20 research outputs found
ACCELERATION PROGRAM and EXCELLENCE CLASS POLICY
Get PDFThe policy of acceleration programs and superior classes is a step taken by the government to support bright and talented children. A number of studies have been conducted to examine the implementation of this acceleration program. However, along with the emergence of new policies regarding gifted children, it is important to conduct more in- depth research on this subject. This study aims to describe the advantages, disadvantages, and ideal vision of excellent schools and acceleration programs. The method used in this research is descriptive qualitative with a literature study approach. The results of the social theory review will present various concepts and definitions related to excellent schools and acceleration programs
Influences of Shot Peening Parameters on Mechanical Properties and Fatigue Behavior of 316 L Steel: Experimental, Taguchi Method and Response Surface Methodology
No full textSevere plastic deformation methods like shot peening (SP) are known as efficient surface treatments and grain refining processes which afford more effective properties in metallic materials. In the current research, a comprehensive study was carried out on SP of AISI 316 L steel. It included 42 different SP treatments with a wide range of Almen intensities of 12–27 A and various coverage degrees (100%–1500%). Several experimental tests were conducted in order to explore the microstructure, grain size, surface topography, hardness, wettability, and residual stresses of the specimens. Next, two different approaches including Taguchi method (TM), and response surface methodology (RSM) were deployed for modeling, analysis, and optimization. RSM and TM were used to examine the influence of the effective parameters. Based on the optimized results, the fatigue behavior of the selected treatments was investigated experimentally in both smooth and notched specimens. Graphical abstract: [Figure not available: see fulltext.]. © 2021, The Author(s)
Fabbisogni energetici per edifici caratterizzanti il terziario in Italia: aspetti termici ed illuminotecnici
Get PDFIl presente lavoro verte sull'individuazione di benchmark di fabbisogno energetico per edifici di riferimento con destinazione d'uso non-residenziale. In particolare, si intende fornire profili tipo di domanda energetica per l'illuminazione artificiale, al fine di valutarne l'effetto sui profili di fabbisogno di energia per la climatizzazione estiva ed invernale, nonché di individuare le variabili che maggiormente incidono sulla loro determinazione. Per giungere a questi risultati, ci si avvale dell'uso di programmi informatici di simulazione dinamica riconosciuti ed impiegati a livello scientifico, in ambito europeo ed extraeuropeo (Energy Plus). La ricerca viene condotta sotto vari aspetti: architettonico, energetico e ambientale. Il primo obiettivo, partendo dalle indicazioni bibliografiche, legislative e normative, è quello di caratterizzare in modo univoco gli edifici di riferimento per le varie destinazioni d'uso oggetto di analisi: edifici per l'istruzione, ed edifici terziari. Gli edifici di riferimento intendono costituire archetipi rappresentativi del patrimonio edilizio italiano. Il secondo obiettivo è di tipo energetico: si intende definire profili tipo di domanda energetica per l'illuminazione artificiale degli ambienti. Si intendono inoltre valutare contestualmente i fabbisogni energetici netti per il riscaldamento e il raffrescamento degli ambienti. L'obiettivo finale è riuscire a determinare le migliori soluzioni progettuali per la minimizzazione del fabbisogno di energia connesso all'illuminazione, in relazione alle destinazioni d'uso dei differenti edifici, nonché le variabili che più incidono per indirizzare al meglio le attenzioni progettuali in caso di nuova realizzazione. Il presente lavoro, dopo un primo inquadramento generale in cui si delinea quello che è lo stato dell'arte della valutazione dei fabbisogni energetici e della ricerca scientifica in materia di illuminazione artificiale di ambienti non residenziali, passa poi ad indagare il significato di archetipo e a definire degli archetipi edilizi per il patrimonio immobiliare costruito a destinazione d'uso scolastica e terziaria. Successivamente vengono descritti i modelli di calcolo impiegati e sono dettagliati i dati di input impiegati per la loro definizione. Sono infine esplicati i risultati ottenuti, con individuazione dei valori di benchmark energetico per gli archetipi edilizi scolastici e terziari, e con l'analisi di quelle che sono le grandezze maggiormente influenti sul fabbisogno energetico per illuminazion
Production, characterization and determination of the real catalytic properties of the putative "succinate dehydrogenase" from Wolinella succinogenes
No full textBoth the genomes of the epsilonproteobacteria Wolinella succinogenes and Campylobacter jejuni contain operons (sdhABE) that encode for so far uncharacterized enzyme complexes annotated as ‘non-classical’ succinate:quinone reductases (SQRs). However, the role of such an enzyme ostensibly involved in aerobic respiration in an anaerobic organism such as W. succinogenes has hitherto been unknown. We have established the first genetic system for the manipulation and production of a member of the non-classical succinate:quinone oxidoreductase family. Biochemical characterization of the W. succinogenes enzyme reveals that the putative SQR is in fact a novel methylmenaquinol:fumarate reductase (MFR) with no detectable succinate oxidation activity, clearly indicative of its involvement in anaerobic metabolism. We demonstrate that the hydrophilic subunits of the MFR complex are, in contrast to all other previously characterized members of the superfamily, exported into the periplasm via the twin-arginine translocation (tat)-pathway. Furthermore we show that a single amino acid exchange (Ala86→His) in the flavoprotein of that enzyme complex is the only additional requirement for the covalent binding of the otherwise non-covalently bound FAD. Our results provide an explanation for the previously published puzzling observation that the C. jejuni sdhABE operon is upregulated in an oxygen-limited environment as compared with microaerophilic laboratory conditions
Evaluating the degree of difficulty of laparoscopic colorectal surgery
No full textObjective: To quantify the degree of overall difficulty and the difficulty of each of the individual steps involved in the performance of laparoscopic colorectal procedures. The data should serve as a guide to surgeons in the early stages of their experience in laparoscopic colorectal surgery as to which procedures and steps to embark on first, to allow them to build experience in a stepwise fashion. Methods: A mail-in survey of 35 experienced laparoscopic colorectal surgeons was conducted. Using a scale of 1 to 6, the surgeons were asked to rate the overall degree of difficulty of each of 12 laparoscopic colorectal procedures. Each procedure was then broken down into its key components (exposure, isolation of the vascular pedicle, dissection of the specimen, and anastomosis), and the raters were asked to individually grade each of these components for each intervention. An overall difficulty score was created for each procedure, as well as an individual difficulty score for each step. Results: The response rate was 80percent, representing a collective experience of approximately 6335 laparoscopic colorectal interventions. On the overall difficulty score, sigmoid colectomy achieved the lowest composite score of 2.0, while reversal of the Hartmann procedure scored the highest at 4.5. Analyzing the individual step complexity rating, mobilization of the splenic flexure scored highest, ahead of rectal mobilization. Vascular dissection scored significantly higher for right colectomy than for sigmoid resection, as did intracorporeal vs extracorporeal anastomosis for right colectomy. Conclusions: The learning curve for laparoscopic colorectal surgery is steep. This survey can help surgeons in the early part of this curve in their initial choice of procedure and allow them to build experience in a stepwise manner. This will help to identify achievable goals and develop strategies for reducing operating times and improving patient outcome by selecting appropriate cases at the outset. ©2008 American Medical Association. All rights reserved.Bennett CL, 1997, ARCH SURG-CHICAGO, V132, P41; BERMAN IR, 1992, DIS COLON RECTUM, V35, P689, DOI 10.1007-BF02053762; Chekan E G, 1999, Adv Surg, V32, P305; Nelson H, 2004, NEW ENGL J MED, V350, P2050; Cuschieri A, 1999, J ROY COLL SURG EDIN, V44, P187; GEIS WP, 1994, ARCH SURG-CHICAGO, V129, P206; Guillou PJ, 2005, LANCET, V365, P1718, DOI 10.1016-S0140-6736(05)66545-2; Leung KL, 2004, LANCET, V363, P1187, DOI 10.1016-S0140-6736(04)15947-3; Mancini F, 1999, Chirurgie, V124, P368, DOI 10.1016-S0001-4001(00)80008-2; MILLER R, 1992, BRIT J SURG, V79, P435, DOI 10.1002-bjs.1800790521; Nelson H, 2004, CANC TREAT REV, V30, P707; Reza MM, 2006, BRIT J SURG, V93, P921, DOI 10.1002-bjs.5430; Shah PR, 2005, POSTGRAD MED J, V81, P537, DOI 10.1136-pgmj.2004.028100; Smith CD, 1999, WORLD J SURG, V23, P389; Tekkis PP, 2005, ANN SURG, V242, P83, DOI 10.1097-01.sla.0000167857.14690.68; Veldkamp Ruben, 2005, Lancet Oncol, V6, P477; Young-Fadok TM, 2000, DIS COLON RECTUM, V43, P267, DOI 10.1007-BF0223699466666
Resolving Drivers of Microbial Community Structure in The Dry Valleys of Antarctica
No full textUnderstanding the processes that underlie patterns of microbial distribution is fundamental to the field of microbial ecology, but extremely challenging given the complexity of natural systems. Antarctica’s ice-free regions possess unique ecosystems of simple trophic structure, shaped by the harsh environmental conditions that typify the continent. The Dry Valleys comprise the largest of these regions and have one of the simplest food webs on the planet, making them a tractable system to comprehensively define relationships that influence microbial distributions at the landscape scale. The New Zealand Terrestrial Antarctic Biocomplexity Survey (nzTABS) was aimed at identifying factors that control, and can predict, biological distributions in the Dry Valleys. As part of nzTABS, the goal of the research presented in this thesis was to elucidate the factors that influence bacterial community structure in Dry Valley soils.
This study explored how topographic, physicochemical, and spatial variation influence bacterial diversity and community structure across a Dry Valley landscape. Bacterial communities were characterized in 471 soil samples using automated ribosomal intergenic spacer analysis (ARISA). Diversity and community composition were most strongly related to variation in physicochemical soil properties, though significant relationships with topographic and spatial variables were also observed. This identified, for the first time, the influence of environmental variables on bacterial diversity and community composition across the landscape, and presents a structural equation model identifying those relationships.
The phylogenetic diversity of bacterial communities in Dry Valley soils was also examined. High-throughput sequencing of 16S rRNA gene amplicons was used to analyze bacterial communities in 177 soil samples. This work identified significant relationships between the relative abundances of bacterial taxa and both abiotic and biotic variables, though these relationships explained only a small amount of community variation collectively. The relative abundances of several bacterial taxa were, however, significantly coupled to one another, suggesting that interactions between bacterial taxa may influence community compositions.
Lastly, the bacterial composition of aerosols above the Dry Valleys was examined. High-throughput sequencing of 16S rRNA gene amplicons was used to analyze two aerosol samples collected in the Miers Valley, and their compositions were compared to those of previously characterized aerosols and soils from across the continent. Bacteria present in the aerosols were found to be distinct from those of local soils; instead, aerosol compositions were more similar to those of air samples reported from elsewhere on the planet. Importantly, these findings suggest that local redistribution of Dry Valley soil bacteria through atmospheric processes may be largely restricted to periods when high winds mobilize soil particles and associated biota.
This study provides novel insights into the microbial ecology of the Dry Valleys. Despite the relative simplicity of the ecosystem, the factors that influence bacterial distributions within the Dry Valleys appear to be highly complex, and include a combination of abiotic and biotic drivers. Continued research will help to disentangle relationships that influence microbial community compositions in Antarctica’s ice-free ecosystems, and will improve understanding of processes that influence microbial community assembly globally
Mapping local patterns of childhood overweight and wasting in low- and middle-income countries between 2000 and 2017
Get PDFA double burden of malnutrition occurs when individuals, household members or communities experience both undernutrition and overweight. Here, we show geospatial estimates of overweight and wasting prevalence among children under 5 years of age in 105 low- and middle-income countries (LMICs) from 2000 to 2017 and aggregate these to policy-relevant administrative units. Wasting decreased overall across LMICs between 2000 and 2017, from 8.4 (62.3 (55.1–70.8) million) to 6.4 (58.3 (47.6–70.7) million), but is predicted to remain above the World Health Organization’s Global Nutrition Target of <5 in over half of LMICs by 2025. Prevalence of overweight increased from 5.2 (30 (22.8–38.5) million) in 2000 to 6.0 (55.5 (44.8–67.9) million) children aged under 5 years in 2017. Areas most affected by double burden of malnutrition were located in Indonesia, Thailand, southeastern China, Botswana, Cameroon and central Nigeria. Our estimates provide a new perspective to researchers, policy makers and public health agencies in their efforts to address this global childhood syndemic. © 2020, The Author(s)
Burden of HIV infection and HIV-associated morbidity in Zimbabwean adolescents
Get PDFThis thesis concerns the clinical epidemiology of HIV infection in Zimbabwean adolescents. Without treatment, there is a very high risk of death in the early years of life in HIV-infected infants. However, in recent years increasing numbers of adolescents have been presenting to health care services with symptomatic HIV infection and with features suggesting longstanding disease. Population-based surveys in Southern Africa have shown HIV prevalence rates among older children and adolescents to be much higher than would be anticipated if HIV-infants were not surviving early childhood. The burden and spectrum of HIV-associated morbidity among adolescents was investigated with two studies at secondary and primary care level, respectively. The main finding was of an extremely high prevalence of HIV infection at both levels of the health system, with HIV infection being the single most common cause of hospital admission and death among adolescents. Mother-to-child transmission was the most likely source of HIV infection in the majority, suggesting a substantial epidemic of older survivors of vertical HIV infection. Other countries with severe HIV epidemics may be experiencing a similar trend as their HIV epidemics mature. The lack of awareness of the possibility of survival to older childhood and adolescence with maternally-acquired, untreated HIV infection results in many missed opportunities for diagnosis, with HIV infection frequently not diagnosed until presentation with a severe HIV-related illness. The median CD4 count in 3 HIV-infected adolescents in primary care was 350cells/µl compared to a median CD4 count of 151cells/µl among hospitalised adolescents, suggesting that HIV testing in primary care identifies HIV-infected adolescents at an earlier stage of infection. Provider-initiated HIV testing and counselling in primary care was highly acceptable to adolescents and guardians. Provision of care has been adversely affected by under-appreciation of the numbers of surviving adolescents living with HIV, and the special needs of this age-group have not been distinguished from those of younger children. Young people who have acquired HIV perinatally are stigmatised by society who assume they must have acquired it through "bad" behaviour themselves, since it is not widely appreciated that long-term survival following vertical infection is possible. Immediate priorities are earlier diagnosis of HIV infection and improved management of HIV-infected adolescents. Possible areas of intervention are discussed in the final chapter. Similar studies are needed in neighbouring countries to investigate the generalisability of these findings
Outcomes for efavirenz versus nevirapine-containing regimens for treatment of HIV-1 infection: a systematic review and meta-analysis.
Get PDFINTRODUCTION: There is conflicting evidence and practice regarding the use of the non-nucleoside reverse transcriptase inhibitors (NNRTI) efavirenz (EFV) and nevirapine (NVP) in first-line antiretroviral therapy (ART). METHODS: We systematically reviewed virological outcomes in HIV-1 infected, treatment-naive patients on regimens containing EFV versus NVP from randomised trials and observational cohort studies. Data sources include PubMed, Embase, the Cochrane Central Register of Controlled Trials and conference proceedings of the International AIDS Society, Conference on Retroviruses and Opportunistic Infections, between 1996 to May 2013. Relative risks (RR) and 95% confidence intervals were synthesized using random-effects meta-analysis. Heterogeneity was assessed using the I(2) statistic, and subgroup analyses performed to assess the potential influence of study design, duration of follow up, location, and tuberculosis treatment. Sensitivity analyses explored the potential influence of different dosages of NVP and different viral load thresholds. RESULTS: Of 5011 citations retrieved, 38 reports of studies comprising 114 391 patients were included for review. EFV was significantly less likely than NVP to lead to virologic failure in both trials (RR 0.85 [0.73-0.99] I(2) = 0%) and observational studies (RR 0.65 [0.59-0.71] I(2) = 54%). EFV was more likely to achieve virologic success than NVP, though marginally significant, in both randomised controlled trials (RR 1.04 [1.00-1.08] I(2) = 0%) and observational studies (RR 1.06 [1.00-1.12] I(2) = 68%). CONCLUSION: EFV-based first line ART is significantly less likely to lead to virologic failure compared to NVP-based ART. This finding supports the use of EFV as the preferred NNRTI in first-line treatment regimen for HIV treatment, particularly in resource limited settings
Global age-sex-specific fertility, mortality, healthy life expectancy (HALE), and population estimates in 204 countries and territories, 1950–2019: a comprehensive demographic analysis for the Global Burden of Disease Study 2019
Get PDFBackground: Accurate and up-to-date assessment of demographic metrics is crucial for understanding a wide range of social, economic, and public health issues that affect populations worldwide. The Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2019 produced updated and comprehensive demographic assessments of the key indicators of fertility, mortality, migration, and population for 204 countries and territories and selected subnational locations from 1950 to 2019. Methods: 8078 country-years of vital registration and sample registration data, 938 surveys, 349 censuses, and 238 other sources were identified and used to estimate age-specific fertility. Spatiotemporal Gaussian process regression (ST-GPR) was used to generate age-specific fertility rates for 5-year age groups between ages 15 and 49 years. With extensions to age groups 10–14 and 50–54 years, the total fertility rate (TFR) was then aggregated using the estimated age-specific fertility between ages 10 and 54 years. 7417 sources were used for under-5 mortality estimation and 7355 for adult mortality. ST-GPR was used to synthesise data sources after correction for known biases. Adult mortality was measured as the probability of death between ages 15 and 60 years based on vital registration, sample registration, and sibling histories, and was also estimated using ST-GPR. HIV-free life tables were then estimated using estimates of under-5 and adult mortality rates using a relational model life table system created for GBD, which closely tracks observed age-specific mortality rates from complete vital registration when available. Independent estimates of HIV-specific mortality generated by an epidemiological analysis of HIV prevalence surveys and antenatal clinic serosurveillance and other sources were incorporated into the estimates in countries with large epidemics. Annual and single-year age estimates of net migration and population for each country and territory were generated using a Bayesian hierarchical cohort component model that analysed estimated age-specific fertility and mortality rates along with 1250 censuses and 747 population registry years. We classified location-years into seven categories on the basis of the natural rate of increase in population (calculated by subtracting the crude death rate from the crude birth rate) and the net migration rate. We computed healthy life expectancy (HALE) using years lived with disability (YLDs) per capita, life tables, and standard demographic methods. Uncertainty was propagated throughout the demographic estimation process, including fertility, mortality, and population, with 1000 draw-level estimates produced for each metric. Findings: The global TFR decreased from 2·72 (95 uncertainty interval UI 2·66–2·79) in 2000 to 2·31 (2·17–2·46) in 2019. Global annual livebirths increased from 134·5 million (131·5–137·8) in 2000 to a peak of 139·6 million (133·0–146·9) in 2016. Global livebirths then declined to 135·3 million (127·2–144·1) in 2019. Of the 204 countries and territories included in this study, in 2019, 102 had a TFR lower than 2·1, which is considered a good approximation of replacement-level fertility. All countries in sub-Saharan Africa had TFRs above replacement level in 2019 and accounted for 27·1% (95% UI 26·4–27·8) of global livebirths. Global life expectancy at birth increased from 67·2 years (95% UI 66·8–67·6) in 2000 to 73·5 years (72·8–74·3) in 2019. The total number of deaths increased from 50·7 million (49·5–51·9) in 2000 to 56·5 million (53·7–59·2) in 2019. Under-5 deaths declined from 9·6 million (9·1–10·3) in 2000 to 5·0 million (4·3–6·0) in 2019. Global population increased by 25·7%, from 6·2 billion (6·0–6·3) in 2000 to 7·7 billion (7·5–8·0) in 2019. In 2019, 34 countries had negative natural rates of increase; in 17 of these, the population declined because immigration was not sufficient to counteract the negative rate of decline. Globally, HALE increased from 58·6 years (56·1–60· ) in 2000 to 63·5 years (60·8–66·1) in 2019. HALE increased in 202 of 204 countries and territories between 2000 and 2019. Interpretation: Over the past 20 years, fertility rates have been dropping steadily and life expectancy has been increasing, with few exceptions. Much of this change follows historical patterns linking social and economic determinants, such as those captured by the GBD Socio-demographic Index, with demographic outcomes. More recently, several countries have experienced a combination of low fertility and stagnating improvement in mortality rates, pushing more populations into the late stages of the demographic transition. Tracking demographic change and the emergence of new patterns will be essential for global health monitoring. Funding: Bill & Melinda Gates Foundation. © 2020 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY 4.0 licens
