2,963 research outputs found

    Avian diversification in the afrotropics

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    Widespread bird species endemic to the lowlands of the Guineo-Congolian rainforest of Africa have traditionally been thought to lack substantial intraspecific structure. This view owes largely to their widespread distributions coupled with the absence of discrete geographic variation in plumage. In the following chapters I examine the phylogeographic patterns of three such species using a combination of molecular and morphometric data. The three species investigated are the Green Hylia (Hylia prasina), the Red-tailed Bristlebill (Bleda syndactylus), and the Yellow-whiskered Greenbul (Andropadus latirostris). Using the phylogeographic patterns from these data, I assess 1) models of rainforest species diversification, 2) current taxonomy, and 3) implications for conservation of lowland rainforests. In contrast to the lack of discrete plumage variation in these species, phylogeographic analyses reveal a high degree molecular and morphological divergence. Furthermore, general patterns of geographical structure of the mtDNA data are largely congruent among the three species. Each species has unique mtDNA haplotype groups in Liberia, Ghana, Cameroon-Gabon, Central African Republic, and the eastern Democratic Republic of Congo. Andropadus latirostris, which also occurs in montane forests, has unique haplotype groups in these montane regions. Taken together the patterns of geographic variation in molecular and morphological datasets from these three species suggest a history of allopatric divergence via genetic drift, consistent with predictions of refugial diversification. There is also some evidence for a potential role for divergent selection along a longitudinal temperature gradient in shaping the morphometric diversity in Andropadus latirostris. Despite their widespread distributions and the potential for high gene flow, these three species exhibit a remarkable level of geographic structure across the lowland rainforest. This contradicts the prevailing view of widespread lowland species as large panmictic populations. This significant geographic structure has important implications for species and habitat conservation in Africa, where lowland forest is typically viewed as a continuous block of homogeneous habitat. The implication is habitat loss in one area would not result in a substantial loss of biodiversity because many of the species are widely distributed. The geographic structure evident in these data suggests that that is not the case

    Detection of Low Frequency Multi-Drug Resistance and Novel Putative Maribavir Resistance in Immunocompromised Pediatric Patients with Cytomegalovirus.

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    Human cytomegalovirus (HCMV) is a significant pathogen in immunocompromised individuals, with the potential to cause fatal pneumonitis and colitis, as well as increasing the risk of organ rejection in transplant patients. With the advent of new anti-HCMV drugs there is therefore considerable interest in using virus sequence data to monitor emerging resistance to antiviral drugs in HCMV viraemia and disease, including the identification of putative new mutations. We used target-enrichment to deep sequence HCMV DNA from 11 immunosuppressed pediatric patients receiving single or combination anti-HCMV treatment, serially sampled over 1-27 weeks. Changes in consensus sequence and resistance mutations were analyzed for three ORFs targeted by anti-HCMV drugs and the frequencies of drug resistance mutations monitored. Targeted-enriched sequencing of clinical material detected mutations occurring at frequencies of 2%. Seven patients showed no evidence of drug resistance mutations. Four patients developed drug resistance mutations a mean of 16 weeks after starting treatment. In two patients, multiple resistance mutations accumulated at frequencies of 20% or less, including putative maribavir and ganciclovir resistance mutations P522Q (UL54) and C480F (UL97). In one patient, resistance was detected 14 days earlier than by PCR. Phylogenetic analysis suggested recombination or superinfection in one patient. Deep sequencing of HCMV enriched from clinical samples excluded resistance in 7 of 11 subjects and identified resistance mutations earlier than conventional PCR-based resistance testing in 2 patients. Detection of multiple low level resistance mutations was associated with poor outcome

    A New Species of Boubou (Malaconotidae: Laniarius) from the Albertine Rift

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    We describe Laniarius willardi, a new species of boubou shrike (Malaconotidae) from the Albertine Rift of Africa. The most conspicuous, distinguishing morphological feature of the species is a gray to blue-gray iris. This and external morphometric data indicate that L. willardi is diagnosable from other black or sooty boubous. Further, L. willardi is genetically diagnosable, and its closest relative is the Mountain Sooty Boubou (L. poensis camerunensis) from Cameroon. The Crimson-breasted Bush-shrike (L. atrococcineus) and the Lowland Sooty Boubou (L. leucorhynchus) are together the sister clade to L. willardi—L.p. camerunensis. Laniarius willardi and the geographically codistributed L. p. holomelas differ by 11.5% in uncorrected sequence divergence, and elevational data taken from museum specimens suggest the possibility of elevational segregation of the species at ∼2,000 m, withL. willardi occurring at lower elevations. Our broad sampling of black and sooty boubou taxa indicate that (1) races of Mountain Sooty Boubou (L. poensis) do not form a monophyletic clade; (2) L. p. camerunensismay represent multiple, nonsister lineages; and (3) at least one race of Fülleborn\u27s Black Boubou (L. fuelleborni usambaricus) is genetically distinct from other races of that species

    Sex differences in mathematics and reading achievement are inversely related: within- and across-nation assessment of 10 years of PISA data

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    We analyzed one decade of data collected by the Programme for International Student Assessment (PISA), including the mathematics and reading performance of nearly 1.5 million 15 year olds in 75 countries. Across nations, boys scored higher than girls in mathematics, but lower than girls in reading. The sex difference in reading was three times as large as in mathematics. There was considerable variation in the extent of the sex differences between nations. There are countries without a sex difference in mathematics performance, and in some countries girls scored higher than boys. Boys scored lower in reading in all nations in all four PISA assessments (2000, 2003, 2006, 2009). Contrary to several previous studies, we found no evidence that the sex differences were related to nations’ gender equality indicators. Further, paradoxically, sex differences in mathematics were consistently and strongly inversely correlated with sex differences in reading: Countries with a smaller sex difference in mathematics had a larger sex difference in reading and vice versa. We demonstrate that this was not merely a between-nation, but also a within-nation effect. This effect is related to relative changes in these sex differences across the performance continuum: We did not find a sex difference in mathematics among the lowest performing students, but this is where the sex difference in reading was largest. In contrast, the sex difference in mathematics was largest among the higher performing students, and this is where the sex difference in reading was smallest. The implication is that if policy makers decide that changes in these sex differences are desired, different approaches will be needed to achieve this for reading and mathematics. Interventions that focus on high-achieving girls in mathematics and on low achieving boys in reading are likely to yield the strongest educational benefits

    Sr-Nd-Pb-Hf isotope results from ODP Leg 187: Evidence for mantle dynamics of the Australian-Antarctic Discordance and origin of the Indian MORB source

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    New high precision PIMMS Hf and Pb isotope data for 14–28 Ma basalts recovered during ODP Leg 187 are compared with zero-age dredge samples from the Australian-Antarctic Discordance (AAD). These new data show that combined Nd-Hf isotope systematics can be used as an effective discriminant between Indian and Pacific MORB source mantle domains. In particular, Indian mantle is displaced to lower εNd and higher εHf ratios compared to Pacific mantle. As with Pb isotope plots, there is almost no overlap between the two mantle types in Nd-Hf isotope space. On the basis of our new Nd-Hf isotope data, we demonstrate that Pacific MORB-source mantle was present near the eastern margin of the AAD from as early as 28 Ma, its boundary with Indian MORB-source mantle coinciding with the eastern edge of a basin-wide arcuate depth anomaly that is centered on the AAD. This observation rules out models requiring rapid migration of Pacific MORB mantle into the Indian Ocean basin since separation of Australia from Antarctica. Although temporal variations in isotopic composition can be discerned relative to the fracture zone boundary of the modern AAD at 127°E, the distribution of different compositional groups appears to have remained much the same relative to the position of the residual depth anomaly for the past 30 m.y. Thus significant lateral flow of mantle along the ridge axis toward the interface appears unlikely. Instead, the dynamics that maintain both the residual depth anomaly and the isotopic boundary between Indian and Pacific mantle are due to eastward migration of the Australian and Antarctic plates over a stagnated, but slowly upwelling, slab oriented roughly orthogonal to the ridge axis. Temporal and spatial variations in the compositions of Indian MORB basalts within the AAD can be explained by progressive displacement of shallower Indian MORB-source mantle by deeper mantle having a higher εHf composition ascending ahead of the upwelling slab. Models for the origin of the distinctive composition of the Indian MORB-source based on recycling of a heterogeneous enriched component that consist of ancient altered ocean crust plus<10% pelagic sediment are inconsistent with Nd-Hf isotope systematics. Instead, the data can be explained by a model in which Indian mantle includes a significant proportion of material that was processed in the mantle wedge above a subduction zone and was subsequently mixed back into unprocessed upper mantle

    The UK kidney donor risk index poorly predicts long-term transplant survival in paediatric kidney transplant recipients

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    BackgroundThe UK kidney offering scheme introduced a kidney donor risk index (UK-KDRI) to improve the utility of deceased-donor kidney allocations. The UK-KDRI was derived using adult donor and recipient data. We assessed this in a paediatric cohort from the UK transplant registry.MethodsWe performed Cox survival analysis on first kidney-only deceased brain-dead transplants in paediatric (&lt;18 years) recipients from 2000-2014. The primary outcome was death-censored allograft survival &gt;30 days post-transplant. The main study variable was UK-KDRI derived from seven donor risk-factors, categorised into four groups (D1-low risk, D2, D3 and D4-highest risk). Follow-up ended on 31-December-2021.Results319/908 patients experienced transplant loss with rejection as the main cause (55%). The majority of paediatric patients received donors from D1 donors (64%). There was an increase in D2-4 donors during the study period, whilst the level of HLA mismatching improved. The KDRI was not associated with allograft failure. In multi-variate analysis, increasing recipient age [adjusted HR and 95%CI: 1.05(1.03-1.08) per-year, p&lt;0.001], recipient minority ethnic group [1.28(1.01-1.63), p&lt;0.05), dialysis before transplant [1.38(1.04-1.81), p&lt;0.005], donor height [0.99 (0.98-1.00) per centimetre, p&lt;0.05] and level of HLA mismatch [Level 3: 1.92(1.19-3.11); Level 4: 2.40(1.26-4.58) versus Level 1, p&lt;0.01] were associated with worse outcomes. Patients with Level 1 and 2 HLA mismatches (0 DR +0/1 B mismatch) had median graft survival &gt;17 years regardless of UK-KDRI groups. Increasing donor age was marginally associated with worse allograft survival [1.01 (1.00-1.01) per year, p=0.05].SummaryAdult donor risk scores were not associated with long-term allograft survival in paediatric patients. The level of HLA mismatch had the most profound effect on survival. Risk models based on adult data alone may not have the same validity for paediatric patients and therefore all age-groups should be included in future risk prediction models

    Deep Underground Science and Engineering Laboratory - Preliminary Design Report

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    The DUSEL Project has produced the Preliminary Design of the Deep Underground Science and Engineering Laboratory (DUSEL) at the rehabilitated former Homestake mine in South Dakota. The Facility design calls for, on the surface, two new buildings - one a visitor and education center, the other an experiment assembly hall - and multiple repurposed existing buildings. To support underground research activities, the design includes two laboratory modules and additional spaces at a level 4,850 feet underground for physics, biology, engineering, and Earth science experiments. On the same level, the design includes a Department of Energy-shepherded Large Cavity supporting the Long Baseline Neutrino Experiment. At the 7,400-feet level, the design incorporates one laboratory module and additional spaces for physics and Earth science efforts. With input from some 25 science and engineering collaborations, the Project has designed critical experimental space and infrastructure needs, including space for a suite of multidisciplinary experiments in a laboratory whose projected life span is at least 30 years. From these experiments, a critical suite of experiments is outlined, whose construction will be funded along with the facility. The Facility design permits expansion and evolution, as may be driven by future science requirements, and enables participation by other agencies. The design leverages South Dakota's substantial investment in facility infrastructure, risk retirement, and operation of its Sanford Laboratory at Homestake. The Project is planning education and outreach programs, and has initiated efforts to establish regional partnerships with underserved populations - regional American Indian and rural populations

    A pragmatic, open-label, randomized controlled trial of Plasma-Lyte-148 versus standard intravenous fluids in children receiving kidney transplants (PLUTO)

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    Acute electrolyte and acid-base imbalance is experienced by many children following kidney transplant. This is partly because doctors give very large volumes of artificial fluids to keep the new kidney working. When severe, fluid imbalance can lead to seizures, cerebral edema and death. In this pragmatic, open-label, randomized controlled trial, we randomly assigned (1:1) pediatric kidney transplant recipients to Plasma-Lyte-148 or standard of care perioperative intravenous fluids (predominantly 0.45% sodium chloride and 0.9% sodium chloride solutions). We then compared clinically significant electrolyte and acid-base abnormalities in the first 72 hours post-transplant. The primary outcome, acute hyponatremia, was experienced by 53% of 68 participants in the Plasma-Lyte-148 group and 58% of 69 participants in the standard fluids group (odds ratio 0·77 (0·34 - 1·75)). Five of 16 secondary outcomes differed with Plasma-Lyte-148: hypernatremia was significantly more frequent (odds ratio 3·5 (1·1 - 10·8)), significantly fewer changes to fluid prescriptions were made (rate ratio 0·52 (0·40-0·67)), and significantly fewer participants experienced hyperchloremia (odds ratio 0·17 (0·07 - 0·40)), acidosis (odds ratio 0·09 (0·04 - 0·22)) and hypomagnesemia (odds ratio 0·21 (0·08 - 0·50)). No other secondary outcomes differed between groups. Serious adverse events were reported in 9% of participants randomized to Plasma-Lyte-148 and 7% of participants randomized to standard fluids. Thus, perioperative Plasma-Lyte-148 did not change the proportion of children who experienced acute hyponatremia compared to standard fluids. However fewer fluid prescription changes were made with Plasma-Lyte-148, while hyperchloremia and acidosis were less common

    Cross Sections for the Reactions e+e- --> K+ K- pi+pi-, K+ K- pi0pi0, and K+ K- K+ K- Measured Using Initial-State Radiation Events

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    We study the processes e+e- --> K+ K- pi+pi-gamma, K+ K- pi0pi0gamma, and K+ K- K+ K-gamma, where the photon is radiated from the initial state. About 84000, 8000, and 4200 fully reconstructed events, respectively, are selected from 454 fb-1 of BaBar data. The invariant mass of the hadronic final state defines the \epem center-of-mass energy, so that the K+ K- pi+pi- data can be compared with direct measurements of the e+e- --> K+ K- pi+pi- reaction. No direct measurements exist for the e+e- --> K+ K-pi0pi0 or e+e- --> K+ K-K+ K- reactions, and we present an update of our previous result with doubled statistics. Studying the structure of these events, we find contributions from a number of intermediate states, and extract their cross sections. In particular, we perform a more detailed study of the e+e- --> phi(1020)pipigamma reaction, and confirm the presence of the Y(2175) resonance in the phi(1020) f0(980) and K+K-f0(980) modes. In the charmonium region, we observe the J/psi in all three final states and in several intermediate states, as well as the psi(2S) in some modes, and measure the corresponding product of branching fraction and electron width.Comment: 35 pages, 42 figure

    Study of Upsilon(3S,2S) -> eta Upsilon(1S) and Upsilon(3S,2S) -> pi+pi- Upsilon(1S) hadronic trasitions

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    We study the Upsilon(3S,2S)->eta Upsilon(1S) and Upsilon(3S,2S)->pi+pi- Upsilon(1S) transitions with 122 million Upsilon(3S) and 100 million Upsilon(2S) mesons collected by the BaBar detector at the PEP-II asymmetric energy e+e- collider. We measure B[Upsilon(2S)->eta Upsilon(1S)]=(2.39+/-0.31(stat.)+/-0.14(syst.))10^-4 and Gamma[Upsilon(2S)->eta Upsilon(1S)]/Gamma[Upsilon(2S)-> pi+pi- Upsilon(1S)]=(1.35+/-0.17(stat.)+/-0.08(syst.))10^-3. We find no evidence for Upsilon(3S)->eta Upsilon(1S) and obtain B[Upsilon(3S)->eta Upsilon(1S)]<1.0 10^-4 and Gamma[Upsilon(3S)->eta Upsilon(1S)]/Gamma[Upsilon(3S)->pi+pi- Upsilon(1S)]<2.3 10^-3 as upper limits at the 90% confidence level. We also provide improved measurements of the Upsilon(2S) - Upsilon(1S) and Upsilon(3S) - Upsilon(1S) mass differences, 562.170+/-0.007(stat.)+/-0.088(syst.) MeV/c^2 and 893.813+/-0.015(stat.)+/-0.107(syst.) MeV/c^2 respectively.Comment: 8 pages, 16 encapsulated postscript figures, submitted to Phys.Rev.
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