946 resultados para time-of-use
Resumo:
The purpose of this study was to evaluate summer and fall residency and habitat selection by gray whales, Eschrichtius robustus, together with the biomass of benthic amphipod prey on the coastal feeding grounds along the Chukotka Peninsula. Thirteen gray whales were instrumented with satellite transmitters in September 2006 near the Chukotka Peninsula, Russia. Nine transmitters provided positions from whales for up to 81 days. The whales travelled within 5 km of the Chukotka coast for most of the period they were tracked with only occasional movements offshore. The average daily travel speeds were 23 km/day (range 9-53 km/day). Four of the whales had daily average travel speeds <1 km/day suggesting strong fidelity to the study area. The area containing 95% of the locations for individual whales during biweekly periods was on average 13,027 km**2 (range 7,097-15,896 km**2). More than 65% of all locations were in water <30 m, and between 45 and 70% of biweekly kernel home ranges were located in depths between 31 and 50 m. Benthic density of amphipods within the Bering Strait at depths <50 m was on average ~54 g wet wt/m**2 in 2006. It is likely that the abundant benthic biomass is more than sufficient forage to support the current gray whale population. The use of satellite telemetry in this study quantifies space use and movement patterns of gray whales along the Chukotka coast and identifies key feeding areas.
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Although there are numerous accurate measuring methods to determine soil moisture content in a spot, until very recently there were no precise in situ and in real time methods that were able to measure soil moisture content along a line. By means of the Distributed Fiber Optic Temperature Measurement method or DFOT, the temperature in 0.12 m intervals and long distances (up to 10,000 m) with a high time frequency and an accuracy of +0.2º C is determined. The principle of temperature measurement along a fiber optic cable is based on the thermal sensitivity of the relative intensities of backscattered photons that arise from collisions with electrons in the core of the glass fiber. A laser pulse, generated by the DTS unit, traversing a fiber optic cable will result in backscatter at two frequencies. The DTS quantifies the intensity of these backscattered photons and elapsed time between the pulse and the observed returned light. The intensity of one of the frequencies is strongly dependent on the temperature at the point where the scattering process occurred. The computed temperature is attributed to the position along the cable from which the light was reflected, computed from the time of travel for the light.
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This study investigates the effect of price and travel time fairness and spatial equity in transit provision on the perceived transit service quality, willingness to pay, and habitual frequency of use. Based on the theory of planned behavior, we developed a web-based questionnaire for revealed preferences data collection. The survey was administered among young people in Copenhagen and Lisbon to explore the transit perceptions and use under different economic and transit provision conditions. The survey yielded 499 questionnaires, analyzed by means of structural equation models. Results show that higher perceived fairness relates positively to higher perceived quality of transit service and higher perceived ease of paying for transit use. Higher perceived spatial equity in service provision is associated with higher perceived service quality. Higher perceived service quality relates to higher perceived ease of payment, which links to higher frequency of transit use.
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Interaction of light-activated rhodopsin with transducin (T) is the first event in visual signal transduction. We use covalent crosslinking approaches to map the contact sites in interaction between the two proteins. Here we use a photoactivatable reagent, N-[(2-pyridyldithio)-ethyl], 4-azido salicylamide. The reagent is attached to the SH group of cytoplasmic monocysteine rhodopsin mutants by a disulfide-exchange reaction with the pyridylthio group, and the derivatized rhodopsin then is complexed with T by illumination at λ >495 nm. Subsequent irradiation of the complex at λ310 nm generates covalent crosslinks between the two proteins. Crosslinking was demonstrated between T and a number of single cysteine rhodopsin mutants. However, sites of crosslinks were investigated in detail only between T and the rhodopsin mutant S240C (cytoplasmic loop V-VI). Crosslinking occurred predominantly with Tα. For identification of the sites of crosslinks in Tα, the strategy used involved: (i) derivatization of all of the free cysteines in the crosslinked proteins with N-ethylmaleimide; (ii) reduction of the disulfide bond linking the two proteins and isolation of all of the Tα species carrying the crosslinked moiety with a free SH group; (iii) adduct formation of the latter with the N-maleimide moiety of the reagent, maleimido-butyryl-biocytin, containing a biotinyl group; (iv) trypsin degradation of the resulting Tα derivatives and isolation of Tα peptides carrying maleimido-butyryl-biocytin by avidin-agarose chromatography; and (v) identification of the isolated peptides by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. We found that crosslinking occurred mainly to two C-terminal peptides in Tα containing the amino acid sequences 310–313 and 342–345.
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It has become clear that many organisms possess the ability to regulate their mutation rate in response to environmental conditions. So the question of finding an optimal mutation rate must be replaced by that of finding an optimal mutation schedule. We show that this task cannot be accomplished with standard population-dynamic models. We then develop a "hybrid" model for populations experiencing time-dependent mutation that treats population growth as deterministic but the time of first appearance of new variants as stochastic. We show that the hybrid model agrees well with a Monte Carlo simulation. From this model, we derive a deterministic approximation, a "threshold" model, that is similar to standard population dynamic models but differs in the initial rate of generation of new mutants. We use these techniques to model antibody affinity maturation by somatic hypermutation. We had previously shown that the optimal mutation schedule for the deterministic threshold model is phasic, with periods of mutation between intervals of mutation-free growth. To establish the validity of this schedule, we now show that the phasic schedule that optimizes the deterministic threshold model significantly improves upon the best constant-rate schedule for the hybrid and Monte Carlo models.
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Many of the educational structures in public education today have their roots in the educational reforms of the industrial and Cold War eras. These educational structures served the United States well in a time of industrialization and two-state global superpowers. However, society has rapidly become more interconnected and globalized. K-12 education has not required that students develop the new skills and habits of mind needed for success in the twenty-first century. This study proposes three curricular and instructional changes to help students meet the needs of a global society in Adams Twelve Five-Star Schools located in Thornton, Colorado. These curricular and instructional reforms, while intended to address globalization, will also help the district stay competitive among local districts.
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The Lomb periodogram has been traditionally a tool that allows us to elucidate if a frequency turns out to be important for explaining the behaviour of a given time series. Many linear and nonlinear reiterative harmonic processes that are used for studying the spectral content of a time series take into account this periodogram in order to avoid including spurious frequencies in their models due to the leakage problem of energy from one frequency to others. However, the estimation of the periodogram requires long computation time that makes the harmonic analysis slower when we deal with certain time series. Here we propose an algorithm that accelerates the extraction of the most remarkable frequencies from the periodogram, avoiding its whole estimation of the harmonic process at each iteration. This algorithm allows the user to perform a specific analysis of a given scalar time series. As a result, we obtain a functional model made of (1) a trend component, (2) a linear combination of Fourier terms, and (3) the so-called mixed secular terms by reducing the computation time of the estimation of the periodogram.
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Anion clay hydrotalcite sorbents were prepared to investigate their adsorption capabilities in the removal of coloured organic substances from various aqueous systems. Anion clay hydrotalcite was found to be particularly effective at removing negatively charged species. Its excellent uptake levels of anionic species can be accounted for by its high surface area and anion exchange ability. That is, coloured substances can be adsorbed on the surface or enter the interlayer region of the clay by anion exchange. In the adsorption of Acid Blue 29 on the anion clay hydrotalcite, an equilibrium time of 1 h with dye removal exceeding 99% was obtained. The hydrotalcite was found to have an adsorption capacity marginally below that of commercial activated carbon. It should be noted that the spent sorbents can be regenerated easily by heating at 723 K to remove all adsorbed organics. The reused sorbents displayed greater adsorption capabilities than the newly prepared hydrotalcite. Hence, the anion clay hydrotalcite is easily recoverable and reusable such that it is a promising sorbent for environmental and purification purposes. (C) 2002 Elsevier Science B.V. All rights reserved.
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Although the use of alternative therapies is highly prevalent amongst men with prostate cancer, research about the predictors of such use is limited. The current study aimed to describe prospectively the use of alternative therapies by men diagnosed with localized prostate cancer and identify predictors of alternative therapy use. In all, 111 men newly diagnosed with localized prostate cancer (93% response) were recruited to the study prior to treatment. Men's use of alternative therapies and psychological variables including: psychological distress, orientation to health care, decisional conflict, and health locus of control, were assessed at three time points-(1) before treatment; (2) 2 months after completion of treatment; and (3) 12 months after completion of treatment. Demographic information was also obtained. The percentage of men using alternative therapies was 25, 17 and 14% before treatment, 2 and 12 months after treatment, respectively. In general, the most commonly used therapies were dietary changes, vitamins and herbal and nutrient remedies. Alternative therapy use was not related to final treatment choices. Before treatment, men who used alternative therapies were more uncertain about prostate cancer compared to men who were not using these therapies. Men who were using alternative therapies 12 months after treatment were less psychologically distressed that men who were not using these therapies. Health locus of control and orientation to health care were not found to be related to men's use of alternative therapies. In conclusion, men's use of alternative therapies after localized prostate cancer varied across time in terms of the incidence of use, the types of therapies used, and the psychological correlates of therapy use. Informational support that targets uncertainty about prostate cancer may assist men at diagnosis who are considering alternative therapy use. The potential for alternative therapies to have a supportive function in patient care requires further investigation. (C) 2003 Elsevier Ireland Ltd. All rights reserved.
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1. Many species of delphinids co-occur in space and time. However, little is known of their ecological interactions and the underlying mechanisms that mediate their coexistence. 2. Snubfin Orcaella heinsohni, and Indo-Pacific humpback dolphins Sousa chinensis, live in sympatry throughout most of their range in Australian waters. I conducted boat-based surveys in Cleveland Bay, north-east Queensland, to collect data on the space and habitat use of both species. Using Geographic Information Systems, kernel methods and Euclidean distances I investigated interspecific differences in their space use patterns, behaviour and habitat preferences. 3. Core areas of use (50% kernel range) for both species were located close to river mouths and modified habitat such as dredged channels and breakwaters close to the Port of Townsville. Foraging and travelling activities were the dominant behavioural activities of snubfin and humpback dolphins within and outside their core areas. 4. Their representative ranges (95% kernel range) overlapped considerably, with shared areas showing strong concordance in the space use by both species. Nevertheless, snubfin dolphins preferred slightly shallower (1-2 m) waters than humpback dolphins (2-5 m). Additionally, shallow areas with seagrass ranked high in the habitat preferences of snubfin dolphins, whereas humpback dolphins favoured dredged channels. 5. Slight differences in habitat preferences appear to be one of the principal factors maintaining the coexistence of snubfin and humpback dolphins. I suggest diet partitioning and interspecific aggression as the major forces determining habitat selection in these sympatric species.
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Drought is a major constraint for rice production in the rainfed lowlands in Southeast Asia and Eastern India. The breeding programs for tainted lowland rice in these regions focus on adaptation to a range of drought conditions. However, a method of selection of drought tolerant genotypes has not been established and is considered to be one of the constraints faced by rice breeders. Drought response index (DRI) is based on grain yield adjusted for variation in potential yield and flowering date, and has been used recently, but its consistency among drought environments and hence its usefulness is not certain. In order to establish a selection method and subsequently to identify donor parents for drought resistance breeding, a series of experiments with 15 contrasting genotypes was conducted under well-watered and managed drought conditions at two sites for 5 years in Cambodia. Water level in the field was recorded and used to estimate the relative water level (WLREL) around flowering as an index of the severity of water deficit at the time of flowering for each entry. This was used to determine if DRI or yield reduction was due to drought tolerance or related to the amount of available water at flowering, i.e. drought escape. Grain yield reduction due to drought ranged from 12 to 46%. The drought occurred mainly during the reproductive phase, while four experiments had water stress from the early vegetative stage. There was significant variation for water availability around flowering among the nine experiments and this was associated with variation in mean yield reduction. Genotypic variation in DRI was consistent among most experiments, and genotypic mean DRI ranged from -0.54 to 0.47 (LSD 5% = 0.47). Genotypic variation in DRI was not related to WLREL around flowering in the nine environments. It is concluded that selection for DRI under drought conditions would allow breeders to identify donor lines with high drought tolerance as an important component of breeding better adapted varieties for the rainfed lowlands; two genotypes were identified with high DRI and low yield reduction and were subsequently used in the breeding program in Cambodia. (c) 2006 Elsevier B.V. All rights reserved.
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In this work we experimentally investigate the response time of humidity sensors based on polymer optical fiber Bragg gratings. By the use of etching with acetone we can control the poly (methyl methacrylate) based fiber in order to reduce the diffusion time of water into the polymer and hence speed up the relative wavelength change caused by humidity variations. A much improved response time of 12 minutes for humidity decrease and 7 minutes for humidity increase, has been achieved by using a polymer optical fiber Bragg grating with a reduced diameter of 135 microns.
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Protein modifications, including oxidative modifications, glycosylations, and oxidized lipid-protein adducts, are becoming increasingly important as biomarkers and in understanding disease etiology. There has been a great deal of interest in mapping these on Apo B100 from low density lipoprotein (LDL). We have used extracted ion chromatograms of product ions generated using a very narrow mass window from high-resolution tandem mass spectrometric data collected on a rapid scanning quadrupole time-of-flight (QTOF) instrument, to selectively and sensitively detect modified peptides and identify the site and nature of a number of protein modifications in parallel. We have demonstrated the utility of this method by characterizing for the first time oxidized phospholipid adducts to LDL and human serum albumin and for the detection of glycosylation and kynurenin formation from the oxidation of tryptophan residues in LDL. © 2013 American Chemical Society.
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Models at runtime can be defined as abstract representations of a system, including its structure and behaviour, which exist in tandem with the given system during the actual execution time of that system. Furthermore, these models should be causally connected to the system being modelled, offering a reflective capability. Significant advances have been made in recent years in applying this concept, most notably in adaptive systems. In this paper we argue that a similar approach can also be used to support the dynamic generation of software artefacts at execution time. An important area where this is relevant is the generation of software mediators to tackle the crucial problem of interoperability in distributed systems. We refer to this approach as emergent middleware, representing a fundamentally new approach to resolving interoperability problems in the complex distributed systems of today. In this context, the runtime models are used to capture meta-information about the underlying networked systems that need to interoperate, including their interfaces and additional knowledge about their associated behaviour. This is supplemented by ontological information to enable semantic reasoning. This paper focuses on this novel use of models at runtime, examining in detail the nature of such runtime models coupled with consideration of the supportive algorithms and tools that extract this knowledge and use it to synthesise the appropriate emergent middleware.
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Service innovations in retailing have the potential to benefit consumers as well as retailers. This research models key factors associated with the trial and continuous use of a specific self-service technology (SST), the personal shopping assistant (PSA), and estimates retailer benefits from implementing that innovation. Based on theoretical insights from prior SST studies, diffusion of innovation literature, and the technology acceptance model (TAM), this study develops specific hypotheses and tests them on a sample of 104 actual users of the PSA and 345 nonusers who shopped at the retail store offering the PSA device. Results indicate that factors affecting initial trial are different from those affecting continuous use. More specifically, consumers' trust toward the retailer, novelty seeking, and market mavenism are positively related to trial, while technology anxiety hinders the likelihood of trying the PSA. Perceived ease of use of the device positively impacts continuous use while consumers' need for interaction in shopping environments reduces the likelihood of continuous use. Importantly, there is evidence on retailer benefits from introducing the innovation since consumers using the PSA tend to spend more during each shopping trip. However, given the high costs of technology, the payback period for recovery of investments in innovation depends largely upon continued use of the innovation by consumers. Important implications are provided for retailers considering investments in new in-store service innovations. Incorporation of technology within physical stores affords opportunities for the retailer to reduce costs, while enhancing service provided to consumers. Therefore, service innovations in retailing have the potential to benefit consumers as well as retailers. This research models key factors associated with the trial and continuous use of a specific SST in the retail context, the PSA, and estimates retailer benefits from implementing that innovation. In so doing, the study contributes to the nascent area of research on SSTs in the retail sector. Based on theoretical insights from prior SST studies, diffusion of innovation literature, and the TAM, this study develops specific hypotheses regarding the (1) antecedent effects of technological anxiety, novelty seeking, market mavenism, and trust in the retailer on trial of the service innovation; (2) the effects of ease of use, perceived waiting time, and need for interaction on continuous use of the innovation; and (3) the effect of use of innovation on consumer spending at the store. The hypotheses were tested on a sample of 104 actual users of the PSA and 345 nonusers who shopped at the retail store offering the PSA device, one of the early adopters of PSA in Germany. Data were analyzed using logistic regression (antecedents of trial), multiple regression (antecedents of continuous use), and propensity score matching (assessing retailer benefits). Results indicate that factors affecting initial trial are different from those affecting continuous use. More specifically, consumers' trust toward the retailer, novelty seeking, and market mavenism are positively related to trial, while technology anxiety hinders the likelihood of trying the PSA. Perceived ease of use of the device positively impacts continuous use, while consumers' need for interaction in shopping environments reduces the likelihood of continuous use. Importantly, there is evidence on retailer benefits from introducing the innovation since consumers using the PSA tend to spend more during each shopping trip. However, given the high costs of technology, the payback period for recovery of investments in innovation depends largely upon continued use of the innovation by consumers. Important implications are provided for retailers considering investments in new in-store service innovations. The study contributes to the literature through its (1) simultaneous examination of antecedents of trial and continuous usage of a specific SST, (2) the demonstration of economic benefits of SST introduction for the retailer, and (3) contribution to the stream of research on service innovation, as against product innovation.