bluuebunny/crossref_metadata_2025 huggingface dataset:
Plant and Insect Fossils at Norwood in South-Central Minnesota: A Record of Late-Glacial Succession
Authors: Ashworth Allan C. , Schwert Donald P. , Watts William A. , Wright H.E.
Published: December 2004

The Norwood site in Sibley Co., Minnesota, contains 1.6 m of silt resting on till and overlain by peat. The base of the peat has been radiocarbon dated at 12,400 ± 60 and the top at 11,200 ± 250 yr B.P. The pollen, plant macrofossils, and insect remains in the basal silt consist of boreal species inhabiting open environments, but not tundra. No modern analogue exists for the insect assemblage, which includes elements of boreal forest, tundra-forest, and western affinities. The transition from an unstable open environment to a stable coniferous forest is reflected by both plant and insect fossils and is interpreted as a successional rather than a climatic event. During this time of significant biologic change, the climate is inferred to have been relatively uniform, with temperatures similar to those presently existing in the boreal forest south of the tundra-forest transition zone. The geologic and ecologic succession at Norwood is generally similar to that presently associated with ice stagnation of the Klutlan Glacier in the Yukon Territory. Localized successional sequences similar to those at Norwood are conceived to have occurred repeatedly during the melting of the Laurentide ice, and thus the proposed model has potentially broad application to the interpretation of late-glacial sequences.
Benthonic Foraminiferal Faunal and Isotopic Data for the Postglacial Evolution of the Champlain Sea
Authors: Corliss Bruce H. , Hunt Allen S. , Keigwin Lloyd D.
Published: December 2004

Benthonic foraminiferal faunal and isotopic data from Champlain Sea sediments (approximately 12,500 to 10,000 yr B.P. in age) in two piston cores from Lake Champlain provide a detailed, apparently continuous record of the evolution of the Champlain Sea. Cassidulina reniforme and Islandiella helenae are the dominant benthonic foraminifera during the initial phase of the Champlain Sea, and are replaced by Elphidium excavatum forma clavatum and Protelphidium orbiculare as the dominant species during the remainder of the sea's history. The oxygen-isotopic data show a gradual decrease in δ18O between approximately 12,500 and 10,900 yr B.P., followed by a more rapid decrease during the interval 10,900 to 10,000 yr B.P. The δ13C data have a similar trend as δ18O, with generally decreasing values up the section. The isotopic and faunal data suggest that nearly marine conditions were present in the initial plase of the Champlain Sea, followed by gradually decreasing salinities and increasing temperatures as the sea evolved. The beginning of the rapid isotopic decrease at approximately 10,900 yr B.P. marks the onset of the largest environmental change in the history of the Champlain Sea, probably reflecting a major pulse of meltwater from the Laurentide Ice Sheet.
Late Quaternary Environments and Biogeography in the Great Basin
Authors: Thompson R. S. , Mead J. I.
Published: December 2004

Plant and animal remains found in packrat (Neotomaspp.) middens and cave fill from the eastern and southern Great Basin region reveal the presence of subalpine conifers and boreal mammals at relatively low elevations during the Late Wisconsin. Limber pine (Pinus flexilis) and bristlecone pine (P. longaeva) were important in the late Pleistocene plant communities throughout this region. Spruce (Piceacf.engelmannii) and common juniper (Juniperus communis) were present in some of the more northerly localities, and Douglas fir (Pseudotsuga menziesii) and white fir (Abies concolor) were present in southern and eastern localities. Single needle pinyon pine (Pinus monophylla), common across this region today, was apparently not present north of the Sheep Range of southern Nevada during the Late Wisconsin. Pikas (Ochotonacf.princeps), small boreal mammals present in only a few Great Basin mountain ranges today, were common throughout the region. Heather voles (Phenacomyscf.intermedius) have been found in two cave fill deposits in Nevada, though they are unknown in the Great Basin today. Limber and bristlecone pines are generally restricted to rocky substrates in modern subalpine habitats in the Great Basin, and this may also have been the case when these plants grew at lower elevations during the Late Wisconsin. Subalpine conifers were present on the rock outcrops sampled by the packrat middens, but shrub communities, perhaps dominated by sagebrush (Artemisiaspp.), may have been present on alluvial valley-bottom substrates. Forested habitats would thus have been isolated habitat islands, as they are today. Boreal small mammals, including pikas and heather voles, were able to colonize the Great Basin mountain ranges during the late Pleistocene. We suggest that these mammals were able to survive in the intervening valley-bottoms under a cool-summer climatic regime, and that continuous forest or woodland corridors were not necessary for migration.
The Timing of Late Pleistocene Mammalian Extinctions in North America
Authors: Meltzer David J. , Mead Jim I.
Published: December 2004

More than 375 14C dates from 150 fossil sites in North America have been analyzed to evaluate the question of extinction of Late Pleistocene megafauna. When critically evaluated, no 14C ages for any extinct Pleistocene genera are younger than 10,000 yr B.P.
Late Quaternary Insects of Rancho La Brea and McKittrick, California
Authors: Miller Scott E.
Published: December 2004

Asphalt-impregnated sediments at Rancho La Brea (Los Angeles County) and McKittrick (Kern County) in California provide a rich Quaternary insect record. Ages of various sites at Rancho La Brea range from more than 40,00014C yr B.P. to modern. McKittrick insects studied by W. D. Pierce are not contemporaneous with the late Pleistocene vertebrate fauna, but are only about 700014C yr old. The major paleoecological groupings are: (1) ground dwellers, (2) aquatics. (3) scavengers, and (4) miscellaneous. Contrary to conclusions of earlier authors, most specimens represent modern species. Only two apparent terminal Pleistocene extinctions are recognized. both dung beetles (Scarabaeidae).
Sea-level Data for Parts of the Bering-Chukchi Shelves of Beringia from 19,000 to 10,000 14C yr B.P.
Authors: McManus Dean A. , Creager Joe S.
Published: December 2004

Sea-level changes in Beringia are especially significant because they affect the migration of land plants and animals between Asia and North America, and marine plants and animals between the Pacific and Arctic oceans. Previous studies of cores from the Bering and Chukchi shelves produced sea-level curves. Evaluation of these data suggests that nine of the radiocarbon-dated estimates of sea-level position are most reliable for the time period 19,000 to 10,000 yr B.P. The trend of these nine points is proposed as the basis for a regional sea-level curve for central Beringia. Constraints on the data must be noted, however, by anyone using them.
Dating Indian Corals by U-Decay-Series Methods
Authors: Somayajulu B. L. K. , Broecker W. S. , Goddard J.
Published: December 2004

Nine samples of corals collected from seven locations in the Saurashtra Coastal region of India were dated by 238U series disequilibrium methods. Of the three age groups (6000, 30,000, and 120,000 yr) reported for this region by the earlier studies of S. K. Gupta and B. S. Amin (1974, Marine Geology 16, 79–83), we could confirm only the 6000-yr group. Instead of a 120,000-yr group, we found a scatter of ages between 118,000 and 176,000 yr. There appears to be no evidence for 30,000-yr-old corals from this region.
On Climatic Analogs in Paleoclimatic Reconstruction
Authors: Bryson Reid A.
Published: December 2004

Many of the problems that have been discussed with regard to the analog approach to paleoclimatic reconstruction may be illustrated by consideration of basic principles and definitions, and the logical consquences thereof. Specific attention is directed toward the definition of the regional macroclimate as the modal microclimate and to a series of axioms: (1) There are various microclimates which depart more or less from the macroclimate in each terrestrial region. (2) Environment and climate change on time scales from near instantaneous to millions of years. (3) Climate is multidimensional (a vector), not a single scalar datum. (4) Biotic assemblage changes in response to environmental (including climatic) changes are expressed primarily in terms of reproductive success. One may conclude from the corollaries to these axioms that perfect analogs cannot be found for any Holocene climate, but that “partial analogs” (“transfer equations”) may still be used if allowance is made for shared variance.
Map of Vegetation during the Last Glacial Maximum in Japan
Authors: Tsukada Matsuo
Published: December 2004

A vegetation map reconstructed for the Japanese Archipelago (based upon pollen data from 28 sites and plant macrofossil data from 33 sites) at the time of last glacial maximum shows that coniferous forests covered extensive areas of the land. Boreal conifer forests (dominated by thePicea jezoensiscomplex,P. glehnii, Abies sachalinensis, A. mariesii, Tsuga diversifolia, andPinuswithLarix gmelinii, though the latter species was confined only to the northern part of northeastern Honshu and Hokkaido) occupied the modern cool-temperature deciduous broadleaf and mid-temperate conifer forest zones, and temperate coniferous forests (mainlyPicea maximowiczii, P. polita, P. bicolor, P. koyamai, Abies firma, A. homolepis, Tsuga sieboldii, andPinus), the present warm-temperate evergreen (laurilignosa) forest zone. Small populations of various broadleaf forest species were scattered in the full-glacial temperate conifer forest mainly along the coastal belt, and the true laurilignosa forest was limited in distribution, occurring only in the paleo-Yaku Peninsula.
Late Pleistocene Paleoclimatology of the Central Equatorial Pacific: A Quantitative Record of Eolian and Carbonate Deposition
Authors: Chuey John M. , Rea David K. , Pisias Nicklas G.
Published: December 2004

Detailed records of δ18O, δ13C, percentage and mass accumulation rate of CaCO3, and eolian percentage, mass accumulation rate, and grainsize generated for core RC11-210 from the equatorial Pacific reveal the timing of paleoclimatic events over the past 950,000 yr. The CaCO3 percentage record shows the standard Pacific correlation of high CaCO3 content with glacial periods, but displays a marked change of character about 490,000 yr ago with older stages showing much less variability. The carbonate mass flux record, however, does not show such a noticeable change. Sedimentation rates vary from about 0.5 to 3.0 cm/1000 yr and, during the past 490,000 yr, sections with enhanced sedimentation rates correspond to periods of high CaCO3 percentage. Eolian mass accumulation rates, an indication of the aridity of the source region, are usually higher during glacial times. Eolian grainsize, an indication of the intensity of atmospheric circulation, generally fluctuates at a higher frequency than the 100,000-yr glacial cycle. The mid-Brunhes climatic event centered at 300,000 yr ago appears as a 50,000-yr interval of low intensity and reduced variability of atmospheric circulation. Furthermore, the nature of this entire record changes then, with the younger portion indicating less variation in wind intensity than the older part of the record. The late Matuyama increase in amplitude of paleoclimatic signals begins 875,000 yr ago in the eolian record, 25,000 yr before the δ18O and CaCO3 percentage amplitude increases about 850,000 yr ago.
California Condor Associated with Spruce-Jack Pine Woodland in the Late Pleistocene of New York
Authors: Steadman David W. , Miller Norton G.
Published: December 2004

A humerus, coracoid, and pedal phalanx of the California Condor,Gymnogyps californianus, were recovered from the Hiscock Site in western New York, in an inorganic stratum containing wood that is 11,000 radiocarbon years old. Associated vertebrates include mastodont, wapiti, and caribou. Pollen and plant macrofossils from the sediments indicate a spruce-jack pine woodland and a local, herb-dominated wetland community. Historic records (all from western North America) and previous late Pleistocene fossils of the California Condor are associated mainly with warm-temperate climates and floras. The New York fossils show that this bird was able to live in a colder climate and in a boreal, coniferous setting at a time when appropriate food (large mammal carrion) was available. The California Condor, which survives only in captivity, has suffered a greater reduction in geographical range than previously suspected. Much of this reduction in range probably occurred ca. 11,000 yr B.P. when the extinction many North American large mammals resulted in severely reduced availability of food for the California Condor and other large scavenging birds.
Palynology of Pleistocene Travertines from the Arava Valley, Israel
Authors: Weinstein-Evron Mina
Published: December 2004

Pollen samples from the Arava travertines, dated to oxygen isotope stages 5 and 7, show relatively high arboreal pollen levels. These spectra are probably a result of an expansion of the Mediterranean maquis in Transjordan, which indicates periods of wetter climatic conditions. These periods probably represent humid fluctuations within stages 5 and 7.
Climatic Implications of Alternating Clay and Carbonate Formation in Semiarid Soils of South-Central Montana
Authors: Reheis Marith C.
Published: December 2004

Evidence for climatic change is found in petrographic thin sections from soils formed on glaciofluvial deposits of Rock Creek and the lower Clarks Fork, Montana. These soils, presently in a semiarid climate, range from late Pliocene to Holocene in age, and have undergone periodic fluctuations in soil moisture caused by climatic changes. In the lower parts of soil B horizons, accretion of illuvial layers of clay (argillans) occurs mainly during wet (glacial) climatic periods, whereas carbonate precipitates mainly during dry (interglacial) climatic periods. Thin-section studies of the argillan and carbonate layers show that: (1) post-Pinedale soils that have formed only in the present interglacial climate contain areas of secondary carbonate unrelated to argillans, (2) soils formed on outwash of successively older glaciations contain proportionately more alternating layers of argillans and carbonate, and (3) the maximum number and sequence of layers in a soil correspond to the number of local cycles of glacial-outwash deposition and subsequent stream incision that followed the beginning of soil formation. These cycles are inferred to correspond to local glacial-interglacial fluctuations. The correspondence between the microscopic record and the glacial-outwash record for Rock Creek suggests that some of the climatic changes seen in the marine oxygen-isotope record did not strongly affect the study area.
Paleohydrological Implications of Holocene Peatland Development in Northern Michigan
Authors: Miller Norton G. , Futyma Richard P.
Published: December 2004

Sediment, pollen, and plant macrofossil stratigraphies from two small oligotrophic Chamaedaphne-Sphagnum peatlands provide data about local hydrologic changes in northern Michigan during the Holocene. Gleason Bog started about 8000 yr B.P. as a shallow pond that supported rich fen vegetation. After it was partly filled with peat and sand (about 4000 yr B.P.), the vegetation changed to oligotrophic bog. At Gates Bog paludification starting about 3800 yr B.P. caused peat accumulation over sand without an initial pond phase. The onset of peat accumulation at both sites is attributed to a rise in the water table resulting from the onset of cool and moist late Holocene climates. The water table of Gleason Bog is linked to the water level of adjacent Douglas Lake, which may have undergone a simultaneous rise. The results emphasize the individuality of hydrological conditions and hydroseral development in northern Michigan peatlands.
Stratigraphy and Magnetic Polarity of the High Terrace Remnants in the Upper Ohio and Monongahela Rivers in West Virginia, Pennsylvania, and Ohio
Authors: Jacobson Robert B. , Elston Donald P. , Heaton John W.
Published: December 2004

A synthesis of previous work and new data on the stratigraphy of high terraces of the Ohio and Monongahela Rivers upstream from Parkersburg, West Virginia, indicates a correspondence between terrace histories in the ancient Teays and Pittsburgh drainage basins. Four terraces are identified in each. Sediments of the lower three alluvial and slackwater terraces, correlated with Illinoian, early Wisconsin, and late Wisconsin glacial deposits, have been traced along the modern Ohio River through the former divide between the Teays and Pittsburgh basins. Sediments in the fourth terrace, the highest well-defined terrace in each basin, were deposited in two ice-dammed lakes, separated by a divide near New Martinsville, West Virginia. Some deposits of the highest slackwater terrace in both the Teays and Pittsburgh basins have reversed remanent magnetic polarity. This, and the stratigraphic succession in the two basins, suggests that both were ponded during the same glaciation. Reversed polarity in these terrace sediments restricts the age of the first ice-damming event for which stratigraphic evidence is well-preserved to a pre-Illinoian, early Pleistocene glaciation prior to 788,000 yr ago. In contrast, slackwater sediments in the Monongahela River valley, upstream from an outwash gravel dam at the Allegheny-Monongahela confluence, have normal remanent magnetic polarity, corroborating correlation with an Illinoian ponding event.
Relationship Between Climate and Vegetation and the Stable Carbon Isotope Chemistry of Soils in the Eastern Mojave Desert, Nevada
Authors: Amundson Ronald G. , Chadwick Oliver A. , Sowers Janet M. , Doner Harvey E.
Published: December 2004

The relationship between the stable C-isotope composition of the soil environment and modern climate and vegetation was determined empirically along a present-day climatic transect in the eastern Mojave Desert. The δ13C of the soil CO2 and carbonates decreased with increasing elevation and plant density, even though plant assemblages at all elevations were isotopically similar. Several factors, including differences in the ratios of pedogenic of limestone calcite and differences in past vegetation, were considered as explanations of this trend, However, it appears that in the sparsely vegetated Mojave Desert, the δ13C of pedogenic carbonate is controlled by differences in plant density and biological activity. This relationship may provide a tool for assessing past vegetational densities, as long as the vegetation is isotopically homogeneous.
Revised Magnetostratigraphies Confirm Low Sedimentation Rates in Arctic Ocean Cores
Authors: Witte William K. , Kent Dennis V.
Published: December 2004

The general lack of an age-diagnostic biostratigraphy in the Neogene sediments of the abyssal Arctic Ocean has emphasized the importance of magnetostratigraphy in providing chronostratigraphic control in these sediments. Sedimentation rates interpreted from early magnetostratigraphic studies of cores taken from the T3 ice island in the western Mendeleev Plain were estimated to be on the order of 1 mm/103 yr; however, recent amino acid epimerization studies of a core from the same area have suggested sedimentation rates of almost 15 mm/103 yr. This controversy has led us to reexamine the paleomagnetism of several of these cores. Our alternating field demagnetization studies indicate that many of these cores have an intense, high coercivity overprint, acquired after the core was opened, that is adequately removed only after treatment at 20 to 70 mT. We have remeasured samples from two cores after demagnetizations up to 80 mT and can confirm the position of the Brunhes/Matuyama boundary originally identified in the cores. In addition, the Jaramillo and Olduvai subchrons are identified. Average sedimentation rates in these two cores are 2–3 mm/103 yr, similar to the original estimates based on reversal stratigraphy, as well as those determined from recent radiocarbon studies, but incompatible with the amino acid-based dates.
Anomalous Radiocarbon Ages from a Holocene Detrital Organic Lens in Alaska and their Implications for Radiocarbon Dating and Paleoenvironmental Reconstructions in the Arctic
Authors: Nelson Robert E. , Carter L. David , Robinson Stephen W.
Published: December 2004

Eleven radiocarbon age determinations clearly show that a lens of Holocene fluvial organic debris on the Alaskan Arctic Coastal Plain contains mostly pre-Holocene organic material. Radio-carbon ages of identified plant macrofossils indicate the material was deposited about 9000 to 9500 yr B.P. Radiocarbon analyses of bulk samples from this deposit, however, range from 13,300 to 30,300 yr B.P. Most of the old organic matter seems to be in the smaller size fractions in the deposit, particularly in the fraction between 0.25 and 0.5 mm, but all size fractions are contaminated. Particular caution must be exercised in submitting bulk samples for radiocarbon dating from areas where conditions favor redeposition of isotopically “dead” carbon.
Late Quaternary Landscape Evolution at Flat Laurel Gap, Blue Ridge Mountains, North Carolina
Authors: Shafer David S.
Published: December 2004

Analysis of colluvial, fluvial, and bog sediments at Flat Laurel Gap (1500 m) in the Blue Ridge Mountains of North Carolina provides a record of late Quaternary landscape evolution. Thermoluminescence (TL) analysis provides the first absolute-age determinations available for presumed periglacial deposits in the southern Appalachian Mountains. The Pleistocene/Holocene transition, dated between 11,900 and 10,100 yr B.P., represents a period of climatic amelioration and a change from colluvial to alluvial processes. A TL date of 7400 ± 1000 yr B.P. for matrix within a block-stream indicates possible early Holocene reworking of Pleistocene periglacial colluvium. Organic sediment deposition in a bog that began about 3400 yr B.P. increased in rate from 0.02 to 0.09 cm/yr with the onset of logging and land clearance about 1880 A.D.
Structural Position of the Pleistocene Gesher Benot Ya'aqov Site in the Dead Sea Rift Zone
Authors: Goren-Inbar N. , Belitzky S.
Published: December 2004

Newly discovered outcrops of the middle Pleistocene Benot Ya'aqov Formation are strongly disturbed due to recent tectonic activity along the Dead Sea Rift. The lacustrine-fluviatile sediments of this formation comprise the littoral facies of a paleo-lake that occupied the adjacent Hula Basin. Acheulian artifacts, found embedded in the formation, have typical African characteristics. The geographical position of the site (the northern extension of the East African Red Sea Rift System) is important for understanding hominid diffusion from Africa to Eurasia.
Climate and Habitat Reconstruction Using Stable Carbon and Nitrogen Isotope Ratios of Collagen in Prehistoric Herbivore Teeth from Kenya
Authors: Ambrose Stanley H. , DeNiro Michael J.
Published: December 2004

Stable carbon and nitrogen isotope ratios have been determined for tooth collagen of 27 prehistoric herbivores from a rock shelter in the central Rift Valley of Kenya. Collagen samples whose isotope ratios were not altered by diagenesis were identified using several analytical methods. During the later Holocene, when the climate was as dry or drier than at present, the isotopic compositions of individual animals are similar to those of modern individuals of the same species. During the earlier Holocene, when the climate was wetter than at present, the δ15N and δ13C values are lower than those for their modern counterparts. When diagenetic factors can be discounted and adequate modern comparative data are available, stable isotope analysis of herbivore teeth and bones can be used to evaluate prehistoric climate and habitat conditions.
Ages of Travertine Deposits in Eastern Grand Canyon National Park, Arizona
Authors: Szabo Barney J.
Published: December 2004

Travertine deposits in eastern Grand Canyon National Park, Arizona, are inferred to have formed under conditions of effective wetness that were greater than present. Uranium-series dating of 17 samples indicates that the deposits formed at about 15,000, 71,000, 111,000, 171,000, and 338,000 yr B.P. Intervals of travertine deposition are essentially contemporaneous with dated high paleolake levels, montane glacial maxima, and high paleowater-table levels from several Great Basin localities.
Stratigraphic and Tectonic Implications of Uranium-Series-Dated Coral Reefs from Uplifted Red Sea Islands
Authors: Hoang Chi Trach , Taviani Marco
Published: December 2004

Corals from raised reef terraces on two islands (Zabargad and Northern Brother), considered to have been tectonically uplifted in connection with the Red Sea rifting, were dated with the U-series method. At Zabargad, there are at least three systems of raised coral reefs. The oldest terrace (>290,000–300,000 yr B.P.) is found at +10 to +15 m. A 200,000 yr B.P. high-sea stand is recorded by a terrace relict at +17 m on peridotite bedrock; the youngest system (125,000–138,000 yr B.P.) is very well represented around the island, with terraces at about +6 to +8 m. Corals from Northern Brother yield ages of 132,000–135,000 and 204,000 yr B.P. suggesting the existence of two systems of interglacial raised reefs. Both islands appear to have been tectonically quite stable since at least 125,000 yr B.P.
Mid-Wisconsinan Vertebrates and their Environment from January Cave, Alberta, Canada
Authors: Burns James A.
Published: December 2004

January Cave, in the Rocky Mountains of southwestern Alberta, has yielded vertebrate remains from a coprocenosis of mid-Wisconsinan-age. Taphonomic analysis indicates accumulation by raptors, mostly owls, and mammalian carnivores. The vertebrate record, together with pollen analysis, indicates that cool, dry conditions prevailed in an extensive tundra-like environment, with prairie elements in the valleys below. Thirty-four mammalian taxa have been recovered from January Cave. Today, some of these species (e.g.,Lemmus sibiricusandDicrostonyx torquatus) do not coexist with others (e.g.,Cynomyssp.,Mustela nigripes, Vulpes velox, andLagurus curtatus). Therefore, the January Cave local fauna represents a “nonanalog” mammalian community characteristic of the late Pleistocene. It suggests that the region enjoyed an equable climate, with reduced climatic extremes but still cool, further supporting a mid-Wisconsinan age estimate for the fauna. It is the first major, small vertebrate fauna of its age to be reported from Alberta.
Probing the active site of homoserine trans‐succinylase
Authors: Rosen Ran , Becher Dörte , Büttner Knut , Biran Dvora , Hecker Michael , Ron Eliora Z.
Published: December 2004

Homoserine trans‐succinylase is the first enzyme in methionine biosynthesis of Escherichia coli and catalyzes the activation of homoserine via a succinylation reaction. The in vivo activity of this enzyme is subject to tight regulation by several mechanisms, including repression and activation of gene expression, feedback inhibition, temperature regulation and proteolysis. This complex regulation reflects the key role of this enzyme in bacterial metabolism. Here, we demonstrate – using proteomics and high‐resolution mass spectrometry – that succinyl is covalently bound to one of the two adjacent lysine residues at positions 45 and 46. Replacing these lysine residues by alanine abolished the enzymatic activity. These findings position the lysine residues, one of which is conserved, at the active site.
Militarinone A induces differentiation in PC12 cells via MAP and Akt kinase signal transduction pathways
Authors: Riese Ulrike , Ziegler Elke , Hamburger Matthias
Published: December 2004

The fungal metabolite militarinone A (MILI A) promotes neurite outgrowth in PC12 cells. This study was conducted to investigate the signaling pathways involved in the cellular differentiation processes induced by the compound, with a focus on cascades implicated with nerve growth factor (NGF)‐mediated neuritogenesis. MILI A possessed pronounced amphiphilic properties. The compound rapidly accumulated in the cell membrane and was slowly released into the cytoplasma. In primed PC12 cells, an early activation of protein kinase B (Akt), representing a downstream target of phosphoinositol 3 (PI3) kinase, and a delayed phosphorylation of extracellular signal‐regulated kinases 1 and 2 (ERK1/2), and of transcription factor cAMP responsive element binding protein (CREB) was found. The NGF‐dependent activation of c‐Jun amino terminal kinase (SAPK/JNK1) was potentiated. Morphological differentiation of cells and the phosphorylation of specific signal molecules were blocked by the MAP kinase (MEK1) inhibitor PD098059, the PI3‐kinase (PI3K) inhibitor wortmannin and the adenylyl cyclase inhibitor 9‐cyclopentyladenine.
Instructor use on online language learning resources: A survey of socio-institutional and motivational factors
Authors: REINHARDT JONATHON , NELSON BARBARA K.
Published: December 2004

In response to the need for research on the contextualized use of CALL resources, the authors conducted a
survey on instructor use of a popular online Spanish language learning resource to provide insight into how foreign language
instructors’ use of online resources are influenced by socio-institutional factors and instructor motivational factors
such as personal background and teaching philosophy. From the 118 survey participants, the authors used quantitative techniques
to choose three case studies that represented the diversity of respondents who use the resource in their teaching. They present
overall trends and qualitative profiles of the three instructors with the intent to gain an overall understanding of the nature
of how the resource is used, not only to provide direction for future quantitative research, but also to illustrate the utility of
qualitative research in providing such understanding. Upon analysis of the case studies, the authors conclude that the actual
use of a CALL resource may be far from the ideal use the designer intended, and that the use of CALL resources is highly contingent
on the sociocultural context of the implementation of the resource. Instructor comments seem to point not towards the physical
CALL infrastructure of an instructor’s workplace as a determining factor of resource use, but towards the CALL culture and
collegiality of the environment. Most revealing of the nature of an instructor’s use of a resource seems to be the
congruence of site features with the instructor’s teaching philosophy, itself the product of a variety of factors.
CALL and the development of learner autonomy: Towards an activity-theoretical perspective
Authors: BLIN FRANÇOISE
Published: December 2004

While the concepts and principles associated with learner autonomy underpin a broad range of CALL
applications and research projects, current debates and research paradigms in CALL do not provide adequate tools and
models to investigate in depth the relationship between CALL and the development of learner autonomy. This paper explores the
potential of cultural-historical activity theory to study this relationship. Starting from the complex and multidimensional
nature of learner autonomy, it highlights some of the weaknesses in the CALL literature addressing some aspects of this
relationship. Following a presentation of the main tenets of cultural-historical activity theory (CHAT), including the notion of
contradiction which is at the core of CHAT, it then seeks to demonstrate how activity theory can assist us in rethinking our
understanding of learner autonomy in the context of technology-rich language learning environments and in formulating suitable
criteria and questions, which can guide judgemental and empirical analyses. The paper concludes by illustrating some of the
principles explored through examples drawn from an activity-theoretical judgemental analysis of a French module delivered to
first year students in Dublin City University.
Preparing the new generation of CALL researchers and practitioners: What nine months in an MA program
can (or cannot) do
Authors: HEGELHEIMER VOLKER , REPPERT KETTY , BROBERG MEGAN , DAISY BRENDA , GRGUROVIC MAJA , MIDDLEBROOKS KATY , LIU SAMMI
Published: December 2004

As more and more teacher preparation programs realize the need to include courses that deal with
computer-assisted language learning, a crucial decision as to what is taught needs to be made, taking into consideration the
various post-graduation goals ranging from teacher or teacher-trainer to researcher. Thus, the question of whether to go beyond
teaching the potential uses of the computer and the Internet and to delve into how to create relevant computer-based tasks using
the WWW and to train teachers in the use of advanced web page development techniques, including Flash, web-enabled databases, and
the interactive possibilities of the WWW needs to be addressed. This paper tackles these issues and illustrates a sample approach
in dealing with the grooming of the new generation of CALL researchers and practitioners. What can be accomplished during the
first year of an MATESL program that highlights the importance of technology is explored through a reflective questionnaire,
a computer capabilities matrix, and an analysis of web-based course projects. Nine first-year M.A. students participated in the
study, which revealed that despite widely differing initial computer and Internet expertise among these future teachers and
researchers, their knowledge of creating and using web-based materials increased significantly, culminating in a project in
which the skills acquired throughout the semester were successfully integrated.
A principle-based approach to teaching grammar on the web
Authors: BEAUDOIN MARTIN
Published: December 2004

The advantages of computer-assisted grammar teaching and more recently, web-based grammar teaching,
include the possibility, for the instructor, of devoting class time to teaching communication skills, and the capacity of
individualizing the course work. Several websites have been created for these very reasons. However, most of these sites include
only a small portion of the grammar and very few are based on educational principles. This paper will summarize what should be
the guiding principles in the design of this type of website, most of which involve instructional design and the need for structure
and adaptability to different learning styles. It should also be noted that there are design principles specific to grammar
teaching, such as the distinction between exploratory and pre-established modes, and the scaffolding of concepts. The application
of these principles will be illustrated through the presentation of a web site.
Evaluation of CALL: Initial vocabulary learning
Authors: ALLUM PAUL
Published: December 2004

Vocabulary learning theory suggests that productive recall should strengthen learning of new vocabulary
items (Nation, 2001). CALL can provide both the opportunities for productive recall and the feedback to motivate repeated efforts
to reproduce new items. The latter capability appears to give CALL some advantages over paper-based exercises, in particular when
such learning is done out of class time without immediate teacher feedback. Three experiments are reported. In the first two, a
comparison is made of CALL exercises that encourage productive recall with those that encourage passive recall. Initially productive
recall appears to give greater learning gains, supporting theory. Over time, the results are comparable. Both groups make substantial
gains. Observation suggests that students apply their own strategies to enhance recall, to some extent independently of the exercise
type. The advantages and disadvantages of incorporating productive recall into the design of CALL exercises need to be considered
together with those of students applying their own strategies to enhance recall. Based on the outcome of this assessment, a
sequence of exercises to introduce new vocabulary is designed that encourages passive and active recall as well as other
strategies thought to help initial vocabulary learning. In the third experiment, these exercises are delivered over the Web
for a whole semester as preparatory materials for in-class work. Outcomes are reported in terms of learning gains but particular
attention is paid to evaluating maintenance of student motivation. It is suggested that CALL is an effective way to introduce
new vocabulary, that such effectiveness is enhanced by designing exercises based on theory, and that it works well for
sustained periods, even in circumstances where student motivation is not necessarily high, when there is close integration
with classroom work.
Measurement of peroxycarboxylic nitric anhydrides (PANs) during the ITCT 2K2 aircraft intensive experiment
Authors: Roberts James M. , Flocke Frank , Chen Gao , de Gouw Joost , Holloway John S. , Hübler Gerd , Neuman J. Andrew , Nicks Dennis K. , Nowak John B. , Parrish David D. , Ryerson Thomas B. , Sueper Donna T. , Warneke Carsten , Fehsenfeld Fred C.
Published: December 2004

Measurements of peroxycarboxylic nitric anhydrides (PANs), peroxyacetic nitric anhydride (CH3C(O)OONO2; PAN), and peroxypropionic nitric anhydride (CH3CH2C(O)OONO2; PPN) were made in the spring of 2002, off the west coast of North America, as part of the Intercontinental Transport and Chemical Transformation 2002 (ITCT 2K2) project. Long‐range transport of Asian emissions was observed in which PAN and PPN mixing ratios were as high as 650 pptv and 90 pptv, respectively. Moreover, these two species constituted as much as 80% of the odd nitrogen (NOy) in those air masses, and median PAN/NOy was more than 60% at altitudes of 4 km and above. Systematic differences in the ratio of PPN to PAN were observed in air masses that had been impacted by Asian urban emissions relative to those impacted by biomass burning. Mixing ratios of PAN and PPN were also elevated in the marine boundary layer close to the west coast of California, possibly because of photochemical production driven by maritime NOx emissions.
Feeding ecology of little terns Sterna albifrons sinensis in south-eastern Australia and the effects of pilchard mass mortality on breeding success and population size
Authors: Taylor Iain R. , Roe Emma L.
Published: December 2004

Little terns Sterna albifrons sinensis breeding on Rigby Island, Gippsland Lakes in south-east Australia fed their chicks entirely on juvenile fish of the families Clupeidae, Engraulidae, Pomatomidae and Carangidae, including pilchard Sardinops neopilchardus, southern anchovy Engraulis australis and blue sprat Spratelloides robustus. The entrance channel to the Lakes was an important feeding site. Numbers feeding there increased on the flood tide and decreased on the ebb tide. Their dive rates followed the same pattern, suggesting they depended on shoals of juvenile fish entering the estuary during high tide. The number feeding varied from day to day, and dive rates were positively correlated with numbers, suggesting that the abundance of juvenile fish entering the channel also varied from day to day. There was no evidence that breeding success or number of breeding pairs were adversely affected by the 1995 mass mortalities of pilchard in the area. However, breeding success was reduced significantly in 1999 and 2000 following the 1998/1999 pilchard mortality. The 1995 mortality affected mainly larger size classes of pilchard, whereas the 1998/1999 mortality also affected younger age classes. This difference may explain why little terns seemed only to be adversely affected by the second mortality event.
Strand invasion promoted by recombination protein β of coliphage λ
Authors: Rybalchenko Nataliya , Golub Efim I. , Bi Baoyuan , Radding Charles M.
Published: December 2004

Studies of phage λ
in vivo
have indicated that its own recombination enzymes, β protein and λ exonuclease, are capable of catalyzing two dissimilar pathways of homologous recombination that are widely distributed in nature: single-strand annealing and strand invasion. The former is an enzymatic splicing of overlapping ends of broken homologous DNA molecules, whereas the latter is characterized by the formation of a three-stranded synaptic intermediate and subsequent strand exchange. Previous studies
in vitro
have shown that β protein has annealing activity, and that λ exonuclease, acting on branched substrates, can produce a perfect splice that requires only ligation for completion. The present study shows that β protein can initiate strand invasion
in vitro
, as evidenced both by the formation of displacement loops (D-loops) in superhelical DNA and by strand exchange between colinear single-stranded and double-stranded molecules. Thus, β protein can catalyze steps that are central to both strand annealing and strand invasion pathways of recombination. These observations add β protein to a set of diverse proteins that appear to promote recognition of homology by a unitary mechanism governed by the intrinsic dynamic properties of base pairs in DNA.
Curriculum innovation within an evaluative state: issues of risk and regulation
Authors: Halpin David , Dickson Marny , Power Sally , Whitty Geoff , Gewirtz Sharon
Published: December 2004

The English EAZ experience illustrates the difficulties of developing an innovative, responsive and inclusive curriculum within an evaluative state characterized by high stakes testing. Consequently, while government exhortations to ‘raise standards’, ‘innovate’ and ‘promote social inclusion’ clearly serve an important rhetorical function, they may underestimate the challenges involved and overestimate the capacity of schools within disadvantaged areas to ‘make a difference’.
From performance management to capacity‐building: an escape from the cul de sac?
Authors: Storey Anne
Published: December 2004

This article examines the many critiques of educational policies concerning the National Curriculum and the standards and testing regimes for pupils and teachers associated with it. It goes on to suggest that there is a danger of educational researchers and policy‐makers arguing themselves into a cul de sac where an unproductive stand‐off may prevail. It is argued that a more productive way forward is to be found in a focus on the ‘capacity‐building’ of teachers using formative assessment and double‐loop learning as the basis for action. This will present a challenge for teachers as well as for policy‐makers.
The National Literacy Strategy and setting: an investigation in one school
Authors: Wall Kate
Published: December 2004

This article investigates the policy of setting that is commonly being seen as an organizational tool for effective delivery of the National Literacy Strategy (NLS). It is suggested that teachers are finding the increased amount of whole‐class teaching to a diverse range of abilities, as prescribed by the NLS, problematic. This case‐study researches both teachers' and children's perspectives on the Literacy Hour as taught in mixed‐ability classes and in sets. Reflective commentaries and pupil questionnaires were used to collect data over two years. The results indicate a complex range of issues, both pedagogical and organizational, which need be considered before setting can be promoted as a strategy for literacy delivery. I conclude that there is a need for urgent research into the effectiveness of setting as a means of teaching the Literacy Hour.
ICT resources in the teaching of mathematics: between computer and school technologies. A case‐study
Authors: Bosco Alejandra
Published: December 2004

This article is based on a research project called ‘Information and communications technology (ICT) resources in school organizational and symbolic technology: a case‐study’ which was carried out in a primary school in Barcelona, Spain. The research looked at various interactions that took place between the computer as a teaching tool, the teachers' teaching practices and the children's learning. The observations of these interactions focus on both the process of integration of the computer in school and the way in which this medium affects and is affected by school teaching practices, and the learning process of the children partaking in those practices.
ADAM12 and α9β1Integrin Are Instrumental in Human Myogenic Cell Differentiation
Authors: Lafuste Peggy , Sonnet Corinne , Chazaud Bénédicte , Dreyfus Patrick A. , Gherardi Romain K. , Wewer Ulla M. , Authier François-Jérôme
Published: December 2004

Knowledge on molecular systems involved in myogenic precursor cell (mpc) fusion into myotubes is fragmentary. Previous studies have implicated the a disintegrin and metalloproteinase (ADAM) family in most mammalian cell fusion processes. ADAM12 is likely involved in fusion of murine mpc and human rhabdomyosarcoma cells, but it requires yet unknown molecular partners to launch myogenic cell fusion. ADAM12 was shown able to mediate cell-to-cell attachment through binding α9β1integrin. We report that normal human mpc express both ADAM12 and α9β1integrin during their differentiation. Expression of α9parallels that of ADAM12 and culminates at time of fusion. α9and ADAM12 coimmunoprecipitate and participate to mpc adhesion. Inhibition of ADAM12/α9β1integrin interplay, by either ADAM12 antisense oligonucleotides or blocking antibody to α9β1, inhibited overall mpc fusion by 47–48%, with combination of both strategies increasing inhibition up to 62%. By contrast with blockade of vascular cell adhesion molecule-1/α4β1, which also reduced fusion, exposure to ADAM12 antisense oligonucleotides or anti-α9β1antibody did not induce detachment of mpc from extracellular matrix, suggesting specific involvement of ADAM12–α9β1interaction in the fusion process. Evaluation of the fusion rate with regard to the size of myotubes showed that both ADAM12 antisense oligonucleotides and α9β1blockade inhibited more importantly formation of large (≥5 nuclei) myotubes than that of small (2–4 nuclei) myotubes. We conclude that both ADAM12 and α9β1integrin are expressed during postnatal human myogenic differentiation and that their interaction is mainly operative in nascent myotube growth.
Phosphorylation-regulated Nucleocytoplasmic Trafficking of Internalized Fibroblast Growth Factor-1
Authors: Więdłocha Antoni , Nilsen Trine , Wesche Jørgen , Sørensen Vigdis , Małecki Jędrzej , Marcinkowska Ewa , Olsnes Sjur
Published: December 2004

Fibroblast growth factor-1 (FGF-1), which stimulates cell growth, differentiation, and migration, is capable of crossing cellular membranes to reach the cytosol and the nucleus in cells containing specific FGF receptors. The cell entry process can be monitored by phosphorylation of the translocated FGF-1. We present evidence that phosphorylation of FGF-1 occurs in the nucleus by protein kinase C (PKC)δ. The phosphorylated FGF-1 is subsequently exported to the cytosol. A mutant growth factor where serine at the phosphorylation site is exchanged with glutamic acid, to mimic phosphorylated FGF-1, is constitutively transported to the cytosol, whereas a mutant containing alanine at this site remains in the nucleus. The export can be blocked by leptomycin B, indicating active and receptor-mediated nuclear export of FGF-1. Thapsigargin, but not leptomycin B, prevents the appearance of active PKCδ in the nucleus, and FGF-1 is in this case phosphorylated in the cytosol. Leptomycin B increases the amount of phosphorylated FGF-1 in the cells by preventing dephosphorylation of the growth factor, which seems to occur more rapidly in the cytoplasm than in the nucleus. The nucleocytoplasmic trafficking of the phosphorylated growth factor is likely to play a role in the activity of internalized FGF-1.