Analysis of strengthening in AA6111 during the early stages of aging: Atom probe tomography and yield stress modelling

In this work, a series of aging treatments has been conducted on AA6111 alloy samples for various times at ambient temperature (so-called natural aging) and at temperatures between 60 and 180 °C (artificially aged). The time at artificial ageing was chosen such that samples with approximately the same yield stress were produced. The microstructures of these alloy samples have been carefully characterized using atom probe tomography together with advanced cluster-finding techniques in order to obtain quantitative information about the changes in distribution of both the solute clusters and early-stage precipitates that are formed. The size distribution of clusters has been mapped onto the glide plane and then the stress necessary for a dislocation to pass through the range of obstacles has been estimated using an areal glide model where the dislocation–obstacle interaction strength has been assumed to be related to the obstacle size on the glide plane. It is demonstrated that the contribution of cluster strengthening during artificial aging at higher temperatures is dominated by the high number density of small clusters (Guinier radius <1 nm), whereas the situation during room temperature natural aging is more complex.     

Bone morphogenetic protein 6 promotes FSH receptor and anti-Müllerian hormone mRNA expression in granulosa cells from hen prehierarchal follicles

A growing body of literature provides evidence of a prominent role for bone morphogenetic proteins (BMPs) in regulating various stages of ovarian follicle development. Several actions for BMP6 have been previously reported in the hen ovary, yet only within postselection (preovulatory) follicles. The initial hypothesis tested herein is that BMP6 increases FSH receptor (FSHR) mRNA expression within the granulosa layer of prehierarchal (6-8?mm) follicles (6-8 GC). BMP6 mRNA is expressed at higher levels within undifferentiated (1-8?mm) follicles compared with selected (≥9?mm) follicles. Recombinant human (rh) BMP6 initiates SMAD1, 5, 8 signaling in cultured 6-8?GC and promotes FSHR mRNA expression in a dose-related fashion. In addition, a 21?h preculture with rhBMP6 followed by a 3?h challenge with FSH increases cAMP accumulation, STAR (StAR) expression, and progesterone production. Interestingly, rhBMP6 also increases expression of anti-Müllerian hormone (AMH) mRNA in cultured 6-8?GC. This related BMP family member has previously been implicated in negatively regulating FSH responsiveness during follicle development. Considering these data, we propose that among the paracrine and/or autocrine actions of BMP6 within prehierarchal follicles is the maintenance of both FSHR and AMH mRNA expression. We predict that before follicle selection, one action of AMH within granulosa cells from 6 to 8?mm follicles is to help suppress FSHR signaling and prevent premature granulosa cell differentiation. At the time of selection, we speculate that the yet undefined signal directly responsible for selection initiates FSH responsiveness. As a result, FSH signaling suppresses AMH expression and initiates the differentiation of granulosa within the selected follicle.     

Trauma in pregnancy: the role of interpersonal violence

OBJECTIVE: Our purpose was to determine what role interpersonal violence as intentional injury plays in the pregnant trauma victim. STUDY DESIGN: We performed a retrospective review of medical records. RESULTS: During a 9-year period in a single university medical and trauma center, 203 pregnant women were treated for a physically traumatic event. Sixty-four women (31.5%) were victims of intentional injury, in most cases by the husband or boyfriend. Although the mean Injury Severity Score was higher in women with fetal death than in women with successful pregnancy outcomes (7.25 vs 1.74, respectively; p < 0.01), 5 of the 8 women with fetal losses incurred these despite an apparent absence of physical injury (maternal Injury Severity Score = 0). CONCLUSIONS: Interpersonal violence during pregnancy is a frequent and increasingly common cause of maternal injury. The inconsistent relationship between Injury Severity Score and serious fetal injury or death is underscored by the loss of 5 fetuses despite an Injury Severity Score of 0.     

The influence of codopants and fabrication conditions on germaniumdefects in optical fiber preforms

The GeE' defect concentration in MCVD germanosilicate preforms, as measured by cathodoluminescence profiles, is dramatically reduced by the addition of phosphorus as a codopant. The GeE' concentration is increased by using higher deposition temperatures and oxygen deficient conditions     

Geometry and Topology of Superfluid Turbulence

Superfluid turbulence consists of a very complex, apparently disordered, tangle of quantized vortex filaments. Until now it has been usual to characterize the vortex tangle mainly in terms of its density (length of vortex line per unit volume). The vortex line density is related to energy, so it has a simple physical interpretation; moreover, it is directly measured in the experiments and is easily computed in the numerical simulations. Unfortunately, the vortex line density does not describe the intrinsic disorder, coiling and linking which occurs within the turbulent vortex tangle due to the combined action of the Biot–Savart law and vortex reconnections. Using ideas borrowed from modern geometry and knot theory, firstly we introduce new measures to describe the geometrical and topological complexity of superfluid turbulence. Secondly, we test these measures on a model problem--the growth of a patch of quantized vorticity--and compare the rate of growth of complexity against the rate of growth of energy and length. Finally, we determine how vortex reconnections depend on the vortex line density.     

Pulmonary emphysema decreases hamster skeletal muscle oxidative enzyme capacity

Skeletal muscle oxidative enzyme capacity is impaired in patients suffering from emphysema and chronic obstructive pulmonary disease. This effect may result as a consequence of the physiological derangements because of the emphysema condition or, alternatively, as a consequence of the reduced physical activity level in these patients. To explore this issue, citrate synthase (CS) activity was measured in selected hindlimb muscles and the diaphragm of Syrian Golden hamsters 6 mo after intratracheal instillation of either saline (Con, n = 7) or elastase [emphysema (Emp); 25 units/100 g body weight, n = 8]. Activity level was monitored, and no difference between groups was found. Excised lung volume increased with emphysema (Con, 1.5 +/- 0.3 g; Emp, 3.0 +/- 0.3 g, P < 0.002). Emphysema significantly reduced CS activity in the gastrocnemius (Con, 45.1 +/- 2.0; Emp, 39.2 +/- 0.8 micromol . min-1 . g wet wt-1, P < 0.05) and vastus lateralis (Con, 48.5 +/- 1.5; Emp, 44.9 +/- 0.8 micromol . min-1 . g wet wt-1, P < 0.05) but not in the plantaris (Con, 47.4 +/- 3.9; Emp, 48.0 +/- 2.1 micromol . min-1 . g wet wt-1, P < 0.05) muscle. In contrast, CS activity increased in the costal (Con, 61.1 +/- 1.8; Emp, 65.1 +/- 1.5 micromol . min-1 . g wet wt-1, P < 0.05) and crural (Con, 58.5 +/- 2.0; Emp, 65.7 +/- 2.2 micromol . min-1 . g wet wt-1, P < 0.05) regions of the diaphragm. These data indicate that emphysema per se can induce decrements in the oxidative capacity of certain nonventilatory skeletal muscles that may contribute to exercise limitations in the emphysematous patient.     

Guidance on ill health retirement

Doctors are increasingly being asked by their patients to provide a report in support of an application for them to retire from work on the grounds of ill health. There is evidence that some applications may be motivated more by financial incentives than by ill health. Doctors should be wary of a conflict of interest, know the pension company's criteria for ill health retirement and provide objective medical evidence. The decision as to whether the patient fulfils the criteria is best left to another doctor who is acting as an advisor to the pension company.     

Four years of the Switched Multi-megabit Data Service

Over the last four years BT's Switched Multi-megabit Data Service has been a major success for the company. This has been due to a unique combination of features that make it genuinely easy for customers to dimension, manage and grow their wide area data networks cost effectively. This paper outlines how the underlying technology and service performance supports a set of features which translate into major business benefits and contribute to competitive advantage. The technology evolution path for SMDS in an ATM-based multi-service environment is described and service interworking scenarios discussed.     

Magnetic fields and childhood cancers

We present an examination of available dose-response data on EMF and childhood cancer in the epidemiologic literature. We conclude that evidence of dose-response exists for childhood leukemia and that causality remains a scientifically defensible explanation for the epidemiologic results produced thus far on this disease in relation to EMF exposure