National University of Science and Technology

OBJECTIVES: To estimate COVID-19 infections and deaths in healthcare workers (HCWs) from a global perspective during the early phases of the pandemic. DESIGN: Systematic review. METHODS: Two parallel searches of academic bibliographic databases and grey literature were undertaken until 8 May 2020. Governments were also contacted for further information where possible. There were no restrictions on language, information sources used, publication status and types of sources of evidence. The AACODS checklist or the National Institutes of Health study quality assessment tools were used to appraise each source of evidence. OUTCOME MEASURES: Publication characteristics, country-specific data points, COVID-19-specific data, demographics of affected HCWs and public health measures employed. RESULTS: A total of 152 888 infections and 1413 deaths were reported. Infections were mainly in women (71.6%, n=14 058) and nurses (38.6%, n=10 706), but deaths were mainly in men (70.8%, n=550) and doctors (51.4%, n=525). Limited data suggested that general practitioners and mental health nurses were the highest risk specialities for deaths. There were 37.2 deaths reported per 100 infections for HCWs aged over 70 years. Europe had the highest absolute numbers of reported infections (119 628) and deaths (712), but the Eastern Mediterranean region had the highest number of reported deaths per 100 infections (5.7). CONCLUSIONS: COVID-19 infections and deaths among HCWs follow that of the general population around the world. The reasons for gender and specialty differences require further exploration, as do the low rates reported in Africa and India. Although physicians working in certain specialities may be considered high risk due to exposure to oronasal secretions, the risk to other specialities must not be underestimated. Elderly HCWs may require assigning to less risky settings such as telemedicine or administrative positions. Our pragmatic approach provides general trends, and highlights the need for universal guidelines for testing and reporting of infections in HCWs.

This article describes a very different approach to the decentralized compression of networked data. Considering a particularly salient aspect of this struggle that revolves around large-scale distributed sources of data and their storage, transmission, and retrieval. The task of transmitting information from one point to another is a common and well-understood exercise. But the problem of efficiently transmitting or sharing information from and among a vast number of distributed nodes remains a great challenge, primarily because we do not yet have well developed theories and tools for distributed signal processing, communications, and information theory in large-scale networked systems.

Compressive sensing (CS) is a novel sampling paradigm that samples signals in a much more efficient way than the established Nyquist sampling theorem. CS has recently gained a lot of attention due to its exploitation of signal sparsity. Sparsity, an inherent characteristic of many natural signals, enables the signal to be stored in few samples and subsequently be recovered accurately, courtesy of CS. This article gives a brief background on the origins of this idea, reviews the basic mathematical foundation of the theory and then goes on to highlight different areas of its application with a major emphasis on communications and network domain. Finally, the survey concludes by identifying new areas of research where CS could be beneficial.

In this paper, magnetohydrodynamic (MHD) Casson fluid flow in two lateral directions past a porous linear stretching sheet is investigated. Self-similar solutions are obtained and compared with the available data for special cases. It is found that the present results are in an excellent agreement with the available data. The dimensionless velocities and shear stresses are obtained in both directions. Pertinent results are presented graphically and discussed quantitatively with respect to variation in Casson flow parameter as well as other fluid flow parameters.

Judgement of quality in qualitative has been a contested and controversial issue amongst researchers. Contention has always emanated from the subjective nature of qualitative studies, absence of clear guidelines in sampling as well as the lack of generalisability of findings. Numerous avenues have been suggested to improve qualitative research quality and key amongst the suggestions is the concept of saturation. It is viewed as a contemporary measure to alleviate the subjectivity in qualitative research, a yardstick for estimating sample sizes in qualitative research as well as an assurance for rigour and quality. Despite its recognition as a vital tool, it has its own fair share of controversies and contradictions. This research, through a comprehensive and evaluative literature review sought to unpack the saturation puzzle, controversies in definitions and underlying assumptions. The objective was to make a contribution to the contemporary but growing body of knowledge on the saturation conundrum. The study found out that there are various forms of saturation and with varying underlying propositions, therefore in order to meaningfully apply the concept, researchers have to appreciate the forms of saturation, link the appropriate form to their qualitative research design. It is undoubtedly important for research to define fully the form adopted, explicate the steps followed to achieve it and how it was ultimately achieved. In short, narrow the scope of saturation and contextualise it to your research.

Crack is a common form of pavement distress and it carries significant information on the condition of roads. The detection of cracks is essential to perform pavement maintenance and rehabilitation. Many of the highways agencies, in different countries, are still employing conventional, costly and very time consuming techniques which involve direct human intervention and assessment. Although automated recognition has been successfully performed for many pavement distresses, crack detection remains, to this date, a topic where reservations exist. A novel approach to automatically distinguish cracks in digital pavement images is proposed in this paper. The Gabor filter is proven to be a highly potential technique for multidirectional crack detection that was not done previously using the Gabor filter. Image analysis using the Gabor function is directly related to the mammalian visual perception, hence the choice of this method for crack detection. Results reported in this paper concentrate on pavement images with high levels of surface texture that makes crack detection difficult. An initial detection precision of up to 95% has been reported in this paper showing a good promise in the proposed method.

The presented review summarizes nearly two decades of studies on femtosecond laser-induced breakdown spectrometry (fs-LIBS).

The strong bonding in wide bandgap semiconductors gives them an intrinsic radiation hardness.

BACKGROUND: There is an urgent need to understand how the provision of information influences individual risk perception and how this in turn shapes the evolution of epidemics. Individuals are influenced by information in complex and unpredictable ways. Emerging infectious diseases, such as the recent swine flu epidemic, may be particular hotspots for a media-fueled rush to vaccination; conversely, seasonal diseases may receive little media attention, despite their high mortality rate, due to their perceived lack of newness. METHODS: We formulate a deterministic transmission and vaccination model to investigate the effects of media coverage on the transmission dynamics of influenza. The population is subdivided into different classes according to their disease status. The compartmental model includes the effect of media coverage on reporting the number of infections as well as the number of individuals successfully vaccinated. RESULTS: A threshold parameter (the basic reproductive ratio) is analytically derived and used to discuss the local stability of the disease-free steady state. The impact of costs that can be incurred, which include vaccination, education, implementation and campaigns on media coverage, are also investigated using optimal control theory. A simplified version of the model with pulse vaccination shows that the media can trigger a vaccinating panic if the vaccine is imperfect and simplified messages result in the vaccinated mixing with the infectives without regard to disease risk. CONCLUSIONS: The effects of media on an outbreak are complex. Simplified understandings of disease epidemiology, propogated through media soundbites, may make the disease significantly worse.

Preliminary concepts and background replacement policies with minimal repairs problems with applications to computing systems software reliability growth models based on NHPP release policies numerical computations in renewal and reliability theory.

(2004). Tangible and Intangible Heritage: from difference to convergence. Museum International: Vol. 56, No. 1-2, pp. 12-20.

Colloidal gold nanoparticles (AuNPs) are of interest as non-toxic carriers for drug delivery owing to their advanced properties, such as extensive surface-to-volume ratio and possibilities for tailoring their charge, hydrophilicity and functionality through surface chemistries. To date, various biocompatible polymers have been used for surface decoration of AuNPs to enhance their stability, payloads capacity and cellular uptake. This study describes a facile one-step method to synthesize stable AuNPs loaded with combination of two anticancer therapeutics, -bleomycin and doxorubicin. Anticancer activities, cytotoxicity, uptake and intracellular localization of the AuNPs were demonstrated in HeLa cells. We show that the therapeutic efficacy of the nanohybrid drug was strongly enhanced by the active targeting by the nanoscale delivery system to HeLa cells with a significant decrease of the half-maximal effective drug concentration, through blockage of HeLa cancer cell cycle. These results provide rationale for further progress of AuNPs-assisted combination chemotherapy using two drugs at optimized effective concentrations which act via different mechanisms thus decreasing possibilities of development of the cancer drug resistance, reduction of systemic drug toxicity and improvement of outcomes of chemotherapy.

An ultrahigh enhancement rate of <italic>U</italic>_d (≈187%) and <italic>U</italic>_d (≈19 J cm⁻³) have been obtained for P(VDF-HFP)-based nanocomposites using novel core–shell BaTiO₃@MgO as the filler.

The mechanism of structural transformation during combustion of nickel nitrate (oxidizer)–glycine (fuel) system is investigated by using different in situ techniques, including time-resolved X-ray diffraction (TRXRD), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) with dynamic mass spectrometry (MS), and high-speed infrared thermal imaging. It is shown that for initial compositions with a relatively large fuel-to-oxidizer ratio (φ), pure Ni phase forms directly in the combustion front. For fuel-lean conditions, only NiO phase can be detected. Analysis of the obtained data, including transmission and scanning electron microscopy (TEM–SEM) studies of the quenched reaction fronts, allows us to suggest the intrinsic mechanism of pure metal formation in the investigated system. It is shown that the combustion front propagates because of the reaction between N2O and NH3, which are the products of decomposition of the oxidizer and fuel. The excess of NH3 gas produced in fuel-rich conditions rapidly (<0.2 s) reduces nickel oxide to pure metal in the reaction front.

Steady flow of a Casson fluid in the presence of a nanoparticle is studied. It is considered that the sheet is stretched in both the direction along the xy-plane. Moreover, we have considered the magnetohydrodynamics effect within the fluid and convective condition along the surface. Similarity transformation is used to convert the governing partial differential equations to a set of coupled nonlinear ordinary differential equations which are solved numerically. The behavior of emerging parameters are presented graphically and discussed for velocity, temperature, and nanoparticles fraction. Variation of the reduced Nusselt and Sherwood number against physical parameters are presented graphically. It is found that the reduced Nusselt number is the decreasing function and the reduced Sherwood number is the increasing function of Brownian parameter Nb and thermophoresis parameter Nt.

superexchange interactions. The behavior of the amplitude-frequency characteristics is largely determined through the reduction of uniaxial exchange anisotropy. The prospects of Ga-substituted hexaferrites acting as a material that effectively absorbs the high-frequency electromagnetic radiation are shown.

Abstract. The management of agroecosystems plays a crucial role in the global carbon cycle with soil tillage leading to known organic carbon redistributions within soils and changes in soil CO2 emissions. Yet, discrepancies exist on the impact of tillage on soil CO2 emissions and on the main soil and environmental controls. A meta-analysis was conducted using 46 peer-reviewed publications totaling 174 paired observations comparing CO2 emissions over entire seasons or years from tilled and untilled soils across different climates, crop types and soil conditions with the objective of quantifying tillage impact on CO2 emissions and assessing the main controls. On average, tilled soils emitted 21 % more CO2 than untilled soils, which corresponded to a significant difference at P&lt;0.05. The difference increased to 29 % in sandy soils from arid climates with low soil organic carbon content (SOCC &lt; 1 %) and low soil moisture, but tillage had no impact on CO2 fluxes in clayey soils with high background SOCC (&gt; 3 %). Finally, nitrogen fertilization and crop residue management had little effect on the CO2 responses of soils to no-tillage. These results suggest no-tillage is an effective mitigation measure of carbon dioxide losses from dry land soils. They emphasize the importance of including information on soil factors such as texture, aggregate stability and organic carbon content in global models of the carbon cycle.

The LTMN_0.25 + 1 wt% 0.6CuO–0.4B₂O₃ ceramic with low sintering temperature, small density and excellent performance have wide application prospects in 5G devices.

A deterministic model for the co-interaction of HIV and malaria in a community is presented and rigorously analyzed. Two sub-models, namely the <i>HIV-only</i> and <i> malaria-only</i> sub-models, are considered first of all. Unlike the HIV-only sub-model, which has a globally-asymptotically stable disease-free equilibrium whenever the associated reproduction number is less than unity, the malaria-only sub-model undergoes the phenomenon of backward bifurcation, where a stable disease-free equilibrium co-exists with a stable endemic equilibrium, for a certain range of the associated reproduction number less than unity. Thus, for malaria, the classical requirement of having the associated reproduction number to be less than unity, although necessary, is not sufficient for its elimination. It is also shown, using centre manifold theory, that the full HIV-malaria co-infection model undergoes backward bifurcation. Simulations of the full HIV-malaria model show that the two diseases co-exist whenever their reproduction numbers exceed unity (with no competitive exclusion occurring). Further, the reduction in sexual activity of individuals with malaria symptoms decreases the number of new cases of HIV and the mixed HIV-malaria infection while increasing the number of malaria cases. Finally, these simulations show that the HIV-induced increase in susceptibility to malaria infection has marginal effect on the new cases of HIV and malaria but increases the number of new cases of the dual HIV-malaria infection.

Abstract Simultaneously hard and tough nitride ceramics open new venues for a variety of advanced applications. To produce such materials, attention is focused on the development of high-entropy ceramics, containing four or more metallic components distributed homogeneously in the metallic sublattice. While the fabrication of bulk high-entropy carbides and borides is well established, high-entropy nitrides have only been produced as thin films. Herein, we report on a newel three-step process to fabricate bulk high-entropy nitrides. The high-entropy nitride phase was obtained by exothermic combustion of mechanically-activated nanostructured metallic precursors in nitrogen and consolidated by spark plasma sintering. The fabricated bulk high-entropy nitride (Hf 0.2 Nb 0.2 Ta 0.2 Ti 0.2 Zr 0.2 )N demonstrates outstanding hardness (up to 33 GPa) and fracture toughness (up to 5.2 MPa∙m 1/2 ), significantly surpassing expected values from mixture rules, as well as all other reported binary and high-entropy ceramics and can be used for super-hard coatings, structural materials, optics, and others. The obtained results illustrate the scalable method to produce bulk high-entropy nitrides with the new benchmark properties.