729 research outputs found

    On the relation between boundary proposals and hidden symmetries of the extended pre-big bang quantum cosmology

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    A framework associating quantum cosmological boundary conditions to minisuperspace hidden symmetries has been introduced in \cite{7}. The scope of the application was, notwithstanding the novelty, restrictive because it lacked a discussion involving realistic matter fields. Therefore, in the herein letter, we extend the framework scope to encompass elements from a scalar-tensor theory in the presence of a cosmological constant. More precisely, it is shown that hidden minisuperspace symmetries present in a pre-big bang model suggest a process from which boundary conditions can be selected.Comment: 15 pages, no figures, to appear in European Physical Journal

    Exciton Spin Hall Effect In Arc-Shaped Strained WSe<sub>2</sub>

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    Generating a pure spin current using electrons, which have degrees of freedom beyond spin, such as electric charge and valley index, presents challenges. In response, we propose a novel mechanism based on intervalley exciton dynamics in {\em arc-shaped} strained transition metal dichalcogenides (TMDs) to achieve the {\em exciton spin Hall effect} in an electrically insulating regime, without the need for an external electric field. The interplay between strain gradients and strain-induced pseudomagnetic fields results in a net Lorentz force on long-lived intervalley excitons in WSe2_2, carrying non-zero spin angular momentum. This process generates an exciton-mediated pure spin Hall current, resulting in opposite-sign spin accumulations and local magnetization on the two sides of the single-layer arc-shaped TMD. We demonstrate that the magnetic field induced by spin accumulation, at approximately mT\sim {\rm mT}, can be detected using techniques such as superconducting quantum interference magnetometry or spatially-resolved magneto-optical Faraday and Kerr rotations

    Non Celiac Gluten Sensitivity and Diagnostic Challenges

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    Non-celiac gluten sensitivity (NCGS), also referred to as non-celiac wheat sensitivity (NCWS), is a clinical syndrome characterized by both intestinal and extra-intestinal symptoms responsive to the withdrawal of gluten-containing food from the diet. The aim of this review is to summarize recent advances in research and provide a brief overview of the history of the condition for the benefit of professionals working in gastroenterology. Academic databases such as PubMed and Google Scholar were searched using key words such as ”non-celiac gluten sensitivity”, “gluten related disorders”, and the studies outlined in reference page were selected and analysed. Most of the analysed studiers agree that NCGS would need to be diagnosed only after exclusion of celiac disease and wheat allergy, and that a reliable serological marker is not available presently. The mechanisms causing symptoms in NCGS after gluten ingestion are largely unknown, but recent advances have begun to offer novel insights. The estimated prevalence of NCGS, at present, varies between 0.6 and 6%. There is an overlap between irritable bowel syndrome and NCGS with regard to the similarity of gastrointestinal symptoms. The histologic characteristics of NCGS are still under investigation, ranging from normal histology to slight increase in the number of T lymphocytes in the superficial epithelium of villi. Positive response to gluten free diet for a limited period (e.g., 6 weeks), followed by the reappearance of symptoms after gluten challenge appears, at this moment, to be the best approach for confirming diagnosis. The Salerno expert criteria may help to diagnose NCGS accurately in particular for research purposes but it has limited applicability in clinical practice

    Studying the effect of manager’s Strategic Thinking on Corporate entrepreneurship

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    The purpose of this research is to explore the effect of managers' strategic thinking on corporate entrepreneurship. To this end, one main hypothesis and five secondary hypotheses were proposed. This study is descriptive-applicable and Lidka studies (1998) were employed to measure managers' strategic thinking and Robins and Kutler's questionnaire (1996) was used to measure corporate entrepreneurship. The statistical population included 118 managers and employees of a manufacturing company in Kermanshah industrial estate. The research sample was equal to 90 using Cochran formula. The results disclosed that managers' strategic thinking has a positive and significant effect on corporate entrepreneurship and all hypotheses were confirme

    Microscopic Enteritis; Clinical Features and Correlations with Symptoms

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    Aim: To assess the clinical characteristic of CD as well as correlation of symptoms and the degrees of intestinal mucosal lesions in Iranian children. Background: Microscopic Enteritis (Marsh 0-II) is associated with malabsorption. Patients and methods: From August 2005 to September 2009, 111 cases with malabsorption and classical gastrointestinal symptoms were evaluated. Results: The mean (±SD) age of children with CD was 4.9±3.5 years (range, 6 month - 16 years) and the mean duration of symptoms was 8 ± 20.5 months. 50 cases (45%) were female and 61 cases (55%) were male. The most common clinical presentation was failure to thrive in 72%, chronic diarrhea in 65.8% and Iron deficiency anemia in 59.5%. Sensitivity of EMA was 100% in patients with Marsh IIIb and Marsh IIIc. EMA was also positive in 77% of cases with Marsh 0, 18% in Marsh I, 44% in Marsh II and 81.8% in patients with Marsh IIIa. Conclusion: Histopathology did not reflect the severity of gluten sensitivity. This would suggest that the degree of intestinal mucosal damage might not be a reliable prognostic factor. Significant symptoms can be present with minor histological change on biopsy

    Review paper: Introduction of pediatric balance therapy in children with vestibular dysfunction: Review of indications, mechanisms, and key exercises

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    The vestibular system is important for the development of normal movement reactions, motion tolerance, and motor control for postural alignment, balance, and vision. A vestibular system that is damaged by disease or injury in childhood can have a major impact on a child's development. In addition, the emergence of vestibular lesions may also lead to cognitive deficits, including attention deficit. Despite the advances in testing and documentation of vestibular deficits in children, the vestibular problems continue to be an overlooked entity. Many children do not receive treatment that could significantly improve function and address the developmental delays caused by vestibular disorders. Vestibular rehabilitation therapy (VRT) has been defined as an effective modality for most individuals with disorders of the vestibular or central balance system disorders. The basis for the success of VRT is the use of existing neural mechanisms in the human brain for adaptation, plasticity, and compensation. The vestibular system cannot be considered as a separate entity ignoring other balance subsystems. Hence, a modified VRT program, named pediatric balance therapy with special modifications in exercises, was developed for children with vestibular disorders, in accordance to the whole balance system

    Therapeutic Potential of Microvesicles in Cell Therapy and Regenerative Medicine of Ocular Diseases With an Especial Focus on Mesenchymal Stem Cells-Derived Microvesicles

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    These days, mesenchymal stem cells (MSCs), because of immunomodulatory and pro-angiogenic abilities, are known as inevitable factors in regenerative medicine and cell therapy in different diseases such as ocular disorder. Moreover, researchers have indicated that exosome possess an essential potential in the therapeutic application of ocular disease. MSC-derived exosome (MSC-DE) have been identified as efficient as MSCs for treatment of eye injuries due to their small size and rapid diffusion all over the eye. MSC-DEs easily transfer their ingredients such as miRNAs, proteins, and cytokines to the inner layer in the eye and increase the reconstruction of the injured area. Furthermore, MSC-DEs deliver their immunomodulatory cargos in inflamed sites and inhibit immune cell migration, resulting in improvement of autoimmune uveitis. Interestingly, therapeutic effects were shown only in animal models that received MSC-DE. In this review, we summarized the therapeutic potential of MSCs and MSC-DE in cell therapy and regenerative medicine of ocular diseases
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