Grid computing for electromagnetics: a beginner's guide with applications

The demand for computing power in computational electromagnetics (CEM) is continuously increasing. Meanwhile, cooperative engineering is becoming more and more present in daily research and development workflows. Projects are often developed by teams, which interact remotely, and need tighter and tighter connectivity. Grid computing (GC), from the perspective of progress in computer networks, seems a promising way to satisfy both the need of high-performance computing platforms, and the requirements for effective cooperative computing. In this paper, researchers involved in CEM are introduced to grid computing, and to the use of grid computing for CEM. Two real applications are proposed, with a critical discussion on potential benefits and drawbacks with respect to alternative strategies.     

Percutaneous blind needle biopsy versus combined laparoscopic excisional and guided needle biopsy in the diagnosis of liver disorders in pediatric patients

A special interest, both in scientific publications and in the mass media, is recently emerged about the use of hormone replacement therapy (HRT) in post-menopausal women. Beside, in fact, the specific indication for the relief of menopausal symptoms, hypotheses are debated about a possible role of HRT in the reduction of risk of osteoporosis and cardiovascular diseases, and in the increased risk of breast cancer. This situation emphasizes the need for assessing the benefit/risk profile for HRT in order to ensure that strategies of proven clinical effectiveness, based on large randomized clinical trials, will be adopted in the population.     

Transient liquid phase bonding of HfC-based ceramics

Transient liquid phase (TLP) bonding enables joining at lower temperatures than traditional bonding techniques and preserves the potential for high-temperature applications, making it particularly attractive for joining ultra-high-temperature ceramics (UHTCs) such as carbides and borides. The feasibility of a TLP joint between “pure” carbides has been recently demonstrated. The present study examines the interactions that occur between undoped HfC or MoSi₂-doped HfC and a Ni/Nb/Ni multilayer interlayer during TLP bonding. Bonding is performed at 1400 °C for 30 min in a high-vacuum furnace. SEM–EDS characterization shows that the reaction layer formed at the interlayer/ceramic interface contains mixed carbides and depending upon the ceramic, Ni–Nb–Hf, or Ni–Nb–Hf–Si, or Ni–Nb–Si alloys. Nanoindentation tests traversing the reaction layer between the bulk ceramic and Nb foil midplane also show a clear transition zone across which the indentation modulus and hardness vary. Crack-free joints have been obtained with undoped HfC. The addition of 5 vol% MoSi₂ introduces small (<5 μm long) isolated cracks within the reaction layer, whereas with 15 vol% MoSi₂ added, cracking was pervasive within the reaction layer. When the reaction layer exceeds a critical thickness, as in the case of the bond obtained with HfC doped with 15 vol% MoSi₂, residual stresses become sufficiently large to cause extensive cracking and bond failure. The results suggest a need to characterize and balance the positive role of additives on sintering with the potentially deleterious role they may have on joining.     

Adaptive response: modelling and experimental studies

Adaptive response (AR) is a term that has been generally accepted to describe the ability of a low 'priming' radiation dose to decrease the cell response to a subsequent higher 'challenging' dose. The main proposed mechanisms to explain AR are: increased efficiency of DNA repair and induction of antioxidant enzymes. A model that considers a modulation of the efficiency of DNA repair activity and of the level of antioxidant enzymes, starting from the framework of a lethal-potentially lethal (LPL) model is proposed. The LPL model has been extended with the inclusion of the dynamic variables representing the efficiency of repair, the levels of radiation induced radicals and of antioxidant enzymes. The model used here is able to describe the protective effect of a priming dose. Moreover, in agreement with the data in the literature, the simulations show that the AR happens in given priming dose and priming dose-rate ranges only, and requires at least 4 h to develop. In order to get more insights into the role of cell-cell communication as factors affecting the AR, experimental studies were planned using sparse or confluent AG1522 cell monolayer. The results obtained after gamma irradiation suggest that cell density is a crucial factor for observing an AR.     

Experimental features affecting the transparency of YAG ceramics

This article focuses on the importance of the ceramic production process for the final transparency and overall optical quality of materials to be used as laser hosts. YAG-based ceramics are prepared starting from commercial powders. The materials are prepared by reactive sintering in a clean atmosphere and under high vacuum. Nd or Yb are selected as active elements as the more appropriate for high energy and high peak power lasers. The powder type and treatment and the solvent removal technique are described in detail as well as the experimental conditions adopted during shaping. The influence of the pre-sintering and sintering cycles on the reaction among the involved oxides and on the microstructure after sintering is shown. The optical characterization is also reported.     

Experimental investigation on shear behaviour of riveted connections in steel structures

The results of an experimental study based on lap-shear tests on riveted connections are presented in this paper. Experimental specimens were manufactured with materials and techniques used in aged metal structures and different dimensions and configurations were considered. The results of the experimental investigation allowed the influence of various parameters on the response of the connections to be assessed, such as load eccentricity, variation in net area, plate width and number of rivets. The experimental results and predicted shear strengths were compared in order to evaluate the reliability of the provisions of EN 1993:1-8. On the basis of the results obtained, modifications are proposed to the design equations given by EN 1993:1-8 for the rivet shear strength and the ultimate resistance of the net cross-section.     

Cellular receptors for sex steroids in human pituitary adenomas

Cellular receptors for sex steroids (SSRs) were studied in an unselected series of 55 human pituitary tumors. Cytosolic receptors for estrogen (ERcs) and progesterone (PgRcs) were determined in all cases and cytosolic androgen receptors (ARcs) in 47 cases. Nuclear receptors (ERns, PgRns, ARns) were also studied in 33 cases. ERs and PgRs were determined by an ELISA and ARs by [3H]methyltrienolone binding. Where both cytosolic and nuclear receptors were studied (n = 33), ERs, PgRs and ARs were found in at least one subcellular fraction in 66.7, 60.6 and 81.8% of cases respectively, ERs and ARs being mainly recovered from the cytosol and PgRs from the nucleus. No linear correlation was found between pre-operative plasma steroid hormones and their specific cellular receptors. Nonetheless, the differential expression of SSRs according to sex and gonadal status at the time of surgery strongly supports their regulation by the steroid environment in vivo: PgRcs were more frequent in tumors found in women (41.4 vs 15.4%, P < 0.05), whereas a high expression of ERcs and ARcs (> 15 fmol/mg protein) was more common in tumors found in men (34.5 vs 10.3%, P < 0.05 and 54.5 vs 24.0% respectively). PgRs were positively correlated with ERns, indicating the possibility of estrogen priming of their expression, and negatively correlated with ARs in nuclear fractions. SSRs appeared to be widely distributed among pituitary tumors, although, compared with other hormone-secreting groups, prolactinomas displayed a higher ERc expression (34.8 +/- 11.3 vs 4.8 +/- 5.1 fmol/mg protein, P = 0.007) and gonadotroph cell adenomas lower ARc values (1.3 +/- 0.8 vs 38.2 +/- 10.6 fmol/mg protein, P = 0.048). Microadenomas were characterized by a higher PgR expression than macroadenomas, whereas hemorrhagic (macro)adenomas were characterized by a high ER expression (> 90%). The present results indicate that most pituitary tumors are targets for sex steroids, SSR expression being partially triggered by the steroid environment itself. Possible physiopathological and therapeutic implications of these findings are discussed.     

Epidemiological data on burn injuries in Angola: a retrospective study of 7230 patients

This study describes the work carried out at the Burn Unit of the Neves Bendinha Hospital, Luanuda, Angola, during the 3-year period July 1991 to June 1994. During this period we admitted 2569 burned patients to our burn unit, and 4661 were treated on an outpatient basis. The data from the patients were analysed to indicate the distribution according to age, sex, TBSA, cause of the lesion and mortality. Our study gives some epidemiological data on burns in an undeveloped country undergoing a war, outlining the specific problems compared to the reality in civilized countries.     

Inhibition of diabetic nephropathy by a GH antagonist: a molecular analysis

Streptozotocin-treated C57B1/SJL mice developed glomerular hypertrophy and light microscopic lesions mimicking human diabetic glomerulosclerosis. In contrast, there were no glomerular hypertrophy and lesions in diabetic mice transgenic (TG) for a mutated growth hormone (bGH-G119K) that competes with native endogenous GH and results in dwarfism. We examined the molecular events underlying these findings. The non-transgenic (non-TG) diabetic mouse glomeruli had an increase in mRNA coding for alpha 1IV collagen, laminin B1, TGF-beta 1, 72 kDa collagenase, and TIMP-3. In contrast, glomerular type IV collagen and laminin B1 mRNA levels were normal in diabetic TG dwarf mice. However, the 72 kDa gelatinase, TIMP-3, and TGF-beta 1 mRNAs were elevated in the diabetic dwarfs. Type IV collagen and laminin accumulated in the glomeruli of diabetic non-TG, but not of diabetic dwarf mice, by immunofluorescence microscopy, confirming the mRNA data. GH binding protein mRNA levels were comparable in glomeruli from dwarf and non-TG mice, both diabetic and non-diabetic. We did not detect GH receptor mRNA in glomeruli. These data suggest that diabetic glomerulosclerosis is associated with an increase in type IV collagen and laminin synthesis, and that these changes do not occur in mice transgenic for bGH119K, a functional antagonist of GH. The increase of 72 kDa gelatinase, TIMP-3 and TGF-beta 1 mRNAs, independent of GH, suggested that these changes induced by hyperglycemia were not sufficient for the induction of glomerulosclerosis.