1,878 research outputs found

    Neutron transition strengths of 21+2^+_1 states in the neutron rich Oxygen isotopes determined from inelastic proton scattering

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    A coupled-channel analysis of the 18,20,22^{18,20,22}O(p,p)(p,p') data has been performed to determine the neutron transition strengths of 21+^+_1 states in Oxygen targets, using the microscopic optical potential and inelastic form factor calculated in the folding model. A complex density- and \emph{isospin} dependent version of the CDM3Y6 interaction was constructed, based on the Brueckner-Hatree-Fock calculation of nuclear matter, for the folding model input. Given an accurate isovector density dependence of the CDM3Y6 interaction, the isoscalar (δ0\delta_0) and isovector (δ1\delta_1) deformation lengths of 21+^+_1 states in 18,20,22^{18,20,22}O have been extracted from the folding model analysis of the (p,p)(p,p') data. A specific NN-dependence of δ0\delta_0 and δ1\delta_1 has been established which can be linked to the neutron shell closure occurring at NN approaching 16. The strongest isovector deformation was found for 21+^+_1 state in 20^{20}O, with δ1\delta_1 about 2.5 times larger than δ0\delta_0, which indicates a strong core polarization by the valence neutrons in 20^{20}O. The ratios of the neutron/proton transition matrix elements (Mn/MpM_n/M_p) determined for 21+^+_1 states in 18,20^{18,20}O have been compared to those deduced from the mirror symmetry, using the measured B(E2)B(E2) values of 21+^+_1 states in the proton rich 18^{18}Ne and 20^{20}Mg nuclei, to discuss the isospin impurity in the 21+2^+_1 excitation of the A=18,T=1A=18,T=1 and A=20,T=2A=20,T=2 isobars.Comment: Version accepted for publication in Physical Review

    Pairing effect on the giant dipole resonance width at low temperature

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    The width of the giant dipole resonance (GDR) at finite temperature T in Sn-120 is calculated within the Phonon Damping Model including the neutron thermal pairing gap determined from the modified BCS theory. It is shown that the effect of thermal pairing causes a smaller GDR width at T below 2 MeV as compared to the one obtained neglecting pairing. This improves significantly the agreement between theory and experiment including the most recent data point at T = 1 MeV.Comment: 8 pages, 5 figures to be published in Physical Review

    The Insula and Its Epilepsies

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    Insular seizures are great mimickers of seizures originating elsewhere in the brain. The insula is a highly connected brain structure. Seizures may only become clinically evident after ictal activity propagates out of the insula with semiology that reflects the propagation pattern. Insular seizures with perisylvian spread, for example, manifest first as throat constriction, followed next by perioral and hemisensory symptoms, and then by unilateral motor symptoms. On the other hand, insular seizures may spread instead to the temporal and frontal lobes and present like seizures originating from these regions. Due to the location of the insula deep in the brain, interictal and ictal scalp electroencephalogram (EEG) changes can be variable and misleading. Magnetic reso- nance imaging, magnetic resonance spectroscopy, magnetoencephalography, positron emission tomography, and single-photon computed tomography imaging may assist in establishing a diagnosis of insular epilepsy. Intracranial EEG recordings from within the insula, using stereo-EEG or depth electrode techniques, can prove insular seizure origin. Seizure onset, most commonly seen as low-voltage, fast gamma activity, however, can be highly localized and easily missed if the insula is only sparsely sampled. Moreover, seizure spread to the contralateral insula and other brain regions may occur rapidly. Extensive sampling of the insula with multiple electrode trajectories is necessary to avoid these pitfalls. Understanding the functional organization of the insula is helpful when interpreting the semiology produced by insular seizures. Electrical stimulation mapping around the central sulcus of the insula results in paresthesias, while stimulation of the posterior insula typically produces painful sensations. Visceral sensations are the next most common result of insular stimulation. Treatment of insular epilepsy is evolving, but poses challenges. Surgical resections of the insula are effective but risk significant morbidity if not carefully planned. Neurostimulation is an emerging option for treatment, especially for seizures with onset in the posterior insula. The close association of the insula with marked autonomic changes has led to interest in the role of the insula in sudden unexpected death in epilepsy and warrants additional study with larger patient cohorts

    Laser induced electron diffraction: a tool for molecular orbital imaging

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    We explore the laser-induced ionization dynamics of N2 and CO2 molecules subjected to a few-cycle, linearly polarized, 800\,nm laser pulse using effective two-dimensional single active electron time-dependent quantum simulations. We show that the electron recollision process taking place after an initial tunnel ionization stage results in quantum interference patterns in the energy resolved photo-electron signals. If the molecule is initially aligned perpendicular to the field polarization, the position and relative heights of the associated fringes can be related to the molecular geometrical and orbital structure, using a simple inversion algorithm which takes into account the symmetry of the initial molecular orbital from which the ionized electron is produced. We show that it is possible to extract inter-atomic distances in the molecule from an averaged photon-electron signal with an accuracy of a few percents

    Highly accurate step counting at variouswalking states using low-cost inertial measurement unit support indoor positioning system

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    © 2018 by the authors. Licensee MDPI, Basel, Switzerland. Accurate step counting is essential for indoor positioning, health monitoring systems, and other indoor positioning services. There are several publications and commercial applications in step counting. Nevertheless, over-counting, under-counting, and false walking problems are still encountered in these methods. In this paper, we propose to develop a highly accurate step counting method to solve these limitations by proposing four features: Minimal peak distance, minimal peak prominence, dynamic thresholding, and vibration elimination, and these features are adaptive with the user’s states. Our proposed features are combined with periodicity and similarity features to solve false walking problem. The proposed method shows a significant improvement of 99.42% and 96.47% of the average of accuracy in free walking and false walking problems, respectively, on our datasets. Furthermore, our proposed method also achieves the average accuracy of 97.04% on public datasets and better accuracy in comparison with three commercial step counting applications: Pedometer and Weight Loss Coach installed on Lenovo P780, Health apps in iPhone 5s (iOS 10.3.3), and S-health in Samsung Galaxy S5 (Android 6.01)

    Barriers and Facilitators to the Integration of Depression Services in Primary Care in Vietnam: A Mixed Methods Study

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    Background  Although the prevalence of depression in Vietnam is on par with global rates, services for depression are limited. The government of Vietnam has prioritized enhancing depression care through primary healthcare (PHC) and efforts are currently underway to test and scale-up psychosocial interventions throughout the country. With these initiatives in progress, it is important to understand implementation factors that might influence the successful integration of depression services into PHC. As the implementers of these new interventions, primary care providers (PHPs) are well placed to provide important insight into implementation factors affecting the integration of depression services into PHC. This mixed-methods study examines factors at the individual, organizational and structural levels that may act as barriers and facilitators to the integration of depression services into PHC in Vietnam from the perspective of PHPs. Methods  Data collection took place in Hanoi, Vietnam in 2014. We conducted semi-structured interviews with PHPs (n = 30) at commune health centres and outpatient clinics in one rural and one urban district of Hanoi. Theoretical thematic analysis was used to analyse interview data. We administered an online survey to PHPs at n = 150 randomly selected communes across Hanoi. N = 226 PHPs responded to the survey. We used descriptive statistics to describe the study variables acting as barriers and facilitators and used a chi-square test of independence to indicate statistically significant (p < .05) associations between study variables and the profession, location and gender of PHPs. Results  Individual-level barriers include low level of knowledge and familiarity with depression among PHPs. Organizational barriers include low resource availability in PHC and low managerial discretion. Barriers at the structural level include limited mental health training among all PHPs and the existing programmatic structure of PHC in Vietnam, which sets mental health apart from general services. Facilitators at the individual level include positive attitudes among PHPs towards people with depression and interest in undergoing enhanced training in depression service delivery. Conclusions  While facilitating factors at the individual level are encouraging, considerable barriers at the structural level must be addressed to ensure the successful integration of depression services into PHC in Vietnam

    Acceptance patterns and decision-making for human papillomavirus vaccination among parents in Vietnam: an in-depth qualitative study post-vaccination

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    BACKGROUND: The GAVI Alliance’s decision in late 2011 to invite developing countries to apply for funding for human papillomavirus (HPV) vaccine introduction underscores the importance of understanding levels of HPV vaccine acceptance in developing country settings. In this paper, we present findings from qualitative research on parents’ rationales for vaccinating or not vaccinating their daughters (vaccine acceptance) and their decision-making process in the context of an HPV vaccination demonstration project in Vietnam (2008–2009). METHODS: We designed a descriptive qualitative study of HPV vaccine acceptability among parents of girls eligible for vaccination in four districts of two provinces in Vietnam(a). The study was implemented after each of two years of vaccinations was completed. In total, 133 parents participated in 16 focus group discussions and 27 semi-structured interviews. RESULTS: Focus group discussions and in-depth interviews with parents of girls vaccinated revealed that they were generally very supportive of immunization for disease prevention and of vaccinating girls against HPV. The involvement of the National Expanded Program of Immunization in the demonstration project lent credibility to the HPV vaccine, contributing to high levels of acceptance. For parents who declined participation, concerns about side effects, the possibility that the vaccine was experimental, and the possible impact of the vaccine on future fertility rose to the surface. In terms of the decision-making process, many parents exhibited ‘active decision-making,’ reaching out to friends, family, and opinion leaders for guidance prior to making their decision. CONCLUSION: Vietnam’s HPV vaccination experience speaks to the importance of close collaboration with the government to make the most of high levels of trust, and to reduce suspicions about new vaccines that may arise in the context of vaccine introduction in developing country settings

    Kohn-Sham scheme for frequency dependent linear response

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    We study the Kohn-Sham scheme for the calculation of the steady state linear response to a harmonic perturbation that is turned on adiabatically. Although in general the exact time dependent exchange-correlation potential cannot be expressed as the functional derivative of a universal functional due to the so-called causality paradox, we show that for a harmonic perturbation the exchange-correlation part of the first-order Kohn-Sham potential vs(1)(r)cos(ωt)v_s^{(1)}(r) \cos(\omega t) is given by vxc(1)(r)=δKxc(2)/δn(1)(r)v_{xc}^{(1)}(r) = \delta K_{xc}^{(2)}/\delta n^{(1)}(r). Kxc(2)K_{xc}^{(2)} is the exchange-correlation part of the second-order quasienergy Kv(2)K_v^{(2)}. The Frenkel variation principle implies a stationary principle for the second-order quasienergy. We also find an analogous stationary principle and KS scheme in the time dependent extension of one-matrix functional theory, in which the basic variable is the one-matrix (one-body reduced density matrix).Comment: 11 pages; minor corrections; details adde

    Hygiene and microbial contamination along the pork value chain in Vietnam

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    In Vietnam, pork accounts for 75% of total meat consumed daily at households. However, pork may contain high levels of microbial contamination such as Salmonella and Escherichia coli which might cause harm to consumers. To determine microbial contamination along the pork value chain, we collected 216 samples from 72 pig farms (floor swab, drinking and waste water), 545 from 49 slaughterhouses (carcass swab, lymph node, rectal feces, floor swab and washing water) and 514 from 220 pork shops in the informal markets (pork cuts, ground pork and cutting board swab) in two provinces of Vietnam (Hung Yen and Nghe An). Samples were analyzed to detect qualitatively and quantitatively Salmonella and E. coli. Overall prevalence of Salmonella combined from all types of above mentioned samples at pig farms, slaughterhouses and pork shops were 35%, 30% and 37%, respectively. Salmonella contamination in the final product (pork at market) was 45% and an average concentration of 9 MPN/g was recorded. E. coli average load along different points of the chain was 5.3 ± 1.4 (farm floor swabs), 2.9 ± 0.9 (carcass swabs), 3.1 ± 1.0 (slaughterhouse floor swabs), and 3.3 ± 1.1 (market shop cutting board swabs) logCFU/cm2, whereas pork from the market had 3.4 ± 0.9 logCFU/g. Demonstrated high levels of Salmonella in the final product (pork at market) induces the potential health risks for the consumers. High values for E. coli indicates general poor hygiene along the chain. Appropriate hygiene practices and management are required to achieve better pork quality and reduce the risk for the consumer. These data will serve as inputs for health risk assessments related to pork consumption
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