Suppression of cyclic prefix in down-link LTE like systems to increase capacity

The proceeding at : 77th Vehicular Technology Conference (VTC Spring), took place 2013, June 02-05, in Dresden (Germany).In this paper it is presented a proposal to increase the capacity of Down-Link (DL) transmissions in Long Term Evolution (LTE) like systems based on Multiple-Input Multiple-Output (MIMO)-Orthogonal Frequency Division Multiplexing (OFDM). The augment of the data rate is achieved with the total or partial suppression of the Cyclic Prefix (CP), which requires the use of a variable number of samples without conveying any information. The proposal is based on an iterative cancellation of the main impairments that the CP suppression supposes, the Inter Symbol and Inter Carrier Interferences. The interference mitigation procedure demands adequate channel estimations obtained in two different stages. Firstly, this new scheme requires the utilization of a preamble symbol appended to the beginning of the data transmission, which enables an initial Maximum Likelihood channel estimation. Secondly, time-variant channels will be estimated using a Least Squares estimator by the use of scattered pilots within the LTE frame structure. Through simulations it has been demonstrated that, despite the interferences arisen due to the CP suppression, our proposal attains adequate channel estimations which converge to theoretical bounds and the overall system obtains values of Bit Error Rate similar to the ideal situation of not suppressing the CP. It is also presented that considering the typical values of CP in the LTE standard the increment of the capacity employing this strategy can range between 7% and 25%.This work has been partly funded by the Spanish national projects GRE3NSYST (TEC2011-29006-C03-03) and COMONSENS (CSD2008-00010).Publicad

Iterative Joint Estimation Procedure for Channel and Frequency Offset in Multi-Antenna OFDM Systems With an Insufficient Cyclic Prefix

This paper addresses a strategy to improve the joint channel and frequency offset (FO) estimation in multi-antenna systems, widely known as multiple-input-multiple-output orthogonal frequency-division multiplexing (MIMO-OFDM), in the presence of intersymbol interference (ISI) and intercarrier interference (ICI) occasioned by an insufficient cyclic prefix (CP). The enhancement is attained by the use of an iterative joint estimation procedure (IJEP) that successively cancels the interferences located in the preamble of the OFDM frame, which is used for the joint estimation and initially contains the interferences due to a CP shorter than the channel length. The IJEP requires at certain steps a proper iterative interference cancellation algorithm, which makes use of an initial FO compensation and channel estimation obtained due to the use of a symmetric sequence in the preamble. After the iterative cancellation of interferences, the procedure performs an additional joint channel and FO estimation whose mean square error converges to the Cramer-Rao bound (CRB). Later on, this subsequent joint estimation permits the removal of the interferences in the data part of the frame, which are also due to an insufficient CP, in the same iterative fashion but saving iterations compared with the use of other estimation strategies. The appraisal of the procedure has been performed by assessing the convergence of the simulated estimators to the CRB as a function of the number of iterations. Additionally, simulations for the evaluation of the bit error rate (BER) have been carried out to probe how the utilization of the proposed IJEP clearly improves the performance of the system. It is concluded that, with a reduced number of iterations in the preamble, the IJEP converges to the theoretical bounds, thus reducing the disturbances caused by a hard wireless channel or a deliberately insufficient CP.This work was supported in part by the Spanish na-tional projects GRE3N-SYST (TEC2011-29006-C03-03) and COMONSENS (CSD2008-00010).Publicad

Role of the dental surgeon in the early detection of adults with underlying HIV infection / AIDS

A review is made of the late diagnosis of human immunodeficiency virus (HIV) infection, a subject of growing interest in public health. It has been estimated that in Europe 30% of all HIV-infected people are unaware of their seropositive condition, and this in turn is associated with a poorer long-term disease prognosis and an increased risk of transmission to other individuals. The role of the dental surgeon in this context could be of great importance, since there are many oral lesions that can suggest the existence of underlying infection. The study also addresses the controversial subject of rapid HIV testing, and whether these tests should be performed on a routine basis in the dental clinic, or whether it is preferable to refer the patient to a specialized center

Epidemiology of HIV infection in immigrants in Spain: information sources, characteristics, magnitude and tendencies.

[ES] En España, la proporción de inmigrantes en la población general y entre las personas con infección por VIH es creciente en los últimos años. Sin embargo, la información sobre las tendencias temporales de la epidemia en inmigrantes y sobre sus características sociodemográficas, epidemiológicas y clínicas es escasa, y está fraccionada en diversas fuentes de información que cubren aspectos complementarios. Los objetivos de este trabajo fueron analizar las fuentes de información disponibles que permiten caracterizar la epidemiología de la infección por VIH en los inmigrantes en España, y describir la situación actual de la epidemia en este grupo de población a partir de la información disponible en dichas fuentes. [EN] Lately Spain, the proportion of immigrants has increased in both general and HIV-infected populations. Nevertheles, data on the temporal trends of the epidemic in immigrants and on their sociodemographic, epidemiologic and clinical characteristics are scarce and are scattered in various information sources that cover complementary aspects of this issue. The objectives of the present study were to analyze the available information sources that allow the epidemiology of HIV infection in immigrants in Spain to be studied, and to describe the current situation of HIV infection in immigrants, based on the available information sources.Este estudio ha sido financiado por la Red de Sida (Redes Temáticas de Investigación Cooperativa, RD06/006).S

Fondos sobre literatura árabe moderna existentes en la Facultad de Filosofía y Letras de la Universidad de Granada

En esta primera parte del catálogo se han vaciado los fondos de la biblioteca del Departamento de Lengua y Literatura Arabes, dividiéndolos en siete partes: lista de obras de literatura crítica en sus distintas vertientes (narrativa, poesía, teatro), reseñas críticas de obras estén o no en el Departamento, pues pensamos que son una fuente estimable de conocimiento bibliográfico. Siguen dos nuevos apartados referentes a la producción original y a las traducciones de obras literarias respectivamente. Finaliza el catálogo con tres apartados sobre publicaciones socio-históricas, fuentes bibliográficas y obras de difícil clasificación que pensamos pueden tener relación con el tema y que nosotros incluimos para facilitar la labor de búsqueda bibliográfica de las personas que estén comenzando a investigar

Assessing quality of life in people with HIV in Spain: psychometric testing of the Spanish version of WHOQOL-HIV-BREF

BACKGROUND: The assessment of health-related quality of life (HRQoL) in people living with HIV (PLHIV) has become crucial to evidence-based practice. The goals of this study are to analyze the psychometric properties and evidence of the validity of the Spanish version of WHOQOL-HIV-BREF in a sample of PLHIV in Spain and to examine the more impaired HRQoL facets and dimensions and identify the PLHIV who show the most vulnerable profile. METHODS: A total of 1462 PLHIV participated in an observational cross-sectional ex-post-facto study. Data were collected at 33 Spanish sites through an online survey. In addition to measuring HRQoL, the study used other tools to measure treatment adherence (CEAT-VIH 2.0 version), psychological well-being (GHQ-12) and HIV-related stigma (HSSS). Cronbach's alpha, first- and second-order confirmatory factor analysis (CFA), the Pearson coefficient and one-way ANOVA were used to evaluate reliability, construct validity and concurrent and known-group validity, respectively. Differences according to the socio-demographic and epidemiological profiles of participants were analyzed. RESULTS: First- and second-order CFAs confirmed a six-domain first-order structure of the Spanish version of WHOQOL-HIV-BREF and one second-order factor related to overall HRQoL with an acceptable fit to the data, although some minor changes would improve it. The six-domain structure showed an acceptable internal consistency (Cronbach's alpha ranged from .61 to .81). Significant moderate to large correlations between domains and overall HRQoL, adherence, psychological well-being and negative self-image were found. Significant differences were found according to participants' self-reported CD4+ cell count in several HRQoL facets and domains. Being female, heterosexual, having low socio-economic and educational statuses, having acquired HIV through an unsafe injection and living more years with HIV were related to poorer HRQoL. PLHIV older than 50 presented lower scores in 19 HRQoL facets. CONCLUSIONS: This study demonstrates that the Spanish version of the WHOQOL-HIV-BREF is a valid instrument. It also presents the most recent data about HRQoL in PLHIV in Spain with the largest sample to date.This study was funded by ViiV Healthcare (www.viivhealthcare.com). Study Number: SEISIDA 001/2016. ViiV Healthcare was involved in the study design and preparation of the manuscript, without influencing the data collection and analysis or the decision to publish. All listed authors meet the criteria for authorship set forth by the International Committee of Medical Journal Editors. All authors had full access to the data and are responsible for the veracity and completeness of the reported data.S

Imputation of the Date of HIV Seroconversion in a Cohort of Seroprevalent Subjects: Implications for Analysis of Late HIV Diagnosis

Objectives. Since subjects may have been diagnosed before cohort entry, analysis of late HIV diagnosis (LD) is usually restricted to the newly diagnosed. We estimate the magnitude and risk factors of LD in a cohort of seroprevalent individuals by imputing seroconversion dates. Methods. Multicenter cohort of HIV-positive subjects who were treatment naive at entry, in Spain, 2004–2008. Multiple-imputation techniques were used. Subjects with times to HIV diagnosis longer than 4.19 years were considered LD. Results. Median time to HIV diagnosis was 2.8 years in the whole cohort of 3,667 subjects. Factors significantly associated with LD were: male sex; Sub-Saharan African, Latin-American origin compared to Spaniards; and older age. In 2,928 newly diagnosed subjects, median time to diagnosis was 3.3 years, and LD was more common in injecting drug users. Conclusions. Estimates of the magnitude and risk factors of LD for the whole cohort differ from those obtained for new HIV diagnoses

HIV testing policies for migrants and ethnic minorities in EU/EFTA Member States.

In the context of an European Centre for Disease Prevention and Control (ECDC) research project, our objective was to describe current recommendations regarding HIV testing and counselling targeting migrants and ethnic minorities in the European Union/European Economic Area/European Free Trade Association (EU/EEA/EFTA) Member States. An on-line survey was conducted among 31 EU/EEA/EFTA Member States. The survey inquired on the existence of specific HIV testing and counselling recommendations or policies for migrants and/or ethnic minorities and the year of their publication. Additionally, we performed a review of national recommendations, guidelines or any other policy documents retrieved from an Internet search through the different countries' competent bodies. Twenty-nine (94%) country representatives responded the survey, and 28 documents from 27 countries were identified. National guidelines on HIV testing are heterogeneous and tailored, according to the epidemiological situation. Twenty-two countries identify migrants and four countries identify ethnic minorities as particularly vulnerable to HIV. Sixteen countries explicitly recommend offering an HIV test to migrants/ethnic minorities. Guidelines especially target people originating from HIV endemic countries, and benefits of HIV early detection are highlighted. HIV testing is not mandatory in any country, but some countries overtly facilitate this practice. Benefits of HIV testing in migrants and ethnic minorities, at both individual and community levels are recognized by many countries. In spite of this, not all countries identify the need to test these groups.European Centre for Disease Prevention and Control, Spanish Network of HIV/AIDS Research [RIS- RD06/0006] and the Biomedical Research Centre Network for Epidemiology and Public Health [CIBER de Epidemiología y Salud Pública].S

Overall and cause-specific mortality in HIV-positive subjects compared to the general population

Poster Session – Abstract P179INTRODUCTION: Emerging non-AIDS related causes of death have been observed in HIV-positive subjects in industrialized countries. We aimed to analyze overall and cause-specific excess of mortality of HIV-positive patients compared to the general population and to assess the effect of prognostic factors. MATERIAL AND METHODS: We used generalized linear models with Poisson error structure to estimate overall and cause-specific excess of mortality in HIV-positive patients from 2004 to 2012 in the cohort of the Spanish Network of HIV Research (CoRIS), compared to Spanish general population and to assess the impact of multiple risk factors. We investigated differences between short-term and long-term risk factors effects on excess of mortality. Multiple Imputation by Chained Equations was used to deal with missing data. RESULTS: In 9162 patients there were 363 deaths, 16.0% were non-AIDS malignancies, 10.5% liver and 0.3% cardiovascular related. Excess mortality was 1.20 deaths per 100 person years (py) for all-cause mortality, 0.16 for liver, 0.10 for non-AIDS malignancies and 0.03 for cardiovascular. Short-term (first-year follow-up) excess Hazard Ratio (eHR) for global mortality for baseline AIDS was 4.27 (95% CI 3.06-6.01) and 1.47 (95% CI 0.95-2.27) for HCV coinfection; long-term (subsequent follow-up) eHR for baseline AIDS was 0.88 (95% CI 0.58-1.35) and 4.48 (95% CI 2.71-7.42) for HCV coinfection. Lower CD4 count and higher viral load at entry, lower education, being male and over 50 years were predictors for overall excess mortality. Excess of liver mortality was higher in patients with CD4 counts at entry below 200 cells compared to those above 350 (eHR: 6.49, 95% CI 1.21-34.84) and in HCV-coinfected patients (eHR: 3.85, 95% CI 0.85- 17.37), although it was borderline significant. Patients over 50 years old (eHR: 5.55, 95%CI 2.4-12.85) and HCV coinfected (eHR: 5.81, 95% CI 2.6-13) showed a higher risk of non-AIDS malignancies mortality excess. Excess of cardiovascular mortality was related with HCV coinfection (eHR: 6.68, 95% CI 1.25-35.73). CONCLUSIONS: Our results show overall, liver, non-AIDS malignancies and cardiovascular excess of mortality associated with being HIV-positive, despite improvements in HIV disease management and antiretroviral therapies. Differential short-term and long-term effect of AIDS before entry and HCV coinfection was found for overall mortality.S