139 research outputs found

    Seismic Capacity of Reinforced Concrete Interior Flat Plate Connections

    Get PDF
    The demand for modular steel buildings (MSBs) has increased because of the improved quality, fast on-site installation, and lower cost of construction. Steel braced frames are usually utilized to form the lateral load resisting system of MSBs. During earthquakes, the seismic energy is dissipated through yielding of the components of the braced frames, which results in residual drifts. Excessive residual drifts complicate the repair of damaged structures or render them irreparable. Researchers have investigated the use of superelastic shape memory alloys (SMAs) in steel structures to reduce the seismic residual deformations. This study explores the potential of using SMA braces to improve the seismic performance of typical modular steel braced frames. The study utilizes incremental dynamic analysis to judge on the benefits of using such a system. It is observed that utilizing superelastic SMA braces at strategic locations can significantly reduce the inter-storey residual drifts

    Lesson study as teacher development strategy: a case study of primary schools in Riyadh, Saudi Arabia

    Get PDF
    This mixed-methods case study investigated the perspectives of teachers (T) and school leaders (SL) regarding the impact of Lesson Study (LS) as a school-based strategy for teacher professional development in KSA. Specifically, the study explored how the model helps in enhancing the content knowledge (CK), pedagogical content knowledge (PCK) and building a collaborative learning community based on the views of teachers and school leaders. Overall, a total of 54 participants including 50 teachers (25 males and 25 females) and 4 school leaders took part in this research study. More specifically, 50 teachers answered the questionnaires and 12 out of them were interviewed in addition to 4 school leaders (2 males and 2 females). The five key research questions which guided the study focused on examining primary school teachers and school leaders’ perceptions of the impact of LS on developing content knowledge and pedagogical content knowledge of Maths, Science and Arabic. In addition, the perceived influence of LS on school-based collaborative learning communities, the perceived benefits of implementing LS and perceived challenges to implementation in primary school context were closely investigated. Literature pertaining to teacher professional development (PD) and LS was reviewed. Data from questionnaires for teachers and interviews with both teachers and school leaders were examined both quantitatively and qualitatively to define common categories, themes, and connections to each of the research questions. The findings indicated that teachers and their school leaders believed that the participation of teachers in LS model can enhance teachers' CK, PCK, and can build a collaborative learning community which leads to breaking the culture of isolation in the school. This study examined the benefits and challenges while participating in LS. The findings suggested that the most frequently cited benefits were obtained by improving teacher performance as a result of participating in LS, improving student outcomes, ability to link daily teaching practices to long term objectives, and changes in motivation and a sense of effectiveness. The major challenges were the scheduling of meeting times, insufficient training of teachers ahead of implementing LS, insufficient understanding of LS by some teachers, the lack of sufficient support and resources that enable high-quality implementation of LS, teachers lacking CK when implementing LS, the lack of long-term vision for the implementation of LS, teachers’ lack of PCK when implementing LS as well as the existence of negative attitudes about LS among some teachers. In summary, the findings in this study suggested that LS was an effective model of professional development for teachers as LS helped them become better and more informed teachers. Recommendations were suggested to address the identified challenges

    Management of solitary fibrous tumours of the pleura:a systematic review and meta-analysis

    Get PDF
    Background:Solitary fibrous tumours of the pleura (SFTP), or pleural fibromas, are rare tumours that generally, but not universally, follow a benign course. Surgical resection is the standard treatment, but there are no evidence-based guidelines regarding the management of these tumours. Methods:Five databases were searched from inception to April 1, 2019 for studies reporting on SFTP management. Results:Twenty-seven studies met the inclusion criteria (1542 patients, all non-comparative case series); 98% of these patients underwent resection and all SFTP included were pathologically diagnosed. 394 out of 1299 cases (30.5%, 95% CI 27.8-32.8%) were malignant with recurrence rates of between 0% and 42.9%. A pleural effusion was always associated with a negative outcome, but no other features were consistently reported to have negative associations. Preoperative biopsies incorrectly reported malignant histology in two studies. Over 25% of cases of recurrence occurred when a complete (R0) resection had been achieved. The first recurrence occurred >5 years after the initial resection in at least 23% of cases. Conclusions:There is strong evidence to support long-term surveillance after surgical resection of SFTP, even where a complete (R0) resection has been achieved; however, there is no clear evidence to inform clinicians regarding the selection of patients who should undergo resection. The rates of malignant SFTP and SFTP recurrence are higher than previously reported. Only those that were pathologically diagnosed or resected were included, which may bias the data towards more aggressive tumours. Data collection on radiologically diagnosed SFTP is required to draw conclusions regarding the timing and need for intervention

    Determinants of Success in National Programs to Eliminate Lymphatic Filariasis: a Perspective Identifying Essential Elements and Research Needs

    Get PDF
    The Global Programme to Eliminate Lymphatic Filariasis (GPELF) was launched in 2000. To understand why some national programs have been more successful than others, a panel of individuals with expertise in LF elimination efforts met to assess available data from programs in 8 countries. The goal was to identify: 1) the factors determining success for national LF elimination programs (defined as the rapid, sustained reduction in microfilaremia/ antigenemia after repeated mass drug administration [MDA]); 2) the priorities for operational research to enhance LF elimination efforts. Of more than 40 factors identified, the most prominent were 1) initial level of LF endemicity; 2) effectiveness of vector mosquitoes; 3) MDA drug regimen; 4) population compliance. Research important for facilitating program success was identified as either biologic (i.e., [1] quantifying differences in vectorial capacity; [2] identifying seasonal variations affecting LF transmission) or programmatic (i.e., [1] identifying quantitative thresholds, especially the population compliance levels necessary for success, and the antigenemia or microfilaremia prevalence at which MDA programs can stop with minimal risk of resumption of transmission; [2] defining optimal drug distribution strategies and timing; [3] identifying those individuals who are “persistently non- compliant” during MDAs, the reasons for this non-compliance and approaches to overcoming it). While addressing these challenges is important, many key determinants of program success are already clearly understood; operationalizing these as soon as possible will greatly increase the potential for national program success

    Critical analysis of the utility of initial pleural aspiration in the diagnosis and management of suspected malignant pleural effusion

    Get PDF
    INTRODUCTION:Current guidelines recommend an initial pleural aspiration in the investigation and management of suspected malignant pleural effusions (MPEs) with the aim of establishing a diagnosis, identifying non-expansile lung (NEL) and, at times, providing a therapeutic procedure. A wealth of research has been published since the guidelines suggesting that results and outcomes from an aspiration may not always provide sufficient information to guide management. It is important to establish the validity of these findings in a 'real world' population. METHODS:A retrospective analysis was conducted of all patients who underwent pleural fluid (PF) sampling, in a single centre, over 3 years to determine the utility of the initial aspiration. RESULTS:A diagnosis of MPE was confirmed in 230/998 (23%) cases, a further 95/998 (9.5%) were presumed to represent MPE. Transudative biochemistry was found in 3% of cases of confirmed MPE. Positive PF cytology was only sufficient to guide management in 45/140 (32%) cases. Evidence of pleural thickening on CT was associated with both negative cytology (χ2 1df=26.27, p<0.001) and insufficient samples (χ2 1df=10.39, p=0.001). In NEL 44.4% of patients did not require further procedures after pleurodesis compared with 72.7% of those with expansile lung (χ2 1df=5.49, p=0.019). In patients who required a combined diagnostic and therapeutic aspiration 106/113 (93.8%) required further pleural procedures. CONCLUSIONS:An initial pleural aspiration does not achieve either definitive diagnosis or therapy in the majority of patients. A new pathway prioritising symptom management while reducing procedures should be considered

    Differential Gene Expression in Cord Blood of Infants Diagnosed with Cerebral Palsy: A Pilot Analysis of the Beneficial Effects of Antenatal Magnesium Cohort

    Get PDF
    The Beneficial Effects of Antenatal Magnesium clinical trial was conducted between 1997 and 2007, and demonstrated a significant reduction in cerebral palsy (CP) in preterm infants who were exposed to peripartum magnesium sulfate (MgSO4). However, the mechanism by which MgSO4 confers neuroprotection remains incompletely understood. Cord blood samples from this study were interrogated during an era when next-generation sequencing was not widely accessible and few gene expression differences or biomarkers were identified between treatment groups. Our goal was to use bulk RNA deep sequencing to identify differentially expressed genes comparing the following four groups: newborns who ultimately developed CP treated with MgSO4 or placebo, and controls (newborns who ultimately did not develop CP) treated with MgSO4 or placebo. Those who died after birth were excluded. We found that MgSO4 upregulated expression of SCN5A only in the control group, with no change in gene expression in cord blood of newborns who ultimately developed CP. Regardless of MgSO4 exposure, expression of NPBWR1 and FTO was upregulated in cord blood of newborns who ultimately developed CP compared with controls. These data support that MgSO4 may not exert its neuroprotective effect through changes in gene expression. Moreover, NPBWR1 and FTO may be useful as biomarkers and may suggest new mechanistic pathways to pursue in understanding the pathogenesis of CP. The small number of cases ultimately available for this secondary analysis, with male predominance and mild CP phenotype, is a limitation of the study. In addition, differentially expressed genes were not validated by qRT-PCR

    Recruiting a New Substrate for Triacylglycerol Synthesis in Plants: The Monoacylglycerol Acyltransferase Pathway

    Get PDF
    BACKGROUND: Monoacylglycerol acyltransferases (MGATs) are predominantly associated with lipid absorption and resynthesis in the animal intestine where they catalyse the first step in the monoacylglycerol (MAG) pathway by acylating MAG to form diacylglycerol (DAG). Typical plant triacylglycerol (TAG) biosynthesis routes such as the Kennedy pathway do not include an MGAT step. Rather, DAG and TAG are synthesised de novo from glycerol-3-phosphate (G-3-P) by a series of three subsequent acylation reactions although a complex interplay with membrane lipids exists. METHODOLOGY/PRINCIPAL FINDINGS: We demonstrate that heterologous expression of a mouse MGAT acyltransferase in Nicotiana benthamiana significantly increases TAG accumulation in vegetative tissues despite the low levels of endogenous MAG substrate available. In addition, DAG produced by this acyltransferase can serve as a substrate for both native and coexpressed diacylglycerol acyltransferases (DGAT). Finally, we show that the Arabidopsis thaliana GPAT4 acyltransferase can produce MAG in Saccharomyces cerevisiae using oleoyl-CoA as the acyl-donor. CONCLUSIONS/SIGNIFICANCE: This study demonstrates the concept of a new method of increasing oil content in vegetative tissues by using MAG as a substrate for TAG biosynthesis. Based on in vitro yeast assays and expression results in N. benthamiana, we propose that co-expression of a MAG synthesising enzyme such as A. thaliana GPAT4 and a MGAT or bifunctional M/DGAT can result in DAG and TAG synthesis from G-3-P via a route that is independent and complementary to the endogenous Kennedy pathway and other TAG synthesis routes

    Betaine and nano-emulsified vegetable oil supplementation for improving carcass and meat quality characteristics of broiler chickens under heat stress conditions

    Get PDF
    IntroductionThis research aimed to examine the effects of water-added betaine (BET) and/or nano-emulsified vegetable oil (MAGO) on carcass and meat quality characteristics of broilers raised under thermoneutral (TN) and heat stress (HS) conditions.MethodsOn day 21, 640 birds (Ross 308) were randomly assigned to one of two thermal conditions (thermoneutral 22 ± 1°C and heat stress 32 ± 1°C) each containing four treatment groups: Control, BET, MAGO, and a mixture of both (BETMAGO) in a 2 × 4 factorial arrangement (eight groups). Each group has eight replicates, with ten birds each. The birds' carcass and meat quality characteristics were evaluated at 35 days.Results and discussionThe dressing percentage, breast, leg, wing, heart, initial pH, color change, cooking loss (CL), water-holding capacity (WHC), shear force (SF), and texture profile with exception of springiness significantly affected by the treatments. The results showed that HS had negative effects on carcass weight and relative weights of the breast, spleen, and heart. Moreover, HS increased dressing percentage, wing, initial pH, final core temperature, initial lightness, WHC, and hardness. Significant differences in interactions between treatments and temperature were observed in the spleen, WHC, and SF.ConclusionWater supplemented with BET effectively improved carcass dressing percentage, breast weight, and meat quality in terms of water-holding capacity and tenderness under HS conditions. More studies on the use of BET and/or MAGO at different levels were recommended

    Epithelioid Angiosarcoma of the Small Intestine After Occupational Exposure to Radiation and Polyvinyl Chloride: A case Report and Review of Literature

    Get PDF
    Angiosarcomas represent 1–2% of soft tissue sarcomas and most frequently occur in the subcutis. They may affect internal organs, such as the heart, liver, and spleen, and only rarely do they emerge in the gastrointestinal tract. The association between angiosarcomas and certain toxic chemical substances or previous external-beam radiation therapy is well documented

    The association between retinal vascular geometry changes and diabetic retinopathy and their role in prediction of progression: an exploratory study

    Get PDF
    Background: The study describes the relationship of retinal vascular geometry (RVG) to severity of diabetic retinopathy (DR), and its predictive role for subsequent development of proliferative diabetic retinopathy (PDR). Methods. The research project comprises of two stages. Firstly, a comparative study of diabetic patients with different grades of DR. (No DR: Minimal non-proliferative DR: Severe non-proliferative DR: PDR) (10:10: 12: 19). Analysed RVG features including vascular widths and branching angles were compared between patient cohorts. A preliminary statistical model for determination of the retinopathy grade of patients, using these features, is presented. Secondly, in a longitudinal predictive study, RVG features were analysed for diabetic patients with progressive DR over 7 years. RVG at baseline was examined to determine risk for subsequent PDR development. Results: In the comparative study, increased DR severity was associated with gradual vascular dilatation (p = 0.000), and widening of the bifurcating angle (p = 0.000) with increase in smaller-child-vessel branching angle (p = 0.027). Type 2 diabetes and increased diabetes duration were associated with increased vascular width (p = <0.05 In the predictive study, at baseline, reduced small-child vascular width (OR = 0.73 (95 CI 0.58-0.92)), was predictive of future progression to PDR. Conclusions: The study findings suggest that RVG alterations can act as novel markers indicative of progression of DR severity and establishment of PDR. RVG may also have a potential predictive role in determining the risk of future retinopathy progression. © 2014 Habib et al.; licensee BioMed Central Ltd
    corecore