Phase transformation in AFM silicon tips.

We confirmed the occurrence of phase transformations in an atomic force microscopy silicon tip during loading and unloading experiments performed on a polycrystalline Ti sample. The influence of the phase transformations on the effective mechanical and electrical properties of the tip was observed with the help of load-unload curves measured simultaneously for the tip-sample contact stiffness k * and the effective electrical resistance of the system R eff. We used the atomic force acoustic microscopy (AFAM) method to determine the values of k *. To measure the changes in R eff, we combined a high voltage source/measure unit with the existing AFAM system. The data obtained showed that the phase transformation from Si-I to Si-II is preceded by other structural changes such as formation of distorted diamond structures and formation of Si-III. This conclusion was reached after observing a small hysteretic behavior in the load-unload stiffness curve accompanied by only very small changes in the resistance of the tip-sample system occurring on the unloading. The coinciding of a sudden increase in the values of the contact stiffness with a decrease in the resistance of the system indicated that the formation of metallic Si-II occurred in the subsequent measurements. The interpretation of our results found confirmation in the results of molecular dynamics and atomistic simulations performed for silicon under nanoindentation experiments.

[The pelvic subcutaneous cross-over internal fixator]. / Der subkutane ventrale Fixateur interne (SVFI) am Becken.

The pelvic subcutaneous cross-over internal fixator is a minimally invasive technique for the fixation of instable anterior pelvic ring fractures. A USS-II-VAS screw is anchored bilaterally in the supra-acetabular region of the os ileum by a mini-incision approach. An angled fixation rod is inserted subcutaneously and after successful closed reduction attached to the screws forming a locking internal fixation. In a retrospective study of the clinical and radiological outcomes of 19 patients after an average follow-up of 2.54 years, results were excellent and good in 31.6%, moderate in 63.2% and poor in 5.3%. Complications were one wound infection, one loosening of the VAS screw and seven temporary lesions of the lateral femoral cutaneous nerve. The main benefits are a simple surgical technique preventing damage to soft tissue, a low risk of neurovascular lesions and the avoidance of pin infections. Moreover patients with multiple trauma profit from a shorter time of surgery and greater comfort allowing a prone position. The new procedure combines the advantages of internal osteosynthesis and a minimally invasive technique, providing early mobilization under full-weight bearing for instable pelvic fractures.

Learned helplessness in diabetic youths.

Determined the relationships among the learned helplessness attributional style, depression, regimen adherence, and metabolic control in a sample of diabetic youth. Fifty children (20 male and 30 female) between the ages of 10 and 16 completed the Children's Attributional Style Questionnaire and the Children's Depression Inventory. Regimen adherence was assessed with three 24-hr recall interviews conducted separately with patients and their mothers over a 1-week period. Metabolic control was measured by glycosylated hemoglobin A1 (HbA1). Learned helplessness was significantly associated with depression (p less than .001) and HbA1 (p less than .02), but was not associated with regimen adherence. Depression was unrelated to regimen adherence and metabolic control. The adherence measures together accounted for 24% of the variance of HbA1. Significant correlations were obtained between HbA1 and the exercise (p less than .05) and eating/testing frequency (p less than .05) adherence factors, indicating that lower levels of adherence were associated with worse metabolic control. Age, pubertal status, sex, disease duration, and SES were unrelated to regimen adherence and metabolic control. These results support the notion that the learned helplessness attributional style for negative events is related to both depression and long-term metabolic control problems in diabetic youths.

Psychological compensation in the individual with life-threatening illness: A study of adolescents with cystic fibrosis.

A sample of adolescents with cystic fibrosis was compared with a matched control group in a number of psychological dimensions. It was found that there were no significant differences between the groups in the aspects measured, and the reasons for this were explored.

Radioimmunoassay studies of intestinal calcium-binding protein in the pig. I. Identification of intestinal calcium-binding protein in blood and response to a low calcium diet.

We have developed a radioimmunoassay for porcine intestinal calcium-binding protein (CaBP) and have used it to detect CaBP in pig plasma. Plasma CaBP is identical to intestinal CaBP on the basis of immunological activity, molecular size, and molecular charge properties. The plasma CaBP concentration was greater in the portal blood than in mixed venous blood, suggesting that blood CaBP originates in the gut. Two of four 15-week-old littermate pigs were placed on a low calcium diet (0.15% calcium, 0.65% phosphorus) and two on a control diet (0.65% calcium, 0.65% phosphorus). After 2 weeks, the entire small intestine was removed and divided into nine 1.8-m segments. CaBP was assayed in both plasma and intestinal mucosa. When the two pigs on a low calcium diet were compared with two control pigs, there was a general increase in immunoreactive CaBP in both plasma and intestinal mucosa. However, there was no increment in immunoreactive CaBP in the first 1.8-m segment of small intestine. Seventy-one percent of the increment in CaBP occurred distal to the first two segments. The largest fractional low calcium diet effect occurred in the ileum. The mean CaBP concentration for the total small intestine increased by a factor of 1.9. The plasma CaBP concentration increased by a factor of 2.6. In these pigs, plasma CaBP was a more reliable indicator of change in CaBP status than was the measurement in the proximal gut segment which contained the duodenum. The assay of CaBP in blood is convenient and may obviate the sampling errors inherent in intestinal biopsy.

Radioimmunoassay studies of intestinal calcium-binding protein in the pig. II. The distribution of intestinal CaBP in pig tissues.

Using a specific radioimmunoassay for porcine intestinal calcium-binding protein (CaBP), we have measured the concentration of CaBP in the various tissues and organs of normal pigs. Intestinal CaBP was present in highest concentration in the upper small intestine, with lower concentrations in the distal small intestine. Intestinal CaBP was also found, in lower concentrations, in kidney, liver, thyroid, pancreas, and blood. In all other tissues, including parathyroid, bone, skeletal muscle, and brain, CaBP immunoreactivity was undetectable or less than in blood. The elution profile of calcium-binding activity and immunoreactivity from gel filtration analysis of kidney and parathyroid extracts suggest that the calcium-binding protein in the parathyroid gland, and the major calcium-binding protein(s) in the kidney, are chemically and immunochemically different from intestinal CaBP.