Numerical method and results for inviscid supersonic flow over a compressive ramp

An algorithm is presented for the steady, two-dimensional, inviscid, supersonic flow near a wall with a compressive turn. The wall is contoured to provide a centered, Prandtl-Meyer compression. The focal point of the compression is the origin of an oblique shock wave, a slipstream and a secondary disturbance. This disturbance is an expansion, a weak solution oblique shock, or a strong solution oblique shock. Although algebraic equations govern the flow in the vicinity of the focal point, a sophisticated algorithm is required for the solution, which does not always exist and is not always unique. For a range of incident Mach numbers ranging from 1.2 to 16, the near-field solution is compared with its well-known asymptotic far-field counterpart.     

Effects of threat in a performance appraisal interview.

Real-life appraisal interviews conducted by 92 manager-subordinate pairs were studied intensively. Reactions of subordinates were systematically obtained before and after their appraisal interviews and the proceedings in the actual interviews were carefully documented by trained Os. Measures of subsequent performance improvement realized as a result of the appraisal interviews were taken 12 wk. later. The results indicated that a manager's attempts to assist a subordinate by pointing up improvement needs were likely to be perceived by the subordinate as threatening to his self-esteem and to result in defensive behavior. The greater the threat, the less favorable the attitude toward the appraisal system and the less the subsequent constructive improvement in job performance realized. These reactions were strong to the extent that the subordinate had relatively low occupational self-esteem. Some practical implications for appraisal practices are cited. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Programmed Cell Death in the Small Intestine: Implications for the Pathogenesis of Celiac Disease

The small intestine has a high rate of cell turnover under homeostatic conditions, and this increases further in response to infection or damage. Epithelial cells mostly die by apoptosis, but recent studies indicate that this may also involve pro-inflammatory pathways of programmed cell death, such as pyroptosis and necroptosis. Celiac disease (CD), the most prevalent immune-based enteropathy, is caused by loss of oral tolerance to peptides derived from wheat, rye, and barley in genetically predisposed individuals. Although cytotoxic cells and gluten-specific CD4⁺ Th1 cells are the central players in the pathology, inflammatory pathways induced by cell death may participate in driving and sustaining the disease through the release of alarmins. In this review, we summarize the recent literature addressing the role of programmed cell death pathways in the small intestine, describing how these mechanisms may contribute to CD and discussing their potential implications.     

Effect of Ca and B incorporation into silicon oxycarbide on its microstructure and phase composition

Ca- and/or B-modified silicon oxycarbides were synthesized via pyrolysis of suitable polysilsesquioxane-based single-source precursors. Their polymer-to-ceramic transformation was investigated with thermogravimetric analysis, coupled with in situ evolved gas analysis. The prepared silicon oxycarbides were investigated with respect to their crystallization behavior, network architecture, and chemical compositions. The network connectivity in silicon oxycarbides can be affected/tuned upon using two different “tools”: (a) first, the use of network modifiers, such as Ca in our study, leads to a slight depolymerization of the network via generation of a small amount of Q³ sites; (b) second, the modification of silicon oxycarbide with B/Ca leads to a decrease of the carbon content in the network and thus to a significant decrease of its connectivity. Using these two different effects, the network connectivity in silicon oxycarbides can be finely tuned.     

Effect of Erythropoietin on the Expression of Murine Transferrin Receptor 2

Erythropoietin (EPO) downregulates hepcidin expression to increase the availability of iron; the downregulation of hepcidin is mediated by erythroferrone (ERFE) secreted by erythroblasts. Erythroblasts also express transferrin receptor 2 (TFR2); however, the possible role of TFR2 in hepcidin downregulation is unclear. The purpose of the study was to correlate liver expression of hepcidin with the expression of ERFE and TFR2 in murine bone marrow and spleen at 4, 16, 24, 48, 72 and 96 h following administration of a single dose of EPO. Splenic Fam132b expression increased 4 h after EPO injection; liver hepcidin mRNA was decreased at 16 h. In the spleen, expression of TFR2 and transferrin receptor (TFR1) proteins increased by an order of magnitude at 48 and 72 h after EPO treatment. The EPO-induced increase in splenic TFR2 and TFR1 was associated with an increase in the number of Tfr2- and Tfr1-expressing erythroblasts. Plasma exosomes prepared from EPO-treated mice displayed increased amount of TFR1 protein; however, no exosomal TFR2 was detected. Overall, the results confirm the importance of ERFE in stress erythropoiesis, support the role of TFR2 in erythroid cell development, and highlight possible differences in the removal of TFR2 and TFR1 from erythroid cell membranes.     

Examining how country-level science policy shapes publication patterns: the case of Poland

Scientometrics - This country case study describes how science policy instruments are designed to shape publication patterns and identifies the changes in researchers’ productivity that can...     

Assessment of the austemperability of high-silicon cast steels through Jominy hardenability tests

The austemperability of seven high silicon cast steels with different alloy contents was characteri sed. The maximum round bar diameter that can be fully austempered changed from about 10?mm for an unalloyed steel to more than 70?mm for a low-alloy steel. The austemperability was calculated by applying a procedure based on a standard Jominy test and the characterisation of the microstructure along the Jominy sample. The method, which was validated experimentally, creates a relatively simple procedure to measure austemperability. Processing factors such as the ability of the salt bath to extract heat and the austempering temperature are accounted for the method. The metallographic study revealed the influence of microsegregation on hardenability, which is particularly important for cast steels.     

Structure,nonlinearity, and system theory

The suggestion of writing, for some problems, nonlinear state equations not as dx/dt = F(x,u,t), but as dx/dt = [A(t,x)]x + [B(t,x)]u(t), which is more ‘constructive’ as re system perception and possible structural generalizations, is considered, supported by arguments related to the classification of switched circuits as linear and nonlinear. The point of the distinction is mainly that when solving dx/dt = F(x,u,t), one immediately dwells into the analytical problems related to pure mathematics, whereas for dx/dt = [A(t,x)]x + [B(t,x)]u(t), considering first a constant matrix [A], one introduces the system's physical structure and considering then [A(x)] sees the nonlinearity of the system as a dependence of the structure on the processes in it or on system's input. (This might be named structural response). The thinking in terms of structure better observes the engineering and physical degrees of freedom, which are relevant regarding applications. Some electronic systems and physical systems (e.g., hydrodynamic) are considered in these terms. The logical side is always the focus, and the pedagogical (even philosophical) side is not ignored. Copyright © 2013 John Wiley & Sons, Ltd.     

Magnetic field enhancement of electrochemical hydrogen evolution reaction probed by magneto-optics

External magnetic fields affect various electrochemical processes and can be used to enhance the efficiency of the electrochemical water splitting reaction. However, the driving forces behind this effect are poorly understood due to the analytical challenges of the available interface-sensitive techniques. Here, we present a set-up based on magneto- and electro-optical probing, which allows to juxtapose the magnetic properties of the electrode with the electrochemical current densities in situ at various applied potentials and magnetic fields. On the example of an archetypal hydrogen evolution catalyst, Pt (in a form of Co/Pt superlattice), we provide evidence that a magnetic field acts on the electrochemical double layer affecting the local concentration gradient of hydroxide ions, which simultaneously affects the magneto-optical and magnetocurrent response.     

A thin PANI and carrageenan–gold nanoparticle film on a flexible gold electrode as a conductive and low-cost platform for sensing in a physiological environment

In this work, we report the production of a layer-by-layer (LbL) film of gold nanoparticles stabilized with carrageenan (carr-AuNPs) interspersed with a conductive polyaniline (PANI) layer. Conventionally, PANI has poor electroactivity in physiological buffers, limiting its using in electrochemical biosensors. The films were prepared on low cost and easy to manufacture flexible gold electrodes (FEAu). Two adsorption sequences were tested for production of the films—PANI/carr-AuNP and carr-AuNP/PANI. The gold nanoparticle size and colloidal stability were characterized. The films were characterized by cyclic voltammetry, UV–visible spectroscopy and atomic force microscopy. The results showed the synergistic effects of the carr-AuNPs (120 nm) and PANI, which improved both the electrochemical response and the stability of the conductive polymer in physiological medium by three times. The presence of the carr-AuNPs in the film caused a significant increase in roughness of the FEAu-modified electrode compared to that of an unmodified electrode, resulting in an increased active electrode area. Studies of film growth by UV–Vis spectroscopy indicated that the deposition mechanisms of both films involved an auto-regulating adsorption process, with the same amount of material adsorbed in each coating step. The PANI/carr-AUNP film showed considerable improvement in stability and conductivity compared to PANI-only films in the physiological environment, which confers advantages for use as a biosensor.