A miniature microcontroller curve tracing circuit for space flight testing transistors

This paper describes a novel miniature microcontroller based curve tracing circuit, which was designed to monitor the environmental effects on Silicon Carbide Junction Field Effect Transistor (SiC JFET) device performance, while exposed to the low earth orbit environment onboard the International Space Station (ISS) as a resident experiment on the 7th Materials on the International Space Station Experiment (MISSE7). Specifically, the microcontroller circuit was designed to operate autonomously and was flown on the external structure of the ISS for over a year. This curve tracing circuit is capable of measuring current vs. voltage (I-V) characteristics of transistors and diodes. The circuit is current limited for low current devices and is specifically designed to test high temperature, high drain-to-source resistance SiC JFETs. The results of each I-V data set are transmitted serially to an external telemetered communication interface. This paper discusses the circuit architecture, its design, and presents example results.

Modern management of complex open abdominal wounds of war: a 5-year experience

BACKGROUND

Optimal management of the open abdomen remains controversial.

STUDY DESIGN

Retrospective review of patients injured during Operations Enduring Freedom and Iraqi Freedom returning to Walter Reed Army Medical Center (WRAMC) from January 2003 to October 2007 for treatment of open abdomen.

RESULTS

Three hundred fifty-four patients were evacuated to WRAMC after laparotomy, including 86 patients (24%) with open abdomen. Three transferred patients were excluded. Eighty-three patients, mean age 26 years (range 18 to 54 years), sustaining injury from secondary blast (n = 47), gunshot (n = 29), and blunt trauma (n = 7) were studied. Surgical management included early definitive abdominal closure (EDAC, n = 56; 67%), primary fascial closure (n = 15; 18%), planned ventral hernia (PVH, n = 9; 11%) and vacuum-assisted closure with AlloDerm (n = 3; 4%). EDAC closure involves serial closure with Gore-Tex Dualmesh and final closure supplemented with polypropylene mesh (62%) or AlloDerm (31%). There was no substantial difference in injury mechanism, age, length of evacuation to WRAMC, or Injury Severity Score (average 30) according to closure type. Complications included removal of infected prosthetic mesh in 4 EDAC closure patients (5%). Overall morbidity was lowest (60%) in primary repair patients (p = 0.01). Rates of deep venous thrombosis, pulmonary embolism, abdominal wall hematoma, and infection did not differ between groups. Fistula rate was increased with PVH (20%). Two patients with PVH died. PVH and EDAC mesh complications have been minimized in the last 2 years of the study.

CONCLUSIONS

Primary closure of fascia is ideal but not always possible. Early definitive closure has avoided PVH. Mesh-related complications have decreased with time.

Demographics, family histories, and psychological characteristics of prostate carcinoma screening participants

BACKGROUND

The goals of this study were to 1) understand the reasons that men seek prostate carcinoma screening, in light of the ongoing medical controversy surrounding screening; and 2) assess the level of psychological distress and perceived risk among men seeking screening, and whether or not these variables were dependent on a man's family history of prostate carcinoma.

METHODS

The subjects were 126 men (40% had a family history of prostate carcinoma) who participated in a free prostate carcinoma detection program. Questionnaires, which were completed prior to prostate carcinoma screening, included demographic and medical information, reasons for screening participation, general and cancer-related psychological distress, and perceived risk for prostate carcinoma.

RESULTS

Among both family history groups, self-referral was the most common reason for attending the screening, compared with receiving a recommendation from a health professional or from a friend or family member. Men with a positive family history were not more distressed than those without a family history; but as the authors predicted, men with a positive family history of prostate carcinoma did report higher levels of perceived risk relative to those without a family history. In addition, an interaction revealed that psychological distress was greater among men with a family history only among those who also reported elevated perceived risk.

CONCLUSIONS

Similar to other prostate carcinoma screening programs, men in the current sample largely elected to attend the screening on their own. Furthermore, although perceived risk was higher among men with a family history compared with those without a family history, psychological distress was greater among men with a family history only among those who also reported elevated perceived risk. Thus, among men with a family history of the disease, perceived risk may be a marker of elevated psychological distress. Screening programs should assess family history and perceived risk because of the potential psychological implications for screening participants.

Peer reviewed: when pollution prevention meets the bottom line

Cost savings are not always enough to convince industry to adopt prevention actions.

A body-system approach to infection control and discharge planning

Discharge planning is a complex process that must address all patient needs, including safety and infection control. A tremendous amount of collaboration and consideration of all factors that impact on utilization, quality assurance, and discharge planning are necessary from the infection control nurse and discharge planning nurse. The Joint Commission on Accreditation of Healthcare Organizations has adopted standards to address timely and smooth transitions of patients to appropriate posthospital care. Infection control policies must address these standards.

Infection control and discharge planning: cooperation essential to risk management

The infection control nurse must accept the importance of discharge planning and begin to consult with other health care professionals early in the process, thus ensuring the inclusion of infection control for continuity of care and patient safety for the transition from hospital to extended care facility.

Structural changes induced in glycogen phosphorylase b by the binding of glucose and caffeine

The allosteric inhibitors glucose and caffeine cause significant structural alterations in glycogen phosphorylase b (1,4-alpha-D-glucan:orthophosphate alpha-D-glucosyltransferase, EC 2.4.1.1). Both cause a masking of two sulfhydryl groups and a reduction of binding affinity for AMP. Caffeine produces an alteration in the microenvironment of the binding site for 1-anilin-naphthalene-8-sulfonate, resulting in a decrease of quantum yield of fluorescence and a change in spectral distribution. The binding of glucose is exothermic with an enthalpy of binding of -6.0 kcal/mol. Glucose causes a change in the molecular ellipticity in the pyridoxal-5'-phosphate region. The implications of these results are discussed.

Ligand binding and self-association of phosphorylase b

The mutual influence of ligand binding and self-association has been examined for phosphorylase b in the presence of a series of small ligands. The stepwise equilibrium constants describing the mutual dependence have been evaluated and discussed in terms of possible molecular mechanisms.

Structural changes accompanying the removal of pyridoxal 5'-phosphate from phosphorylase b

The changes in physical properties accompanying the removal of pyridoxal 5'-phosphate from glycogen phosphorylase b have been examined. The apoenzyme retains a high degree of structural rigidity, as determined from the time decay of anisotropy. The bulk of the secondary structure remains intact, although a significant change in circular dichroism indicates some degree of alteration. The mobility of a sulfhydryl-linked spin label increases. The restoration of pyridoxal 5'-phosphate reverses this effect, with indication of interaction between subunits. One or more new binding sites for 1-anilinonaphthalene-8-sulfonate appear for the apoenzyme. The kinetics of the recombination of pyridoxal 5'-phosphate with the apoenzyme, as monitored by difference spectra, indicate a high activation energy for the process. The apoenzyme is a reversibly associating system at 20-30 degrees C, pH 7.0.

The interactive binding of two ligands by an allosteric protein

The equilibrium constants describing the simultaneous binding of the ligands AMP and 1-anilinonapthalene-8-sulfonate (ansyl) by phosphorylase b have been evaluated. The binding of a single molecule of AMP per dimer unit causes only a moderate reduction in the binding constant for a single molecule of ansyl, but reduces that for a second molecule of ansyl by 10-fold. The binding of two molecules of AMP per dimer unit almost abolishes the binding of a single molecule of ansyl.