2,016 research outputs found

    Preliminary examination of the Yamato-86032 lunar meteorite: II. Major and trace element chemistry

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    The chemical composition of the new lunar meteorite Yamato-86032 has been studied by several laboratories in a consortium study. A preliminary report on the first analytical results from seven laboratories is given in this paper. The meteorite, which is the largest lunar meteorite recovered so far, is more heavily shocked than the other five lunar meteorites, which makes it difficult to classify the rock exactly. Although it may be classified as an anorthositic breccia the trace element composition of Y-86032 is somewhat different from the composition of the other known lunar meteorites. The major element chemistry of Y-86032 is similar to the other lunar meteorites, except for the iron content, which is lower by a factor of about 1. 4. Since the magnesium abundance is nearly identical there is a disparity in the mg ratio. The REE abundances in Y-86032 are very low and comparable to Y-82192/3. There is no evidence of any KREEP component. The abundances of several lithophile and incompatible elements are lower in Y-86032 than in the other lunar meteorites. The siderophile element contents are low and vary between individual chips. Sc, Cr, Mn, and Co have significantly lower abundances than in Y-82192/3. The chemical investigations demonstrate that Y-86032 is a new and important sample from the lunar highlands

    Spectroscopy of neutron-unbound 27,28^{27,28}F

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    The ground state of 28^{28}F has been observed as an unbound resonance 2202\underline{2}0 keV above the ground state of 27^{27}F. Comparison of this result with USDA/USDB shell model predictions leads to the conclusion that the 28^{28}F ground state is primarily dominated by sdsd-shell configurations. Here we present a detailed report on the experiment in which the ground state resonance of 28^{28}F was first observed. Additionally, we report the first observation of a neutron-unbound excited state in 27^{27}F at an excitation energy of 2500(220)25\underline{0}0 (2\underline{2}0) keV.Comment: 10 pages, 11 figures, Accepted for publication in Phys. Rev.

    Rewiring of Aminoacyl-tRNA Synthetase Localization and Interactions in Plants With Extensive Mitochondrial tRNA Gene Loss

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    The number of tRNAs encoded in plant mitochondrial genomes varies considerably. Ongoing loss of bacterial-like mitochondrial tRNA genes in many lineages necessitates the import of nuclear-encoded counterparts that share little sequence similarity. Because tRNAs are involved in highly specific molecular interactions, this replacement process raises questions about the identity and trafficking of enzymes necessary for the maturation and function of newly imported tRNAs. In particular, the aminoacyl-tRNA synthetases (aaRSs) that charge tRNAs are usually divided into distinct classes that specialize on either organellar (mitochondrial and plastid) or nuclear-encoded (cytosolic) tRNAs. Here, we investigate the evolution of aaRS subcellular localization in a plant lineage (Sileneae) that has experienced extensive and rapid mitochondrial tRNA loss. By analyzing full-length mRNA transcripts (PacBio Iso-Seq), we found predicted retargeting of many ancestrally cytosolic aaRSs to the mitochondrion and confirmed these results with colocalization microscopy assays. However, we also found cases where aaRS localization does not appear to change despite functional tRNA replacement, suggesting evolution of novel interactions and charging relationships. Therefore, the history of repeated tRNA replacement in Sileneae mitochondria reveals that differing constraints on tRNA/aaRS interactions may determine which of these alternative coevolutionary paths is used to maintain organellar translation in plant cells

    Exploring the Low-ZZ Shore of the Island of Inversion at N=19N = 19

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    The technique of invariant mass spectroscopy has been used to measure, for the first time, the ground state energy of neutron-unbound 28F,^{28}\textrm{F}, determined to be a resonance in the 27F+n^{27}\textrm{F} + n continuum at 220(50)2\underline{2}0 (\underline{5}0) keV. States in 28F^{28}\textrm{F} were populated by the reactions of a 62 MeV/u 29Ne^{29}\textrm{Ne} beam impinging on a 288 mg/cm2\textrm{mg/cm}^2 beryllium target. The measured 28F^{28}\textrm{F} ground state energy is in good agreement with USDA/USDB shell model predictions, indicating that pfpf shell intruder configurations play only a small role in the ground state structure of 28F^{28}\textrm{F} and establishing a low-ZZ boundary of the island of inversion for N=19 isotones.Comment: 5 pages, 4 figures, to be published in Phys. Rev. Let

    Independent large scale duplications in multiple M. tuberculosis lineages overlapping the same genomic region

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    Mycobacterium tuberculosis, the causative agent of most human tuberculosis, infects one third of the world's population and kills an estimated 1.7 million people a year. With the world-wide emergence of drug resistance, and the finding of more functional genetic diversity than previously expected, there is a renewed interest in understanding the forces driving genome evolution of this important pathogen. Genetic diversity in M. tuberculosis is dominated by single nucleotide polymorphisms and small scale gene deletion, with little or no evidence for large scale genome rearrangements seen in other bacteria. Recently, a single report described a large scale genome duplication that was suggested to be specific to the Beijing lineage. We report here multiple independent large-scale duplications of the same genomic region of M. tuberculosis detected through whole-genome sequencing. The duplications occur in strains belonging to both M. tuberculosis lineage 2 and 4, and are thus not limited to Beijing strains. The duplications occur in both drug-resistant and drug susceptible strains. The duplicated regions also have substantially different boundaries in different strains, indicating different originating duplication events. We further identify a smaller segmental duplication of a different genomic region of a lab strain of H37Rv. The presence of multiple independent duplications of the same genomic region suggests either instability in this region, a selective advantage conferred by the duplication, or both. The identified duplications suggest that large-scale gene duplication may be more common in M. tuberculosis than previously considere

    An Integrated Approach to Weather Radar Calibration and Monitoring Using Ground Clutter and Satellite Comparisons

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    The stability and accuracy of weather radar reflectivity calibration are imperative for quantitative applications, such as rainfall estimation, severe weather monitoring and nowcasting, and assimilation in numerical weather prediction models. Various radar calibration and monitoring techniques have been developed, but only recently have integrated approaches been proposed, that is, using different calibration techniques in combination. In this paper the following three techniques are used: 1) ground clutter monitoring, 2) comparisons with spaceborne radars, and 3) the self-consistency of polarimetric variables. These techniques are applied to a C-band polarimetric radar (CPOL) located in the Australian tropics since 1998. The ground clutter monitoring technique is applied to each radar volumetric scan and provides a means to reliably detect changes in calibration, relative to a baseline. It is remarkably stable to within a standard deviation of 0.1 dB (decibels). To obtain an absolute calibration value, CPOL observations are compared to spaceborne radars on board TRMM (Tropical Rainfall Measuring Mission) and GPM (Global Precipitation Measurement) using a volume-matching technique. Using an iterative procedure and stable calibration periods identified by the ground echoes technique, we improve the accuracy of this technique to about 1 dB. Finally, we review the self-consistency technique and constrain its assumptions using results from the hybrid TRMM-GPM and ground echo technique. Small changes in the self-consistency parameterization can lead to 5 dB of variation in the reflectivity calibration. We find that the drop-shape model of Brandes et al. with a standard deviation of the canting angle of 12 degrees best matches our dataset

    Sexual Practices, Drug Use Behaviors, and Prevalence of HIV, Syphilis, Hepatitis B and C, and HTLV-1/2 in Immigrant and Non-immigrant Female Sex Workers in Argentina

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    Objective To study socio-demographics, sexual practices, drug use behaviors, and prevalences of HIV, syphilis, hepatitis B and C, HTLV-1 and HTLV-2 in immigrant (foreigner) and non-immigrant (local/native) female sex workers (FSW). Design This was a cross-sectional study in immigrant and non-immigrant FSW living in Buenos Aires, Argentina. Participants were interviewed using a standardized questionnaire. Results A total of 625 FSW were enrolled, of whom 169 (27%) were immigrant FSW from Paraguay, the Dominican Republic, Brazil, Peru, and Uruguay. The prevalence of syphilis and hepatitis C was significantly higher among Argentinean FSW than among immigrant FSW. However, hepatitis B prevalence was higher among immigrant FSW. Adjusted risk factor analysis comparing immigrant FSW with Argentinean FSW indicated that marital status (single), occupation (none), fee per sex act (≤US$7), workplace (bar and cabaret), and anal sex with clients were significantly associated with immigrant FSW status. Conclusions Effective HIV/STI prevention and medical care programs need to be tailored to the specific needs of both FSW groups in Argentina.Fil: Bautista, Christian T.. Walter Reed Army Institute of Research; Estados Unidos. US Naval Medical Research Center Detachment; Estados UnidosFil: Pando, María de los Ángeles. Universidad de Buenos Aires. Facultad de Medicina. Departamento de Microbiología. Centro Nacional de Referencia para el Sida; Argentina. University of Maryland; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay; ArgentinaFil: Reynaga, Elena. Asociación de Mujeres Meretrices de Argentina; ArgentinaFil: Marone, Ruben. NEXO; ArgentinaFil: Sateren, Warren B.. Walter Reed Army Institute of Research; Estados UnidosFil: Montano, Silvia M.. US Naval Medical Research Center Detachment; Estados UnidosFil: Sanchez, Jose L.. US Naval Medical Research Center Detachment; Estados Unidos. Walter Reed Army Institute of Research; Estados UnidosFil: Ávila, María Mercedes. Universidad de Buenos Aires. Facultad de Medicina. Departamento de Microbiología. Centro Nacional de Referencia para el Sida; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay; Argentin

    Roll, Roll, Roll your Root:A Comprehensive Analysis of the First Ever DNSSEC Root KSK Rollover

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    The DNS Security Extensions (DNSSEC) add authenticity and integrity to the naming system of the Internet. Resolvers that validate information in the DNS need to know the cryptographic public key used to sign the root zone of the DNS. Eight years after its introduction and one year after the originally scheduled date, this key was replaced by ICANN for the first time in October 2018. ICANN considered this event, called a rollover, "an overwhelming success" and during the rollover they detected "no significant outages". In this paper, we independently follow the process of the rollover starting from the events that led to its postponement in 2017 until the removal of the old key in 2019. We collected data from multiple vantage points in the DNS ecosystem for the entire duration of the rollover process. Using this data, we study key events of the rollover. These events include telemetry signals that led to the rollover being postponed, a near real-time view of the actual rollover in resolvers and a significant increase in queries to the root of the DNS once the old key was revoked. Our analysis contributes significantly to identifying the causes of challenges observed during the rollover. We show that while from an end-user perspective, the roll indeed passed without major problems, there are many opportunities for improvement and important lessons to be learned from events that occurred over the entire duration of the rollover. Based on these lessons, we propose improvements to the process for future rollovers

    Failure to decrease HbA1c levels following TB treatment is associated with elevated Th1/Th17 CD4+ responses

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    Introduction: The rising global burden of metabolic disease impacts the control of endemic tuberculosis (TB) in many regions, as persons with diabetes mellitus (DM) are up to three times more likely to develop active TB than those without DM. Active TB can also promote glucose intolerance during both acute infection and over a longer term, potentially driven by aspects of the immune response. Identifying patients likely to have persistent hyperglycemia following TB treatment would enable closer monitoring and care, and an improved understanding of underlying immunometabolic dysregulation. // Methods: We measured the relationship of plasma cytokine levels, T cell phenotypes and functional responses with the change in hemoglobin A1c (HbA1c) before and after treatment of pulmonary TB in a prospective observational cohort in Durban, South Africa. Participants were stratified based on stable/increased HbA1c (n = 16) versus decreased HbA1c (n = 46) levels from treatment initiation to 12 month follow-up. // Results: CD62 P-selectin was up- (1.5-fold) and IL-10 downregulated (0.85-fold) in plasma among individuals whose HbA1c remained stable/increased during TB treatment. This was accompanied by increased pro-inflammatory TB-specific IL-17 production (Th17). In addition, Th1 responses were upregulated in this group, including TNF-α production and CX3CR1 expression, with decreased IL-4 and IL-13 production. Finally, the TNF-α+ IFNγ+ CD8+ T cells were associated with stable/increased HbA1c. These changes were all significantly different in the stable/increased HbA1c relative to the decreased HbA1c group. // Discussion: Overall, these data suggest that patients with stable/increased HbA1c had an increased pro-inflammatory state. Persistent inflammation and elevated T cell activity in individuals with unresolved dysglycemia following TB treatment may indicate failure to fully resolve infection or may promote persistent dysglycemia in these individuals, and further studies are needed to explore potential mechanisms
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