Nucleation in supersaturated solutions 3He in 4He at negative pressure.

Depending on the 3He concentration, thermal nucleation in 3-4He supersaturated liquid mixtures at negative pressures may be originated either by bubble or by 3rich drop formation. We have investigated this phenomenon within a density-functional approach, determining the regions in the pressure¿3He-concentration plane where bubbles or drops likely drive the nucleation process. As an illustrative example, we also give the homogeneous nucleation pressure corresponding to 50 and 100 mK temperature.

Investment analysis of chemical projects and development of standerdised mathematical co-relation for cost estimation of pressure vessels in chemical industry

The present study is intended to provide a new scientific approach to the solution of the worlds cost engineering problems encountered in the chemical industries in our nation. The problem is that of cost estimation of equipments especially of pressure vessels when setting up chemical industries .The present study attempts to develop a model for such cost estimation. This in turn is hoped would go a long way to solve this and related problems in forecasting the cost of setting up chemical plants.

Environmental protection pressure groups in kerala: a study on their structure, strategy and role with special reference to industrial pollution

The present study focuses attention on the social phenomenon of environmental protection pressure groups in Kerala. A detailed historical background of environmental protection pressure groups at international and national scenes as background for this study .Emphirical studies of environmental protection pressure groups in Kerala with special reference to industrial pollution is dicussed in detail . The main objective of the study is to identify the factors that make pressure groups succeed or fail in achieving their set objectives.The factors include the structure and strategies of social pressure groups and the support they receive from the environment.

Role of social pressure as a key contributor of materialism and related status consumption

“At resale stores I have seen brand new clothes with original price tag still hanging from the sleeve. Some children have so many toys that they stay frustrated, not knowing which one to pick up for their next amusement. Presumably sensible adults trade in perfectly good cars just to have something shinier and newer. Didn’t us once live productive normal lives, without all these gadgets” [Cunningham (2005)]. During late eighties, nearly forty four percent of the participants, who took part in a consumer survey conducted in the US, responded positively to the question “My closets are filled with still 2 unopened items” [Faber and O’Guinn (1988)]. Reading such excerpts does not greatly surprise us anymore; as such reports have become common now. For many people shopping has moved beyond something that caters to their needs and wants and has become a hobby [Cunningham (2005)], an activity that they engage in to satisfy their hedonistic or pleasure-seeking goals [Ramnathan and Menon(2006), O’Cass and McEween (2004), Faber and O’Guinn (1989)]. Others look at their new possession as something that fills a void in their lives [Belk (1985), Diener et al. (1993)].

Variation in radio refractivity index associated with formation of low - pressure systems

Numerous low - pressure systems form in the Arabian Sea and Bay of Bengal. These low-pressure systems are highly useful in bringing the rainfall over the Indian sub continent. The developments of these systems are accompanied by the reduction in air temperature and an increase in atmospheric humidity. The radio refractivity, which is a function of the atmospheric pressure, temperature and humidity, also changes following the development of these systems. Variation of radio refractive index and its vertical gradient are analysed for many low pressure systems formed over the Arabian Sea and Bay of Bengal. It is found that the atmosphere becomes super refractive associated with the formation of these systems, caused by the increase in humidity and decrease in temperature. The maximum gradient is observed near the surface layers, especially in the lowest 1 km. Super refraction leads to increased radar detection range and extension of radio horizon

Computer-mediated communication and time pressure induce higher cardiovascular responses in the preparatory and execution phases of cooperative tasks

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Caracterización de los pacientes con hemorragia de vías digestivas altas no varicosa atendidos en el Hospital Universitario de la Samaritana, Cundinamarca

La hemorragia de vías digestivas altas (HVDA) es una emergencia frecuente. La etiología más común es la úlcera péptica. La restauración del volumen intravascular y la presión arterial son la prioridad del manejo. La endoscopia (EGD) debe realizarse luego de la reanimación inicial y lograda la estabilización hemodinámica, tratar la lesión subyacente mediante hemostasia. Se realiza un estudio en un hospital de referencia de tercer nivel, Cundinamarca, Colombia Materiales y métodos: Estudio descriptivo retrospectivo, datos obtenidos de la historia clínica electrónica de pacientes adultos que consultaron por urgencias en el Hospital Universitario de la Samaritana (HUS) por HVDA, diagnosticada por hematemesis, melenas, hematoquezia y/o anemia; a quienes se les realizó EGD durante abril del 2010 - abril del 2011. Resultados: Se atendieron 385 pacientes en el período de estudio, 100 fueron excluidos debido a hemorragia secundaria a várices esofágicas, historia incompleta y hemorragia digestiva baja, para un total de 285 pacientes analizados. El 69.1% eran mayores de 60 años. El 73.3% presentaba hipertensión arterial, el 55.1% reportaba ingesta de Anti-inflamatorios no esteroideos (AINES) y Aspirina (ASA). El 19.6% reportaba episodios de sangrado previos y 17.9% presentó inestabilidad hemodinámica. Sesenta y tres pacientes (22,1%) requirieron hemostasia endoscópica, treinta y dos (11.2%) presentaron resangrado. La mortalidad reportada fue del 13.1%, del cual 55.3% correspondía a hombres. Discusión: La mayoría de la población atendida en el HUS por HVDA son adultos mayores de 60 años. La úlcera péptica, continúa siendo el diagnóstico más frecuente asociado al uso de AINES y ASA.

Sources of perceived sociocultural pressure on physical self-concept

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Gas collisions and pressure quenching of the photoluminescence of silicon nanopowder grown by plasma-enhanced chemical vapor deposition

The quenching of the photoluminescence of Si nanopowder grown by plasma-enhanced chemical vapor deposition due to pressure was measured for various gases ( H2, O2, N2, He, Ne, Ar, and Kr) and at different temperatures. The characteristic pressure, P0, of the general dependence I(P)=I0exp(-P/P0) is gas and temperature dependent. However, when the number of gas collisions is taken as the variable instead of pressure, then the quenching is the same within a gas family (mono- or diatomic) and it is temperature independent. So it is concluded that the effect depends on the number of gas collisions irrespective of the nature of the gas or its temperature

Pressure-jump-induced kinetics reveals a hydration dependent folding/unfolding mechanism of ribonuclease A

Pressure-jump (p-jump)-induced relaxation kinetics was used to explore the energy landscape of protein folding/unfolding of Y115W, a fluorescent variant of ribonuclease A. Pressure-jumps of 40MPa amplitude (5ms dead-time) were conducted both to higher (unfolding) and to lower (folding) pressure, in the range from 100 to 500MPa, between 30 and 50°C. Significant deviations from the expected symmetrical protein relaxation kinetics were observed. Whereas downward p-jumps resulted always in single exponential kinetics, the kinetics induced by upward p-jumps were biphasic in the low pressure range and monophasic at higher pressures. The relative amplitude of the slow phase decreased as a function of both pressure and temperature. At 50°C, only the fast phase remained. These results can be interpreted within the framework of a two-dimensional energy surface containing a pressure- and temperature-dependent barrier between two unfolded states differing in the isomeric state of the Asn-113–Pro-114 bond. Analysis of the activation volume of the fast kinetic phase revealed a temperature-dependent shift of the unfolding transition state to a larger volume. The observed compensation of this effect by glycerol offers an explanation for its protein stabilizing effect

General relationships between pressure, weight, and mass of a hydrostatic fluid

In curved geometries the hydrostatic pressure in a fluid does not equal the weight per unit area of the fluid above it. General weight–pressure and mass–pressure relationships for hydrostatic fluids in any geometry are derived. As an example of the mass–pressure relationship, we find a geometric reduction in surface pressure as large as 5 mbar on Earth and 39 mbar on Titan. We also present a thermodynamic interpretation of the geometric correction which, as a corollary, provides an independent proof of the hydrostatic relationship for general geometries.

Deforming glassy polystyrene: Influence of pressure, thermal history, and deformation mode on yielding and hardening

The toughness of a polymer glass is determined by the interplay of yielding, strain softening, and strain hardening. Molecular-dynamics simulations of a typical polymer glass, atactic polystyrene, under the influence of active deformation have been carried out to enlighten these processes. It is observed that the dominant interaction for the yield peak is of interchain nature and for the strain hardening of intrachain nature. A connection is made with the microscopic cage-to-cage motion. It is found that the deformation does not lead to complete erasure of the thermal history but that differences persist at large length scales. Also we find that the strain-hardening modulus increases with increasing external pressure. This new observation cannot be explained by current theories such as the one based on the entanglement picture and the inclusion of this effect will lead to an improvement in constitutive modeling.

Temperature- and Pressure-induced Proton Transfer in the 1:1 Adduct Formed between Squaric Acid and 4,4 '-Bipyridine

We have applied a combination of spectroscopic and diffraction methods to study the adduct formed between squaric acid and bypridine, which has been postulated to exhibit proton transfer associated with a single-crystal to single-crystal phase transition at ca. 450 K. A combination of X-ray single-crystal and very-high flux powder neutron diffraction data confirmed that a proton does transfer from the acid to the base in the high-temperature form. Powder X-ray diffraction measurements demonstrated that the transition was reversible but that a significant kinetic energy barrier must be overcome to revert to the original structure. Computational modeling is consistent with these results. Modeling also revealed that, while the proton transfer event would be strongly discouraged in the gas phase, it occurs in the solid state due to the increase in charge state of the molecular ions and their arrangement inside the lattice. The color change is attributed to a narrowing of the squaric acid to bipyridine charge-transfer energy gap. Finally, evidence for the possible existence of two further phases at high pressure is also presented.