1,462 research outputs found

    Modeling power grids

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    We present a method to construct random model power grids that closely match statistical properties of a real power grid. The model grids are more difficult to partition than a real grid.Comment: 9 pages, 5 figure

    Cl electrosorption on Ag(100): Lateral interactions and electrosorption valency from comparison of Monte Carlo simulations with chronocoulometry experiments

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    We present Monte Carlo Simulations using an equilibrium lattice-gas model for the electrosorption of Cl on Ag(100) single-crystal surfaces. Fitting the simulated isotherms to chronocoulometry experiments, we extract parameters such as the electrosorption valency gamma and the next-nearest-neighbor lateral interaction energy phi_nnn. Both coverage-dependent and coverage independent gamma were previously studied assuming a constant phi_nnn [I. Abou Hamad, Th. Wandlowski, G. Brown, P.A. Rikvold, J. Electroanal. Chem. 554-555 (2003) 211]. Here, a self-consistent, entirely electrostatic picture of the lateral interactions with a coverage-dependent phi_nnn is developed, and a relationship between phi_nnn and gamma is investigated for Cl on Ag(100).Comment: Accepted for publication in Electrochimica Acta, 10 pages, 7 figures, 2 tables and an appendi

    Effects of lateral diffusion on morphology and dynamics of a microscopic lattice-gas model of pulsed electrodeposition

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    The influence of nearest-neighbor diffusion on the decay of a metastable low-coverage phase (monolayer adsorption) in a square lattice-gas model of electrochemical metal deposition is investigated by kinetic Monte Carlo simulations. The phase-transformation dynamics are compared to the well-established Kolmogorov-Johnson-Mehl-Avrami theory. The phase transformation is accelerated by diffusion, but remains in accord with the theory for continuous nucleation up to moderate diffusion rates. At very high diffusion rates the phase-transformation kinetic shows a crossover to instantaneous nucleation. Then, the probability of medium-sized clusters is reduced in favor of large clusters. Upon reversal of the supersaturation, the adsorbate desorbs, but large clusters still tend to grow during the initial stages of desorption. Calculation of the free energy of subcritical clusters by enumeration of lattice animals yields a quasi-equilibrium distribution which is in reasonable agreement with the simulation results. This is an improvement relative to classical droplet theory, which fails to describe the distributions, since the macroscopic surface tension is a bad approximation for small clusters.Comment: Minor corrections and modifications. 15 pages with 10 figures. Accepted for publication in the Journal of Chemical Physics, see http://jcp.aip.org/jcp

    ASSESSMENT OF THE ENVIRONMENTAL SENSITIVITY OF DESERTIFICATION IN SOUTHERN IRAQ, AL-SAMAWA BADIA USING GIS AND RS TECHNIQUES

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    This study was aimed to investigate and evaluates the degree of environmental sensitivity of desertification and to provide solutions, treatments by identifying the elements and indicators that are directly linked to desertification in southern Iraq.  GIS technique was used, and mapping of environmentally sensitive areas for desertification. Five important indices including (soil quality index SQI, climate quality index CQI, vegetation quality index VQI, management quality index MQI, and groundwater quality index GWQI) were used. Results showed that the SQI index was varied between high, moderate, and low quality, the VQI index was varied between moderate to low quality, as for the indices of (CQI, MQI, and GWQI), all classifications were within the lower class. This was reflected negatively on the values of environmental sensitivity to desertification (ESAI) and it became in the critical category within the study area. Consequently, the environmental sensitivity to desertification was calculated by excluding the indices of MQI, and GWQI. Four classes were detected (None affected, Potential, Fragile, and Critical) divided into sub-classes (N, P, F3, C1, C3)

    Effectiveness of a community-led shared book reading intervention in Syrian refugee children: a randomised controlled trial.

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    Community-led, shared book reading programs may help improve refugee children's reading abilities and attitudes towards reading. We Love Reading (WLR)-a light-touch, community-led, shared book reading program-was evaluated in a pre-registered, wait-listed, randomised controlled trial (AEARCTR-0006523). 322 Syrian refugee mother-child dyads (children: 4-8-year-olds, 50.0% female) in Jordan were tested at two timepoints, 15 weeks apart. WLR did not significantly affect child literacy or child-reported child attitudes toward reading (ps > 0.05). Mothers did report improved child attitudes toward reading from WLR (p = 0.046, η2 = 0.013). The intervention did not lead to improvements in family relationships (ps > 0.05). WLR may have promise in improving attitudes toward reading in forcibly displaced children but did not affect literacy or child-reported attitudes toward reading; these results provide insight into what changes are needed for effective shared book reading interventions in this population

    Acetyl-L-carnitine and/or liposomal co-enzyme Q10 prevent propionic acid-induced neurotoxicity by modulating oxidative tissue injury, inflammation, and ALDH1A1-RA-RARα signaling in rats

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    Propionic acid (PPA) is a short-chain fatty acid produced endogenously by gut microbiota and found in foodstuffs and pharmaceutical products as an additive. Exposure to PPA has been associated with the development of autism spectrum disorder (ASD). The purpose of this study was to investigate the protective effect of acetyl‐L‐carnitine (ALCAR) and liposomal Co-enzyme Q10 (CoQ10) against cerebral and cerebellar oxidative injury, inflammation, and cell death, and alterations in ALDH1A1-RA-RARα signaling in an autism-like rat model induced by PPA. The rats were treated with PPA and concurrently received ALCAR and/or CoQ10 for 5 days. The animals were sacrificed, and the cerebral cortex and cerebellum were collected for analysis. PPA caused histopathological alterations along with increased malondialdehyde (MDA), NF-ÎșB p65, TNF-α, and IL-6 in the cerebrum and cerebellum of rats. Reduced glutathione (GSH) and antioxidant enzymes were declined in the brain of rats that received PPA. Concurrent treatment with ALCAR and/or CoQ10 prevented tissue injury, decreased MDA, NF-ÎșB p65, and pro-inflammatory cytokines, and enhanced cellular antioxidants in PPA-administered rats. ALCAR and/or CoQ10 upregulated Bcl-2 and decreased Bax and caspase-3 in the brain of rats. In addition, ALCAR and/or CoQ10 upregulated cerebral and cerebellar ALDH1A1 and RARα in PPA-treated rats. The combination of ALCAR and CoQ10 showed more potent effects when compared with the individual treatments. In conclusion, ALCAR and/or CoQ10 prevented tissue injury, ameliorated oxidative stress, inflammatory response, and apoptosis, and upregulated ALDH1A1-RA-RARα signaling in the brain of autistic rats

    The association between molar incisor hypomineralization and oral health-related quality of life: a cross-sectional study

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    Objectives: We aimed to assess the association between molar incisor hypomineralization (MIH) and the oral health-related quality of life (OHRQoL) in a group of 7- to 14-year-old children in Berlin, Germany. Materials and methods: The cross-sectional study consisted of a consecutive sample of 317 children, aged 7-14 years (49% girls, 51% boys; mean age, 8.71). Data were collected between June 2018 and December 2019. MIH was diagnosed using the criteria of the European Academy of Paediatric Dentistry. OHRQoL was assessed using the German 19-item version of the Child Oral Health Impact Profile (COHIP-G19). Differences in COHIP-19 summary scores between controls without MIH and MIH patients and with regards to MIH severity were tested for statistical significance using t test and analysis of variance (ANOVA), respectively. Results: Data were obtained for 217 untreated MIH patients and 100 controls. OHRQoL of MIH patients was significantly more impaired than of controls indicated by COHIP-19 mean scores (60.9 +/- 10.7 vs. 67.9 +/- 7.8; p < 0.001). Patients with severe MIH (59.6 +/- 11.0) reported significantly worse OHRQoL than patients with mild MIH (63.6 +/- 9.1; p = 0.013). Conclusions: MIH has a significant negative impact on the children's OHRQoL. Patients with severe MIH experience a greater negative impact on OHRQoL than those diagnosed with mild MIH. Clinical significance: MIH is one of the major dental problems of our time; pediatric dentists should be aware of its impact on the OHRQoL of the patient

    1/T_1 nuclear relaxation time of \kappa-(BEDT-TTF)_ 2 Cu [N(CN)_2] Cl : effects of magnetic frustration

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    We study the role played by the magnetic frustration in the antiferromagnetic phase of the organic salt \kappa-(BEDT-TTF)_ 2 Cu [N(CN)_2] Cl. Using the spatially anisotropic triangular Heisenberg model we analyze previous and new performed NMR experiments. We compute the 1/T_1 relaxation time by means of the modified spin wave theory. The strong suppression of the nuclear relaxation time observed experimentally under varying pressure and magnetic field is qualitatively well reproduced by the model. Our results suggest the existence of a close relation between the effects of pressure and magnetic frustration.Comment: 10 pages, 9 figures, to appear in Journal of Phys.: Condens Matte

    Predictors of Literacy and Attitudes Toward Reading Among Syrian Refugee Children in Jordan

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    Refugee children often face disruptions to their education before and during displacement. However, little is known about either levels or predictors of refugee children’s literacy or about their attitudes toward reading in low- or middle-income countries. To address this, we conducted in-home literacy assessments using the Holistic Assessment of Learning and Development Outcomes with 322 Syrian refugee mother–child dyads who lived in Jordan (child age range 4–8 years, M = 6.32 years, 50% female). Overall, the children had quite low levels of literacy, although they indicated a strong enthusiasm for reading. Child age, maternal education, and maternal ability to read all predicted child literacy, although maternal literacy predicted it only among children enrolled in school. Among those enrolled in school (64.9% of the total sample, 88.7% of those aged ≄ 6), students attending hybrid classes had better literacy than those attending either solely in-person or solely online, although the frequency of school attendance did not predict literacy. A less consistent pattern emerged for predicting children’s attitudes toward reading. Our results suggest an urgent need to improve literacy skills among refugee children in Jordan, as well as a need for validated measures of attitudes toward reading for use with Arabic-speaking youth. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s13158-022-00334-x
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