On the Uniqueness of Solution of Magnetostatic Vector‐potential Problems by Three‐dimensional Finite‐element Methods

In this paper, particular attention is paid to the impact of finite‐element approximation on uniqueness and to approximations implicit in finite element formulations from the uniqueness requirements standpoint. It is also shown that the flux density is unique without qualifications. The theoretical and numerical uniqueness of the magnetic vector potential in three‐dimensional problems is also given. This analysis is restricted to linear, isotropic media with Dirichlet Boundary conditions. As an interesting consequence of this analysis it is shown that, under usual conditions adopted in obtaining three‐dimensional finite‐element solutions, it is not necessary to specify div Ā in order that Ā be uniquely defined

A Review of Models for Evaluation of Climate Change Impact on Water Resources

The use of models to simulate or predict impact of climate change on water resources management is very vital due to continual increase in global warming which invariably affects most important natural resources in the environment. This paper provides an overview of the existing models used for evaluating climate change impact on water resources management. It also compares their relative advantages and drawbacks. It was found that no model can perform satisfactorily the assessment of climate change impact; hence it may be necessary to use one model to compliment the weakness of another. Global Circulation Model (GCM) is not easily accessible in developing countries due to sophistications and processes involved in running it. Moreso, the nature of available data and cost of acquiring it is high. The main advantage of Water Balance (WATBAL) model is that it can model climate change impact in water resources but its major drawback is that it requires many inputs of hydro-meteorological parameters. Regression and Artificial Neural Network (ANN) models are readily available and not too expensive. They can model climate change impact on water resources and hydropower operation. However, the drawback is that enormous data are required for ANN model calibration and operation. It is imperative therefore to anticipate and efficiently prepare for future water resources management and suggest necessary measures to mitigate the effect of climate change

Connection between the "Strutinsky level density" and the semiclassical level density (published version)

We establish an analytical link between the level density obtained by means of the Strutinsky averaging method, and the semiclassical level density. This link occurs only in the so-called "asymptotic limit". It turns out that the Strutinsky method amounts to an approximation to the semiclassical method. This approximation contains an unavoidable remainder which constitutes an intrinsic noise in comparison to the semiclassical method. Thus, the "old" problem of the dependency of the Strutinsky procedure on the two free smoothing parameters of the averaging is intimately connected to this noise. On the other hand, we demonstrate that the noise of the method is small in the average density of states and in the average energy, whereas it might be non-negligible in the shell correction itself. In order to improve this method, we give a "rule" which consists simply of minimizing the relative error made on the average energy.Comment: 6 figure

Factors associated with emergency department green zone utilization in hospital

Introduction: In hospital, emergency departments are highly utilized by patients. Overcrowding, congestion and long waiting time were among the issues highlighted resulting from it. In Selangor, there has been a steady increase in utilization of emergency department of government hospitals over the past five (5) years. Utilization of green zone was the highest in these hospitals. Being a department that provides a comprehensive emergency service and provides easy access for the community, issues of appropriateness utilization arise. This study aims to determine the level of appropriateness of green zone utilization by patients attending Emergency Department in Serdang Hospital and factors influencing its utilization. Methodology: A cross-sectional study was conducted in Emergency Department of Serdang Hospital. Sample sizes of green zone adult patients were obtained by systematic random sampling. Emergency Medicine and Trauma Services Policy Malaysia 2012 were used to classify patients to appropriate and inappropriate utilization of green zone. Pre-tested self-administered questionnaire were used to interview patients. Descriptive statistics, chi-square test and logistic regression used to analyse the data collected. Data analysis conducted using IBM SPSS Statistics version 22 and p value significant at <0.05. Result: There were 793 (90.7%) patients in this study. It was found that level of appropriateness utilization in green zone emergency department was 83.6% appropriate and 16.4% was inappropriate. Median age of patients were 29 years old (IQR ± 25th, 75th; 23, 40). Majority were Malays (74%). The results of chi-square test indicated that there were significant association between marital status (p=0.032), patients attending emergency department because treatment cost is cheap (p=0.025), emergency department operates 24 hours (p=0.045) and time of patient presentation to emergency department (p=0.001). From the study, the multivariate results revealed that the odds of married patients (AOR=1.481, 95% CI: 1.008, 2.174) to utilize the emergency department were higher than not married patients, the odds of patients utilize emergency department not because of the cheap treatment (AOR=1.614, 95% CI: 1.073, 2.469) was almost two times more and lastly the odds of utilization after office hours were two times more than during office hours (AOR=2.117, 95% CI: 1.388, 3.227). Conclusion: The study revealed majority of patients utilized green zone appropriately. Married patient, patient attend emergency department not because treatment cost is cheap and patient attending after office hour were significantly associated with appropriateness utilization of emergency department. Further study needed to determine the cause and effect relationship

Charged Nanoparticles Quench the Propulsion of Active Janus Colloids

Active colloidal particles regularly interact with surfaces in applications ranging from microfluidics to sensing. Recent work has revealed the complex nature of these surface interactions for active particles. Herein, we summarize experiments and simulations that show the impact of charged nanoparticles on the propulsion of an active colloid near a boundary. Adding charged nanoparticles not only decreased the average separation distance of a passive colloid because of depletion attraction as expected but also decreased the apparent propulsion of a Janus colloid to near zero. Complementary agentbased simulations considering the impact of hydrodynamics for active Janus colloids were conducted in the range of separation distances inferred from experiment. These simulations showed that propulsion speed decreased monotonically with decreasing average separation distance. Although the trend found in experiments and simulations was in qualitative agreement, there was still a significant difference in the magnitude of speed reduction. The quantitative difference was attributed to the influence of charged nanoparticles on the conductivity of the active particle suspension. Follow-up experiments delineating the impact of depletion and conductivity showed that both contribute to the reduction of speed for an active Janus particle. The experimental and simulated data suggests that it is necessary to consider the synergistic effects between various mechanisms influencing interactions experienced by an active particle near a boundary

Medicinal Plants Traditionally Used in the Management of COVID-19 in Kurdistan Region of Iraq

Coronaviruses are infectious respiratory tract illnesses, but they can also affect the digestive tract and infect both humans and animals. The new coronavirus results in complicated health problems all over the world. The most urgent concern of all researchers around the world has been the treatment of the virus. The following study aimed to use quantitative ethnobotany to help scientist in addressing the deadly virus. Expert sampling method was adopted with the aid of an in-depth interview guide. Thirty-nine respondents were interviewed. Eighty-one medicinal plant species from 35 families were documented. Males 25 (64.1%) constitute the greater percentage of the total respondents. Majority of the respondents had formal education. Eighty-one medicinal plant species from 35 families were documented. Leaves are the most utilized 25.8 followed by seed 17.7 and fruits 12.1%, respectively. Relative frequency of citation ranged from 0.5 to 0.9, whereas the FL value ranged from 0.4 to 0.85, revealing how effective the documented plant species are in the management of COVID-19 in the region. A greater amount of research into documented medicinal plants is warranted because of the high likelihood that they contain many active ingredients

Low-lying quadrupole collective states of the light and medium Xenon isotopes

Collective low lying levels of light and medium Xenon isotopes are deduced from the Generalized Bohr Hamiltonian (GBH). The microscopic seven functions entering into the GBH are built from a deformed mean field of the Woods-Saxon type. Theoretical spectra are found to be close to the ones of the experimental data taking into account that the calculations are completely microscopic, that is to say, without any fitting of parameters.Comment: 8 pages, 4 figures, 1 tabl

Charged Nanoparticles Quench the Propulsion of Active Janus Colloids

Active colloidal particles regularly interact with surfaces in applications ranging from microfluidics to sensing. Recent work has revealed the complex nature of these surface interactions for active particles. Herein, we summarize experiments and simulations that show the impact of charged nanoparticles on the propulsion of an active colloid near a boundary. Adding charged nanoparticles not only decreased the average separation distance of a passive colloid because of depletion attraction as expected but also decreased the apparent propulsion of a Janus colloid to near zero. Complementary agentbased simulations considering the impact of hydrodynamics for active Janus colloids were conducted in the range of separation distances inferred from experiment. These simulations showed that propulsion speed decreased monotonically with decreasing average separation distance. Although the trend found in experiments and simulations was in qualitative agreement, there was still a significant difference in the magnitude of speed reduction. The quantitative difference was attributed to the influence of charged nanoparticles on the conductivity of the active particle suspension. Follow-up experiments delineating the impact of depletion and conductivity showed that both contribute to the reduction of speed for an active Janus particle. The experimental and simulated data suggests that it is necessary to consider the synergistic effects between various mechanisms influencing interactions experienced by an active particle near a boundary

Beam profile investigation of the new collimator system for the J-PET detector

Jagiellonian Positron Emission Tomograph (J-PET) is a multi-purpose detector which will be used for search for discrete symmetries violations in the decays of positronium atoms and for investigations with positronium atoms in life-sciences and medical diagnostics. In this article we present three methods for determination of the beam profile of collimated annihilation gamma quanta. Precise monitoring of this profile is essential for time and energy calibration of the J-PET detector and for the determination of the library of model signals used in the hit-time and hit-position reconstruction. We have we have shown that usage of two lead bricks with dimensions of 5x10x20 cm^3 enables to form a beam of annihilation quanta with Gaussian profile characterized by 1 mm FWHM. Determination of this characteristic is essential for designing and construction the collimator system for the 24-module J-PET prototype. Simulations of the beam profile for different collimator dimensions were performed. This allowed us to choose optimal collimation system in terms of the beam profile parameters, dimensions and weight of the collimator taking into account the design of the 24 module J-PET detector.Comment: 14 pages, 9 figure

Extended magic phase in twisted graphene multilayers

Theoretical and experimental studies have verified the existence of ``magic angles'' in twisted bilayer graphene, where the twist between layers gives rise to flat bands and consequently highly correlated phases. Narrow bands can also exist in multilayers with alternating twist angles, and recent theoretical work suggests that they can also be found in trilayers with twist angles between neighboring layers in the same direction. We show here that flat bands exist in a variety of multilayers where the ratio between twist angles is close to coprime integers. We generalize previous analyses, and, using the chiral limit for interlayer coupling, give examples of many combinations of twist angles in stacks made up of three and four layers which lead to flat bands. The technique we use can be extended to systems with many layers. Our results suggest that flat bands can exist in graphene multilayers with angle disorder, that is, narrow samples of turbostatic graphite.Comment: Main text: 4 pages, 4 figures -- Supplementary Material: 15 pages, 13 figure