48 research outputs found
Dielectric properties of (CuO,CaO₂, and BaO)y/CuTl-1223 composites
We synthesized (CuO, CaO₂, and BaO)y/Cu₀,₅Tl₀,₅Ba₂Ca₂Cu₃O₁₀–δ (y = 0, 5%, 10%, 15%) composites by solid-state reaction and characterized by x-ray diffraction, scanning electron microscopy, dc-resistivity, and Fourier transform infrared spectroscopy. Frequency and temperature dependent dielectric properties such as real and imag-inary part of dielectric constant, dielectric loss, and ac-conductivity of these composites are studied by capacitance and conductance measurement as a function of frequency (10 kHz to 10 MHz) and temperature (78 to 300 K). The x-ray diffraction analysis reveals that the characteristic behavior of Cu₀,₅Tl₀,₅Ba₂Ca₂Cu₃O₁₀–δ supercon-ductor phase and its structure is nearly undisturbed by doping of nanoparticles. The scanning electron microsco-py images show the improvement in the intergranular links among the superconducting grains with increasing nanoparticles concentration. Microcracks are healed up with the inclusion of these nanoparticles and superconduct-ing volume fraction is also increased. The dielectric properties of these composites strongly depend upon the fre-quency and temperature. The zero resistivity critical temperature and dielectric properties show opposite trend with the addition of nanoparticles in Cu₀,₅Tl₀,₅Ba₂Ca₂Cu₃O₁₀–δ superconductor matrix
Fabrication and Characterization of a W-Band Cylindrical Dielectric Resonator Antenna-Coupled Niobium Microbolometer
We report on the fabrication and characterization of a novel antenna-coupled detector configuration for detection at 94 GHz, a coplanar waveguide- (CPW-) fed, slot-excited twin dielectric resonator antenna- (DRA-) coupled niobium (Nb) microbolometer. The antenna is based on two low permittivity cylindrical dielectric resonators (CDRs) excited by rectangular slots placed below the CDRs. The antenna resonant currents are fed to an Nb microbolometer by the means of a CPW feed. The ceramic DRA structure is manufactured using a novel fabrication process that enables patterning an SU-8–Alumina (Al2O3) nanopowder composite using conventional photolithography. The detector measured a voltage responsivity of 0.181 V/W at a modulation frequency of 150 Hz. The detector measured a time constant of 1.94 μs. The antenna radiation pattern of the developed detector configuration was measured and shows a good agreement with the simulation
The Karachi intracranial stenosis study (KISS) Protocol: an urban multicenter case-control investigation reporting the clinical, radiologic and biochemical associations of intracranial stenosis in Pakistan.
Background: Intracranial stenosis is the most common cause of stroke among Asians. It has a poor prognosis with a high rate of recurrence. No effective medical or surgical treatment modality has been developed for the treatment of stroke due to intracranial stenosis. We aim to identify risk factors and biomarkers for intracranial stenosis and to develop techniques such as use of transcranial doppler to help diagnose intracranial stenosis in a cost-effective manner.
Methods/Design: The Karachi Intracranial Stenosis Study (KISS) is a prospective, observational, case-control study to describe the clinical features and determine the risk factors of patients with stroke due to intracranial stenosis and compare them to those with stroke due to other etiologies as well as to unaffected individuals. We plan to recruit 200 patients with stroke due to intracranial stenosis and two control groups each of 150 matched individuals. The first set of controls will include patients with ischemic stroke that is due to other atherosclerotic mechanisms specifically lacunar and cardioembolic strokes. The second group will consist of stroke free individuals. Standardized interviews will be conducted to determine demographic, medical, social, and behavioral variables along with baseline medications. Mandatory procedures for inclusion in the study are clinical confirmation of stroke by a healthcare professional within 72 hours of onset, 12 lead electrocardiogram, and neuroimaging. In addition, lipid profile, serum glucose, creatinine and HbA1C will be measured in all participants. Ancillary tests will include carotid ultrasound, transcranial doppler and magnetic resonance or computed tomography angiogram to rule out concurrent carotid disease. Echocardiogram and other additional investigations will be performed at these centers at the discretion of the regional physicians.
Discussion: The results of this study will help inform locally relevant clinical guidelines and effective public health and individual interventions
Assessment of sublethal and transgenerational effects of spirotetramat, on population growth of cabbage aphid, Brevicoryne brassicae L. (Hemiptera: Aphididae)
The cabbage aphid (Brevicoryne brassicae L.) is a devastating pest of cruciferous crops causing economic damage worldwide and notably owing to its increasing resistance to commonly used pesticides. Such resistance prompts the development of integrated pest management (IPM) programs that include novel pesticides being effective against the aphids. Spirotetramat is a novel insecticide used against sap-sucking insect pests, particularly aphids. This study evaluated the toxicity of spirotetramat to adult apterous B. brassicae after 72 h using the leaf dipping method. According to the toxicity bioassay results, the LC50 value of spirotetramat to B. brassicae was 1.304 mgL−1. However, the sublethal concentrations (LC5 and LC15) and transgenerational effects of this novel insecticide on population growth parameters were estimated using the age-stage, two-sex life table theory method. The sublethal concentrations (LC5; 0.125 mgL−1 and LC15; 0.298 mgL−1) of spirotetramat reduced the adult longevity and fecundity of the parent generation (F0). These concentrations prolonged the preadult developmental duration while decreasing preadult survival, adult longevity and reproduction of the F1 generation. The adult pre-reproductive period was also extended by spirotetramat treatment groups. Subsequently, the population growth parameters such as the intrinsic rate of increase r, finite rate of increase λ and net reproductive rate R0 of the F1 generation were decreased in spirotetramat treatment groups whereas, the mean generation time T of the F1 generation was not affected when compared to the control. These results indicated the negative effect of sublethal concentrations of spirotetramat on the performance of B. brassicae by reducing its nymphal survival, extending the duration of some immature stages and suppressing the population growth of B. brassicae. Overall, we demonstrated that spirotetramat is a pesticide showing both sublethal activities, and transgenerational effects on cabbage aphid; it may be useful for implementation in IPM programs against this aphid pest
Ongoing strategies to improve antimicrobial utilization in hospitals across the Middle East and North Africa (MENA) : findings and implications
Antimicrobial resistance (AMR) is an increasing global concern, increasing costs, morbidity, and mortality. National action plans (NAPs) to minimize AMR are one of several global and national initiatives to slow down rising AMR rates. NAPs are also helping key stakeholders understand current antimicrobial utilization patterns and resistance rates. The Middle East is no exception with high AMR rates. Antibiotic point prevalence surveys (PPS) provide a better understanding of existing antimicrobial consumption trends in hospitals, and assist with the subsequent imple-mentation of antimicrobial stewardship programs (ASPs). These are important NAP activities. We examined current hospital consumption trends across the Middle East along with documented ASPs. A narrative assessment of 24 PPS studies in the Region found that, on average, more than 50% of in-patients received antibiotics, with Jordan having the highest rate at 98.1%. Published studies ranged in size from single to 18 hospitals. The most prescribed antibiotics were ceftriax-one, metronidazole, and penicillin. In addition, significant postoperative antibiotic prescribing lasting up to five days or longer was common to avoid surgical site infections. These findings have resulted in a variety of suggested short-, medium-, and long-term actions among key stakehold-ers, including governments and healthcare workers, to improve and sustain future antibiotic prescribing in order to decrease AMR throughout the Middle East
Global incidence, prevalence, years lived with disability (YLDs), disability-adjusted life-years (DALYs), and healthy life expectancy (HALE) for 371 diseases and injuries in 204 countries and territories and 811 subnational locations, 1990–2021: a systematic analysis for the Global Burden of Disease Study 2021
Background: Detailed, comprehensive, and timely reporting on population health by underlying causes of disability and premature death is crucial to understanding and responding to complex patterns of disease and injury burden over time and across age groups, sexes, and locations. The availability of disease burden estimates can promote evidence-based interventions that enable public health researchers, policy makers, and other professionals to implement strategies that can mitigate diseases. It can also facilitate more rigorous monitoring of progress towards national and international health targets, such as the Sustainable Development Goals. For three decades, the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) has filled that need. A global network of collaborators contributed to the production of GBD 2021 by providing, reviewing, and analysing all available data. GBD estimates are updated routinely with additional data and refined analytical methods. GBD 2021 presents, for the first time, estimates of health loss due to the COVID-19 pandemic. Methods: The GBD 2021 disease and injury burden analysis estimated years lived with disability (YLDs), years of life lost (YLLs), disability-adjusted life-years (DALYs), and healthy life expectancy (HALE) for 371 diseases and injuries using 100 983 data sources. Data were extracted from vital registration systems, verbal autopsies, censuses, household surveys, disease-specific registries, health service contact data, and other sources. YLDs were calculated by multiplying cause-age-sex-location-year-specific prevalence of sequelae by their respective disability weights, for each disease and injury. YLLs were calculated by multiplying cause-age-sex-location-year-specific deaths by the standard life expectancy at the age that death occurred. DALYs were calculated by summing YLDs and YLLs. HALE estimates were produced using YLDs per capita and age-specific mortality rates by location, age, sex, year, and cause. 95% uncertainty intervals (UIs) were generated for all final estimates as the 2·5th and 97·5th percentiles values of 500 draws. Uncertainty was propagated at each step of the estimation process. Counts and age-standardised rates were calculated globally, for seven super-regions, 21 regions, 204 countries and territories (including 21 countries with subnational locations), and 811 subnational locations, from 1990 to 2021. Here we report data for 2010 to 2021 to highlight trends in disease burden over the past decade and through the first 2 years of the COVID-19 pandemic. Findings: Global DALYs increased from 2·63 billion (95% UI 2·44–2·85) in 2010 to 2·88 billion (2·64–3·15) in 2021 for all causes combined. Much of this increase in the number of DALYs was due to population growth and ageing, as indicated by a decrease in global age-standardised all-cause DALY rates of 14·2% (95% UI 10·7–17·3) between 2010 and 2019. Notably, however, this decrease in rates reversed during the first 2 years of the COVID-19 pandemic, with increases in global age-standardised all-cause DALY rates since 2019 of 4·1% (1·8–6·3) in 2020 and 7·2% (4·7–10·0) in 2021. In 2021, COVID-19 was the leading cause of DALYs globally (212·0 million [198·0–234·5] DALYs), followed by ischaemic heart disease (188·3 million [176·7–198·3]), neonatal disorders (186·3 million [162·3–214·9]), and stroke (160·4 million [148·0–171·7]). However, notable health gains were seen among other leading communicable, maternal, neonatal, and nutritional (CMNN) diseases. Globally between 2010 and 2021, the age-standardised DALY rates for HIV/AIDS decreased by 47·8% (43·3–51·7) and for diarrhoeal diseases decreased by 47·0% (39·9–52·9). Non-communicable diseases contributed 1·73 billion (95% UI 1·54–1·94) DALYs in 2021, with a decrease in age-standardised DALY rates since 2010 of 6·4% (95% UI 3·5–9·5). Between 2010 and 2021, among the 25 leading Level 3 causes, age-standardised DALY rates increased most substantially for anxiety disorders (16·7% [14·0–19·8]), depressive disorders (16·4% [11·9–21·3]), and diabetes (14·0% [10·0–17·4]). Age-standardised DALY rates due to injuries decreased globally by 24·0% (20·7–27·2) between 2010 and 2021, although improvements were not uniform across locations, ages, and sexes. Globally, HALE at birth improved slightly, from 61·3 years (58·6–63·6) in 2010 to 62·2 years (59·4–64·7) in 2021. However, despite this overall increase, HALE decreased by 2·2% (1·6–2·9) between 2019 and 2021. Interpretation: Putting the COVID-19 pandemic in the context of a mutually exclusive and collectively exhaustive list of causes of health loss is crucial to understanding its impact and ensuring that health funding and policy address needs at both local and global levels through cost-effective and evidence-based interventions. A global epidemiological transition remains underway. Our findings suggest that prioritising non-communicable disease prevention and treatment policies, as well as strengthening health systems, continues to be crucially important. The progress on reducing the burden of CMNN diseases must not stall; although global trends are improving, the burden of CMNN diseases remains unacceptably high. Evidence-based interventions will help save the lives of young children and mothers and improve the overall health and economic conditions of societies across the world. Governments and multilateral organisations should prioritise pandemic preparedness planning alongside efforts to reduce the burden of diseases and injuries that will strain resources in the coming decades. Funding: Bill & Melinda Gates Foundation