Small letter contrast sensitivity: an alternative measure of visual resolution for aviation candidates

Exceptional vision is needed to maintain high levels of aviation performance. Current standards for helicopter pilot training include superior visual acuity with minimal refractive error. Despite these demanding criteria, it is likely that visual ability varies among those who meet the standards for pilot training. A more complete knowledge of visual capabilities in these individuals will allow us to better correlate vision with performance and to develop more incisive criteria for selection. The purpose of this study was to investigate an alternative test of visual resolution for aviation candidates using small letter contrast sensitivity (SLCS). Computer-generated letter charts were used to measure visual acuity (VA) and SLCS in 16 candidates who had satisfied military vision standards for pilot training. The acuity and contrast charts varied, by line, in equal log steps such that the letter recognition task was comparable for the two types of measurement. VA and SLCS were highly correlated in these subjects, indicating that the two tests measure similar aspects of visual resolution. Scores were distributed across two lines on the acuity chart, but across four lines on the contrast chart, suggesting that SLCS offers a more discriminating test of resolution. This assumption was confirmed in that SLCS was more highly correlated with small amounts of refractive error in the candidates tested. SLCS offers a sensitive, adjunctive measure of visual resolution which may be useful for identifying the unique visual abilities required for aviation.     

扭力杆直径的优化设计

本文通过分析起动过程典型动荷类型的动态响应，在构造多目标优化问题数学模型的基础上，提出了选择扭力杆直径的新方法，并取得令人满意的结果，证明该方法可供设计扭力杆装置时直接引用。     

The partial testing design: a less costly way to test equivalence for sensitivity and specificity

We propose a new, less costly, design to test the equivalence of digital versus analogue mammography in terms of sensitivity and specificity. Because breast cancer is a rare event among asymptomatic women, the sample size for testing equivalence of sensitivity is larger than that for testing equivalence of specificity. Hence calculations of sample size are based on sensitivity. With the proposed design it is possible to achieve the same power as a completely paired design by increasing the number of less costly analogue mammograms and not giving the more expensive digital mammograms to some randomly selected subjects who are negative on the analogue mammogram. The key idea is that subjects who are negative on the analogue mammogram are unlikely to have cancer and hence contribute less information for estimating sensitivity than subjects who are positive on the analogue mammogram. To ascertain disease state among subjects not biopsied, we propose another analogue mammogram at a later time determined by a natural history model. The design differs from a double sampling design because it compares two imperfect tests instead of combining information from a perfect and imperfect test.     

An optimal design of a high strength,ductile metallic Material: Criteria and application to a α-titanium alloy

One means of optimizing high strength and high ductility in metals can be characterized on the basis of five criteria: a metastable, single-phase fcc or bc starting material; a low strain-hardening exponent and good workability; a low stacking-fault energy and high recovery temperature ; a hardening mechanism active below the recovery temperature ; and a low sensitivity of flow stress to temperature. By application of these criteria, thermo-mechanical processing of aβ-titanium alloy has resulted in a material with an ultimate tensile strength in excess of 320,000 psi with 15 pct RA, exhibiting ductile behavior at elastic strains greater than 2 pct.     

The Trimera mouse: generating human monoclonal antibodies and an animal model for human diseases

Monoclonal antibodies of human origin may have great therapeutic value in the treatment of cancer, autoimmune disorders and viral or bacterial infections. Several methods for generating human monoclonal antibodies exist; some are based on the transplantation of a functioning human immune system into severe combined immunodeficient (scid) mice or into Trimera mice, which are mice that have been lethally irradiated and radioprotected by transplantation of bone-marrow cells from scid mice. Trimera mice could be also used to develop animal models for human diseases by transplanting infected human tissue fragments and for creating models for cell therapy.     

The effects of overuse combined with intrinsic or extrinsic alterations in an animal model of rotator cuff tendinosis

An in vivo animal model was used to evaluate overuse and overuse plus intrinsic tendon injury or extrinsic tendon compression in the development of rotator cuff injury. Forty-four male Sprague-Dawley rats were divided into groups of 22. Each left shoulder received an intrinsic or extrinsic injury plus overuse (treadmill running), and each right shoulder received only overuse. Eleven rats from each group were sacrificed at 4 and 8 weeks. Supraspinatus tendons were evaluated histologically or geometrically and biomechanically. Ten rats constituted a cage-activity control group. Both supraspinatus tendons of the experimental groups had increases in cellularity and collagen disorganization and changes in cell shape compared with control tendons. Tendons with injury plus overuse exhibited a worse histologic grade than those with overuse alone. The cross-sectional area of both supraspinatus tendons of the experimental rats was significantly more than in control tendons. The area of the injury plus overuse tendons was increased on average compared with overuse-alone tendons. Biomechanically, the tissue moduli of overuse/intrinsic injury tendons at 4 weeks and those of the overuse/extrinsic injury tendons at 8 weeks were significantly lower than in control tendons. Tissue moduli of the overuse/injury tendons were significantly lower than in the overuse-alone tendons at 8 weeks. This study demonstrated that damage to the supraspinatus tendon can be caused by overuse and intrinsic injury, overuse and extrinsic compression, and overuse alone.     

Lay persons' sensitivity to statistical information: The case of high perceived applicability.

Six experimental studies were conducted to test the notion that lay persons are insensitive to statistical information when they are in the presence of individuating information allowing judgment by representativeness. Ss were 174 Israeli undergraduates and 259 members of the Israel Defense Forces. Two experiments examined the effects of reliability information on the regressiveness of predictions and on judgmental confidence. Two additional experiments examined the effects on confidence of informational redundancy. The final 2 studies examined Ss' capacity to reason in accordance with the notion of statistical information when its situational applicability is made apparent. On the basis of this and previous evidence, it is concluded that statistical rules seem to be used in accordance with the same rules that govern the use of nonstatistical rules, such as the "representativeness" rule and other rules of various contents. (23 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Vicryl-mesh wrap for the implantation of hydroxyapatite orbital implants: an animal model

OBJECTIVE: To evaluate host fibrovascularization of hydroxyapatite orbital implants wrapped in sclera or in Vicryl (polyglactin 910) mesh in a rabbit model. NUMBERS: Eight adult New Zealand white rabbits that received hydroxyapatite orbital implants wrapped in homologous donor sclera (four animals) or Vicryl mesh (four animals). INTERVENTIONS: The rabbits had one eye enucleated and then received a 12-mm hydroxyapatite implant wrapped in sclera or Vicryl mesh. Magnetic resonance imaging (MRI) and bone scintigraphy were done to assess host fibrovascularization of the implant 4, 8, 12 and 20 weeks after implantation. Two animals (one in each group) were killed at each of these times, and the implant was removed for histopathological examination. MAIN OUTCOME MEASURES: Enhancement on MRI, uptake on bone scintigraphy, fibrovascularization seen on histopathological examination. RESULTS: The degree of fibrovascularization was substantial in all the specimens but appeared greater in the Vicryl-mesh-wrapped implants in the first 12 weeks after implantation on both histopathological and MRI studies. At 20 weeks these findings were similar in the two groups. A granulomatous foreign-body giant-cell reaction to both the Vicryl mesh and the implant itself was present up to 8 weeks after implantation. Bone scans showed only grade 1+ activity in all the implants. CONCLUSIONS: Host fibrovascularization in the rabbit appears to occur to a greater degree in Vicryl-mesh-wrapped hydroxyapatite implants than in those wrapped in donor sclera during the first 12 weeks after implantation. Vicryl mesh appears to be an acceptable alternative wrap for the hydroxyapatite implant, eliminating the need for donor sclera and its potential risks of transmissible diseases.     

The limit of tactile spatial resolution in humans: grating orientation discrimination at the lip, tongue, and finger

The sensory neural pathways serving the lip, tongue, and finger are specialized for spatial information processing; thus, damage to these pathways is likely to be manifested most prominently as a loss of spatial acuity. For that reason, accurate measurement of spatial resolution at these regions is particularly important. The conventional test, the two-point discrimination task, does not measure the limit of spatial resolution and it yields variable results because it does not control nonspatial cues. The aim of this study was to quantify the limits of spatial resolution at the lip, tongue, and finger and to study the repeatability of those measurements using a stimulus that does not introduce nonspatial cues. We employed a grating orientation discrimination test, which has been studied extensively in relation to the underlying neural mechanisms. We obtained psychophysical thresholds for tactile spatial resolution from 15 normal, young adult subjects over seven test sessions. The finest gratings whose orientations were discriminated reliably had groove widths (gratings had equal groove and bar widths) that averaged 0.51 mm at the lip, 0.58 mm at the tongue, and 0.94 mm at the finger. These threshold measurements were highly reproducible between sessions with an overall improvement of 2% per session. These data suggest that the grating orientation discrimination task provides a stable, reliable measure of the human capacity for spatial resolution.     

Development of an induction melting process for materials with low electrical conductivity or high melting point

A hybrid process combining a cold crucible and a nontransferred plasma has been proposed. By using this process, not only metals with a high melting point but also dielectric materials can be melted without contamination. Also, good homogeneity of alloying elements can be expected by using this process because of the induction mixing taking place in the molten charge. By using the hybrid process, silicon was melted and held with almost no contact with the crucible. A heat-transfer analysis taking account of the dependence of electrical conductivity on temperature was performed on a silicon charge as a semiconductor. The effects of operating parameters, such as magnetic flux density, radius of the charge, and frequency of the coil current, were studied on the equilibrium temperature at which the heat generation rate in a charge balances with the heat removal rate. The critical temperature over which induction heating is possible was theoretically derived and was compared with the value obtained in an experiment. Formerly Undergraduate Student, Department of Materials Processing Engineering, Nagoya University     

Travelling through conformational space: an approach for analyzing the conformational behaviour of flexible molecules

The applications of the single-co-ordinate-driving (SCD) method in conformational analysis of flexible molecules have been discussed. SCD can best be characterised as travelling through low energy areas of the conformational space. It has been shown that SCD provides detailed information about the conformational behaviour of small and middle sized flexible molecules. It has been demonstrated that SCD may fail for molecules which are more rigid but still conformationally interesting, for example, AUG trimer of RNA. It has been found out that the search problems are eliminated when SCD is coupled with simulated annealing (SCD-SA). Both SCD and SCD-SA methods may be recognised as successful tools for analysis of conformational space. It has been demonstrated, how SCD and SCD-SA results can be used as a background to discover and analyse correlated conformational processes, to quantify molecular conformational flexibility, and to provide an appropriate background for an efficient free energy simulation.     

The gradient of spatial auditory attention in free field: an event-related potential study

Young adult subjects attended selectively to brief noise bursts delivered in free field via a horizontal array of seven loudspeakers spaced apart by 9 degrees of angle. Frequent "standard" stimuli (90%) and infrequent "target/deviant" stimuli (10%) of increased bandwidth were delivered at a fast rate in a random sequence equiprobably from each speaker. In separate runs, the subjects' task was to selectively attend to the leftmost, center, or rightmost speaker and to press a button to the infrequent "target" stimuli occurring at the designated spatial location. Behavioral detection rates and concurrently recorded event-related potentials (ERPs) indicated that auditory attention was deployed as a finely tuned gradient around the attended sound source, thus providing support for gradient models of auditory spatial attention. Furthermore, the ERP data suggested that the spatial focusing of attention was achieved in two distinct stages, with an early more broadly tuned filtering of inputs occurring over the first 80-200 msec after stimulus onset, followed by a more narrowly focused selection of attended-location deviants that began at around 250 msec and closely resembled the behavioral gradient of target detections.     

The search for predictors with high validity and low adverse impact: Compatible or incompatible goals?

Many researchers and personnel selection specialists appear to believe that validity must often be sacrificed to reduce adverse impact. This belief may be bolstered by an interpretation of the Uniform Guidelines on Employee Selection Procedures (Equal Employment Opportunity Commission, 1978) that alternative selection methods should be sought in an effort to reduce adverse impact as long as the accompanying reduction in validity is not too large. The authors show that, contrary to popular belief, within the universe of fair tests (as defined by T. A. Cleary, 1968), the most valid selection method will necessarily produce the least adverse impact. Although a less valid selection method can have less adverse impact than the most valid fair method, such an alternative necessarily fails to meet Cleary's fairness criterion. Thus, for fair tests, maximizing validity also minimizes adverse impact. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The augmentation of melanocytic nevi in guinea pigs by solar-simulated light: an animal model for human melanocytic nevi

Strong epidemiological evidence confirms the role of sunlight in human melanoma induction. Furthermore, the frequency of melanocytic nevi is a good indicator of future development of melanoma and a short-term marker of adverse reactions to melanoma-inducing sun exposure in humans. Thus, the aim of this study was to develop and define an animal model for sunlight-induced nevi that can be used as a surrogate model for sunlight-induced melanoma. Five treatment groups of 30-40 Hartley albino guinea pigs/group were treated with topical 7,12-dimethylbenzanthracene at a dose range of 6-240 mg on the dorsum of the skin. At week 20, half of the animals in each group were given a 12-month regimen of minimal erythemal solar-simulated light, 3 times/week, increased weekly to maintain erythema. These regimes induced epidermally derived pigmented melanocytic nevi clinically and histologically similar to human nevi (junctional, compound, and dermal). S100 and HMB45 staining was also consistent with the patterns seen in human nevi. In contrast to the high-dose 7,12-dimethylbenzanthracene-treated animals (60 and 240 mg), where solar-simulated light had no effect on nevi multiplicity, those groups treated with low doses (24, 12, and 6 mg) had a significant increase in nevi multiplicity after 12 months of solar-simulated light treatment (24 mg, 0.5 nevi/animal unirradiated versus 1.4 nevi/animal irradiated, P = 0.03; 12 mg, 0.2 unirradiated versus 1.2 irradiated, P = 0.02; 6 mg, 0 unirradiated versus 1.9 irradiated, P = 0.008). UVB-induced minimal erythemal dose was unaltered after exposure to photoreactivating light, consistent with the observation of others that placental mammals lack the DNA photolyase responsible for strong photoreactivation seen in nonplacental mammals and lower metazoans. Thus, our guinea pig model has some of the essential elements required to be a robust animal model for human nevi and a surrogate model for melanoma. These nevi are augmented by solar-simulated light, are histologically similar, occupy the same level within the skin, have the same natural history as human nevi, and are produced in an animal lacking strong photoreactivation. These features are not found in any previously described small laboratory animal model.     

The meaning of patient satisfaction: an explanation of high reported levels

The social policy background to the proliferation of patient satisfaction surveys is a desire for increased patient representation and participation. Within this context, it is assumed that satisfaction surveys embody patients' evaluations of services. However, as most surveys report high satisfaction levels, the interpretation of satisfaction as the outcome of an active evaluation has been called into question. The aim of this study is to identify whether and how service users evaluate services. This was made possible through unstructured in-depth interviews with users of mental health services and through more structured discussion around their responses on a patient satisfaction questionnaire (CSQ 18B) whose psychometric properties has been well documented. Twenty-nine people with current or recent contact with mental health services within the British National Health Service were interviewed. The data revealed that service users frequently described their experiences in positive or negative terms. However, the process by which these experiences were transformed into "evaluations" of the service was complex. Consequently, many expressions of "satisfaction" on the CSQ 18B hid a variety of reported negative experiences. An explanation for this lack of correspondence is outlined.     

Pharmacokinetic considerations in the design of optimal chemotherapeutic regimens for the treatment of breast carcinoma: a comceptual approach

Pharmacological data are currently available for a number of antineoplastic agents which have shown clinical activity in advanced breast carcincoma. Preclinical data reveal a relationship between therapeutic response and certain pharmacokinetic parameters such as time of effective cytotoxic exposure (Teff) and the product of concentration with time (Cxt). We have attempted to apply human pharmacologic data to get estimates of these parameters for 6 active agents in breast cancer, to relate them to response rates, and to suggest a method for estimating the role of individual drugs in a multidrug combination. The response rates for 6 single agents were obtained from literature review and related to estimates of Teff and Cxt. The Cxt-response relations for single drugs were linear for cyclophosphamide, 5-fluorouracil, and thiotepa; exponential for vincristine; and relatively flat for methotrexate and cytoxine arabinoside. Most Teff values for the active single agents clustered about 15 hr/dose. From the graphs of response rate vs Cxt, the individual contribution of each agent in a combination study was estimated to arrive at a predicted response rate. The predicted response rates for the combination studies correlated with the actual response rates determined in the clinical study, for 6 of 6 nonrandomized studies and for 12 of 14 randomized studies analyzed. In 2 studies, deviations from the predicted response rate were attributed to differences in study design or analysis. There was no correlation between Teff and predicted response rate. Analyses of pharmacokinetic data may be useful to simulate combination chemotherapy studies to predict the effectiveness of clinical trials in breast cancer. Since the pharmacologic data were not obtained for any of the agents in the actual clinical trials done, we can only speculate on the usefulness of this method. We would encourage the prospective collection of this data in future clinical trails.