Al–Ti powder produced through mechanical alloying for different times

A powder mixture of aluminum, 10 wt% titanium, and 1.5 wt% of a wax acting as process control agent (PCA), has been attrition-milled for 2–20 h. Titanium powder had been previously ground to a lower particle size to make it similar to the as-received aluminum particle size. The overall aim of this work was to achieve a metastable titanium solution in the aluminum matrix. Changes with milling time of particle size and shape, microstructure, hardness and other powder characteristics have been studied. Given the used experimental-conditions, a process time of 10 h has been selected for the mechanical alloying (MA) of Al–10Ti powder, attaining a compromise between uniform microstructure development and a not so long processing time. At this milling time aluminum dissolves about 9 wt% Ti, increasing its Vickers microhardness (202 VH₂₀) more than 10 times with reference to the starting Al powder (20 VH₂₀). Milled particle size is smaller than the starting one (17 vs. 44 μm). Increasing milling for longer times, up to 20 h, does not produce important changes in powders structure.     

Demodulation of a single interferogram by use of a two-dimensional regularized phase-tracking technique

We present a two-dimensional regularized phase-tracking technique that is capable of demodulating a single fringe pattern with either open or closed fringes. The proposed regularized phase-tracking system gives the detected phase continuously so that no further unwrapping is needed over the detected phase.     

The Effect of 45° Rolling Process on the Mechanical Properties of P/M Rhenium

A novel processing technique which utilizes the 45° rolling mode is introduced. An optimum processing method of light rolling (10-12% reduction in thickness) along the 45° direction, followed by intermittent annealing (1650°C / 30 min. in H₂ atmosphere) was carried out. The partial reduction and intermittent annealing were repeated until an 82.9% reduction was achieved with a tensile strength of 2388 MPa (346.6 Ksi) and 3.3% elongation. Additional experiments were performed to test the feasibility of increasing the percentage of reduction in thickness in cold rolling from the conventional 10-15% to 20-55% along the 45° direction. Although extensive microcracking occurred, intermediate strengths were achieved and ductility was retained. This processing technique has the potential of producing ultra high strength, very thin sheets, which are vital for space nuclear power applications and missile guidance systems.     

Phosphatidylinositol 3-kinase is required for CD28 but not CD3 regulation of the TEC family tyrosine kinase EMT/ITK/TSK: functional and physical interaction of EMT with phosphatidylinositol 3-kinase

Ligation of the TCR or CD28 induces activation of phosphatidylinositol 3-kinase (PI3K), the TEC family protein tyrosine kinase, EMT/ITK/TSK (EMT), and the SRC family tyrosine kinase, LCK. LCK is required for the activation and phosphorylation of EMT induced by ligation of the TCR or CD28 placing LCK upstream of EMT in T cell signaling cascades. We report herein that inhibition of PI3K activity with the specific inhibitors LY294002 and wortmannin markedly decreased EMT activation induced by CD28 cross-linking but not by CD3 cross-linking. Further, inhibition of PI3K markedly decreased EMT in vitro autokinase activity induced by activated LCK. In contrast, PI3K inhibitors did not alter CD28 or CD3 cross-linking or LCK-induced EMT phosphorylation. Consistent with the requirement of PI3K activity for CD28 but not CD3-induced stimulation of the EMT in vitro autokinase activity, a small but significant portion of cellular EMT associates with PI3K following CD28 cross-linking but not following CD3 cross-linking. CD28-induced association of EMT with PI3K also requires functional expression of LCK. Fusion proteins containing the SRC homology 2 domain of EMT interact with PI3K or a PI3K-associated molecule in a tyrosine phosphorylation-dependent manner. Taken together, the data suggest that EMT is differentially regulated and recruited to different signaling complexes following ligation of CD28 or the TCR complex, perhaps contributing to the disparate roles that EMT appears to play downstream of CD28 and the TCR.     

Eosinophilic lung disease associated with Candida albicans allergy

PURPOSE: We evaluate the effect of the provision of postgraduate educational material on improving practitioner knowledge base during a 3-year period. MATERIALS AND METHODS: A total of 210 urologists were provided 67 monographs in a 2-year period. They were given a pretest before and posttest 1 year after receipt of all monographs. RESULTS: There was significant improvement in posttest scores for the group as a whole. Improvement correlated with years post-training and number of monographs read. Multivariate analysis revealed the number of monographs read was the only independent predictor of outcome. CONCLUSIONS: Although the improvement in test scores was significant and did correlate with the postgraduate educational material read, it was modest. This finding raises significant concerns about the usefulness of this format for graduate medical education.     

Influence of risk factors and pharmacological treatment on mortality in patients with essential hypertension

BACKGROUND: The V JNC consensus stated that although new antihypertensive agents, such as angiotensin converting enzyme inhibitors and calcium channel blockers, are considered safer drugs, there is no firm evidence from large controlled trials that these drugs are associated with a lower cardiovascular mortality. AIM: To study the association between cardiovascular risk factors, blood pressure levels, pharmacological treatment and mortality in a group of hypertensive patients followed at an hypertension outpatient clinic. PATIENTS AND METHODS: Patients with essential hypertension were treated with different antihypertensive medications, according to physicians criteria, and controlled until death or loss from follow up. Causes of death were obtained from hospital records and death certificates. Survival was analyzed using life tables, comparisons between groups of patients were done using chi square or a Cox's proportional hazards model. RESULTS: Three hundred thirty-nine hypertensive patients aged 33 to 80 years old were followed for a mean period of 9.8 +/- 4.9 years. Eighty-six were treated with beta blockers, 64 with diuretics, 133 with calcium antagonists and 56 with ACE inhibitors. Blood pressure dropped similarly with all medications. During follow up, 79 patients died. Life table analysis showed that patients with a history of angina, diabetes or myocardial infarction had higher mortality rates. Similarly, patients treated with beta blockers and diuretics had higher mortality than patients treated with calcium antagonists or angiotensin converting enzyme inhibitors. The proportional hazards model showed that the effect of treatment modality persisted after correction for the other risk factors for mortality. CONCLUSIONS: In this series of hypertensive patients, those treated with beta blockers or diuretics had higher mortality rates than those receiving calcium channel antagonists or angiotensin converting enzyme inhibitors.     

Diagnostic focus on the child with myoclonic seizures in isolation or associated with other types of seizures

Myoclonus may be observed in children with mild or severe epileptic syndromes. Both types are seen at characteristic ages, together with other factors: aetiology, family history, hereditary pattern, effect on psychomotor development and EEG-EMG findings. In children with progressive or degenerative encephalopathies and myoclonus, better known as progressive myoclonic epilepsy, there are also specific clinical data, together with biological and genetic markers which permit identification. The most specific clinical characteristics of each of these clinical pictures are described, as are the complementary tests which permit confirmation of these diagnoses.     

Morphogenesis of the Drosophila fusome and its implications for oocyte specification

The Drosophila oocyte develops within a cyst of 16 germline cells interconnected by ring canals. Polarized, microtubule-based transport of unknown determinants is required for oocyte formation, but whether polarity is established during or after cyst formation is not clear. We have analyzed how polarity develops in stem cells and dividing cysts by following the growth of the fusome, a vesiculated cytoplasmic organelle. Our studies show that the fusome grows by a regular, polarized process throughout the stem cell and cyst cell cycles. Each polarization cycle begins in mitosis, when the fusome segregates to a single daughter cell of each pair. Following mitosis, a 'plug' of fusomal material forms in each nascent ring canal and gradually fuses with the pre-existing fusome. In stem cells, the ring canal is transient and closes down after the fusome is partitioned through it. In dividing cysts, as the fusome plugs move toward the pre-existing fusome, their associated ring canals also move, changing the geometry of the cyst. At the end of each cycle of cyst growth, the fusome remains asymmetrically distributed within the cyst; one of the two cells with four ring canals retains a bigger piece of fusome than any other cell, including the other cell with four ring canals. Based on these observations, we argue that the oocyte is specified at the first cyst division.     

Review of analytical models for the study of highly doped regionsof silicon devices

Several analytical models developed to study the transport of minority carriers in heavily doped emitter regions of silicon devices are reviewed and compared. To calculate the emitter recombination current, special emphasis is placed on the models of J. Del Alamo and R.M. Swanson (ibid, vol.31, no.12, p.1878-88, 1984) and of J.S. Park, A. Neugroschel, and F. Lindholm (ibid, vol.33, no.2, p.240-8, 1986), which are shown to contain other previous models. For solar cells and photodiodes, the quantum collection efficiency and the photogenerated current are also to be calculated; the models developed by M.A. Green and A.W. Blakers (ibid, vol.30, no.10, p.1360-5, 1983) and by J. Del Alamo and Swanson (Proc. 17th IEEE Photovoltai Specialists Conf., p.1303-8, 1984) for that purpose is described and extended. The approximate analytical solutions are shown to constitute upper and lower bounds on the exact solution. The accuracy and range of applicability of these bounds are discussed     

Region growing with pulse-coupled neural networks: an alternative to seeded region growing.

The seeded region growing (SRG) algorithm is a fast robust parameter-free method for segmenting intensity images given initial seed locations for each region. The requirement of predetermined seeds means that the model cannot operate fully autonomously. In this paper, we demonstrate a novel region growing variant of the pulse-coupled neural network (PCNN), which offers comparable performance to the SRG and is able to generate seed locations internally, opening the way to fully autonomous operation.