429 research outputs found

    A New Spatial Block-Correlation Model for Fluid Antenna Systems

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    Powered by position-flexible antennas, the emerging fluid antenna system (FAS) technology is postulated as a key enabler for massive connectivity in 6G networks. The free movement of antenna elements enables the opportunistic minimization of interference, allowing several users to share the same radio channel without the need of precoding. However, the true potential of FAS is still unknown due to the extremely high spatial correlation of the wireless channel between very close-by antenna positions. To unveil the multiplexing capabilities of FAS, proper (simple yet accurate) modeling of the spatial correlation is prominently needed. Realistic classical models such as Jakes’s are prohibitively complex, rendering intractable analyses, while state-of-the-art approximations often are too simplistic and poorly accurate. Aiming to fill this gap, we here propose a general framework to approximate spatial correlation by block-diagonal matrices, motivated by the well-known block fading assumption and by statistical results on large correlation matrices. The proposed block-correlation model makes the performance analysis possible, and tightly approximates the results obtained with realistic models (Jakes’s and Clarke’s). Our framework is leveraged to analyze fluid antenna multiple access (FAMA) systems, evaluating their performance for both one- and two-dimensional fluid antennas

    Vacuum Instabilities with a Wrong-Sign Higgs-Gluon-Gluon Amplitude

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    The recently discovered 125 GeV boson appears very similar to a Standard Model Higgs, but with data favoring an enhanced h to gamma gamma rate. A number of groups have found that fits would allow (or, less so after the latest updates, prefer) that the h-t-tbar coupling have the opposite sign. This can be given meaning in the context of an electroweak chiral Lagrangian, but it might also be interpreted to mean that a new colored and charged particle runs in loops and produces the opposite-sign hGG amplitude to that generated by integrating out the top, as well as a contribution reinforcing the W-loop contribution to hFF. In order to not suppress the rate of h to WW and h to ZZ, which appear to be approximately Standard Model-like, one would need the loop to "overshoot," not only canceling the top contribution but producing an opposite-sign hGG vertex of about the same magnitude as that in the SM. We argue that most such explanations have severe problems with fine-tuning and, more importantly, vacuum stability. In particular, the case of stop loops producing an opposite-sign hGG vertex of the same size as the Standard Model one is ruled out by a combination of vacuum decay bounds and LEP constraints. We also show that scenarios with a sign flip from loops of color octet charged scalars or new fermionic states are highly constrained.Comment: 20 pages, 8 figures; v2: references adde

    TESLA Technical Design Report Part III: Physics at an e+e- Linear Collider

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    The TESLA Technical Design Report Part III: Physics at an e+e- Linear ColliderComment: 192 pages, 131 figures. Some figures have reduced quality. Full quality figures can be obtained from http://tesla.desy.de/tdr. Editors - R.-D. Heuer, D.J. Miller, F. Richard, P.M. Zerwa

    Conditions of work and dermatitis in workers exposed to chemical risks by cement

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    This research was carried out in order to identify the working conditions in workers exposed to cement in a cement factory in the city of Cartagena. Through different tools it was possible to carry out the diagnosis of the working conditions and to identify the hazards to which the workers of the company are exposed when being in direct contact with the cement; in this way it was possible to know that the dermatitis that were manifesting the workers has its direct relation with this chemical and therefore to be able to establish those measures tending to ensure the complete state of health of the workers. The type of research carried out is descriptive-qualitative, the applied methodology used as a closed questions survey tool, it was obtained as a result that 70% of the respondents did not use personal protection elements when handling cement, so can say that there is a considerable number of people exposed, which increases the likelihood that they may suffer contact dermatitis, through this the different preventive measures for working and health conditions among the employees of the cement company were raised

    Procedimiento alternativo para la integración del COAAAS-L de la Batería Mistral de la Brigada con el COAAAS-M

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    Este trabajo estudia una parte del enlace entre distintos órganos desde los cuales seejerce el mando y control de una unidad de Artillería Antiaérea, la Batería Mistral.La Batería Mistral se concibe como una unidad orgánica preparada para repeler amenazasaéreas (aeronaves) que vuelen a muy baja cota. Para poder realizar sus funciones, se articulade tal manera que el mando y control de la batalla antiaérea lo ejerce el sistema COAAAS-L,que cuenta con todos los medios necesarios para ello.No obstante, el sistema COAAASL queda limitado si se requiere integrar los sistemas dearmas de la Batería Mistral en el Sistema de Defensa Aéreo. Para ello, el órgano que hace deeslabón entre el Sistema de Defensa Aéreo y el COAAAS-L es el COAAAS-M. Este sistemahace de escalón superior y se enlaza con su escalón inferior, el sistema COAAAS-L.La integración entre ambos COAAAS se materializa actualmente mediante el enlace víaradio PR4G v3. Este enlace se traduce en una malla de fonía entre ambos escalones y unamalla de datos, con la cual intercambian información táctica, posición de trazas aéreas, alertas,estado del sistema de armas, etc. La radio PR4G v3 funciona bien en este enlace pero quedamuy limitada la distancia a la que es capaz de enlazar una radio con otra, limitando así lamaniobra de la Batería Mistral y el enlace entre ambos escalones.En la idea que expone el JEMAD del entorno operativo 2035, se han determinado algunascaracterísticas de empleo de las fuerzas armas y se ha determinado que habrá un enemigotecnológicamente más desarrollado y que se tendrá que trabajar en ambienteselectrónicamente degradados. Esta idea, junto a la idea de obtener un mayor alcance hace quese deba buscar una alternativa robusta a la radio PR4G v3 que permita enlazar ambosCOAAAS con seguridad y a mayor distancia.En esta memoria se propondrán métodos de enlace alternativos a la radio PR4G v3 talescomo la radio HARRIS, que representa el enlace HF ,terminales satélites TLX-50 y TLB-50 queutilizan los satélites disponibles para el uso de las fuerzas armadas, y un teléfono IP, querepresenta un medio de tecnología civil. Se estudiarán los requisitos necesarios de laintegración COAAAS-L/COAAAS-M, si cada alternativa los satisface y como implementar cadaalternativa mediante un estudio del software y hardware de cada una. Seguidos a este estudio,se utilizarán herramientas como los análisis DAFO y el método de decisión multicriterio AHPpara elegir la mejor alternativa.ha determinado que la mejor alternativa al uso de la radio PR4G v3 en ambos COAAAS esel terminal satélite TLX-50, en dotación en el Ejército de Tierra. Es un medio de transmisionesligero, fácil de transportar y operar que se conecta con un satélite espacial y que brinda lacapacidad de enviar datos y fonía a la vez que un alcance prácticamente ilimitado.<br /

    Applied interpolation methodology with GIS used for artisanal fishing zoning in Bahía Magdalena, Mexico

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    Objective: To limit the artisanal fishing zones in the water mirror of Magdalena Bay, by means of interpolation. Design/methodology/approach: Through surveys, social, economic and biological production data, wich are collected from a sample of 56 artisanal fishing cooperatives. The data is integrated into a relational database with geospatial reference and geostatistically processed with interpolation methods using a geographic information system. Results: Four zoning maps based on the interpolation of the variables target species, fishing effort, extraction volume and sale value. Limitations on study/implications: The remoteness and difficult access to the study area. Findings/conclusions: The methodology can be used at the national level and generate a limitation of the priority zones for artisanal fishing in Mexico, contributing to decision making and management plans that can consider the variables of the fishermen's social life

    Why Are Outcomes Different for Registry Patients Enrolled Prospectively and Retrospectively? Insights from the Global Anticoagulant Registry in the FIELD-Atrial Fibrillation (GARFIELD-AF).

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    Background: Retrospective and prospective observational studies are designed to reflect real-world evidence on clinical practice, but can yield conflicting results. The GARFIELD-AF Registry includes both methods of enrolment and allows analysis of differences in patient characteristics and outcomes that may result. Methods and Results: Patients with atrial fibrillation (AF) and ≥1 risk factor for stroke at diagnosis of AF were recruited either retrospectively (n = 5069) or prospectively (n = 5501) from 19 countries and then followed prospectively. The retrospectively enrolled cohort comprised patients with established AF (for a least 6, and up to 24 months before enrolment), who were identified retrospectively (and baseline and partial follow-up data were collected from the emedical records) and then followed prospectively between 0-18 months (such that the total time of follow-up was 24 months; data collection Dec-2009 and Oct-2010). In the prospectively enrolled cohort, patients with newly diagnosed AF (≤6 weeks after diagnosis) were recruited between Mar-2010 and Oct-2011 and were followed for 24 months after enrolment. Differences between the cohorts were observed in clinical characteristics, including type of AF, stroke prevention strategies, and event rates. More patients in the retrospectively identified cohort received vitamin K antagonists (62.1% vs. 53.2%) and fewer received non-vitamin K oral anticoagulants (1.8% vs . 4.2%). All-cause mortality rates per 100 person-years during the prospective follow-up (starting the first study visit up to 1 year) were significantly lower in the retrospective than prospectively identified cohort (3.04 [95% CI 2.51 to 3.67] vs . 4.05 [95% CI 3.53 to 4.63]; p = 0.016). Conclusions: Interpretations of data from registries that aim to evaluate the characteristics and outcomes of patients with AF must take account of differences in registry design and the impact of recall bias and survivorship bias that is incurred with retrospective enrolment. Clinical Trial Registration: - URL: http://www.clinicaltrials.gov . Unique identifier for GARFIELD-AF (NCT01090362)

    A922 Sequential measurement of 1 hour creatinine clearance (1-CRCL) in critically ill patients at risk of acute kidney injury (AKI)

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    Population differentiation and historical demography of the threatened snowy plover Charadrius nivosus (Cassin, 1858)

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    Delineating conservation units is a complex and often controversial process that is particularly challenging for highly vagile species. Here, we reassess population genetic structure and identify those populations of highest conservation value in the threatened snowy plover (Charadrius nivosus, Cassin, 1858), a partial migrant shorebird endemic to the Americas. We use four categories of genetic data—mitochondrial DNA (mtDNA), microsatellites, Z-linked and autosomal single nucleotide polymorphisms (SNPs)—to: (1) assess subspecies delineation and examine population structure (2) compare the sensitivity of the different types of genetic data to detect spatial genetic patterns, and (3) reconstruct demographic history of the populations analysed. Delineation of two traditionally recognised subspecies was broadly supported by all data. In addition, microsatellite and SNPs but not mtDNA supported the recognition of Caribbean snowy plovers (C. n. tenuirostris) and Floridian populations (eastern C. n. nivosus) as distinct genetic lineage and deme, respectively. Low migration rates estimated from autosomal SNPs (m < 0.03) reflect a general paucity of exchange between genetic lineages. In contrast, we detected strong unidirectional migration (m = 0.26) from the western into the eastern nivosus deme. Within western nivosus, we found no genetic differentiation between coastal Pacific and inland populations. The correlation between geographic and genetic distances was weak but significant for all genetic data sets. All demes showed signatures of bottlenecks occurring during the past 1000 years. We conclude that at least four snowy plover conservation units are warranted: in addition to subspecies nivosus and occidentalis, a third unit comprises the Caribbean tenuirostris lineage and a fourth unit the distinct eastern nivosus deme

    Non-motor symptom burden in patients with Parkinson's disease with impulse control disorders and compulsive behaviours: results from the COPPADIS cohort.

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    The study was aimed at analysing the frequency of impulse control disorders (ICDs) and compulsive behaviours (CBs) in patients with Parkinson's disease (PD) and in control subjects (CS) as well as the relationship between ICDs/CBs and motor, nonmotor features and dopaminergic treatment in PD patients. Data came from COPPADIS-2015, an observational, descriptive, nationwide (Spain) study. We used the validated Questionnaire for Impulsive-Compulsive Disorders in Parkinson's Disease-Rating Scale (QUIP-RS) for ICD/CB screening. The association between demographic data and ICDs/CBs was analyzed in both groups. In PD, this relationship was evaluated using clinical features and treatment-related data. As result, 613 PD patients (mean age 62.47 ± 9.09 years, 59.87% men) and 179 CS (mean age 60.84 ± 8.33 years, 47.48% men) were included. ICDs and CBs were more frequent in PD (ICDs 12.7% vs. 1.6%, p < 0.001; CBs 7.18% vs. 1.67%, p = 0.01). PD patients had more frequent previous ICDs history, premorbid impulsive personality and antidepressant treatment (p < 0.05) compared with CS. In PD, patients with ICDs/CBs presented younger age at disease onset, more frequent history of previous ICDs and premorbid personality (p < 0.05), as well as higher comorbidity with nonmotor symptoms, including depression and poor quality of life. Treatment with dopamine agonists increased the risk of ICDs/CBs, being dose dependent (p < 0.05). As conclusions, ICDs and CBs were more frequent in patients with PD than in CS. More nonmotor symptoms were present in patients with PD who had ICDs/CBs compared with those without. Dopamine agonists have a prominent effect on ICDs/CBs, which could be influenced by dose
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