Development and evaluation of the Air Travel Stress Scale.

Despite anecdotal evidence suggesting that air travel is personally demanding, little research has examined air travel stress. To address these issues, the author developed and evaluated the 1st known measure of air travel stress--the Air Travel Stress Scale--in 3 studies. Exploratory and confirmatory factor analysis indicated 3 components: (a) anxious reactions to adverse air travel events, (b) angry reactions to other passengers as well as an antecedent of air travel stress, and (c) the lack of trust that the airlines/airports will ensure one's comfort and safety. Each component had good internal reliability and test-retest reliability over a 6- to 7-week interval. Each component showed evidence for discriminant and convergent validity. Implications for research into understanding and intervening on air travel stress are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Performance of the Adaptive A/D Converter in Combined CW and Gaussian Interference

Previous analyses are extended to give the performance of the adaptive 2 bit A/D converter in combined CW and Gaussian interference. The converter is seen to give substantial conversion gain even when the direct sequence pseudonoise (DSPN) spread signal is much weaker than the Gaussian component of interference. The upper bound on conversion gain depends primarily on the relative strengths of the Gaussian and CW components of interference. The relevant relationships are given in graphical form.     

Increasing the up-link CW interference immunity of non-coherent direct sequence pseudonoise (DSPN) reception with on-board processing

The adaptive threshold A/D converter is by now a familiar technique for increasing the CW interference immunity of coherently detected direct sequence pseudonoise (DSPN) spread-spectrum signals, especially where the frequency of the CW interferer may be changing so rapidly and over such a large portion of the signalling bandwidth that well known spectrum excision techniques prove ineffective. The present paper extends the theory to the case of non-coherent reception of direct sequence pseudonoise (DSPN) signals. The A/D converter is found to perform well in both CW and Gaussian interference. Conversion gain is seen to persist even if the interference is intentionally pulsed at an optimally reduced duty factor (from the interferer's point of view) in the attempt to confuse the adaptive threshold. The specific case of 32-chip data symbols is treated, wherein the adaptation is applied strictly to individual symbols. In some cases these restrictions will actually improve performance.     

New formulation and plots for error probability in the pulse position modulation (PPM) photon counting satellite-to-earth channel

In digital satellite-to-earth transmission the entry of substantial undesired solar radiation into the receiver antenna is sometimes unavoidable. When the signal transmission takes the form of incoherent optical pulse position modulation (PPM) the parameters of signal and consequent intense noise can fall outside the range of routinely available classical numerical results on symbol error probability. This paper presents an alternative system for parametrization of signal and noise in the classical PPM channel, i.e. that characterized by Poisson photon arrival statistics for signal itself, the noise itself, and the signal plus noise. The resulting formulation for error probability, the scheme for probability calculation, and the simple, compact plots of error probability versus newly conceived parameters cover the entire range of signal and noise intensities, from weakest to strongest. Of course, when properly interpreted the new results agree entirely with classically available numerical results within the parametric range of the former.     

Cuticular hydrocarbons ofAedes hendersoni cockerell andA. triseriatus (SAY)

Field-caught adult male and femaleAedes hendersoni are difficult to distinguish from the sibling speciesA. triseriatus. We found that mosquitoes from the same sex of the sibling species can not be readily separated either by unique cuticular hydrocarbon components or by differences in percent composition of those components. Multivariate analysis of the cuticular hydrocarbon data does not provide good separation. Cuticular hydrocarbons were identified using gas chromatography electron-impact mass spectrometry and gas chromatography chemical-ionization mass spectrometry. Flame-ionization capillary gas chromatography was used for quantitative analysis of individual mosquitoes. Sixty-four hydrocarbons with chain lengths from C₁₆ to greater than C₄₆ were common to both species. Identified hydrocarbon components weren-alkanes, monomethylalkanes, dimethylalkanes, trimethylalkanes, and alkenes.Diptera: Culicidae.     

Prechlorination treatment of water to reduce chloroform levels

Drinking water that originates from surface water and is subsequently chlorinated at a water treatment plant probably contains trace amounts of chlroform and other trihalomethanes. In order to minimize these contaminants in drinking water in a simple and economical way, raw water is treated with hydrogen peroxide prior to the chlorination step. This procedure has been shown to be effective on Kansas River water and on synthetic water samples that contain humic acid.     

ANALYSIS OF A MARKOV CHAIN MODEL OF A MULTISTAGE MANUFACTURING SYSTEM WITH INSPECTION, REJECTION, AND REWORK

The authors present an informative application of Markov Chain Analysis to a multistage manufacturing problem. They also point out an error in the literature which has remained undetected for many years.

Edward A. Silver, Department Editor

Absorption analysis is applied to a Markov chain model of a multistage manufacturing process with inspection and reworking.     

Distribution and Abundance of Zooplankton in the U.S. Waters of Lake St. Clair, 1973

Zooplankton were obtained in the U.S. waters of Lake St. Clair at 28 stations sampled monthly from July through September 1973. Distribution and abundance of zooplankton were compared with physicochemical data collected concurrently and with previous studies on Lake St. Clair zooplankton.Sixty five species of Rotifera were recorded. Brachionus angularis, Conochilus unicornis and Synchaeta stylata were the three most abundant species. Total rotifers, averaging 47.1 individuals per liter over the study period, were about 30 times more abundant than the micro-crustaceans. The Cladocera were represented by 28 species, while five species of cyclopoids, seven calanoids and four harpacticoids were recorded from the Copepoda. Bosmina longirostris was the predominant micro-crustacean.Spatial distribution of zooplankton was hypothesized to be primarily dependent on current patterns generated by prevailing winds. The Canadian portion of the lake has a persistent eddy structure which apparently allows build-up of nutrient levels encouraging high zooplankton biomass. The U.S. side, however, experiences more rapid flow-through of St. Clair River water which accounts for lower zooplankton abundance. Despite the fast flushing rate on the U.S. side, a localized patch of high zooplankton density and a community structure indicative of eutrophic situations was consistently observed off the Clinton River Cutoff Canal. This is presumably due to nutrient loading from the Clinton River watershed.     

Acceptance and commitment therapy for smoking cessation: A preliminary study of its effectiveness in comparison with cognitive behavioral therapy.

This controlled preliminary trial determined the feasibility and initial effectiveness of a promising behavioral intervention for smoking: Acceptance and Commitment Therapy (ACT). In a quasi-experimental design, the ACT intervention condition used metaphors and experiential exercises focused on personal values to motivate quitting smoking and enhancing the willingness to experience internal cues to smoke (e.g., urges) and abstinence-related internal distress. The comparison condition was cognitive behavioral therapy (CBT)—the current standard in behavioral intervention for smoking cessation. Each treatment was delivered in seven weekly 90-min sessions in a group format to 81 (43 in ACT; 38 in CBT) adult smokers. Results show that the ACT treatment was as feasible as the CBT treatment. They also demonstrate promising evidence of ACT’s effectiveness: 30.2% intent-to-treat biochemically-supported 30-day point prevalence at twelve month follow-up, compared with 13.2% in the CBT condition (odds ratio = 5.13; p = .02). Replication in a well-powered, randomized, controlled trial is now needed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Postpericardiotomy syndrome in pediatric heart transplant recipients. Immunologic characteristics

Clinical features of postpericardiotomy syndrome (PPS) occur in pediatric heart transplant recipients despite immunosuppression, which raises questions about the mechanism of PPS. We studied the clinical and immunologic characteristics of 15 pediatric heart transplant patients, ages 1.1 to 17.8 years (mean, 7.5 years); 7 had clinical evidence of PPS (PPS+), and 8 were without clinical features of PPS (PPS-). Indicators of PPS included fever, irritability, pericardial friction rub, leukocytosis without other cause, and pericardial effusion. The onset of PPS was from 9 to 26 postoperative days (mean, 16 days). Immunosuppressive regimens were comparable up to the day of PPS diagnosis in PPS+ patients, and up to day 16 in PPS- patients (average onset of PPS in PPS+ patients). No differences were found between groups with respect to weight-adjusted dosages of cyclosporin A, azathioprine, or corticosteroids. Mean cyclosporin A levels in PPS+ and PPS- patients were 142 +/- 88 ng/mL (mean +/- standard deviation) and 265 +/- 122 ng/mL (p = 0.045), respectively. Echocardiographic data on 3 PPS+ patients within 1 day of PPS diagnosis revealed pericardial effusions ranging from 5 to 24 mm. No data were available on the remaining 4 PPS+ patients. Minimal pericardial effusions (< 10 mm) were seen in 4 PPS- patients during a comparable time period. One PPS- patient required pericardiocentesis. Endomyocardial biopsy rejection grade did not differ between groups. Means pretransplant soluble interleukin-2 receptor levels did not differ between PPS+ and PPS- patients (758 +/- 410 vs 653 +/- 270 IU/mL); nor did the PPS+ pretransplant levels differ from levels obtained 1 or 2 months postoperatively (700 +/- 437 and 751 +/- 367 IU/mL, respectively). Although pretransplant percentages of the standard T-cell (CD2, CD3, CD4, CD8) and B-cell (DR and CD19) markers differed from post-transplant values, the changes could be explained by the immunosuppressive regimen and did not differ between PPS+ and PPS- patients. In the PPS+ patients, however, there were significant increases in the proportion of activated helper T cells (CD4+/25+) and cytotoxic T cells (Leu-7+/CD8+) following heart transplantation in comparison with pretransplant levels. We speculate that these changes in activation marker in PPS+ patients suggest a possible role for cell-mediated immunity in the pathogenesis of PPS in this group of patients.