3,728 research outputs found

    Orbital and Spin Parameter Variations of Partial Eclipsing Low Mass X-ray Binary X 1822-371

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    We report our measurements for orbital and spin parameters of X 1822-371 using its X-ray partial eclipsing profile and pulsar timing from data collected by the Rossi X-ray Timing Explorer (RXTE). Four more X-ray eclipse times obtained by the RXTE 2011 observations were combined with historical records to trace evolution of orbital period. We found that a cubic ephemeris likely better describes evolution of the X-ray eclipse times during a time span of about 34 years with a marginal second order derivative of ddotPorb=(1.05pm0.59)imes1019ddot{P}_{orb}=(-1.05 pm 0.59) imes 10^{-19} s1^{-1}. Using the pulse arrival time delay technique, the orbital and spin parameters were obtained from RXTE observations from 1998 to 2011. The detected pulse periods show that the neutron star in X 1822-371 is continuously spun-up with a rate of dotPs=(2.6288pm0.0095)imes1012dot{P}_{s}=(-2.6288 pm 0.0095) imes 10^{-12} s s1^{-1}. Evolution of the epoch of the mean longitude l=pi/2l=pi /2 (i.e. Tpi/2T_{pi / 2}) gives an orbital period derivative value consistent with that obtained from the quadratic ephemeris evaluated by the X-ray eclipse but the detected Tpi/2T_{pi / 2} values are significantly and systematically earlier than the corresponding expected X-ray eclipse times by 90pm1190 pm 11 s. This deviation is probably caused by asymmetric X-ray emissions. We also attempted to constrain the mass and radius of the neutron star using the spin period change rate and concluded that the intrinsic luminosity of X 1822-371 is likely more than 103810^{38} ergs s1^{-1}.postprin

    Performance and simulated moment uncertainties of an ion spectrometer with asymmetric 2π field of view for ion measurements in space

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    Space plasma instruments provide 3D particle velocity distribution functions. Because of telemetry limitations, these cannot be transmitted in high time resolution and the plasma needs to be characterized by moments of the velocity distribution function. These moment uncertainties have vital effects on the reliability and accuracy of onboard plasma moments. We assess the measurement accuracy for magnetosheath and solar wind ions using an ion spectrometer with an asymmetric field of view designed for the all-sky measurement of low-energy ions in the magnetosheath and solar wind. We focus on moment uncertainties for the ideal spectrometer, not considering the background counts, which may have considerable effects on the uncertainties in real life. To obtain number density, bulk velocity, and temperature, different orders of moments are integrated assuming a Maxwellian velocity distribution. Based on the design specifications, we use simulations to estimate systematic and random errors for typical plasma conditions. We find that the spectrometer resolution is adequate for determining the density of solar wind (∼7% error) and magnetosheath ions (∼4% error). The resolution is also adequate for determining the temperature of solar wind (∼10% error) and magnetosheath ions (∼2% error). For high speed flows with a bulk velocity of 750 km/s and a temperature of 20 eV, the maximum density and temperature errors become 9% and 7%, respectively. The bulk velocity errors are less than 2% for all cases. The contributions of heavy ions to the systematic errors are less than 5% for magnetosheath ions and less than 8% for solar wind ions

    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

    Leg disorders in broiler chickens : prevalence, risk factors and prevention

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    Broiler (meat) chickens have been subjected to intense genetic selection. In the past 50 years, broiler growth rates have increased by over 300% (from 25 g per day to 100 g per day). There is growing societal concern that many broiler chickens have impaired locomotion or are even unable to walk. Here we present the results of a comprehensive survey of commercial flocks which quantifies the risk factors for poor locomotion in broiler chickens.We assessed the walking ability of 51,000 birds, representing 4.8 million birds within 176 flocks.We also obtained information on approximately 150 different management factors associated with each flock. At a mean age of 40 days, over 27.6% of birds in our study showed poor locomotion and 3.3% were almost unable to walk. The high prevalence of poor locomotion occurred despite culling policies designed to remove severely lame birds from flocks. We show that the primary risk factors associated with impaired locomotion and poor leg health are those specifically associated with rate of growth. Factors significantly associated with high gait score included the age of the bird (older birds), visit (second visit to same flock), bird genotype, not feeding whole wheat, a shorter dark period during the day, higher stocking density at the time of assessment, no use of antibiotic, and the use of intact feed pellets. The welfare implications are profound. Worldwide approximately 261010 broilers are reared within similar husbandry systems.We identify a range of management factors that could be altered to reduce leg health problems, but implementation of these changes would be likely to reduce growth rate and production. A debate on the sustainability of current practice in the production of this important food source is required

    Characterisation and expression of SPLUNC2, the human orthologue of rodent parotid secretory protein

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    We recently described the Palate Lung Nasal Clone (PLUNC) family of proteins as an extended group of proteins expressed in the upper airways, nose and mouth. Little is known about these proteins, but they are secreted into the airway and nasal lining fluids and saliva where, due to their structural similarity with lipopolysaccharide-binding protein and bactericidal/permeability-increasing protein, they may play a role in the innate immune defence. We now describe the generation and characterisation of novel affinity-purified antibodies to SPLUNC2, and use them to determine the expression of this, the major salivary gland PLUNC. Western blotting showed that the antibodies identified a number of distinct protein bands in saliva, whilst immunohistochemical analysis demonstrated protein expression in serous cells of the major salivary glands and in the ductal lumens as well as in cells of minor mucosal glands. Antibodies directed against distinct epitopes of the protein yielded different staining patterns in both minor and major salivary glands. Using RT-PCR of tissues from the oral cavity, coupled with EST analysis, we showed that the gene undergoes alternative splicing using two 5' non-coding exons, suggesting that the gene is regulated by alternative promoters. Comprehensive RACE analysis using salivary gland RNA as template failed to identify any additional exons. Analysis of saliva showed that SPLUNC2 is subject to N-glycosylation. Thus, our study shows that multiple SPLUNC2 isoforms are found in the oral cavity and suggest that these proteins may be differentially regulated in distinct tissues where they may function in the innate immune response

    Protective effect of stromal Dickkopf-3 in prostate cancer: opposing roles for TGFBI and ECM-1

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    Aberrant transforming growth factor–β (TGF-β) signaling is a hallmark of the stromal microenvironment in cancer. Dickkopf-3 (Dkk-3), shown to inhibit TGF-β signaling, is downregulated in prostate cancer and upregulated in the stroma in benign prostatic hyperplasia, but the function of stromal Dkk-3 is unclear. Here we show that DKK3 silencing in WPMY-1 prostate stromal cells increases TGF-β signaling activity and that stromal cellconditioned media inhibit prostate cancer cell invasion in a Dkk-3-dependent manner. DKK3 silencing increased the level of the cell-adhesion regulator TGF-β–induced protein (TGFBI) in stromal and epithelial cell-conditioned media, and recombinant TGFBI increased prostate cancer cell invasion. Reduced expression of Dkk-3 in patient tumors was associated with increased expression of TGFBI. DKK3 silencing reduced the level of extracellular matrix protein-1 (ECM-1) in prostate stromal cell-conditioned media but increased it in epithelial cell-conditioned media, and recombinant ECM-1 inhibited TGFBI-induced prostate cancer cell invasion. Increased ECM1 and DKK3 mRNA expression in prostate tumors was associated with increased relapse-free survival. These observations are consistent with a model in which the loss of Dkk-3 in prostate cancer leads to increased secretion of TGFBI and ECM-1, which have tumor-promoting and tumor-protective roles, respectively. Determining how the balance between the opposing roles of extracellular factors influences prostate carcinogenesis will be key to developing therapies that target the tumor microenvironment

    Tibial torus and toddler's fractures misdiagnosed as transient synovitis: a case series

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    <p>Abstract</p> <p>Introduction</p> <p>The high incidence of transient synovitis in early childhood makes it the first suspected pathology in a limping child. Trauma, which has long been regarded as a causative factor for transient synovitis, may be underestimated in a non-cooperative toddler.</p> <p>After excluding most serious conditions, such as septic arthritis, a speculative diagnosis of transient synovitis can be made, and this can easily mask a subtle musculoskeletal injury.</p> <p>Case presentations</p> <p>We report the cases of three Caucasian patients (two boys, aged 20-months- and three-years-old, and one girl, aged two-years-old), with tibial torus and toddler's fractures which were late-diagnosed due to an initial misdiagnosis of transient synovitis of the hip.</p> <p>Conclusion</p> <p>In a non-cooperative child musculoskeletal trauma can be mistaken as a simple causative factor for transient synovitis of the hip and this can easily prevent further investigation for a possible subtle musculoskeletal injury of the lower extremities.</p> <p>Our experience with the presented cases suggests the need to be more vigilant in the differential diagnosis of transient synovitis in young children.</p

    Longitudinal evaluation of aflatoxin exposure in two cohorts in south-western Uganda

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    Aflatoxins (AF) are a group of mycotoxins. AF exposure causes acute and chronic adverse health effects such as aflatoxicosis and hepatocellular carcinoma in human populations, especially in the developing world. In this study, AF exposure was evaluated using archived serum samples from human immunodeficiency virus (HIV)-seronegative participants from two cohort studies in south-western Uganda. AFB1-lysine (AFB-Lys) adduct levels were determined via HPLC fluorescence in a total of 713 serum samples from the General Population Cohort (GPC), covering eight time periods between 1989 and 2010. Overall, 90% (642/713) of the samples were positive for AFB-Lys and the median level was 1.58 pg mg(-1) albumin (range = 0.40-168 pg mg(-1) albumin). AFB-Lys adduct levels were also measured in a total of 374 serum samples from the Rakai Community Cohort Study (RCCS), across four time periods between 1999 and 2003. The averaged detection rate was 92.5% (346/374) and the median level was 1.18 pg mg(-1) albumin (range = 0.40-122.5 pg mg(-1) albumin). In the GPC study there were no statistically significant differences between demographic parameters, such as age, sex and level of education, and levels of serum AFB-Lys adduct. In the RCCS study, longitudinal analysis using generalised estimating equations revealed significant differences between the adduct levels and residential areas (p = 0.05) and occupations (p = 0.02). This study indicates that AF exposure in people in two populations in south-western Uganda is persistent and has not significantly changed over time. Data from one study, but not the other, indicated that agriculture workers and rural area residents had more AF exposure than those non-agricultural workers and non-rural area residents. These results suggest the need for further study of AF-induced human adverse health effects, especially the predominant diseases in the region

    Immunotherapy targeting isoDGR-protein damage extends lifespan in a mouse model of protein deamidation

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    \ua9 2023 The Authors. Published under the terms of the CC BY 4.0 license. Aging results from the accumulation of molecular damage that impairs normal biochemical processes. We previously reported that age-linked damage to amino acid sequence NGR (Asn-Gly-Arg) results in “gain-of-function” conformational switching to isoDGR (isoAsp-Gly-Arg). This integrin-binding motif activates leukocytes and promotes chronic inflammation, which are characteristic features of age-linked cardiovascular disorders. We now report that anti-isoDGR immunotherapy mitigates lifespan reduction of Pcmt1−/− mouse. We observed extensive accumulation of isoDGR and inflammatory cytokine expression in multiple tissues from Pcmt1−/− and naturally aged WT animals, which could also be induced via injection of isoDGR-modified plasma proteins or synthetic peptides into young WT animals. However, weekly injection of anti-isoDGR mAb (1 mg/kg) was sufficient to significantly reduce isoDGR-protein levels in body tissues, decreased pro-inflammatory cytokine concentrations in blood plasma, improved cognition/coordination metrics, and extended the average lifespan of Pcmt1−/− mice. Mechanistically, isoDGR-mAb mediated immune clearance of damaged isoDGR-proteins via antibody-dependent cellular phagocytosis (ADCP). These results indicate that immunotherapy targeting age-linked protein damage may represent an effective intervention strategy in a range of human degenerative disorders
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