Showing papers by "Boston University published in 1997"
TL;DR: The APOE∈4 allele represents a major risk factor for AD in all ethnic groups studied, across all ages between 40 and 90 years, and in both men and women.
Abstract: Objective. —To examine more closely the association between apolipoprotein E (APOE) genotype and Alzheimer disease (AD) by age and sex in populations of various ethnic and racial denominations. Data Sources. —Forty research teams contributed data onAPOEgenotype, sex, age at disease onset, and ethnic background for 5930 patients who met criteria for probable or definite AD and 8607 controls without dementia who were recruited from clinical, community, and brain bank sources. Main Outcome Measures. —Odds ratios (ORs) and 95% confidence intervals (Cls) for AD, adjusted for age and study and stratified by major ethnic group (Caucasian, African American, Hispanic, and Japanese) and source, were computed forAPOEgenotypes ∈2/∈2,∈2/∈3,∈2/∈4,∈3/∈4 and ∈4/∈4 relative to the ∈3/∈3 group. The influence of age and sex on the OR for each genotype was assessed using logistic regression procedures. Results. —Among Caucasian subjects from clinic- or autopsy-based studies, the risk of AD was significantly increased for people with genotypes ∈2/∈4 (OR=2.6, 95% Cl=1.6-4.0), ∈3/∈4 (OR=3.2, 95% Cl=2.8-3.8), and ∈4/∈4 (OR=14.9, 95% CI=10.8-20.6); whereas, the ORs were decreased for people with genotypes ∈2/∈2 (OR=0.6, 95% Cl=0.2-2.0) and ∈2/∈3 (OR=0.6, 95% Cl=0.5-0.8). TheAPOE∈4-AD association was weaker among African Americans and Hispanics, but there was significant heterogeneity in ORs among studies of African Americans (P Conclusions. —TheAPOE∈4 allele represents a major risk factor for AD in all ethnic groups studied, across all ages between 40 and 90 years, and in both men and women. The association betweenAPOE∈4 and AD in African Americans requires clarification, and the attenuated effect ofAPOE∈4 in Hispanics should be investigated further.
3,825 citations
TL;DR: In this paper, the authors present evidence from satellite data that the photosynthetic activity of terrestrial vegetation increased from 1981 to 1991 in a manner that is suggestive of an increase in plant growth associated with a lengthening of the active growing season.
Abstract: Variations in the amplitude and timing of the seasonal cycle of atmospheric CO2 have shown an association with surface air temperature consistent with the hypothesis that warmer temperatures have promoted increases in plant growth during summer1 and/or plant respiration during winter2 in the northern high latitudes. Here we present evidence from satellite data that the photosynthetic activity of terrestrial vegetation increased from 1981 to 1991 in a manner that is suggestive of an increase in plant growth associated with a lengthening of the active growing season. The regions exhibiting the greatest increase lie between 45°N and 70°N, where marked warming has occurred in the spring time3 due to an early disappearance of snow4. The satellite data are concordant with an increase in the amplitude of the seasonal cycle of atmospheric carbon dioxide exceeding 20% since the early 1970s, and an advance of up to seven days in the timing of the drawdown of CO2 in spring and early summer1. Thus, both the satellite data and the CO2 record indicate that the global carbon cycle has responded to interannual fluctuations in surface air temperature which, although small at the global scale, are regionally highly significant.
3,368 citations
TL;DR: It is shown that the self-similarity in WWW traffic can be explained based on the underlying distributions of WWW document sizes, the effects of caching and user preference in file transfer, the effect of user "think time", and the superimposition of many such transfers in a local-area network.
Abstract: The notion of self-similarity has been shown to apply to wide-area and local-area network traffic. We show evidence that the subset of network traffic that is due to World Wide Web (WWW) transfers can show characteristics that are consistent with self-similarity, and we present a hypothesized explanation for that self-similarity. Using a set of traces of actual user executions of NCSA Mosaic, we examine the dependence structure of WWW traffic. First, we show evidence that WWW traffic exhibits behavior that is consistent with self-similar traffic models. Then we show that the self-similarity in such traffic can be explained based on the underlying distributions of WWW document sizes, the effects of caching and user preference in file transfer, the effect of user "think time", and the superimposition of many such transfers in a local-area network. To do this, we rely on empirically measured distributions both from client traces and from data independently collected at WWW servers.
2,608 citations
TL;DR: This paper extended earlier research concerning the relationship between corporate social performance and corporate financial performance, with particular emphasis on methodological inconsistencie... and showed that methodological inconsistency is a major obstacle in the analysis.
Abstract: This article extends earlier research concerning the relationship between corporate social performance and corporate financial performance, with particular emphasis on methodological inconsistencie...
1,929 citations
TL;DR: Women with lupus in the 35- to 44-year age group were over 50 times more likely to have a myocardial infarction than were women of similar age in the Framingham Offspring Study.
Abstract: The authors ascertained cardiovascular events (myocardial infarction and angina pectoris) in 498 women with systemic lupus erythematosus seen at the University of Pittsburgh Medical Center from 1980 to 1993 (3,522 person-years). Subjects were stratified by age, and cardiovascular event incidence rates were determined. The authors compared these rates with cardiovascular event rates were determined. The authors compared these rates with cardiovascular event rates occurring over the same time period in 2,208 women of similar age participating in the Framingham Offspring Study (17,519 person-years). Age-specific rate ratios were computed to determine whether the cardiovascular events in the lupus cohort were greater than expected. The risk factors associated with cardiovascular events in women with lupus were determined. There were 33 first events (11 myocardial infarction, 10 angina pectoris, and 12 both angina pectoris and myocardial infarction) after the diagnosis of lupus: two thirds were under the age of 55 years at the time of event. Women with lupus in the 35- to 44-year age group were over 50 times more likely to have a myocardial infarction than were women of similar age in the Framingham Offspring Study (rate ratio = 52.43, 95% confidence interval 21.6-98.5). Older age at lupus diagnosis, longer lupus disease duration, longer duration of corticosteroid use, hypercholesterolemia, and postmenopausal status were more common in the women with lupus who had a cardiovascular event than in those who did not have an event. Premature cardiovascular disease is much more common in young premenopausal women with lupus than in a population sample. With the increased life expectancy of lupus patients due to improved therapy, cardiovascular disease has emerged as a significant threat to the health of these women. The impact of this problem has been underrecognized, with little focus placed on aggressive management of hypercholesterolemia and other possible risk factors.
1,689 citations
TL;DR: The effects on brain function associated with prenatal methylmercury exposure therefore appear widespread, and early dysfunction is detectable at exposure levels currently considered safe.
1,682 citations
TL;DR: The psychometric properties of the Depression Anxiety Stress Scales were evaluated in two studies using large clinical samples and indicated that the DASS distinguished various anxiety and mood disorder groups in the predicted direction.
1,629 citations
TL;DR: In this article, the authors provide a plausible physical explanation for the occurrence of self-similarity in local-area network (LAN) traffic, based on convergence results for processes that exhibit high variability and is supported by detailed statistical analyzes of real-time traffic measurements from Ethernet LANs at the level of individual sources.
Abstract: A number of empirical studies of traffic measurements from a variety of working packet networks have demonstrated that actual network traffic is self-similar or long-range dependent in nature-in sharp contrast to commonly made traffic modeling assumptions. We provide a plausible physical explanation for the occurrence of self-similarity in local-area network (LAN) traffic. Our explanation is based on convergence results for processes that exhibit high variability and is supported by detailed statistical analyzes of real-time traffic measurements from Ethernet LANs at the level of individual sources. This paper is an extended version of Willinger et al. (1995). We develop here the mathematical results concerning the superposition of strictly alternating ON/OFF sources. Our key mathematical result states that the superposition of many ON/OFF sources (also known as packet-trains) with strictly alternating ON- and OFF-periods and whose ON-periods or OFF-periods exhibit the Noah effect produces aggregate network traffic that exhibits the Joseph effect. There is, moreover, a simple relation between the parameters describing the intensities of the Noah effect (high variability) and the Joseph effect (self-similarity). An extensive statistical analysis of high time-resolution Ethernet LAN traffic traces confirms that the data at the level of individual sources or source-destination pairs are consistent with the Noah effect. We also discuss implications of this simple physical explanation for the presence of self-similar traffic patterns in modern high-speed network traffic.
1,593 citations
TL;DR: This work presents several types of decision tree classification algorithms and shows that decision trees have several advantages for remote sensing applications by virtue of their relatively simple, explicit, and intuitive classification structure.
1,419 citations
TL;DR: There is evidence that plaque stability, vasomotor function, and the tendency to thrombosis are subject to modification by specific antioxidants, and it is speculated that these mechanisms have an important role in the benefits of antioxidants.
Abstract: Epidemiologic studies have demonstrated an association between increased intake of antioxidant vitamins such as vitamin E and vitamin C and reduced morbidity and mortality from coronary artery disease. This association has been explained on the basis of the “oxidative-modification hypothesis” of atherosclerosis, which proposes that atherogenesis is initiated by oxidation of the lipids in low-density lipoprotein (LDL), also termed lipid peroxidation. As a corollary to this hypothesis, antioxidants that inhibit lipid peroxidation in LDL should limit atherosclerosis and its clinical manifestations, such as myocardial infarction and stroke. In this review, we will evaluate the current literature involving antioxidants and vascular . . .
1,395 citations
TL;DR: In this paper, the authors describe the key features of the new synthesis and its implications for the role of monetary policy and find that the New Neoclassical Synthesis rationalizes an activist monetary policy which is a simply system of inflation targets.
Abstract: Macroeconomics is moving toward a New Neoclassical Synthesis, which like the synthesis of the 1960s melds Classical with Keynesian ideas. This paper describes the key features of the new synthesis and its implications for the role of monetary policy. We find that the New Neoclassical Synthesis rationalizes an activist monetary policy which is a simply system of inflation targets. Under this "neutral" monetary policy, real quantities evolve as suggested in the literature on real business cycles. Going beyond broad principles, we use the new synthesis to address several operational aspects of inflation targeting. These include its practicality, the response to oil shocks, the choice of price index, the design of a mandate, and the tactics of interest rate policy.
TL;DR: Amyloidosis is not a single disease but a term for diseases that share a common feature: the extracellular deposition of pathologic insoluble fibrillar proteins in organs and tissues.
Abstract: Amyloidosis is not a single disease but a term for diseases that share a common feature: the extracellular deposition of pathologic insoluble fibrillar proteins in organs and tissues. In the mid-19th century, Virchow adopted the botanical term “amyloid,” meaning starch or cellulose, to describe abnormal extracellular material seen in the liver at autopsy.1 Subsequently, amyloid was found to stain with Congo red, appearing red microscopically in normal light but apple green when viewed in polarized light.2,3 Almost a century after Virchow's observations, the fibrillar nature of amyloid was described with the use of electron microscopy and the characteristic beta-pleated–sheet . . .
TL;DR: Use of a uniform definition of improvement will help standardize the conduct and reporting of clinical trials, and should help practitioners decide if a child with JA has responded adequately to therapy.
Abstract: Objective. To identify a core set of outcome variables for the assessment of children with juvenile arthritis (JA), to use the core set to develop a definition of improvement to determine whether individual patients demonstrate clinically important improvement, and to promote this definition as a single efficacy measure in JA clinical trials.
Methods. A core set of outcome variables was established using a combination of statistical and consensus formation techniques. Variables in the core set consisted of 1) physician global assessment of disease activity; 2) parent/patient assessment of overall well-being; 3) functional ability; 4) number of joints with active arthritis; 5) number of joints with limited range of motion; and 6) erythrocyte sedimentation rate. To establish a definition of improvement using this core set, 21 pediatric rheumatologists from 14 countries met, and, using consensus formation techniques, scored each of 72 patient profiles as improved or not improved. Using the physicians' consensus as the gold standard, the chi-square, sensitivity, and specificity were calculated for each of 240 possible definitions of improvement. Definitions with sensitivity or specificity of <80% were eliminated. The ability of the remaining definitions to discriminate between the effects of active agent and those of placebo, using actual trial data, was then observed. Each definition was also ranked for face validity, and the sum of the ranks was then multiplied by the kappa statistic.
Results. The definition of improvement with the highest final score was as follows: at least 30% improvement from baseline in 3 of any 6 variables in the core set, with no more than 1 of the remaining variables worsening by >30%. The second highest scoring definition was closely related to the first; the third highest was similar to the Paulus criteria used in adult rheumatoid arthritis trials, except with different variables. This indicates convergent validity of the process used.
Conclusion. We propose a definition of improvement for JA. Use of a uniform definition will help standardize the conduct and reporting of clinical trials, and should help practitioners decide if a child with JA has responded adequately to therapy. We are in the process of prospectively validating this definition and several others that scored highly.
TL;DR: The study provides sufficient statistical power for assessing OSA and other SDB as risk factors for major cardiovascular events, including myocardial infarction and stroke.
Abstract: The Sleep Heart Health Study (SHHS) is a prospective cohort study designed to investigate obstructive sleep apnea (OSA) and other sleep-disordered breathing (SDB) as risk factors for the development of cardiovascular disease. The study is designed to enroll 6,600 adult participants aged 40 years and older who will undergo a home polysomnogram to assess the presence of OSA and other SDB. Participants in SHHS have been recruited from cohort studies in progress. Therefore, SHHS adds the assessment of OSA to the protocols of these studies and will use already collected data on the principal risk factors for cardiovascular disease as well as follow-up and outcome information pertaining to cardiovascular disease. Parent cohort studies and recruitment targets for these cohorts are the following: Atherosclerosis Risk in Communities Study (1,750 participants), Cardiovascular Health Study (1,350 participants), Framingham Heart Study (1,000 participants), Strong Heart Study (600 participants), New York Hypertension Cohorts (1,000 participants), and Tucson Epidemiologic Study of Airways Obstructive Diseases and the Health and Environment Study (900 participants). As part of the parent study follow-up procedures, participants will be surveyed at periodic intervals for the incidence and recurrence of cardiovascular disease events. The study provides sufficient statistical power for assessing OSA and other SDB as risk factors for major cardiovascular events, including myocardial infarction and stroke.
TL;DR: A simple method for the estimation of global leaf area index (LAI) and fraction of photosynthetically active radiation absorbed by the vegetation (FAPAR) from atmospherically corrected Normalized Difference Vegetation Index (NDVI) observations is described.
Abstract: A simple method for the estimation of global leaf area index (LAI) and fraction of photosynthetically active radiation absorbed by the vegetation (FAPAR) from atmospherically corrected Normalized Difference Vegetation Index (NDVI) observations is described. Recent improvements to the authors' three dimensional radiative transfer model of a vegetated surface are described. Example simulation results and a validation exercise are discussed. The model was utilized to derive land cover specific NDVI-LAI and NDVI-FAPAR relations. The method therefore requires stratification of global vegetation into cover types that are compatible with the radiative transfer model. Such a classification based on vegetation structure is proposed and a simple method for its derivation is presented. Proof-of-concept results are given to illustrate the feasibility of the proposed method.
Smith College1, Boston University2, University of California, San Diego3, University of Savoy4, University of Illinois at Chicago5, University of New Brunswick6, Claude Bernard University Lyon 17, Icahn School of Medicine at Mount Sinai8, University of Amsterdam9, University of Pennsylvania10, University of Newcastle11, Drexel University12, Laval University13, Duke University14, Fordham University15, McGill University16, University of Waterloo17, University of British Columbia18, University of Bath19, University of Padua20, University of Florence21, University of Michigan22
TL;DR: In this article, the authors describe the progress of an international group of investigators who have commenced a coordinated effort to develop a standardized set of cognitive measures for obsessive-compulsive disorder.
TL;DR: It is demonstrated that strike-interval fluctuations are more random (i.e., less correlated) in elderly subjects and in subjects with Huntington's disease, which are apparently associated with changes in central nervous system control.
Abstract: Fluctuations in the duration of the gait cycle (the stride interval) display fractal dynamics and long-range correlations in healthy young adults. We hypothesized that these stride-interval correlations would be altered by changes in neurological function associated with aging and certain disease states. To test this hypothesis, we compared the stride-interval time series of 1) healthy elderly subjects and young controls and of 2) subjects with Huntington's disease and healthy controls. Using detrended fluctuation analysis we computed alpha, a measure of the degree to which one stride interval is correlated with previous and subsequent intervals over different time scales. The scaling exponent alpha was significantly lower in elderly subjects compared with young subjects (elderly: 0.68 +/- 0.14; young: 0.87 +/- 0.15; P < 0.003). The scaling exponent alpha was also smaller in the subjects with Huntington's disease compared with disease-free controls (Huntington's disease: 0.60 +/- 0.24; controls: 0.88 +/-0.17; P < 0.005). Moreover, alpha was linearly related to degree of functional impairment in subjects with Huntington's disease (r = 0.78, P < 0.0005). These findings demonstrate that strike-interval fluctuations are more random (i.e., less correlated) in elderly subjects and in subjects with Huntington's disease. Abnormal alterations in the fractal properties of gait dynamics are apparently associated with changes in central nervous system control.
TL;DR: In this paper, the authors propose a holistic framework to examine several constructs suggested in the literature that lead to the behavioral intention to use an information system, including situational involvement, intrinsic involvement, argument for change, perceived usefulness, ease of use, prior usage, and attitude constructs.
Abstract: Organizational investment in information systems is often large and risky given the variety of information requirements placed on systems today. To make more informed decisions and to meet the challenge of developing systems that satisfy these demands, system developers need to achieve a better understanding of factors that ultimately lead to system usage. To enhance this understanding, we posit a holistic framework to examine several constructs suggested in the literature that lead to the behavioral intention to use an information system. Our framework includes situational involvement, intrinsic involvement, argument for change, perceived usefulness, ease of use, prior usage, and attitude constructs. We extend the Davis, Bagozzi, and Warshaw Technology Acceptance Model (TAM), which is founded on the Theory of Reasoned Action. A diverse sample from industry is used to test our model. Structural equation modeling is used to examine the entire pattern of intercorrelations among the constructs and to test related propositions. A hierarchical structure is used to compare the explanatory ability of TAM with our extension. Our model explains a large portion of the covariance among the constructs that lead to a user's behavioral intention to use an information system and compares favorably with TAM. The results indicate that (1) the direct effect of situational involvement on behavioral intention as well as attitude is significant in the negative direction, (2) attitude seems to play a mediating role, and (3) intrinsic involvement plays a significant role in shaping perceptions. Finally, we conclude that the user involvement construct needs to be separated into its psychological as well as its participative components for developers to understand its impact on the systems development process.
01 Apr 1997
TL;DR: The superposition of many ON/OFF sources with strictly alternating ON- and OFF-periods can produce aggregate network traffic that exhibits the Joseph Effect, and this mathematical result can be combined with modern high-performance computing capabilities to yield a simple and efficient linear-time algorithm for generating self-similar traffic traces.
Abstract: We state and prove the following key mathematical result in self-similar traffic modeling: the superposition of many ON/OFF sources (also known as packet trains) with strictly alternating ON- and OFF-periods and whose ON-periods or OFF-periods exhibit the Noah Effect (i.e., have high variability or infinite variance) can produce aggregate network traffic that exhibits the Joseph Effect (i.e., is self-similar or long-range dependent). There is, moreover, a simple relation between the parameters describing the intensities of the Noah Effect (high variability) and the Joseph Effect (self-similarity). This provides a simple physical explanation for the presence of self-similar traffic patterns in modern high-speed network traffic that is consistent with traffic measurements at the source level. We illustrate how this mathematical result can be combined with modern high-performance computing capabilities to yield a simple and efficient linear-time algorithm for generating self-similar traffic traces.We also show how to obtain in the limit a Levy stable motion, that is, a process with stationary and independent increments but with infinite variance marginals. While we have presently no empirical evidence that such a limit is consistent with measured network traffic, the result might prove relevant for some future networking scenarios.
TL;DR: Elderly persons at high risk of developing radiographic knee OA included obese persons, nonsmokers, and those who were physically active and factors not associated with the risk of OA including chondrocalcinosis and a history of hand OA.
Abstract: Objective. Knee osteoarthritis (OA) is highly prevalent, especially in the elderly. Preventive strategies require a knowledge of risk factors that precede disease onset. The present study was conducted to determine the longitudinal risk factors for knee OA in an elderly population.
Methods. A longitudinal study of knee OA involving members of the Framingham Study cohort was performed. Weight-bearing knee radiographs were obtained in 1983–1985 (baseline) and again in 1992–1993. Incident disease was defined as the occurrence of new radiographic OA (Kellgren and Lawrence grade ⩾2 on a 0–4 scale) in those without radiographic OA at baseline. Risk factors assessed at baseline and in the interim were tested in univariate and multivariate equations to evaluate their association with incident knee OA.
Results. Of 598 patients without knee OA at baseline (mean age 70.5 years, 63.7% women), 93 (15.6%) developed OA. After adjustment for multiple risk factors, women had a higher risk of OA than did men (adjusted odds ratio [OR] = 1.8, 95% confidence interval [95% CI] 1.1–3.1). Higher baseline body mass index increased the risk of OA (OR = 1.6 per 5-unit increase, 95% CI 1.2–2.2), and weight change was directly correlated with the risk of OA (OR = 1.4 per 10-lb change in weight, 95% CI 1.1–1.8). Physical activity increased the risk of OA (for those in the highest quartile, OR = 3.3, 95% CI 1.4–7.5). Smokers had a lower risk than did nonsmokers (for those who smoked an average of ⩾10 cigarettes/day, OR = 0.4, 95% CI 0.2–0.8). Factors not associated with the risk of OA included chondrocalcinosis and a history of hand OA. Weight-related factors affected the risk of OA only in women.
Conclusion. Elderly persons at high risk of developing radiographic knee OA included obese persons, nonsmokers, and those who were physically active. The direction of weight change correlated directly with the risk of developing OA.
TL;DR: Aberrant nuclear expression of NF-kappaB/Rel may play a role in tumor progression, and represents a possible therapeutic target in the treatment of these tumors.
Abstract: Expression of nuclear factor-kappaB (NF-kappaB)/Rel transcription factors has recently been found to promote cell survival, inhibiting the induction of apoptosis. In most cells other than B lymphocytes, NF-kappaB/Rel is inactive, sequestered in the cytoplasm. For example, nuclear extracts from two human untransformed breast epithelial cell lines expressed only very low levels of NF-kappaB. Unexpectedly, nuclear extracts from two human breast tumor cell lines displayed significant levels of NF-kappaB/Rel. Direct inhibition of this NF-kappaB/ Rel activity in breast cancer cells induced apoptosis. High levels of NF-kappaB/Rel binding were also observed in carcinogen-induced primary rat mammary tumors, whereas only expectedly low levels were seen in normal rat mammary glands. Furthermore, multiple human breast cancer specimens contained significant levels of nuclear NF-kappaB/Rel subunits. Thus, aberrant nuclear expression of NF-kappaB/Rel is associated with breast cancer. Given the role of NF-kappaB/Rel factors in cell survival, this aberrant activity may play a role in tumor progression, and represents a possible therapeutic target in the treatment of these tumors.
University of Tennessee Health Science Center1, University of Louisville2, Pennsylvania State University3, Houston Methodist Hospital4, University of Kentucky5, Erie County Medical Center6, University of Arkansas at Little Rock7, University of Cincinnati8, University of California, Davis9, Ohio State University10, Harvard University11, St. John's Hospital12, University of California, San Diego13, Vanderbilt University14, MedStar Washington Hospital Center15, University Medical Center16, University of South Carolina17, Allegheny General Hospital18, Baylor College of Medicine19, University of Southern California20, Wright State University21, University of Western Ontario22, University of Alberta23, Gundersen Health System24, Medical College of Wisconsin25, Dartmouth College26, Boston University27, Sparrow Health System28, State University of New York Upstate Medical University29, Saint Louis University30, University of Missouri31, University of Texas Medical Branch32, University of North Carolina at Chapel Hill33, Mayo Clinic34, Carolinas Medical Center35, Cedars-Sinai Medical Center36, Rutgers University37, Henry Ford Health System38, University of Manitoba39, University of Texas Southwestern Medical Center40, University of California, San Francisco41, University of South Alabama42, University of Tennessee43
TL;DR: Although newer diagnostic techniques are being applied, at this time aortography remains the diagnostic standard; bypass techniques, which provide distal aortic perfusion, produced significantly lower paraplegia rates than the clamp and sew approach.
Abstract: Background: Blunt aortic injury is a major cause of death from blunt trauma. Evolution of diagnostic techniques and methods of operative repair have altered the management and posed new questions in recent years. Methods: This study was a prospectively conducted multicenter trial involving 50 trauma centers in North America under the direction of the Multi-institutional Trial Committee of the American Association for the Surgery of Trauma. Results: There were 274 blunt aortic injury cases studied over 2.5 years, of which 81% were caused by automobile crashes. Chest computed tomography and transesophageal echocardiography were applied in 88 and 30 cases, respectively, and were 75 and 80% diagnostic, respectively. Two hundred seven stable patients underwent planned thoracotomy and repair. Clamp and sew technique was used in 73 (35%) and bypass techniques in 134 (65%). Overall mortality was 31%, with 63% of deaths being attributable to aortic rupture; mortality was not affected by method of repair. Paraplegia occurred postoperatively in 8.7%. Logistic regression analysis demonstrated clamp and sew (p = 0.002) and aortic cross clamp time of 30 minutes (p = 0.01) to be associated with development of postoperative paraplegia. Conclusions: Rupture after hospital admission remains a major problem. Although newer diagnostic techniques are being applied, at this time aortography remains the diagnostic standard. Aortic cross clamp time beyond 30 minutes was associated with paraplegia; bypass techniques, which provide distal aortic perfusion, produced significantly lower paraplegia rates than the clamp and sew approach.
TL;DR: A scale to measure the personal construct of empowerment as defined by consumers of mental health services was developed and field tested and demonstrated adequate internal consistency and some evidence for validity.
Abstract: Objective A scale to measure the personal construct of empowerment as defined by consumers of mental health services was developed and field tested. Methods After extensive development, pilot testing, and analyses, a 28-item scale to measure empowerment was tested on 271 members of six self-help programs in six states. Factor analyses were used to identify the underlying dimensions of empowerment. To establish the scale's reliability and validity, responses were factor analyzed, and other analyses were conducted. Results Analyses revealed five factors: self-efficacy-self-esteem, power-powerlessness, community activism, righteous anger, and optimism-control over the future. Empowerment was related to quality of life and income but not to the demographic variables of age, gender, ethnicity, marital status, education level, or employment status. Empowerment was inversely related to use of traditional mental health services and positively related to community activism. Conclusions The findings set a framework for a clearer understanding of the imprecise and overused concept of empowerment. The scale demonstrated adequate internal consistency and some evidence for validity. Further testing must be done to establish whether it has discriminant validity and is sensitive to change.
TL;DR: The neural circuitry postulated to subserve the cerebellar contribution to nonmotor processing, particularly cognitive and affective modulation, is described, and the theoretical implications of these anatomic findings are discussed.
Abstract: The cerebellum has massive reciprocal interconnections with the cerebral cortex and with cerebral subcortical structures that complement its interconnections with the spinal cord and brainstem. The major cerebrocerebellar link is mediated by the feedforward/afferent corticopontine projections and mossy fibers emanating from the pontocerebellar projections, and the feedback/efferent cerebellothalamic and thalamocortical projections. These highly arranged connections link sensorimotor, associative and limbic regions of cerebral cortex with the cerebellum and the intervening pontine nuclei and thalamus in a topographically precise manner. The cerebellum also has reciprocal links with the basal ganglia and hypothalamus, and with structures in the limbic circuit. In addition to these mossy fiber afferents to cerebellum, the inferior olive receives indirect input from motor and associative regions of the cerebral cortex by way of the red nucleus and zona incerta, and it conveys these inputs to cerebellum via climbing fibers. The cerebrocerebellar pathways are organized into segregated loops of information processing and stand in contrast to the cerebellar cortical architecture that is essentially uniform. Knowledge of cerebrocerebellar circuits is critical to understanding theories of the cerebellar contribution to motor and nonmotor function, and to the diagnosis and management of patients with lesions in these pathways.
TL;DR: It is shown that Hcy treatment of bovine aortic endothelial cells leads to a dose-dependent decrease in NO x independent of endothelial nitric-oxide synthase activity or protein levels and nos3 transcription, suggesting that HCy affects the bioavailability of NO, not its production.
TL;DR: In this article, a thin slab of two-dimensional photonic crystal is shown to alter drastically the radiation pattern of spontaneous emission, and spontaneous emission can be coupled entirely to free space modes, resulting in a greatly enhanced extraction efficiency.
Abstract: A thin slab of two-dimensional photonic crystal is shown to alter drastically the radiation pattern of spontaneous emission. More specifically, by eliminating all guided modes at the transition frequencies, spontaneous emission can be coupled entirely to free space modes, resulting in a greatly enhanced extraction efficiency. Such structures might provide a solution to the long-standing problem of poor light extraction from high refractive-index semiconductors in light-emitting diodes.
TL;DR: In this paper, stable isotope data from a series of estuaries receiving nitrogen loads from 2 to 467 kg N ha -1 yr -1 from the Waquoit Bay watershed, Cape Cod, Massachusetts, indicate that producer and consumer 15 N to 14 N ratios record increases in wastewater nitrogen inputs.
Abstract: Nutrient enrichment as a result of anthropogenic activity concentrated along the land-sea margin is increasing eutrophication of near-shore waters across the globe. Management of eutrophication in the coastal zone has been hampered by the lack of a direct method to trace nitrogen sources from land into coastal food webs. Stable isotope data from a series of estuaries receiving nitrogen loads from 2 to 467 kg N ha -1 yr -1 from the Waquoit Bay watershed, Cape Cod, Massachusetts, indicate that producer and consumer 15 N-to- 14 N ratios record increases in wastewater nitrogen inputs. Nitrate from groundwater-borne wastewater introduces a 15 N-enriched tracer to estuaries. This study explicitly links anthropogenically derived nitrogen from watersheds to nitrogen in estuarine plants and animals, and suggests that wastewater nitrogen may be detectable in estuarine biota at relatively low loading rates, before eutrophication leads to major changes in species composition and abundance within estuarine food webs.
TL;DR: In this paper, biochemical measurements showed increased concentrations of 3-nitrotyrosine and 3nitro-4-hydroxyphenylacetic acid in the lumbar and thoracic spinal cord of ALS patients, indicating that peroxynitrite mediated oxidative damage may play a role in the pathogenesis of both sporadic and familial ALS.
Abstract: The pathogenesis of neuronal degeneration in both sporadic and familial amyotrophic lateral sclerosis (ALS) associated with mutations in superoxide dismutase may involve oxidative stress. A leading candidate as a mediator of oxidative stress is peroxynitrite, which is formed by the reaction of superoxide with nitric oxide. 3-Nitrotyrosine is a relatively specific marker for oxidative damage mediated by peroxynitrite. In the present study, biochemical measurements showed increased concentrations of 3-nitrotyrosine and 3-nitro-4-hydroxyphenylacetic acid in the lumbar and thoracic spinal cord of ALS patients. Increased 3-nitrotyrosine immunoreactivity was observed in motor neurons of both sporadic and familial ALS patients. Neurologic control patients with cerebral ischemia also showed increased 3-nitrotyrosine immunoreactivity. These findings suggest that peroxynitrite-mediated oxidative damage may play a role in the pathogenesis of both sporadic and familial ALS.
TL;DR: The results imply that striatal damage in Huntington's disease is almost entirely a lineaar function of the length of the polyglutamine stretch beyond 35.5 repeats, and it is predicted that the pathological process develops linearly from birth.
Abstract: We compared the number of CAG repeats, the age at death, and the severity of neuropathology in 89 Huntington's disease brains. We found a linear correlation between the CAG repeat number and the quotient of the degree of atrophy in the striatum (the brain region most severely affected in Huntington's disease) divided by age at death, with an intercept at 35.5 repeats. The largest CAG repeat length, therefore, at which no pathology is expected to develop is 35.5. These results imply that striatal damage in Huntington's disease is almost entirely a lineaar function of the length of the polyglutamine stretch beyond 35.5 glutamines multiplied by the age of the patient. Thus, it is predicted that the pathological process develops linearly from birth. Analysis of other measures of striatal function could test this hypothesis and might determine when treatment for CAG repeat diseases should start.
TL;DR: Zinbarg et al. as mentioned in this paper proposed a hierarchical factor model for the ASI and found that the higher order, general factor accounts for 60% of the variance in ASI total scores.
Abstract: Boston University The Anxiety Sensitivity Index (ASI) is one of the most widely used measures of the construct of anxiety sensitivity. Until the recent introduction of a hierarchical model of the ASI by S. Lilienfeld, Turner, and Jacob (1993), the factor structure of the ASI was the subject of debate, with some researchers advocating a unidimensional structure and others proposing multidimensional structures. In the present study, involving 432 outpatients seeking treatment at an anxiety disorders clinic and 32 participants with no mental disorder, the authors tested a hierarchical factor model. The results supported a hierarchical factor structure consisting of 3 lower order factors and 1 higher order factor. It is estimated that the higher order, general factor accounts for 60% of the variance in ASI total scores. The implications of these findings for the conceptualization and assessment of anxiety sensitivity are discussed. Reiss and his colleagues (Reiss, 1987; Reiss & McNally, 1985; Reiss, Peterson, Gursky, & McNally, 1986) have defined the construct of anxiety sensitivity (AS) as fear of anxiety and physical sensations related to anxiety, and they hypothesize that this fear arises from beliefs that anxiety and related physical sensations have harmful somatic, psychological, or social conse- quences. AS and closely related constructs have played a central role in recent theorizing about the nature and etiology of the anxiety disorders in general and panic disorder in particular (e.g., Barlow, 1988, 1991; Clark, 1986; Goldstein & Chambless, 1978; McNally, 1990; Reiss, 1991; Reiss & McNally, 1985; Reiss et al., 1986). Reiss et al. (1986) created one of the most Richard E. Zinbarg, Department of Psychology, University of Oregon; David H. Barlow and Timothy A. Brown, Center for Anxiety and Related Disorders, Boston University. This work was supported in part by Grant RO1M-39096 from the National Institute of Mental Health and by a Shannon Award (1 R55 MH/OD53425-01A1 ) from the National Institute of Mental Health. We are grateful to the individuals who graciously consented to serve as judges for the matching task. The judges included seven PhD-level psy- chologists with expertise in clinical psychology (Anne Marie Albano, Janet Borden, Paul Collins, Peter M. Lewinsohn, Susan Mineka, Anne Simons, and Robert Weiss), two PhD-level psychologists with expertise in personality and factor analysis (Lewis R. Goldberg, William R. Re- velle), and three graduate students in clinical psychology who had just completed an anxiety assessment and treatment practicum with Richard E. Zinbarg (Leslie Dana, Amy Reiss, Carie Rodgers). We thank Stephen Haynes, Scott O. Lilienfeld, Janet Mohlman, and Steven Taylor for their extensive and helpful comments on earlier versions of this article. We also thank Brian Cox, Steven Taylor, and Sherry Stewart for graciously providing the factor loadings from their analyses that have not yet been published. We are also grateful to Steven Taylor for providing the factor loadings from Peterson and Heilbronner's (1987) four-factor solution because these results are unpublished. Correspondence concerning this article should be addressed to Rich- ard E. Zinbarg, Department of Psychology, 1227 University of Oregon, Eugene, Oregon 97403-1227. Electronic mall may be sent via the In- ternet to rzin@oregon.uoregon.edu. 277 widely used measures of the AS construct, known as the Anxiety Sensitivity Index (ASI). Until recently, there has been considerable debate surrounding the issue of the factor structure of the ASI. On the one hand, Reiss et al. (1986) and several other researchers (e.g., Pe- terson & Heilbronner, 1987; Reiss, Peterson, & Gursky, 1988; Sandin, Chorot, & McNally, 1996; Stewart, Dubois-Nguyen, & Pihl, 1990; Taylor, Koch, & Crockett, 1991; Taylor, Koch, McNally, & Crockett, 1992) advocated a unidimensional struc- ture, whereas others (e.g,, Telch, Shermis, & Lewis, 1989; War- die, Ahmad, & Hayward, 1990) advocated a multidimensional structure including as many as four factors. The debate regarding the factor structure of the ASI appears to have been largely resolved by a hierarchical model proposed by Lilienfeld, Turner, and Jacob (1993). Their model is hierar- chical in that it contains several first-order factors that aU load on a single, higher order factor. Furthermore, it is capable of integrating many of the apparently discrepant findings in the literature by suggesting that those investigators who have advo- cated a multifactor solution were focused on the lower level of the hierarchy, whereas those who have advocated a single-factor solution were focused on the higher level. Indeed, the hierarchi- cal model appears to have been largely accepted by Taylor (1995a), who was formerly one of the main proponents of the unifactorial view. Given the relatively long history of hierarchi- cal models of intelligence, an analogy to the structure of intelli- gence may be useful. Within a hierarchical model of intelligence, the identification of separable lower order factors would not dispute the existence of a general intelligence factor. Fur exam- ple, at least two group factors (e.g., Verbal and Spatial) in addition to a general factor of intelligence are hypothesized in Vernon's (1969) model of intelligence. Similarly, Lilienfeld et al. suggested that there may be group factors (i.e., common to some but not all items) and a general factor (i.e., common to nearly all items) underlying the ASI. Although a hierarchical model has promise for resolving con- troversies in this area, appropriate tests of the hierarchical nature