238 research outputs found

    In situ characterization of laser-generated melt pools using synchronized ultrasound and high-speed X-ray imaging

    Get PDF
    Metal additive manufacturing is a fabrication method that forms a part by fusing layers of powder to one another. An energy source, such as a laser, is commonly used to heat the metal powder sufficiently to cause a molten pool to form, which is known as the melt pool. The melt pool can exist in the conduction or the keyhole mode where the material begins to rapidly evaporate. The interaction between the laser and the material is physically complex and difficult to predict or measure. In this article, high-speed X-ray imaging was combined with immersion ultrasound to obtain synchronized measurements of stationary laser-generated melt pools. Furthermore, two-dimensional and three-dimensional finite-element simulations were conducted to help explain the ultrasonic response in the experiments. In particular, the time-of-flight and amplitude in pulse-echo configuration were observed to have a linear relationship to the depth of the melt pool. These results are promising for the use of ultrasound to characterize the melt pool behavior and for finite-element simulations to aid in interpretation

    Are Hylobates lar Extirpated from China?

    Get PDF
    The Nangunhe Nature Reserve in Southwest Yunnan (PRC) has long been presumed to be the last stronghold of lar (or white-handed) gibbons (Hylobates lar) in China and the likely last place of occurrence of Hylobates lar yunnanensis. We conducted a comprehensive survey to assess the status of lar gibbons at Nangunhe. We found no visual or auditory evidence of them still residing at the reserve and therefore tentatively conclude that lar gibbons have become extinct in China. It appears that large-scale destruction of primary forests in the 1960s and 1970s brought about an initial decline in their numbers, and subsequent uncontrolled hunting has resulted in their extirpation. The situation for the six Chinese ape taxa is nothing less than disastrous, with 1 taxon assumed to have become extinct during the last few years, 1 taxon not having been confirmed since the 1980s, and 2 species at the very brink of extinction with only tens of individuals remaining in China

    Applying the selective Cu electroplating technique to light-emitting diodes

    Get PDF
    [[abstract]]We successfully fabricated a predefined patterned copper (Cu) substrate for thin GaN light-emitting diodes without barriers by the selective electroplating technique. The contours of Cu bumps fabricated using different electroplating modes and parameters were measured. We observed that the average thickness diminished with increasing current density. The current density conditions to obtain the best upright structure in the process were 40 and 80 mA/cm2.[[notice]]補正完畢[[incitationindex]]SCI[[booktype]]紙本[[booktype]]電子

    A multi-dimensional investigation of self-regulated learning in a blended classroom context : a case study on eLDa MOOC

    Get PDF
    Online systems such as massive open online courses (MOOCs) are new innovative learning technology in education. With the proliferation of MOOC systems, little has been mentioned about blended MOOC system and how it enhances students’ performance. Blended classroom is a form of learning taking place between two different activities of which one is online and the other is traditional teaching method using bricks and mortal classroom settings. This study reveals the effectiveness of blended classroom teaching for an undergraduate course. The module was embedded in an eLDa MOOC platform, which is a platform for delivery computing concepts, and Python programme course. This research aims to investigate students’ perceptions of self-regulated learning (SRL) habits. A multi-dimensional survey was designed to evaluate each aspect of SRL skills, motivation and attaining better grades within the course. This research analysis explores (a) cognitive process of students improving their self-regulated learning skills (b) potential of students’ preparedness and motivation to engage with the course content in a blended context (c) potential difference in addressing the relation among the methods of engagement and achievement in their weekly assessment results. The research applied an online self-regulated learning questionnaire (OSLQ) as the instrument for measuring the self-regulated learning skills of the students in the learning platform environment. In relation to developing a revised OSLQ to address the use of the instrument to measure self-regulated learning in an online blended classroom context. Data collection process was conducted on a sample of first year undergraduate students who took a seminar module via a blended course format. The results indicate the level of self-regulated learning explored from the measure of the self-regulation in the blended learning environment in this study

    Pituitary tumor transforming gene-1 haplotypes and risk of pituitary adenoma: a case-control study

    Get PDF
    <p>Abstract</p> <p>Background</p> <p>It has been suggested that pituitary adenoma results from accumulation of multiple genetic and/or epigenetic aberrations, which may be identified through association studies. As pituitary tumor transforming gene-1 (<it>PTTG1</it>)/securin plays a critical role in promoting genomic instability in pituitary neoplasia, the present study explored the association of <it>PTTG1 </it>haplotypes with the risk of pituitary adenoma.</p> <p>Methods</p> <p>We genotyped five <it>PTTG1 </it>haplotype-tagging SNPs (htSNP) by PCR-RFLP assays in a case-control study, which included 280 Han Chinese patients diagnosed with pituitary adenoma and 280 age-, gender- and geographically matched Han Chinese controls. Haplotypes were reconstructed according to the genotyping data and linkage disequilibrium status of the htSNPs.</p> <p>Results</p> <p>No significant differences in allele and genotype frequencies of the htSNPs were observed between pituitary adenoma patients and controls, indicating that none of the individual <it>PTTG1 </it>SNPs examined in this study is associated with the risk of pituitary adenoma. In addition, no significant association was detected between the reconstructed <it>PTTG1 </it>haplotypes and pituitary adenoma cases or the controls.</p> <p>Conclusions</p> <p>Though no significant association was found between <it>PTTG1 </it>haplotypes and the risk of pituitary adenoma, this is the first report on the association of individual <it>PTTG1 </it>SNPs or <it>PTTG1 </it>haplotypes with the risk of pituitary adenoma based on a solid study; it will provide an important reference for future studies on the association between genetic alterations in <it>PTTG1 </it>and the risk of pituitary adenoma or other tumors.</p

    Polymorphisms of the prion protein gene and their effects on litter size and risk evaluation for scrapie in Chinese Hu sheep

    Get PDF
    It is well known that scrapie is a fatal, neurodegenerative disease in sheep and goat, which belongs to the group of transmissible spongiform encephalopathies (TSEs) or prion diseases. It has been confirmed that the polymorphisms of prion protein gene (PRNP) at codons 136, 154, and 171 have strong relationship with scrapie in sheep. In the present study, nine polymorphisms of PRNP at codons 136, 154, and 171 and other six loci (at codons 101, 112, 127, 137, 138, and 152) were detected in 180 Chinese Hu sheep. All the alleles at codons 136, 154, and 171 have been identified and resulted in three new genotypes. The frequencies of predominant alleles were 85% (A136), 99.40% (R154), and 37.78% (Q171), respectively. The predominant haplotype ARQ has a relatively high frequency of 57.77%. The frequencies of dominant genotypes of ARR/ARQ and ARQ/ARQ were 30 and 26.67%, respectively. Three new found genotypes named ARQ/TRK, ARQ/TRR, and TRR/TRQ had the same lower frequencies (0.56%). The relationship of PRNP genotype with scrapie risk and litter size showed that the predominant genotypes are corresponded to the risk score of R1 (1.67%), R2 (32.22%), and R3 (42.22%). Just at the first parity, the individuals with ARH/ARH genotype had significantly larger litter size than the mean value and those with ARQ/ARQ and ARR/ARQ genotypes. In short, this study provided preliminary information about alleles and genotypes of PRNP in Chinese Hu sheep. It could be concluded that Hu sheep has a low susceptibility to natural scrapie, and the predominant PRNP genotype at least has no significant effect on litter size

    Comparison of children's self-reports of depressive symptoms among different family interaction types in northern Taiwan

    Get PDF
    <p>Abstract</p> <p>Background</p> <p>Previous research has shown that family interactions are associated with depressive symptoms in children. However, detailed classifications of family interaction types have not been studied thoroughly. This study aims to understand the types of family interactions children experience and to identify the specific types of family interactions that are associated with a higher risk of depressive symptoms in children.</p> <p>Methods</p> <p>Data used in the study was collected as part of the Child and Adolescent Behavior in Long term Evolution (CABLE) project in 2003. CABLE is a longitudinal cohort study that commenced in 2001 and collects data annually from children in Taipei city and Hsinchu county in northern Taiwan. The data analyzed in this study was that obtained from the sixth graders (aged 11 to 12 years old) in 2003. Of the 2,449 sixth graders, 51.2% were boys and 48.8% were girls. Factor analysis and cluster analysis were used to investigate the types of family interactions. One way ANOVA was used to establish the relationship between family interaction types and children's self-reports of depressive symptoms.</p> <p>Results</p> <p>Based on the results of factor analysis, the latent factors for family interactions included supporting activities, psychological control, parental discipline, behavioral supervision, and family conflict. After conducting cluster analysis using factor scores, four types of family interactions were revealed: supervised (29.66%), disciplined (13.56%), nurtured (40.96%) and conflict (15.82%). Children from the disciplined or conflict families were more likely to report depressive symptoms. Children from the nurtured families were least likely to report depressive symptoms.</p> <p>Conclusion</p> <p>Family interactions can be classified into four different types, which are related to children's self-reports of depressive symptoms. The creation of a family interaction environment that is beneficial for children's mental health is an important issue for health education and health promotion professionals.</p

    Association between the Cytotoxic T-Lymphocyte Antigen 4 +49G > A polymorphism and cancer risk: a meta-analysis

    Get PDF
    <p>Abstract</p> <p>Background</p> <p>As a key gene in the immunosurveillance of cell malignancy, Cytotoxic T-lymphocyte antigen 4 (CTLA-4 is an important negative regulator of T cell activation and proliferation. The CTLA-4 +49G > A polymorphism is one of the most commonly studied polymorphisms in this gene due to its association with cancer risks, but previous results have been conflicting.</p> <p>Methods</p> <p>We preformed a meta-analysis using 22 eligible case-control studies (including 32 datasets) with a total of 11,273 patients and 13,179 controls to summarize the existing data on the association between the <it>CTLA-4 </it>+49G > A polymorphism and cancer risk.</p> <p>Results</p> <p>Compared with the common <it>CTLA-4 </it>+49G > A GG genotype, the carriers of variant genotypes (<it>CTLA-4 </it>+49 GC/CC) had a 1.24-fold elevated risk of cancer (95% CI = 1.18-1.32, <it>P </it>< 0.05) under the dominant genetic model, as estimated using a fixed effect model. The effect of the <it>CTLA-4 </it>+49G > A polymorphism was further evaluated using stratification analysis. In four breast cancer studies, patients with the variant genotypes had a significantly increased risk of breast cancer (OR = 1.31, 95% CI = 1.17-1.48, <it>P </it>< 0.00001). A similar result was found in three skin cancer studies (OR = 1.30, 95% CI = 1.10-1.52, <it>P </it>= 0.001). In 26 solid tumor studies, subjects with the variant genotypes had a significantly higher risk of developing solid tumors (OR = 1.25, 95% CI = 1.18-1.33, <it>P </it>< 0.00001) compared with the 6 non-solid tumor studies (OR = 1.08, 95% CI = 0.79-1.48, <it>P </it>= 0.62). Patients with variant genotypes had significantly increased risk of non-epithelial tumors and epithelial tumors, with ORs of 1.23 (95% CI = 1.14-1.32, <it>P </it>< 0.00001) and 1.29 (95% CI = 1.17-1.41, <it>P </it>< 0.00001), respectively. It was also demonstrated that the increased risk of cancer associated with <it>CTLA-4 </it>+49G > A variant genotypes was more pronounced in Caucasians (OR = 1.29, 95% CI = 1.13-1.47, <it>P </it>= 0.0002), Asians (OR = 1.23, 95% CI = 1.16-1.32, <it>P </it>< 0.00001) and Chinese (OR = 1.23, 95% CI = 1.15-1.31, <it>P </it>< 0.00001).</p> <p>Conclusion</p> <p>Our meta-analysis suggests that the <it>CTLA-4 </it>+49G > A polymorphism genotypes (GA + AA) might be associated with an increased risk of cancer, especially in Caucasians and Chinese.</p

    Toll-Like Receptor 8 Agonist and Bacteria Trigger Potent Activation of Innate Immune Cells in Human Liver

    Get PDF
    This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.The study was supported by a Grant core funding from the Agency for Science Technology and Research (A*STAR, Singapore) and a Singapore Translational Research Investigator Award (NRMC/StaR/013/2012) to AB as well as NIHR Biomedical Centre, Oxford, WT 091663MA, NIAID1U19AI082630-01, Oxford Martin School funding and an NIHR Senior Investigator award to PK
    corecore