336 research outputs found

    Synthesis of intermetallic hydrogen storage materials based on TI-CR by glow discharge plasma

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    The TiCr2 intermetallic compound with the C36 hexagonal Laves phase has been synthesized by glow discharge plasma. The hydrogen absorption-desorption properties of the obtained alloy were investigated. It is shown that hydrogen storage capacity of material was 0.43 wt % at 85 °C and 8 atm

    First detection of 13CH in the interstellar medium

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    In recent years, a plethora of high spectral resolution observations of sub-mm and FIR transitions of methylidene (CH), have demonstrated this radical to be a valuable proxy for H2, that can be used for characterising molecular gas within the interstellar medium (ISM) on a Galactic scale, including the CO-dark component. Here we report the discovery of the 13CH isotopologue in the ISM using the upGREAT receiver on board SOFIA. We have detected the three hyperfine structure components of the 2THz frequency transition from its ground-state toward four high-mass star-forming regions and determine 13CH column densities. The ubiquity of molecules containing carbon in the ISM has turned the determination of the ratio between the abundances of carbon's two stable isotopes, 12C/13C, into a cornerstone for Galactic chemical evolution studies. Whilst displaying a rising gradient with Galactocentric distance, this ratio, when measured using observations of different molecules (CO, H2CO, and others) shows systematic variations depending on the tracer used. These observed inconsistencies may arise from optical depth effects, chemical fractionation or isotope-selective photo-dissociation. Formed from C+ either via UV-driven or turbulence-driven chemistry, CH reflects the fractionation of C+, and does not show any significant fractionation effects unlike other molecules previously used to determine the 12C/13C isotopic ratio which make it an ideal tracer for the 12C/13C ratio throughout the Galaxy. Therefore, by comparing the derived column densities of 13CH with previously obtained SOFIA data of the corresponding transitions of the main isotopologue 12CH, we derive 12C/13C isotopic ratios toward Sgr B2(M), G34.26+0.15, W49(N) and W51E. Adding our values derived from 12/13CH to previous calculations of the Galactic isotopic gradient we derive a revised value of 12C/13C = 5.85(0.50)R_GC + 15.03(3.40)

    Insulin resistance and glycemic abnormalities are associated with deterioration of left ventricular diastolic function: a cross-sectional study

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    <p>Abstract</p> <p>Background</p> <p>Left ventricular diastolic dysfunction (LVDD) is considered a precursor of diabetic cardiomyopathy, while insulin resistance (IR) is a precursor of type 2 diabetes mellitus (T2DM) and independently predicts heart failure (HF). We assessed whether IR and abnormalities of the glucose metabolism are related to LVDD.</p> <p>Methods</p> <p>We included 208 patients with normal ejection fraction, 57 (27%) of whom had T2DM before inclusion. In subjects without T2DM, an oral glucose tolerance test (oGTT) was performed. IR was assessed using the Homeostasis Model Assessment of Insulin Resistance (HOMA-IR). The lower limit of the top quartile of the HOMA-IR distribution (3.217) was chosen as threshold for IR. LVDD was verified according to current guidelines.</p> <p>Results</p> <p>IR was diagnosed in 38 (18%) patients without a history of diabetes. The prevalence of LVDD was 92% in subjects with IR vs. 72% in patients without IR (n = 113), respectively (p = 0.013). In the IR group, the early diastolic mitral inflow velocity (E) in relation to the early diastolic tissue Doppler velocity (averaged from the septal and lateral mitral annulus, E'av) ratio (E/E'av) was significantly higher compared to those without IR (9.8 [8.3-11.5] vs. 8.1 [6.6-11.0], p = 0.011). This finding remains significant when patients with IR and concomitant T2DM based on oGTT results were excluded (E/E'av ratio 9.8 [8.2-11.1)] in IR vs. 7.9 [6.5-10.5] in those without both IR and T2DM, p = 0.014). There were significant differences among patients with and without LVDD regarding the HOMA-IR (1.71 [1.04-3.88] vs. 1.09 [0.43-2.2], p = 0.003). The HOMA-IR was independently associated with LVDD on multivariate logistic regression analysis, a 1-unit increase in HOMA-IR value was associated with an odds ratio for prevalent LVDD of 2.1 (95% CI 1.3-3.1, p = 0.001). Furthermore, the E/E'av ratio increases along the glucose metabolism status from normal glucose metabolism (7.6 [6.2-10.1]) to impaired glucose tolerance (8.8 [7.4-11.0]) and T2DM (10.5 [8.1-13.2]), respectively (p < 0.001).</p> <p>Conclusions</p> <p>Insulin resistance is independently associated with LVDD in subjects without overt T2DM. Patients with IR and glucose metabolism disorders might represent a target population to prevent the development of HF. Screening programs for glucose metabolism disturbances should address the assessment of diastolic function and probably IR.</p

    Infant RSV immunoprophylaxis changes nasal epithelial DNA methylation at 6 years of age

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    BackgroundRespiratory syncytial virus (RSV) infection has been associated with childhood wheeze and asthma, and potential mechanisms include persistent epigenetic effects.MethodsIn the randomized, placebo-controlled MAKI trial, 429 preterm infants randomly received RSV immunoprophylaxis with palivizumab or placebo during their first RSV season. Children were followed until age 6 for asthma evaluation. DNA methylation in cells obtained by nasal brushes at age 6 was measured by Illumina MethylationEPIC array.ResultsRSV immunoprophylaxis in infancy had a significant impact on global methylation patterns in nasal cells at age 6. The first principal component (PC) related to the immunoprophylaxis intervention was enriched for the pathway "detection of chemical stimulus involved in sensory perception of smell" and "T cell differentiation." Subsequent analysis of these PCs indicated an effect of RSV immunoprophylaxis on cell type composition of nasal brushed cells. Three CpG sites, cg18040241, cg08243963, and cg19555973 which are annotated to genes GLB1L2, SC5D, and BPIFB1, were differentially methylated at genome-wide significance, but were not associated with asthma. ConclusionThe study provides the first proof of concept that RSV immunoprophylaxis during infancy has long-term effects on nasal epigenetic signatures at age 6, relating to host sensory perception, epidermal growth factor receptor signaling, and adaptive immune responses.</p

    Design and Performance of a Sideband Separating SIS Mixer for 800-950 GHz

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    We present the design and results of characterization of a new sideband separating (2SB) mixer for 800-950GHz, based on superconductor-insulator-superconductor (SIS) junctions. This is the first waveguide 2SB SIS mixer demonstrated at such a high frequency. The design is following the classical quadrature hybrid architecture, meanwhile additional attention was put on the reduction of reflections in the RF structure in order to minimize the RF imbalance, to achieve a high image rejection ratio (IRR). The RF waveguide block was manufactured by micromilling and populated by single-ended SIS mixers developed earlier for upgrade of the CHAMP+ high-band array on the APEX telescope. These SIS mixers have double-sideband (DSB) noise temperatures from 210 to 400K. The assembled 2SB mixer yields a SSB noise temperature from 450 to 900K, with an IRR above 15dB in 95 of the band. Comparing the DSB and the SSB sensitivities, we find that the waveguide losses are as low as expected and do not exceed 0.6dB. The presented mixer is a prototype for use in a 2SB dual polarization receiver planned for deployment on the APEX telescope

    Combined magnetic resonance coronary artery imaging, myocardial perfusion and late gadolinium enhancement in patients with suspected coronary artery disease

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    <p>Abstract</p> <p>Background</p> <p>Cardiovascular Magnetic Resonance (CMR) imaging offers methods for the detection of ischemia and myocardial infarction as well as visualization of the coronary arteries (MRCA). However, a direct comparison of adenosine perfusion (PERF), late gadolinium enhancement (LGE) and MRCA or the results of their combination has not been performed. Aim of the study was to evaluate the feasibility/diagnostic performance of rest/stress perfusion, late gadolinium enhancement and MRCA and their combination in patients with suspected coronary artery disease (CAD) in comparison to invasive angiography.</p> <p>Methods</p> <p>Fifty-four patients (60 ± 10 years, 35 men, CAD 48%) underwent CMR including MRCA (steady state free precession, navigator whole heart approach, spatial resolution 0.7 × 0.7 × .0.9 mm, trigger delay and temporal resolution adjusted individually), stress PERF (adenosine 140 μg/min/kg), rest PERF (SSFP, 3 short axis, 1 saturation prepulse per slice) and LGE (3D inversion recovery technique) using Gd-BOPTA. Images were analyzed visually. Stenosis >50% in invasive angiography was considered significant.</p> <p>Results</p> <p>Mean study time was 68 ± 11 minutes. Sensitivity for PERF, LGE, MRCA and the combination of PERF/LGE and PERF/LGE/MRCA was 87%, 50%, 91%, 88% and 92%, respectively and specificity 88%, 96%, 46%, 88% and 56%, respectively. If image quality of MRCA was excellent (n = 18) the combination of MRCA/PERF/LGE yield a sensitivity of 86% and specificity of 91%. However, no test or combination improved diagnostic performance significantly compared to PERF alone.</p> <p>Conclusion</p> <p>In patients with CAD, the combination of stress PERF, LGE and MRCA is feasible. When compared to invasive angiography, adenosine stress perfusion outperforms CMR coronary angiography in direct comparison and yields the best results with non-significant improvement in combination with LGE and significant deterioration in combination with MRCA. MRCA may be of additional value only in a minority of patients with excellent image quality.</p

    Genotypic tropism testing by massively parallel sequencing: qualitative and quantitative analysis

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    <p>Abstract</p> <p>Background</p> <p>Inferring viral tropism from genotype is a fast and inexpensive alternative to phenotypic testing. While being highly predictive when performed on clonal samples, sensitivity of predicting CXCR4-using (X4) variants drops substantially in clinical isolates. This is mainly attributed to minor variants not detected by standard bulk-sequencing. Massively parallel sequencing (MPS) detects single clones thereby being much more sensitive. Using this technology we wanted to improve genotypic prediction of coreceptor usage.</p> <p>Methods</p> <p>Plasma samples from 55 antiretroviral-treated patients tested for coreceptor usage with the Monogram Trofile Assay were sequenced with standard population-based approaches. Fourteen of these samples were selected for further analysis with MPS. Tropism was predicted from each sequence with geno2pheno<sub>[coreceptor]</sub>.</p> <p>Results</p> <p>Prediction based on bulk-sequencing yielded 59.1% sensitivity and 90.9% specificity compared to the trofile assay. With MPS, 7600 reads were generated on average per isolate. Minorities of sequences with high confidence in CXCR4-usage were found in all samples, irrespective of phenotype. When using the default false-positive-rate of geno2pheno<sub>[coreceptor] </sub>(10%), and defining a minority cutoff of 5%, the results were concordant in all but one isolate.</p> <p>Conclusions</p> <p>The combination of MPS and coreceptor usage prediction results in a fast and accurate alternative to phenotypic assays. The detection of X4-viruses in all isolates suggests that coreceptor usage as well as fitness of minorities is important for therapy outcome. The high sensitivity of this technology in combination with a quantitative description of the viral population may allow implementing meaningful cutoffs for predicting response to CCR5-antagonists in the presence of X4-minorities.</p

    Registered Replication Report on Fischer, Castel, Dodd, and Pratt (2003)

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    The attentional spatial-numerical association of response codes (Att-SNARC) effect (Fischer, Castel, Dodd, & Pratt, 2003)—the finding that participants are quicker to detect left-side targets when the targets are preceded by small numbers and quicker to detect right-side targets when they are preceded by large numbers—has been used as evidence for embodied number representations and to support strong claims about the link between number and space (e.g., a mental number line). We attempted to replicate Experiment 2 of Fischer et al. by collecting data from 1,105 participants at 17 labs. Across all 1,105 participants and four interstimulus-interval conditions, the proportion of times the effect we observed was positive (i.e., directionally consistent with the original effect) was .50. Further, the effects we observed both within and across labs were minuscule and incompatible with those observed by Fischer et al. Given this, we conclude that we failed to replicate the effect reported by Fischer et al. In addition, our analysis of several participant-level moderators (finger-counting habits, reading and writing direction, handedness, and mathematics fluency and mathematics anxiety) revealed no substantial moderating effects. Our results indicate that the Att-SNARC effect cannot be used as evidence to support strong claims about the link between number and space

    Systemic Complement Activation in Age-Related Macular Degeneration

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    Dysregulation of the alternative pathway (AP) of complement cascade has been implicated in the pathogenesis of age-related macular degeneration (AMD), the leading cause of blindness in the elderly. To further test the hypothesis that defective control of complement activation underlies AMD, parameters of complement activation in blood plasma were determined together with disease-associated genetic markers in AMD patients. Plasma concentrations of activation products C3d, Ba, C3a, C5a, SC5b-9, substrate proteins C3, C4, factor B and regulators factor H and factor D were quantified in patients (n = 112) and controls (n = 67). Subjects were analyzed for single nucleotide polymorphisms in factor H (CFH), factor B-C2 (BF-C2) and complement C3 (C3) genes which were previously found to be associated with AMD. All activation products, especially markers of chronic complement activation Ba and C3d (p<0.001), were significantly elevated in AMD patients compared to controls. Similar alterations were observed in factor D, but not in C3, C4 or factor H. Logistic regression analysis revealed better discriminative accuracy of a model that is based only on complement activation markers Ba, C3d and factor D compared to a model based on genetic markers of the complement system within our study population. In both the controls' and AMD patients' group, the protein markers of complement activation were correlated with CFH haplotypes
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