296 research outputs found

    The Influence of Geometrical Shape Changes on Wave Overtopping: a Laboratory and SPH Numerical Study

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    This paper presents laboratory investigations of four “retrofit” suggestions for attenuating the overtopping from vertical seawall. Two-dimensional physical model experiments were performed on a vertical seawall with a 1:20 sloping foreshore. Additionally, a Lagrangian, particle based SPH methodology was employed to simulate the wave hydrodynamics and overtopping for the recurve configuration. The experimental and numerical results confirm satisfactory performance. For the tested configurations in the laboratory, the mean overtopping discharges decreased over 60% and maximum individual discharge decreased 40% on recurve wall under both impulsive and non-impulsive conditions. A significant reduction was also observed in mitigating overtopping discharge by using model vegetation and reef breakwater, while diffraction pillar was not found satisfactory

    Evaluation of response to preoperative chemotherapy versus surgery alone in gastroesophageal cancer: Tumor resectability, pathologic results and post-operative complications

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    Gastroesophageal cancer is one of the most common types of cancer worldwide. Despite significant developments in management, 5-year survival in the developing world is less than 20 percent. Due to restricted research about the impact of preoperative chemotherapy (POC) on tumor resection, pathological response and postoperative complications in Iran, we designed and implemented the present retrospective cross- sectional study on 156 patients with gastroesophageal cancer (GEc) between 2013 and 2015 at Shariati Hospital of Tehran. Two groups were included, the first group had previously received preoperative chemotherapy and the second group had only undergone surgery. All patients were followed for at least one year after the operation in terms of tumor recurrence, relapse free survival and one-year survival. The two groups were eventually compared regarding tumor resection, pathological response, postoperative complications, recurrence rate and survival. The mean age was 66.5± 7.3 years and 78 percent were male. The tumor resectability, pathological response and postoperative complications in the group which received POC were 93.5, 21.8 and 12.8, respectively, and in the surgery alone group figures for tumor resection and postoperative complications were 76 and 29.5, respectively. Also based on our study the 5-year survival in the POC group was better (79.5 vs. 66.5). Using standard neoadjuvant regimens (preoperative chemotherapy/ chemoradiotherapy) beforesurgery could increase tumor resectability, pathological response, and improve the general status of the patients. Therefore using POC may be recommended over surgery alone. © 2016, Asian Pacific Journal of Cancer Prevention

    Phenotypic and genotypic characteristics of tetracycline resistant Acinetobacter baumannii isolates from nosocomial infections at Tehran hospitals

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    Objective(s): To date, the most important genes responsible for tetracycline resistance among Acinetobacter baumannii isolates have been identified as tet A and tet B. This study was carried out to determine the rate of resistance to tetracycline and related antibiotics, and mechanisms of resistance. Materials and Methods: During the years 2010 and 2011, a total of 100 A. baumannii isolates were recovered from patients in different hospitals of Tehran, Iran. Antimicrobial susceptibility to tetracycline, minocycline, doxicycline and tigecycline was evaluated by E-test. Polymerase chain reaction (PCR) of the tet A and tet B genes was performed using specific primers, after which the isolates were subjected to Repetitive Extragenic Palindromic-PCR (PCR) to identify the major genotypes. Results: Of all isolates, 89 were resistant to tetracycline (MIC50 = 32 mu g/ml, MIC90 = 512 mu g/ml). Minocycline with the resistant rate of 35 (MIC50 = 16 mu g/ml, MIC90 = 32 mu g/ml) and doxicycline with the resistant rate of 25 (MIC50 = 16 mu g/ml, MIC90= 32 mu g/ml) have a good activity against A. baumannii isolates. All isolates were sensitive to tigecycline. Frequencies of tet B and tet A genes and coexistence of tet A and tet B among the isolates resistant to tetracycline, were 87.6, 2.2 and 1.1, respectively. Distribution of REP-types among A. baumannii isolates was types A (40), B (30), C (10), D (5) and E (5). Conclusion: It seems that tet A and tet B genes play an important role in the induction of resistance towards tetracyclines used in this study. It is suggested that further studies focus on other antimicrobial drugs and combinations in order to achieve a successful therapy against multi drug resistance (MDR) A. baumannii strains in Iran

    Gender-based difference in early mortality among patients with ST-segment elevation myocardial infarction: insights from Kermanshah STEMI Registry.

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    Introduction: This study aimed to evaluate the in-hospital mortality of patients with ST-segment elevation myocardial infarction (STEMI), according to gender and other likely risk factors. Methods: This study reports on data relating to 1,484 consecutive patients with STEMI registered from June 2016 to May 2018 in the Western Iran STEMI Registry. Data were collected using a standardized case report developed by the European Observational Registry Program (EORP). The relationship between in-hospital mortality and potential predicting variables was assessed multivariable logistic regression. Differences between groups in mortality rates were compared using chi-square tests and independent t-tests. Results: Out of the 1484 patients, 311(21%) were female. Women were different from men in terms of age (65.8 vs. 59), prevalence of hypertension (HTN) (63.7% vs. 35.4%), diabetes mellitus (DM) (37.7% vs. 16.2%), hypercholesterolemia (36.7% vs. 18.5%) and the history of previous congestive heart failure (CHF) (6.6% vs. 3.0%). Smoking was more prevalent among men (55.9% vs. 13.2%). Although the in-hospital mortality rate was higher in women (11.6% vs. 5.5%), after adjusting for other risk factors, female sex was not an independent predictor for in-hospital mortality. Multivariable analysis identified that age and higher Killip class (≥II) were significantly associated with in-hospital mortality rate. Conclusion: In-hospital mortality after STEMI in women was higher than men. However, the role of sex as an independent predictor of mortality disappeared in regression analysis. The gender based difference in in-hospital mortality after STEMI may be related to the poorer cardiovascular disease (CVD) risk factor profile of the women

    Long-term symptoms and function after war-related lower limb amputation: A national cross-sectional study

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    Objective: The aim of this study was to document long-term symptoms and functional results following war-related knee disarticulation, trans-femoral amputation, and hip disarticulation. Methods: An observational cross-sectional study was conducted in a 7-day recreational camp in Iran. One thousand patients with unilateral hip disarticulation, trans-femoral amputation and knee disarticulation due to war-related injuries were invited to undergo a thorough physical examination. Among the invited persons, 58.7 (587 subjects) responded to our invitations. A complete examination related to phantom pain, phantom sensation, stump pain, back pain, and sound limb joints pain with a self-constructed questionnaire was performed. In addition, Amputee Mobility Predictor (AMP) instrument with a prosthesis was completed to assess the function of patients. Results: The mean duration of time since amputation was 22 years. The most common symptoms reported by participants were phantom sensation (82), back pain (69), and phantom pain (63). In addition, total scores of AMP with a prosthesis in persons with knee disarticulation and trans-femoral amputations were 20.8 and 28, respectively. The knee disarticulation was associated with higher scores of AMP with a prosthesis compared to transfemoral amputation (p < 0.01). Conclusion: The results of this study showed that patients with lower limb amputation suffer from significant clinical and functional problems. The findings may be useful to adopt new strategies in planning rehabilitation programs to improve quality of life and health status of patients with war-related lower limb amputation. Level of Evidence: This study was conducted in level of evidence IV. © 201

    A NOS1AP gene variant is associated with a paradoxical increase of the QT-interval shortening effect of digoxin

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    Digoxin is characterized by a small therapeutic window and a QT-interval shortening effect. Moreover, it has been shown that the genetic variants of the nitric oxide synthase-1 adaptor protein (NOS1AP) gene are associated with QT-interval prolongation. We investigated whether the rs10494366 variant of the NOS1AP gene decreases the QT-interval shortening effect of digoxin in patients using this drug. We included 10,057 individuals from the prospective population-based cohort of the Rotterdam Study during a median of 12.2 (interquartile range (IQR) 6.7-18.1) years of follow-up. At study entry, the mean age was 64 years and almost 59% of participants were women. A total of 23,179 ECGs were longitudinally recorded, of which 334 ECGs were from 249 individuals on digoxin therapy. The linear mixed model analysis was used to estimate the effect of the rs10494366 variant on the association between digoxin use and QT-interval duration, adjusted for age, sex, RR interval, diabetes, heart failure, and history of myocardial infarction. In non-users of digoxin, the GG genotype was associated with a significant 6.5 ms [95% confidence interval (CI) 5.5; 7.5] longer QT-interval duration than the TT variant. In current digoxin users, however, the GG variant was associated with a significantly -23.9 [95%CI -29.5; -18.5] ms shorter mean QT-interval duration than in those with the TT variant with -15.9 [95%CI -18.7; -13.1]. This reduction was strongest in the high digoxin dose category [≥0.250 mg/day] with the GG genotype group, with -40.8 [95%CI -52.5; -29.2] ms changes compared to non-users. Our study suggests that the minor homozygous GG genotype group of the NOS1AP gene rs10494366 variant is associated with a paradoxical increase of the QT-interval shortening effect of digoxin in a population of European ancestry

    Noncommutative Topological Half-flat Gravity

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    We formulate a noncommutative description of topological half-flat gravity in four dimensions. BRST symmetry of this topological gravity is deformed through a twisting of the usual BRST quantization of noncommutative gauge theories. Finally it is argued that resulting moduli space of instantons is characterized by the solutions of a noncommutative version of the Plebanski's heavenly equation.Comment: 12+1 pages, revtex4, no figure

    Achieving higher photoabsorption than group III-V semiconductors in silicon using photon-trapping surface structures

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    The photosensitivity of silicon is inherently very low in the visible electromagnetic spectrum, and it drops rapidly beyond 800 nm in near-infrared wavelengths. Herein, we have experimentally demonstrated a technique utilizing photon-trapping surface structures to show a prodigious improvement of photoabsorption in one-micrometer-thin silicon, surpassing the inherent absorption efficiency of gallium arsenide for a broad spectrum. The photon-trapping structures allow the bending of normally incident light by almost ninety degrees to transform into laterally propagating modes along the silicon plane. Consequently, the propagation length of light increases, contributing to more than an order of magnitude improvement in absorption efficiency in photodetectors. This high absorption phenomenon is explained by FDTD analysis, where we show an enhanced photon density of states while substantially reducing the optical group velocity of light compared to silicon without photon-trapping structures, leading to significantly enhanced light-matter interactions. Our simulations also predict an enhanced absorption efficiency of photodetectors designed using 30 and 100-nanometer silicon thin films that are compatible with CMOS electronics. Despite a very thin absorption layer, such photon-trapping structures can enable high-efficiency and high-speed photodetectors needed in ultra-fast computer networks, data communication, and imaging systems with the potential to revolutionize on-chip logic and optoelectronic integration.Comment: 24 pages, 4 figure

    Effective superpotentials for compact D5-brane Calabi-Yau geometries

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    For compact Calabi-Yau geometries with D5-branes we study N=1 effective superpotentials depending on both open- and closed-string fields. We develop methods to derive the open/closed Picard-Fuchs differential equations, which control D5-brane deformations as well as complex structure deformations of the compact Calabi-Yau space. Their solutions encode the flat open/closed coordinates and the effective superpotential. For two explicit examples of compact D5-brane Calabi-Yau hypersurface geometries we apply our techniques and express the calculated superpotentials in terms of flat open/closed coordinates. By evaluating these superpotentials at their critical points we reproduce the domain wall tensions that have recently appeared in the literature. Finally we extract orbifold disk invariants from the superpotentials, which, up to overall numerical normalizations, correspond to orbifold disk Gromov-Witten invariants in the mirror geometry.Comment: 55 pages; v2: references added, typos correcte
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