought.

Steven Furlanetto; Zoltan Haiman; S. Peng Oh

2008-03-24

431

The Great Fossil Fiasco: Teaching about Peer Review.  

ERIC Educational Resources Information Center

Describes a lesson that engages middle school students in learning about peer review. Uses the article "Archaeoraptor Fossil Trail," which was published in the November, 1999 issue of "National Geographic" as an example of a real life story of how peer review forces scientists to critically re-examine a fossil discovery. (SOE)

Gift, Nancy; Krasny, Marianne

2003-01-01

432

Fossil fuel decarbonization technology for mitigating global warming  

Microsoft Academic Search

It has been understood that production of hydrogen from fossil and carbonaceous fuels with reduced CO2 emission to the atmosphere is key to the production of hydrogen-rich fuels for mitigating the CO2 greenhouse gas climate change problem. The conventional methods of hydrogen production from fossil fuels (coal, oil, gas and biomass) include steam reforming and water gas shift mainly of

M Steinberg

1999-01-01

433

Strontium in Fossil Bones and the Reconstruction of Food Chains  

Microsoft Academic Search

The strontium content of bone is a function of the strontium content of the ingested food. Under favorable conditions of fossilization it can be used for the determination of feeding habits of extinct terrestrial vertebrates. Homogeneous samples of fossil biotic communities are a prerequisite for significant results.

Heinrich Toots; M. R. Voorhies

1965-01-01

434

Fossil weevils (Coleoptera: Curculionidae) from latitude 85°S Antarctica  

Microsoft Academic Search

Two species of fossil listroderine weevils (Coleoptera: Curculionidae: Rhytirhinini: Listroderina) are reported from the Meyer Desert Formation at a locality on the Beardmore Glacier in the Transantarctic Mountains about 500 km from the South Pole. Associated fossils include wood, leaves and pollen of Nothofagus, stems and leaves of several species of mosses, achenes of Ranunculus, shells of freshwater molluscs and

Allan C. Ashworth; Guillermo Kuschel

2003-01-01

435

The buzz on bees: Oldest bee fossil found  

NSDL National Science Digital Library

Scientists reported finding the oldest fossil of a honey bee. It is 100 million years old. This fossil is about 40 millions years older than ones found before. Scientists will use the bee to understand how bees developed over history and how bees contributed to rapid changes in green plants.

American Association for the Advancement of Science (AAAS; )

2006-10-26

436

World catalog of extant and fossil Corethrellidae (Diptera).  

PubMed

A world catalog of extant and fossil frog-biting midges (Diptera: Corethrellidae) provides full type information, known life stages, and distribution of each species. There are 105 extant and seven fossil species of Corethrellidae but unnamed species are known from Costa Rica, Colombia and Madagascar. New information on types and other important specimens are provided. PMID:24870687

Borkent, Art

2014-01-01

437

BRITISH FOSSIL INSECTS. By T. D. A. COCKERELL,  

E-print Network

BRITISH FOSSIL INSECTS. By T. D. A. COCKERELL, Of the University of Colorado, Boulder. INTRODUCTION OF OCCURRENCES. It seems useful to present a brief summary of our knowledge of British fossil insects up im- perfect to be accurately classified. The British Mesozoic insects, especially those from the Lias

Villemant, Claire

438

Fossil fuel decarbonization technology for mitigating global warming  

Microsoft Academic Search

It has been understood that production of hydrogen from fossil and carbonaceous fuels with reduced COâ emission to the atmosphere is key to the production of hydrogen-rich fuels for mitigating the COâ greenhouse gas climate change problem. The conventional methods of hydrogen production from fossil fuels (coal, oil, gas and biomass) include steam reforming and water gas shift mainly of

Steinberg

1998-01-01

439

Modeling Seasonality in Carbon Dioxide Emissions From Fossil Fuel Consumption  

Microsoft Academic Search

Using United States data, a method is developed to estimate the monthly consumption of solid, liquid and gaseous fossil fuels using monthly sales data to estimate the relative monthly proportions of the total annual national fossil fuel use. These proportions are then used to estimate the total monthly carbon dioxide emissions for each state. From these data, the goal is

P. Kishore; K. Igarashi; H. Oikawa; M. Uotome; J. S. Gregg; R. J. Andres

2004-01-01

440

Alternative energy: Can renewable energy sources replace fossil fuels  

Microsoft Academic Search

Fossil fuels have been the prime mover of industrial life for some 200 years. The burning of coal and oil have saved inestimable amounts of time and labor while substantially raising living standards around the world. But many scientists now say the use of fossil fuels, which account for 85% of US energy use, contributes to global warming and could

1992-01-01

441

Introduction Fossil fuel combustion by aviation, shipping and road  

E-print Network

96 Introduction Fossil fuel combustion by aviation, shipping and road traffic contributes about one. here we summarize some of the first findings. Emissions by transport modes Emissions from fossil fuel to global CO emissions are estimated to be much smaller, likely due to more efficient fuel combustion. Road

Haak, Hein

442

Environmental Law and Fossil Fuels: Barriers to Renewable Energy  

E-print Network

This article is concerned with renewable energy’s too-slow transition and with how existing legal regimes work to preserve fossil energy dominance. It develops from two related claims: that an implicit support structure for fossil energy is written...

Outka, Uma

2012-01-01

443

Morphology, fossils, divergence timing, and the phylogenetic relationships of Gavialis.  

PubMed

Although morphological data have historically favored a basal position for the Indian gharial (Gavialis gangeticus) within Crocodylia and a Mesozoic divergence between Gavialis and all other crocodylians, several recent molecular data sets have argued for a sister-group relationship between Gavialis and the Indonesian false gharial (Tomistoma schlegelii) and a divergence between them no earlier than the Late Tertiary. Fossils were added to a matrix of 164 discrete morphological characters and subjected to parsimony analysis. When morphology was analyzed alone, Gavialis was the sister taxon of all other extant crocodylians whether or not fossil ingroup taxa were included, and a sister-group relationship between Gavialis and Tomistoma was significantly less parsimonious. In combination with published sequence and restriction site fragment data, Gavialis was the sister taxon of all other living crocodylians, but the position of Tomistoma depended on the inclusion of fossil ingroup taxa; with or without fossils, preferred morphological and molecular topologies were not significantly different. Fossils closer to Gavialis than to Tomistoma can be recognized in the Late Cretaceous, and fossil relatives of Tomistoma are known from the basal Eocene, strongly indicating a divergence long before the Late Tertiary. Comparison of minimum divergence time from the fossil record with different measures of molecular distance indicates evolutionary rate heterogeneity within Crocodylia. Fossils strongly contradict a post-Oligocene divergence between Gavialis and any other living crocodylian, but the phylogenetic placement of Gavialis is best viewed as unresolved. PMID:11975331

Brochu, C A

1997-09-01

444

Body size of insular carnivores: evidence from the fossil record  

E-print Network

SPECIAL ISSUE Body size of insular carnivores: evidence from the fossil record George A. Lyras1 carnivores on islands; (2) offer causal explanations for this pattern and deviations from it ­ as far as fossil carnivores are concerned; and (3) estimate the speed of this trend. Location Oceanic and oceanic

Binford, Michael W.

445

On the Optimum Trend of Fossil Fuel Taxation  

Microsoft Academic Search

The interest rate should fall with global warming. Remedial policy should allow for this endogeneity. In the simplest infinite-horizon model yielding a steady-state, one can derive the trend that an ad valorem fossil fuel tax should take to internalize the externality from emissions. It is negative. If implemented, it would reduce fossil fuel depletion and raise the rates of interest

Peter J N Sinclair

1994-01-01

446

Reducing CO 2 emissions by substituting biomass for fossil fuels  

Microsoft Academic Search

Replacing fossil fuels with sustainably-produced biomass will reduce the net flow of CO2 to the atmosphere. We express the efficiency of this substitution in reduced emissions per unit of used land or biomass and in costs of the substitution per tonne of C. The substitution costs are calculated as the cost difference between continued use of fossil fuels at current

Leif Gustavsson; Pål Börjesson; Bengt Johansson; Per Svenningsson

1995-01-01

447

Fossil Fuel Combustion and the Major Sedimentary Cycle  

Microsoft Academic Search

The combustion of the fossil fuels coal, oil, and lignite potentially can mobilize many elements into the atmosphere at rates, in general, less than but comparable to their rates of flow through natural waters during the weathering cycle. Since the principal sites of fossil fuel combustion are in the mid-latitudes of the Northern Hemisphere, changes in the composition of natural

K. K. Bertine; Edward D. Goldberg

1971-01-01

448

Emissions from ethanol-blended fossil fuel flames  

Microsoft Academic Search

A fundamental study to investigate the emission characteristics of ethanol-blended fossil fuels is presented. Employing a heterogeneous experimental setup, emissions are measured from diffusion flames around spherical porous particles. Using an infusion pump, ethanol-fossil fuel blend is transpired into a porous sphere kept in an upward flowing air stream. A typical probe of portable digital exhaust gas analyzer is placed

Akcayoglu; Azize

2011-01-01

449

Emissions from ethanol-blended fossil fuel flames  

Microsoft Academic Search

A fundamental study to investigate the emission characteristics of ethanol-blended fossil fuels is presented. Employing a heterogeneous experimental setup, emissions are measured from diffusion flames around spherical porous particles. Using an infusion pump, ethanol–fossil fuel blend is transpired into a porous sphere kept in an upward flowing air stream. A typical probe of portable digital exhaust gas analyzer is placed

Shintre Parag; Karnam Bhadraiah; Vasudevan Raghavan

2011-01-01

450

Answers to the Activities Amber Fossil's Living Relative  

E-print Network

Answers to the Activities Amber Fossil's Living Relative Butterfly B is the closest living relative. It is Voltinia danforthi, a metalmark native to Mexico. It is the only butterfly sharing both characteristics with the fossil specimen. 1) It has a continuous ring of brown eye scales, and 2) the same brown colored palpi

Mathis, Wayne N.

451

Storage and release of fossil organic carbon related to weathering of sedimentary rocks  

E-print Network

Storage and release of fossil organic carbon related to weathering of sedimentary rocks Yoann of various mineral and organic carbon forms. Among these carbon forms, fossil organic carbon (FOC) (i basins; weathering; fossil organic carbon flux; fossil organic carbon storage #12;1. Introduction Fossil

Paris-Sud XI, Université de

452

Fossils of the Gault Clay and Folkestone Beds of Kent, UK  

NSDL National Science Digital Library

A diverse collection of lower Cretaceous (Albian) fossils is featured on this site. Fossil photos, illustrations and information about each suborder are provided for an array of fossil groups. Specific fossil groups include Ammonoidea, Bivalvia, Cephalopoda, Cnidaria (Corals), Echinodermata, Fish, Foraminifera, Gastropoda, Ostracoda, and Scaphopoda. Short discussions of United Kingdom geology, Albian stratigraphy, geologic time and fossil imaging techniques are also included.

Fred, Clouter

453

An unusual mechanism for HOMO-LUMO gap narrowing in a minimal near-IR dye generated by the deprotonation of bis(dicyanomethylene)indan  

NASA Astrophysics Data System (ADS)

A minimal near-IR (NIR) dye with the lower molecular-weight than 250 is produced by the deprotonation of 1,3-bis(dicyanomethylene)indan. Despite the small ?-conjugation system, the anionic dye shows light absorption and fluorescence in the red to near infra-red region. This Letter reports on the unusual mechanism for HOMO-LUMO gap narrowing for the NIR dye. Density functional theory (DFT) analyses show the molecular-orbital transition from the LUMO+1 to HOMO by the deprotonation, which significantly reduces the HOMO-LUMO gap. Time-dependent DFT and group-theory analyses well explain the electronic-excitation properties. This is a new mechanism for reducing a HOMO-LUMO gap without extending ?-conjugation systems.

Fujisawa, Jun-ichi

2014-07-01

454

INVESTIGATION OF THE CORRELATION BETWEEN THE ENERGY OF THE HIGHESTOCCUPIED MOLECULAR ORBITAL (HOMO) AND THE LOGARITHM OF THE OH RATECONSTANT OF HYDROFLUOROCARBONS AND HYDROFLUOROETHERS  

EPA Science Inventory

A regression based model was developed to determine whether highest occupied molecular orbital (HOMO) energies, calculated using Kohn-Sham orbital density functional theory (DFT) could be used to estimate the OH rate constants of hydrofluorocarbons (HFCS) and hydrofluoroethers (H...

455

A DNA-templated silver nanocluster probe for label-free, turn-on fluorescence-based screening of homo-adenine binding molecules.  

PubMed

A novel, label-free, turn-on fluorescence strategy to detect molecules that bind to adenine-rich DNA sequences has been developed. The probe employs DNA-templated silver nanoclusters (DNA-AgNCs) as the key detection component. The new strategy relies on the formation of non-Watson-Crick homo-adenine DNA duplex, triggered by strong interactions with homo-adenine binding molecules, which brings a guanine-rich sequence in one strand close to DNA-AgNCs located on the opposite strand. This phenomenon transforms weakly fluorescent AgNCs into highly emissive species that display bright red fluorescence. Finally, we have shown that the new fluorescence turn-on strategy can be employed to detect coralyne, the most representative homo-adenine binding molecule that triggers formation of a non-Watson-Crick homo-adenine DNA duplex. PMID:25441410

Park, Ki Soo; Park, Hyun Gyu

2015-02-15

456

The earliest fossil record of the animals and its significance.  

PubMed

The fossil record of the earliest animals has been enlivened in recent years by a series of spectacular discoveries, including embryos, from the Ediacaran to the Cambrian, but many issues, not least of dating and interpretation, remain controversial. In particular, aspects of taphonomy of the earliest fossils require careful consideration before pronouncements about their affinities. Nevertheless, a reasonable case can now be made for the extension of the fossil record of at least basal animals (sponges and perhaps cnidarians) to a period of time significantly before the beginning of the Cambrian. The Cambrian explosion itself still seems to represent the arrival of the bilaterians, and many new fossils in recent years have added significant data on the origin of the three major bilaterian clades. Why animals appear so late in the fossil record is still unclear, but the recent trend to embrace rising oxygen levels as being the proximate cause remains unproven and may even involve a degree of circularity. PMID:18192192

Budd, Graham E

2008-04-27

457

Divergence time estimates of mammals from molecular clocks and fossils: Relevance of new fossil finds from India  

Microsoft Academic Search

This paper presents a brief review of recent advances in the classification of mammals at higher levels using fossils and\\u000a molecular clocks. It also discusses latest fossil discoveries from the Cretaceous — Eocene (66–55 m.y.) rocks of India and\\u000a their relevance to our current understanding of placental mammal origins and diversifications.

G. V. R. Prasad

2009-01-01

458

Fossils and tFossils and the Rock Cyclehe Rock Cycle The rock cycle explains how one type of rock  

E-print Network

1 Fossils and tFossils and the Rock Cyclehe Rock Cycle h ^ The rock cycle explains how one type of rock can be transformed into another in nature. The Geologic Cycle 3 key events: deposition, uplift geologic time Forms Strata: layers of rock The rock cycle explains how one type of rock can be transformed

Cochran-Stafira, D. Liane

459

Fossil Fuels Research Matrix Program. US Environmental Protection Agency\\/Department of Energy Fossil Fuels Research Materials Facility  

Microsoft Academic Search

The Fossil Fuels Research Materials Facility was established by an Interagency Agreement between the US EPA and US DOE to provide support for health and environmental-effects studies of alternate fossil fuels technologies. The Facility provides a common source of a wide range of samples which can be drawn upon for methods development and evaluation, interlaboratory comparison, or determination of chemical

W. H. Griest; M. R. Guerin

1980-01-01

460

Fossil Energy R&D at Oak Ridge National Laboratory The Oak Ridge National Laboratory's Fossil Energy Program conducts research and development that  

E-print Network

Fossil Energy R&D at Oak Ridge National Laboratory The Oak Ridge National Laboratory's Fossil Energy Program conducts research and development that contribute to the advancement of fossil energy and technologies for the sustainable production and use of fossil energy resources. ORNL works with the US

461

Direct homo- and hetero-interactions of MeCP2 and MBD2.  

PubMed

Epigenetic marks like methylation of cytosines at CpG dinucleotides are essential for mammalian development and play a major role in the regulation of gene expression and chromatin architecture. The methyl-cytosine binding domain (MBD) protein family recognizes and translates this methylation mark. We have recently shown that the level of MeCP2 and MBD2, two members of the MBD family, increased during differentiation and their ectopic expression induced heterochromatin clustering in vivo. As oligomerization of these MBD proteins could constitute a factor contributing to the chromatin clustering effect, we addressed potential associations among the MBD family performing a series of different interaction assays in vitro as well as in vivo. Using recombinant purified MBDs we found that MeCP2 and MBD2 showed the stronger self and cross association as compared to the other family members. Besides demonstrating that these homo- and hetero-interactions occur in the absence of DNA, we could confirm them in mammalian cells using co-immunoprecipitation analysis. Employing a modified form of the fluorescent two-hybrid protein-protein interaction assay, we could clearly visualize these associations in single cells in vivo. Deletion analysis indicated that the region of MeCP2 comprising amino acids 163-309 as well the first 152 amino acids of MBD2 are the domains responsible for MeCP2 and MBD2 associations. Our results strengthen the possibility that MeCP2 and MBD2 direct interactions could crosslink chromatin fibers and therefore give novel insight into the molecular mechanism of MBD mediated global heterochromatin architecture. PMID:23335972

Becker, Annette; Allmann, Lena; Hofstätter, Maria; Casà, Valentina; Weber, Patrick; Lehmkuhl, Anne; Herce, Henry D; Cardoso, M Cristina

2013-01-01

462

The origins and persistence of Homo floresiensis on Flores: biogeographical and ecological perspectives  

NASA Astrophysics Data System (ADS)

The finding of archaeological evidence predating 1 Ma and a small hominin species (Homo floresiensis) on Flores, Indonesia, has stimulated much research on its origins and ancestry. Here we take a different approach and examine two key questions - 1) how did the ancestors of H. floresiensis reach Flores and 2) what are the possibilities for estimating the likelihood of hominin persistence for over 1 million years on a small island? With regard to the first question, on the basis of the biogeography we conclude that the mammalian, avian, and reptilian fauna on Flores arrived from a number of sources including Java, Sulawesi and Sahul. Many of the terrestrial taxa were able to float or swim (e.g. stegodons, giant tortoises and the Komodo dragon), while the rodents and hominins probably accidentally rafted from Sulawesi, following the prevailing currents. The precise route by which hominins arrived on Flores cannot at present be determined, although a route from South Asia through Indochina, Sulawesi and hence Flores is tentatively supported on the basis of zoogeography. With regards to the second question, we find the archaeological record equivocal. A basic energetics model shows that a greater number of small-bodied hominins could persist on Flores than larger-bodied hominins (whether H. floresiensis is a dwarfed species or a descendent of an early small-bodied ancestor is immaterial here), which may in part explain their apparent long-term success. Yet the frequent tsunamis and volcanic eruptions in the region would certainly have affected all the taxa on the island, and at least one turnover event is recorded, when Stegodon sondaari became extinct. The question of the likelihood of persistence may be unanswerable until we know much more about the biology of H. floresiensis.

Dennell, Robin W.; Louys, Julien; O'Regan, Hannah J.; Wilkinson, David M.

2014-07-01

463

PET and MRI show differences in cerebral asymmetry and functional connectivity between homo- and heterosexual subjects  

PubMed Central

Cerebral responses to putative pheromones and objects of sexual attraction were recently found to differ between homo- and heterosexual subjects. Although this observation may merely mirror perceptional differences, it raises the intriguing question as to whether certain sexually dimorphic features in the brain may differ between individuals of the same sex but different sexual orientation. We addressed this issue by studying hemispheric asymmetry and functional connectivity, two parameters that in previous publications have shown specific sex differences. Ninety subjects [25 heterosexual men (HeM) and women (HeW), and 20 homosexual men (HoM) and women (HoW)] were investigated with magnetic resonance volumetry of cerebral and cerebellar hemispheres. Fifty of them also participated in PET measurements of cerebral blood flow, used for analyses of functional connections from the right and left amygdalae. HeM and HoW showed a rightward cerebral asymmetry, whereas volumes of the cerebral hemispheres were symmetrical in HoM and HeW. No cerebellar asymmetries were found. Homosexual subjects also showed sex-atypical amygdala connections. In HoM, as in HeW, the connections were more widespread from the left amygdala; in HoW and HeM, on the other hand, from the right amygdala. Furthermore, in HoM and HeW the connections were primarily displayed with the contralateral amygdala and the anterior cingulate, in HeM and HoW with the caudate, putamen, and the prefrontal cortex. The present study shows sex-atypical cerebral asymmetry and functional connections in homosexual subjects. The results cannot be primarily ascribed to learned effects, and they suggest a linkage to neurobiological entities. PMID:18559854

Savic, Ivanka; Lindström, Per

2008-01-01

464

Structure and spectroscopic studies of homo-and heterometallic complexes of adipic acid dihydrazide  

NASA Astrophysics Data System (ADS)

A single crystal of adipic acid dihydrazide, ADH, has been analyzed. Its reaction with Co2+, Ni2+, Cu2+, Zn2+, Cd2+, Hg2+, Ag+, Pd2+ and/or Pt2+ gave homometallic and heterometallic complexes which are characterized by partial elemental analysis, spectra (MS, ESR, 1H NMR, electronic; IR), thermal analysis and magnetic measurements. Some complexes: Zn0.73Cu(ADH)Cl4·H2O; Zn0.71Hg0.36(ADH)Cl4·H2O; Zn0.65Cd0.46(ADH)Cl4·½H2O; Zn0.75Co0.41(ADH-2H)Cl2·3H2O; Cd0.85Co0.43(ADH)Cl4·½EtOH were isolated having nonstiochiometric metal ratios. The ligand behaves as a neutral (bidentate or tetradentate) and/or binegative tetradentate. A square-pyramid, square-planar and tetrahedral structures were proposed for the homo Co(II), Cu(II) and Ni(II) complexes, respectively. A similar and different stereochemistry around each metal ion (tetrahedral + tetrahedral; tetrahedral + square-planar; tetrahedral + tetrahedral and/or tetrahedral + octahedral) was suggested for the heterometallic complexes. Some complexes were found highly stable with stability point >240 °C; the most stable is [HgNi(ADH-2H)Cl2]. The presence of diamagnetic atom (Zn, Cd or Hg) reduces the magnetic moments and gave anomalous moments. The degradation steps and the hydrated complexes are confirmed through the TGA study. The order of covalency of [Zn0.73Cu(ADH)Cl4]·H2O, [CdCu(ADH)Cl4]·H2O and [HgCu(ADH-2H)Cl2] matches with the size of the second metal (Zn complex > Cd complex > Hg complex). Some heterometallic complexes were found nonstoichiometric through the analysis of their metal content and supported by TGA.

Jeragh, Bakir; El-Asmy, Ahmed A.

465

Sedimentation analysis of novel DNA structures formed by homo-oligonucleotides.  

PubMed

Sedimentation velocity analysis has been used to examine the base-specific structural conformations and unusual hydrogen bonding patterns of model oligonucleotides. Homo-oligonucleotides composed of 8-28 residues of dA, dT, or dC nucleotides in 100 mM sodium phosphate, pH 7.4, at 20 degrees C behave as extended monomers. Comparison of experimentally determined sedimentation coefficients with theoretical values calculated for assumed helical structures show that dT and dC oligonucleotides are more compact than dA oligonucleotides. For dA oligonucleotides, the average width (1.7 nm), assuming a cylindrical model, is smaller than for control duplex DNA whereas the average rise per base (0.34 nm) is similar to that of B-DNA. For dC and dT oligonucleotides, there is an increase in the average widths (1.8 nm and 2.1 nm, respectively) whereas the average rise per base is smaller (0.28 nm and 0.23 nm, respectively). A significant shape change is observed for oligo dC(28) at lower temperatures (10 degrees C), corresponding to a fourfold decrease in axial ratio. Optical density, circular dichroism, and differential scanning calorimetry data confirm this shape change, attributable from nuclear magnetic resonance analysis to i-motif formation. Sedimentation equilibrium studies of oligo dG(8) and dG(16) reveal extensive self-association and the formation of G-quadruplexes. Continuous distribution analysis of sedimentation velocity data for oligo dG(16) identifies the presence of discrete dimers, tetramers, and dodecamers. These studies distinguish the conformational and colligative properties of the individual bases in DNA and their inherent capacity to promote specific folding pathways. PMID:11423421

Hatters, D M; Wilson, L; Atcliffe, B W; Mulhern, T D; Guzzo-Pernell, N; Howlett, G J

2001-07-01

466

CHARACTERIZING MODERN AND FOSSIL GYMNOSPERM EXUDATES USING MICRO-FOURIER TRANSFORM INFRARED SPECTROSCOPY  

E-print Network

CHARACTERIZING MODERN AND FOSSIL GYMNOSPERM EXUDATES USING MICRO-FOURIER TRANSFORM INFRARED spectroscopy have direct implications for the assessment of the fossil potential and the chemotaxonomic interpretation of modern and fossil gymnosperm exudates. Keywords: chemotaxonomy, plant resin, gum, conifers

Wolfe, Alexander P.

467

43 CFR 8224.1 - Use of the Fossil Forest Research Natural Area.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 false Use of the Fossil Forest Research Natural Area. 8224.1 Section...RECREATION PROGRAMS PROCEDURES Fossil Forest Research Natural Area § 8224.1 Use of the Fossil Forest Research Natural Area....

2013-10-01

468

43 CFR 8224.1 - Use of the Fossil Forest Research Natural Area.  

Code of Federal Regulations, 2012 CFR

...2012-10-01 false Use of the Fossil Forest Research Natural Area. 8224.1 Section...RECREATION PROGRAMS PROCEDURES Fossil Forest Research Natural Area § 8224.1 Use of the Fossil Forest Research Natural Area....

2012-10-01

469

43 CFR 8224.1 - Use of the Fossil Forest Research Natural Area.  

Code of Federal Regulations, 2011 CFR

...2011-10-01 false Use of the Fossil Forest Research Natural Area. 8224.1 Section...RECREATION PROGRAMS PROCEDURES Fossil Forest Research Natural Area § 8224.1 Use of the Fossil Forest Research Natural Area....

2011-10-01

470

43 CFR 8224.1 - Use of the Fossil Forest Research Natural Area.  

...2014-10-01 false Use of the Fossil Forest Research Natural Area. 8224.1 Section...RECREATION PROGRAMS PROCEDURES Fossil Forest Research Natural Area § 8224.1 Use of the Fossil Forest Research Natural Area....

2014-10-01

471

76 FR 3517 - Standards of Performance for Fossil-Fuel-Fired, Electric Utility, Industrial-Commercial...  

Federal Register 2010, 2011, 2012, 2013

...2060-AQ46 Standards of Performance for Fossil-Fuel-Fired, Electric Utility, Industrial-Commercial-Institutional...221112 Fossil fuel-fired electric utility steam...22112 Fossil fuel-fired electric utility...

2011-01-20

472

75 FR 66008 - Fossil Fuel-Generated Energy Consumption Reduction for New Federal Buildings and Major...  

Federal Register 2010, 2011, 2012, 2013

...EERE-2010-BT-STD-0031] RIN 1904-AB96 Fossil Fuel-Generated Energy Consumption...rulemaking (NOPR) regarding the fossil fuel- generated energy consumption...seeking comments regarding the fossil fuel-generated energy...

2010-10-27

473

78 FR 9016 - Approval and Promulgation of Air Quality Implementation Plans; Massachusetts; Revisions to Fossil...  

Federal Register 2010, 2011, 2012, 2013

...Massachusetts; Revisions to Fossil Fuel Utilization and Source Registration...testing requirements for certain fossil fuel utilization facilities, rename...approval of the state's revised fossil fuel utilization facility...

2013-02-07

474

78 FR 44103 - Announcement of Public Meetings To Receive Comments on Draft Solicitation for Advanced Fossil...  

Federal Register 2010, 2011, 2012, 2013

...Regulations), and (3) use advanced fossil energy technology (within the meaning...solicitation would be broad. All fossil fuels, including, without limitation...both electrical and non-electrical fossil energy use. While comments are...

2013-07-23

475

Fossil fungi with suggested affinities to the Endogonaceae from the Middle Triassic of Antarctica  

E-print Network

Documented fossil evidence of zygomycetous fungi is rare. A conspicuous fungal fossil, Jimwhitea circumtecta gen. et sp. nov., occurs in permineralized peat from the Middle Triassic of Antarctica. The fossil is interpreted as a mantled...

Krings, Michael; Taylor, Thomas N.; Dotzler, Nora; Persichini, Gianna

2012-07-01

476

Amino acids in modern and fossil woods  

NASA Technical Reports Server (NTRS)

The amino acid composition and the extent of racemization in several modern and fossil woods are reported. The method of analysis is described, and data are presented on the total amino acid concentration, the amino acid ratios, and the enantiomeric ratios in each sample. It is found that the amino acid concentration per gram of dry wood decreases with age of the sample, that the extent of racemization increases with increasing age, and that the amounts of aspartic acid, threonine, and serine decrease relative to valine with increasing age. The relative racemization rates of amino acids in wood, bone, and aqueous solution are compared, and it is shown that racemization in wood is much slower than in bone or aqueous solution. Racemization results for woods from the Kalambo Falls area of Zambia are used to calculate a minimum age of 110,000 years for the transition between the Sangoan and Acheulian industries at that site. This result is shown to be consistent with numerous radiometric dates for older Acheulian sites in Africa and to compare well with geologically inferred dates for the beginning of the Eemian and the end of the Acheulian industry in southern Africa.

Lee, C.; Bada, J. L.; Peterson, E.

1976-01-01

477

Modeling neck mobility in fossil turtles.  

PubMed

Turtles have the unparalleled ability to retract their heads and necks within their shell but little is known about the evolution of this trait. Extensive analysis of neck mobility in turtles using radiographs, CT scans, and morphometry reveals that basal turtles possessed less mobility in the neck relative to their extant relatives, although the anatomical prerequisites for modern mobility were already established. Many extant turtles are able to achieve hypermobility by dislocating the central articulations, which raises cautions about reconstructing the mobility of fossil vertebrates. A 3D-model of the Late Triassic turtle Proganochelys quenstedti reveals that this early stem turtle was able to retract its head by tucking it sideways below the shell. The simple ventrolateral bend seen in this stem turtle, however, contrasts with the complex double-bend of extant turtles. The initial evolution of neck retraction therefore occurred in a near-synchrony with the origin of the turtle shell as a place to hide the unprotected neck. In this early, simplified retraction mode, the conical osteoderms on the neck provided further protection. J. Exp. Zool. (Mol. Dev. Evol.) 9999B: XX-XX, 2014. © 2014 Wiley Periodicals, Inc. PMID:24497449

Werneburg, Ingmar; Hinz, Juliane K; Gumpenberger, Michaela; Volpato, Virginie; Natchev, Nikolay; Joyce, Walter G

2014-02-01

478

Catching the fossil fuel biodesulfurization wave  

SciTech Connect

Both coal and oil contain sulfur atoms covalently bound to the carbon skeleton of the fuel. This organic sulfur is located in more complex and more polycyclo-aromatic structures in coals than in petroleum and is modeled (albeit not perfectly) by the simple aromatic compound dibenzothiophene (DBT). Coals, but not petroleum, also contain inorganic forms of sulfur. These are various iron sulfides, most notably iron pyrites. Unlike organic sulfur, inorganic sulfur is not chemically bound to the carbon matrix of coal and can be removed, at least partially, by physical means that depend on differences in density and hydrophobicity between coal and pyrites. Throughout the 1970s and 1980s, DOE/PETC was active in promoting advanced physical methods of coal cleaning and had invested considerable money, effort, and prestige in their development. To address that other coal-sulfur problem--the organic sulfur component--DOE/PETC funded a range of chemistry-based options through the early 1990s. By the early 1980s, and in the wake of the coming of age of genetic engineering, microbially based processes were beginning to make an appearance on the industrial scene. Coal cleaning was no exception. The author discusses his perceptions of the DOE's foray into fossil fuel biodesulfurization.

Campbell, I.M. (Univ. of Pittsburgh, PA (United States))

1993-10-01

479

On the Nature of Fossil Galaxy Groups: Are they really fossils ?  

E-print Network

We use SDSS-DR4 photometric and spectroscopic data out to redshift z~0.1 combined with ROSAT All Sky Survey X-ray data to produce a sample of twenty-five fossil groups (FGs), defined as bound systems dominated by a single, luminous elliptical galaxy with extended X-ray emission. We examine possible biases introduced by varying the parameters used to define the sample and the main pitfalls are discussed. The spatial density of FGs, estimated via the V/V_ MAX} test, is 2.83 x 10^{-6} h_{75}^3 Mpc^{-3} for L_x > 0.89 x 10^42 h_{75}^-2 erg/s consistent with Vikhlinin et al. (1999), who examined an X-ray overluminous elliptical galaxy sample (OLEG). We compare the general properties of FGs identified here with a sample of bright field ellipticals genera