953 resultados para Dam-break
Resumo:
In this dissertation I study language complexity from a typological perspective. Since the structuralist era, it has been assumed that local complexity differences in languages are balanced out in cross-linguistic comparisons and that complexity is not affected by the geopolitical or sociocultural aspects of the speech community. However, these assumptions have seldom been studied systematically from a typological point of view. My objective is to define complexity so that it is possible to compare it across languages and to approach its variation with the methods of quantitative typology. My main empirical research questions are: i) does language complexity vary in any systematic way in local domains, and ii) can language complexity be affected by the geographical or social environment? These questions are studied in three articles, whose findings are summarized in the introduction to the dissertation. In order to enable cross-language comparison, I measure complexity as the description length of the regularities in an entity; I separate it from difficulty, focus on local instead of global complexity, and break it up into different types. This approach helps avoid the problems that plagued earlier metrics of language complexity. My approach to grammar is functional-typological in nature, and the theoretical framework is basic linguistic theory. I delimit the empirical research functionally to the marking of core arguments (the basic participants in the sentence). I assess the distributions of complexity in this domain with multifactorial statistical methods and use different sampling strategies, implementing, for instance, the Greenbergian view of universals as diachronic laws of type preference. My data come from large and balanced samples (up to approximately 850 languages), drawn mainly from reference grammars. The results suggest that various significant trends occur in the marking of core arguments in regard to complexity and that complexity in this domain correlates with population size. These results provide evidence that linguistic patterns interact among themselves in terms of complexity, that language structure adapts to the social environment, and that there may be cognitive mechanisms that limit complexity locally. My approach to complexity and language universals can therefore be successfully applied to empirical data and may serve as a model for further research in these areas.
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Emulsiokalvolla tarkoitetaan kalvoa, joka on valmistettu haihduttamalla ylimääräinen vesi pois emulsiosta. Polysakkaridipohjainen emulsiokalvo koostuu kalvonmuodostuspolysakkaridista, rasvasta, emulgointiaineesta ja pehmittimestä. Kirjallisuusosassa selvitettiin, mitä raaka-aineita polysakkaridipohjaisissa emulsiokalvoissa käytetään ja mitkä tekijät vaikuttavat emulsiokalvojen vesihöyrynläpäisevyyteen ja mekaanisiin ominaisuuksiin. Tutkimuksen kokeellisen osan tavoitteena oli selvittää, miten konjac-glukomannaani (KGM) ja kuusen galaktoglukomannaani (GGM) soveltuvat emulsiokalvon raaka-aineiksi. Lisäksi selvitettiin, miten rasvan tyyppi ja rasvapitoisuus vaikuttavat GGM-KGM-pohjaisten emulsiokalvojen mekaanisiin ominaisuuksiin ja vesihöyrynläpäisevyyteen. Mehiläisvahasta, mäntyöljystä ja rypsiöljystä valmistettiin emulsiokalvot, joissa oli 30 %:n (paino-% GGM:sta) rasvapitoisuudet. Lisäksi mehiläisvahasta valmistettiin emulsiokalvot, joissa oli 10 ja 50 % mehiläisvahaa. Emulsiokalvoja verrattiin vertailukalvoon, jossa ei ollut rasvaa. Kalvoissa käytetty KGM:n ja GGM:n suhde oli 1:1. Kalvoista mitattiin vesihöyrynläpäisevyys ja -läpäisynopeus, vetolujuus, Youngin moduuli ja murtovenymä. Näiden lisäksi kalvojen poikkileikkaus kuvattiin pyyhkäisyelektronimikroskoopilla. GGM ja KGM soveltuvat emulsiokalvon raaka-aineiksi. Huoneenlämpötilassa kuivatuista kalvoista saatiin tasaisemman näköisiä kuin lämpökaapissa kuivatuista. Pyyhkäisyelektronimikroskooppikuvissa vahapisarat olivat öljypisaroita pienempiä, mikä mahdollisesti vaikutti siihen, että vahapisarat pysyivät paremmin kiinnittyneenä kalvomatriisissa. Öljypisaroiden koko oli kalvoissa noin 10 ?m ja vahapisaroiden 2–6 ?m. Vesihöyrynläpäisynopeus oli pienin 50 %:n mehiläisvahakalvolla (p < 0,05). Vesihöyrynläpäisevyys laski lineaarisesti mehiläisvahapitoisuuden suurentuessa. Öljykalvot ja 10 %:n mehiläisvahakalvo eivät eronneet tilastollisesti merkitsevästi vesihöyrynläpäisevyyden suhteen vertailukalvosta. Pienin vetolujuus ja Youngin moduuli oli 50 %:n mehiläisvahakalvolla. Vertailukalvo oli kestävin ja jäykin. Murtovenymän suhteen kalvot eivät eronneet toisistaan tilastollisesti merkitsevästi. Tutkimuksessa onnistuttiin valmistamaan GGM-KGM-pohjaisia emulsiokalvoja, jotka pidättivät vesihöyryä vertailukalvoa paremmin ja silti säilyttivät mekaaniset ominaisuutensa kohtuullisen hyvin.
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A local algorithm with local horizon r is a distributed algorithm that runs in r synchronous communication rounds; here r is a constant that does not depend on the size of the network. As a consequence, the output of a node in a local algorithm only depends on the input within r hops from the node. We give tight bounds on the local horizon for a class of local algorithms for combinatorial problems on unit-disk graphs (UDGs). Most of our bounds are due to a refined analysis of existing approaches, while others are obtained by suggesting new algorithms. The algorithms we consider are based on network decompositions guided by a rectangular tiling of the plane. The algorithms are applied to matching, independent set, graph colouring, vertex cover, and dominating set. We also study local algorithms on quasi-UDGs, which are a popular generalisation of UDGs, aimed at more realistic modelling of communication between the network nodes. Analysing the local algorithms on quasi-UDGs allows one to assume that the nodes know their coordinates only approximately, up to an additive error. Despite the localisation error, the quality of the solution to problems on quasi-UDGs remains the same as for the case of UDGs with perfect location awareness. We analyse the increase in the local horizon that comes along with moving from UDGs to quasi-UDGs.
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Work has a central role in the lives of big share of adult Finns and meals they eat during the workday comprise an important factor in their nutrition, health, and well-being. On workdays, lunch is mainly eaten at worksite canteens or, especially among women, as a packed meal in the workplace s break room. No national-level data is available on the nutritional quality of the meals served by canteens, although the Finnish Institute of Occupational Health laid out the first nutrition recommendations for worksite canteens in 1971. The aim of this study was to examine the contribution of various socio-demographic, socioeconomic, and work-related factors to the lunch eating patterns of Finnish employees during the working day and how lunch eating patterns influence dietary intake. Four different population-based cross-sectional datasets were used in this thesis. Three of the datasets were collected by the National Institute for Health and Welfare (Health Behaviour and Health among the Finnish Adult Population survey from 1979 to 2001, n=24746, and 2005 to 2007, n=5585, the National Findiet 2002 Study, n=261), and one of them by the Finnish Institute of Occupational Health (Work and Health in Finland survey from 1997, 2000, and 2003, n=6369). The Health Behaviour and Health among the Finnish Adult Population survey and the Work and Health in Finland survey are nationally representative studies that are conducted repeatedly. Survey information was collected by self-administered questionnaires, dietary recalls, and telephone interviews. The frequency of worksite canteen use has been quite stable for over two decades in Finland. A small decreasing trend can be seen in all socioeconomic groups. During the whole period studied, those with more years of education ate at worksite canteens more often than the others. The size of the workplace was the most important work-related determinant associated with the use of a worksite canteen. At small workplaces, other work-related determinants, like occupation, physical strain at work, and job control, were also associated with canteen use, whereas at bigger workplaces the associations were almost nonexistent. The major social determinants of worksite canteen availability were the education and occupational status of employees and the only work-related determinant was the size of the workplace. A worksite canteen was more commonly available to employees at larger workplaces and to those with the higher education and the higher occupational status. Even when the canteen was equally available to all employees, its use was nevertheless determined by occupational class and the place of residence, especially among female employees. Those with higher occupational status and those living in the Helsinki capital area ate in canteens more frequently than the others. Employees who ate at a worksite canteen consumed more vegetables and vegetable and fish dishes at lunch than did those who ate packed lunches. Also, the daily consumption of vegetables and the proportion of the daily users of vegetables were higher among those male employees who ate at a canteen. In conclusion, life possibilities, i.e. the availability of a canteen, education, occupational status, and work-related factors, played an important role in the choice of where to eat lunch among Finnish employees. The most basic prerequisite for eating in a canteen was availability, but there were also a number of underlying social determinants. Occupational status and the place of residence were the major structural factors behind individuals choices in their lunch eating patterns. To ensure the nutrition, health, and well-being of employees, employers should provide them with the option to have good quality meals during working hours. The availability of worksite canteens should be especially supported in lower socioeconomic groups. In addition, employees should be encouraged to have lunch at a worksite canteen when one is available by removing structural barriers to its use.
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Germline mutations in many of the genes that are involved in homologous recombination (HR)-mediated DNA double-strand break repair (DSBR) are associated with various human genetic disorders and cancer. RAD51 and RAD51 paralogs are important for HR and in the maintenance of genome stability. Despite the identification of five RAD51 paralogs over a decade ago, the molecular mechanism(s) by which RAD51 paralogs regulate HR and genome maintenance remains obscure. In addition to the known roles of RAD51C in early and late stages of HR, it also contributes to activation of the checkpoint kinase CHK2. One recent study identifies biallelic mutation in RAD51C leading to Fanconi anemia-like disorder. Whereas a second study reports monoallelic mutation in RAD51C associated with increased risk of breast and ovarian cancer. These reports show RAD51C is a cancer susceptibility gene. In this review, we focus on describing the functions of RAD51C in HR, DNA damage signaling and as a tumor suppressor with an emphasis on the new roles of RAD51C unveiled by these reports.
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Static and vibration problems of an indeterminate continuum are traditionally analyzed by the stiffness method. The force method is more or less non-existent for such problems. This situation is primarily due to the incomplete state of development of the compatibility conditions which are essential for the analysis of indeterminate structures by the flexibility method. The understanding of the Compatibility Conditions (CC) has been substantially augmented. Based on the understanding of CC, a novel formulation termed the Integrated Force Method (IFM) has been established. In this paper IFM has been extended for the static and vibration analyses of a continuum. The IFM analysis is illustrated taking three examples: 1. (1) rectangular plate in flexure 2. (2) analysis of a cantilevered dam 3. (3) free vibration analysis of a beam. From the examples solved it is observed that the force response of an indeterminate continuum with mixed boundary conditions can be generated by IFM without any reference to displacements in the field or on the boundary. Displacements if required can be calculated by back substitution.
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Measurements of the electrical resistivity of thin potassium wires at temperatures near 1 K have revealed a minimum in the resistivity as a function of temperature. By proposing that the electrons in these wires have undergone localization, albeit with large localization length, and that inelastic-scattering events destroy the coherence of that state, we can explain both the magnitude and shape of the temperature-dependent resistivity data. Localization of electrons in these wires is to be expected because, due to the high purity of the potassium, the elastic mean free path is comparable to the diameters of the thinnest samples, making the Thouless length lT (or inelastic diffusion length) much larger than the diameter, so that the wire is effectively one dimensional. The inelastic events effectively break the wire into a series of localized segments, whose resistances can be added to obtain the total resistance of the wire. The ensemble-averaged resistance for all possible segmented wires, weighted with a Poisson distribution of inelastic-scattering lengths along the wire, yields a length dependence for the resistance that is proportional to [L3/lin(T)], provided that lin(T)?L, where L is the sample length and lin(T) is some effective temperature-dependent one-dimensional inelastic-scattering length. A more sophisticated approach using a Poisson distribution in inelastic-scattering times, which takes into account the diffusive motion of the electrons along the wire through the Thouless length, yields a length- and temperature-dependent resistivity proportional to (L/lT)4 under appropriate conditions. Inelastic-scattering lifetimes are inferred from the temperature-dependent bulk resistivities (i.e., those of thicker, effectively three-dimensional samples), assuming that a minimum amount of energy must be exchanged for a collision to be effective in destroying the phase coherence of the localized state. If the dominant inelastic mechanism is electron-electron scattering, then our result, given the appropriate choice of the channel number parameter, is consistent with the data. If electron-phason scattering were of comparable importance, then our results would remain consistent. However, the inelastic-scattering lifetime inferred from bulk resistivity data is too short. This is because the electron-phason mechanism dominates in the inelastic-scattering rate, although the two mechanisms may be of comparable importance for the bulk resistivity. Possible reasons why the electron-phason mechanism might be less effective in thin wires than in bulk are discussed.
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The steady laminar compressible boundary layer flow of an electrically conducting fluid in the stagnation region of a sphere with an applied magnetic field has been studied. The effects of the induced magnetic field, mass transfer, and viscous dissipation have been taken into account. Both isothermal and adiabatic wall conditions have been considered. The governing equations have been solved numerically using a shooting method. The skin friction and heat transfer are found to be strongly affected by the magnetic field, mass transfer, wall temperature and Mach number. It is found that the magnetic field reduces the heat transfer. This is a significant result which can be used in controlling the heat transfer rate. The boundary layer solutions break down as the magnetic parameter tends to a certain critical value.
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This article examines the changes in interparticle forces brought about on prolonged contact (1 year period) of a bentonite clay with artificial seawater. The study is undertaken with the purpose of identifying the physico-chemical factors that impart a nonswelling character to smectite clays deposited in marine environments. Results show that equilibration of the bentonite clay with artificial seawater (total pore salinity approximately 42 gL-1) for a 1 year period does not lead to any mineralogical changes in the clay specimens; however, their exchangeable cation positions become prominently dominated by magnesium ions. The consistency limits of the seawater-equilibrated bentonite was determined on stepwise leaching to lower salinities. The predominance of diffuse double-layer repulsion forces in the pore salt concentration range of 42 gL-1 to 1.1 gL-1 caused an increase in the liquid limits of the seawater-equilibrated bentonite specimens on reducing the salinity in the corresponding range (42 gL-1 to 1.1 gL-1). The attraction forces, however, prevail over the repulsion forces at salt concentrations <1.1 gL-1 and cause a decrease in liquid limit of the clay specimens with reduction in pore salinity, which is typical of nonswelling clays. The attraction forces cause aggregation of the clay unit layers into domains that break down on sodium saturation of the clay specimens. It is inferred that the physico-chemical factors responsible for the nonswelling character of the seawater-equilibrated bentonite specimens at pore salt concentrations below 1.1 gL-1 are inadequate to explain the nonswelling character of smectite-rich Ariake marine clays. The lower consistency limits of the Ariake marine clays in comparison to the nonswelling character, seawater-equilibrated bentonite specimens is attributed to a relative deficiency of interparticle forces in the Ariake marine clay.
Resumo:
In this work, we present a new monolithic strategy for solving fluid-structure interaction problems involving incompressible fluids, within the context of the finite element method. This strategy, similar to the continuum dynamics, conserves certain properties, and thus provides a rational basis for the design of the time-stepping strategy; detailed proofs of the conservation of these properties are provided. The proposed algorithm works with displacement and velocity variables for the structure and fluid, respectively, and introduces no new variables to enforce velocity or traction continuity. Any existing structural dynamics algorithm can be used without change in the proposed method. Use of the exact tangent stiffness matrix ensures that the algorithm converges quadratically within each time step. An analytical solution is presented for one of the benchmark problems used in the literature, namely, the piston problem. A number of benchmark problems including problems involving free surfaces such as sloshing and the breaking dam problem are used to demonstrate the good performance of the proposed method. Copyright (C) 2010 John Wiley & Sons, Ltd.
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It is found that the inclusion of higher derivative terms in the gravitational action along with concepts of phase transition and spontaneous symmetry breaking leads to some novel consequence. The Ricci scalar plays the dual role, like a physical field as well as a geometrical field. One gets Klein-Gordon equation for the emerging field and the corresponding quanta of geometry are called Riccions. For the early universe the model removes singularity along with inflation. In higher dimensional gravity the Riccions can break into spin half particle and antiparticle along with breaking of left-right symmetry. Most tantalizing consequences is the emergence of the physical universe from the geometry in the extreme past. Riccions can Bose condense and may account for the dark matter.
Resumo:
Cardiac arrhythmias, such as ventricular tachycardia (VT) and ventricular fibrillation (VF), are among the leading causes of death in the industrialized world. These are associated with the formation of spiral and scroll waves of electrical activation in cardiac tissue; single spiral and scroll waves are believed to be associated with VT whereas their turbulent analogs are associated with VF. Thus, the study of these waves is an important biophysical problem. We present a systematic study of the combined effects of muscle-fiber rotation and inhomogeneities on scroll-wave dynamics in the TNNP (ten Tusscher Noble Noble Panfilov) model for human cardiac tissue. In particular, we use the three-dimensional TNNP model with fiber rotation and consider both conduction and ionic inhomogeneities. We find that, in addition to displaying a sensitive dependence on the positions, sizes, and types of inhomogeneities, scroll-wave dynamics also depends delicately upon the degree of fiber rotation. We find that the tendency of scroll waves to anchor to cylindrical conduction inhomogeneities increases with the radius of the inhomogeneity. Furthermore, the filament of the scroll wave can exhibit drift or meandering, transmural bending, twisting, and break-up. If the scroll-wave filament exhibits weak meandering, then there is a fine balance between the anchoring of this wave at the inhomogeneity and a disruption of wave-pinning by fiber rotation. If this filament displays strong meandering, then again the anchoring is suppressed by fiber rotation; also, the scroll wave can be eliminated from most of the layers only to be regenerated by a seed wave. Ionic inhomogeneities can also lead to an anchoring of the scroll wave; scroll waves can now enter the region inside an ionic inhomogeneity and can display a coexistence of spatiotemporal chaos and quasi-periodic behavior in different parts of the simulation domain. We discuss the experimental implications of our study.
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Within the summer monsoon, the circulation and rainfall over the Indian region exhibit large variations over the synoptic scale of 3-7 days and the supersynoptic scales of 10 days and longer. In this paper we discuss some facets of intraseasonal variation on the supersynoptic scale on the basis of existing observational studies and some new analysis. The major variation of the summer monsoon rainfall on this scale is the active-break cycle. The deep convection over the Indian region on a typical day in the active phase is organized over thousands of kilometers in the zonal direction and is associated with a tropical convergence zone (TCZ). The intraseasonal variations on the supersynoptic scale are also coherent on these scales and are related to the space-time variation of the large-scale TCZ. The latitudinal distribution of the occurrence of the TCZ is bimodal with the primary mode over the heated continent and a secondary mode over the ocean. The variation of the continental TCZ is generally out of phase with that of the oceanic TCZ. During the active spells, the TCZ persists over the continent in the monsoon zone. The revival from breaks occurs either by northward propagation of the TCZ over the equatorial Indian Ocean or by genesis of a disturbance in the monsoon zone (often as a result of westward propagations from W. Pacific). The mechanisms governing the fluctuation between active spells and breaks, the interphase transition and the complex interactions of the TCZ over the Indian subcontinent with the TCZ over the equatorial Indian Ocean and the W. Pacific, have yet to be completely understood.
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Interaction between two conical sheets of liquid formed by a coaxial swirl injector has been studied using water in the annular orifice and potassium permanganate solution in the inner orifice. Experiments using photographic techniques have been conducted to study the influence of the inner jet on outer conical sheet spray characteristics such as spray cone angle and break-up length. The core spray has a strong influence on the outer sheet when the pressure drop in the latter is low. This is attributed to the pressure variations caused by ejector effects. This paper also discusses the merging and separation behavior of the liquid sheets which exhibits hysteresis effect while injector pressure drop is varied.
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The problem of determining optimal power spectral density models for earthquake excitation which satisfy constraints on total average power, zero crossing rate and which produce the highest response variance in a given linear system is considered. The solution to this problem is obtained using linear programming methods. The resulting solutions are shown to display a highly deterministic structure and, therefore, fail to capture the stochastic nature of the input. A modification to the definition of critical excitation is proposed which takes into account the entropy rate as a measure of uncertainty in the earthquake loads. The resulting problem is solved using calculus of variations and also within linear programming framework. Illustrative examples on specifying seismic inputs for a nuclear power plant and a tall earth dam are considered and the resulting solutions are shown to be realistic.