Accounting for uncertainty in control-relevant statistics

To make appropriate decisions based on common indices used in control, both the point estimates and their uncertainties must be known. Many control-relevant statistics, such as model predictions, gain margins and other frequency domain quantities, are functions of parameters of process models. Confidence regions for these quantities are most often calculated under the assumption that these quantities have an asymptotic limiting normal distribution. These confidence regions may be erroneous, and very misleading, as the asymptotic results ignore the influence of parameter nonlinearities. In addition, proximity of the model parameters to stability/invertibility boundaries also distorts the confidence regions from those predicted from asymptotic theory. Generalized profiling is a flexible numerical method for constructing confidence intervals and confidence regions for model parameters, and functions of model parameters. Applications in nonlinear regression [D. Bates, D. Watts, Nonlinear Regression Analysis and Its Applications, John Wiley & Sons, New York, 1988] indicate that it provides a much more accurate representation of uncertainty in those instances when the asymptotic uncertainty results are inaccurate or misleading. Generalized profiling is based on the likelihood approach to quantifying uncertainty. The numerical construction of these likelihood uncertainty regions requires solution to a series of constrained optimization problems. Computationally efficient diagnostic tests, motivated by profiling, are developed. These can be effectively employed as screening tools to indicate when the asymptotic results are most likely to be inadequate.     

When Grades Determine Self-Worth: Consequences of Contingent Self-Worth for Male and Female Engineering and Psychology Majors.

The impact of grades on daily self-esteem, affect, and identification with major was examined in a sample of 122 male and female students majoring in engineering and psychology. Self-esteem, affect, and identification with major increased on days students received good grades and decreased on days they received poor grades: basing self-esteem on academic competence moderated the effect of bad grades. Bad grades led to greater drops in self-esteem but not more disidentification with the major for women in engineering. Instability of self-esteem predicted increases in depressive symptoms for students initially more depressed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Nationwide survey of fluoroscopy: radiation dose and image quality

PURPOSE: To determine the average abdominal entrance air kerma, low-contrast sensitivity, and spatial resolution in upper gastrointestinal tract fluoroscopy in the United States. MATERIALS AND METHODS: A random sample of fluoroscopic facilities was selected to be surveyed for the Nationwide Evaluation of X-ray Trends program. Measurements were performed by using a newly developed fluoroscopic phantom. The surveys were conducted by state radiation control personnel. RESULTS: Average air kerma rates 1 cm above the tabletop, free in air, were 43 mGy/min (n = 340). The rate increased to 64 mGy/min when a 1.6-mm-thick copper filter, which simulated the use of barium contrast medium, was added to increase attenuation. The average entrance air kerma, free in air, for radiographs was 3.4 mGy, and an average of 12 radiographs were obtained per examination. Of 352 facilities surveyed, 306 (87%) were able to resolve wire mesh with 20 or more lines per inch. Of 339 facilities for which percentage contrast could be calculated, 192 (57%) had minimum percentage contrast values of 4% or more. CONCLUSION: Spatial resolution for fluoroscopy is adequate for most of the facilities surveyed, but a substantial proportion of facilities could not visualize low-contrast test objects, which strongly suggests image quality problems.     

The emerging professional adhocracy: A general framework of responsive organizing (a republication).

This reprinted article originally appeared in Consulting Psychology Journal: Practice and Research, 1997, Vol 49(1), 25-34. (The following abstract of the original article appeared in record 1997-30041-003.) Offers a framework of the characteristics of the responsive organization. A responsive organization is one in which structures and procedures enhance the organization's ability to take advantage of the changes in the environment. Responsiveness, in this case, is more than just being reactive; it means that an organization is able to anticipate change and maintain a proactive orientation to the external environment. Within the framework discussed, the authors also include some of the problems that might be expected in this new organizational form. It is suggested that these tools will allow for the systematic examination of organizational performance and assist change agents in facilitating efforts intended to result in more responsive organizing. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Risk factors and clinical presentation of acute primary HIV infection in India

CONTEXT: Most previous studies of clinical presentation and risk factors in early human immunodeficiency virus (HIV) infection have relied on retrospective analyses and referred seroconverters, and thus were subject to possible bias. OBJECTIVES: To apply a method based on measurement of prevalent HIV-1 p24 antigenemia for identification of risk factors for newly acquired HIV infection and to describe the signs and symptoms of acute HIV infection. DESIGN AND SETTING: Nested case-control study in Pune, India. PARTICIPANTS: HIV antibody-negative persons attending 2 sexually transmitted disease (STD) clinics between May 1993 and June 1996. OUTCOME MEASURES: Prevalent p24 antigenemia, risk factors for HIV infection, and clinical symptoms of acute primary HIV infection. RESULTS: Of 3874 HIV antibody-negative persons tested, 58 (1.5%) were p24 antigen positive at initial presentation to the clinics. Unprotected sexual contact with a commercial sex worker (CSW) was reported by 39 (77%) of the 51 p24 antigenemic men, compared with 131 (51 %) of 255 control men (adjusted odds ratio [AOR], 3.4; 95% confidence interval [CI], 1.2-9.6; P=.02). The presence of an active genital ulcer at the time of screening was found in 46 (79%) of the 58 p24 antigenemic men and women, compared with 137 (47%) of the 290 control subjects (AOR, 4.2; 95% CI, 2.0-9.0; P<.001). Signs and symptoms independently associated with p24 antigenemia in HIV antibody-seronegative persons included fever, which was reported by 28 (48%) of the 58 p24 antigenemic subjects, but only 52 (18%) of the 290 control subjects (AOR, 4.7; 95% CI, 2.4-9.0; P<.001). Joint pain was reported by 10% of subjects recently HIV infected, compared with 2% of the control subjects (AOR, 6.5; 95% CI, 1.7-24.8; P=.006). Night sweats were reported by 9% of the p24 antigenemic, but only 1% of the control subjects (AOR, 9.1; 95% CI, 1.7-47.6; P=.009). Overall, fever, joint pain, and/or night sweats were reported in 27 (47%) of the 58 subjects with recent HIV infection. CONCLUSIONS: This systematic case-control study of p24 antigen screening in HIV-seronegative patients attending STD clinics in India identified unprotected sex with a CSW and a genital ulcer as independent risk factors associated with newly acquired HIV infection. In addition, p24 antigen positivity identified recent fever, night sweats, and arthralgias as symptoms that may be predictive of recent HIV infection. In a study of patients attending STD clinics in India, screening for p24 antigen in HIV antibody-negative persons was found to be a reliable and effective research method for determining recent risk behavior and identifying clinical signs of acute primary HIV infection.     

Identification of a reservoir for HIV-1 in patients on highly active antiretroviral therapy

The hypothesis that quiescent CD4+ T lymphocytes carrying proviral DNA provide a reservoir for human immunodeficiency virus-type 1 (HIV-1) in patients on highly active antiretroviral therapy (HAART) was examined. In a study of 22 patients successfully treated with HAART for up to 30 months, replication-competent virus was routinely recovered from resting CD4+ T lymphocytes. The frequency of resting CD4+ T cells harboring latent HIV-1 was low, 0.2 to 16.4 per 10(6) cells, and, in cross-sectional analysis, did not decrease with increasing time on therapy. The recovered viruses generally did not show mutations associated with resistance to the relevant antiretroviral drugs. This reservoir of nonevolving latent virus in resting CD4+ T cells should be considered in deciding whether to terminate treatment in patients who respond to HAART.     

Smooth-muscle hamartoma of the tunica dartos of the scrotum: report of a case

Corticosteroids are effective in bringing about a clinical remission in patients with ulcerative colitis. However, in severely relapsed cases, corticosteroids are not always effective even when a high dosage is administered. In addition, the long-term use of corticosteroids often causes serious side effects. Therefore, an alternative treatment for active ulcerative colitis is necessary in order to avoid these clinical problems. In the present pilot study, the efficacy of leukocytapheresis using a centrifugal procedure was evaluated for corticosteroid-resistant, active ulcerative colitis. Fourteen patients with corticosteroid-resistant severely active ulcerative colitis were treated by leukocytapheresis. Thirteen patients (92.9%) achieved clinical remission within 4 weeks after the apheresis, and remained in remission for 8 months on average without any additional corticosteroid therapy. In the remaining patient, in whom remission was not induced, a total colectomy was performed immediately after the fourth course of leukocytapheresis. No significant side effects were noticed throughout the therapy. Both colonoscopic and histological examinations confirmed the beneficial effect of this procedure in terms of the reduction of severe inflammation of the affected colon. We found that the expression of two adhesion molecules, L-selectin and VLA4a, on the surface of peripheral leukocytes was decreased after this new therapy.     

A Critical Evaluation of Interlaboratory Data on Total,Elemental, and Isotopic Carbon in the Carbonaceous Particle Reference Material,NIST SRM 1649a

Because of increased interest in the marine and atmospheric sciences in elemental carbon (EC), or black carbon (BC) or soot carbon (SC), and because of the difficulties in analyzing or even defining this pervasive component of particulate carbon, it has become quite important to have appropriate reference materials for intercomparison and quality control. The NIST “urban dust” Standard Reference Material^® SRM 1649a is useful in this respect, in part because it comprises a considerable array of inorganic and organic species, and because it exhibits a large degree of (¹⁴C) isotopic heterogeneity, with biomass carbon source contributions ranging from about 2 % (essentially fossil aliphatic fraction) to about 32 % (polar fraction).A primary purpose of this report is to provide documentation for the new isotopic and chemical particulate carbon data for the most recent (31 Jan. 2001) SRM 1649a Certificate of Analysis. Supporting this is a critical review of underlying international intercomparison data and methodologies, provided by 18 teams of analytical experts from 11 institutions. Key results of the intercomparison are: (1) a new, Certified Value for total carbon (TC) in SRM 1649a; (2) ¹⁴C Reference Values for total carbon and a number of organic species, including for the first time 8 individual PAHs; and (3) elemental carbon (EC) Information Values derived from 13 analytical methods applied to this component. Results for elemental carbon, which comprised a special focus of the intercomparison, were quite diverse, reflecting the confounding of methodological-matrix artifacts, and methods that tended to probe more or less refractory regions of this universal, but ill-defined product of incomplete combustion. Availability of both chemical and ¹⁴C speciation data for SRM 1649a holds great promise for improved analytical insight through comparative analysis (e.g., fossil/biomass partition in EC compared to PAH), and through application of the principle of isotopic mass balance.