984 resultados para Lead times


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Distraction resulting from mobile phone use whilst driving has been shown to increase the reaction times of drivers, thereby increasing the likelihood of a crash. This study compares the effects of mobile phone conversations on reaction times of drivers responding to traffic events that occur at different points in a driver’s field of view. The CARRS-Q Advanced Driving Simulator was used to test a group of young drivers on various simulated driving tasks including a traffic event that occurred within the driver’s central vision—a lead vehicle braking suddenly—and an event that occurred within the driver’s peripheral—a pedestrian entering a zebra crossing from a footpath. Thirty-two licensed drivers drove the simulator in three phone conditions: baseline (no phone conversation), and while engaged in hands-free and handheld phone conversations. The drivers were aged between 21 to 26 years and split evenly by gender. Differences in reaction times for an event in a driver’s central vision were not statistically significant across phone conditions, probably due to a lower speed selection by the distracted drivers. In contrast, the reaction times to detect an event that originated in a distracted driver’s peripheral vision were more than 50% longer compared to the baseline condition. A further statistical analysis revealed that deterioration of reaction times to an event in the peripheral vision was greatest for distracted drivers holding a provisional licence. Many critical events originate in a driver’s periphery, including vehicles, bicyclists, and pedestrians emerging from side streets. A reduction in the ability to detect these events while distracted presents a significant safety concern that must be addressed.

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In recent times antiferroelectric thin-film material compositions have been identified as one of the most significant thin films for development of devices such as high charge storage, charge couplers/decouplers, and high strain microelectromechanical systems. Thus, understanding the dielectric and electrical properties under an ac signal drive in these antiferroelectric thin-film compositions, such as lead zirconate thin films, and the effect of donor doping on them is very necessary. For this purpose, thin films of antiferroelectric lead zirconate and La-modified lead zirconate thin films with mole % concentrations of 0, 3, 5, and 9 have been deposited by pulsed excimer laser ablation. The dielectric and hysteresis properties have confirmed that with a gradual increase of the La content, the room-temperature antiferroelectric lead zirconate thin films can be modified into ferroelectric and paraelectric phases. ac electrical studies revealed that the polaronic related hopping conduction is responsible for the charge transport phenomenon in these films. With a La content of less than or equal to3 mole % in pure lead zirconate, the conductivity of the films has been reduced and followed by an increase of its conductivity for a greater than or equal to3% addition of La to lead zirconate thin films. The polaronic activation energies are also found to follow a similar trend as that of the conductivity.

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A novel Nd3+-doped lead fluorosilicate glass (NPS glass) is prepared by a two-step melting process. Based on the absorption spectrum a Judd-Ofelt theory analysis is made. The emission line width of NPS glass is 44.2nm. The fluorescence decay lifetime of the 4F3/2 level is 586±20μsec, and the stimulated emission cross-section is 0.87×10-20cm2 at 1056nm. A laser oscillation is occurred at 1062nm when pumped by 808nm Diode Laser. The slope efficiency is 23.7% with a 415mJ threshold. It is supposed that NPS glass is a good candidate for using in ultra-short pulse generation and amplification by the broad emission bandwidth and long fluorescence lifetime.

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In wetland-adapted plants, such as rice, it is typically root apexes, sites of rapid entry for water/nutrients, where radial oxygen losses (ROLs) are highest. Nutrient/toxic metal uptake therefore largely occurs through oxidized zones and pH microgradients. However, the processes controlling the acquisition of trace elements in rice have been difficult to explore experimentally because of a lack of techniques for simultaneously measuring labile trace elements and O2/pH. Here, we use new diffusive gradients in thin films (DGT)/planar optode sandwich sensors deployed in situ on rice roots to demonstrate a new geochemical niche of greatly enhanced As, Pb, and Fe(II) mobilization into solution immediately adjacent to the root tips characterized by O2 enrichment and low pH. Fe(II) mobilization was congruent to that of the peripheral edge of the aerobic root zone, demonstrating that the Fe(II) mobilization maximum only developed in a narrow O2 range as the oxidation front penetrates the reducing soil. The Fe flux to the DGT resin at the root apexes was 3-fold higher than the anaerobic bulk soil and 27 times greater than the aerobic rooting zone. These results provide new evidence for the importance of coupled diffusion and oxidation of Fe in modulating trace metal solubilization, dispersion, and plant uptake.

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Teollisuuden palveluiden on huomattu olevan potentiaalinen lisätulojen lähde. Teollisuuden palveluiden dynaamisessa maailmassa räätälöinti ja kyky toimia nopeasti ovat kriittisiä asiakastyytyväisyyden ja kilpailuedun luomisprosessin osia. Toimitusketjussa käytetyn ajan lyhentämisellä voidaan saavuttaa sekä paremmat vasteajat, että alhaisemmat kokonaiskustannukset. Tutkielman tavoitteena on kuvata teollisuuden palveluiden dynaamista ympäristöä: asiakastarvetta, sekä mahdollisuuksia kaventaa pyydetyn ja saavutetun toimitusajan välistä eroa. Tämä toteutetaan pääosin strategisen toimitusajan hallinnan keinoin. Langattomien tietoliikenneverkkojen operaattorit haluavat vähentää ydinosaamiseensa kuulumatomiin toimintoihin, kuten ylläpitoon sitoutuneita pääomia. Tutkielman case osiossa varaosapalvelujen toimitusketjun kysyntä-, materiaali- ja informaatiovirtoja analysoidaan niin kvalitatiivisten haastatteluiden, sisäisten dokumenttien, kuin kvantitatiivisten tilastollisten menetelmienkin avulla. Löydöksiä peilataan vallitsevaa toimitusketjun ja ajanhallinnan paradigmaa vasten. Tulokset osoittavat, että vahvan palvelukulttuurin omaksuminen ja kokonaisvaltainen toimitusketjun tehokkuuden mittaaminen ovat ajanhallinnan lähtökohtia teollisuuden palveluissa.

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The rapid growth of the populous Asian economies provokes profound economic changes and a shift in the balance of power. On the economic front, Asian leaders are confronted with the need to preserve the stability that has underpinned their prosperity, maintain an environment conducive to trade and investments and encourage domestic consumption while avoiding ecological disasters. Internationally, business competition will intensify with the strong presence of Asian manufacturers in global supply chains, growing price competition from Asian firms in domestic markets and global competition for energy, food, minerals and other commodities. Geopolitical concerns stem, in part, from Asia’s global quest for critical resources, conflicting territorial and maritime disputes and increasing military expenditures which affect security dynamics. China’s assertiveness over its periphery prompts an arm’s race in the region and concerns about Sino-American relations even though U.S.-Chinese relations may be less risky than China’s relations with its neighbours. The United States remains a key player in the Asia-Pacific region, with the capacity to alter balances and affect outcomes. Globally, the United States capacity to lead is now diminished and will continue to be so for the foreseeable future. Since no rising power is capable of exercising global leadership, a return to the "old normal" where no one power in geopolitical or economic terms dominates the world is to be expected.

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The investigation of physical properties of matter has progressed so much during the last hundred years. Today physics is divided in to a large distinct group of special branches. These branches are distinguished by the particular area studied, method of investigation and so on. An independent and important branch that has developed is the physics ofthin films.Any object in solid or liquid form with one of its dimensions very much smaller than that of the other two may be called a thin film. It is having only one common property, namely, one of their dimensions is very small, though all their physical properties may be different. Thin layers of oil, floating on the surface of water, with their fascinating colours, have attracted men’s curiosity from time immemorial. The earliest application of thin films was the protective coatings in the form of paints. A thin layer of tin has been used from ancient times to protect copper utensils from corrosion. Indium thin films are used in certain applications on account of their good lubricating property. Relay contacts are coated with thin films of rare earth metals in order to prevent burning due to arcing. Hard coatings are also available using diamond like carbon (i-carbon). The basic properties of thin films are of considerable interest because of their potential applications in various fields of science and technology

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Internationally agreed standard protocols for assessing chemical toxicity of contaminants in soil to worms assume that the test soil does not need to equilibrate with the chemical to be tested prior to the addition of the test organisms and that the chemical will exert any toxic effect upon the test organism within 28 days. Three experiments were carried out to investigate these assumptions. The first experiment was a standard toxicity test where lead nitrate was added to a soil in solution to give a range of concentrations. The mortality of the worms and the concentration of lead in the survivors were determined. The LC(50)s for 14 and 28 days were 5311 and 5395 mug(Pb) g(soil)(-1) respectively. The second experiment was a timed lead accumulation study with worms cultivated in soil containing either 3000 or 5000 mug(Pb) g(soil)(-1). The concentration of lead in the worms was determined at various sampling times. Uptake at so' Sol both concentrations was linear with time. Worms in the 5000 mug g(-1) soil accumulated lead at a faster rate (3.16 mug Pb g(tissue)(-1) day(-1)) tiss than those in the 3000 mug g(-1) soil (2.21 mug Pb-tissue g(-1) day(-1)). The third experiment was a timed experiment with worms cultivated in tiss soil containing 7000 mugPb g(soil)(-1). Soil and lead nitrate solution were mixed and stored at 20 degreesC. Worms were added at various times over a 35-day period. The time to death increased from 23 h, when worms were added directly after the lead was added to the soil, to 67 It when worms were added after the soil had equilibrated with the lead for 35 days. In artificially Pb-amended soils the worms accumulate Pb over the duration of their exposure to the Pb. Thus time limited toxicity tests may be terminated before worm body load has reached a toxic level. This could result in under-estimates of the toxicity of Pb to worms. As the equilibration time of artificially amended Pb-bearing soils increases the bioavailability of Pb decreases. Thus addition of worms shortly after addition of Pb to soils may result in the over-estimate of Pb toxicity to worms. The current OECD acute worm toxicity test fails to take these two phenomena into account thereby reducing the environmental relevance of the contaminant toxicities it is used to calculate. (C) 2002 Elsevier Science Ltd. All rights reserved.

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Leading time length is an important issue for modeling seasonal forecasts. In this study, a comparison of the interannual predictability of the Western North Pacific (WNP) summer monsoon between different leading months was performed by using one-, four-, and seven-month lead retrospective forecasts (hindcasts) of four coupled models from Ensembles-Based Predictions of Climate Changes and Their Impacts (ENSEMBLES) for the period of 1960-2005. It is found that the WNP summer anomalies, including lower-tropospheric circulation and precipitation anomalies, can be well predicted for all these leading months. The accuracy of the four-month lead prediction is only slightly weaker than that of the one-month lead prediction, although the skill decreases with the increase of leading months.

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The third-order optical susceptibility and dispersion of the linear refractive index of Er(3+)-doped lead phosphate glass were measured in the wavelength range between 400 and 1940 nm by using the spectrally resolved femtosecond Maker fringes technique. The nonlinear refractive index obtained from the third-order susceptibility was found to be five times higher than that of silica, indicating that Er(3+)-doped lead phosphate glass is a potential candidate to be used as the base component for the fabrication of photonic devices. For comparison purposes, the Z-scan technique was also employed to obtain the values of the nonlinear refractive index of Er(3+)-doped lead phosphate glass at several wavelengths, and the values obtained using the two techniques agree to within 15%.

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The paper observes a number of possible changes impacting on the field of distance education research and suggests that these are likely to have lead to an increasing interest in research on computer-based instructional design and delivery, and a concomitant decrease in interest in other areas of distance education research. A fairly simple analysis of contributions to Distance Education since 1980 bears out the suggestion. Some opportunities and some threats to distance education as a field are discussed as a consequence of the analysis.

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Migrants, such as birds or representatives of other taxa, usually make use of several stopover sites to cover the distance between their site of origin and destination. Potentially, multiple routes exist, but often little is known about the causes and consequences of alternative migration routes. Apart from their geographical distribution, the suitability of potential sites might play an important role in the animals’ decisions for a particular itinerary. We used an optimal-migration model to test three nonmutually exclusive hypotheses leading to variations in the spring migration routes of a subspecies of Red Knot, Calidris canutus islandica, which migrates from wintering grounds in Western Europe to breeding grounds in Greenland and the Canadian Arctic: the breeding location hypothesis, the energy budget hypothesis, and the predation risk hypothesis. Varying only breeding location, the model predicted that birds breeding in the Canadian Arctic and on West Greenland stop over on Iceland, whereas birds breeding in East and Northeast Greenland migrate via northern Norway, a prediction that is supported by empirical findings. Energy budgets on stopover sites had a strong influence on the choice of route and staging times. Varying foraging-intensity and mass-dependent predation risk prompted the birds to use less risky sites, if possible. The effect of simultaneous changes in the energy budget and predation risk strongly depended on the site where these occurred. Our findings provide potential explanations for the observations that C. canutus islandica uses a diverse array of migration routes. Scrutinizing the three alternative driving forces for the choice of migratory routes awaits further, specific data collection in rapidly developing fields of research (e.g., predation risk assessment, GPS tracking). Generally, the type of modeling presented here may not only highlight alternative explanations, but also direct follow-up empirical research.

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Everything before the election seemed to be pointing to a Labour lead. Even pollsters got it wrong. But a network analysis of the Twitter conversations about the general election highlights just how much hype there was around Labour in the run-up to the big day. Marco Ruediger and this colleagues at the department of public policy analysis at the Fundação Getulio Vargas in Rio de Janeiro analysed and visualised millions of tweets during the campaign.

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This paper reports a study regarding the distribution of lead in the organic matter fractions of a loamy oxisol treated with stable manure, and its effect on the soil microbial biomass. The experimental design was a completely randomized factorial with three replicates. Treatments were four lead (Pb) rates (0, 200, 400, and 600 mg kg(-1) soil), two levels of manure (0 and 30 Mg ha(-1)) and two sampling times (30 and 60 days after lead application). Total and soil lead soluble in Mehlich 1 extractant, and Ph in the different fractions of the organic matter (fulvic acid, humic acid, and residual) were evaluated along with the soil microbial biomass. Data showed that lead, applied as PbCl2, was concentrated in the residual fraction. The application of manure at the rate of 30 Mg ha(-1) did not affect lead distribution in the fractions until 60 days after incorporation. Lead extracted by Mehlich 1 increased as function of the quantity applied. Manure stimulated the growth of the soil microbial biomass which was reduced by the 200 mg kg(-1) doses of lead, with manure application, increasing, however, with larger rates. Mehlich 1 extracted only part of the lead present in the residual fraction.