320 research outputs found

    The Effectiveness of Entrepreneurship Programs to Reduce Unemployment in Developing Countries: The Case of Saudi Arabia

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    Starting a new business, developing new products and/or services and bringing those to the market may seem deceitfully easy, but in reality, it is a very painful and risky endeavor that can be nearly impossible to undertake without proper implementation process in place. Several entrepreneurship programs have been established in different regions or countries to make a positive economic change while remaining profitable for both people and the government. Saudi Arabia is a rich country that enjoys high financial potential. In spite of the country is taking remarkable steps into the entrepreneurship world, there are still unique challenges that inspire or hamper entrepreneurs to engage in the entrepreneur programs\u27 process more fully. In this paper, we explored these challenges and show the transformation of the ecosystem strategy that the Saudi Arabia government has taken to develop the entrepreneurship ecosystem and startup. The study aims to investigate and analyze the relationships between the effectiveness of entrepreneurship programs and unemployment. The paper, however, concludes that the existing entrepreneurship ecosystem is still needed development in order to resolve the problem of unemployment in Saudi Arabia. The country should improve the strategies that can support to create an entrepreneurial culture and encourage the youth to involve in starting new enterprises

    Towards derived equivalence classification of the cluster-tilted algebras of Dynkin type D

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    We provide a far reaching derived equivalence classification of the cluster-tilted algebras of Dynkin type D and suggest standard forms for the derived equivalence classes. We believe that the classification is complete, but some subtle questions remain open. We introduce another notion of equivalence called good mutation equivalence which is slightly stronger than derived equivalence but is algorithmically more tractable, and give a complete classification together with standard forms.Comment: 42 pages; v2: Minor revision. Title and abstract changed, slight changes to the introduction and in the presentation of main results in Section

    Fluorescent substrates for haloalkane dehalogenases: Novel probes for mechanistic studies and protein labeling

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    Haloalkane dehalogenases are enzymes that catalyze the cleavage of carbon-halogen bonds in halogenated compounds. They serve as model enzymes for studying structure-function relationships of >100.000 members of the alpha/beta-hydrolase superfamily. Detailed kinetic analysis of their reaction is crucial for understanding the reaction mechanism and developing novel concepts in protein engineering. Fluorescent substrates, which change their fluorescence properties during a catalytic cycle, may serve as attractive molecular probes for studying the mechanism of enzyme catalysis. In this work, we present the development of the first fluorescent substrates for this enzyme family based on coumarin and BODIPY chromophores. Steady-state and pre-steady-state kinetics with two of the most active haloalkane dehalogenases, DmmA and LinB, revealed that both fluorescent substrates provided specificity constant two orders of magnitude higher (0.14-12.6 mu M(-1)s(-1)) than previously reported representative substrates for the haloalkane dehalogenase family (0.00005-0.014 mu M(-1)s(-1)). Stopped-flow fluorescence/FRET analysis enabled for the first time monitoring of all individual reaction steps within a single experiment: (i) substrate binding, (ii-iii) two subsequent chemical steps and (iv) product release. The newly introduced fluorescent molecules are potent probes for fast steady-state kinetic profiling. In combination with rapid mixing techniques, they provide highly valuable information about individual kinetic steps and mechanism of haloalkane dehalogenases. Additionally, these molecules offer high specificity and efficiency for protein labeling and can serve as probes for studying protein hydration and dynamics as well as potential markers for cell imaging. (C) 2020 The Authors. Published by Elsevier B.V. on behalf of Research Network of Computational and Structural Biotechnology

    Guiding structures with multiply connected cross-sections: evolution of propagation in external fields at complex Robin parameters

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    Properties of the two-dimensional ring and three-dimensional infinitely long straight hollow waveguide with unit width and inner radius ρ0\rho_0 in the superposition of the longitudinal uniform magnetic field B\bf B and Aharonov-Bohm flux are analyzed within the framework of the scalar Helmholtz equation under the assumption that the Robin boundary conditions at the inner and outer confining walls contain extrapolation lengths Λin\Lambda_{in} and Λout\Lambda_{out}, respectively, with nonzero imaginary parts. It is shown that, compared to the disk geometry, the annulus opens up additional possibilities of varying magnetization and currents by tuning imaginary components of the Robin parameters on each confining circumference; in particular, the possibility of restoring a lossless longitudinal flux by zeroing imaginary part EiE_i of the total transverse energy EE is discussed. The energy EE turns real under special correlation between the imaginary parts of Λin\Lambda_{in} and Λout\Lambda_{out} with the opposite signs what physically corresponds to the equal transverse fluxes through the inner and outer interfaces of the annulus. In the asymptotic case of the very large radius, simple expressions are derived and applied to the analysis of the dependence of the real energy EE on Λin\Lambda_{in} and Λout\Lambda_{out}. New features also emerge in the magnetic field influence; for example, if, for the quantum disk, the imaginary energy EiE_i is quenched by the strong intensities BB, then for the annulus this takes place only when the inner Robin distance Λin\Lambda_{in} is real; otherwise, it almost quadratically depends on BB with the corresponding enhancement of the reactive scattering. Closely related problem of the hole in the otherwise uniform medium is also addressed for real and complex extrapolation lengths with the emphasis on the comparative analysis with its dot counterpart.Comment: 37 pages, 9 figure

    Classifying atopic dermatitis: a systematic review of phenotypes and associated characteristics.

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    Atopic dermatitis is a heterogeneous disease, accompanied by a wide variation in disease presentation and the potential to identify many phenotypes that may be relevant for prognosis and treatment. We aimed to systematically review previously reported phenotypes of atopic dermatitis and any characteristics associated with them. Ovid EMBASE, Ovid MEDLINE and Web of Science were searched from inception till 12 February 2021 for studies attempting to classify atopic dermatitis. Primary outcomes are atopic dermatitis phenotypes and characteristics associated with them in subsequent analyses. A secondary outcome is the methodological approach used to derive them. In total, 8511 records were found. By focussing only on certain clinical phenotypes, 186 studies were eligible for inclusion. The majority of studies were hospital-based (59%, 109/186) and cross-sectional (76%, 141/186). The number of included patients ranged from seven to 526 808. Data-driven approaches to identify phenotypes were only used in a minority of studies (7%, 13/186). Ninety-one studies (49%) investigated a phenotype based on disease severity. A phenotype based on disease trajectory, morphology and eczema herpeticum was investigated in 56 (30%), 22 (12%) and 11 (6%) studies respectively. Thirty-six studies (19%) investigated morphological characteristics in other phenotypes. Investigated associated characteristics differed between studies. In conclusion, we present an overview of phenotype definitions used in literature for severity, trajectory, morphology and eczema herpeticum, including associated characteristics. There is a lack of uniform and consistent use of atopic dermatitis phenotypes across studies

    The influence of low-grade glioma on resting state oscillatory brain activity: a magnetoencephalography study

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    Purpose In the present MEG-study, power spectral analysis of oscillatory brain activity was used to compare resting state brain activity in both low-grade glioma (LGG) patients and healthy controls. We hypothesized that LGG patients show local as well as diffuse slowing of resting state brain activity compared to healthy controls and that particularly global slowing correlates with neurocognitive dysfunction. Patient and methods Resting state MEG recordings were obtained from 17 LGG patients and 17 age-, sex-, and education-matched healthy controls. Relative spectral power was calculated in the delta, theta, upper and lower alpha, beta, and gamma frequency band. A battery of standardized neurocognitive tests measuring 6 neurocognitive domains was administered. Results LGG patients showed a slowing of the resting state brain activity when compared to healthy controls. Decrease in relative power was mainly found in the gamma frequency band in the bilateral frontocentral MEG regions, whereas an increase in relative power was found in the theta frequency band in the left parietal region. An increase of the relative power in the theta and lower alpha band correlated with impaired executive functioning, information processing, and working memory. Conclusion LGG patients are characterized by global slowing of their resting state brain activity and this slowing phenomenon correlates with the observed neurocognitive deficits

    Imaging the nanoscale organization of peptidoglycan in living Lactococcus lactis cells

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    Peptidoglycans provide bacterial cell walls with mechanical strength. The spatial organization of peptidoglycan has previously been difficult to study. Here, atomic force microscopy, together with cells carrying mutations in cell-wall polysaccharides, has allowed an in-depth study of these molecules

    A Genome-Wide Association Study of Total Bilirubin and Cholelithiasis Risk in Sickle Cell Anemia

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    Serum bilirubin levels have been associated with polymorphisms in the UGT1A1 promoter in normal populations and in patients with hemolytic anemias, including sickle cell anemia. When hemolysis occurs circulating heme increases, leading to elevated bilirubin levels and an increased incidence of cholelithiasis. We performed the first genome-wide association study (GWAS) of bilirubin levels and cholelithiasis risk in a discovery cohort of 1,117 sickle cell anemia patients. We found 15 single nucleotide polymorphisms (SNPs) associated with total bilirubin levels at the genome-wide significance level (p value <5×10−8). SNPs in UGT1A1, UGT1A3, UGT1A6, UGT1A8 and UGT1A10, different isoforms within the UGT1A locus, were identified (most significant rs887829, p = 9.08×10−25). All of these associations were validated in 4 independent sets of sickle cell anemia patients. We tested the association of the 15 SNPs with cholelithiasis in the discovery cohort and found a significant association (most significant p value 1.15×10−4). These results confirm that the UGT1A region is the major regulator of bilirubin metabolism in African Americans with sickle cell anemia, similar to what is observed in other ethnicities
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