Calorimetric measurements on some undercooled metals and alloys

Undercooling was achieved directly in the cell of a high temperature calorimeter (Setaram HTDSC) for Ni, Fe, Cu, Pd and several alloys, using cooling rates between 1 and 15 K min⁻¹. The samples were immersed in alumina powder inside a standard alumina crucible under flowing helium. Ag, Au and Al were not undercooled significantly. The reproducibility of the measurements was within 1.5%. The heat of solidification of Ni at an undercooling of ΔT = 220 K was −17.5 ± 0.2 kJ mol⁻¹, which is the same absolute value of the heat of fusion at the equilibrium melting point T_m. This implies that the specific heat of the undercooled liquid is very close to that of the crystalline solid in this temperature range. Fe appears to display a similar behavior at ΔT = 220 K. The difference between the heat of fusion at T_m and the heat of solidification at an average value of ΔT = 95 K is significant for a Pd_77.5Cu₆Si_16.5 glass-forming alloy. From these data, we calculated an average specific heat difference between the liquid and crystal phases of 7 ± 5 J mol⁻¹ K⁻¹. The enthalpy data for Pd₈₂Si₁₈ comply with those of the ternary Pd---Cu---Si.     

Pharmacological characterization of nociceptin receptor: an in vitro study

Pancreatic cancer is difficult to treat, even for tumours localized to the pancreas. Photodynamic therapy (PDT) is a non-thermal technique for producing localized tissue necrosis with light after prior administration of a photosensitizing drug and it could have a role in the local treatment of these cancers. We studied PDT in a transplanted cancer in the hamster pancreas using the photosensitizer mTHPC (meta-tetrahydroxyphenylchlorin). Fluorescence microscopy showed maximum levels of mTHPC in normal pancreas 2-4 days after sensitization and in tumour at 4-5 days. For PDT, animals were given 0.1 or 0.3 mg kg(-1) mTHPC and the tumour was treated at laparotomy 2 or 4 days later with red light (50 J at 650 nm, continuous or fractionated) delivered via a single fibre touching the tumour surface. The maximum zone of tumour necrosis (seen 3 days after PDT) was 8.7 mm in diameter with continuous irradiation, increasing to 12.4 mm with light fractionation (four equal fractions with 3 min between fractions). The main complication was sealed duodenal perforation, seen in 3 of 16 animals, probably due to inadequate shielding of the duodenum from the light. The duodenal problems seen in hamsters are unlikely to cause trouble in the much thicker human duodenum. PDT tumour necrosis in this animal model has now been shown with a range of photosensitizers, but mTHPC is attractive as it is likely to produce the largest volumes of necrosis around each treatment point with short light exposure times. This technique could have a role in the treatment of localized cancers of the pancreas in patients unsuitable for surgery and can now be considered for preliminary clinical trials.     

On the effect of the local overall interaction on the postbuckling of uniformly compressed channels

On the basis of the general theory of elastic stability due to Koiter, postbuckling analysis of simply supported channels under uniform compression is performed. Attention is essentially focused on local/eularian and local/flexural-torsional simultaneous bucklin modes interaction. The column is treated as a plate assemblage. Linearized expressions for the displacement field are employed while assuming strain-displacements relationships that are linear for the curvatures and up to second order terms for the in-plane strains. The total potential energy is hence written up to third order terms in order to investigate asymmetric buckling phenomena. A discrete model is developed through an automatic procedure of algebraic manipulation, and an extensive parametric analysis is performed. After determining the range of geometric parameters which characterize different types of interaction, it is found that in the postbuckling range the local/eulerian interaction is more dangerous than the local/flexural-torsional one, due to the column higher imperfection sensitivity.     

Close relationships and adjustments to a life crisis: The case of breast cancer.

When life crises occur significant others are thought to help alleviate distress and resolve practical problems. Yet life crises may overwhelm significant others, eroding their ability to provide effective support. The accuracy of these contrasting accounts of relationship functioning was evaluated in a study of 102 breast cancer patients and their significant others, interviewed at 4 and 10 months after diagnosis. Results largely confirmed the negative account of relationship functioning. Although significant others provided support in response to patients' physical impairment, they withdrew support in response to patients' emotional distress. Moreover, support from significant others did not alleviate patients' distress or promote physical recovery. These results reveal limits to the effectiveness of close relationships in times of severe stress. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

I3D: a new dataset for testing denoising and demosaicing algorithms

Multimedia Tools and Applications - In this paper we present a dataset of images to test the performance of image processing algorithms, in particular demosaicing and denoising methods. Despite the...     

On the Consequences of the Adoption of the Zaremba–Jaumann Objective Stress Rate in FEM Codes

This paper deals with a particular issue of computational mechanics in main FEM codes nowadays available, i.e. the outcomes of implementations of large strain constitutive models based on the adoption of so-called objective stress rates, in order to satisfy objectivity requirements. The point here is that of directly inquiring whether well-known incoherencies due to the adoption of the Zaremba–Jaumann objective stress rate may manifest themselves when the most used elastic and elastoplastic constitutive models are adopted. The present investigation aims at providing a comprehensive review of the theoretical aspects and at developing an informed knowledge to final users of FEM codes, in terms of exposing which constitutive models and FEM implementations may be affected by Zaremba–Jaumann objective stress rate induced incoherencies. Towards this end, local FEM simple shear tests are explored and clearly show that kinematic cases characterized by a non zero spin may be heavily affected by oscillatory incoherencies, which arise for expected cases, i.e. Cauchy stress responses, but also for other less expected cases, i.e. strain responses, whether they are total, elastic or plastic. Beyond local tests, structural simple shear tests are also performed and show as well that oscillatory incoherencies found in local simple shear tests may heavily influence the overall structural outcomes. A non-secondary target of the paper is that of reviewing the relevant scientific and technical literature about objective stress rates, by critically analyzing correlated issues and proposed solutions, considering scientific contributions spanning over a century, keeping specific attention to the treatment of the Zaremba–Jaumann objective stress rate and to the possible flaws related to its adoption.     

A fuzzy set approach to Retinex spray sampling

The color sensation at a point, for the Human Visual System (HVS), derives not only from the color stimulus at that point, but also from the relative spatial arrangement of the stimuli in the image. Based on this observation, the Retinex algorithm, an early and widely studied model of the HVS, determines the output – for each chromatic channel – by rescaling the input intensity of a pixel w.r.t. a reference white level, computed by sampling the brightest points in the neighborhood of the target pixel. In this work, we argue that several elements, inherent to the above observation, can benefit from a fuzzy formalization. We show that the adoption of the fuzzy formalism allows to better encode the mutual influence of pixels. Overall, the fuzzy formalization can provide a general framework for designing and tuning image enhancement algorithms inspired by the HVS. We demonstrate its use by the construction of a fuzzy version of the point-sampling algorithm Random Spray Retinex (RSR). Using RSR as a guide, we build a more efficient algorithm, based on the fact that each spray (a set of sampled points used in RSR to determine the reference white of a specific target) can be assumed to belong to some degree to all the target pixels of the image, provided that a suitable membership function is defined. The features of this alternative formalization of RSR are discussed here, using synthetic and natural test images.