462 research outputs found

    Sub-electron Charge Relaxation via 2D Hopping Conductors

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    We have extended Monte Carlo simulations of hopping transport in completely disordered 2D conductors to the process of external charge relaxation. In this situation, a conductor of area L×WL \times W shunts an external capacitor CC with initial charge QiQ_i. At low temperatures, the charge relaxation process stops at some "residual" charge value corresponding to the effective threshold of the Coulomb blockade of hopping. We have calculated the r.m.s.. value QRQ_R of the residual charge for a statistical ensemble of capacitor-shunting conductors with random distribution of localized sites in space and energy and random QiQ_i, as a function of macroscopic parameters of the system. Rather unexpectedly, QRQ_{R} has turned out to depend only on some parameter combination: X0LWν0e2/CX_0 \equiv L W \nu_0 e^2/C for negligible Coulomb interaction and XχLWκ2/C2X_{\chi} \equiv LW \kappa^2/C^{2} for substantial interaction. (Here ν0\nu_0 is the seed density of localized states, while κ\kappa is the dielectric constant.) For sufficiently large conductors, both functions QR/e=F(X)Q_{R}/e =F(X) follow the power law F(X)=DXβF(X)=DX^{-\beta}, but with different exponents: β=0.41±0.01\beta = 0.41 \pm 0.01 for negligible and β=0.28±0.01\beta = 0.28 \pm 0.01 for significant Coulomb interaction. We have been able to derive this law analytically for the former (most practical) case, and also explain the scaling (but not the exact value of the exponent) for the latter case. In conclusion, we discuss possible applications of the sub-electron charge transfer for "grounding" random background charge in single-electron devices.Comment: 12 pages, 5 figures. In addition to fixing minor typos and updating references, the discussion has been changed and expande

    A Numerical Study of Coulomb Interaction Effects on 2D Hopping Transport

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    We have extended our supercomputer-enabled Monte Carlo simulations of hopping transport in completely disordered 2D conductors to the case of substantial electron-electron Coulomb interaction. Such interaction may not only suppress the average value of hopping current, but also affect its fluctuations rather substantially. In particular, the spectral density SI(f)S_I (f) of current fluctuations exhibits, at sufficiently low frequencies, a 1/f1/f-like increase which approximately follows the Hooge scaling, even at vanishing temperature. At higher ff, there is a crossover to a broad range of frequencies in which SI(f)S_I (f) is nearly constant, hence allowing characterization of the current noise by the effective Fano factor F\equiv S_I(f)/2e \left. For sufficiently large conductor samples and low temperatures, the Fano factor is suppressed below the Schottky value (F=1), scaling with the length LL of the conductor as F=(Lc/L)αF = (L_c / L)^{\alpha}. The exponent α\alpha is significantly affected by the Coulomb interaction effects, changing from α=0.76±0.08\alpha = 0.76 \pm 0.08 when such effects are negligible to virtually unity when they are substantial. The scaling parameter LcL_c, interpreted as the average percolation cluster length along the electric field direction, scales as LcE(0.98±0.08)L_c \propto E^{-(0.98 \pm 0.08)} when Coulomb interaction effects are negligible and LcE(1.26±0.15)L_c \propto E^{-(1.26 \pm 0.15)} when such effects are substantial, in good agreement with estimates based on the theory of directed percolation.Comment: 19 pages, 7 figures. Fixed minor typos and updated reference

    A Numerical Study of Transport and Shot Noise at 2D Hopping

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    We have used modern supercomputer facilities to carry out extensive Monte Carlo simulations of 2D hopping (at negligible Coulomb interaction) in conductors with the completely random distribution of localized sites in both space and energy, within a broad range of the applied electric field EE and temperature TT, both within and beyond the variable-range hopping region. The calculated properties include not only dc current and statistics of localized site occupation and hop lengths, but also the current fluctuation spectrum. Within the calculation accuracy, the model does not exhibit 1/f1/f noise, so that the low-frequency noise at low temperatures may be characterized by the Fano factor FF. For sufficiently large samples, FF scales with conductor length LL as (Lc/L)α(L_c/L)^{\alpha}, where α=0.76±0.08<1\alpha=0.76\pm 0.08 < 1, and parameter LcL_c is interpreted as the average percolation cluster length. At relatively low EE, the electric field dependence of parameter LcL_c is compatible with the law LcE0.911L_c\propto E^{-0.911} which follows from directed percolation theory arguments.Comment: 17 pages, 8 figures; Fixed minor typos and updated reference

    Dronedarone in high-risk permanent atrial fibrillation

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    BACKGROUND: Dronedarone restores sinus rhythm and reduces hospitalization or death in intermittent atrial fibrillation. It also lowers heart rate and blood pressure and has antiadrenergic and potential ventricular antiarrhythmic effects. We hypothesized that dronedarone would reduce major vascular events in high-risk permanent atrial fibrillation. METHODS: We assigned patients who were at least 65 years of age with at least a 6-month history of permanent atrial fibrillation and risk factors for major vascular events to receive dronedarone or placebo. The first coprimary outcome was stroke, myocardial infarction, systemic embolism, or death from cardiovascular causes. The second coprimary outcome was unplanned hospitalization for a cardiovascular cause or death. RESULTS: After the enrollment of 3236 patients, the study was stopped for safety reasons. The first coprimary outcome occurred in 43 patients receiving dronedarone and 19 receiving placebo (hazard ratio, 2.29; 95% confidence interval [CI], 1.34 to 3.94; P = 0.002). There were 21 deaths from cardiovascular causes in the dronedarone group and 10 in the placebo group (hazard ratio, 2.11; 95% CI, 1.00 to 4.49; P = 0.046), including death from arrhythmia in 13 patients and 4 patients, respectively (hazard ratio, 3.26; 95% CI, 1.06 to 10.00; P = 0.03). Stroke occurred in 23 patients in the dronedarone group and 10 in the placebo group (hazard ratio, 2.32; 95% CI, 1.11 to 4.88; P = 0.02). Hospitalization for heart failure occurred in 43 patients in the dronedarone group and 24 in the placebo group (hazard ratio, 1.81; 95% CI, 1.10 to 2.99; P = 0.02). CONCLUSIONS: Dronedarone increased rates of heart failure, stroke, and death from cardiovascular causes in patients with permanent atrial fibrillation who were at risk for major vascular events. Our data show that this drug should not be used in such patients. (Funded by Sanofi-Aventis; PALLAS ClinicalTrials.gov number, NCT01151137.) Copyright © 2011 Massachusetts Medical Society. All rights reserved.published_or_final_versio

    Analisis Gaya Kepemimpinan Kepala Sekolah untuk Meningkatkan Mutu Pendidikan dengan Keterbatasan Animo Siswa

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    This study aims to describe: 1) the implementation of the headmaster's leadership in carrying out its functions to improve the quality of education with the limitations of student animo.; 2) the role of the headmaster's leadership to face obstacles in improving the quality of education with the limitation of student animo; 3) solutions made by the headmaster in overcoming obstacles to improving the quality of education with the limitations of student animo. This type of research is a qualitative research with a case study research design. The 2 informants of this study are the headmaster and teachers. Data collection techniques used were observation, interviews, and documentation. The validity of this research data uses triangulation of techniques and sources. The results showed: 1) The implementation of the headmaster's leadership when responding to the occurrence of limited student animo is to use a democratic leadership style. The leadership style then changes when the headmaster as a leader must act decisively in the implementation of policies and work procedures so that authoritarianism, directive, coaching, supporting and delegating. 2) The role of the headmaster's leadership in dealing with quality improvement constraints with the limitation of student interest is the provider of protection, the provider of security and comfort, the provider of assistance, and the provider of guidance. The situation of not meeting the target of students, is a condition that must be faced by all components of the school, and the headmaster is the main component that has the biggest role in school management, including the management of teachers. 3) The solution made by the headmaster in overcoming obstacles to improving the quality of education with the limitation of student interest is to affirm his position as a leader, as responsible person, and as the main actor who drives the improvement of the quality of school education. The headmaster conducts supervision of learning, the headmaster tries to identify problems by looking directly into the field, communicating with teachers, sharing experiences with teachers, and direct dialogue with students

    Upaya Kepolisian Dalam Penanggulangan Kenakalan Remaja di Surakarta

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    Adolescence is a stage of life that is transitional and unstable. Juvenile delinquency is an aberrant behavior or unlawful. Types are also varied, such as drug abuse, criminal acts, to sexual harassment. It can be triggered by a variety of demands and stress. For example, finding a job in a competitive environment, develop relationships with others, demands for self-organization, and adaptation to technology. In addition, many teenagers experiencing anxiety and stress related to personal safety and security. Juvenile delinquency cause material loss and inner misery both to the actors themselves as well as for victims. For the various juvenile delinquency prevention efforts both penal and non-penal made by various parties, including the police. Abatement is penal in the form it processes juvenile offenders legally. In non penal overcome by the police in the form of counseling, patrol, coaching, as well as raids. This study uses descriptive non-doctrinal. Using this type of primary and secondary data. Data collection techniques used through interviews and literature study. By using qualitative data analysis. Based on the results of research and discussion, it can be concluded that the efforts of the police in the prevention of juvenile delinquency in the form of preventive and repressive. Abatement preventive care such as certain places, patrol, counseling, conveying messages of social order, traffic management, safety riding training. Abatement repressive form of diversion, manufacture affidavit, coaching, penilangan, rehabilitation. Barriers that prevent the police in tackling juvenile delinquency is difficult to reach an agreement in an effort kinship, verdict too light, insufficient rule of law, ignorance of the law being in force, counseling schedule incompatibility with the agenda in schools, lack of legal awareness in berlalu- traffic, lack of coordination with the Dispora and the public

    Wind-driven ventilation improvement with plan typology alteration: a CFD case study of traditional Turkish architecture

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    Aligned with achieving the goal of net-zero buildings, the implementation of energy-saving techniques in minimizing energy demands is proving more vital than at any time. As practical and economic options, passive strategies in ventilation developed over thousands of years have shown great potential for the reduction of residential energy demands, which are often underestimated in modern building’s construction. In particular, as a cost-effective passive strategy, wind-driven ventilation via windows has huge potential in the enhancement of the indoor air quality (IAQ) of buildings while simultaneously reducing their cooling load. This study aims to investigate the functionality and applicability of a common historical Turkish architectural element called “Cumba” to improve the wind-driven ventilation in modern buildings. A case study building with an archetypal plan and parameters was defined as a result of a survey over 111 existing traditional samples across Turkey. Buildings with and without Cumba were compared in different scenarios by the development of a validated CFD microclimate model. The results of simulations clearly demonstrate that Cumba can enhance the room’s ventilation rate by more than two times while harvesting wind from different directions. It was also found that a flexible window opening strategy can help to increase the mean ventilation rate by 276%. Moreover, the room’s mean air velocity and ventilation rate could be adjusted to a broad range of values with the existence of Cumba. Thus, this study presents important findings about the importance of plan typology in the effectiveness of wind-driven ventilation strategies in modern dwellings

    Molecular survey on vector-borne pathogens in clinically healthy stray cats in Zaragoza (Spain)

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    Background In Europe, feline vector-borne infections are gaining importance because of the changing climate, expanding habitats of potential vectors and expanding pathogen reservoirs. The main objective of this study was to assess the prevalence of vector-borne pathogens (VBPs) in stray cats in Zaragoza, Spain, and to investigate potential risk factors for infection, including feline leukaemia virus (FeLV) and feline immunodeficiency virus (FIV). Methods Blood samples from stray cats presented to the veterinary faculty in Zaragoza between February 2020 and 2022 were tested by polymerase chain reaction (PCR) for the presence of Anaplasma phagocytophilum, Anaplasma platys, Bartonella henselae, Ehrlichia canis, Rickettsia spp., haemotropic Mycoplasma spp., Hepatozoon spp., Leishmania infantum, piroplasms and microfilariae at the LABOKLIN laboratory. The cats were also tested for FeLV and FIV by PCR. Results Nearly half of the cats (158/332, 47.6%) were positive for at least one VBP. Hepatozoon spp. were detected in 25.6%, haemotropic Mycoplasma spp. in 22.9%, B. henselae in 9.3% and L. infantum in 2.1% of the cats. Male sex had a statistically significant association with test results for haemotropic Mycoplasma spp. (odds ratio 1.38 [1.21;1.57]); regionality with Hepatozoon spp., B. henseale and FIV; and seasonality with Hepatozoon spp., haemotropic Mycoplasma spp., L. infantum and FeLV (P ≤ 0.05 each). A strong positive correlation was reported for the amount of rainfall and the number of cats that tested positive for Hepatozoon spp. (ρ = 753, P = 0.05). None of the cats tested positive for A. phagocytophilum, A. platys, E. canis, Rickettsia spp., piroplasms, or microfilariae. Co-infections with multiple VBPs were detected in 56 out of 332 cats (16.9%). Thirty-one of the 332 cats included in the study (9.3%) tested positive for FeLV (6.9%) and for FIV (3.6%). In 20/31 cats (64.5%) that tested positive for FeLV/FIV, coinfections with VBP were detected (P = 0.048, OR 2.15 [0.99; 4.64]). Conclusions VBPs were frequently detected in stray cats in Zaragoza. In particular, regionality and seasonality had a statistically significant association with PCR results for most VBPs included in the study

    University–industry collaboration: using meta-rules to overcome barriers to knowledge transfer

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    This is the final version of the article. Available from Springer Verlag via the DOI in this record.University–industry knowledge transfer is an important source wealth of creation for all partners; however, the practical management of this activity within universities is often hampered by procedural rigidity either through the absence of decision-making protocols to reconcile conflicting priorities or through the inconsistent implementation of existing policies. This is problematic, since it can impede operational effectiveness, prevent inter-organisational knowledge-creation and hamper organisational learning. This paper addresses this issue by adopting a cross-discipline approach and presenting meta-rules as a solution to aid organisational decision making. It is proposed that meta-rules can help resolve tensions arising from conflicting priorities between academics, knowledge transfer offices and industry and help facilitate strategic alignment of processes and policies within and between organisations. This research contributes to the growing debate on the strategic challenges of managing knowledge transfer and presents meta-rules as a practical solution to facilitate strategic alignment of internal and external stakeholder tensions. Meta-rules has previously only been applied in a computer intelligence context however, this research proves the efficacy of meta rules in a university–industry knowledge transfer context. This research also has practical implications for knowledge transfer office managers who can use meta-rules to help overcome resource limitations, conflicting priorities and goals of diverse internal and external stakeholders

    Molecular survey on vector-borne pathogens in clinically healthy stray cats in Zaragoza (Spain)

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    Background In Europe, feline vector-borne infections are gaining importance because of the changing climate, expanding habitats of potential vectors and expanding pathogen reservoirs. The main objective of this study was to assess the prevalence of vector-borne pathogens (VBPs) in stray cats in Zaragoza, Spain, and to investigate potential risk factors for infection, including feline leukaemia virus (FeLV) and feline immunodeficiency virus (FIV). Methods Blood samples from stray cats presented to the veterinary faculty in Zaragoza between February 2020 and 2022 were tested by polymerase chain reaction (PCR) for the presence of Anaplasma phagocytophilum, Anaplasma platys, Bartonella henselae, Ehrlichia canis, Rickettsia spp., haemotropic Mycoplasma spp., Hepatozoon spp., Leishmania infantum, piroplasms and microfilariae at the LABOKLIN laboratory. The cats were also tested for FeLV and FIV by PCR. Results Nearly half of the cats (158/332, 47.6%) were positive for at least one VBP. Hepatozoon spp. were detected in 25.6%, haemotropic Mycoplasma spp. in 22.9%, B. henselae in 9.3% and L. infantum in 2.1% of the cats. Male sex had a statistically significant association with test results for haemotropic Mycoplasma spp. (odds ratio 1.38 [1.21;1.57]); regionality with Hepatozoon spp., B. henseale and FIV; and seasonality with Hepatozoon spp., haemotropic Mycoplasma spp., L. infantum and FeLV (P ≤ 0.05 each). A strong positive correlation was reported for the amount of rainfall and the number of cats that tested positive for Hepatozoon spp. (ρ = 753, P = 0.05). None of the cats tested positive for A. phagocytophilum, A. platys, E. canis, Rickettsia spp., piroplasms, or microfilariae. Co-infections with multiple VBPs were detected in 56 out of 332 cats (16.9%). Thirty-one of the 332 cats included in the study (9.3%) tested positive for FeLV (6.9%) and for FIV (3.6%). In 20/31 cats (64.5%) that tested positive for FeLV/FIV, coinfections with VBP were detected (P = 0.048, OR 2.15 [0.99; 4.64]). Conclusions VBPs were frequently detected in stray cats in Zaragoza. In particular, regionality and seasonality had a statistically significant association with PCR results for most VBPs included in the study
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