Power quality disturbance data compression using wavelet transformmethods

In this paper, the authors present a wavelet compression technique for power quality disturbance data. The compression technique is performed through signal decomposition, thresholding of wavelet transform coefficients and signal reconstruction. Threshold values are determined by weighting the absolute maximum value at each scale. Wavelet transform coefficients whose values are below the threshold are discarded, while those that are above the threshold are kept along with their temporal locations. The authors show the efficacy of the technique by compressing actual disturbance data. The file size of the compressed data is only one-sixth to one-third that of the original data. Therefore, the cost related to storing and transmitting the data is significantly reduced     

Batteries for low power electronics

Progress in battery technology is closely tied to that in electronics, however, it is slow in comparison. Growth in new systems once in production, is also slow, depending upon the development of new devices which need their performance characteristics. This has been true, in particular for lithium cells operating at 3 V. Older electrochemical systems such as C-Zn, alkaline, Zn-air, NiCd, and lead-acid continue to get better, and maintain the market for devices which can use them. Primary lithium batteries are growing in use as new devices are designed around their higher voltage and superior shelf life. The Li-MnO₂ system dominates the commercial marker. At least 16 manufacturers produce many sizes and configurations from high rate “D” cells to 50 mAh thin, flat cells. Two new secondary (rechargeable) systems, nickel-metal hydride and lithium ion, have recently been introduced They are growing at a rapid rate in response to environmental concerns and the need for higher energy density. Other secondary systems such as Zn-air and lithium-polymer electrolyte are nearing commercial production. Environmental regulations continue to impact battery use and disposal, leading to more interest in secondary systems which can be reused many times before disposal. Mercury has largely been banned from use in primary batteries, both as a corrosion inhibitor for zinc and as a cathode in the mercuric oxide cell. Existing and emerging battery systems are discussed in terms of energy content, shelf and cycle life and other characteristics     

Differential trends in law grades of minority and nonminority law students.

Studied 3-yr trends in the law averages awarded to nonminority students and to 2 principal minority groups—Black students and Chicano students—in 2 sets of law schools that enrolled more than 900 Black students and more than 300 Chicano students. In 18 of 21 law schools, Black students showed greater improvement than White students when 3rd-yr grades were compared with 1st-yr grades. In 10 of 21 schools the improvement of Black students was significantly greater, statistically, than that of White students. Chicano students, who generally showed less prior educational disadvantage than Black students, exhibited differential improvement in 6 of 9 schools, but a statistically significant improvement in only 1 school. Various reasons for the differential improvements in grades are considered, including statistical artifacts (ceiling and floor effects, changes in criterion reliability, and unequal units of measurement in the grading of minority and nonminority students) and substantive factors such as course selection patterns, differences in the academic demands of each law school year, and support systems available to disadvantaged students. The implications of the findings are discussed for counseling students, for academic dismissal and probation policies, and for the study of effective institutional support services. (28 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Properly oriented heparin-decasaccharide-induced dimers are the biologically active form of basic fibroblast growth factor

Interaction of basic fibroblast growth factor (FGF-2) with heparin or heparan sulfate proteoglycans (HSPGs) is required for receptor activation and initiation of biological responses. To gain insight into the mechanism of activation of the FGF receptor by FGF-2 and heparin, we have used NMR, dynamic light scattering, and HSPG-deficient cells and cell-free systems. The first 28 N-terminal residues in FGF-2 were found to be highly mobile and flexible, consistent with the disorder found in both the NMR and X-ray structures. The structure of an FGF-2-heparin-decasaccharide complex that binds to and activates the FGF receptor was compared to a heparin-tetrasaccharide-induced complex that does not promote an interaction with the receptor. The major change observed upon the addition of the tetrasaccharide to FGF-2 was an increase in the correlation time consistent with the formation of an FGF-2 dimer. The NMR line widths of FGF-2 in the presence of the decasaccharide are severely broadened relative to the tetrasaccharide, consistent with dynamic light scattering results which indicate FGF-2 is a tetramer. The interaction of these heparin species with FGF-2 does not induce a significant conformational change in the overall structure of FGF-2, but small chemical shift changes are observed in both heparin and receptor binding sites. A trans-oriented symmetric dimer of FGF-2 is formed in the presence of the tetrasaccharide whereas two cis-oriented dimers in a symmetric tetramer are formed in the presence of the decasaccharide. This suggests that the cis-oriented FGF-2 dimer is the minimal biologically active structural unit of FGF-2. These data allow us to propose a novel mechanism to explain the functional interaction of FGF-2 with heparin and its transmembrane receptor.     

Diagnosis of infectious diseases: a cytopathologist's perspective

This review explores the role of the cytopathology laboratory in the detection and presumptive identification of microorganisms. Sample procurement by exfoliation, abrasion, and aspiration techniques, as well as a variety of cytopreparatory and staining methods, is reviewed. Emphasis is placed on the utility of fine-needle aspiration as a rapid, safe, and cost-effective diagnositic procedure. The role of rapid interpretation and specimen triage is also discussed. Cytomorphologic features and staining characteristics are presented for a spectrum of microorganisms potentially encountered in the cytopathology laboratory. Pitfalls in diagnosis and the usefulness of special stains and ancillary techniques are also evaluated. The importance of communication, collaboration, and clinical correlation is stressed.     

Comparison of tamoxifen effects on the actions of triiodothyronine or growth hormone in the ovariectomized-hypothyroid rat

Recent studies have suggested that a subset of estrogen responses arise via modulation of triiodothyronine (T3) actions, and depend on T3 for expression: other estrogen responses are not T3-dependent. Moreover, tamoxifen acts as a full estrogen agonist in T3-dependent responses but behaves as an antiestrogen in T3-independent responses. T3 directly induces a variety of metabolic enzymes and proteins, and also induces rat growth hormone (GH). Thus, some T3-dependent tamoxifen effects might reflect modulation of GH rather than T3 actions. To address this issue, tamoxifen effects on somatotropic and metabolic actions of T3 and GH were compared in ovariectomized rats with methimazole-induced hypothyroidism. Rats were given T3 (10 micrograms/kg/day) or ovine GH (2 mg/kg/day) with or without tamoxifen (0.5 mg/kg/day) for 30 days. GH was poorly effective in producing a sustained increase in somatic growth in hypothyroid rats compared to T3; nonetheless, GH effects to increase body weight, tibia length and serum insulin-like growth factor I while decreasing fat mass and evoking small increases in body temperature were not inhibited by tamoxifen. Tamoxifen also did not inhibit GH trends to increase tibia bone mineral density. T3 increased body temperature, insulin-like growth factor I levels and all measures of somatic growth and, unlike GH, increased food intake and tended to decrease tibia bone mineral density. Tamoxifen inhibited the somatotropic actions of T3 (including increases in insulin-like growth factor I levels), and produced significant increases in tibia bone mineral density only in T3-treated rats. Tamoxifen had no effect on T3 actions to increase food intake or body temperature. T3 alone increased fat mass and exhibited a tendency to decrease serum triglycerides: tamoxifen had no effect on these parameters in the absence of T3. However, coadministration of tamoxifen with T3 produced a marked decrease in fat mass and increased serum triglycerides. GH had no effect on serum triglycerides in either the presence or absence of tamoxifen. Serum glucose levels appeared normal in all groups. The data indicate that multiple tamoxifen effects on growth and metabolism may reflect modulation of T3 rather than GH actions.