bluuebunny/crossref_metadata_2025_split huggingface dataset:
Numerical analysis of absorption and transmission photoacoustic spectra of silicon samples with differently treated surfaces
Authors: Maliński M. , Chrobak Ł. 
Published: October 2010

AbstractThis paper presents results of the photoacoustic (PA) spectral studies, of a series of silicon samples with differently prepared surfaces, in two PA experimental configurations, so-called, absorption and transmission ones. The PA amplitude spectra of the samples indicated existence of the damaged surface layers. In the paper, the two layer mathematical models of a sample with a damaged surface layer that were used for numerical interpretation of the amplitude PA spectra of the investigated samples, are presented and discussed.
Concealment from predators drives foraging habitat selection in brood‐rearing Alpine black grouse Tetrao tetrix hens: habitat management implications
Authors: Signorell Natalina , Wirthner Sven , Patthey Patrick , Schranz Rebekka , Rotelli Luca , Arlettaz Raphaël 
Published: October 2010

AbstractDeclines of Alpine black grouse Tetrao tetrix populations have been linked to increasing disturbance by recreation and degradation of breeding habitat due to changes in land‐use, especially abandonment of traditional farming practices. Appropriate forest, shrubland and grassland management may mitigate the negative effects of land abandonment. The habitat associations and trophic requirements of brood‐rearing Alpine black grouse hens were appraised to inform effective habitat management policies. We measured the abundance, biomass and phenology of arthropods, a key food source for grouse chicks, in eight timberline habitat categories and performed a habitat selection analysis based on radio‐tracking data collected from eight brood‐rearing hens in the Swiss and Italian Alps. Arthropod biomass differed significantly between habitat categories and peaked in early summer due to a sharp increase of orthopterans (Saltatoria), an essential food source for Alpine black grouse chicks. Open grassland and grassy shrubland yielded the highest arthropod biomass, with Saltatoria dominating the sample. Yet, brood‐rearing hens avoided open grassland, opting for a mosaic of grassy shrubland with scattered trees. Chick‐rearing hens apparently traded‐off food abundance for reduced predation risk, i.e. habitats offering cover for concealment and escape from predators. These specific black grouse breeding habitat requirements inform about habitat management within Alpine timberline ecosystems. Managers should not restore extensive, homogeneous pasturelands. Instead, a complex heterogeneous habitat mosaic, consisting of patches of grassland and shrubland interspersed with scattered coniferous trees should be promoted.
A method for inferring extinction based on sighting records that change in frequency over time
Authors: Jarić Ivan , Ebenhard Torbjörn 
Published: October 2010

AbstractIt is a very important, but also a very difficult task, to establish how long a certain species has to remain unregistered before we can declare it extinct. The wrong assumption regarding species extinction could result in a type I or type II statistical error, leading to inappropriate management actions or even species extinction. Recent development of the methods for inferring the threat of extinction, when the only available information is a record of sightings, has enabled a quantitative approach to the problem. In our study we present an index that infers extinction probability based on trends in sighting intervals. Our study comprises a description of the sighting trend index, a sensitivity analysis and an application of the index to the sighting record of the black‐footed ferret Mustela nigripes. The main advantage of this method could be its sensitivity to changes in sighting frequency within the sighting record. However, further testing of the method on different data sets could be important for gaining additional knowledge regarding its adequate application in the field of conservation biology.
Origin of the outburst flood from Glacier de Tête Rousse in 1892 (Mont Blanc area, France)
Authors: Vincent C. , Garambois S. , Thibert E. , Lefèbvre E. , Le Meur E. , Six D. 
Published: October 2010

AbstractExtensive field measurements and historical data have been used to re-analyse the cause of the outburst flood from Glacier de Tête Rousse that devastated the village of Saint-Gervais–Le Fayet, French Alps in 1892, causing 175 fatalities. The origin of this disaster was the rupture of an intraglacial cavity in Glacier de Tête Rousse that released 200 000 m3of water and ice. All previous studies have concluded that the intraglacial cavity was formed from a crevasse that was filled and enlarged by meltwater. The re-analysis presented here suggests that the reservoir of the upper cavity did not originate as an enlarging crevasse. The origin of the meltwater reservoir was more likely a supraglacial lake formed before 1878 during a period of negative mass balance. Following a period of positive mass balance after 1878, the lake was hidden until the outburst flood of 1892. This means that such hazards may be detected by checking regularly for the formation of a lake on the surface of the glacier before it is hidden.
Light propagation in firn: application to borehole video
Authors: Fudge T.J. , Smith Benjamin E. 
Published: October 2010

AbstractBorehole optical stratigraphy (BOS) is a borehole video system and processing routine for investigating polar firn. BOS records brightness variations in the firn and is effective at identifying stratigraphic markers. BOS brightness logs have been used to count annual layers and measure vertical strain, even though a specific cause of the brightness variations has not been determined. Here we combine two models of light transport to examine potential errors with BOS and identify improvements which will allow the system to estimate optical grain size. We use a Monte Carlo radiative transfer model to estimate the influence of firn microstructure variations on borehole reflectance. We then use a ray-tracing algorithm to model the multiple reflections within the borehole that cause measured brightness variations. Multiple reflections cause the brightness measured at a point on the borehole wall to not necessarily be equal to the local wall reflectance. The ray tracing further shows that wall imperfections or variations in the camera position can produce brightness variations that are unrelated to changes in firn properties. Smooth walls and good stabilization of the camera help ensure that brightness variations result from variations in firn properties, and thus are a measure of firn stratigraphy, rather than artifacts.
Present stability of the Larsen C ice shelf, Antarctic Peninsula
Authors: Jansen D. , Kulessa B. , Sammonds P.R. , Luckman A. , King E.C. , Glasser N.F. 
Published: October 2010

AbstractWe modelled the flow of the Larsen C and northernmost Larsen D ice shelves, Antarctic Peninsula, using a model of continuum mechanics of ice flow, and applied a fracture criterion to the simulated velocities to investigate the ice shelf’s present-day stability. Constraints come from satellite data and geophysical measurements from the 2008/09 austral summer. Ice-shelf thickness was derived from BEDMAP and ICESat data, and the density–depth relationship was inferred from our in situ seismic reflection data. We obtained excellent agreements between modelled and measured ice-flow velocities, and inferred and observed distributions of rifts and crevasses. Residual discrepancies between regions of predicted fracture and observed crevasses are concentrated in zones where we assume a significant amount of marine ice and therefore altered mechanical properties in the ice column. This emphasizes the importance of these zones and shows that more data are needed to understand their influence on ice-shelf stability. Modelled flow velocities and the corresponding stress distribution indicate that the Larsen C ice shelf is stable at the moment. However, weakening of the elongated marine ice zones could lead to acceleration of the ice shelf due to decoupling from the slower parts in the northern inlets and south of Kenyon Peninsula, leading to a velocity distribution similar to that in the Larsen B ice shelf prior to its disintegration.
Basal melt rates beneath Whillans Ice Stream, West Antarctica
Authors: Beem Lucas H. , Jezek Ken C. , Van Der Veen C.J. 
Published: October 2010

AbstractBasal water lubricates and enables the fast flow of the West Antarctic ice streams which exist under low gravitational driving stress. Identification of sources and rates of basal meltwater production can provide insight into the dynamics of ice streams and the subglacial hydrology, which remain insufficiently described by glaciological theory. Combining measurements and analytic modeling, we identify two regions where basal meltwater is produced beneath Whillans Ice Stream, West Antarctica. Downstream of the onset of shear crevasses, strong basal melt (20–50 mm a−1) is concentrated beneath the relatively narrow shear margins. Farther upstream, melt rates are consistently 3–7 mm a−1 across the width of the ice stream. We show that the transition in melt-rate patterns is coincident with the onset of shear margin crevassing and streaming flow and related to the development of significant lateral shear resistance, which reorganizes the resistive stress regime and induces a concentration of basal resistance adjacent to the shear margin. Finally, we discuss how downstream freeze-on in the ice-stream center coupled with melt beneath the shear margin might result in a slowing but widening ice stream.
The importance of considering depth-resolved photochemistry in snow: a radiative-transfer study of NO2 and OH production in Ny-Ålesund (Svalbard) snowpacks
Authors: France J.L. , King M.D. , Lee-Taylor J. 
Published: October 2010

AbstractSolar visible radiation can penetrate 2–30 cm (e-folding depth) into snowpacks and photolyse nitrate anions and hydrogen peroxide contained in the snow. Photolysis rate coefficients, J, for NO3− and H2O2 photolysis are presented for a melting and a fresh snowpack at Ny-Ålesund, Svalbard. Calculations of (a) transfer velocities, υ, and molecular fluxes of gaseous NO2 from the snowpack and (b) depth-integrated production rates of OH radicals within the snowpack are presented. The results show the importance of considering the depth dependence, i.e. not just the snow surface, when modelling snowpack photochemistry. Neglecting photochemistry under the snow surface can result in an apparent larger molecular flux of NO2 from NO3− photolysis than the melting snowpack. However, when the depth-resolved molecular fluxes of NO2 within the snowpack are calculated, a larger NO2 flux may be apparent in the melting snowpack than the fresh snowpack. For solar zenith angles of 60°, 70° and 80° the modelled molecular fluxes of NO2 from fresh snowpack are 11.6, 5.6 and 1.7 nmol m−2 h−1, respectively, and those for melting snowpack are 19.7, 9.1 and 2.9 nmol m−2 h−1, respectively.
Comparison of satellite, thermochron and air temperatures at Summit, Greenland, during the winter of 2008/09
Authors: Koenig Lora S. , Hall Dorothy K. 
Published: October 2010

AbstractCurrent trends show a rise in Arctic surface and air temperatures, including over the Greenland ice sheet where rising temperatures will contribute to increased sea-level rise through increased melt. We aim to establish the uncertainties in using satellite-derived surface temperature for measuring Arctic surface temperature, as satellite data are increasingly being used to assess temperature trends. To accomplish this, satellite-derived surface temperature, or land-surface temperature (LST), must be validated and limitations of the satellite data must be assessed quantitatively. During the 2008/09 boreal winter at Summit, Greenland, we employed data from standard US National Oceanic and Atmospheric Administration (NOAA) air-temperature instruments, button-sized temperature sensors called thermochrons and the Moderate Resolution Imaging Spectroradiometer (MODIS) satellite instrument to (1) assess the accuracy and utility of thermochrons in an ice-sheet environment and (2) compare MODIS-derived LSTs with thermochron-derived surface and air temperatures. The thermochron-derived air temperatures were very accurate, within 0.1 ± 0.3°C of the NOAA-derived air temperature, but thermochron-derived surface temperatures were ∼3°C higher than MODIS-derived LSTs. Though surface temperature is largely determined by air temperature, these variables can differ significantly. Furthermore, we show that the winter-time mean air temperature, adjusted to surface temperature, was ∼11°C higher than the winter-time mean MODIS-derived LST. This marked difference occurs largely because satellite-derived LSTs cannot be measured through cloud cover, so caution must be exercised in using time series of satellite LST data to study seasonal temperature trends.
Joint Acceptance and Scientific Change: A Case Study
Authors: Andersen Hanne 
Published: October 2010

ABSTRACTRecently, several scholars have argued that scientists can accept scientific claims in a collective process, and that the capacity of scientific groups to form joint acceptances is linked to a functional division of labor between the group members. However, these accounts reveal little about how the cognitive content of the jointly accepted claim is formed, and how group members depend on each other in this process. In this paper, I shall therefore argue that we need to link analyses of joint acceptance with analyses of distributed cognition. To sketch how this can be done, I shall present a detailed case study, and on the basis of the case, analyze the process through which a group of scientists jointly accept a new scientific claim and at a later stage jointly accept to revise previously accepted claims. I shall argue that joint acceptance in science can be established in situations where an overall conceptual structure is jointly accepted by a group of scientists while detailed parts of it are distributed among group members with different areas of expertise, a condition that I shall call a heterogeneous conceptual consensus. Finally, I shall show how a heterogeneous conceptual consensus can work as a constraint against scientific change and address the question how changes may nevertheless occur.
Other tetraploid species and conspecific diploids as sources of genetic variation for an autotetraploid
Authors: Stift Marc , Bregman Rob , Oostermeijer J. Gerard B. , van Tienderen Peter H. 
Published: October 2010

•Premise of the study:Most plants are polyploid and have more than two copies of the genome. The evolutionary success of polyploids is often attributed to their potential to harbor increased genetic variation, but it is poorly understood how polyploids can attain such variation. Because of their formation bottleneck, newly formed tetraploids start out with little variation. Tetraploids may attain genetic variation through a combination of new mutations, recurrent formation, and gene exchange with diploid ancestors or related tetraploid species. We explore the role of gene exchange and introgression in autotetraploidRorippa amphibia, a species that harbors more genetic variation than its diploid ancestors.•Methods:We crossed autotetraploidR. amphibiato diploid conspecifics and tetraploidR. sylvestrisand backcrossed resulting F1hybrids. We used flow cytometry to determine the ploidy of all progeny.•Key results:Tetraploids ofR. amphibiaandR. sylvestriswere interfertile; F1hybrids were fertile and could backcross. Crosses between diploids and tetraploids yielded a small number of viable, often tetraploid progeny. This indicates that unreduced gametes can facilitate gene flow from diploids to tetraploids. We detected a frequency of unreduced gametes of around 2.7 per 1000, which was comparable between diploids and tetraploids.•Conclusions:Introgression from tetraploidR. sylvestrisprovides a realistic source of variation in autotetraploidR. amphibia. Only in a scenario where other compatible partners are absent, for example immediately after tetraploidization, gene flow through unreduced gametes from diploids could be an important source of genetic variation for tetraploids.
Inhibition of Terminal Differentiation of B Cells Mediated by CD27 and CD40 Involves Signaling through JNK
Authors: Satpathy Shuchismita , Shenoy Gautam N. , Kaw Sheetal , Vaidya Tushar , Bal Vineeta , Rath Satyajit , George Anna 
Published: October 2010

AbstractB cells responding to cognate Ag in vivo undergo clonal expansion that is followed by differentiation into Ab-secreting plasma cells or into quiescent restimulable memory. Both these events occur in the germinal center and require that cells exit from proliferation, but the signals that lead to one or the other of these mutually exclusive differentiation pathways have not been definitively characterized. Previous experiments have shown that signals transduced through the TNFRs CD27 and CD40 at the time of B cell stimulation in vitro or in vivo can influence this cell fate decision by inhibiting terminal differentiation and promoting memory. In this study, we show that the PIQED domain of the cytoplasmic tail of murine CD27 and the adapter molecule TNFR-associated factor 2 are involved in this effect. Using pharmacological inhibitors of signaling intermediates, we identify JNK as being necessary and sufficient for the observed inhibition of terminal differentiation. While JNK is involved downstream of CD40, inhibition of the MEK pathway can also partially restore plasma cell generation, indicating that both signaling intermediates may be involved. We also show that inhibition of induction of IFN regulatory factor 4 and B lymphocyte induced maturation protein 1 are downstream events common to both receptors.
The Interactions of Multiple Cytokines Control NK Cell Maturation
Authors: Brady Jason , Carotta Sebastian , Thong Rebecca P. L. , Chan Christopher J. , Hayakawa Yoshihiro , Smyth Mark J. , Nutt Stephen L. 
Published: October 2010

Abstract
Although NK cells are well known for their cytotoxic functions, they also produce an array of immunoregulatory cytokines and chemokines. During an immune response, NK cells are exposed to complex combinations of cytokines that influence their differentiation and function. In this study, we have examined the phenotypic and functional consequences of exposing mouse NK cells to IL-4, IL-12, IL-15, IL-18, and IL-21 and found that although all factors induced signs of maturation, characterized by decreased proliferation and IFN-γ secretion, distinct combinations induced unique cytokine secretion profiles. In contrast, the immunosuppressive factors IL-10 and TGF-β had little direct effect on NK cell effector functions. Sustained IL-18 signals resulted in IL-13 and GM-CSF production, whereas IL-12 and IL-21 induced IL-10 and TNF-α. Surprisingly, with the exception of IL-21, all cytokines suppressed cytotoxic function of NK cells at the expense of endogenous cytokine production suggesting that “helper-type” NK cells were generated. The cytokine signals also profoundly altered the cell surface phenotype of the NK cells—a striking example being the downregulation of the activating receptor NKG2D by IL-4 that resulted in decreased NKG2D-dependent killing. IL-4 exposure also modulated NKG2D expression in vivo suggesting it is functionally important during immune responses. This study highlights the plasticity of NK cell differentiation and suggests that the relative abundance of cytokines at sites of inflammation will lead to diverse outcomes in terms of NK cell phenotype and interaction with the immune system.
Eotaxin-3/CC Chemokine Ligand 26 Is a Functional Ligand for CX3CR1
Authors: Nakayama Takashi , Watanabe Yoshiko , Oiso Naoki , Higuchi Tomonori , Shigeta Akiko , Mizuguchi Nobuyuki , Katou Fuminori , Hashimoto Kenji , Kawada Akira , Yoshie Osamu 
Published: October 2010

Abstract
Eotaxin-3/CCL26 is a functional ligand for CCR3 and abundantly produced by IL-4–/IL-13–stimulated vascular endothelial cells. CCL26 also functions as a natural antagonist for CCR1, CCR2, and CCR5. In this study, we report that CCL26 is yet a functional ligand for CX3CR1, the receptor for fractalkine/CX3CL1, which is expressed by CD16+ NK cells, cytotoxic effector CD8+ T cells, and CD14lowCD16high monocytes. Albeit at relatively high concentrations, CCL26 induced calcium flux and chemotaxis in mouse L1.2 cells expressing human CX3CR1 but not mouse CX3CR1 and competed with CX3CL1 for binding to CX3CR1. In chemotaxis assays using human PBMCs, CCL26 attracted not only eosinophils but also CD16+ NK cells, CD45RA+CD27−CD8+ T cells, and CD14lowCD16high monocytes. Intraperitoneal injection of CCL26 into mice rapidly recruited mouse eosinophils and intravenously transferred human CD16+ NK cells into the peritoneal cavity. IL-4–stimulated HUVECs produced CCL26 and efficiently induced adhesion of cells expressing CX3CR1. Real-time PCR showed that skin lesions of psoriasis consistently contained CX3CL1 mRNA but not CCL26 mRNA, whereas those of atopic dermatitis contained CCL26 mRNA in all samples but CX3CL1 mRNA in only about half of the samples. Nevertheless, the skin lesions from both diseases consistently contained CX3CR1 mRNA at high levels. Thus, CCL26 may be partly responsible for the recruitment of cells expressing CX3CR1 in atopic dermatitis particularly when the expression of CX3CL1 is low. Collectively, CCL26 is another agonist for CX3CR1 and may play a dual role in allergic diseases by attracting eosinophils via CCR3 and killer lymphocytes and resident monocytes via CX3CR1.
Hepatitis C Virus Inhibits DNA Damage Repair through Reactive Oxygen and Nitrogen Species and by Interfering with the ATM-NBS1/Mre11/Rad50 DNA Repair Pathway in Monocytes and Hepatocytes
Authors: Machida Keigo , McNamara George , Cheng Kevin T.-H. , Huang Jeffrey , Wang Chun-Hsiang , Comai Lucio , Ou Jing-Hsiung James , Lai Michael M. C. 
Published: October 2010

Abstract
Hepatitis C virus (HCV) infection is associated with the development of hepatocellular carcinoma and putatively also non-Hodgkin’s B cell lymphoma. In this study, we demonstrated that PBMCs obtained from HCV-infected patients showed frequent chromosomal aberrations and that HCV infection of B cells in vitro induced enhanced chromosomal breaks and sister chromatid exchanges. HCV infection hypersensitized cells to ionizing radiation and bleomycin and inhibited nonhomologous end-joining repair. The viral core and nonstructural protein 3 proteins were shown to be responsible for the inhibition of DNA repair, mediated by NO and reactive oxygen species. Stable expression of core protein induced frequent chromosome translocations in cultured cells and in transgenic mice. HCV core protein binds to the NBS1 protein and inhibits the formation of the Mre11/NBS1/Rad50 complex, thereby affecting ATM activation and inhibiting DNA binding of repair enzymes. Taken together, these data indicate that HCV infection inhibits multiple DNA repair processes to potentiate chromosome instability in both monocytes and hepatocytes. These effects may explain the oncogenicity and immunological perturbation of HCV infection.