Estudio y diseño de elementos acústicos para proporcionar una acústica variable en una sala multifuncional

El objetivo de este proyecto es profundizar en el estudio y diseño de sistemas relacionados con el acondicionamiento acústico para una sala multifuncional. El proyecto se compone de dos partes. Una parte teórica y una parte práctica dónde se aplican los conceptos teóricos aprendidos. La primera parte, está dividida en capítulos en los que se habla de los siguientes temas: Acústica de salas. Para obtener una acústica adecuada en un recinto destinado a varias funciones, se debe contar con una serie de características que lo definan según su uso, por lo que es necesario conocer el tiempo de reverberación y otros parámetros subjetivos para poder caracterizar ese recinto. Materiales para el acondicionamiento acústico, donde se habla de los materiales absorbentes clasificándolos según las frecuencias a las que actúan y de los distintos tipos de difusores. Métodos para conseguir una acústica variable mediante la utilización de elementos físicos variables, citando casos reales de salas multifuncionales. La segunda parte, consiste en la realización de diseños de elementos de acústica variable para una posible utilización en salas polivalentes reales. La herramienta elegida a la hora de la elaboración de estos diseños es el AutoCad. Con esta herramienta se han realizado estos diseños representados en dos y tres dimensiones. ABSTRACT. The objective of this project is to deepen the study and design of systems related to multifunctional room acoustic conditioning. The project is composed of two parts. A theoretical part and a practical part where the learned theoretical concepts are applied. The first part is divided into chapters in which we talk about the following topics: Acoustics of rooms. To obtain proper acoustics in a room intended for various functions, you must have a number of characteristics that define it according to its use, so it is necessary to know the reverberation time and other subjective parameters to characterize the hall. Materials for acoustic conditioning, where we talk about the absorbent materials classified according to frequencies that those materials act and the different types of diffusers. Methods for obtain a variable acoustic by using variable physical elements, mentioning real cases of multi-purpose rooms. The second part deals with designs execution of variable acoustic elements for a possible use in a real multipurpose room. The chosen tool to develop these designs is the AutoCad. These designs have been made with this tool, represented in two and three dimensions.

Harvested populations are more variable only in more variable environments

Acknowledgments This work was funded by NERC grant NE/C510467/1 (T. G. Benton and S. B. Piertney) and a University of Leeds Faculty Postdoctoral Fellowship (T. C. Cameron). Data Accessibility The original time series and body size data from these experiments are available to download from DRYAD entry number http://dx.doi.org/10.5061/dryad.bq135.

Control of time-dependent biological processes by temporally patterned input

Temporal patterning of biological variables, in the form of oscillations and rhythms on many time scales, is ubiquitous. Altering the temporal pattern of an input variable greatly affects the output of many biological processes. We develop here a conceptual framework for a quantitative understanding of such pattern dependence, focusing particularly on nonlinear, saturable, time-dependent processes that abound in biophysics, biochemistry, and physiology. We show theoretically that pattern dependence is governed by the nonlinearity of the input–output transformation as well as its time constant. As a result, only patterns on certain time scales permit the expression of pattern dependence, and processes with different time constants can respond preferentially to different patterns. This has implications for temporal coding and decoding, and allows differential control of processes through pattern. We show how pattern dependence can be quantitatively predicted using only information from steady, unpatterned input. To apply our ideas, we analyze, in an experimental example, how muscle contraction depends on the pattern of motorneuron firing.

Variable efficacy of repeated annual influenza vaccination

Conclusions have differed in studies that have compared vaccine efficacy in groups receiving influenza vaccine for the first time to efficacy in groups vaccinated more than once. For example, the Hoskins study [Hoskins, T. W., Davis, J. R., Smith, A. J., Miller, C. L. & Allchin, A. (1979) Lancet i, 33–35] concluded that repeat vaccination was not protective in the long term, whereas the Keitel study [Keitel, W. A., Cate, T. R., Couch, R. B., Huggins, L. L. & Hess, K. R. (1997) Vaccine 15, 1114–1122] concluded that repeat vaccination provided continual protection. We propose an explanation, the antigenic distance hypothesis, and test it by analyzing seven influenza outbreaks that occurred during the Hoskins and Keitel studies. The hypothesis is that variation in repeat vaccine efficacy is due to differences in antigenic distances among vaccine strains and between the vaccine strains and the epidemic strain in each outbreak. To test the hypothesis, antigenic distances were calculated from historical hemagglutination inhibition assay tables, and a computer model of the immune response was used to predict the vaccine efficacy of individuals given different vaccinations. The model accurately predicted the observed vaccine efficacies in repeat vaccinees relative to the efficacy in first-time vaccinees (correlation 0.87). Thus, the antigenic distance hypothesis offers a parsimonious explanation of the differences between and within the Hoskins and Keitel studies. These results have implications for the selection of influenza vaccine strains, and also for vaccination strategies for other antigenically variable pathogens that might require repeated vaccination.

Visual constraints in foraging bumblebees: Flower size and color affect search time and flight behavior

In optimal foraging theory, search time is a key variable defining the value of a prey type. But the sensory-perceptual processes that constrain the search for food have rarely been considered. Here we evaluate the flight behavior of bumblebees (Bombus terrestris) searching for artificial flowers of various sizes and colors. When flowers were large, search times correlated well with the color contrast of the targets with their green foliage-type background, as predicted by a model of color opponent coding using inputs from the bees' UV, blue, and green receptors. Targets that made poor color contrast with their backdrop, such as white, UV-reflecting ones, or red flowers, took longest to detect, even though brightness contrast with the background was pronounced. When searching for small targets, bees changed their strategy in several ways. They flew significantly slower and closer to the ground, so increasing the minimum detectable area subtended by an object on the ground. In addition, they used a different neuronal channel for flower detection. Instead of color contrast, they used only the green receptor signal for detection. We relate these findings to temporal and spatial limitations of different neuronal channels involved in stimulus detection and recognition. Thus, foraging speed may not be limited only by factors such as prey density, flight energetics, and scramble competition. Our results show that understanding the behavioral ecology of foraging can substantially gain from knowledge about mechanisms of visual information processing.

A general additive distance with time-reversibility and rate variation among nucleotide sites.

As additivity is a very useful property for a distance measure, a general additive distance is proposed under the stationary time-reversible (SR) model of nucleotide substitution or, more generally, under the stationary, time-reversible, and rate variable (SRV) model, which allows rate variation among nucleotide sites. A method for estimating the mean distance and the sampling variance is developed. In addition, a method is developed for estimating the variance-covariance matrix of distances, which is useful for the statistical test of phylogenies and molecular clocks. Computer simulation shows (i) if the sequences are longer than, say, 1000 bp, the SR method is preferable to simpler methods; (ii) the SR method is robust against deviations from time-reversibility; (iii) when the rate varies among sites, the SRV method is much better than the SR method because the distance is seriously underestimated by the SR method; and (iv) our method for estimating the sampling variance is accurate for sequences longer than 500 bp. Finally, a test is constructed for testing whether DNA evolution follows a general Markovian model.

Stars and brown dwarfs in the σ Orionis cluster (Research Note) III. OSIRIS/GTC low-resolution spectroscopy of variable sources

Context. Although many studies have been performed so far, there are still dozens of low-mass stars and brown dwarfs in the young σ Orionis open cluster without detailed spectroscopic characterisation. Aims. We look for unknown strong accretors and disc hosts that were undetected in previous surveys. Methods. We collected low-resolution spectroscopy (R ~ 700) of ten low-mass stars and brown dwarfs in σ Orionis with OSIRIS at the Gran Telescopio Canarias under very poor weather conditions. These objects display variability in the optical, infrared, Hα, and/or X-rays on time scales of hours to years. We complemented our spectra with optical and near-/mid-infrared photometry. Results. For seven targets, we detected lithium in absorption, identified Hα, the calcium doublet, and forbidden lines in emission, and/or determined spectral types for the first time. We characterise in detail a faint, T Tauri-like brown dwarf with an 18 h-period variability in the optical and a large Hα equivalent width of –125  ±  15 Å, as well as two M1-type, X-ray-flaring, low-mass stars, one with a warm disc and forbidden emission lines, the other with a previously unknown cold disc with a large inner hole. Conclusions. New unrevealed strong accretors and disc hosts, even below the substellar limit, await discovery among the list of known σ Orionis stars and brown dwarfs that are variable in the optical and have no detailed spectroscopic characterisation yet.

Modeling construction time in Spanish building projects

The literature states that project duration is affected by various scope factors. Using 168 building projects carried out in Spain, this paper uses the multiple regression analysis to develop a forecast model that allows estimating project duration of new builds. The proposed model uses project type, gross floor area (GFA), the cost/GFA relationship and number of floors as predictor variables. The research identified the logarithmic form of construction speed as the most appropriate response variable. GFA has greater influence than cost on project duration but both factors are necessary to achieve a forecast model with the highest accuracy. We developed an analysis to verify the stability of forecasted values and showed how a model with high values of fit and accuracy may display an anomalous behavior in the forecasted values. The sensitivity of the proposed forecast model was also analyzed versus the variability of construction costs.

Difference schemes for time-dependent heat conduction models with delay

Different non-Fourier models of heat conduction, that incorporate time lags in the heat flux and/or the temperature gradient, have been increasingly considered in the last years to model microscale heat transfer problems in engineering. Numerical schemes to obtain approximate solutions of constant coefficients lagging models of heat conduction have already been proposed. In this work, an explicit finite difference scheme for a model with coefficients variable in time is developed, and their properties of convergence and stability are studied. Numerical computations showing examples of applications of the scheme are presented.

The outburst decay of the low magnetic field magnetar SWIFT J1822.3−1606: phase-resolved analysis and evidence for a variable cyclotron feature

We study the timing and spectral properties of the low-magnetic field, transient magnetar SWIFT J1822.3−1606 as it approached quiescence. We coherently phase-connect the observations over a time-span of ∼500 d since the discovery of SWIFT J1822.3−1606 following the Swift-Burst Alert Telescope (BAT) trigger on 2011 July 14, and carried out a detailed pulse phase spectroscopy along the outburst decay. We follow the spectral evolution of different pulse phase intervals and find a phase and energy-variable spectral feature, which we interpret as proton cyclotron resonant scattering of soft photon from currents circulating in a strong (≳1014 G) small-scale component of the magnetic field near the neutron star surface, superimposed to the much weaker (∼3 × 1013 G) magnetic field. We discuss also the implications of the pulse-resolved spectral analysis for the emission regions on the surface of the cooling magnetar.

Age determination of sediments of Site LO09-14 (Table 1)

A composite record (LO09-14) of three sediment cores from the subpolar North Atlantic (Reykjanes Ridge) was investigated in order to assess surface ocean variability during the last 11 kyr. The core site is today partly under the influence of the Irminger Current (IC), a branch of the North Atlantic Drift continuing northwestward around Iceland. However, it is also proximal to the Sub-Arctic Front (SAF) that may cause extra dynamic hydrographic conditions. We used statistical methods applied to the fossil assemblages of diatoms to reconstruct quantitative sea surface temperatures (SSTs). Our investigations give evidence for different regional signatures of Holocene surface oceanographic changes in the North Atlantic. Core LO09-14 reveal relatively low and highly variable SSTs during the early Holocene, indicating a weak IC and increased advection of subpolar water over the site. A mid-Holocene thermal optimum with a strong IC occurs from 7.5 to 5 kyr and is followed by cooler and more stable late Holocene surface conditions. Several intervals throughout the Holocene are dominated by the diatom species Rhizosolenia borealis, which we suggest indicates proximity to a strongly defined convergence front, most likely the SAF. Several coolings, reflecting southeastward advection of cold and ice-bearing waters, occur at 10.4, 9.8, 8.3, 7.9, 6.4, 4.7, 4.3 and 2.8 kyr. The cooling events recorded in the LO09-14 SSTs correlate well with both other surface records from the area and the NADW reductions observed at ODP Site 980 indicating a surface-deepwater linkage through the Holocene.

Geochemistry of sediments of stage 5 of the Nordic seas

Stable isotope, foraminifera and ice rafted detritus (IRD) records covering the last interglacial (the Eemian) from 7 sediment cores in a transect from the Norwegian to the Greenland Sea are presented. The percentages of Neogloboquadrina pachyderma (s.) and Globigerina quinqueloba, foraminiferal content, and to some extent planktonic stable isotope records, demonstrate marked, regional changes in surface water conditions. Importantly, the variability in the abundances of subpolar foraminifera and foraminiferal content are not coherent, implying that these two types of proxies fluctuated independently of each other and most likely reflect changes in sea surface temperature and surface water carbonate productivity, respectively. Paleoceanographic reconstructions demonstrate significant movements of the oceanographic fronts. At the warmest periods, the Arctic front was located far west of the present-day location, at least within the Iceland Sea region. At 126-125 ka, this was most probably due to a stronger or more westerly located Norwegian current. Within the later warm intervals, higher heat flux to the western part of the basin reflects a combination of a stronger Irminger current and/or a weaker east Greenland current. During the main cold spell at ~124 ka, a diffuse Arctic front had a more southeasterly location than today, and intrusion of Atlantic surface waters was probably limited to a narrow corridor in the Eastern Norwegian Sea. A general correspondence between minima in sea surface temperatures and light benthic delta18O may indicate enhanced influx of freshwater to the basin within the cold events. At least in the Norwegian Sea, we find some evidence that the changes in surface water conditions are associated with changes in deep water ventilation. The majority of the fluctuations may be related to occasional breakdown or reduction of the thermohaline circulation within the Nordic seas. In the earliest Eemian, this could result from meltwater forcing. During the remaining part of the last interglacial the fine balance between temperature and salinity, which the deep water formation is depending on, may have been disturbed by periodic increases in fresh water supply or variable influx of warm Atlantic surface waters.

Valve concentration of Ethmodiscus sp. and carbon in sediment core GeoB3801-6

Within generally calcareous sediment sequences, layers of variable thickness of the giant diatom Ethmodiscus were found in five cores recovered in the Subtropical South Atlantic between 23° and 33°S from both sides of the Mid-Atlantic Ridge. Two types of oozes occur: (almost) monospecific layers of Ethmodiscus and layers dominated by Ethmodiscus, with several accompanying tropical/subtropical, oligotrophic-water diatoms. The two thickest Ethmodiscus layers occur in GeoB3801-6 around 29°S, and accumulated during late MIS 14 and MIS 12, respectively. Downcore concentrations of Ethmodiscus valves range between 3.4 10 4 and 2.3 10 7 valves g -1. We discuss the ooze formation in the context of migration of frontal systems and changes in the thermohaline circulation. The occurrence of Ethmodiscus oozes in sediments underlying the present-day pelagic, low-nutrient waters is associated with a terminal event of the Mid-Pleistocene Transition at around 530 ka, when the ocean circulation rearranged after a period of reduced NADW production.

Nd isotope ratios of surface sediments from the Pacific Ocean (Table 2)

The neodymium isotopic composition of the silicate fraction of Holocene pelagic sediments from the North Pacific define two provinces: a central North Pacific province characterized by unradiogenic and remarkably homogeneous end (-10.2 +/- 0.5) and a narrow circum-Pacific marginal province characterized by more radiogenic and variable end (-4.2 +/- 3.8). The silicate fraction in the central North Pacific is exclusively eolian; based on prevailing wind patterns, meteorological data, and neodymium isotopic data, the only significant sediment source is Chinese loess. Leaching experiments on Chinese loess confirm that leachable Nd is isotopically indistinguishable from bulk and residual silicate Nd. Silicates in the circum-North Pacific marginal province comprise eolian loess, volcanic ash, and hemipelagic sediments derived from volcanic arcs. A compilation of Pacific seawater and Mn nodule epsilon-Nd data shows no clear spatial variation except for a general decrease from surface to deep waters from -3 to -4 and slightly lower epsilon-Nd in bottom waters along the western North Pacific due to the incursion of Antarctic Bottom Water. The relative homogeneity of bottom water epsilon-Nd, which contrasts sharply with the distinctive variation in sediment epsilon-Nd, plus the large difference between the average end of bottom waters and the central North Pacific eolian silicates (-4 vs. -10), suggests that any contribution of REE to seawater from eolian materials is insignificant. Furthermore, leaching of REE from eolian particles as they sink though the water column must be insignificant because Nd in shallow waters is more radiogenic than Nd in deeper waters. That there is no contrast in the Nd isotopic composition of bottom waters that overlie the central and marginal sediment provinces suggests that the ash and hemipelagic sediments derived from Pacific rim volcanic arcs also contribute minimal REE to seawater. The elimination of eolian, ash, and hemipelagic sediments leaves only near-shore riverine particulates as a possibly significant particulate source of REE to seawater.