627 research outputs found

    Existence of Dynamical Scaling in the Temporal Signal of Time Projection Chamber

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    The temporal signals from a large gas detector may show dynamical scaling due to many correlated space points created by the charged particles while passing through the tracking medium. This has been demonstrated through simulation using realistic parameters of a Time Projection Chamber (TPC) being fabricated to be used in ALICE collider experiment at CERN. An interesting aspect of this dynamical behavior is the existence of an universal scaling which does not depend on the multiplicity of the collision. This aspect can be utilised further to study physics at the device level and also for the online monitoring of certain physical observables including electronics noise which are a few crucial parameters for the optimal TPC performance.Comment: 5 pages, 6 figure

    Drivers of organic molecular signatures in the Amazon River

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    Author Posting. © American Geophysical Union, 2021. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Global Biogeochemical Cycles 35(6), (2021): e2021GB006938, https://doi.org/10.1029/2021GB006938.As climate-driven El Niño Southern Oscillation (ENSO) events are projected to increase in frequency and severity, much attention has focused on impacts regarding ecosystem productivity and carbon balance in Amazonian rainforests, with comparatively little attention given to carbon dynamics in fluvial ecosystems. In this study, we compared the wet 2012 La Niña period to the following normal hydrologic period in the Amazon River. Elevated water flux during the La Niña period was accompanied by dilution of inorganic ion concentrations. Furthermore, the La Niña period exported 2.77 Tg C yr−1 more dissolved organic carbon (DOC) than the normal period, an increase greater than the annual amount of DOC exported by the Mississippi River. Using ultra-high-resolution mass spectrometry, we detected both intra- and interannual differences in dissolved organic matter (DOM) composition, revealing that DOM exported during the dry season and the normal period was more aliphatic, whereas compounds in the wet season and following the La Niña event were more aromatic, with ramifications for its environmental role. Furthermore, as this study has the highest temporal resolution DOM compositional data for the Amazon River to-date we showed that compounds were highly correlated to a 6-month lag in Pacific temperature and pressure anomalies, suggesting that ENSO events could impact DOM composition exported to the Atlantic Ocean. Therefore, as ENSO events increase in frequency and severity into the future it seems likely that there will be downstream consequences for the fate of Amazon Basin-derived DOM concurrent with lag periods as described here.This work was partially supported by National Science Foundation grant OCE-1464396 to Robert G. M. Spencer and funding from the Harbourton Foundation to Robert G. M. Spencer, R. Max Holmes, and Bernhard Peucker-Ehrenbrink.2021-12-1

    The pulse of the Amazon: fluxes of dissolved organic carbon, nutrients, and ions from the world's largest river

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    Author Posting. © American Geophysical Union, 2021. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Global Biogeochemical Cycles 35(4), (2021): e2020GB006895, https://doi.org/10.1029/2020GB006895.The Amazon River drains a diverse tropical landscape greater than 6 million km2, culminating in the world's largest export of freshwater and dissolved constituents to the ocean. Here, we present dissolved organic carbon (DOC), organic and inorganic nitrogen (DON, DIN), orthophosphate (PO43−), and major and trace ion concentrations and fluxes from the Amazon River using 26 samples collected over three annual hydrographs. Concentrations and fluxes were predominantly controlled by the annual wet season flood pulse. Average DOC, DON, DIN, and PO43− fluxes (±1 s.d.) were 25.5 (±1.0), 1.14 (±0.05), 0.82 (±0.03), and 0.063 (±0.003) Tg yr−1, respectively. Chromophoric dissolved organic matter absorption (at 350 nm) was strongly correlated with DOC concentrations, resulting in a flux of 74.8 × 106 m−2 yr−1. DOC and DON concentrations positively correlated with discharge while nitrate + nitrite concentrations negatively correlated, suggesting mobilization and dilution responses, respectively. Ammonium, PO43−, and silica concentrations displayed chemostatic responses to discharge. Major and trace ion concentrations displayed clockwise hysteresis (except for chloride, sodium, and rubidium) and exhibited either dilution or chemostatic responses. The sources of weathered cations also displayed seasonality, with the highest proportion of carbonate- and silicate-derived cations occurring during peak and baseflow, respectively. Finally, our seasonally resolved weathering model resulted in an average CO2 consumption yield of (3.55 ± 0.11) × 105 mol CO2 km−2 yr−1. These results represent an updated and temporally refined quantification of dissolved fluxes that highlight the strong seasonality of export from the world's largest river and set a robust baseline against which to gauge future change.This work was supported by a grant from the Harbourton Foundation to R. G. M. Spencer and R. M. Holmes. T. W. Drake was supported by ETH Zurich core funding to J. Six. R. G. M. Spencer was additionally supported by NSF OCE-1333157.2021-09-1

    Neoadjuvant Chemotherapy with or without Concurrent Hormone Therapy in Estrogen Receptor-Positive Breast Cancer:NACED-Randomized Multicenter Phase II Trial

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    Although in the neoadjuvant setting for estrogen receptor (ER)-positive breast cancers, chemotherapy or hormone therapy alone does not result in satisfactory tumor response, it is unknown whether concurrent chemo-endocrine therapy is superior to chemotherapy alone in clinical outcomes. We conducted a randomized phase II trial to test the responses of ER-positive patients to concurrent administration of chemo-endocrine therapy in the neoadjuvant setting. Women with stage II-III, ER-positive, invasive breast cancer (n=28) received paclitaxel followed by fluorouracil, epirubicin, cyclophosphamide (T-FEC) and were randomized to receive concurrent chemo-endocrine therapy consisting of goserelin administered subcutaneously for premenopausal women or an aromatase inhibitor for postmenopausal women. The primary endpoint was the pathological complete response (pCR) rate after neoadjuvant therapy. Twenty-eight patients were randomized. There were no significant differences in pCR rate between the concurrent group (12.5%;2/16) and the chemotherapy alone group (8.3%;1/12). Tumor size after therapy was significantly reduced in the concurrent therapy group (p=0.035), but not in the chemotherapy-alone group (p=0.622). Neoadjuvant chemotherapy with concurrent hormone therapy provided no significant improvement in pCR rate in ER-positive breast cancers. These preliminary results should be followed up by further studies

    The M3 muscarinic receptor Is required for optimal adaptive immunity to Helminth and bacterial infection

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    Innate immunity is regulated by cholinergic signalling through nicotinic acetylcholine receptors. We show here that signalling through the M3 muscarinic acetylcholine receptor (M3R) plays an important role in adaptive immunity to both Nippostrongylus brasiliensis and Salmonella enterica serovar Typhimurium, as M3R-/- mice were impaired in their ability to resolve infection with either pathogen. CD4 T cell activation and cytokine production were reduced in M3R-/- mice. Immunity to secondary infection with N. brasiliensis was severely impaired, with reduced cytokine responses in M3R-/- mice accompanied by lower numbers of mucus-producing goblet cells and alternatively activated macrophages in the lungs. Ex vivo lymphocyte stimulation of cells from intact BALB/c mice infected with N. brasiliensis and S. typhimurium with muscarinic agonists resulted in enhanced production of IL-13 and IFN-γ respectively, which was blocked by an M3R-selective antagonist. Our data therefore indicate that cholinergic signalling via the M3R is essential for optimal Th1 and Th2 adaptive immunity to infection

    Viral population estimation using pyrosequencing

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    The diversity of virus populations within single infected hosts presents a major difficulty for the natural immune response as well as for vaccine design and antiviral drug therapy. Recently developed pyrophosphate based sequencing technologies (pyrosequencing) can be used for quantifying this diversity by ultra-deep sequencing of virus samples. We present computational methods for the analysis of such sequence data and apply these techniques to pyrosequencing data obtained from HIV populations within patients harboring drug resistant virus strains. Our main result is the estimation of the population structure of the sample from the pyrosequencing reads. This inference is based on a statistical approach to error correction, followed by a combinatorial algorithm for constructing a minimal set of haplotypes that explain the data. Using this set of explaining haplotypes, we apply a statistical model to infer the frequencies of the haplotypes in the population via an EM algorithm. We demonstrate that pyrosequencing reads allow for effective population reconstruction by extensive simulations and by comparison to 165 sequences obtained directly from clonal sequencing of four independent, diverse HIV populations. Thus, pyrosequencing can be used for cost-effective estimation of the structure of virus populations, promising new insights into viral evolutionary dynamics and disease control strategies.Comment: 23 pages, 13 figure

    Isolation and Characterization of Maize PMP3 Genes Involved in Salt Stress Tolerance

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    Plasma membrane protein 3 (PMP3), a class of small hydrophobic polypeptides with high sequence similarity, is responsible for salt, drought, cold, and abscisic acid. These small hydrophobic ploypeptides play important roles in maintenance of ion homeostasis. In this study, eight ZmPMP3 genes were cloned from maize and responsive to salt, drought, cold and abscisic acid. The eight ZmPMP3s were membrane proteins and their sequences in trans-membrane regions were highly conserved. Phylogenetic analysis showed that they were categorized into three groups. All members of group II were responsive to ABA. Functional complementation showed that with the exception of ZmPMP3-6, all were capable of maintaining membrane potential, which in turn allows for regulation of intracellular ion homeostasis. This process was independent of the presence of Ca2+. Lastly, over-expression of ZmPMP3-1 enhanced growth of transgenic Arabidopsis under salt condition. Through expression analysis of deduced downstream genes in transgenic plants, expression levels of three ion transporter genes and four important antioxidant genes in ROS scavenging system were increased significantly in transgenic plants during salt stress. This tolerance was likely achieved through diminishing oxidative stress due to the possibility of ZmPMP3-1's involvement in regulation of ion homeostasis, and suggests that the modulation of these conserved small hydrophobic polypeptides could be an effective way to improve salt tolerance in plants

    Performance of Ultra-Deep Pyrosequencing in Analysis of HIV-1 pol Gene Variation

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    INTRODUCTION: Ultra-deep pyrosequencing (UDPS) has been used to detect minority variants within HIV-1 populations. Some aspects of the quality and reproducibility of UDPS have been previously evaluated, but comprehensive studies are still needed. PRINCIPAL FINDING: In this study the UDPS technology (FLX platform) was evaluated by analyzing a 120 base pair fragment of the HIV-1 pol gene from plasma samples from two patients and artificial mixtures of molecular clones. UDPS was performed using an optimized experimental protocol and an in-house data cleaning strategy. Nine samples and mixtures were analyzed and the average number of reads per sample was 19,404 (range 8,858-26,846). The two patient plasma samples were analyzed twice and quantification of viral variants was found to be highly repeatable for variants representing >0.27% of the virus population, whereas some variants representing 0.11-0.27% were detected in only one of the two UDPS runs. Bland-Altman analysis showed that a repeated measurement would have a 95% likelihood to lie approximately within ±0.5 log(10) of the initial estimate. A similar level of agreement was observed for variant frequency estimates in forward vs. reverse sequencing direction, but here the agreement was higher for common variants than for rare variants. UDPS following PCR amplification with alternative primers indicated that some variants may be incorrectly quantified due to primer-related selective amplification. Finally, the in vitro recombination rate during PCR was evaluated using artificial mixtures of clones and was found to be low. The most abundant in vitro recombinant represented 0.25% of all UDPS reads. CONCLUSION: This study demonstrates that this UDPS protocol results in low experimental noise and high repeatability, which is relevant for future research and clinical use of the UDPS technology. The low rate of in vitro recombination suggests that this UDPS system can be used to study genetic variants and mutational linkage

    Lessons learned in developing family medicine residency training programs in Japan

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    BACKGROUND: While family medicine is not well established as a discipline in Japan, a growing number of Japanese medical schools and training hospitals have recently started sougoushinryoubu (general medicine departments). Some of these departments are incorporating a family medicine approach to residency training. We sought to learn from family medicine pioneers of these programs lessons for developing residency training. METHODS: This qualitative project utilized a long interview research design. Questions focused on four topics: 1) circumstances when becoming chair/faculty member; 2) approach to starting the program; 3) how Western ideas of family medicine were incorporated; and 4) future directions. We analyzed the data using immersion/crystallization to identify recurring themes. From the transcribed data, we selected representative quotations to illustrate them. We verified the findings by emailing the participants and obtaining feedback. RESULTS: Participants included: five chairpersons, two program directors, and three faculty members. We identified five lessons: 1) few people understand the basic concepts of family medicine; 2) developing a core curriculum is difficult; 3) start with undergraduates; 4) emphasize clinical skills; and 5) train in the community. CONCLUSION: While organizational change is difficult, the identified lessons suggest issues that merit consideration when developing a family medicine training program. Lessons from complexity science could inform application of these insights in other countries and settings newly developing residency training
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