137 research outputs found
Assessment of Groundwater Resources in Siwa Oasis, Western Desert, Egypt
One of the major challenges facing Egypt is limited water resources associated with rapid increase in population. In 1960s, Egyptian government started to use groundwater from the Nubian Sandstone Aquifer System (NSAS) in the Western Desert to expand agricultural sector. Siwa Oasis is the focus of this study to assess the efficiency of groundwater use and corresponding impacts from 1980 to 2012. Results show that from 1980 to 1998, withdrawal from poorly designed wells increased rapidly causing an increase in excess water about 336%. The increase of excess water with the usage of poor drainage produced lakes. Remote Sensing showed in 2000, there were 21,348 acres of lakes with an increase of 89% since 1987 due to unmanaged withdrawal. After management intervention, excess water decreased about 94.7% from 1998 to 2012 causing a decrease in lakes area by 24%. Groundwater electrical conductivity (EC) increased from 4.5 to 10.5 ds/m in 1996 and 2013, respectively. Yields of olives and date palms decreased about 46% and 55%, respectively from 2000 to 2011 resulting in net revenue decrease of more than 60%. Results show that salinity has a strong negative correlation with yield and net revenue. Findings showed the importance of developing a meaningful groundwater resources management plan for Siwa region
Clinical challenges in cutaneous leishmaniasis: A cohort from Southern Province, Sri Lanka
Southern Province of Sri Lanka is endemic to cutaneous leishmaniasis (CL). This study aims to describe the clinico-demographic profile of a cohort of CL patients (n=115, CL confirmed by PCR), reported at two main hospitals in the Matara and Hambantota districts of the Southern Province, highlighting the novel clinical presentations and possible challenges and/or favourable findings in the elimination of CL from the Province, along with a comparison with the provincial literature (Quality-checked publications of similar data) to identify possible disease trends, which could be useful in planning control programmes. We have found that CL is common in young males, and typically appears as single nodules in the upper limb. These nodules often contain high parasite loads. Our observations show that ulceration of papules and plaques is a new development in the province. This could have significant implications for differential diagnosis and chronicity. One positive trend we have observed is the early seeking of treatment, which had improved diagnostic rates. Additionally, there has been an increase in reporting of papules, which were silent reservoirs of CL. This indicates an increased awareness of the disease among patients in this cohort. However, several negative trends were identified as well. The Tangalle divisional secretariat division has emerged as a possible new disease focus. Furthermore, the high number of nodules and lesions with high parasite loads, which are likely to be less responsive to treatment, could pose challenges for CL elimination. It is important to note that these findings are based on a limited sample size and should be further investigated with a larger sample to gain more comprehensive understanding of the situation.
KEYWORDS: Cutaneous leishmaniasis, Southern Province, Sri Lanka, clinical, demographic, Leishmania donovani
 
Systematic Review of Medicine-Related Problems in Adult Patients with Atrial Fibrillation on Direct Oral Anticoagulants
New oral anticoagulant agents continue to emerge on the market and their safety requires assessment to provide evidence of their suitability for clinical use. There-fore, we searched standard databases to summarize the English language literature on medicine-related problems (MRPs) of direct oral anticoagulants DOACs (dabigtran, rivaroxban, apixban, and edoxban) in the treatment of adults with atri-al fibrillation. Electronic databases including Medline, Embase, International Pharmaceutical Abstract (IPA), Scopus, CINAHL, the Web of Science and Cochrane were searched from 2008 through 2016 for original articles. Studies pub-lished in English reporting MRPs of DOACs in adult patients with AF were in-cluded. Seventeen studies were identified using standardized protocols, and two reviewers serially abstracted data from each article. Most articles were inconclusive on major safety end points including major bleeding. Data on major safety end points were combined with efficacy. Most studies inconsistently reported adverse drug reactions and not adverse events or medication error, and no definitions were consistent across studies. Some harmful drug effects were not assessed in studies and may have been overlooked. Little evidence is provided on MRPs of DOACs in patients with AF and, therefore, further studies are needed to establish the safety of DOACs in real-life clinical practice
Influencing Factors on Student’s Willingness to Embrace Cloud Computing: An Empirical Study in Sri Lanka
Cloud computing is an important factor in the realm of information technology; however, its adoption by individual users and students remains insufficient. This paper examines the elements that affect students’ intention to use cloud services, addressing a gap in the literature that predominantly focuses on business customers. A structured questionnaire was given to 347 respondents in order to test a model based on the Theory of Planned Behavior (TPB) and the Technology Acceptance Model (TAM). Descriptive analysis, principal component analysis, and Structural Equation Modeling (SEM) were employed to infer the results. The findings indicate that perceived usefulness, perceived behavioral control, subjective norms, and attitudes toward cloud computing all exert a direct influence on students' intention to utilize cloud computing. It was found that behavioral intention was indirectly influenced by perceived ease of use, perceived transferability of computer skills, and trust in cloud computing providers. Additionally, perceived risk was directly affected by concerns related to vendor lock-in and security. Attitudes toward cloud computing were directly shaped by perceived usefulness, which, in turn, was indirectly influenced by ease of use, transferability of computer skills, and trust in providers. Furthermore, the results suggest that perceived usefulness acted as a fully mediating variable, whereas attitudes toward cloud computing served as only a partial mediator. As policy implications, the paper suggests that academic policies should enhance students' intention to adopt cloud services by emphasizing the practical benefits of cloud computing, enhancing user-friendliness, promoting digital literacy, ensuring data security and transparency, and fostering positive attitudes toward cloud technologies.
DOI: http://doi.org/10.31357/fhss/vjhss.v10i01.0
Discovery of ferromagnetism with large magnetic anisotropy in ZrMnP and HfMnP
ZrMnP and HfMnP single crystals are grown by a self-flux growth technique, and structural as well as temperature dependent magnetic and transport properties are studied. Both compounds have an orthorhombic crystal structure. ZrMnP and HfMnP are ferromagnetic with Curie temperatures around 370 K and 320 K, respectively. The spontaneous magnetizations of ZrMnP and HfMnP are determined to be 1.9 μB/f.u. and 2.1 μB/f.u., respectively, at 50 K. The magnetocaloric effect of ZrMnP in terms of entropy change (ΔS) is estimated to be −6.7 kJ m−3 K−1 around 369 K. The easy axis of magnetization is [100] for both compounds, with a small anisotropy relative to the [010] axis. At 50 K, the anisotropy field along the [001] axis is ∼4.6 T for ZrMnP and ∼10 T for HfMnP. Such large magnetic anisotropy is remarkable considering the absence of rare-earth elements in these compounds. The first principle calculation correctly predicts the magnetization and hard axis orientation for both compounds, and predicts the experimental HfMnP anisotropy field within 25%. More importantly, our calculations suggest that the large magnetic anisotropy comes primarily from the Mn atoms, suggesting that similarly large anisotropies may be found in other 3d transition metal compounds
Nodeless multiband superconductivity in stoichiometric single-crystalline CaKFe4As4
Measurements of the London penetration depth Δλ(T) and tunneling conductance in single crystals of the recently discovered stoichiometric iron-based superconductor CaKFe4As4 (CaK1144) show nodeless, two-effective-gap superconductivity with a larger gap of about 6-10 meV and a smaller gap of about 1-4 meV. Having a critical temperature Tc,onset≈35.8 K, this material behaves similar to slightly overdoped (Ba1-xKx)Fe2As2 (e.g., x=0.54,Tc≈34 K), a known multigap s± superconductor. We conclude that the superconducting behavior of stoichiometric CaK1144 demonstrates that two-gap s± superconductivity is an essential property of high-temperature superconductivity in iron-based superconductors, independent of the degree of substitutional disorderWe thank A. Gurevich, D. D. Johnson, A. Kaminski, V. G. Kogan, and Lin-Lin Wang for useful discussions. This work was supported by the US Department of Energy (DOE), Office of Science, Basic Energy Sciences, Materials Science and Engineering Division. Ames Laboratory is operated for the US DOE by Iowa State University under Contract DE-AC02-07CH11358. The work in Madrid was supported by the Spanish Ministry of Economy and Competitiveness (FIS2014-54498-R and MDM-2014-0377), by the Comunidad de Madrid through program Nanofrontmag-CM (S2013/MIT-2850) by Axa Research Fund, FP7-PEOPLE-2013-CIG 618321, and the European Research Council (Grant Agreement No. 679080). Madrid's group also acknowledges SEGAINVEX-UAM. W.R.M. was funded by the Gordon and Betty Moore Foundation's EPiQS Initiative through Grant GBMF441
Finding correspondence between metabolomic features in untargeted liquid chromatography-mass spectrometry metabolomics datasets.
Integration of multiple datasets can greatly enhance bioanalytical studies, for example, by increasing power to discover and validate biomarkers. In liquid chromatography-mass spectrometry (LC-MS) metabolomics, it is especially hard to combine untargeted datasets since the majority of metabolomic features are not annotated and thus cannot be matched by chemical identity. Typically, the information available for each feature is retention time (RT), mass-to-charge ratio (m/z), and feature intensity (FI). Pairs of features from the same metabolite in separate datasets can exhibit small but significant differences, making matching very challenging. Current methods to address this issue are too simple or rely on assumptions that cannot be met in all cases. We present a method to find feature correspondence between two similar LC-MS metabolomics experiments or batches using only the features' RT, m/z, and FI. We demonstrate the method on both real and synthetic datasets, using six orthogonal validation strategies to gauge the matching quality. In our main example, 4953 features were uniquely matched, of which 585 (96.8%) of 604 manually annotated features were correct. In a second example, 2324 features could be uniquely matched, with 79 (90.8%) out of 87 annotated features correctly matched. Most of the missed annotated matches are between features that behave very differently from modeled inter-dataset shifts of RT, MZ, and FI. In a third example with simulated data with 4755 features per dataset, 99.6% of the matches were correct. Finally, the results of matching three other dataset pairs using our method are compared with a published alternative method, metabCombiner, showing the advantages of our approach. The method can be applied using M2S (Match 2 Sets), a free, open-source MATLAB toolbox, available at https://github.com/rjdossan/M2S
Finding Correspondence between Metabolomic Features in Untargeted Liquid Chromatography-Mass Spectrometry Metabolomics Datasets
Integration of multiple datasets can greatly enhance bioanalytical studies, for example, by increasing power to discover and validate biomarkers. In liquid chromatography-mass spectrometry (LC-MS) metabolomics, it is especially hard to combine untargeted datasets since the majority of metabolomic features are not annotated and thus cannot be matched by chemical identity. Typically, the information available for each feature is retention time (RT), mass-to-charge ratio (m/z), and feature intensity (FI). Pairs of features from the same metabolite in separate datasets can exhibit small but significant differences, making matching very challenging. Current methods to address this issue are too simple or rely on assumptions that cannot be met in all cases. We present a method to find feature correspondence between two similar LC-MS metabolomics experiments or batches using only the features' RT, m/z, and FI. We demonstrate the method on both real and synthetic datasets, using six orthogonal validation strategies to gauge the matching quality. In our main example, 4953 features were uniquely matched, of which 585 (96.8%) of 604 manually annotated features were correct. In a second example, 2324 features could be uniquely matched, with 79 (90.8%) out of 87 annotated features correctly matched. Most of the missed annotated matches are between features that behave very differently from modeled inter-dataset shifts of RT, MZ, and FI. In a third example with simulated data with 4755 features per dataset, 99.6% of the matches were correct. Finally, the results of matching three other dataset pairs using our method are compared with a published alternative method, metabCombiner, showing the advantages of our approach. The method can be applied using M2S (Match 2 Sets), a free, open-source MATLAB toolbox, available at https://github.com/rjdossan/M2S
Effect of dry or wet substrate deposition on the organic volume fraction of core–shell aerosol particles
Understanding the impact of sea spray aerosol (SSA) on the
climate and atmosphere requires quantitative knowledge of their chemical
composition and mixing states. Furthermore, single-particle measurements are
needed to accurately represent large particle-to-particle variability. To
quantify the mixing state, the organic volume fraction (OVF), defined as the
relative organic volume with respect to the total particle volume, is
measured after generating and collecting aerosol particles, often using
deposition impactors. In this process, the aerosol streams are either dried
or kept wet prior to impacting on solid substrates. However, the atmospheric
community has yet to establish how dry versus wet aerosol deposition
influences the impacted particle morphologies and mixing states. Here, we
apply complementary offline single-particle atomic force microscopy (AFM)
and bulk ensemble high-performance liquid chromatography (HPLC) techniques
to assess the effects of dry and wet deposition modes on the
substrate-deposited aerosol particles' mixing states. Glucose and NaCl
binary mixtures that form core–shell particle morphologies were studied as
model systems, and the mixing states were quantified by measuring the OVF of
individual particles using AFM and compared to the ensemble measured by
HPLC. Dry-deposited single-particle OVF data positively deviated from the
bulk HPLC data by up to 60 %, which was attributed to significant
spreading of the NaCl core upon impaction with the solid substrate. This led
to underestimation of the core volume. This problem was circumvented by (a) performing wet deposition and thus bypassing the effects of the solid core
spreading upon impaction and (b) performing a hydration–dehydration cycle on
dry-deposited particles to restructure the deformed NaCl core. Both
approaches produced single-particle OVF values that converge well with the
bulk and expected OVF values, validating the methodology. These findings
illustrate the importance of awareness in how conventional particle
deposition methods may significantly alter the impacted particle
morphologies and their mixing states.</p
Metabolic Deficiences Revealed in the Biotechnologically Important Model Bacterium Escherichia coli BL21(DE3)
The Escherichia coli B strain BL21(DE3) has had a profound impact on biotechnology through its use in the production of recombinant proteins. Little is understood, however, regarding the physiology of this important E. coli strain. We show here that BL21(DE3) totally lacks activity of the four [NiFe]-hydrogenases, the three molybdenum- and selenium-containing formate dehydrogenases and molybdenum-dependent nitrate reductase. Nevertheless, all of the structural genes necessary for the synthesis of the respective anaerobic metalloenzymes are present in the genome. However, the genes encoding the high-affinity molybdate transport system and the molybdenum-responsive transcriptional regulator ModE are absent from the genome. Moreover, BL21(DE3) has a nonsense mutation in the gene encoding the global oxygen-responsive transcriptional regulator FNR. The activities of the two hydrogen-oxidizing hydrogenases, therefore, could be restored to BL21(DE3) by supplementing the growth medium with high concentrations of Ni2+ (Ni2+-transport is FNR-dependent) or by introducing a wild-type copy of the fnr gene. Only combined addition of plasmid-encoded fnr and high concentrations of MoO42− ions could restore hydrogen production to BL21(DE3); however, to only 25–30% of a K-12 wildtype. We could show that limited hydrogen production from the enzyme complex responsible for formate-dependent hydrogen evolution was due solely to reduced activity of the formate dehydrogenase (FDH-H), not the hydrogenase component. The activity of the FNR-dependent formate dehydrogenase, FDH-N, could not be restored, even when the fnr gene and MoO42− were supplied; however, nitrate reductase activity could be recovered by combined addition of MoO42− and the fnr gene. This suggested that a further component specific for biosynthesis or activity of formate dehydrogenases H and N was missing. Re-introduction of the gene encoding ModE could only partially restore the activities of both enzymes. Taken together these results demonstrate that BL21(DE3) has major defects in anaerobic metabolism, metal ion transport and metalloprotein biosynthesis
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