2,573 research outputs found

    History and Fall Migration of Northern Saw-Whet Owls (Aegolius acadicus) in Arkansas

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    The secretive Northern Saw-whet Owl (Aegolius acadicus) is believed to be much more widespread during fall and winter than previously thought in the southern United States. To see if they occur more frequently in Arkansas, we initiated a banding study in fall of 2014 in northwestern Arkansas. Prior to that, only 12 historic records existed for Arkansas between 1959 and 2010. Over the course of two field seasons, we captured and banded 24 Northern Saw-whet Owls in rural Madison County. All birds were mist-netted along a trail, in woodland composed of pine and cedar with fairly dense undergrowth. Two were captured during our 2014 season when we started in late November and 22 were captured between late October and early December in 2015. We also had at least 10 birds vocalizing at our site. It would appear that the peak of migration in Arkansas is late October through early November, with capture rates dropping off by early December. All but one of the captured birds were females, the most common sex this far south. There was a fairly even distribution of hatch-year, second year, and after-second-year birds and hatch-year birds and adults arrived at about the same time in late October and early November in 2015. Exactly where the owls are migrating from is unknown, although three foreign recoveries in Missouri and four recoveries in Arkansas suggest they are coming from the western Great Lakes region. Once considered a vagrant, based on our research, the Northern Saw-whet Owl appears to be an uncommon fall migrant, at least in the northwestern part of Arkansas. Comparing our data with that for central Missouri, about the same number of birds were captured at the same rates for about the same length of time, suggesting that Northern Saw-whet Owls are probably more common in the Ozarks than previously thought

    NCBI Reference Sequences (RefSeq): current status, new features and genome annotation policy

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    The National Center for Biotechnology Information (NCBI) Reference Sequence (RefSeq) database is a collection of genomic, transcript and protein sequence records. These records are selected and curated from public sequence archives and represent a significant reduction in redundancy compared to the volume of data archived by the International Nucleotide Sequence Database Collaboration. The database includes over 16 000 organisms, 2.4 × 106 genomic records, 13 × 106 proteins and 2 × 106 RNA records spanning prokaryotes, eukaryotes and viruses (RefSeq release 49, September 2011). The RefSeq database is maintained by a combined approach of automated analyses, collaboration and manual curation to generate an up-to-date representation of the sequence, its features, names and cross-links to related sources of information. We report here on recent growth, the status of curating the human RefSeq data set, more extensive feature annotation and current policy for eukaryotic genome annotation via the NCBI annotation pipeline. More information about the resource is available online (see http://www.ncbi.nlm.nih.gov/RefSeq/)

    Bilateral negotiation in a multi-agent supply chain system

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    A supply chain is a set of organizations directly linked by flows of services from suppliers to customers. Supply chain activities range from the ordering and receipt of raw materials to the production and distribution of finished goods. Supply chain management is the integration of key activities across a supply chain for the purposes of building competitive infrastructures, synchronizing supply with demand, and leveraging worldwide logistics. This paper addresses the challenges created by supply chain management towards improving long-term performance of companies. It presents a multi-agent supply chain system composed of multiple software agents, each responsible for one or more supply chain activities, and each interacting with other agents in the execution of their responsibilities. Additionally, this paper presents the key features of a negotiation model for software agents. The model handles bilateral multi-issue negotiation and incorporates an alternating offers protocol, a set of logrolling strategies, and a set of negotiation tactics

    Raf-independent Deregulation of p38 and JNK Mitogen-activated Protein Kinases Are Critical for Ras Transformation

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    Activated Ras, but not Raf, causes transformation of RIE-1 epithelial cells, supporting the importance of Raf-independent pathways in mediating Ras transformation. The p38 and JNK mitogen-activated protein kinase cascades are activated by Ras via Raf-independent effector function. Therefore, we determined whether p38 and JNK activation are involved in Ras transformation of RIE-1 epithelial cells. Rather surprisingly, we found that pharmacologic inhibition of p38, together with Raf activation of ERK, was sufficient to mimic the morphologic and growth transformation caused by oncogenic Ras. p38 inhibition together with ERK activation also caused the same alterations in cyclin D1 and p21(CIP1) expression caused by Ras and induced an autocrine growth factor loop important for transformation. Finally, in contrast to p38, we found that JNK activation promoted Ras transformation, and that Ras deregulation of p38 and JNK was not mediated by activation of the Rac small GTPase. We conclude that a key action of Raf-independent effector pathways important for Ras transformation may involve inhibition of p38 and activation of JNK

    An analysis of integrative outcomes in the Dayton peace negotiations

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    The nature of the negotiated outcomes of the eight issues of the Dayton Peace Agreement was studied in terms of their integrative and distributive aspects. in cases where integrative elements were Sound, further analysis was conducted by concentrating on Pruitt's five types of integrative solutions: expanding the pie, cost cutting, non-specific compensation, logrolling, and bridging. The results showed that real world international negotiations can arrive at integrative agreements even when they involve redistribution of resources tin this case the redistribution of former Yugoslavia). Another conclusion was that an agreement can consist of several distributive outcomes and several integrative outcomes produced by different kinds of mechanisms. Similarly, in single issues more than one mechanism can be used simultaneously. Some distributive bargaining was needed in order to determine how much compensation was required. Finally, each integrative formula had some distributive aspects as well

    DNA replication stress restricts ribosomal DNA copy number

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    Ribosomal RNAs (rRNAs) in budding yeast are encoded by ~100–200 repeats of a 9.1kb sequence arranged in tandem on chromosome XII, the ribosomal DNA (rDNA) locus. Copy number of rDNA repeat units in eukaryotic cells is maintained far in excess of the requirement for ribosome biogenesis. Despite the importance of the repeats for both ribosomal and non-ribosomal functions, it is currently not known how “normal” copy number is determined or maintained. To identify essential genes involved in the maintenance of rDNA copy number, we developed a droplet digital PCR based assay to measure rDNA copy number in yeast and used it to screen a yeast conditional temperature-sensitive mutant collection of essential genes. Our screen revealed that low rDNA copy number is associated with compromised DNA replication. Further, subculturing yeast under two separate conditions of DNA replication stress selected for a contraction of the rDNA array independent of the replication fork blocking protein, Fob1. Interestingly, cells with a contracted array grew better than their counterparts with normal copy number under conditions of DNA replication stress. Our data indicate that DNA replication stresses select for a smaller rDNA array. We speculate that this liberates scarce replication factors for use by the rest of the genome, which in turn helps cells complete DNA replication and continue to propagate. Interestingly, tumors from mini chromosome maintenance 2 (MCM2)-deficient mice also show a loss of rDNA repeats. Our data suggest that a reduction in rDNA copy number may indicate a history of DNA replication stress, and that rDNA array size could serve as a diagnostic marker for replication stress. Taken together, these data begin to suggest the selective pressures that combine to yield a “normal” rDNA copy number

    Expression Patterns of Duplicate Tryptophan Synthase [beta] Genes in Arabidopsis thaliana

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    On Determining Dead Layer and Detector Thicknesses for a Position-Sensitive Silicon Detector

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    In this work, two particular properties of the position-sensitive, thick silicon detectors (known as the "E" detectors) in the High Resolution Array (HiRA) are investigated: the thickness of the dead layer on the front of the detector, and the overall thickness of the detector itself. The dead layer thickness for each E detector in HiRA is extracted using a measurement of alpha particles emitted from a 212^{212}Pb pin source placed close to the detector surface. This procedure also allows for energy calibrations of the E detectors, which are otherwise inaccessible for alpha source calibration as each one is sandwiched between two other detectors. The E detector thickness is obtained from a combination of elastically scattered protons and an energy-loss calculation method. Results from these analyses agree with values provided by the manufacturer.Comment: Accepted for publication in Nuclear Instruments and Methods in Physics Researc

    Convergence of the all-time supremum of a L\'evy process in the heavy-traffic regime

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    In this paper we derive a technique of obtaining limit theorems for suprema of L\'evy processes from their random walk counterparts. For each a>0a>0, let {Yn(a):n1}\{Y^{(a)}_n:n\ge 1\} be a sequence of independent and identically distributed random variables and {Xt(a):t0}\{X^{(a)}_t:t\ge 0\} be a L\'evy processes such that X1(a)=dY1(a)X_1^{(a)}\stackrel{d}{=} Y_1^{(a)}, EX1(a)<0\mathbb E X_1^{(a)}<0 and EX1(a)0\mathbb E X_1^{(a)}\uparrow0 as a0a\downarrow0. Let Sn(a)=k=1nYk(a)S^{(a)}_n=\sum_{k=1}^n Y^{(a)}_k. Then, under some mild assumptions, Δ(a)maxn0Sn(a)dR    Δ(a)supt0Xt(a)dR\Delta(a)\max_{n\ge 0} S_n^{(a)}\stackrel{d}{\to} R\iff\Delta(a)\sup_{t\ge 0} X^{(a)}_t\stackrel{d}{\to} R, for some random variable RR and some function Δ()\Delta(\cdot). We utilize this result to present a number of limit theorems for suprema of L\'evy processes in the heavy-traffic regime
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