303 research outputs found
Redundancy in block coded modulations for channel equalization based on spatial and temporal diversity
Linear block codes in the complex field can be applied in spatial and/or temporal diversity receivers in order to develop high performance schemes for (almost-) blind equalization in mobile communications. The proposed technique uses the structure of the encoded transmitted information (with redundancy) to achieve equalization schemes based on a deterministic criterion. Simulations show that the proposed technique is more efficient than other schemes that follow similar equalizer structures. The result is an algorithm that provides the design of channel equalizers in low EbNo scenarios.Peer ReviewedPostprint (published version
Blind equalization based on spatial and temporal diversity in block coded modulations
Linear block codes can be applied in spatial and/or temporal diversity receivers in order to develop high performance schemes for blind equalization in mobile communications. The proposed technique uses the structure of the encoded transmitted information (with redundancy) to achieve equalization schemes based on a deterministic criterion. Simulations show that the proposed technique is more efficient than other schemes that follow similar equalizer structures. The result is an algorithm that provides the design of blind channel equalizers in low EbNo scenarios.Peer ReviewedPostprint (published version
Diversity in mobile communications for blind detection of block-coded modulations
Spatial, temporal, and frequency diversity structures are analyzed to address the blind equalization problem in the presence of time-variant frequency selective channels. The aim of the paper is to present equalization schemes useful in front of fast changing channel responses. The best solution is a deterministic blind criterion that allows direct channel equalization and symbol detection. The main contribution of this paper is to present deterministic blind equalization schemes in CDMA systems (frequency diversity) to reduce the impact of the time-variant frequency selective channel.Peer ReviewedPostprint (published version
Regulation of Ace2-dependent genes requires components of the PBF complex in schizosaccharomyces pombe
The division cycle of unicellular yeasts is completed with the activation of a cell separation program that results in the dissolution of the septum assembled during cytokinesis between the 2 daughter cells, allowing them to become independent entities. Expression of the eng1+ and agn1+ genes, encoding the hydrolytic enzymes responsible for septum degradation, is activated at the end of each cell cycle by the transcription factor Ace2. Periodic ace2+ expression is regulated by the transcriptional complex PBF (PCB Binding Factor), composed of the forkhead-like proteins Sep1 and Fkh2 and the MADS box-like protein Mbx1. In this report, we show that Ace2-dependent genes contain several combinations of motifs for Ace2 and PBF binding in their promoters. Thus, Ace2, Fkh2 and Sep1 were found to bind in vivo to the eng1+ promoter. Ace2 binding was coincident with maximum level of eng1+ expression, whereas Fkh2 binding was maximal when mRNA levels were low, supporting the notion that they play opposing roles. In addition, we found that the expression of eng1+ and agn1+ was differentially affected by mutations in PBF components. Interestingly, agn1+ was a major target of Mbx1, since its ectopic expression resulted in the suppression of Mbx1 deletion phenotypes. Our results reveal a complex regulation system through which the transcription factors Ace2, Fkh2, Sep1 and Mbx1 in combination control the expression of the genes involved in separation at the end of the cell division cycle
Septins localize to microtubules during nutritional limitation in Saccharomyces cerevisiae
<p>Abstract</p> <p>Background</p> <p>In <it>Saccharomyces cerevisiae</it>, nutrient limitation stimulates diploid cells to undergo DNA replication and meiosis, followed by the formation of four haploid spores. Septins are a family of proteins that assemble a ring structure at the mother-daughter neck during vegetative growth, where they control cytokinesis. In sporulating cells, the septin ring disassembles and septins relocalize to the prospore membrane.</p> <p>Results</p> <p>Here, we demonstrate that nutrient limitation triggers a change in the localization of at least two vegetative septins (Cdc10 and Cdc11) from the bud neck to the microtubules. The association of Cdc10 and Cdc11 with microtubules persists into meiosis, and they are found associated with the meiotic spindle until the end of meiosis II. In addition, the meiosis-specific septin Spr28 displays similar behavior, suggesting that this is a common feature of septins. Septin association to microtubules is a consequence of the nutrient limitation signal, since it is also observed when haploid cells are incubated in sporulation medium and when haploid or diploid cells are grown in medium containing non-fermentable carbon sources. Moreover, during meiosis II, when the nascent prospore membrane is formed, septins moved from the microtubules to this membrane. Proper organization of the septins on the membrane requires the sporulation-specific septins Spr3 and Spr28.</p> <p>Conclusion</p> <p>Nutrient limitation in <it>S. cerevisiae </it>triggers the sporulation process, but it also induces the disassembly of the septin bud neck ring and relocalization of the septin subunits to the nucleus. Septins remain associated with microtubules during the meiotic divisions and later, during spore morphogenesis, they are detected associated to the nascent prospore membranes surrounding each nuclear lobe. Septin association to microtubules also occurs during growth in non-fermentable carbon sources.</p
ADC Quantization Requirements
In this document, we analyze the impact of the quantization at the input of the demultiplexer. The required number of bits of the Analog-to-Digital-Converter (ADC) is obtained, along with the corresponding quantization losses.Preprin
A new approach for the validation of conceptual holonic constructions
The concepts of holon and holarchy were first applied
in the manufacturing world to develop Holonic Manufacturing
Systems. Since then, they have been used in many fields and have proved to be applicable concepts for developing applications in any business area. Resulting applications are based on conceptual holonic constructions. Like any model, a holarchy needs to be validated under real circumstances. Such validation assures the quality of the holarchy before it is implemented. In general, validation
research tends to target: 1) the specific types of holons handled in each proposal and/or the selected development paradigms; and 2) algorithm performance rather than architecture quality. This paper proposes and evaluates a methodology that focuses on the quality of the architecture. This methodology is able to validate any holonic architecture built to meet trade requirements.
Moreover, this is a general-purpose methodology. Therefore, the methodology would be valid for any domain and would not
be invalidated by holon types and/or implementation paradigms emerging, changing or falling into disuse. For this purpose, we consider holonic architectures as conceptual models, using the pure holon and holarchy concepts and passing up not only any specific implementation paradigm but also any set of specific holon
types
Regionalizing eco-toxicity characterization factors for copper soil emissions considering edaphic information for Northern Spain and Portuguese vineyards
The management of vineyards depends on the use of plant protection agents. Regardless of the numerous environmental impacts that these pesticides generate during their production, their dosage as pest control agents in vineyards causes an important toxic effect that must be monitored. Copper-based inorganic pesticides are the most widely used agents to control fungal diseases in humid wine-growing regions. It is, however, significant that the environmental analysis of their use through the Life Cycle Assessment (LCA) methodology does not provide detailed information on the potential toxicity of this type of pesticides. Hence, most studies report average values for copper characterization factors (CFs), excluding local soil characteristics. The objective of the study was the spatial characterization of the ecotoxicity factors of copper soil emissions as a function of the chemical characteristics of vineyard soils located in Portugal and Galicia (NW Spain). A multiple linear regression model was applied to calculate the comparative toxic potential. Subsequently, CFs for copper were calculated based on spatial differentiation considering the variable properties of the soil within each wine appellation. The CFs obtained for the area evaluated ranged from 141 to 5937 PAF·m3·day/kgCu emitted, for fibric histosols (HSf) and dystic cambisols (CMd), respectively. Moreover, the average values obtained for Galician and Portuguese soils were 1145 and 2274 PAF·m3·day/kgCu emitted, respectively. The results obtained illustrate the high variability of CF values as a function of the chemical characteristics of each type of soil. For example, Cu soil mobility was linked to organic carbon content and pH. Finally, to validate the representativeness of the calculated CFs, these were applied to the results of 12 literature life cycle inventories of grape production in the area evaluated, revealing that impact scores associated with Cu emissions can considerably vary when spatially-differentiated CFs are implemented.publishe
Renal dysfunction after orthotopic heart transplantation: incidence, natural history, and risk factors
[Abstract] Background. Renal dysfunction is a common complication after orthotopic heart transplantation (HT). The importance of factors other than exposure to immunosuppressive drugs is unclear. The purpose of this study was to determine the incidence and natural history of renal dysfunction following heart transplantation, and to evaluate a number of variables as risk factors for this condition.
Methods. We examined the creatinine levels at 1, 6, 12, 24, and 60 months in 262 consecutive heart transplant patients who survived at least 1 year. The potential risk factors included pre- and posttransplantation diabetes mellitus, arterial hypertension, and drugs used to control arterial hypertension.
Results. 17.2% of patients showed mild renal dysfunction (creatinine 1.5-2.5 mg/dL) and 1.9% moderate dysfunction (creatinine >2.5 mg/dL) at 1 month; 29.8% showed mild and 1.1% moderate dysfunction at 6 months; 33.2% showed mild and 1.9% moderate dysfunction at 1 year; 40% showed mild, 0.9% moderate and 0.4% severe dysfunction (requiring dialysis or renal transplantation) at 2 years; and 43.6% showed mild, 1.7% moderate and 0.9% severe dysfunction at 5 years. None of the conditions analyzed as possible risk factors showed a significant association with renal dysfunction except the use of diuretics.
Conclusion. The incidence of renal dysfunction after orthotopic heart transplantation was 33.6% within the first year after transplant and 44% within the first five years, although more than 95% of cases were mild. The incidence increased with time after transplantation. Renal dysfunction seems likely to be multifactorial in origin, but no individual risk factors were identified
Sedentarismo e inactividad física desde una perspectiva integral
[Abstract]: Objective: To characterize the prevalence of physical activity in the population aged ≥16 years integrating sedentarism and physical inactivity. Method: A cross-sectional study using data from the Galician Risk Behavior Data System (n = 12,928) was conducted. The population was classified into four categories: physically active (active and nonsedentary), active but sedentary (active and sedentary), lightly active (inactive and non-sedentary), and extremely sedentary (inactive and sedentary). Prevalences were calculated for each category and a multinomial logistic regression model was fitted. Results: 58.0% of the population was physically active and the remaining 42.0% presented some degree of sedentarism and/or physical inactivity. Men were more likely to be extremely sedentary. The risk of sedentarism decreased with age, and workers and/or students were prone to a higher risk of extreme sedentarism in comparison to those who reported other status. Extremely sendentary behaviors were also more common in people with higher educational levels, individuals living alone, residents of urban environments, and smokers. Conclusions: Joint evaluation of sedentarism and physical inactivity provides a more comprehensive and realistic picture of population behaviors related with physical activity. Since sedentarism is the most prevalent behavior, this study recommends that interventions be conducted at work and at academic environments.[Resumen]: Objetivo: Caracterizar la prevalencia de actividad física en la población ≥16 a˜ nos integrando sedentarismo e inactividad física. Método: Se realizó un estudio transversal con datos del Sistema de Datos de Conductas de Riesgo de Galicia (n = 12.928). La población se clasificó en cuatro categorías: físicamente activa (activa y no sedentaria), activa pero sedentaria (activa y sedentaria), poco activa (inactiva y no sedentaria) y extremadamente sedentaria (inactiva y sedentaria). Se calcularon las prevalencias para cada categoría y se ajustó un modelo de regresión logística multinomial. Resultados: El 58,0% de la población era físicamente activa y el 42,0% restante presentaba algún grado de sedentarismo o inactividad física. Los hombres eran más propensos a ser extremadamente sedentarios. El riesgo de sedentarismo disminuía con la edad, y los trabajadores o estudiantes eran propensos a un mayor riesgo de sedentarismo extremo en comparación con los que declaraban otra condición. Los comportamientos extremadamente sedentarios también fueron más frecuentes en personas con niveles educativos más altos, personas que vivían solas, residentes en entornos urbanos y fumadores. Conclusiones: La evaluación conjunta del sedentarismo y la inactividad física proporciona una imagen más completa y realista de los comportamientos de la población relacionados con la actividad física. Dado que el sedentarismo es el comportamiento más prevalente, este estudio recomienda que se realicen intervenciones en el ámbito laboral y académico.J. Rial-Vázquez has received a Margarita Salas study grant for the training of new doctors at A Coruña University (RSU.UDC.MS10)Universidade da Coruña; RSU.UDC.MS1
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