bluuebunny/crossref_metadata_2025 huggingface dataset:
Stratigraphy, sedimentology and palaeoecology of the dinosaur-bearing Kundur section (Zeya-Bureya Basin, Amur Region, Far Eastern Russia)
Authors: VAN ITTERBEECK J. , BOLOTSKY Y. , BULTYNCK P. , GODEFROIT P.
Published: October 2005

Since 1990, the Kundur locality (Amur Region, Far Eastern Russia) has yielded a rich dinosaur fauna. The main fossil site occurs along a road section with a nearly continuous exposure of continental sediments of the Kundur Formation and the Tsagayan Group (Udurchukan and Bureya formations). The sedimentary environment of the Kundur Formation evolves from lacustrine to wetland settings. The succession of megafloras discovered in this formation confirms the sedimentological data. The Tsagayan Group beds were deposited in an alluvial environment of the ‘gravel-meandering’ type. The dinosaur fossils are restricted to the Udurchukan Formation. Scarce and eroded bones can be found within channel deposits, whereas abundant and well-preserved specimens, including sub-complete skeletons, have been discovered in diamicts. These massive, unsorted strata represent the deposits of ancient sediment gravity flows that originated from the uplifted areas at the borders of the Zeya-Bureya Basin. These gravity flows assured the concentration of dinosaur bones and carcasses as well as their quick burial. Such taphonomic conditions allowed the preservation of sub-complete hadrosaurid skeletons unearthed at the Kundur site. Palaeobotanical data indicate a subtropical climate during the deposition of the Kundur and Udurchukan formations. Several elements in the composition of the Kundur vertebrate fauna suggest a strong influence of the North American late Cretaceous vertebrate communities: the abundance of corythosaur-like lambeosaurines, the probable presence of a nodosaurid dinosaur and of a eucosmodontid or microcosmodontid multituberculate. A late Maastrichtian age is tentatively proposed for the dinosaur-bearing sediments in Amur Region, by comparison with the information collected in the Western Interior Basin of North America. As it is also observed in the latter area, important floristic changes (diminution of angiosperm pollens and predominance of modern families) and the disappearance of dinosaurs mark the end of the Maastrichtian age in the Amur Region. Late Maastrichtian dinosaur localities from Amur Region are dominated by lambeosaurines, whereas these dinosaurs apparently disappeared from western North America long before the iridium horizon that defines the K/P boundary. This local disappearance is therefore probably due to ecological factors rather than indicating a gradual extinction of the dinosaurs long before the K/P boundary.
Microsatellite analysis of pooledSchistosoma mansoniDNA: an approach for studies of parasite populations
Authors: SILVA L. K. , LIU S. , BLANTON R. E.
Published: October 2005

Human parasites are often distributed in metapopulations, which makes random sampling for genetic epidemiology difficult. The typical approach to samplingSchistosoma mansoniinvolves laboratory passage to obtain individual worms with small sample size and selection bias as a consequence. By contrast, the naturally pooled samples from egg output in stool or urine directly represent the genetic composition of current populations. To test whether pooled samples could be used to estimate population allele frequencies, DNA from individual cloned parasites was pooled and amplified by PCR for 7 microsatellites. By polyacrylamide gel analysis, the relative band intensities of the products from the major alleles in the pooled samples differed by 0–6% from the summed intensities of the individual clones (mean=2·1%±2·1%S.D.). The number of PCR cycles (25–40) did not influence the accuracy of the estimate. Varying the frequency of 1 allele in pooled samples from 32 to 69% likewise did not affect accuracy. Allele frequency estimates from aggregate samples such as eggs will be a better foundation for studies of parasite population dynamics as well as the basis for large-scale association studies of host and parasite characteristics.
The impact of the Catholic Jubilee in 2000 on infectious diseases. A case-control study of giardiasis, Rome, Italy 2000–2001
Authors: FAUSTINI A. , MARINACCI C. , FABRIZI E. , MARANGI M. , RECCHIA O. , PICA R. , GIUSTINI F. , LA MARCA A. , NACCI A. , PANICHI G. , PERUCCI C. A.
Published: October 2005

Mass gatherings are believed to increase the transmission of infectious diseases although surveillance systems have shown a low impact. The Catholic Jubilee was held in Rome, Italy in 2000. We conducted a case-control study to analyse the risk factors of giardiasis among residents. All diseases reported to the laboratory surveillance system from January 2000 to May 2001 were compared with hospital controls concurrently selected in the same season as cases and frequency-matched for age and birth country. Fifty-two cases (44·1%) and 72 controls were enrolled. In the multivariable analysis factors associated with giardiasis among adults were: travelling abroad (OR 24·2, P>0·01), exposure to surface water (OR 4·80, P=0·05), high educational level (OR 3·8, P=0·03). Having a maid from a high-prevalence country was independently associated (OR 2·3) although not statistically significant. This is the only exposure that changed during the Jubilee.
It's the Thought that Counts
Authors: HOWARD-SNYDER FRANCES
Published: October 2005

Agnes's brakes fail. Should she continue straight into the busy intersection or should she swerve into the field? Add to the story, what Agnes does not and cannot know, that continuing into the intersection will cause no harm, whereas swerving into the apparently empty field will cause a death. I evaluate arguments for the claim that she should enter the intersection, i.e. for objectivism about right and wrong; and arguments for the claim that she should swerve, i.e. for subjectivism about right and wrong, and conclude that subjectivism is more plausible. I also consider the view that ‘ought’ and ‘wrong’ are systematically ambiguous, that she subjectively ought to swerve and that she objectively ought to enter the intersection. I argue that most versions of this suggestion are unworkable, and that even the best version is less plausible than pure subjectivism.
Virtue Consequentialism
Authors: BRADLEY BEN
Published: October 2005

Virtue consequentialism has been held by many prominent philosophers, but has never been properly formulated. I criticize Julia Driver's formulation of virtue consequentialism and offer an alternative. I maintain that according to the best version of virtue consequentialism, attributions of virtue are really disguised comparisons between two character traits, and the consequences of a trait in non-actual circumstances may affect its actual status as a virtue or vice. Such a view best enables the consequentialist to account for moral luck, unexemplified virtues, and virtues and vices involving the prevention of goodness and badness.
Equality and Priority
Authors: PETERSON MARTIN , HANSSON SVEN OVE
Published: October 2005

This article argues that, contrary to the received view, prioritarianism and egalitarianism are not jointly incompatible theories in normative ethics. By introducing a distinction between weighing and aggregating, the authors show that the seemingly conflicting intuitions underlying prioritarianism and egalitarianism are consistent. The upshot is a combined position, equality-prioritarianism, which takes both prioritarian and egalitarian considerations into account in a technically precise manner. On this view, the moral value of a distribution of well-being is a product of two factors: the sum of all individuals' priority-adjusted well-being, and a measure of the equality of the distribution in question. Some implications of equality-prioritarianism are considered.
Blame, Respect and Recognition: A Reply to Theo van Willigenburg
Authors: SKORUPSKI JOHN
Published: October 2005

In an article in Utilitas Theo van Willigenburg has argued that moral valuation is distinguished from other forms of valuation by the Kantian concept of respect. He criticizes, from that standpoint, an account I put forward, which builds on the connections between moral wrongdoing, blame and withdrawal of recognition. I examine the difference between these two approaches and defend my own.
Vortex pinning in super-conductivity as a rate-independent process
Authors: SCHMID FLORIAN , MIELKE ALEXANDER
Published: October 2005

For superconductors of type II the phenomenon of vortex pinning plays an important role in technological applications. Several models have been proposed for this effect (Kim et al., 1963; Bean, 1964; Bossavit, 1994). In Du et al. (1999) and Prigozhin (1996), some of these models are analyzed. In this work we want to contribute to the analysis for the two-dimensional, rate-independent model proposed in Chapman (2000), which has the special feature that vortex movement and creation is an activated process occurring only when a threshold value of the magnetic field is reached. For analytical studies of related rate-dependent models we refer to Chapman et al. (1996), Schätzle & Styles (1999) and Elliott & Styles (2000).
Carbon isotope of bulk organic matter: A proxy for precipitation in the arid and semiarid central East Asia
Authors: Lee Xinqing , Feng Zhaodong , Guo Lanlan , Wang Lixia , Jin Liya , Huang Yongsong , Chopping Mark , Huang Daikuan , Jiang Wei , Jiang Qian , Cheng Hongguang
Published: October 2005

Carbon isotope composition (δ13C) of bulk organic matter in soil and lake sediment sequences has been widely used to infer past climate changes. The specific climatic representation of the isotopic signature, however, lacks for examination. With excellent gradients of temperature and precipitation, as well as the gradients of vegetation zone, central East Asia provides an ideal background for developing the relationship between the δ13C and the climatic parameters. Analysis of surface soil organic matter from a transect that crosses the various climatic and vegetation zones reveals a significant linear correlation between δ13C and the mean precipitation from May to September yet a very poor relationship between δ13C and temperature. The close correlation between the δ13C and the precipitation is also corroborated by measurement of some C3 shrubs along the transect. Precipitation in the arid central East Asia is a key factor controlling the relative competition or the distribution of plant species with different photosynthetic pathways, thus the carbon isotope signature in the bulk organic matter. Its variation, therefore, can be recovered by measurement of δ13C in soils or lake sediment sequences with terrestrial organic matters.
Burial of terrestrial organic matter in marine sediments: A re‐assessment
Authors: Burdige David J.
Published: October 2005

Calculations based on recent observations indicate that approximately one third of the organic matter presently being buried in marine sediments may be of terrestrial origin, with the majority of this terrestrial organic matter (TOM) burial occurring in muddy, deltaic sediments. These calculations further suggest that the remineralization of terrestrial organic matter in the oceans is also much less efficient than that of marine organic matter. These two underappreciated observations have important implications in terms of our understanding of the controls on the global carbon cycle. From a paleoceanographic perspective, the results presented here also suggest that changes in TOM burial on glacial‐interglacial timescales have the potential to impact the global carbon cycle (i.e., atmospheric CO2 levels).
Generation of internal waves in the deep ocean by tides
Authors: Nycander J.
Published: October 2005

A direct computation of the tidal generation of internal waves over the global ocean is presented. It is based on linear wave theory and high‐resolution data for the bottom topography. The geographical distribution of the energy flux from tides to internal waves is determined with a spatial resolution of a few kilometers. The total flux over the area with a depth greater than 500 m is found to be 1.2 TW. The greatest uncertainties of the computation are due to unresolved topography and to nonlinear effects caused by supercritical bottom slope.
Seasonal variation in total organic carbon in the northeast Atlantic in 2000–2001
Authors: Sohrin Rumi , Sempéré Richard
Published: October 2005

Total organic carbon (TOC) was measured in the midlatitudes of the northeast Atlantic in 2000–2001 during the Programme Océan Multidisciplinaire Méso Echelle (POMME). In spring, mixed layer depth (MLD) was positively correlated with the north latitude, while the surface TOC and chlorophyll‐a (Chl a) were negatively correlated with it. It indicates the northward propagation of TOC accumulation along the onset of spring bloom, which was triggered by shoaling of MLD from the south. Surface TOC was highest in summer, though surface Chl a was lowest. Surface TOC was significantly correlated with surface Chl a during winter and spring but not during summer or fall, indicating the minor influence of total phytoplankton biomass on surface TOC distribution in the oligotrophic season. High surface TOC in summer and fall was related with shallow MLD, which could hold fresh TOC near the surface. Downward TOC flux from the surface to below the seasonal thermocline was estimated for the processes of winter convection (Fc), turbulent diffusion (Fd) and sinking flux (Fp). The sum of these fluxes accounts for 6–75% of annual new production. To our knowledge, this is the first estimation based on the simultaneous measurement of Fc, Fd, Fp, and annual new production.
On the spatial structure of coastal circulation off Newport, Oregon, during spring and summer 2001 in a region of varying shelf width
Authors: Kosro P. Michael
Published: October 2005

A time series of hourly surface current maps in the shelf waters off Newport, Oregon, was made during April–September 2001 using five SeaSonde HF current mappers, during Coastal Advances in Shelf Transport (COAST). The surface currents responded rapidly to the changing winds, in repeated patterns that were strongly affected by bottom topography. An equatorward current jet repeatedly formed in response to upwelling winds, its strength, but not its trajectory, covarying with the meridional wind stress. Near Cape Foulweather (44.8°N), where the shelf begins to widen, the jet rotates, weakens, and trends offshore to the south first along, then across, the isobaths. Below Cape Foulweather, inshore of the jet, a lee region of generally weak currents was commonly observed. The equatorward jet core was most commonly observed near the 80‐m isobath between 45.0°N and 44.4°N, but transited offshore between spring and summer over Heceta Bank. At Newport (44.6°N), it was rarely observed less than 8 km from the coast. A second, inshore, equatorward jet, previously unknown, was observed repeatedly south of Waldport (44.4°N). Sustained downwelling wind episodes produced poleward currents, though less responsively north of Cape Foulweather. Strongest poleward flow was generally trapped near the coast. Surface currents were correlated with the northward wind, except regionally far from shore over Heceta Bank, responding within half a day. Response to the wind varies spatially, being intensified in the narrow shelf (northern) region. The equatorward jet persists through periods of zero wind forcing. Coastal sea level covaries with the meridional wind and the primary mode of ocean current response.
Polarization properties of reflector antennas used as radio telescopes
Authors: Ng T. , Landecker T. L. , Cazzolato F. , Routledge D. , Gray A. D. , Reid R. I. , Veidt B. G.
Published: October 2005

The distribution of cross polarization across the main beam and near sidelobes of a reflector antenna is calculated. Results are expressed in terms relevant to imaging in radio astronomy, using Stokes parameters, as plots of instrumental polarization Q/I, U/I, and V/I, showing conversion of total intensity of a signal which is unpolarized into apparent linear and circular polarization. The calculations use GRASP8, software that is based on physical optics and the physical theory of diffraction. For purposes of calculation, the symmetrical paraboloidal reflector (diameter ∼40 wavelengths) is fed at the prime focus with a linearly polarized signal. Computed radiation patterns at a number of feed orientations are averaged to establish the antenna response to an unpolarized radio astronomy signal. The results of the computations are consistent with measurements of instrumental polarization of the Dominion Radio Astrophysical Observatory Synthesis Telescope at 1420 MHz made using unpolarized radio sources. For this telescope, the dominant source of instrumental polarization across the field is the cross polarization of the feed. The next most significant effect is scattering by the feed struts; both three‐strut and four‐strut configurations are examined. Struts affect performance in linear polarization but also introduce some instrumental circular polarization. The contribution to instrumental polarization from the reflector itself is comparatively small. Roughness of the reflector surface has relatively little effect in the main beam in Q and U but introduces V and also randomizes the polarization of the sidelobes. In all cases considered, the computations show that the first and subsequent sidelobes are highly polarized, with levels of instrumental polarization up to 50%.
Morphodynamics of small‐scale superimposed sand waves over migrating dune bed forms
Authors: Venditti Jeremy G. , Church Michael , Bennett Sean J.
Published: October 2005

The kinematics and morphodynamics of low‐amplitude, small‐scale sand waves developed over migrating dunes are examined using data drawn from laboratory experiments. We refer to the superimposed features as “sand sheets,” a general descriptive term for low‐amplitude bed waves that are not easily classified as ripples, dunes, or bars. Within the experiments, the sheets formed downstream of the reattachment point at a distance that was invariant with dune size. Some sheets lacked slip faces composed of sand grains avalanching down a slope near the angle of repose. Over equilibrium dunes, three to four sand sheets were observed per 100 s. Sheet thickness was 10% of the height of the dune upon which they were superimposed; they migrated at 8 to 10 times the dune rate; they had nearly constant lengths over the full range of dune lengths and flow conditions; and they had aspect ratios of ∼0.025. Dunes and sand sheets represent distinct scales of sediment transport with different migration rates. However, sediment transport rates, calculated from the sand sheet and dune morphologies, are nearly identical. For transport equivalence to occur, sand sheets migrating at 10 times the dune rate must be 0.1 times the size, which is consistent with the morphological observations. Superimposed bed waves on dunes are often considered simply as additional roughness elements, but these results indicate that such bed waves are the agency by which the dune bed form itself moves downstream.
Changing frequency of occurrence of extreme seasonal temperatures under global warming
Authors: Weisheimer Antje , Palmer T. N.
Published: October 2005

Using a multi‐model multi‐scenario ensemble of integrations made for the forthcoming fourth assessment report of the Intergovernmental Panel on Climate Change, the frequency of occurrence of extreme seasonal temperatures at the end of the 21st Century is estimated. In this study an extreme temperature is defined as lying above the 95 percentile of the simulated temperature distribution for 20th Century climate. The model probability of extreme warm seasons is heterogeneous over the globe and rises to over 90% in large parts of the tropics. This would correspond to an average return period of such anomalous warm seasons of almost one year. The reliability of these results is assessed using the bounding box technique, previously used to quantify the reliability of seasonal climate forecasts. It is shown that the dramatic increase in extreme warm seasons arises from the combined effect of a shift and a broadening of the temperature distributions.
Detecting natural influence on surface air temperature change in the early twentieth century
Authors: Nozawa Toru , Nagashima Tatsuya , Shiogama Hideo , Crooks Simon A.
Published: October 2005

We analyze surface air temperature datasets simulated by a coupled climate model forced with different external forcings, to diagnose the relative importance of these forcings to the observed warming in the early 20th century. The geographical distribution of linear temperature trends in the simulations forced only by natural contributions (volcanic eruptions and solar variability) shows better agreement with observed trends than that does the simulations forced only by well‐mixed greenhouse gases. Using an optimal fingerprinting technique we robustly detect a significant natural contribution to the early 20th century warming. In addition, the amplitude of our simulated natural signal is consistent with the observations. Over the same period, however, we could not detect a greenhouse gas signal in the observed surface temperature in the presence of the external natural forcings. Hence our analysis suggests that external natural factors caused more warming in the early 20th century than anthropogenic factors.
Hurricane intensification detected by continuously monitoring tall precipitation in the eyewall
Authors: Kelley Owen A. , Stout John , Halverson Jeffrey B.
Published: October 2005

Previous studies show that a single observation of tall precipitation in a hurricane's eyewall is often associated with intensification of that hurricane's surface wind. Using WSR‐88D radars, we show that repeated observation of precipitation height provides even more information about wind intensification. If the frequency of tall precipitation in the eyewall is at least 33% (1 in 3 radar volume scans), we find an 82% chance of wind intensification. If this threshold is not met, the chance of wind intensification drops from 82% to just 17%. We show that the WSR‐88D height measurements are reasonable using the TRMM Precipitation Radar.
Saturation anomalies of alkyl nitrates in the tropical Pacific Ocean
Authors: Dahl Elizabeth E. , Yvon‐Lewis Shari A. , Saltzman Eric S.
Published: October 2005

This paper reports the first measurements of the saturation state of low molecular weight alkyl nitrates (methyl, ethyl, isopropyl, and n‐propyl nitrate) in the tropical Pacific Ocean. These compounds were supersaturated with saturation anomalies as high as 2000%. Air/sea flux estimates based on these measurements suggest that surface ocean emissions are sufficient to account for observed levels of tropospheric alkyl nitrates in this region. Model calculations suggest that atmospheric loss rates are faster than can be explained by photolysis and reaction with OH alone. The implication is that removal via transport is important, and there must be a net export of alkyl nitrates from the tropics to other regions of the atmosphere.
Past and future changes in biogenic volatile organic compound emissions simulated with a global dynamic vegetation model
Authors: Lathière J. , Hauglustaine D. A. , De Noblet‐Ducoudré N. , Krinner G. , Folberth G. A.
Published: October 2005

Based on an interactive global biogenic emission and dynamic vegetation model, we investigate the evolution of volatile organic compound (VOC) emissions by the terrestrial biosphere in four scenarios: the Last Glacial Maximum (21,000 years BP), the preindustrial (1850s), present‐day (1990s) and the future (2100). The combined effects of foliar expansion, climate change and ecosystems redistribution impact strongly on biogenic emissions. Total biogenic VOC emissions increase from 331 TgC/yr at the LGM to 702 TgC/yr at the preindustrial, 725 TgC/yr at present‐day and to 1251 TgC/yr under future conditions. If the tropics remain a major source region, a substantial decrease in VOC emissions is calculated over Amazonia for 2100 due to the recession of tropical forests in response to climate change. The Northern Hemisphere becomes a significant source of VOC in the future and globally, emissions increase by 27% for isoprene and 51% for monoterpenes compared to the present.
On the difference in the seasonal cycle of rainfall over India in the Community Climate System Model (CCSM2) and Community Atmospheric Model (CAM2)
Authors: Nanjundiah Ravi S. , Vidyunmala V. , Srinivasan J.
Published: October 2005

The Community Climate System Model (CCSM2) provides a realistic simulation of seasonal cycle of rainfall over India. The Community Atmosphere Model (CAM2), which is the atmospheric component of CCSM2, when forced with observed monthly mean SST, does not simulate accurately the seasonal cycle of rainfall over India. This unusual behaviour is investigated by using a diagnostic model. The rainfall simulated by both CCSM2 and CAM2 is much higher than observed for a value of given vertical integrated water vapor (Pwat). The main difference between the two models is the seasonal variation of Pwat. Pwat in CAM2 is larger than CCSM2 in the month of May over India. This is on account of the advection of air with high Pwat from Arabian Sea to Indian region. In CCSM2, Pwat is not high because the simulated SST in the Arabian sea in CCSM2 is 2°C lower than observed. Hence the combined effect of lower Pwat and a steeper gradient in the Pwat‐rainfall relationship cause the simulation of seasonal cycle of rainfall in CCSM2 to be realistic.
Wave number spectrum and mean square slope of intermediate‐scale ocean surface waves
Authors: Hwang Paul A.
Published: October 2005

This paper presents an analysis of the wave number spectra of intermediate‐scale waves (wavelengths between 0.02 and 6 m) covering a wide range of wind and background wave conditions under various sea‐state conditions. The main result of the analysis is that the dependence of the dimensionless wave spectrum on the dimensionless wind friction velocity follows a power law function. The coefficient and exponent of the power law function vary systematically with the wave number. The wave number dependence of the coefficient and exponent serves as an empirical parameterization for computing the wave number spectra of intermediate‐scale waves at different wind speeds. Calculation of the mean square slope from the resulting wave number spectrum confirms that intermediate‐scale waves are the dominant contributor of the ocean surface roughness. A simple formula is presented for calculating the band‐pass filtered mean square slope of the ocean surface for remote sensing applications.
Ozone profile and tropospheric ozone retrievals from the Global Ozone Monitoring Experiment: Algorithm description and validation
Authors: Liu X. , Chance K. , Sioris C. E. , Spurr R. J. D. , Kurosu T. P. , Martin R. V. , Newchurch M. J.
Published: October 2005

Ozone profiles are derived from back scattered radiance spectra in the ultraviolet (289–339 nm) measured by the Global Ozone Monitoring Experiment (GOME) using the optimal estimation technique. Tropospheric Column Ozone (TCO) is directly derived using the known tropopause to divide the stratosphere and troposphere. To optimize the retrieval and improve the fitting precision needed for tropospheric ozone, we perform extensive wavelength and radiometric calibrations and improve forward model inputs. The a priori influence of retrieved TCO is ∼15% in the tropics and increases to ∼50% at high latitudes. The dominant error terms are the smoothing errors, instrumental random‐noise errors, and systematic temperature errors. We compare our GOME retrievals with Earth‐Probe Total Ozone Mapping Spectrometer (TOMS) Total column Ozone (TO), Dobson/Brewer (DB) TO, and ozonesonde TCO at 33 World Ozone and Ultraviolet Radiation Data Centre (WOUDC) stations between 71°S and 75°N during 1996–1999. The mean biases with TOMS and DB TO are within 6 DU (2%, 1 DU = 2.69 × 1016 molecules cm−2) at most of the stations. The retrieved Tropospheric Column Ozone (TCO) captures most of the temporal variability in ozonesonde TCO; the mean biases are mostly within 3 DU (15%) and the standard deviations (1σ) are within 3–8 DU (13–27%). We also compare our retrieved ozone profiles above ∼15 km against Stratospheric Aerosol and Gas Experiment II measurements from 1996 to 1999. The mean biases and standard deviations are usually within 15%.
A 70‐kyr sea surface temperature record off southern Chile (Ocean Drilling Program Site 1233)
Authors: Kaiser J. , Lamy F. , Hebbeln D.
Published: October 2005

We present the first high‐resolution alkenone‐derived sea surface temperature (SST) reconstruction in the southeast Pacific (Ocean Drilling Program Site 1233) covering the major part of the last glacial period and the Holocene. The record shows a clear millennial‐scale pattern that is very similar to climate fluctuations observed in Antarctic ice cores, suggesting that the Southern Hemisphere high‐latitude climate changes extended into the midlatitudes, involving simultaneous changes in air temperatures over Antarctica, sea ice extent, extension of the Antarctic Circumpolar Current, and westerly atmospheric circulation. A comparison to other midlatitude surface ocean records suggests that this “Antarctic” millennial‐scale pattern was probably a hemisphere‐wide phenomenon. In addition, we performed SST gradient reconstructions over the complete latitudinal range of the Pacific Eastern Boundary Current System for different time intervals during the last 70 kyr. The main results suggest an equatorward displaced subtropical gyre circulation during marine isotope stages 2 and 4.
Tropical Pacific climate response to obliquity forcing in the Pleistocene
Authors: Lee S.‐Y. , Poulsen C. J.
Published: October 2005

Marine proxy records of Pleistocene seawater temperature and productivity in the tropical Pacific Ocean vary over a 41,000‐year period that has been attributed to Earth's obliquity cycle. The proxy records are paradoxical both because obliquity has a small effect on low‐latitude insolation and because tropical seawater temperature and productivity were anticorrelated with obliquity insolation forcing. In this study, we investigate the response of the tropical Pacific climate to obliquity forcing using a coupled ocean‐atmosphere model to reconcile the proxy records with climate theory. Two glacial and two modern simulations were completed with extreme high and low axial tilts of 24.5° and 22.2°. In response to an increase in axial tilt, tropical sea surface temperatures decrease by as much as 0.8°C because of the local reduction in insolation. Subsurface water temperatures in the eastern and central equatorial Pacific increase by nearly 1°C. Anomalous heating through high‐obliquity forcing also generates dynamical responses that weaken mean annual midlatitude westerlies and subtropical trade winds, contributing to a ∼20% reduction in the subtropical gyre circulation. Analyses using a Lagrangian transport model indicate that low‐latitude subsurface warming is due to a reduction in heat export from the tropics and the advection and ventilation of anomalously warm South Pacific extratropical waters through the thermocline circulation. The model's response to obliquity is consistent with Pleistocene proxy data that indicate the tropical Walker circulation and thermocline slope were not strongly influenced by changes in axial tilt. The model results also support the hypothesis that Earth's obliquity influences climate through its control on meridional insolation gradients.
Histone H3.3 deposition at E2F‐regulated genes is linked to transcription
Authors: Daury Laetitia , Chailleux Catherine , Bonvallet Julie , Trouche Didier
Published: October 2005

The histone variant H3.3 can be incorporated in chromatin independently of DNA synthesis. By imaging using green fluorescent protein‐tagged histones, H3.3 deposition has been found to be linked with transcriptional activation. Here, we investigated H3.3 incorporation during G1 progression on cell‐cycle‐regulated E2F‐dependent genes and on some control loci. We transiently transfected resting cells with an expression vector for tagged H3.3 and we analysed its presence by chromatin immunoprecipitation. We found that replication‐independent H3.3 deposition occurred on actively transcribed genes, but not on silent loci, thereby confirming its link with transcription. Interestingly, we observed similar levels of H3.3 occupancy on promoters and on the coding regions of the corresponding genes, indicating that H3.3 deposition is not restricted to promoters. Finally, H3.3 occupancy correlated with the presence of transcription‐competent RNA polymerase II. Taken together, our results support the hypothesis that H3.3 is incorporated after disruption of nucleosomes mediated by transcription elongation.
Possible Association of the Human KCNE1 (minK) Gene and QT Interval in Healthy Subjects: Evidence from Association and Linkage Analyses in Israeli Families
Authors: Friedlander Y. , Vatta M. , Sotoodehnia N. , Sinnreich R. , Li H. , Manor O. , Towbin J. A. , Siscovick D. S. , Kark J. D.
Published: October 2005

QT interval prolongation is associated with increased risk of sudden and non‐sudden cardiac death. Potassium channel gene variants are associated with inherited long QT syndromes. Using linkage and association analyses, we investigated whether variants in the potassium channel subunit KCNE1 are associated with QTc intervals in an unselected population sample of 80 kindreds living in kibbutz settlements in Israel. Variance‐component linkage analysis revealed weak evidence of linkage of KCNE1 polymorphisms with QTc intervals. Family‐based association analysis showed a significant association between the G38S polymorphism and QTc interval. Further quantitative trait association analysis demonstrated a significant residual heritability component (h2= 0.33), and that the effect of the G38S variant allele is modified by gender. Estimated maximum likelihood parameters from these models indicated that male gender, age, hypertension, diabetes, hypercholesterolemia, fibrinogen and BMI were positively associated with QTc interval; level of education and cigarette smoking showed an inverse association. Both erythrocyte membrane n‐6 and n‐3 fatty acids showed a significant inverse association with QTc interval. While more than 15.8% of QTc variability was contributed by covariates, another 4.7% was explained by dietary factors, the G38S polymorphism explained 2.2%, and approximately 36% was explained by polygenes. An in silico analysis showed also that the novel V80 SNP, another KCNE1 synonymous variant, abolishes the recognition for a splicing enhancer, which may lead to an increased effect of the G38S mutation.

These results demonstrate that, in addition to polygenic background, dietary factors and other covariables, the KCNE1 G38S variant is involved in determining QTc levels in this population‐based sample of families.
Diversity and Divergence Among the Tribal Populations of India
Authors: Watkins W.S. , Prasad B. V. R. , Naidu J. M. , Rao B. B. , Bhanu B. A. , Ramachandran B. , Das P. K. , Gai P. B. , Reddy P. C. , Reddy P. G. , Sethuraman M. , Bamshad M. J. , Jorde L. B.
Published: October 2005

Tribal populations of the Indian subcontinent have been of longstanding interest to anthropologists and human geneticists. To investigate the relationship of Indian tribes to Indian castes and continental populations, we analyzed 45 unlinked autosomal STR loci in 9 tribal groups, 8 castes, and 18 populations from Africa, Europe and East Asia. South Indian tribal populations demonstrate low within‐population heterozygosity (range: 0.54 – 0.69), while tribal populations sampled further north and east have higher heterozygosity (range: 0.69 – 0.74). Genetic distance estimates show that tribal Indians are more closely related to caste Indians than to other major groups. Between‐tribe differentiation is high and exceeds that for eight sub‐Saharan African populations (4.8% vs. 3.7%). Telugu‐speaking populations are less differentiated than non‐Telugu speakers (FST: 0.029 vs. 0.079), but geographic distance was not predictive of genetic affinity between tribes. South Indian tribes show significant population structure, and individuals can be clustered statistically into groups that correspond with their tribal affiliation. These results are consistent with high levels of genetic drift and isolation in Indian tribal populations, particularly those of South India, and they imply that these populations may be potential candidates for linkage disequilibrium and association mapping.
Dipolar interactions, molecular flexibility, and flexoelectricity in bent-core liquid crystals
Authors: Dewar Alastair , Camp Philip J.
Published: October 2005

The effects of dipolar interactions and molecular flexibility on the structure and phase behavior of bent-core molecular fluids are studied using Monte Carlo computer simulations. Some calculations of flexoelectric coefficients are also reported. The rigid cores of the model molecules consist of either five or seven soft spheres arranged in a “V” shape with external bend angle γ. With purely repulsive sphere-sphere interactions and γ=0° (linear molecules) the seven-sphere model exhibits isotropic, uniaxial nematic, and untilted and tilted smectic phases. With γ⩾20° the untilted smectic phases disappear, while the system with γ⩾40° shows a direct tilted smectic-isotropic fluid transition. The addition of electrostatic interactions between transverse dipole moments on the apical spheres is generally seen to reduce the degree of molecular inclination in tilted phases, and destabilizes the nematic and untilted smectic phases of linear molecules. The effects of adding three-segment flexible tails to the ends of five-sphere bent-core molecules are examined using configurational-bias Monte Carlo simulations. Only isotropic and smectic phases are observed. On the one hand, molecular flexibility gives rise to pronounced fluctuations in the smectic-layer structure, bringing the simulated system in better correspondence with real materials; on the other hand, the smectic phase shows almost no tilt. Lastly, the flexoelectric coefficients of various nematic phases—with and without attractive sphere-sphere interactions—are presented. The results are encouraging, but a large computational effort is required to evaluate the appropriate fluctuation relations reliably.
Quasigeostrophic model of the instabilities of the Stewartson layer in flat and depth-varying containers
Authors: Schaeffer Nathanaël , Cardin Philippe
Published: October 2005

Detached shear layers in a rotating container, known as Stewartson layers, become unstable for a critical shear measured by the Rossby number Ro. To study rapidly rotating flows at asymptotically small Rossby and Ekman numbers E, a quasigeostrophic (QG) model is developed, whose main original feature is to enforce mass conservation properly, and valid for any container provided that the top and bottom have finite slopes. Asymptotic scalings of the Stewartson instability are deduced from the linear QG model, extending the previous analyses to large slopes (as in a sphere). For a flat container, the critical Rossby number evolves as E3∕4 and the instability can be understood as a shear instability. For a depth-varying container, the instability is quite different: it is a Rossby wave with a critical Rossby number proportional to βE1∕2, where β is related to the slope. A numerical implementation of the QG model is used to determine the critical parameters for different Ekman numbers (as low as 10−10) and to describe the instability at the onset for different geometries. We also investigate the asymmetry between positive and negative Ro and propose an explanation based on the location of the instability. For flat cylindrical containers, the QG numerical results are directly compared to existing experimental data obtained by Niino and Misawa [J. Atmos. Sci. 41, 1992 (1984)] and Fruh and Read [J. Fluid Mech. 383, 143 (1999)]. We present new experimental results of the destabilization of a Stewartson layer in a rotating spheroid, caused by the differential rotation of two disks or a central inner core. These experiments are compared to the numerical QG results obtained in a split sphere, validating the QG model, and allowing us to show its limits. For spherical shells, the experimental critical curves agree to the ones obtained by three-dimensional calculations of Hollerbach [J. Fluid Mech. 492, 289 (2003)].
Gauge theory on nonassociative spaces
Authors: Majid S.
Published: October 2005

We show how to do gauge theory on the octonions and other nonassociative algebras such as “quasi-R4” models proposed in string theory. We use the theory of quasialgebras obtained by cochain twist introduced previously. The gauge theory in this case is twisting–equivalent to the usual gauge theory on the underlying classical space. We give a general U(1)-Yang–Mills example for any quasialgebra and a full description of the moduli space of flat connections in this theory for the cube Z23 and hence for the octonions. We also obtain further results about the octonions themselves; an explicit Moyal-product description of them as a nonassociative quantization of functions on the cube, and a characterization of their cochain twist as invariant under Fourier transform.
Noncommutative model with spontaneous time generation and Planckian bound
Authors: Majid S.
Published: October 2005

We illustrate the thesis that if time did not exist, we would have to create it if space is noncommutative, and extend functions by something like Schrödinger’s equation. We propose that the phenomenon is a somewhat general mechanism within noncommutative geometry for “spontaneous time generation.” We show in detail how this works for the su2 algebra [xi,xj]=2ιλϵijkxk as noncommutative space, by explicitly adjoining the forced time variable. We find the natural induced noncommutative Schrödinger’s equation and show that it has the correct classical limit for a particle of some mass m≠0, which is generated as a second free parameter by the theory. We show that plane waves exist provided ∣p⃗∣<π∕2λ, i.e., we find a Planckian bound on spatial momentum. We also propose dispersion relations ∣∂p0∕∂p⃗∣=∣tan(λ∣p⃗∣)∣∕mλ for the model and explore some elements of the noncommutative geometry. The model is complementary to our previous bicrossproduct one.
Ground state energy of the polaron in the relativistic quantum electrodynamics
Authors: Sasaki Itaru
Published: October 2005

We consider the polaron model in the relativistic quantum electrodynamics. We prove that the ground state energy of the model is finite for all values of the fine-structure constant and the ultraviolet cutoff Λ. Moreover we give an upper bound and a lower bound of the ground state energy.
Three-dimensional dynamic Monte Carlo simulations of elastic actin-like ratchets
Authors: Burroughs N. J. , Marenduzzo D.
Published: October 2005

We present three-dimensional dynamic Monte Carlo simulations of the growth of a semiflexible fiber against a fluctuating obstacle. The natural reference for our numerical study are the elastic and Brownian ratchet models previously analyzed semianalytically. We find that the decay of the velocity versus applied load is exponential to a good degree of accuracy, provided we include in the load the drag force felt by the moving obstacle. If the fiber and obstacle only interact via excluded volume, there are small corrections to the Brownian ratchet predictions which suggest that tip fluctuations play a minor role. If on the other hand fiber and obstacle interact via a soft potential, the corrections are much larger when the obstacle diffuses slowly. This means that microscopic assumptions can profoundly affect the dynamics. We also identify and characterize a novel “pushing catastrophe”—which is distinct from the usual fiber buckling—in which the growth of the fiber decouples from the obstacle movement. The time distribution of catastrophes can be explained via an approximate analytical treatment, and our numerics suggest that the time taken to lose propulsive force is largely dependent on the fiber incidence angle. Our results are a first step in realizing numerical polymer models for the motion of sets or networks of semiflexible fibers close to a fluctuating membrane or obstacle.
Cross sections of the O++H2→OH++H ion-molecule reaction and isotopic variants (D2, HD): Quasiclassical trajectory study and comparison with experiments
Authors: Martínez Rodrigo , Sierra José Daniel , González Miguel
Published: October 2005

A dynamics study [cross section and microscopic mechanism versus collision energy (ET)] of the reaction O++H2→OH++H, which plays an important role in Earth’s ionosphere and interstellar chemistry, was conducted using the quasiclassical trajectory method, employing an analytical potential energy surface (PES) recently derived by our group [R. Martínez et al., J. Chem. Phys. 120, 4705 (2004)]. Experimental excitation functions for the title reaction, as well as its isotopic variants with D2 and HD, were near-quantitatively reproduced in the calculations in the very broad collision energy range explored (ET=0.01–6.0eV). Intramolecular and intermolecular isotopic effects were also examined, yielding data in good agreement with experimental results. The reaction occurs via two microscopic mechanisms (direct and nondirect abstraction). The results were satisfactorily interpreted based on the reaction probability and the maximum impact parameter dependences with ET, and considering the influence of the collinear [OHH]+ absolute minimum of the PES on the evolution from reactants to products. The agreement between theory and experiment suggests that the reaction mainly occurs through the lowest energy PES and nonadiabatic processes are not very important in the wide collision energy range analyzed. Hence, the PES used to describe this reaction is suitable for both kinetics and dynamics studies.
Spin state evolution and magnetic anisotropy of elongated Ni80Fe20 nanorings
Authors: Adeyeye A. O. , Singh N. , Goolaup S.
Published: October 2005

We have investigated the evolution of magnetic spin states and in-plane magnetic anisotropy in arrays of elongated Ni80Fe20 rings. Large area (4×4mm2) elongated Ni80Fe20 nanorings of thickness in the range from 5to60nm were fabricated using deep ultraviolet lithography at 248nm exposing wavelength. The magnetic spin states and the magnetization reversal processes are strongly dependent on the ring thickness and in-plane magnetic anisotropy due to the elongation of the rings. Our experimental results are in a very good agreement with micromagnetic simulations.
Effects of frustration, confinement, and surface interactions on the dimerization of an off-lattice β-barrel protein
Authors: Griffin Mary A. , Friedel Miriam , Shea Joan-Emma
Published: October 2005

We study the effects of confinement, sequence frustration, and surface interactions on the thermodynamics of dimerization of an off-lattice minimalist β-barrel protein using replica exchange molecular dynamics. We vary the degree of frustration of the protein by tuning the specificity of the hydrophobic interactions and investigate dimerization in confining spheres of different radii. We also investigate surface effects by tethering the first residue of one of the proteins to a uniformly repulsive surface. We find that increasing the confinement and frustration stabilize the dimer, while adding a repulsive surface decreases its stability. Different ensembles of structures, including properly dimerized and various partially dimerized states, are observed at the association transition temperature Ta, depending on the amount of frustration and whether a surface is present. The presence of a surface is predicted to alter the morphology of larger aggregates formed from partially unfolded dimeric conformations.