627 research outputs found

    Paleozoological Data Suggest Euroamerican Settlement Did Not Displace Ursids and North American Elk from Lowlands to Highlands

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    Abstract The hypothesis that Euroamerican settlement displaced some populations of large mammal taxa from lowland plains habitats to previously unoccupied highland mountain habitats was commonly believed in the late nineteenth and early twentieth centuries. By the middle twentieth century biologists had come to favor the hypothesis that Euroamerican colonization resulted in the extirpation of populations of large mammal in lowland habitats and those taxa survived in pre-existing relict populations in the highlands. Why modern biologists changed their minds is unclear. There is no historical evidence that unequivocally favors one hypothesis over the other. The low-elevation Columbia Basin of eastern Washington state in the northwestern United States is surrounded by forested mountains. The majority of historical records (1850 AD or younger) of black bear (Ursus americanus), brown bear (Ursus arctos), and North American elk (Cervus elaphus) occur in mountainous, coniferous forest habitats. Paleozoological records of these taxa B 10,000 year old and[160 year old in both highland and lowland habitats suggest the displacement hypothesis does not apply to ursids and elk in this area. These taxa seem to have been more or less ubiquitous in the area prior to Euroamerican colonization (ca. 1850 AD), and were extirpated from lowland habitats after colonization. Recent colonization of lowland shrub-steppe habitats by elk in particular, although historically unprecedented, must be categorized as recolonization rather than an invasion. Whether a species is classified as indigenous or nonindigenous may influence management activities focused on that species. The paleozoological record indicates ursids and elk are indigenous to the highland forest habitats of eastern Washington

    Response of Chondrocytes to Local Mechanical Injury in an Ex Vivo Model

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    Background:Our goal was to set up an ex vivo culture system to assess whether cartilage wounding (partial-thickness defects) can induce morphological changes in neighboring chondrocytes and whether these cells can translocate to the surface of the defect.Methods:Two-millimeter partial-depth defects were created in human osteochondral explants followed by culture for up to 4 weeks. Frozen sections of defects and defect-free regions were labeled using immunofluorescence for a plasma membrane protein, CD44, and actin with TRITC-phalloidin. Viable nuclei were detected with Hoechst 33342. Differential interference contrast (DIC), confocal, and transmission electron microscopy (TEM) were used to examine process extension.Results:Significant changes in cell morphology occurred in response to wounding in the superficial and deep cartilage zones. These included cell flattening, polarization of the actin cytoskeleton, extension of pseudopods projecting towards the edge of the defect, and interactions of these filopodia with collagen fibers. Cell density decreased progressively in the 300-µm zone adjacent to the defect to an average of approximately 25% to 35% after 3 weeks. Concomitant increases in cell density in the defect margin were observed. By contrast, minimal changes were seen in the middle cartilage zone.Conclusions:These novel observations strongly suggest active cartilage cell responses and movements in response to wounding. It is proposed that cartilage cells use contact guidance on fibrillated collagen to move into and populate defect areas in the superficial and deep zones

    Basic Incompatibilities Between Evolutionary and Behavioral Archaeology

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    Schiffer (1996) recently proposed that, despite some incompatibilities, considerable common ground exists between behavioral archaeology and evolutionary or selectionist, archaeology. He concludes that there is no fundamental reason why the two approaches cannot work in concert to explain human behavioral change. There are, however, several important reasons why the two programs, at least as currently conceived, cannot work together in any thoroughly integrated fashion. Although both programs employ inference, behavioral archaeology conflates the distinct roles of configurational and immanent properties, searches for nomothetic answers to questions about human behavior, overlooks historical contingency when inferring and explaining the nature of past behavior, and in some cases seems to fall back on vitalism as the mechanism of change. Evolutionary archaeology employs immanent properties inferentially, explicitly acknowledges the importance of the historical contingencies of configurational properties, explains human behavior as being time- and spacebound, and calls upon selection and drift (transmission) as the mechanisms of change. Any attempt to integrate the two approaches must begin by addressing these basic differences

    UV continuum emission and diagnostics of hydrogen-containing non-equilibrium plasmas

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    For the first time the emission of the radiative dissociation continuum of the hydrogen molecule (a3Σg+b3Σu+a^{3}\Sigma_{g}^{+} \to b^{3}\Sigma_{u}^{+} electronic transition) is proposed to be used as a source of information for the spectroscopic diagnostics of non-equilibrium plasmas. The detailed analysis of excitation-deactivation kinetics, rate constants of various collisional and radiative transitions and fitting procedures made it possible to develop two new methods of diagnostics of: (1) the ground X1Σg+X^{1}\Sigma_{g}^{+} state vibrational temperature TvibT_{\text{vib}} from the relative intensity distribution, and (2) the rate of electron impact dissociation (d[\mbox{H_{2}}]/dt)_{\text{diss}} from the absolute intensity of the continuum. A known method of determination of TvibT_{\text{vib}} from relative intensities of Fulcher-α\alpha bands was seriously corrected and simplified due to the revision of dad \to a transition probabilities and cross sections of dXd \gets X electron impact excitation. General considerations are illustrated with examples of experiments in pure hydrogen capillary-arc and H2_{2}+Ar microwave discharges.Comment: REVTeX, 25 pages + 12 figures + 9 tables. Phys. Rev. E, eprint replaced because of resubmission to journal after referee's 2nd repor

    Detection of the Power Spectrum of Cosmic Microwave Background Lensing by the Atacama Cosmology Telescope

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    We report the first detection of the gravitational lensing of the cosmic microwave background through a measurement of the four-point correlation function in the temperature maps made by the Atacama Cosmology Telescope. We verify our detection by calculating the levels of potential contaminants and performing a number of null tests. The resulting convergence power spectrum at 2-degree angular scales measures the amplitude of matter density fluctuations on comoving length scales of around 100 Mpc at redshifts around 0.5 to 3. The measured amplitude of the signal agrees with Lambda Cold Dark Matter cosmology predictions. Since the amplitude of the convergence power spectrum scales as the square of the amplitude of the density fluctuations, the 4-sigma detection of the lensing signal measures the amplitude of density fluctuations to 12%.Comment: 4 pages, 4 figures, replaced title and author list with version accepted by Physical Review Letters. Likelihood code can be downloaded from http://bccp.lbl.gov/~sudeep/ACTLensLike.htm

    Molecular characterization of partial-open reading frames 1a and 2 of the human astroviruses in South Korea

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    Human astroviruses (HAstVs) are among the major causes of gastroenteritis in South Korea. In this study, the partial regions of the open reading frame (ORF) 1a and ORF2 genes of HAstVs from gastroenteritis patients in nine hospitals were sequenced, and the molecular characterization of the viruses was revealed. 89 partial nucleotide sequences of ORF1a and 88 partial nucleotide sequences of ORF2 were amplified from 120 stool specimens. Phylogenetic analysis showed that most of the nucleotide sequences of ORF1a and ORF2 were grouped with HAstV type 1 but had evolutionary genetic distance compared with the reference sequences, such as the HAstV-1 prototype, Dresden strain, and Oxford strain. According to the phylogenetic analysis, some nucleotide sequences including SE0506041, SE0506043, and SE0506058, showed the discrepancy of the genotypes, but there was no proof of recombination among the HAstV types. In conclusion, this study showed that the dominant HAstV isolated from the Seoul metropolitan area in 2004-2005 was HAstV type 1, and that Korean HAstV-1 had the genetic distance in evolution compared with the reference sequences of HAstVs. Lots of nucleotide sequences of the ORF1a and ORF2 genes of HAstV will be useful for studying for the control and prevention of HAstV gastroenteritis in South Korea

    Prophylaxis of chemotherapy-induced febrile neutropenia with granulocyte colony-stimulating factors: where are we now?

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    Updated international guidelines published in 2006 have broadened the scope for the use of granulocyte colony-stimulating factor (G-CSF) in supporting delivery of myelosuppressive chemotherapy. G-CSF prophylaxis is now recommended when the overall risk of febrile neutropenia (FN) due to regimen and individual patient factors is ≥20%, for supporting dose-dense and dose-intense chemotherapy and to help maintain dose density where dose reductions have been shown to compromise outcomes. Indeed, there is now a large body of evidence for the efficacy of G-CSFs in supporting dose-dense chemotherapy. Predictive tools that can help target those patients who are most at risk of FN are now becoming available. Recent analyses have shown that, by reducing the risk of FN and chemotherapy dose delays and reductions, G-CSF prophylaxis can potentially enhance survival benefits in patients receiving chemotherapy in curative settings. Accumulating data from ‘real-world’ clinical practice settings indicate that patients often receive abbreviated courses of daily G-CSF and consequently obtain a reduced level of FN protection. A single dose of PEGylated G-CSF (pegfilgrastim) may provide a more effective, as well as a more convenient, alternative to daily G-CSF. Prospective studies are needed to validate the importance of delivering the full dose intensity of standard chemotherapy regimens, with G-CSF support where appropriate, across a range of settings. These studies should also incorporate prospective evaluation of risk stratification for neutropenia and its complications

    Nucleocytoplasmic transport: a thermodynamic mechanism

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    The nuclear pore supports molecular communication between cytoplasm and nucleus in eukaryotic cells. Selective transport of proteins is mediated by soluble receptors, whose regulation by the small GTPase Ran leads to cargo accumulation in, or depletion from the nucleus, i.e., nuclear import or nuclear export. We consider the operation of this transport system by a combined analytical and experimental approach. Provocative predictions of a simple model were tested using cell-free nuclei reconstituted in Xenopus egg extract, a system well suited to quantitative studies. We found that accumulation capacity is limited, so that introduction of one import cargo leads to egress of another. Clearly, the pore per se does not determine transport directionality. Moreover, different cargo reach a similar ratio of nuclear to cytoplasmic concentration in steady-state. The model shows that this ratio should in fact be independent of the receptor-cargo affinity, though kinetics may be strongly influenced. Numerical conservation of the system components highlights a conflict between the observations and the popular concept of transport cycles. We suggest that chemical partitioning provides a framework to understand the capacity to generate concentration gradients by equilibration of the receptor-cargo intermediary.Comment: in press at HFSP Journal, vol 3 16 text pages, 1 table, 4 figures, plus Supplementary Material include

    Incidence, Risk Factors, and Impact of Severe Neutropenia After Hyperthermic Intraperitoneal Mitomycin C

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    Cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC) are considered the standard of care for patients with peritoneal dissemination of appendiceal cancer and are increasingly being evaluated for use in patients with carcinomatosis from colon cancer. Mitomycin C (MMC) is one of the most frequently used HIPEC agents in the management of peritoneal-based gastrointestinal malignancies. This study analyzes the incidence and risk factors for developing neutropenia following MMC-HIPEC combined with CRS. All patients undergoing CRS and MMC-HIPEC for appendiceal cancer between January 1993 and October 2006 were retrospectively reviewed. Logistic regression was used to identify risk factors for the development of neutropenia, defined as an absolute neutrophil count (ANC) <1,000/mm3. One hundred and twenty MMC-HIPEC were performed in 117 patients with appendiceal cancer. The incidence of neutropenia was 39%. Neutropenia occurred in 57.6% of female and 21.3% of male patients (p < 0.0001). Female gender and MMC dose per body surface area (BSA) were independent risk factors for neutropenia on multivariable logistic regression [odds ratio (OR) of neutropenia in females = 3.58 (95% confidence interval, CI: 1.52, 8.43); OR for 5 unit (mg/m2) increase in MMC dose per BSA = 3.37 (95% CI: 1.72, 6.63)]. Neutropenia did not increase the risk of mortality, postoperative infection or length of hospital stay. Neutropenia is a frequent complication associated with MMC-HIPEC. Female sex and MMC dose per BSA are independent risk factors for neutropenia. These differences must be considered in the management of patients undergoing MMC-HIPEC to minimize the toxicity of the procedure
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