Radar response to vegetation II: 8-18 GHz band

The results of experimental studies on the backscattering properties of corn, milo, soybeans, and alfalfa are presented. The measurements were made during the summer of 1973 over the 8-18 GHz frequency band. The data indicate that soil moisture estimation is best accomplished at incidence angles near nadir with lower frequencies while crop discrimination is best accomplished using two frequencies at incidence angles ranging from30degto65deg. It is also shown that temporal plant morphology variations can cause extreme variations in the values of the scattering coefficients. These morphological changes can be caused by growth, heavy rain, and in the case of alfalfa, harvesting.     

Structural damage to lactate dehydrogenase during copper iminodiacetic acid metal affinity chromatography

The stability of the enzyme lactate dehydrogenase (LDH) was evaluated by measuring structural damage and activity loss after exposure to copper-iminodiacetic acid (IDA) immobilized metal affinity chromatography (IMAC) under oxidizing conditions at pH 7.0. Oxidizing conditions were produced by adding reductants commonly employed in bioprocessing and biomedical applications (glutathione, beta-mercaptoethanol, dithiothreitol, cysteine, or ascorbate) and/or hydrogen peroxide to the mobile phase. Most of these additives have been shown recently to give rise to metal-catalyzed oxidation (MCO) reactions on copper-iminodicaetic acid IMAC columns. Structural damage in the form of increased susceptibility to proteolytic degradation, fragmentation, and cross-linking were measured. Increased sensitivity to proteolysis was significant in virtually all cases tested, even when activity remained high (>95% specific activity recovered). In contrast fragmentation and cross-linking were minimal in all cases, even when activity was low (<50%). As the damage was believed to have been caused primarily by MCO reactions, preventative measures consistent with this reaction pathway were tested. The most successful measure for all of the conditions studied was addition of the Cu+ chelating agent bicinchoninic acid (BCA) to the mobile phase. Decreased contact time with the column decreased damage in the case where glutathione was added. Removal of dissolved oxygen by nitrogen sparging and use of Tris-acetate buffer in place of phosphate had no measurable effect. The success of BCA addition in reducing structural damage and activity loss strengthens the conclusion that MCO reactions can occur on copper-iminodiacetic acid IMAC columns. However, the addition of BCA and the other protective measures described were not successful in eliminating the increased proteolytic susceptibility observed when LDH in buffer was exposed to the copper-charged column with no oxidizing additives. This suggests that at least one other pathway for damage exists. This damage is difficult to detect as it did not cause statistically significant losses in enzymatic activity, fragmentation, or cross-linking.     

Human immunodeficiency virus type 1 protease inhibitors: evaluation of resistance engendered by amino acid substitutions in the enzyme's substrate binding site

The human immunodeficiency virus type 1 (HIV-1) protease is a homodimeric aspartyl endopeptidase that is required for virus replication. A number of specific, active-site inhibitors for this enzyme have been described. Many of the inhibitors exhibit significant differences in activity against the HIV-1 and HIV type 2 (HIV-2) enzymes. An initial study was conducted to ascertain the HIV-1 protease's potential to lose sensitivity to several test inhibitors while retaining full enzymatic activity. The substrate binding sites of the HIV-1 and HIV-2 enzymes are almost fully conserved, except for four amino acid residues at positions 32, 47, 76, and 82. Accordingly, recombinant mutant type 1 proteases were constructed that contained the cognate type 2 residue at each of these four positions. The substitution at position 32 resulted in a significant adverse effect on inhibitor potency. However, this substitution also mediated a noted increase in the Km of the substrate. Individual substitutions at the remaining three positions, as well as a combination of all four substitutions, had very little effect on enzyme activity or inhibitor susceptibility. Hence, the four studied active site residues are insufficient to be responsible for differences in inhibitor sensitivity between the HIV-1 and HIV-2 proteases and are unlikely to contribute to the generation of inhibitor-resistant mutant HIV-1 protease.     

Hormonal responses to consecutive days of heavy-resistance exercise with or without nutritional supplementation

Nine resistance-trained men consumed either a protein-carbohydrate supplement or placebo for 1 wk in a crossover design separated by 7 days. The last 3 days of each treatment, subjects performed resistance exercise. The supplement was consumed 2 h before and immediately after the workout, and blood was obtained before and after exercise (0, 15, 30, 45, and 60 min postexercise). Lactate, growth hormone, and testosterone were significantly (P 相似文献   

Does stent placement improve the results of ineffective or complicated iliac artery angioplasty?

OBJECTIVE: This study was undertaken to determine the results and complications of stents placed for initially unsuccessful or complicated iliac percutaneous transluminal angioplasty (PTA), the effect of location (external iliac or common iliac) on outcome, and the influence of superficial femoral artery patency on benefit. DESIGN: From 1992 through 1997, 350 patients underwent iliac artery PTA at the authors' institutions. Of this group, 88 patients (88 arteries) had one or more stents placed after PTA (140 stents in total) for residual stenosis or pressure gradient (63 patients), iliac dissection (12 patients), long-segment occlusion (10 patients), or recurrent stenosis (3 patients). Thirty patients required the placement of more than one stent. The indications for PTA in these 88 patients were claudication (48 patients) and limb-threatening ischemia (40 patients). Forty-seven patients had stents placed in the common iliac, 29 patients had stents placed in the external iliac, and 12 patients had stents placed in both. Seventy-one arteries (81%) were stenotic, and 17 (19%) were occluded before PTA. Sixty-six arteries were treated by interventional radiologists, 15 by a vascular surgeon, and 7 jointly. MAIN OUTCOME MEASURE: Criteria for success included (1) increase of at least one clinical category of chronic limb ischemia from baseline or satisfactory wound healing, (2) maintenance of an ankle/brachial index increase of more than 0.10 above the preprocedure index, and (3) residual angiographic stenosis less than 25% and, for patients with pressure gradient measurements, a residual gradient less than 10 mm Hg. RESULTS: Stent placement was accomplished in all 88 patients with 16 (18%) major complications. Mean follow-up was 17 months (range, 3 to 48 months). By life-table analysis, success was 75% at 1 year, 62% at 2 years, and 57% at 3 years. No cardiovascular risk factor or independent variable was statistically significant in predicting success. There was no difference in success rates for common iliac or external iliac lesions. Superficial femoral artery patency did not correlate with outcome. CONCLUSIONS: Although stents can eliminate residual lesions and arterial dissection, these patients are likely to require adjuvant or subsequent procedures to attain clinical success. By controlling the PTA complication and treating the emergent problem, stents may allow for subsequent elective intervention.     

Socioeconomic status and health in women with systemic lupus erythematosus

OBJECTIVE: Health outcomes of patients with chronic illnesses are commonly worse in people of lower socioeconomic status (SES). We investigated psychosocial factors that may mediate the relationship between SES and measures of morbidity in women with systemic lupus erythematosus (SLE). METHODS: We collected information on SES, psychosocial factors, and health status in a cross sectional survey of 100 women with SLE. SES was rated using the Hollingshead Two-Factor Index, a weighted average of years of formal education and occupational prestige (higher Hollingshead Index=lower SES). Health status measures included the Health Assessment Questionnaire Disability Index (HAQ), the Systemic Lupus International Collaborating Clinics/American College of Rheumatology Damage Index (SLICC/ACR), the Systemic Lupus Activity Measure (SLAM), and the SLE Disease Activity Index (SLEDAI). Potential mediators consisted of 18 environmental, medical care, social, psychological, and behavioral factors. RESULTS: Patients with higher Hollingshead Indexes (lower SES) had more functional disability as measured by the HAQ (r=0.22: p=0.03) and more cumulative organ damage as measured by the SLICC/ACR Damage Index (r = 0.19; p=0.06). SES was not related to either the SLAM or SLEDAI. Significant univariate associations were present between the Hollingshead Index and 10 potential mediating variables: household crowding, insurance status, organizational barriers to medical care, depression, health locus of control by powerful others, SLE knowledge, social support, marital status, body mass index, and regular alcohol use. However, in multiple linear regression analyses, only 3 of these variables modified the relationship between Hollingshead Index and the HAQ: more severe depression scores, higher body mass index, and more restricted access to medical care. More severe depression and greater locus of control by powerful others tended to mediate the relationship between low SES and greater organ damage. CONCLUSION: SES is related to morbidity in women with SLE. There are identifiable and potentially modifiable mediators of this relationship.     

A special purpose digital system for musical instruction,composition, and performance

Language Resources and Evaluation -     

Reconstructions of family relationships: Parent–child alliances, personal distress, and self-esteem.

The aim of this study was to operationalize the structure of family relationships and examine how women's reconstructions of various family patterns during childhood and adulthood relate to their levels of depression, anxiety, and self-esteem. Using a sample of 93 women, ages 19 to 22, two family patterns emerged: (a) father-daughter alliance (FDA), whereby fathers seek intimacy and affection from their daughters instead of their wives and have emotionally distant marriages; and (b) mother-daughter triangulation (MDT), characterized by conflicted marriages whereby daughters are caught between their battling parents and mothers seek intimacy from their daughters instead of their husbands. Regression estimates suggest that childhood FDA significantly contributes to depression, anxiety, and low self-esteem even after controlling for the effects of childhood physical abuse and current FDA. Current MDT contributes to anxiety. (PsycINFO Database Record (c) 2010 APA, all rights reserved)