1,659 research outputs found

    Uniform optical gain as a non-Hermitian control knob

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    Non-Hermitian optics utilizes judicious engineering of the spatial and spectral distribution of gain and loss in order to tailor the behavior of photonic systems in ways that could not be achieved by modulating only the real part of the refractive index. In this respect, a question that has never been addressed is whether a uniform distribution of gain or loss can also lead to nontrivial non-Hermitian effects in linear systems, beyond just signal amplification or decay. Here, we investigate this problem and demonstrate that the application of uniform gain to a symmetric photonic molecule (PM) can reverse the optical energy distribution inside the structure. For a PM composed of two coupled resonators, this translates into changing the optical energy distribution inside the resonators. For a PM formed through scattering or defect-induced intermodal coupling in a ring resonator, the applied gain, despite being uniform and symmetric, can impose a strong chirality and switch the direction of light propagation from dominantly clockwise to dominantly counterclockwise. These predictions are confirmed by using both coupled mode formalism and full-wave finite-element simulations. Our work establishes a different direction in the field of non-Hermitian optics where interesting behavior can be engineered not only by unbalancing the non-Hermitian parameter but also by changing its average value - a feature that was overlooked in previous works

    A comprehensive analysis of genetic risk for metabolic syndrome in the Egyptian population via allele frequency investigation and Missense3D predictions

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    Abstract Diabetes mellitus (DM) represents a major health problem in Egypt and worldwide, with increasing numbers of patients with prediabetes every year. Numerous factors, such as obesity, hyperlipidemia, and hypertension, which have recently become serious concerns, affect the complex pathophysiology of diabetes. These metabolic syndrome diseases are highly linked to genetic variability that drives certain populations, such as Egypt, to be more susceptible to developing DM. Here we conduct a comprehensive analysis to pinpoint the similarities and uniqueness among the Egyptian genome reference and the 1000-genome subpopulations (Europeans, Ad-Mixed Americans, South Asians, East Asians, and Africans), aiming at defining the potential genetic risk of metabolic syndromes. Selected approaches incorporated the analysis of the allele frequency of the different populations’ variations, supported by genotypes’ principal component analysis. Results show that the Egyptian’s reference metabolic genes were clustered together with the Europeans’, Ad-Mixed Americans’, and South-Asians’. Additionally, 8563 variants were uniquely identified in the Egyptian cohort, from those, two were predicted to cause structural damage, namely, CDKAL1: 6_21065070 (A > T) and PPARG: 3_12351660 (C > T) utilizing the Missense3D database. The former is a protein coding gene associated with Type 2 DM while the latter is a key regulator of adipocyte differentiation and glucose homeostasis. Both variants were detected heterozygous in two different Egyptian individuals from overall 110 sample. This analysis sheds light on the unique genetic traits of the Egyptian population that play a role in the DM high prevalence in Egypt. The proposed analysis pipeline -available through GitHub- could be used to conduct similar analysis for other diseases across populations

    Stochasticity and Non-locality of Time

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    We present simple classical dynamical models to illustrate the idea of introducing a stochasticity with non-locality into the time variable. For stochasticity in time, these models include noise in the time variable but not in the "space" variable, which is opposite to the normal description of stochastic dynamics. Similarly with respect to non-locality, we discuss delayed and predictive dynamics which involve two points separated on the time axis. With certain combinations of fluctuations and non-locality in time, we observe a ``resonance'' effect. This is an effect similar to stochastic resonance, which has been discussed within the normal context of stochastic dynamics, but with different mechanisms. We discuss how these models may be developed to fit a broader context of generalized dynamical systems where fluctuations and non-locality are present in both space and time.Comment: 12 pages, 5 figures, Accepted and to appear in Physica A. (reference corrected for ver. 2

    Early Continence and Extravasation After Open Retropubic Radical Prostatectomy – Interrupted vs Continuous Suturing for Vesicourethral Anastomosis

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    Purpose: To compare running suture (RS) and interrupted suture (IS) of vesicourethral anastomosis (VUA) during open retropubic radical prostatectomy (RRP) on early urinary continence and extravasation. Patients and methods: Single center analysis of 211 patients who underwent RRP performed by a single surgeon during 2008 to 2017 was retrospectively analyzed. For VUA, we used the standard interrupted suture technique (n=100) with a 3-0 PDS suture. The RS (n=111) was performed with 12-bite suture using 3-0 PDS. The primary endpoints were extravasation and early continence. Demographic and peri-operative data were collected and analyzed using Pearson's chi-square, t-Test and Mann-Whitney U-test. A binary logistic regression analysis was carried out to explore predictors that affected early continence after catheter removal. Results: The rates of early urinary incontinence (UI) were 7.7% vs 42.2% (p<0.001). The duration of catheterization and hospitalization was significantly shorter in the interrupted group (4 days vs 5 days, p<0.001 and 5 days vs 6 days, p<0.001). The groups did not differ significantly in body mass index or prostate volume. There were older patients and higher PSA levels in the group with RS technique. No significant difference was found in the postoperative extravasation rates between both groups (13.5% vs 12%, p=0.742). Conclusion: Running vesicourethral anastomosis increased the rate of early urinary incontinence. Both anastomosis techniques provided a similar rate of postoperative urine extravasation. VUA should only be one of the many criteria that must be considered for the preservation of urinary continence of patients after RRP

    Xanthan gum as an alternative to replace fat for coating and flavoring the extruded snacks

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    Food industries adapt their products and processes to the needs and desires of consumers. Extruded snacks include 10–20% fat sprinkled to fix flavors, seasonings, and salt. Considering the need to flavor snacks and simultaneously reduce the intake of calories, a polysaccharide is proposed in this study as a fat replacer. Impact of aqueous xanthan gum (Xg) solutions (0.25, 0.5, 1.0%) under two pH conditions (3.5 and 7.0) on structural and sensory characteristics of extruded snacks was analyzed. Rheological features of the coating solutions, as flow behaviour and viscoelastic profile (storage and loss moduli), were assessed. Texture analysis, to evaluate the snacks firmness and moisture content, water activity, retraction, and agglomeration index of the coated snacks, were also evaluated. Results for the aqueous Xg coatings were very encouraging showing good coating properties, not damaging the texture of the extrudates or causing agglomeration. Sensory analysis reflected a good overall acceptability of these snacks, as compared to oil-coated snacks. Therefore, xanthan gum should be used by the industry, to replace fat, on extruded snacks flavor coating solutionsinfo:eu-repo/semantics/publishedVersio

    Symptomatic Acute Hepatitis C in Egypt: Diagnosis, Spontaneous Viral Clearance, and Delayed Treatment with 12 Weeks of Pegylated Interferon Alfa-2a

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    The aim of this study was to estimate the proportion of spontaneous viral clearance (SVC) after symptomatic acute hepatitis C and to evaluate the efficacy of 12 weeks of pegylated interferon alfa-2a in patients who did not clear the virus spontaneously.Patients with symptomatic acute hepatitis C were recruited from two "fever hospitals" in Cairo, Egypt. Patients still viremic three months after the onset of symptoms were considered for treatment with 12 weeks of pegylated interferon alfa-2a (180 microg/week).Between May 2002 and February 2006, 2243 adult patients with acute hepatitis were enrolled in the study. The SVC rate among 117 patients with acute hepatitis C was 33.8% (95%CI [25.9%-43.2%]) at three months and 41.5% (95%CI [33.0%-51.2%]) at six months. The sustained virological response (SVR) rate among the 17 patients who started treatment 4-6 months after onset of symptoms was 15/17 = 88.2% (95%CI [63.6%-98.5%]).Spontaneous viral clearance was high (41.5% six months after the onset of symptoms) in this population with symptomatic acute hepatitis C. Allowing time for spontaneous clearance should be considered before treatment is initiated for symptomatic acute hepatitis C
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