33 research outputs found
Structural behaviour of an innovative precast cold-formed steel ferrocement as composite beam
This research investigates the structural behaviour of simply supported composite beams, in which a ferrocement slab is connected together with cold-formed steel (CFS) beam by means of shear connectors. This system, called Precast Cold- Formed Steel-Ferrocement Composite Beam System, is designed to utilise the composite action between the CFS sections and ferrocement slab where shear forces are effectively transmitted between the beam and slab via shear connectors.CFS sections have been recognized as an important structural element in developed countries, and sustainable construction material for low rise residential and commercial buildings. However, it still is remains as insufficient data and information on the behaviour and performance of CFS as the composite construction in composite action is yet to be established. One limiting feature of CFS is the thickness of this section that makes it susceptible to torsional, distortional, lateral torsional, lateral distortional and local buckling. Hence, a reasonable solution is resorting composite construction of structural CFS section integrated with reinforced concrete deck slab. An efficient and innovative beam system of built-up CFS sections acting compositely with a concrete deck slab has been developed to provide an alternative composite system for floors and roofs in buildings. In this study, ferrocement is an alternative solution as concrete deck of a slab. It is a form of thin reinforced concrete structure, in which a strong cement-sand mortar matrix is reinforced with closely spaced, multiple layers of thin wire mesh or small diameter rods, uniformly dispersed throughout the matrix of the composite. This study mainly comprises three major components; experimental work, theoretical analysis and finite element analysis using ANSYS (version 11). Experimental works involved small-scale and full-scale testing of laboratory tests. The first phase of test program comprised often push-out test specimens and eighteen full-scale CFS-ferrocement composite beam specimens. Push-out tests were carried out to determine the strength and behaviour of the shear transfer enhancement between the CFS and ferrocement.Three types of shear connectors (bolts, self-drilling screws, bar angle) were tested and 2, 4 and 6 layers of wire mesh in ferrocement cold formed were proposed. The expression for predicting the capacity of shear connector in which bolt with 12mm diameter is best to be considered to transfer shear force into steel section-ferrocement slab interface. The second phase of test program comprised of a total of eighteen full-scale simply supported composite beams with variable parameters and tested to failure. The main variables considered in the study are the shape of section (I- and C-section as beam), thickness (2mm, 3mm and 4mm) of the CFS section and number of wire mesh layer (2, 4 and 6 layers). Four points load bending system was used to test the specimens. The plastic analysis results depicted that the ultimate bending capacity of a ferrocement CFS composite beam can be estimated by using conventional equilibrium procedures and the constitutive laws prescribed by Euro codes. The finite element and theoretical model showed agreement with the experimental results based on the moment versus deflection curves of the proposed composite beam system
Methods of financing waqf development in Singapore = أساليب تمويل تطوير األوقاف في سنغافورة
The Waqf sector in the Muslim world suffers in general from a state of negligence, and a lack of tactics and strategies in taking advantage of it, which results from cumulative and overlapping factors. This phenomenon invites for an investigation of successful Waqf experiences around the world, of which Singapore is the pioneer in it. The Waqf experience in Singapore is considered one of the most successful experiments at the
Muslim world level, both in terms of the organization, and the investment. The sector has witnessed a remarkable development as effective modern methods and techniques were discovered. The study aims to reveal the reality of this experience, which includes the following Waqf funds: funds for mosques, funds for the handicapped, Quran memorization, as well as education, scientific research, innovation and others. However, the monetary Waqf has gained popularity in the sector, unlike the Waqf of immovable assets. Muslims in Singapore have realized the importance of the monetary Waqf and its role in collecting social savings, converting them into social capital, and
developing the social capital market; to stimulate the merging between social security and social care, and to achieve the legitimate objectives of the Waqf and public interests. The Waqf administration in Singapore has used Sukuk to develop some of its endowments (Waqfs), therefore, the study will address how the Waqf in Singapore has benefited from this method in financing the development of endowments in both the construction project of a building on Beach Road 11, and a project to raise $ 35 million for the project to develop Waqf assets on Street Bencoolen. The researcher has employed both a case study as well as a descriptive analytical approach
Middle east respiratory syndrome coronavirus (MERS-CoV) RNA and neutralising antibodies in milk collected according to local customs from dromedary camels, Qatar, April 2014
Qatar experience on One Health approach for middle-east respiratory syndrome coronavirus, 2012-2017: A viewpoint
The emergence of the Middle East Respiratory Syndrome Corona Virus (MERS-CoV) in the Middle East in 2012
was associated with an overwhelming uncertainty about its epidemiological and clinical characteristics. Once
dromedary camels (Camelus dromedarius) was found to be the natural reservoir of the virus, the public health
systems across the Arabian Peninsula encountered an unprecedented pressure to control its transmission. This
view point describes how the One Health approach was used in Qatar to manage the MERS-CoV outbreak during
the period 2012–2017.
One Health focuses on the association between the human, animals and environment sectors for total health
and wellbeing of these three sectors. To manage the MERS outbreak in Qatar through a One Health approach, the
Qatar National Outbreak Control Taskforce (OCT) was reactivated in November 2012. The animal health sector
was invited to join the OCT. Later on, technical expertise was requested from the WHO, FAO, CDC, EMC, and
PHE. Subsequently, a comprehensive One Health roadmap was delivered through leadership and coordination;
surveillance and investigation; epidemiological studies and increase of local diagnostic capacity.
The joint OCT, once trained had easy access to allocated resources and high risk areas to provide more
evidence on the potential source of the virus and to investigate all reported cases within 24–48 h. Lack of
sufficient technical guidance on veterinary surveillance and poor risk perception among the vulnerable population constituted major obstacles to maintain systematic One Health performance
Middle East respiratory syndrome coronavirus in dromedary camels: An outbreak investigation
Background: Middle East respiratory syndrome coronavirus (MERS-CoV) causes severe lower respiratory tract infection in people. Previous studies suggested dromedary camels were a reservoir for this virus. We tested for the presence of MERS-CoV in dromedary camels from a farm in Qatar linked to two human cases of the infection in October, 2013. Methods: We took nose swabs, rectal swabs, and blood samples from all camels on the Qatari farm. We tested swabs with RT-PCR, with amplification targeting the E gene (upE), nucleocapsid (N) gene, and open reading frame (ORF) 1a. PCR positive samples were tested by different MERS-CoV specific PCRs and obtained sequences were used for phylogentic analysis together with sequences from the linked human cases and other human cases. We tested serum samples from the camels for IgG immunofluorescence assay, protein microarray, and virus neutralisation assay. Findings: We obtained samples from 14 camels on Oct 17, 2013. We detected MERS-CoV in nose swabs from three camels by three independent RT-PCRs and sequencing. The nucleotide sequence of an ORF1a fragment (940 nucleotides) and a 4·2 kb concatenated fragment were very similar to the MERS-CoV from two human cases on the same farm and a MERS-CoV isolate from Hafr-Al-Batin. Eight additional camel nose swabs were positive on one or more RT-PCRs, but could not be confirmed by sequencing. All camels had MERS-CoV spike-binding antibodies that correlated well with the presence of neutralising antibodies to MERS-CoV. Interpretation: Our study provides virological confirmation of MERS-CoV in camels and suggests a recent outbreak affecting both human beings and camels. We cannot conclude whether the people on the farm were infected by the camels or vice versa, or if a third source was responsible. Funding: European Union projects EMPERIE (contract number 223498), ANTIGONE (contract number 278976), and the VIRGO consortium
The sample of choice for detecting Middle East respiratory syndrome coronavirus in asymptomatic dromedary camels using real-time reverse-transcription polymerase chain reaction
The newly identified Middle East respiratory syndrome coronavirus (MERS-CoV), which causes severe respiratory disease, particularly in people with comorbidities, requires further investigation. Studies in Qatar and elsewhere have provided evidence that dromedary camels are a reservoir for the virus, but the exact modes of transmission of MERS-CoV to humans remain unclear. In February 2014, an assessment was made of the suitability and sensitivity of different types of sample for the detection of MERS-CoV by real-time reverse-transcription polymerase chain reaction (RT-PCR) for three gene targets: UpE (upstream of the E gene), the N (nucleocapsid) gene and open reading frame (ORF) 1a. Fifty-three animals presented for slaughter were sampled. A high percentage of the sampled camels (79% [95% confidence interval 66.9-91.5%, standard error 0.0625]; 42 out of 53) were shown to be shedding MERS-CoV at the time of slaughter, yet all the animals were apparently healthy. Among the virus-positive animals, nasal swabs were most often positive (97.6%). Oral swabs were the second most frequently positive (35.7%), followed by rectal swabs (28.5%). In addition, the highest viral load, expressed as a cycle threshold (Ct) value of 11.27, was obtained from a nasal swab. These findings lead to the conclusion that nasal swabs are the candidate sample of choice for detecting MERS-CoV using RT-PCR technology in apparently healthy camels
Occupational exposure to dromedaries and risk for MERS-CoV infection, Qatar, 2013–2014
We determined the presence of neutralizing antibodies to Middle East respiratory syndrome coronavirus in persons in Qatar with and without dromedary contact. Antibodies were only detected in those with contact, suggesting dromedary exposure as a risk factor for infection. Findings also showed evidence for substantial underestimation of the infection in populations at risk in Qatar
Isolation of MERS coronavirus from dromedary camel, Qatar, 2014
We obtained the full genome of Middle East respiratory syndrome coronavirus (MERS-CoV) from a camel in Qatar. This virus is highly similar to the human England/ Qatar 1 virus isolated in 2012. The MERS-CoV from the camel efficiently replicated in human cells, providing further evidence for the zoonotic potential of MERS-CoV from camels
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Global fertility in 204 countries and territories, 1950–2021, with forecasts to 2100: a comprehensive demographic analysis for the Global Burden of Disease Study 2021
Background
Accurate assessments of current and future fertility—including overall trends and changing population age structures across countries and regions—are essential to help plan for the profound social, economic, environmental, and geopolitical challenges that these changes will bring. Estimates and projections of fertility are necessary to inform policies involving resource and health-care needs, labour supply, education, gender equality, and family planning and support. The Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2021 produced up-to-date and comprehensive demographic assessments of key fertility indicators at global, regional, and national levels from 1950 to 2021 and forecast fertility metrics to 2100 based on a reference scenario and key policy-dependent alternative scenarios.
Methods
To estimate fertility indicators from 1950 to 2021, mixed-effects regression models and spatiotemporal Gaussian process regression were used to synthesise data from 8709 country-years of vital and sample registrations, 1455 surveys and censuses, and 150 other sources, and to generate age-specific fertility rates (ASFRs) for 5-year age groups from age 10 years to 54 years. ASFRs were summed across age groups to produce estimates of total fertility rate (TFR). Livebirths were calculated by multiplying ASFR and age-specific female population, then summing across ages 10–54 years. To forecast future fertility up to 2100, our Institute for Health Metrics and Evaluation (IHME) forecasting model was based on projections of completed cohort fertility at age 50 years (CCF50; the average number of children born over time to females from a specified birth cohort), which yields more stable and accurate measures of fertility than directly modelling TFR. CCF50 was modelled using an ensemble approach in which three sub-models (with two, three, and four covariates variously consisting of female educational attainment, contraceptive met need, population density in habitable areas, and under-5 mortality) were given equal weights, and analyses were conducted utilising the MR-BRT (meta-regression—Bayesian, regularised, trimmed) tool. To capture time-series trends in CCF50 not explained by these covariates, we used a first-order autoregressive model on the residual term. CCF50 as a proportion of each 5-year ASFR was predicted using a linear mixed-effects model with fixed-effects covariates (female educational attainment and contraceptive met need) and random intercepts for geographical regions. Projected TFRs were then computed for each calendar year as the sum of single-year ASFRs across age groups. The reference forecast is our estimate of the most likely fertility future given the model, past fertility, forecasts of covariates, and historical relationships between covariates and fertility. We additionally produced forecasts for multiple alternative scenarios in each location: the UN Sustainable Development Goal (SDG) for education is achieved by 2030; the contraceptive met need SDG is achieved by 2030; pro-natal policies are enacted to create supportive environments for those who give birth; and the previous three scenarios combined. Uncertainty from past data inputs and model estimation was propagated throughout analyses by taking 1000 draws for past and present fertility estimates and 500 draws for future forecasts from the estimated distribution for each metric, with 95% uncertainty intervals (UIs) given as the 2·5 and 97·5 percentiles of the draws. To evaluate the forecasting performance of our model and others, we computed skill values—a metric assessing gain in forecasting accuracy—by comparing predicted versus observed ASFRs from the past 15 years (2007–21). A positive skill metric indicates that the model being evaluated performs better than the baseline model (here, a simplified model holding 2007 values constant in the future), and a negative metric indicates that the evaluated model performs worse than baseline.
Findings
During the period from 1950 to 2021, global TFR more than halved, from 4·84 (95% UI 4·63–5·06) to 2·23 (2·09–2·38). Global annual livebirths peaked in 2016 at 142 million (95% UI 137–147), declining to 129 million (121–138) in 2021. Fertility rates declined in all countries and territories since 1950, with TFR remaining above 2·1—canonically considered replacement-level fertility—in 94 (46·1%) countries and territories in 2021. This included 44 of 46 countries in sub-Saharan Africa, which was the super-region with the largest share of livebirths in 2021 (29·2% [28·7–29·6]). 47 countries and territories in which lowest estimated fertility between 1950 and 2021 was below replacement experienced one or more subsequent years with higher fertility; only three of these locations rebounded above replacement levels. Future fertility rates were projected to continue to decline worldwide, reaching a global TFR of 1·83 (1·59–2·08) in 2050 and 1·59 (1·25–1·96) in 2100 under the reference scenario. The number of countries and territories with fertility rates remaining above replacement was forecast to be 49 (24·0%) in 2050 and only six (2·9%) in 2100, with three of these six countries included in the 2021 World Bank-defined low-income group, all located in the GBD super-region of sub-Saharan Africa. The proportion of livebirths occurring in sub-Saharan Africa was forecast to increase to more than half of the world's livebirths in 2100, to 41·3% (39·6–43·1) in 2050 and 54·3% (47·1–59·5) in 2100. The share of livebirths was projected to decline between 2021 and 2100 in most of the six other super-regions—decreasing, for example, in south Asia from 24·8% (23·7–25·8) in 2021 to 16·7% (14·3–19·1) in 2050 and 7·1% (4·4–10·1) in 2100—but was forecast to increase modestly in the north Africa and Middle East and high-income super-regions. Forecast estimates for the alternative combined scenario suggest that meeting SDG targets for education and contraceptive met need, as well as implementing pro-natal policies, would result in global TFRs of 1·65 (1·40–1·92) in 2050 and 1·62 (1·35–1·95) in 2100. The forecasting skill metric values for the IHME model were positive across all age groups, indicating that the model is better than the constant prediction.
Interpretation
Fertility is declining globally, with rates in more than half of all countries and territories in 2021 below replacement level. Trends since 2000 show considerable heterogeneity in the steepness of declines, and only a small number of countries experienced even a slight fertility rebound after their lowest observed rate, with none reaching replacement level. Additionally, the distribution of livebirths across the globe is shifting, with a greater proportion occurring in the lowest-income countries. Future fertility rates will continue to decline worldwide and will remain low even under successful implementation of pro-natal policies. These changes will have far-reaching economic and societal consequences due to ageing populations and declining workforces in higher-income countries, combined with an increasing share of livebirths among the already poorest regions of the world