1,785 research outputs found

    Invasions, DNA barcodes, and rapid biodiversity assessment using ants of Mauritius

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    <p>Abstract</p> <p>Background</p> <p>Using an understudied taxon (Hymenoptera, Formicidae) found on a tropical island (Mauritius) where native flora and fauna have been threatened by 400 years of habitat modification and introduced species, we tested whether estimated incidences of diversity and complementarity were similar when measured by standard morphological alpha-taxonomy or phylogenetic diversity (PD) based on a standardized mitochondrial barcode and corroborating nuclear marker.</p> <p>Results</p> <p>We found that costs related to site loss (considered loss of evolutionary history measured as loss of barcode PD) were not significantly different from predictions made either a) using standard morphology-based taxonomy, or b) measured using a nuclear marker. Integrating morphology and barcode results permitted us to identify a case of initially morphologically-cryptic variation as a new and endemic candidate species. However, barcode estimates of the relative importance of each site or network of sites were dramatically affected when the species in question was known to be indigenous or introduced.</p> <p>Conclusion</p> <p>This study goes beyond a mere demonstration of the rapid gains possible for diversity assessment using a standardized DNA barcode. Contextualization of these gains with ecological and natural history information is necessary to calibrate this wealth of standardized information. Without such an integrative approach, critical opportunities to advance knowledge will be missed.</p

    Pharmacokinetics of Anticoagulant Rodenticides in Target and Non-target Organisms

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    The concentration of a compound at the site of action is a determinant of its toxicity. This principle is affected by a variety of factors including the chemical properties of the compound (pKa, lipophilicity, molecular size), receptor binding affinity, route of exposure, and physiological properties of the organism. Many compounds have to undergo chemical changes, biotransformation, into more toxic or less toxic forms. Because of all of these variables, predicting toxic effects and performing risk assessments of compounds based solely on dose are less accurate than those that include data on absorption, distribution, metabolism (biotransformation), and excretion of the compound. These factors are commonly referred to as ADME. The quantitative study of these properties is called pharmacokinetics and often encompasses the determination of compound concentrations in tissues of interest including blood and the time course of absorption, metabolism, and excretion. A goal of pharmacokinetics is an understanding of the relationship between dose and the concentration of the active compound at the target site. Toxicokinetics is a “unique expansion of pharmacokinetics”, with doses being much greater than those in pharmacokinetic studies (Welling 1995). This is a complicated task, especially for anticoagulant rodenticides (ARs), as exposure (dose) frequently occurs over multiple days and can result from consumption of poisoned animals containing varying concentration of ARs and their metabolites, not simply a toxic bait

    CHIMP: A SIMPLE POPULATION MODEL FOR USE IN INTEGRATED ASSESSMENT OF GLOBAL ENVIRONMENTAL CHANGE

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    We present the Canberra-Hamburg Integrated Model for Population (CHIMP), a new global population model for long-term projections. Distinguishing features of this model, compared to other model for secular population projections, are that (a) mortality, fertility, and migration are partly driven by per capita income; (b) large parts of the model have been estimated rather than calibrated; and (c) the model is in the public domain. Scenario experiments show similarities but also differences with other models. Similarities include rapid aging of the population and an eventual reversal of global population growth. The main difference is that CHIMP projects substantially higher populations, particularly in Africa, primarily because our data indicate a slower fertility decline than assumed elsewhere. Model runs show a strong interaction between population growth and economic growth, and a weak feedback of climate change on population growth.population model, long term projections, global change, integrated assessment

    Epidemiology and potential preventative measures for viral infections in children with malignancy and those undergoing hematopoietic cell transplantation.

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    In pediatric patients with malignancy and those receiving hematopoietic stem cell transplants, bacterial and fungal infections have been the focus of fever and neutropenia episodes for decades. However, improved diagnostic capabilities have revealed viral pathogens as a significant cause of morbidity and mortality. Because of limited effective antiviral therapies, prevention of viral infections is paramount. Pre-exposure and post-exposure prophylaxis and antiviral suppressive therapeutic approaches are reviewed. Additionally, infection control practices specific to this patient population are discussed. A comprehensive approach utilizing each of these can be effective at reducing the negative impact of viral infections

    The DEEP2 Galaxy Redshift Survey: Clustering of Groups and Group Galaxies at z~1

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    We study the clustering properties of groups and of galaxies in groups in the DEEP2 Galaxy Redshift Survey dataset at z~1. Four clustering measures are presented: 1) the group correlation function for 460 groups with estimated velocity dispersions of sigma>200 km/s, 2) the galaxy correlation for the full galaxy sample, using a flux-limited sample of 9800 objects between 0.7<z<1.0, 3) the galaxy correlation for galaxies in groups, and 4) the group-galaxy cross-correlation function. Using the observed number density and clustering amplitude of the groups, the estimated minimum group dark matter halo mass is M_min~6 10^12 h^-1 M_Sun for a flat LCDM cosmology. Groups are more clustered than galaxies, with a relative bias of b=1.7 +/-0.04 on scales r_p=0.5-15 Mpc/h. Galaxies in groups are also more clustered than the full galaxy sample, with a scale-dependent relative bias which falls from b~2.5 +/-0.3 at r_p=0.1 Mpc/h to b~1 +/-0.5 at r_p=10 Mpc/h. The correlation functions for all galaxies and galaxies in groups can be fit by a power-law on scales r_p=0.05-20 Mpc/h. We empirically measure the contribution to the projected correlation function for galaxies in groups from a `one-halo' term and a `two-halo' term by counting pairs of galaxies in the same or in different groups. The projected cross-correlation between shows that red galaxies are more centrally concentrated in groups than blue galaxies at z~1. DEEP2 galaxies in groups appear to have a shallower radial distribution than that of mock galaxy catalogs made from N-body simulations, which assume a central galaxy surrounded by satellite galaxies with an NFW profile. We show that the clustering of galaxies in groups can be used to place tighter constraints on the halo model than can be gained from using the usual galaxy correlation function alone.Comment: 22 pages, 12 figures, in emulateapj format, accepted to ApJ, minor changes made to match published versio

    1D Potts, Yang-Lee Edges and Chaos

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    It is known that the (exact) renormalization transformations for the one-dimensional Ising model in field can be cast in the form of a logistic map f(x) = 4 x (1 - x) with x a function of the Ising couplings. Remarkably, the line bounding the region of chaotic behaviour in x is precisely that defining the Yang-Lee edge singularity in the Ising model. In this paper we show that the one dimensional q-state Potts model for q greater than or equal to 1 also displays such behaviour. A suitable combination of Potts couplings can again be used to define an x satisfying f(x) = 4 x (1 -x). The Yang-Lee zeroes no longer lie on the unit circle in the complex z = exp (h) plane, but their locus is still reproduced by the boundary of the chaotic region in the logistic map.Comment: 6 pages, no figure

    EXPRESS Rack Technology for Space Station

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    The EXPRESS rack provides accommodations for standard Mid-deck Locker and ISIS drawer payloads on the International Space Station. A design overview of the basic EXPRESS rack and two derivatives, the Human Research Facility and the Habitat Holding Rack, is given in Part I. In Part II, the design of the Solid State Power Control Module (SSPCM) is reviewed. The SSPCM is a programmable and remotely controllable power switching and voltage conversion unit which distributes and protects up to 3kW of 12OVDC and 28VDC power to payloads and rack subsystem components. Part III details the development and testing of a new data storage device, the BRP EXPRESS Memory Unit (BEMU). The BEMU is a conduction-cooled device which operates on 28VDC and is based on Boeing-modified 9GB commercial disk-drive technology. In Part IV results of a preliminary design effort for a rack Passive Damping System (PDS) are reported. The PDS is intended to isolate ISPR-based experiment racks from on-orbit vibration. System performance predictions based on component developmental testing indicate that such a system can provide effective isolation at frequencies of 1 Hz and above

    Effect of the dietary supplement Meltdown on catecholamine secretion, markers of lipolysis, and metabolic rate in men and women: a randomized, placebo controlled, cross-over study

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    <p>Abstract</p> <p>Background</p> <p>We have recently reported that the dietary supplement Meltdown<sup>® </sup>increases plasma norepinephrine (NE), epinephrine (EPI), glycerol, free fatty acids (FFA), and metabolic rate in men. However, in that investigation measurements ceased at 90 minutes post ingestion, with values for blood borne variables peaking at this time. It was the purpose of the present investigation to extend the time course of measurement to 6 hours, and to include women within the design to determine if sex differences to treatment exist.</p> <p>Methods</p> <p>Ten men (24 ± 4 yrs) and 10 women (22 ± 2 yrs) ingested Meltdown<sup>® </sup>or a placebo, using a randomized, cross-over design with one week separating conditions. Blood samples were collected immediately before supplementation and at one hour intervals through 6 hours post ingestion. A standard meal was provided after the hour 3 collection. Samples were assayed for EPI, NE, glycerol, and FFA. Five minute breath samples were collected at each time for measurement of metabolic rate and substrate utilization. Area under the curve (AUC) was calculated. Heart rate and blood pressure were recorded at all times. Data were also analyzed using a 2 (sex) × 2 (condition) × 7 (time) repeated measures analysis of variance, with Tukey <it>post hoc </it>testing.</p> <p>Results</p> <p>No sex × condition interactions were noted for AUC for any variable (p > 0.05). Hence, AUC data are collapsed across men and women. AUC was greater for Meltdown<sup>® </sup>compared to placebo for EPI (367 ± 58 pg·mL<sup>-1</sup>·6 hr<sup>-1 </sup>vs. 183 ± 27 pg·mL<sup>-1</sup>·6 hr<sup>-1</sup>; p = 0.01), NE (2345 ± 205 pg·mL<sup>-1</sup>·6 hr<sup>-1 </sup>vs. 1659 ± 184 pg·mL<sup>-1</sup>·6 hr<sup>-1</sup>; p = 0.02), glycerol (79 ± 8 μg·mL<sup>-1</sup>·6 hr<sup>-1 </sup>vs. 59 ± 6 μg·mL<sup>-1</sup>·6 hr<sup>-1</sup>; p = 0.03), FFA (2.46 ± 0.64 mmol·L<sup>-1</sup>·6 hr<sup>-1 </sup>vs. 1.57 ± 0.42 mmol·L<sup>-1</sup>·6 hr<sup>-1</sup>; p = 0.05), and kilocalorie expenditure (439 ± 26 kcal·6 hrs<sup>-1 </sup>vs. 380 ± 14 kcal·6 hrs<sup>-1</sup>; p = 0.02). No effect was noted for substrate utilization (p = 0.39). Both systolic and diastolic blood pressure (p < 0.0001; 1–16 mmHg), as well as heart rate (p = 0.01; 1–9 bpm) were higher for Meltdown<sup>®</sup>. No sex × condition × time interactions were noted for any variable (p > 0.05).</p> <p>Conclusion</p> <p>Ingestion of Meltdown<sup>® </sup>results in an increase in catecholamine secretion, lipolysis, and metabolic rate in young men and women, with a similar response for both sexes. Meltdown<sup>® </sup>may prove to be an effective intervention strategy for fat loss, assuming individuals are normotensive and their treatment is monitored by a qualified health care professional.</p

    The DEEP2 Galaxy Redshift Survey: Color and Luminosity Dependence of Galaxy Clustering at z~1

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    We present measurements of the color and luminosity dependence of galaxy clustering at z~1 in the DEEP2 Galaxy Redshift Survey. Using volume-limited subsamples in bins of both color and luminosity, we find that: 1) The clustering dependence is much stronger with color than with luminosity and is as strong with color at z~1 as is found locally. We find no dependence of the clustering amplitude on color for galaxies on the red sequence, but a significant dependence on color for galaxies within the blue cloud. 2) For galaxies in the range L/L*~0.7-2, a stronger large-scale luminosity dependence is seen for all galaxies than for red and blue galaxies separately. The small-scale clustering amplitude depends significantly on luminosity for blue galaxies, with brighter samples having a stronger rise on scales r_p<0.5 Mpc/h. 3) Redder galaxies exhibit stronger small-scale redshift-space distortions ("fingers of god"), and both red and blue populations show large-scale distortions in xi(r_p,pi) due to coherent infall. 4) While the clustering length, r_0, increases smoothly with galaxy color (in narrow bins), its power-law exponent, gamma, exhibits a sharp jump from the blue cloud to the red sequence. The intermediate color `green' galaxy population likely includes transitional galaxies moving from the blue cloud to the red sequence; on large scales green galaxies are as clustered as red galaxies but show infall kinematics and a small-scale correlation slope akin to the blue galaxy population. 5) We compare our results to a semi-analytic galaxy formation model applied to the Millenium Run simulation. Differences between the data and the model suggest that in the model star formation is shut down too efficiently in satellite galaxies.Comment: 28 pages, 17 figures, emulateapj format, accepted to ApJ, updated to match published versio
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