1,463 research outputs found
Efficient memory management in video on demand servers
In this article we present, analyse and evaluate a new memory management technique for video-on-demand servers. Our proposal,
Memory Reservation Per Storage Device (MRPSD), relies on the allocation of a fixed, small number of memory buffers per storage device.
Selecting adequate scheduling algorithms, information storage strategies and admission control mechanisms, we demonstrate that MRPSD is suited for the deterministic service of variable bit rate streams to intolerant clients. MRPSD allows large memory savings compared to traditional memory management techniques, based on the allocation of a certain amount of memory per client served, without a significant performance penaltyPublicad
Thermal Perception in Mild Climate: Adaptive Thermal Models for Schools
A comprehensive assessment of indoor environmental conditions is performed on a
representative sample of classrooms in schools across southern Spain (Mediterranean climate) to
evaluate the thermal comfort level, thermal perception and preference, and the relationship with
HVAC systems, with a comparison of seasons and personal clothing. Almost fifty classrooms were
studied and around one thousand pool-surveys distributed among their occupants, aged 12 to 17.
These measurements were performed during spring, autumn, and winter, considered the most
representative periods of use for schools. A new proposed protocol has been developed for the
collection and subsequent analysis of data, applying thermal comfort indicators and using the most
frequent predictive models, rational (RTC) and adaptive (ATC), for comparison. Cooling is not
provided in any of the rooms and natural ventilation is found in most of the spaces during midseasons.
Despite the existence of a general heating service in almost all classrooms in the cold period, the use
of mechanical ventilation is limited. Heating did not usually provide standard set-point temperatures.
However, this did not lead to widespread complaints, as occupants perceive the thermal environment
as neutral—varying greatly between users—and show a preference for slightly colder environments.
Comparison of these thermal comfort votes and the thermal comfort indicators used showed a better
fit of thermal preference over thermal sensation and more reliable results when using regional ATC
indicators than the ASHRAE adaptive model. This highlights the significance of inhabitants’ actual
thermal perception. These findings provide useful insight for a more accurate design of this type of
building, as well as a suitable tool for the improvement of existing spaces, improving the conditions
for both comfort and wellbeing in these spaces, as well as providing a better fit of energy use for
actual comfort conditions
Robust symmetric multiplication for programmable analog VLSI array processing
This paper presents an electrically programmable analog multiplier. The circuit performs the multiplication between an input variable and an electrically selectable scaling factor. The multiplier is divided in several blocks: a linearized transconductor, binary weighted current mirrors and a differential to single-ended current adder. This paper shows the advantages introduced using a linearized OTA-based multiplier. The circuit presented renders higher linearity and symmetry in the output current than a previously reported single-transistor multiplier. Its inclusion in an array processor based on CNN allows for a more accurate implementation of the processing model and a more robust weight distribution scheme than those found in previous designs.Office of Naval Research (USA) N-00014- 02-1-0884Ministerio de Ciencia y Tecnología TIC2003-09817-C02-0
A Focal-Plane Image Processor for Low Power Adaptive Capture and Analysis of the Visual Stimulus
Portable applications of artificial vision are limited by the fact that conventional processing schemes fail to meet the specifications under a tight power budget. A bio-inspired approach, based in the goal-directed organization of sensory organs found in nature, has been employed to implement a focal-plane image processor for low power vision applications. The prototype contains a multi-layered CNN structure concurrent with 32times32 photosensors with locally programmable integration time for adaptive image capture with on-chip local and global adaptation mechanisms. A more robust and linear multiplier block has been employed to reduce irregular analog wave propagation ought to asymmetric synapses. The predicted computing power per power consumption, 142MOPS/mW, is orders of magnitude above what rendered by conventional architectures
Retribución en farmacia comunitaria. Visión en otros países
INTRODUCCIÓN La retribución, que según la RAE, es la recompensa o pago por algo, constituye un factor de máxima relevancia en la determinación de la eficiencia de una actividad. Como en cualquier actividad profesional, en la farmacia comunitaria es un determinante de la consecución de los objetivos de la misma. En base a ello, el objetivo del presente estudio es analizar la estructura de la retribución de la dispensación en la farmacia comunitaria en España, comparándola con la de otros países representativos a nivel internacional.MÉTODOS Se realizó una búsqueda en internet de las disposiciones oficiales sobre los diferentes sistemas retributivos actualmente en vigor para cada país seleccionado. Se seleccionaron las estructuras de remuneración de la farmacia comunitaria en diversos países de Europa (Alemania, Bélgica, Francia, Gran Bretaña, Holanda, Irlanda y Suiza), América (Canadá y Estados Unidos) y Australia (Australia).RESULTADOS En España, la retribución de la dispensación en la farmacia comunitaria se basa exclusivamente en un porcentaje sobre el precio de venta del medicamento. En los demás países analizados, dicha retribución ha ido evolucionando hacia el pago de honorarios por las intervenciones farmacéuticas desarrolladas, desligándose así del precio del medicamento y asimilando el trabajo del farmacéutico más a una actividad profesional que mercantil.CONCLUSIONES El sistema retributivo de la dispensación de la farmacia comunitaria en España debería evolucionar, al igual que ocurre en el resto de los países analizados, hacia un sistema basado en un honorario profesional por las actividades profesionales realizadas, desterrando definitivamente el actual sistema retributivo basado en un margen sobre el precio de venta del medicamento
Mediating Effects of Diagnostic Route on the Comorbidity Gap in Survival of Patients with Diffuse Large B-Cell or Follicular Lymphoma in England
Background: Socioeconomic inequalities in survival from non-Hodgkin lymphoma persist.
Comorbidities are more prevalent amongst those in more deprived areas and are associated with
diagnostic delay (emergency diagnostic route), which is also associated with poorer survival probability.
We aimed to describe the effect of comorbidity on the probability of death mediated by diagnostic
route (emergency vs. elective route) amongst patients with diffuse large B-cell (DLBCL) or follicular
lymphoma (FL). Methods: We linked the English population-based cancer registry and hospital
admission records (2005–2013) of patients aged 45–99 years. We decomposed the effect of comorbidity
on survival into an indirect effect acting through diagnostic route and a direct effect not mediated by
diagnostic route. Furthermore, we estimated the proportion of the comorbidity effect on survival
mediated by diagnostic route. Results: For both DLBCL (n = 27,379) and FL (n = 14,043), those with
any comorbidity, or living in more deprived areas, were more likely to experience diagnostic delay
and poorer survival. The indirect effect of comorbidity on mortality through diagnostic route was
highest at 12 months since diagnosis (DLBCL: Odds Ratio 1.10 [95% CI 1.07–1.13], FL: OR 1.09 [95%
CI 1.04–1.14]). Within the first 12 months since diagnosis, emergency diagnostic route accounted for
24% (95% CI 17.5–29.5) and 16% (95% CI 6.0–25.6) of the comorbidity effect on mortality, for DLBCL
and FL, respectively. Conclusion: Efforts to reduce diagnostic delay (emergency diagnosis) amongst
patients with comorbidity would reduce inequalities in DLBCL and FL survival by 24% and 16%,
respectively. Further public health programs and interventions are needed to reduce diagnostic delay
amongst lymphoma patients with comorbidities.Cancer Research UK C7923/A1852
CO2 Concentration and Occupants’ Symptoms in Naturally Ventilated Schools in Mediterranean Climate
A large part of the school building stock in Andalusia lacks ventilation facilities, so that
the air renewal of the classrooms is achieved through the building envelope (air infiltration) or the
opening of windows. This research analyses the airtightness of the classrooms in Andalusia and the
evolution of CO2 concentration during school hours through in situ monitoring. Pressurization and
depressurization tests were performed in 42 classrooms and CO2 concentration was measured in
two di erent periods, winter and midseason, to study the impact of the di erent levels of aperture
of windows. About 917 students (11–17 years of age) were surveyed on symptoms and e ects on
their health. The mean n50 values are about 7 h-1, whereas the average CO2 concentration values
are about 1878 ppm, with 42% of the case studies displaying concentrations above 2000 ppm with
windows closed
Review of ADCs for imaging
The aim of this article is to guide image sensors designers to optimize the analog-to-digital conversion of pixel outputs. The most common ADCs topologies for image sensors are presented and discussed. The ADCs specific requirements for these sensors are analyzed and quantified. Finally, we present relevant recent contributions of specific ADCs for image sensors and we compare them using a novel FOM. © (2014) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use onlyPeer reviewe
Steel passive state stability in activated fly ash mortars
[EN] The present study explores the behaviour of structural steel embedded in Portland cement (OPC) mortars and
NaOH- and NaOH+waterglass-activated fly ash, in the presence and absence of 2% Cl- (CaCl2). Variations were determined in the corrosion potential (Ecorr),
linear polarization resistance (Rp) and corrosion current density (icorr) under different environmental conditions
(90 days at 95% relative humidity (RH), 30 days at ≈30 % RH, 760 days at ≈ 95% RH). In the absence of Cl-, fly ash mortars were able to passivate steel reinforcement, although the stability of the passive
state in changing environmental conditions was found to depend heavily on the activating solution used. Steel
corrosion in the presence of 2% Cl- was observed to be similar to the corrosion reported for the material in OPC
mortars.[ES] En el presente trabajo se estudia el comportamiento del acero estructural embebido en morteros de cemento Pórtland (OPC) y de cenizas volantes activadas
con NaOH y una mezcla de NaOH y waterglass, en ausencia y en presencia de un 2% de Cl- (CaCl2). Se determinó la evolución del potencial de corrosión (Ecorr), la resistencia de polarización lineal (Rp) y la
intensidad de corrosión (icorr), variando las condiciones ambientales (90 días al 95% de humedad relativa(HR) -30 días a ≈ 30% HR- 760 días a ≈ 95% HR).En ausencia de Cl- los morteros de cenizas volantes activadas
pueden pasivar los refuerzos de acero, si bien la estabilidad del estado pasivo ante cambios en las condiciones ambientales parece mostrar una fuerte dependencia de la solución activadora empleada. Enpresencia de un 2% de Cl- los aceros se corroen mostrando
en comportamiento similar al observado en
morteros en base OPC.Peer reviewe
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