The role of microstructural evolution during spark plasma sintering on the soft magnetic and electronic properties of a CoFe–Al2O3 soft magnetic composite

Journal of Materials Science - For transformers and inductors to meet the world’s growing demand for electrical power, more efficient soft magnetic materials with high saturation magnetic...     

An Approximation to the Negative Moments of the Positive Binomial Useful in Life Testing

The purpose of this paper is to obtain the mean and variance of the maximum likelihood estimator of the scale parameter of a Weibull distribution where the sample is censored at a fixed time. It will be shown that these moments are functions of the negative moments of the positive binomial distribution. A simple approximation is obtained for the negative moments of the positive binomial, thus giving an approximate expression for the mean and variance of the estimator.     

Avalanches on a conical bead pile: scaling with tuning parameters

Uniform spherical beads were used to explore the scaling behavior of a granular system near its critical angle of repose on a conical 3D bead pile. We found two tuning parameters that could take the system to a critical point. The existence of those tuning parameters violates the fundamental assumption of self-organized criticality, which proposed that complex dynamical systems self-organize to a critical point without need for tuning. Our avalanche size distributions were well described by a simple power-law, as is characteristic of a critical point, with the power τ = 1.5 when dropping beads slowly onto the apex of a bead pile from a small height. However, we could also move the system from the critical point using either of two tuning parameters: the height from which the beads fell onto the top of the pile or the region over which the beads struck the pile. As the drop height increased, the system did not reach the critical point yet the resulting distributions were independent of the bead mass, coefficient of friction, or coefficient of restitution. All our apex-dropping distributions for any type of bead (glass, stainless steel, zirconium) showed universality by scaling onto a common curve with τ = 1.5 and σ =?1.0, where 1/σ is the power of the tuning parameter. From independent calculations using the moments of the distribution, we find values for τ = 1.6 ± 0.1 and σ =?0.91 ± 0.15. When beads were dropped across the surface of the pile instead of solely on the apex, then the system also moved from the critical point and again the avalanche size distributions fell on a common curve when scaled similarly using the same values of τ and σ. We also observed that an hcp structure on the base of the pile caused an emergent structure in the pile that had six faces with some fcc or hcp structure; this structure did not affect the distribution of avalanche sizes.     

Perceiving group members accurately, or why can't we all just agree: Comment on Sullivan and Reno (1999).

M. P. Sullivan and R. R. Reno (1999) (see record 1999-03790-003) provided evidence that group members can accurately assess the task-related performance of other group members, thus contributing to the small number of studies linking interpersonal perceptions to objective criteria. This evidence, along with Sullivan and Reno's finding that consensus does not exist for liking (i.e., liking is more a function of the relationship between target and perceiver rather than anything specific to either), may have important implications for theorists and clinicians alike. Unfortunately, Sullivan and Reno may have confounded the appropriate levels of analysis used to frame their questions and justify their conclusions. This comment explores the level-of-analysis issue and considers some group therapy implications of lack of consensus for likability. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Exposure to antibiotics induces expression of the Mycobacterium tuberculosis sigF gene: implications for chemotherapy against mycobacterial persistors

BACKGROUND: Although many studies have investigated macromolecular uptake in the stomach and small intestine, little is known about macromolecular uptake in the colon. AIMS: To investigate the mechanisms involved in the transport of large antigenically intact macromolecules across the proximal and distal colonic epithelium in the rabbit. METHODS: The mucosal to serosal movement of bovine serum albumin (BSA) was examined in modified Ussing chambers under short circuited conditions. The mucosal surface was exposed to varying concentrations of BSA, and after a 50 minute equilibration period, the mucosal to serosal flux of immunologically intact BSA was determined by ELISA. Total BSA flux was determined by the transport of radiolabelled 125I-BSA. RESULTS: Intact BSA transport in proximal and distal colonic tissue showed saturable kinetics. Intact BSA transport in the proximal and distal segment was 7% and 2% of the total 125I-BSA flux respectively. Immunologically intact BSA transport in the distal segment was significantly less than that in the proximal segment. Intact BSA transport in the proximal colon was significantly reduced following treatment with sodium fluoride, colchicine, and tetrodotoxin. Cholinergic blockade had no effect on the uptake of intact BSA. Conclusion: The findings indicate that the transport of intact macromolecules across the proximal and distal large intestine is a saturable process. Further, intact BSA transport in the proximal colon is an energy dependent process that utilises microtubules and is regulated by the enteric nervous system.     

Infertility update: use of assisted reproductive technology

OBJECTIVE: To describe assisted reproductive technology (ART) and use of medications during these procedures. DATA SOURCES: Recent clinical literature. STUDY SELECTION: Not applicable. DATA EXTRACTION: Not applicable. DATA SYNTHESIS: ARTs are procedures used in treatment of infertility that involve removal of oocytes and their manipulation outside the woman's uterus. The simplest form of ART, in vitro fertilization, involves aspirating eggs from the ovaries, fertilizing them outside the body, and transferring the embryos into the uterus at the four- to eight-cell stage. Experimental regimens for in vitro fertilization include use of various medications (gonadotropin-releasing hormone agonists, human menotropins, follicle-stimulating hormone, growth hormone) at varying points in the menstrual cycle and after introduction of the embryo into the uterus. Human chorionic gonadotropin has been used to increase implantation of embryos during the woman's luteal phase. Gamete intrafallopian transfer (GIFT) involves transfer of oocytes and sperm into the fallopian tubes, where fertilization takes place. This technique has the advantage of causing the zygote to enter the uterus at the time it would during natural conception. Zygote intrafallopian transfer is similar to GIFT, except that fertilization occurs in vitro, with embryos placed in the fallopian tubes at the two-cell stage. Various micromanipulation techniques and innovative sperm aspiration procedures are currently under development. CONCLUSION: Many advancements have been made in ART, and pharmacists who understand these procedures can serve patients by providing medication information in an empathetic and supportive manner.     

Glycosylation is essential for functional expression of a human brain ecto-apyrase

The importance of N-linked glycosylation for the function and oligomerization of an E-type ATPase was examined by using tunicamycin and peptide N-glycosidase F, two agents used to prevent and remove glycosylations, respectively. The cDNA encoding a human ecto-apyrase (HB6), predicted to have seven N-linked glycosylation sites, was transiently expressed in mammalian COS cells and the resulting membrane preparations were treated with peptide N-glycosidase F (PNGase-F). PNGase-F caused a decrease in the apparent molecular weight of the protein (consistent with glycan removal) and a decrease in enzymatic activity over time. The ecto-apyrase was also expressed in the presence of tunicamycin, which completely prevented N-linked glycosylation, resulting in a nonglycosylated core protein devoid of ATP and ADP hydrolyzing activity. However, control and tunicamycin-treated cells expressed the enzyme to similar levels and localization. Interestingly, the quaternary structure of this E-type ATPase appears to be dependent upon the presence of glycan chains. The glycosylated ecto-apyrase exists as a homodimer in situ as assessed by both size-exclusion chromatography of detergent-solubilized ecto-apyrase and cross-linking of membrane-bound ecto-apyrase, in contrast to the enzymatically deglycosylated ecto-apyrase and the tunicamycin-treated ecto-apyrase. These results suggest that glycosylation is necessary for homooligomerization and nucleotide hydrolyzing activity, but not for expression and plasma membrane localization of the E-type ATPase. Similar results were obtained with another human ecto-apyrase, CD39, suggesting that the importance of glycosylation may be generalized to all membrane-bound E-type ATPases.     

Measurement of distributions of small-scale energy depositions from low-linear energy transfer particles using the superheated drop detector

We have developed a new detection method for measuring distributions of energy depositions from particles characterized by low linear energy transfers (LETs). In particular, we have developed a detection system to measure energy depositions produced by electrons and photons on nanometer scales. The detector is based upon the operational principles of the superheated drop detector (SDD). SDDs consist of tiny droplets of superheated liquid suspended within a gel-like emulsion. The SDDs in this study are fabricated using Freon-115 and a glycerol-based gel as the superheated liquid and host medium. This SDD configuration is operated as a threshold temperature-dependent detector for measuring nanoscopic distributions of energy depositions from low-LET particles. Measured results are compared to the calculated distributions of energy depositions along an electron track. A new electron track code, ESLOW3.1, is used to perform the computational study. Measurements show good agreement with computational results in the energy deposition range of 40-200 eV.