On the two-dimensional thermoelectric power in quantum wells of non-parabolic materials under magnetic quantization

We present a simplified theoretical formulation of the thermoelectric power (TP) under magnetic quantization in quantum wells (QWs) of nonlinear optical materials on the basis of a newly formulated magneto-dispersion law. We consider the anisotropies in the effective electron masses and the spin-orbit constants within the framework of k.p formalism by incorporating the influence of the crystal field splitting. The corresponding results for III-V materials form a special case of our generalized analysis under certain limiting conditions. The TP in QWs of Bismuth, II-VI, IV-VI and stressed materials has been studied by formulating appropriate electron magneto-dispersion laws. We also address the fact that the TP exhibits composite oscillations with a varying quantizing magnetic field in QWs of n-Cd3As2, n-CdGeAs2, n-InSb, p-CdS, stressed InSb, PbTe and Bismuth. This reflects the combined signatures of magnetic and spatial quantizations of the carriers in such structures. The TP also decreases with increasing electron statistics and under the condition of non-degeneracy, all the results as derived in this paper get transformed into the well-known classical equation of TP and thus confirming the compatibility test. We have also suggested an experimental method of determining the elastic constants in such systems with arbitrary carrier energy spectra from the known value of the TP. (C) 2010 Elsevier Ltd. All rights reserved.

Analysis of flow near a dug well in an unconfined aquifer

A numerical analysis of flow to a dug well in an unconfined aquifer is made, taking into account well storage, elastic storage release, gravity drainage, anisotropy, partial penetration, vertical flow and seepage surface at the well face, and treating the water table in the aquifer and water level in the well as unknown boundaries. The pumped discharge is maintained constant. The solution is obtained by a two-level iterative scheme. The effects of governing parameters on the drawdown, development of seepage surface and contribution from aquifer flow to the total discharge are discussed. The degree of anisotropy and partial penetration are found to be the parameters which affect the flow characteristics most significantly. The effect of anisotropy on the development of seepage surface is very pronounced.

A Numerical-Simulation Of The Gneiss-Charnockite Transformations In Southern India

This paper presents a numerical simulation of the well-documented, fluid-controlled Kabbal and Ponmudi type gneiss-chamockite transformations in southern India using a free energy minimization method. The computations have considered all the major solid phases and important fluid species in the rock - C-O-H and rock - C-O-H-N systems. Appropriate activity-composition relations for the solid solutions and equations of state for the fluids have been included in order to evaluate the mineral-fluid equilibria attending the incipient chamockite development in the gneisses. The C-O-H fluid speciation pattern in both the Kabbal and Ponmudi type systems indicates that CO2 and H2O make up the bulk of the fluid phase with CO, CH4, H-2 and O2 as minor constituents. In the graphite-buffered Ponmudi-system, the abundance of CO, CH4 and H-2 is orders of magnitude higher than that in the graphite-free Kabbal system. Simulation with C-O-H-N fluids of varying composition demonstrates the complementary role of CO2 and N2 as rather inert dilutants of H2O in the fluid phase. The simulation, carried out on available whole-rock data, has demonstrated the dependence of the transformation X(H2O) on P,T, and phase and chemical composition of the precursor gneiss.

Focal plane analysis of the Knox-Thompson algorithm in speckle interferometry

For the specific case of binary stars, this paper presents signal-to-noise ratio (SNR) calculations for the detection of the parity (the side of the brighter component) of the binary using the double correlation method. This double correlation method is a focal plane version of the well-known Knox-Thompson method used in speckle interferometry. It is shown that SNR for parity detection using double correlation depends linearly on binary separation. This new result was entirely missed by previous analytical calculations dealing with a point source. It is concluded that, for magnitudes relevant to the present day speckle interferometry and for binary separations close to the diffraction limit, speckle masking has better SNR for parity detection.

Precarious Pregnancies : Alcohol, drugs and the regulation of risks

Since the 1970s alcohol and drug use by pregnant women has become a target of political, professional and personal concern. The present study focuses on prenatal substance use and the regulation of risks by examining different kinds of societal responses to prenatal alcohol and drug use. The study analyses face-to-face encounters between professionals and service users at a specialised maternity clinic for pregnant women with substance abuse problems, medical and political discourses on the compulsory treatment of pregnant women as a means of FAS prevention and official recommendations on alcohol intake during pregnancy. Moreover, the study addresses the women s perspective by asking how women who have used illicit drugs during pregnancy perceive and rank the dangers linked to drug use. The study consists of five empirical sub-studies and a summary article. Sub-study I was written in collaboration with Dorte Hecksher and Sub-study IV with Riikka Perälä. Theoretically the study builds on the one hand, on the socio-cultural approach to the selection and perception of risks and on the other on governmentality studies which focus on the use of power in contemporary Western societies. The study is based on an ethnographic approach and makes use of the principles of multi-sited ethnography. The empirical sub-studies are based on three different types of qualitative data: ethnographic field notes from a maternity clinic from a period of 7 months, documentary material (medical journals, political documents, health education materials, government reports) and 3) interviews from maternity clinics with clients and members of staff. The study demonstrates that the logic of the regulation of prenatal alcohol use in Finland is characterised by the rise of the foetus , a process in which the urgency of protecting the foetus has gradually gained a more prominent role in the discourses on alcohol-related foetal damage. An increasing unwillingness to accept any kinds of risks when foetal health is at stake is manifested in the public debate on the compulsory treatment of pregnant women with alcohol problems and in the health authorities decision to advise pregnant women to refrain from alcohol use during pregnancy (Sub-studies I and II). Secondly, the study suggests that maternity care professionals have an ambivalent role in their mundane encounters with their pregnant clients: on the one hand professionals focus on the well-being of the foetus, but on the other, they need to take into account the women s needs and agency. The professionals daily encounters with their clients are thus characterised by hybridisation: the simultaneous use of technologies of domination and technologies of agency (Sub-studies III and IV). Finally, the study draws attention to the women s understanding of the risks of illicit drug during pregnancy, and shows that the women s understanding of risk differs from the bio-medical view. The study suggests that when drug-using pregnant women seek professional help they can feel that their moral worth is threatened by professionals negative attitudes which can make service-use challenging.

The Effect of Food-Related Lifestyle on the Choices of Consumers of Five Food Products

The purpose of this study was to find out whether food-related lifestyle guides and explains product evaluations, specifically, consumer perceptions and choice evaluations of five different food product categories: lettuce, mincemeat, savoury sauce, goat cheese, and pudding. The opinions of consumers who shop in neighbourhood stores were considered most valuable. This study applies means-end chain (MEC) theory, according to which products are seen as means by which consumers attain meaningful goals. The food-related lifestyle (FRL) instrument was created to study lifestyles that reflect these goals. Further, this research has adopted the view that the FRL functions as a script which guides consumer behaviour. Two research methods were used in this study. The first was the laddering interview, the primary aim of which was to gather information for formulating the questionnaire of the main study. The survey consisted of two separate questionnaires. The first was the FRL questionnaire modified for this study. The aim of the other questionnaire was to determine the choice criteria for buying five different categories of food products. Before these analyses could be made, several data modifications were made following MEC analysis procedures. Beside forming FRL dimensions by counting sum-scores from the FRL statements, factor analysis was run in order to elicit latent factors underlying the dimensions. The lifestyle factors found were adventurous, conscientious, enthusiastic, snacking, moderate, and uninvolved lifestyles. The association analyses were done separately for each choice of product as well as for each attribute-consequence linkage with a non-parametric Mann-Whitney U test. The testing variables were FRL dimensions and the FRL lifestyle factors. In addition, the relation between the attribute-consequence linkages and the demographic variables were analysed. Results from this study showed that the choice of product is sequential, so that consumers first categorize products into groups based on specific criteria like health or convenience. It was attested that the food-related lifestyles function as a script in food choice and that the FRL instrument can be used to predict consumer buying behaviour. Certain lifestyles were associated with the choice of each product category. The actual product choice within a product category then appeared to be a different matter. In addition, this study proposes a modification to the FRL instrument. The positive towards advertising FRL dimension was modified to examine many kinds of information search including the internet, TV, magazines, and other people. This new dimension, which was designated as being open to additional information, proved to be very robust and reliable in finding differences in consumer choice behaviour. Active additional information search was linked to adventurous and snacking food-related lifestyles. The results of this study support the previous knowledge that consumers expect to get many benefits simultaneously when they buy food products. This study brought detailed information about the benefits sought, the combination of benefits differing between products and between respondents. Household economy, pleasure and quality were emphasized with the choice of lettuce. Quality was the most significant benefit in choosing mincemeat, but health related benefits were often evaluated as well. The dominant benefits linked to savoury sauce were household economic benefits, expected pleasurable experiences, and a lift in self-respect. The choice of goat cheese appeared not to be an economic decision, self-respect, pleasure, and quality being included in the choice criteria. In choosing pudding, the respondents considered the well-being of family members, and indulged their family members or themselves.

Exact free-surface flows for shallow-water equations .1. - the incompressible case

A comprehensive exact treatment of free surface flows governed by shallow water equations (in sigma variables) is given. Several new families of exact solutions of the governing PDEs are found and are shown to embed the well-known self-similar or traveling wave solutions which themselves are governed by reduced ODEs. The classes of solutions found here are explicit in contrast to those found earlier in an implicit form. The height of the free surface for each family of solutions is found explicitly. For the traveling or simple wave, the free surface is governed by a nonlinear wave equation, but is arbitrary otherwise. For other types of solutions, the height of the free surface is constant either on lines of constant acceleration or on lines of constant speed; in another case, the free surface is a horizontal plane while the flow underneath is a sine wave. The existence of simple waves on shear flows is analytically proved. The interaction of large amplitude progressive waves with shear flow is also studied.

Molecular interpretation of the linear relationship between the entropy and the enthalpy of activation of charge transfer reactions in polar liquids

The well-known linear relationship (T?S# =??H# +?, where 1 >? > 0,? > 0) between the entropy (?S#) and the enthalpy (?H#) of activation for reactions in polar liquids is investigated by using a molecular theory. An explicit derivation of this linear relation from first principles is presented for an outersphere charge transfer reaction. The derivation offers microscopic interpretation for the quantities? and?. It has also been possible to make connection with and justify the arguments of Bell put forward many years ago.

Water Modeling Study Of The Jet Characteristics In A Continuous-Casting Mold

The jet characteristics and the fluid flow pattern in a continuous slab caster have been studied using a water model. The fluid jet is studied under free fall and submerged discharge conditions. In the latter case, the jet was followed by dye-injection technique and image analyser was used to find out the effect of nozzle parameters on jet-spread angle, jet-discharge angle and the volume entrainment by the jet. All free-fall jets with nozzle port angle zero and upward are found to be spinning. Some of the free-fall jets with downward nozzle-port angle are found to be spinning and rest are smooth. The spinning direction of the jets are found to change with time. The well depth, port diameter and the inner diameter of the nozzle have a clear effect on the free-fall jets with downward port angle. The jet-spread angle is found to be about 17-degrees for smooth jets. The spread angle for spinning jet increases as the nozzle-port angle is increased from downward 25 to upward 15-degrees. The jet-discharge angle is always downward even when the nozzle-discharge ports are angled upward. The extent of volume entrainment by the spinning jet is higher and it increases as the nozzle-port angle is increased from 25 downward to 15-degrees upward.

Sensitivity Enhancement in Solid-State Separated Local Field NMR Experiments by the Use of Adiabatic Cross-Polarization

Measurement of dipolar couplings using separated local field (SLF) NMR experiment is a powerful tool for structural and dynamics studies of oriented molecules such as liquid crystals and membrane proteins in aligned lipid bilayers. Enhancing the sensitivity of such SLF techniques is of significant importance in present-day solid-state NMR methodology. The present study considers the use of adiabatic cross-polarization for this purpose, which is applied for the first time to one of the well-known SLF techniques, namely, polarization inversion spin exchange at the magic angle (PISEMA). The experiments have been carried out on a single crystal of a model peptide, and a dramatic enhancement in signal-to-noise up to 90% has been demonstrated.

LiSr1.65 square 0.35B1.3B ' O-1.7(9) (B = Ti, Zr; B ' = Nb, Ta): New lithium ion conductors based on the perovskite structure

We describe the design and synthesis of new lithium ion conductors with the formula, LiSr(1.65)rectangle(0.35)B(1.3)B'O-1.7(9) (rectangle = vacancy; B = Ti, Zr; B' = Nb, Ta), on the basis of a systematic consideration of the composition-structure-property correlations in the well-known lithium-ion conductor, La-(2/3-x)Li(3x)rectangle((1/3)-2x)TiO3 (I), as well as the perovskite oxides in Li-A-B,B'-O (A = Ca, Sr, Ba; B = Ti, Zr; B' = Nb, Ta) systems. A high lithium-ion conductivity of ca. 0.12 S/cm at 360 degrees C is exhibited by LiSr(1.65)rectangle(0.35)Ti(1.3)Ta(1.7)O(9) (III) and LiSr(1.65)rectangle(0.35)Zr(1.3)Ta(1.7)O(9) (IV), of which the latter containing stable Zr(IV) and Ta(V) oxidation states is likely to be a candidate electrolyte material for all-solid-state lithium battery application. More importantly, we believe the approach described here could be extended to synthesize newer, possibly better, lithium ion conductors.

The Herzog-Vasconcelos conjecture for affine semigroup rings

Let S be a simplicial affine semigroup such that its semigroup ring A = k[S] is Buchsbaum. We prove for such A the Herzog-Vasconcelos conjecture: If the A-module Der(k)A of k-linear derivations of A has finite projective dimension then it is free and hence A is a polynomial ring by the well known graded case of the Zariski-Lipman conjecture.

The steady state nuclear Overhauser effect revisited

The steady state of a two spin system coupled to an isotropic environment and to each other through a dipolar interaction and under irradiation by a monochromatic, circularly polarized radio frequency field is determined ab initio using thermodynamic arguments. This steady state is used to describe the well known nuclear Overhauser effect in liquids. The steady state is also derived from the Solomon-Bloch set of equations used to describe the driven spin. It is shown that in the limit of weak driving, the two solutions coincide. (C) 1999 American Institute of Physics. [S0021-9606(99)71210-9].

Thermodynamic analysis of enzyme catalysed reactions: new insights into the Michaelis-Menten equation

A simple thermodynamic analysis of the well-known Michaelis-Menten equation (MME) of enzyme catalysis is proposed that employs the chemical potential mu to follow the Gibbs free energy changes attending the formation of the enzyme-substrate complex and its turnover to the product. The main conclusion from the above analysis is that low values of the Michaelis constant KM and high values of the turnover number k(cat) are advantageous: this supports a simple algebraic analysis of the MME, although at variance with current thinking. Available data apparently support the above findings. It is argued that transition state stabilisation - rather than substrate distortion or proximity - is the key to enzyme catalysis.

Novel phenomenon of autoacceleration in the free radical oxidative polymerization of vinyl monomers: a thermochemical approach

A unique phenomenon of ‘autoacceleration’ was observed in a free radical polymerization of vinyl monomers and oxygen. Unlike the well known autoacceleration phenomenon in polymerization processes, this unusual phenomenon is not readily conceivable in terms of solution viscosity based reasoning. Surprisingly, we have observed manifestation of this new autoacceleration during free radical oxidative polymerization of some vinyl monomers at low conversions, where generally the polymerization reaction is zero order, the conversion–time plot are linear and viscosity effects are negligible. In the present paper, we interpret the mechanism of this new autoacceleration phenomenon on the basis of reactivity of the propagating radicals in terms of heat of formation data.