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Selected AbstractsNoise-improved signal detection in cat primary visual cortex via a well-balanced stochastic resonance-like procedureEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 5 2007Klaus Funke Abstract Adding noise to a weak signal can paradoxically improve signal detection, a process called ,stochastic resonance' (SR). In the visual system, noise might be introduced by the image jitter resulting from high-frequency eye movements, like eye microtremor and microsaccades. To test whether this kind of noise might be beneficial or detrimental for cortical signal detection, we performed single-unit recordings from area 17 of anaesthetized cats while jittering the visual stimulus in a frequency and amplitude range resembling the possible range of eye movements. We used weak, sub- and peri-threshold visual stimuli, on top of which we superimposed noise with variable jitter amplitude. In accordance with the typical SR effect, we found that small noise levels actually increased the signal-to-noise ratio (SNR) of previously weak cortical visual responses, while originally strong responses were little affected or even reduced. Above a certain noise level, the SNR dropped a little, but not as a result of increased background activity , as would be proposed by SR theory , but because of a lowered response to signal and noise. Therefore, it seems that the ascending visual pathway optimally utilizes signal detection improvement by a SR-like process, while at the same time preventing spurious noise-induced activity and keeping the SNR sufficiently high. [source] A Self-Report Measure of Clinicians' Orientation toward Integrative MedicineHEALTH SERVICES RESEARCH, Issue 5p1 2005An-Fu Hsiao Objective. Patients in the U.S. often turn to complementary and alternative medicine (CAM) and may use it concurrently with conventional medicine to treat illness and promote wellness. However, clinicians vary in their openness to the merging of treatment paradigms. Because integration of CAM with conventional medicine can have important implications for health care, we developed a survey instrument to assess clinicians' orientation toward integrative medicine. Study Setting. A convenience sample of 294 acupuncturists, chiropractors, primary care physicians, and physician acupuncturists in academic and community settings in California. Data Collection Methods. We used a qualitative analysis of structured interviews to develop a conceptual model of integrative medicine at the provider level. Based on this conceptual model, we developed a 30-item survey (IM-30) to assess five domains of clinicians' orientation toward integrative medicine: openness, readiness to refer, learning from alternate paradigms, patient-centered care, and safety of integration. Principal Findings. Two hundred and two clinicians (69 percent response rate) returned the survey. The internal consistency reliability for the 30-item total scale and the five subscales ranged from 0.71 to 0.90. Item-scale correlations for the five subscales were higher for the hypothesized subscale than other subscales 75 percent or more of the time. Construct validity was supported by the association of the IM-30 total scale score (0,100 possible range, with a higher score indicative of greater orientation toward integrative medicine) with hypothesized constructs: physician acupuncturists scored higher than physicians (71 versus 50, p<.001), dual-trained practitioners scored higher than single-trained practitioners (71 versus 62, p<.001), and practitioners' self-perceived "integrativeness" was significantly correlated (r=0.60, p<.001) with the IM-30 total score. Conclusion. This study provides support for the reliability and validity of the IM-30 as a measure of clinicians' orientation toward integrative medicine. The IM-30 survey, which we estimate as requiring 5 minutes to complete, can be administered to both conventional and CAM clinicians. [source] Levels of comfort and ease among patients suffering from urinary incontinenceINTERNATIONAL JOURNAL OF UROLOGICAL NURSING, Issue 2 2007Michal Rassin Abstract Urinary incontinence is a common phenomenon among women, which harms social ties and is perceived as embarrassing and incurable. Despite its prevalence, there are few studies that have examined how those affected by this syndrome feel. The goal of this study was to examine the personal characteristics and levels of comfort among women suffering from urinary incontinence. The study included 50 women who had been diagnosed as suffering from urinary incontinence. The participants answered the Urinary Incontinence and Frequency Comfort Questionnaire, which examines levels of physical, mental, social and environmental comfort. , reliability has been found to be high in previous studies (,= 0·82). Our findings indicated that urinary incontinence occurred among the patients from several times a day to several times a week caused by sneezing, coughing and laughing. Most participants delayed treatment for up to 3 years. The general level of comfort was identified as medium low (SD = 0·04, M= 2·95) from a possible range of 1,6. Particularly low levels of comfort were recorded on items such as ,I feel clean and fresh,',finding a toilet in close proximity is a worrisome issue when I exit the house' and ,I fear having sex due to the urinary incontinence problem'. Identifying patients' needs and understanding their emotions are a useful basis for nursing intervention in promoting quality of life. [source] Molecular Contrast Optical Coherence Tomography: A Review,PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 2 2005Changhuei Yang ABSTRACT This article reviews the current state of research on the use of molecular contrast agents in optical coherence tomography (OCT) imaging techniques. After a brief discussion of the basic principle of OCT and the importance of incorporating molecular contrast agent usage into this imaging modality, we shall present an overview of the different molecular contrast OCT (MCOCT) methods that have been developed thus far. We will then discuss several important practical issues that define the possible range of contrast agent choice, the design criteria for engineered molecular contrast agent and the implementability of a given MCOCT method for clinical or biological applications. We will conclude by outlining a few areas of pursuit that deserve a greater degree of research and development. [source] Physiological and psychological symptoms of grief in widowsRESEARCH IN NURSING & HEALTH, Issue 1 2008Susan D. Kowalski Abstract In this cross-sectional descriptive survey of 173 widows, we describe their grief symptoms using an open-ended questionnaire and the Revised Grief Experience Inventory. Self-reported physical symptoms included pain, gastro-intestinal problems, medical/surgical conditions, sleep disturbances, and neurological/circulatory issues. Psychological symptoms were reported as depression, anxiety, and loneliness. The mean total grief score was 71.4,±,30.2 (possible range 22,132). Physical symptoms were significantly correlated with the total mean grief score, and subscales of physical distress, depression, existential tension, and guilt. When the subjects were grouped by years since loss, (range 1,5 years), there was no significant decrease found in overall grief scores, suggesting symptoms of grief experienced by widows may continue up to at least 5 years. © 2007 Wiley Periodicals, Inc. Res Nurs Health 31:23,30, 2008 [source] Optimal No-Arbitrage Bounds on S&P 500 Index Options and the Volatility SmileTHE JOURNAL OF FUTURES MARKETS, Issue 12 2001Patrick J. Dennis This article shows that the volatility smile is not necessarily inconsistent with the Black,Scholes analysis. Specifically, when transaction costs are present, the absence of arbitrage opportunities does not dictate that there exists a unique price for an option. Rather, there exists a range of prices within which the option's price may fall and still be consistent with the Black,Scholes arbitrage pricing argument. This article uses a linear program (LP) cast in a binomial framework to determine the smallest possible range of prices for Standard & Poor's 500 Index options that are consistent with no arbitrage in the presence of transaction costs. The LP method employs dynamic trading in the underlying and risk-free assets as well as fixed positions in other options that trade on the same underlying security. One-way transaction-cost levels on the index, inclusive of the bid,ask spread, would have to be below six basis points for deviations from Black,Scholes pricing to present an arbitrage opportunity. Monte Carlo simulations are employed to assess the hedging error induced with a 12-period binomial model to approximate a continuous-time geometric Brownian motion. Once the risk caused by the hedging error is accounted for, transaction costs have to be well below three basis points for the arbitrage opportunity to be profitable two times out of five. This analysis indicates that market prices that deviate from those given by a constant-volatility option model, such as the Black,Scholes model, can be consistent with the absence of arbitrage in the presence of transaction costs. © 2001 John Wiley & Sons, Inc. Jrl Fut Mark 21:1151,1179, 2001 [source] Postnatal development of synaptic transmission in local networks of L5A pyramidal neurons in rat somatosensory cortexTHE JOURNAL OF PHYSIOLOGY, Issue 1 2007Andreas Frick The probability of synaptic transmitter release determines the spread of excitation and the possible range of computations at unitary connections. To investigate whether synaptic properties between neocortical pyramidal neurons change during the assembly period of cortical circuits, whole-cell voltage recordings were made simultaneously from two layer 5A (L5A) pyramidal neurons within the cortical columns of rat barrel cortex. We found that synaptic transmission between L5A pyramidal neurons is very reliable between 2 and 3 weeks of postnatal development with a mean unitary EPSP amplitude of ,1.2 mV, but becomes less efficient and fails more frequently in the more mature cortex of ,4 weeks of age with a mean unitary EPSP amplitude of 0.65 mV. Coefficient of variation and failure rate increase as the unitary EPSP amplitude decreases during development. The paired-pulse ratio (PPR) of synaptic efficacy at 10 Hz changes from 0.7 to 1.04. Despite the overall increase in PPR, short-term plasticity displays a large variability at 4 weeks, ranging from strong depression to strong facilitation (PPR, range 0.6,2.1), suggesting the potential for use-dependent modifications at this intracortical synapse. In conclusion, the transmitter release probability at the L5A,L5A connection is developmentally regulated in such a way that in juvenile animals excitation by single action potentials is efficiently transmitted, whereas in the more mature cortex synapses might be endowed with a diversity of filtering characteristics. [source] Change in joint space width: Hyaline articular cartilage loss or alteration in meniscus?ARTHRITIS & RHEUMATISM, Issue 8 2006D. J. Hunter Objective To explore the relative contribution of hyaline cartilage morphologic features and the meniscus to the radiographic joint space. Methods The Boston Osteoarthritis of the Knee Study is a natural history study of symptomatic knee osteoarthritis (OA). Baseline and 30-month followup assessments included knee magnetic resonance imaging (MRI) and fluoroscopically positioned weight-bearing knee radiographs. Cartilage and meniscal degeneration were scored on MRI in the medial and lateral tibiofemoral joints using a semiquantitative grading system. Meniscal position was measured to the nearest millimeter. The dependent variable was joint space narrowing (JSN) on the plain radiograph (possible range 0,3). The predictor variables were MRI cartilage score, meniscal degeneration, and meniscal position measures. We first conducted a cross-sectional analysis using multivariate regression to determine the relative contribution of meniscal factors and cartilage morphologic features to JSN, adjusting for body mass index (BMI), age, and sex. The same approach was used for change in JSN and change in predictor variables. Results We evaluated 264 study participants with knee OA (mean age 66.7 years, 59% men, mean BMI 31.4 kg/m2). The results from the models demonstrated that meniscal position and meniscal degeneration each contributed to prediction of JSN, in addition to the contribution by cartilage morphologic features. For change in medial joint space, both change in meniscal position and change in articular cartilage score contributed substantially to narrowing of the joint space. Conclusion The meniscus (both its position and degeneration) accounts for a substantial proportion of the variance explained in JSN, and the change in meniscal position accounts for a substantial proportion of change in JSN. [source] Measuring disease activity and functional status in patients with scleroderma and Raynaud's phenomenonARTHRITIS & RHEUMATISM, Issue 9 2002Peter A. Merkel Objective To document disease activity and functional status in patients with scleroderma (systemic sclerosis [SSc]) and Raynaud's phenomenon (RP) and to determine the sensitivity to change, reliability, ease of use, and validity of various outcome measures in these patients. Methods Patients with SSc and moderate-to-severe RP participating in a multicenter RP treatment trial completed daily diaries documenting the frequency and duration of RP attacks and recorded a daily Raynaud's Condition Score (RCS). Mean scores for the 2-week periods prior to baseline (week 0), end of trial (week 6), and posttrial followup (week 12) were calculated. At weeks 0, 6, and 12, physicians completed 3 global assessment scales and performed clinical assessments of digital ulcers and infarcts; patients completed the Health Assessment Questionnaire (HAQ), the Arthritis Impact Measurement Scales 2 (AIMS2) mood and tension subscales, 5 specific SSc/RP-related visual analog scales (VAS), and 3 other VAS global assessments. We used these measures to document baseline disease activity and to assess their construct validity, sensitivity to change, and reliability in trial data. Results Two hundred eighty-one patients (248 women, 33 men; mean age 50.4 years [range 18,82 years]) from 14 centers participated. Forty-eight percent had limited cutaneous SSc; 52% had diffuse cutaneous SSc. Fifty-nine patients (21%) had digital ulcers at baseline. Patients had 3.89 ± 2.33 (mean ± SD) daily RP attacks (range 0.8,14.6), with a duration of 82.1 ± 91.6 minutes/attack. RCS for RP activity (possible range 0,10) was 4.30 ± 1.92. HAQ scores (0,3 scale) indicated substantial disability at baseline (total disability 0.86, pain 1.19), especially among the subscales pertaining to hand function (grip, eating, dressing). AIMS2 mood and tension scores were fairly high, as were many of the VAS scores. Patients with digital ulcers had worse RCS, pain, HAQ disability (overall, grip, eating, and dressing), physician's global assessment, and tension, but no significant difference in the frequency of RP, duration of RP, patient's global assessment, or mood, compared with patients without digital ulcers. VAS scores for digital ulcers as rated by the patients were not consistent with the physician's ratings. Factor analysis of the 18 measures showed strong associations among variables in 4 distinct domains: disease activity, RP measures, digital ulcer measures, and mood/tension. Reliability of the RCS, HAQ pain and disability scales, and AIMS2 mood and tension subscales was high. The RP measures demonstrated good sensitivity to change (effect sizes 0.33,0.76). Conclusion Our findings demonstrate that the significant activity, disability, pain, and psychological impact of RP and digital ulcers in SSc can be measured by a small set of valid and reliable outcome measures. These outcome measures provide information beyond the quantitative metrics of RP attacks. We propose a core set of measures for use in clinical trials of RP in SSc patients that includes the RCS, patient and physician VAS ratings of RP activity, a digital ulcer/infarct measure, measures of disability and pain (HAQ), and measures of psychological function (AIMS2). [source] How well does the finite Fourier transform approximate the Fourier transform?,COMMUNICATIONS ON PURE & APPLIED MATHEMATICS, Issue 10 2005Charles L. Epstein We show that the answer to the question in the title is "very well indeed." In particular, we prove that, throughout the maximum possible range, the finite Fourier coefficients provide a good approximation to the Fourier coefficients of a piecewise continuous function. For a continuous periodic function, the size of the error is estimated in terms of the modulus of continuity of the function. The estimates improve commensurately as the functions become smoother. We also show that the partial sums of the finite Fourier transform provide essentially as good an approximation to the function and its derivatives as the partial sums of the ordinary Fourier series. Along the way we establish analogues of the Riemann-Lebesgue lemma and the localization principle. © 2004 Wiley Periodicals, Inc. [source] Mantophasmatodea and phylogeny of the lower neopterous insectsCLADISTICS, Issue 3 2005Matthew D. Terry Polyneoptera is a name sometimes applied to an assemblage of 11 insect orders comprising the lower neopterous or "orthopteroid" insects. These orders include familiar insects such as Orthoptera (grasshoppers), Blattodea (roaches), Isoptera (termites) (Mantodea) praying mantises, Dermaptera (earwigs), Phasmatodea (stick insects), Plecoptera (stoneflies), as well as the more obscure, Embiidina (web-spinners), Zoraptera (angel insects) and Grylloblattodea (ice-crawlers). Many of these insect orders exhibit a high degree of morphological specialization, a condition that has led to multiple phylogenetic hypotheses and little consensus among investigators. We present a phylogenetic analysis of the polyneopteran orders representing a broad range of their phylogenetic diversity and including the recently described Mantophasmatodea. These analyses are based on complete 18S rDNA, 28S rDNA, Histone 3 DNA sequences, and a previously published morphology matrix coded at the ordinal level. Extensive analyses utilizing different alignment methodologies and parameter values across a majority of possible ranges were employed to test for sensitivity of the results to ribosomal alignment and to explore patterns across the theoretical alignment landscape. Multiple methodologies support the paraphyly of Polyneoptera, the monophyly of Dictyoptera, Orthopteroidea (sensu Kukalova-Peck; i.e. Orthoptera + Phasmatodea + Embiidina), and a group composed of Plecoptera + Dermaptera + Zoraptera. Sister taxon relationships between Embiidina + Phasmatodea in a group called "Eukinolabia", and Dermaptera + Zoraptera ("Haplocercata") are also supported by multiple analyses. This analysis also supports a sister taxon relationship between the newly described Mantophasmatodea, which are endemic to arid portions of southern Africa, and Grylloblattodea, a small order of cryophilic insects confined to the north-western Americas and north-eastern Asia, in a group termed "Xenonomia". This placement, coupled with the morphological disparity of the two groups, validates the ordinal status of Mantophasmatodea. © The Willi Hennig Society 2005. [source] | |||||||||||||