550 research outputs found

    BER of MRC for M-QAM with imperfect channel estimation over correlated Nakagami-m fading

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    In this contribution, we provide an exact BER analysis for M-QAM transmission over arbitrarily correlated Nakagami-m fading channels with maximal-ratio combining (MRC) and imperfect channel estimation at the receiver. Assuming an arbitrary joint fading distribution and a generic pilot-based channel estimation method, we derive an exact BER expression that involves an expectation over (at most) 4 variables, irrespective of the number of receive antennas. The resulting BER expression includes well-known PDFs and the PDF of only the norm of the channel vector. In order to obtain the latter PDF for arbitrarily correlated Nakagami-m fading, several approaches from the literature are discussed. For identically distributed and arbitrarily correlated Nakagami-m channels with integer m, we present several BER performance results, which are obtained from numerical evaluation and confirmed by straightforward computer simulations. The numerical evaluation of the exact BER expression turns out to be much less time-consuming than the computer simulations

    Lifting the Anterior Midcheek and Nasolabial Fold:Introduction to the Melo Fat Pad Anatomy and Its Role in Longevity and Recurrence

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    BACKGROUND: A limitation of current facelift techniques is the early postoperative reappearance of anterior midcheek laxity associated with recurrence of the nasolabial fold (NLF).OBJECTIVES: This study was undertaken to examine the regional anatomy of the anterior midcheek and NLF with a focus on explaining the early recurrence phenomenon and to explore the possibility of alternative surgical methods that prolong NLF correction.METHODS: Fifty cadaver heads were studied (16 embalmed, 34 fresh, mean age 75 years). Following preliminary dissections and macro-sectioning, a series of standardized layered dissections were performed, complemented by histology, sheet plastination and micro-CT. Mechanical testing of the melo fat pad (MFP) and skin was performed to gain insight on which structure is responsible for transmission of the lifting tension in a composite facelift procedure.RESULTS: Anatomical dissections, sheet plastination and micro-CT demonstrated the three-dimensional architecture and borders of the MFP. Histology of a lifted midcheek demonstrated that a composite MFP lift causes a change in connective tissue organization from a hanging-down pattern into a pulled upward pattern suggesting traction on the skin. Mechanical testing confirmed that, in a composite lift, despite the sutures being placed directly into the deep aspect of the MFP, the lifting tension distal to the suture is transmitted through the skin and not through the MFP.CONCLUSIONS: As a composite midcheek lift is usually performed, it is the skin and not the MFP itself, that bears the load of the non-dissected tissues distal to the lifting suture. For this reason, early recurrence of the NLF occurs following skin relaxation in the postoperative period. Accordingly, specific surgical procedures for remodeling the MFP should be explored, possibly in combination with volume restoration of the fat and bone, for more lasting improvement of the NLF.</p

    Marine Reserve Design: Optimal Size, Habitats, Species Affinities, Diversity, And Ocean Microclimate

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    The design of marine reserves is complex and fraught with uncertainty. However, protection of critical habitat is of paramount importance for reserve design. We present a case study as an example of a reserve design based on fine-scale habitats, the affinities of exploited species to these habitats, adult mobility, and the physical forcing affecting the dynamics of the habitats. These factors and their interaction are integrated in an algorithm that determines the optimal size and location of a marine reserve for a set of 20 exploited species within five different habitats inside a large kelp forest in southern California. The result is a reserve that encompasses similar to 42% of the kelp forest. Our approach differs fundamentally from many other marine reserve siting methods in which goals of area, diversity, or biomass are targeted a priori. Rather, our method was developed to determine how large a reserve must be within a specific area to protect a self-sustaining assemblage of exploited species. The algorithm is applicable across different ecosystems, spatial scales, and for any number of species. The result is a reserve in which habitat value is optimized for a predetermined set of exploited species against the area left open to exploitation. The importance of fine-scale habitat definitions for the exploited species off La Jolla is exemplified by the spatial pattern of habitats and the stability of these habitats within the kelp forest, both of which appear to be determined by ocean microclimate

    Herpes Simplex Virus Type 1 Penetrates the Basement Membrane in Human Nasal Respiratory Mucosa

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    Background: Herpes simplex virus infections are highly prevalent in humans. However, the current therapeutics suffer important drawbacks such as limited results in neonates, increasing occurrence of resistance and impeded treatment of stromal infections. Remarkably, interactions of herpesviruses with human mucosa, the locus of infection, remain poorly understood and the underlying mechanisms in stromal infection remain controversial. Methodology/Principal Findings: A human model consisting of nasal respiratory mucosa explants was characterised. Viability and integrity were examined during 96 h of cultivation. HSV1-mucosa interactions were analysed. In particular, we investigated whether HSV1 is able to reach the stroma. Explant viability and integrity remained preserved. HSV1 induced rounding up and loosening of epithelial cells with very few apoptotic and necrotic cells observed. Following 16-24 h of infection, HSV1 penetrated the basement membrane and replicated in the underlying lamina propria. Conclusions/Significance: This human explant model can be used to study virus-mucosa interactions and viral mucosal invasion mechanisms. Using this model, our results provide a novel insight into the HSV1 stromal invasion mechanism and for the first time directly demonstrate that HSV1 can penetrate the basement membrane

    Strategies for fitting nonlinear ecological models in R, AD Model Builder, and BUGS

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    Summary: 1. Ecologists often use nonlinear fitting techniques to estimate the parameters of complex ecological models, with attendant frustration. This paper compares three open-source model fitting tools and discusses general strategies for defining and fitting models. 2. R is convenient and (relatively) easy to learn, AD Model Builder is fast and robust but comes with a steep learning curve, while BUGS provides the greatest flexibility at the price of speed. 3. Our model-fitting suggestions range from general cultural advice (where possible, use the tools and models that are most common in your subfield) to specific suggestions about how to change the mathematical description of models to make them more amenable to parameter estimation. 4. A companion web site (https://groups.nceas.ucsb.edu/nonlinear-modeling/projects) presents detailed examples of application of the three tools to a variety of typical ecological estimation problems; each example links both to a detailed project report and to full source code and data

    Depression in Patients with Mastocytosis: Prevalence, Features and Effects of Masitinib Therapy

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    Depression in patients with mastocytosis is often reported but its prevalence and characteristics are not precisely described. In addition, the impact of therapies targeting mast cells proliferation, differentiation and degranulation on psychic symptoms of depression have never been investigated. Our objective was to determine the prevalence and to describe features of depression in a large cohort of mastocytosis patients (n = 288) and to investigate the therapeutic impact of the protein kinase inhibitor masitinib in depression symptoms. The description of depression was based on the analysis of a database with Hamilton scores using Principal Component Analysis (PCA). Efficacy of masitinib therapy was evaluated using non parametric Wilcoxon test for paired data within a three months period (n = 35). Our results show that patients with indolent mastocytosis present an elevated prevalence of depression (64%). Depression was moderate in 56% but severe in 8% of cases. Core symptoms (such as psychic anxiety, depressed mood, work and interests) characterized depression in mastocytosis patients. Masitinib therapy was associated with significant improvement (67% of the cases) of overall depression, with 75% of recovery cases. Global Quality of Life slightly improved after masitinib therapy and did not predicted depression improvement. In conclusion, depression is very frequent in mastocytosis patients and masitinib therapy is associated with the reduction its psychic experiences. We conclude that depression in mastocytosis may originate from processes related to mast cells activation. Masitinib could therefore be a useful treatment for mastocytosis patients with depression and anxiety symptoms
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