229 research outputs found

    Contact Force Dependence on Relative Humidity: Investigations Using Atomic Force Microscopy

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    This paper deals with the ability of scanning force microscopy to determine contact forces of various materials. Indeed, with high spring constants at low relative humidity, the nature of the material can be determined by measurement of the contact force as the tip approaches. Cantilevers with a high spring constant are used to achieve solid-solid contact for the tip-sample system. The capillary force estimation provides information on the development of the height of the water meniscus formed between the tip and different surfaces depending on the relative humidity. Finally, we focus our attention on measurements of moduli of elasticity which vary with the physicochemical processes (precipitation, dissolution, water intercalation, dehydration) instigated by the variation in humidity. All experiments were conducted on various surfaces: more extensively on gypsum, but also on calcite, mica, graphite, brucite, aluminum, silver and glass

    A New Control Scheme for Three-Phase Non-Isolated Grid Feeding PV Inverter

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    The use of control algorithms in inverter topologies is becoming more attractive for integration of wind and photovoltaic (PV) energy with a grid. Among the various inverters, the non-isolated inverter topology has gotten a huge attention for fixing the problem of leakage current issue with other inverters. In this paper, a linear control strategy is offered for the grid connected non-isolated PV inverter. The proposed scheme consists of a proportional resonance (PR) controller with lag compensator (LC). This controller offers lower oscillation in output grid current and better steady state performance for the grid-tied PV inverter systems. The analytical comparison of proposed control scheme and the other control strategies are mentioned in this work. The simulation results indicate the improvements of the performance for the proposed controller in terms of reference tracking ability, total harmonic distortion (THD), and the supplied dc bus voltages of the grid-injected PV inverter systems. This proposed controller can enhance the performance of the PV systems by reducing energy consumption during load change and faulty condition

    Ring chromosome 20

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    Ring Chromosome 20 syndrome is a rare chromosomal disorder characterized by refractory epilepsy, with seizures in wakefulness and sleep, behavioral problems and mild to severe cognitive impairment. Facial dysmorphism or other congenital malformations are rarely reported making it difficult to diagnose the syndrome based on clinical findings alone. Therefore, diagnosis requires cytogenetic testing. More than 100 cases have been published since the initial report in 1972. In some patients, the ring (20) is found in all cells analyzed and in these cases, the ring is almost always accompanied by deletions of 20pter and/or 20qter. However, in the majority of cases the ring is present in only a proportion of cells, with two normal 20's in the remaining cells (mosaicism), and in these cases, no deletions of chromosome 20 have been observed. Patients with supernumerary r(20) chromosomes have also been identified, but these individuals do not generally have seizures and are not discussed in this review. Characterization by fluorescence in situ hybridization and array-based analysis has shed insight into the molecular composition and possible mechanisms of ring formation, in both the mosaic and non-mosaic patients. The age of onset of seizures correlates with the percentage of cells with the ring in mosaic patients. While the underlying etiology of the phenotype is still not understood, evidence is accumulating which suggests the deletion of candidate genes on chromosome 20 is not responsible. Cytogenetic analysis, rather than chromosomal microarray analysis is recommended for diagnosis of this syndrome, as the mosaic cases do not have copy number alterations and are therefore not identified by array-based analysis

    Prevalence and onset of comorbidities in the CDKL5 disorder differ from Rett syndrome

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    Background: Initially described as an early onset seizure variant of Rett syndrome, the CDKL5 disorder is now considered as an independent entity. However, little is currently known about the full spectrum of comorbidities that affect these patients and available literature is limited to small case series. This study aimed to use a large international sample to examine the prevalence in this disorder of comorbidities of epilepsy, gastrointestinal problems including feeding difficulties, sleep and respiratory problems and scoliosis and their relationships with age and genotype. Prevalence and onset were also compared with those occurring in Rett syndrome. Methods: Data for the CDKL5 disorder and Rett syndrome were sourced from the International CDKL5 Disorder Database (ICDD), InterRett and the Australian Rett syndrome Database (ARSD). Logistic regression (multivariate and univariate) was used to analyse the relationships between age group, mutation type and the prevalence of various comorbidities. Binary longitudinal data from the ARSD and the equivalent cross-sectional data from ICDD were examined using generalized linear models with generalized estimating equations. The Kaplan-Meier method was used to estimate the failure function for the two disorders and the log-rank test was used to compare the two functions. Results: The likelihood of experiencing epilepsy, GI problems, respiratory problems, and scoliosis in the CDKL5 disorder increased with age and males were more vulnerable to respiratory and sleep problems than females. We did not identify any statistically significant relationships between mutation group and prevalence of comorbidities. Epilepsy, GI problems and sleep abnormalities were more common in the CDKL5 disorder than in Rett syndrome whilst scoliosis and respiratory problems were less prevalent. Conclusion: This study captured a much clearer picture of the CDKL5 disorder than previously possible using the largest sample available to date. There were differences in the presentation of clinical features occurring in the CDKL5 disorder and in Rett syndrome, reinforcing the concept that CDKL5 is an independent disorder with its own distinctive characteristics

    Genome-wide interaction study of smoking and bladder cancer risk

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    Bladder cancer is a complex disease with known environmental and genetic risk factors. We performed a genome-wide interaction study (GWAS) of smoking and bladder cancer risk based on primary scan data from 3002 cases and 4411 controls from the National Cancer Institute Bladder Cancer GWAS. Alternative methods were used to evaluate both additive and multiplicative interactions between individual single nucleotide polymorphisms (SNPs) and smoking exposure. SNPs with interaction P values < 5 x 10(-) (5) were evaluated further in an independent dataset of 2422 bladder cancer cases and 5751 controls. We identified 10 SNPs that showed association in a consistent manner with the initial dataset and in the combined dataset, providing evidence of interaction with tobacco use. Further, two of these novel SNPs showed strong evidence of association with bladder cancer in tobacco use subgroups that approached genome-wide significance. Specifically, rs1711973 (FOXF2) on 6p25.3 was a susceptibility SNP for never smokers [combined odds ratio (OR) = 1.34, 95% confidence interval (CI) = 1.20-1.50, P value = 5.18 x 10(-) (7)]; and rs12216499 (RSPH3-TAGAP-EZR) on 6q25.3 was a susceptibility SNP for ever smokers (combined OR = 0.75, 95% CI = 0.67-0.84, P value = 6.35 x 10(-) (7)). In our analysis of smoking and bladder cancer, the tests for multiplicative interaction seemed to more commonly identify susceptibility loci with associations in never smokers, whereas the additive interaction analysis identified more loci with associations among smokers-including the known smoking and NAT2 acetylation interaction. Our findings provide additional evidence of gene-environment interactions for tobacco and bladder cancer

    Low birth weight in offspring of women with depressive and anxiety symptoms during pregnancy: results from a population based study in Bangladesh

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    <p>Abstract</p> <p>Background</p> <p>There is a high prevalence of antepartum depression and low birth weight (LBW) in Bangladesh. In high- and low-income countries, prior evidence linking maternal depressive and anxiety symptoms with infant LBW is conflicting. There is no research on the association between maternal mental disorders and LBW in Bangladesh. This study aims to investigate the independent effect of maternal antepartum depressive and anxiety symptoms on infant LBW among women in a rural district of Bangladesh.</p> <p>Methods</p> <p>A population-based sample of 720 pregnant women from two rural subdistricts was assessed for symptoms of antepartum depression, using the Edinburgh Postpartum Depression Scale (EPDS), and antepartum anxiety, using the State Trait Anxiety Inventory (STAI), and followed for 6-8 months postpartum. Infant birth weight of 583 (81%) singleton live babies born at term (≥37 weeks of pregnancy) was measured within 48 hours of delivery. Baseline data provided socioeconomic, anthropometric, reproductive, obstetric, and social support information. Trained female interviewers carried out structured interviews. Chi-square, Fisher's exact, and independent-sample <it>t </it>tests were done as descriptive statistics, and a multiple logistic regression model was used to identify predictors of LBW.</p> <p>Results</p> <p>After adjusting for potential confounders, depressive (OR = 2.24; 95% CI 1.37-3.68) and anxiety (OR = 2.08; 95% CI 1.30-3.25) symptoms were significantly associated with LBW (≤2.5 kg). Poverty, maternal malnutrition, and support during pregnancy were also associated with LBW.</p> <p>Conclusions</p> <p>This study provides evidence that maternal depressive and anxiety symptoms during pregnancy predict the LBW of newborns and replicates results found in other South Asian countries. Policies aimed at the detection and effective management of depressive and anxiety symptoms during pregnancy may reduce the burden on mothers and also act as an important measure in the prevention of LBW among offspring in Bangladesh.</p
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