Showing papers by "State University of New York System published in 2003"

Biogeochemical Hot Spots and Hot Moments at the Interface of Terrestrial and Aquatic Ecosystems

Abstract: Rates and reactions of biogeochemical processes vary in space and time to produce both hot spots and hot moments of elemental cycling. We define biogeochemical hot spots as patches that show disproportionately high reaction rates relative to the surrounding matrix, whereas hot moments are defined as short periods of time that exhibit disproportionately high reaction rates relative to longer intervening time periods. As has been appreciated by ecologists for decades, hot spot and hot moment activity is often enhanced at terrestrial-aquatic interfaces. Using examples from the carbon (C) and nitrogen (N) cycles, we show that hot spots occur where hydrological flowpaths converge with substrates or other flowpaths containing complementary or missing reactants. Hot moments occur when episodic hydrological flowpaths reactivate and/or mobilize accumulated reactants. By focusing on the delivery of specific missing reactants via hydrologic flowpaths, we can forge a better mechanistic understanding of the factors that create hot spots and hot moments. Such a mechanistic understanding is necessary so that biogeochemical hot spots can be identified at broader spatiotemporal scales and factored into quantitative models. We specifically recommend that resource managers incorporate both natural and artificially created biogeochemical hot spots into their plans for water quality management. Finally, we emphasize the needs for further research to assess the potential importance of hot spot and hot moment phenomena in the cycling of different bioactive elements, improve our ability to predict their occurrence, assess their importance in landscape biogeochemistry, and evaluate their utility as tools for resource management.

Estimating the Relative Risk in Cohort Studies and Clinical Trials of Common Outcomes

Abstract: Logistic regression yields an adjusted odds ratio that approximates the adjusted relative risk when disease incidence is rare (<10%), while adjusting for potential confounders. For more common outcomes, the odds ratio always overstates the relative risk, sometimes dramatically. The purpose of this paper is to discuss the incorrect application of a proposed method to estimate an adjusted relative risk from an adjusted odds ratio, which has quickly gained popularity in medical and public health research, and to describe alternative statistical methods for estimating an adjusted relative risk when the outcome is common. Hypothetical data are used to illustrate statistical methods with readily accessible computer software.

Unscented Filtering for Spacecraft Attitude Estimation

Abstract: A new spacecraft attitude estimation approach based on the unscented filter is derived. For nonlinear systems the unscented filter uses a carefully selected set of sample points to map the probability distribution more accurately than the linearization of the standard extended Kalman filter, leading to faster convergence from inaccurate initial conditions in attitude estimation problems. The filter formulation is based on standard attitude-vector measurements using a gyro-based model for attitude propagation. The global attitude parameterization is given by a quaternion, whereas a generalized three-dimensional attitude representation is used to define the local attitude error. A multiplicative quaternion-error approach is derived from the local attitude error, which guarantees that quaternion normalization is maintained in the filter. Simulation results indicate that the unscented filter is more robust than the extended Kalman filter under realistic initial attitude-error conditions.

Ceramic-Based Nanoparticles Entrapping Water-Insoluble Photosensitizing Anticancer Drugs: A Novel Drug−Carrier System for Photodynamic Therapy

Abstract: A novel nanoparticle-based drug carrier for photodynamic therapy is reported which can provide stable aqueous dispersion of hydrophobic photosensitizers, yet preserve the key step of photogeneration of singlet oxygen, necessary for photodynamic action. A multidisciplinary approach is utilized which involves (i) nanochemistry in micellar cavity to produce these carriers, (ii) spectroscopy to confirm singlet oxygen production, and (iii) in vitro studies using tumor cells to investigate drug-carrier uptake and destruction of cancer cells by photodynamic action. Ultrafine organically modified silica-based nanoparticles (diameter approximately 30 nm), entrapping water-insoluble photosensitizing anticancer drug 2-devinyl-2-(1-hexyloxyethyl) pyropheophorbide, have been synthesized in the nonpolar core of micelles by hydrolysis of triethoxyvinylsilane. The resulting drug-doped nanoparticles are spherical, highly monodispersed, and stable in aqueous system. The entrapped drug is more fluorescent in aqueous medium than the free drug, permitting use of fluorescence bioimaging studies. Irradiation of the photosensitizing drug entrapped in nanoparticles with light of suitable wavelength results in efficient generation of singlet oxygen, which is made possible by the inherent porosity of the nanoparticles. In vitro studies have demonstrated the active uptake of drug-doped nanoparticles into the cytosol of tumor cells. Significant damage to such impregnated tumor cells was observed upon irradiation with light of wavelength 650 nm. Thus, the potential of using ceramic-based nanoparticles as drug carriers for photodynamic therapy has been demonstrated.

The Influence of Social Support on Chronic Illness Self-Management: A Review and Directions for Research

Abstract: A review of the empirical literature examining the relationship between social support and chronic illness self-management identified 29 articles, of which 22 were quantitative and 7 were qualitative. The majority of research in this area concerns diabetes self-management, with a few studies examining asthma, heart disease, and epilepsy management. Taken together, these studies provide evidence for a modest positive relationship between social support and chronic illness self-management, especially for diabetes. Dietary behavior appears to be particularly susceptible to social influences. In addition, social network members have potentially important negative influences on self-management There is a need to elucidate the underlying mechanisms by which support influences self-management and to examine whether this relationship varies by illness, type of support, and behavior. There is also a need to understand how the social environment may influence self-management in ways other than the provision of social support

Religiosity and Mental Health: A Meta–Analysis of Recent Studies

Abstract: A meta–analysis was performed in an attempt to clarify the proposed relationship between religiosity and psychological adjustment. Specific focus was given to the issue of definition, namely, whether differences in researchers’ conceptualizations of religiosity and mental health could account for the various contradictory findings by psychologists of religion. Analysis of 34 studies conducted during the past 12 years revealed that the definitions of religiosity and mental health utilized by psychologists in this field were indeed associated with different types and strengths of the correlations between religiosity and mental health. Discussion of results assesses the fit between relevant theory and the pattern of change in effect size across categories of religion and adjustment, and concludes with implications for therapeutic uses of religious involvement.

How Critical are Critical Reviews? The Box Office Effects of Film Critics, Star Power, and Budgets:

Abstract: The authors investigate how critics affect the box office performance of films and how the effects may be moderated by stars and budgets. The authors examine the process through which critics affect box office revenue, that is, whether they influence the decision of the film going public (their role as influencers), merely predict the decision (their role as predictors), or do both. They find that both positive and negative reviews are correlated with weekly box office revenue over an eight-week period, suggesting that critics play a dual role: They can influence and predict box office revenue. However, the authors find the impact of negative reviews (but not positive reviews) to diminish over time, a pattern that is more consistent with critics’ role as influencers. The authors then compare the positive impact of good reviews with the negative impact of bad reviews to find that film reviews evidence a negativity bias; that is, negative reviews hurt performance more than positive reviews help performance, but only during the first week of a film’s run. Finally, the authors examine two key moderators of critical reviews, stars and budgets, and find that popular stars and big budgets enhance box office revenue for films that receive more negative critical reviews than positive critical reviews but do little for films that receive more positive reviews than negative reviews. Taken together, the findings not only replicate and extend prior research on critical reviews and box office performance but also offer insight into how film studios can strategically manage the review process to enhance box office revenue.

Gaussian particle filtering

Abstract: Sequential Bayesian estimation for nonlinear dynamic state-space models involves recursive estimation of filtering and predictive distributions of unobserved time varying signals based on noisy observations. This paper introduces a new filter called the Gaussian particle filter. It is based on the particle filtering concept, and it approximates the posterior distributions by single Gaussians, similar to Gaussian filters like the extended Kalman filter and its variants. It is shown that under the Gaussianity assumption, the Gaussian particle filter is asymptotically optimal in the number of particles and, hence, has much-improved performance and versatility over other Gaussian filters, especially when nontrivial nonlinearities are present. Simulation results are presented to demonstrate the versatility and improved performance of the Gaussian particle filter over conventional Gaussian filters and the lower complexity than known particle filters.

A Mathematical Representation of Near-Fault Ground Motions

Abstract: A simple, yet effective, analytical model is proposed for the representation of near-field strong ground motions. The model adequately describes the impulsive character of near-fault ground motions both qualitatively and quantitatively. In addition, it can be used to analytically reproduce empirical observations that are based on available near-source records. The input parameters of the model have an unambiguous physical meaning. The proposed analytical model has been calibrated using a large number of actual near-field ground-motion records. It successfully simulates the entire set of available near-fault displacement, velocity, and (in many cases) acceleration time histories, as well as the corresponding deformation, velocity, and acceleration response spectra. Furthermore, a very simplified methodology for generating realistic synthetic ground motions that are adequate for engineering analysis and design is outlined and applied. Finally, it should be noted that the analytical model (along with the scaling laws of its parameters) proposed in the present work has the potential to facilitate the study of the elastic and inelastic response of conventional, nonconventional (e.g., base-isolated), and special structures (e.g., suspension bridges, fluid-storage tanks) subjected to near-source seismic excitations as a function of the model input parameters and thus, ultimately, as a function of earthquake size.

Role of Glycosylation in Development

Abstract: Researchers have long predicted that complex carbohydrates on cell surfaces would play important roles in developmental processes because of the observation that specific carbohydrate structures appear in specific spatial and temporal patterns throughout development. The astounding number and complexity of carbohydrate structures on cell surfaces added support to the concept that glycoconjugates would function in cellular communication during development. Although the structural complexity inherent in glycoconjugates has slowed advances in our understanding of their functions, the complete sequencing of the genomes of organisms classically used in developmental studies (e.g., mice, Drosophila melanogaster, and Caenorhabditis elegans) has led to demonstration of essential functions for a number of glycoconjugates in developmental processes. Here we present a review of recent studies analyzing function of a variety of glycoconjugates (O-fucose, O-mannose, N-glycans, mucin-type O-glycans, proteoglycans, glycosphingolipids), focusing on lessons learned from human disease and genetic studies in mice, D. melanogaster, and C. elegans.

The origin of modern human behavior.

Abstract: Archaeology’s main contribution to the debate over the origins of modern humans has been investigating where and when modern human behavior is first recognized in the archaeological record. Most of this debate has been over the empirical record for the appearance and distribution of a set of traits that have come to be accepted as indicators of behavioral modernity. This debate has resulted in a series of competing models that we explicate here, and the traits are typically used as the test implications for these models. However, adequate tests of hypotheses and models rest on robust test implications, and we argue here that the current set of test implications suffers from three main problems: (1) Many are empirically derived from and context‐specific to the richer European record, rendering them problematic for use in the primarily tropical and subtropical African continent. (2) They are ambiguous because other processes can be invoked, often with greater parsimony, to explain their character. (3) Many ...

Missing Data, Incomplete Taxa, and Phylogenetic Accuracy

Abstract: The problem of missing data is often considered to be the most important obstacle in reconstructing the phylogeny of fossil taxa and in combining data from diverse characters and taxa for phylogenetic analysis. Empirical and theoretical studies show that including highly incomplete taxa can lead to multiple equally parsimonious trees, poorly resolved consensus trees, and decreased phylogenetic accuracy. However, the mechanisms that cause incomplete taxa to be problematic have remained unclear. It has been widely assumed that incomplete taxa are problematic because of the proportion or amount of missing data that they bear. In this study, I use simulations to show that the reduced accuracy associated with including incomplete taxa is caused by these taxa bearing too few complete characters rather than too many missing data cells. This seemingly subtle distinction has a number of important implications. First, the so-called missing data problem for incomplete taxa is, paradoxically, not directly related to their amount or proportion of missing data. Thus, the level of completeness alone should not guide the exclusion of taxa (contrary to common practice), and these results may explain why empirical studies have sometimes found little relationship between the completeness of a taxon and its impact on an analysis. These results also (1) suggest a more effective strategy for dealing with incomplete taxa, (2) call into question a justification of the controversial phylogenetic supertree approach, and (3) show the potential for the accurate phylogenetic placement of highly incomplete taxa, both when combining diverse data sets and when analyzing relationships of fossil taxa.

Elevation of free fatty acids induces inflammation and impairs vascular reactivity in healthy subjects.

Abstract: To test the possible acute proinflammatory effects of fatty acids, we induced an increase in plasma free fatty acid (FFA) concentrations after a lipid and heparin infusion for 4 h in 10 healthy subjects. We determined the nuclear factor-kappaB (NF-kappaB) binding activity in mononuclear cells (MNCs), the p65 subunit of NF-kappaB, reactive oxygen species (ROS) generation by MNC, and polymorphonuclear leukocytes (PMN). Brachial artery reactivity, using postischemic flow-mediated dilation, was also measured. NF-kappaB binding activity in the MNC nuclear extracts increased to 163 +/- 17% and 144 +/- 14% as compared with basal levels at 2 and 4 h (P < 0.005) and remained elevated (P < 0.05) at 6 h (2 h after cessation of lipid infusion). NF-kappaB p65 subunit protein expression in MNC homogenates also increased at 2, 4, and 6 h (P < 0.05). ROS generation by PMNs increased significantly at 2 and 4 h (P < 0.005), whereas that by MNCs increased at 4 h (P < 0.05). Plasma macrophage migration inhibitory factor increased at 2 (P < 0.05) and 4 h (P < 0.005), respectively, and declined to baseline at 6 h. The postischemic flow-mediated dilation of brachial artery decreased from 6.3 +/- 1.1% at baseline to 4.3 +/- 1.9% and 2.7 +/- 2.1% (P < 0.01) at 2, 4, and 6 h, respectively. We conclude that an increase in FFA concentration induces oxidative stress and has a proinflammatory effect; it also impairs postischemic flow-mediated vasodilation of the brachial artery.

Response of a deciduous forest to the Mount Pinatubo eruption: enhanced photosynthesis.

Abstract: Volcanic aerosols from the 1991 Mount Pinatubo eruption greatly increased diffuse radiation worldwide for the following 2 years. We estimated that this increase in diffuse radiation alone enhanced noontime photosynthesis of a deciduous forest by 23% in 1992 and 8% in 1993 under cloudless conditions. This finding indicates that the aerosol-induced increase in diffuse radiation by the volcano enhanced the terrestrial carbon sink and contributed to the temporary decline in the growth rate of atmospheric carbon dioxide after the eruption.

An integrated global model of present-day plate motions and plate boundary deformation

Abstract: SUMMARY In this paper we present a global model (GSRM-1) of both horizontal velocities on the Earth’s surface and horizontal strain rates for almost all deforming plate boundary zones. A model strain rate field is obtained jointly with a global velocity field in the process of solving for a global velocity gradient tensor field. In our model we perform a least-squares fit between model velocities and observed geodetic velocities, as well as between model strain rates and observed geological strain rates. Model velocities and strain rates are interpolated over a spherical Earth using bi-cubic Bessel splines. We include 3000 geodetic velocities from 50 different, mostly published, studies. Geological strain rates are obtained for central Asia only and they are inferred from Quaternary fault slip rates. For all areas where no geological information is included a priori constraints are placed on the style and direction (but not magnitude) of the model strain rate field. These constraints are taken from a seismic strain rate field inferred from (normalized) focal mechanisms of shallow earthquakes. We present a global solution of the second invariant of the model strain rate field as well as strain rate solutions for a few selected plate boundary zones. Generally, the strain rate tensor field is consistent with geological and seismological data. With the assumption of plate rigidity for all areas other than the plate boundary zones we also present relative angular velocities for most plate pairs. We find that in general there is a good agreement between the present-day plate motions we obtain and longterm plate motions, but a few significant differences exist. The rotation rates for the Indian, Arabian and Nubian plates relative to Eurasia are 30, 13 and 50 per cent slower than the NUVEL1A estimate, respectively, and the rotation rate for the Nazca Plate relative to South America is 17 per cent slower. On the other hand, Caribbean‐North America motion is 76 per cent faster than the NUVEL-1A estimate. While crustal blocks in the India‐Eurasia collision zone move significantly and self-consistently with respect to bounding plates, only a very small motion is predicted between the Nubian and Somalian plates. By integrating plate boundary zone deformation with the traditional modelling of angular velocities of rigid plates we have obtained a model that has already been proven valuable in, for instance, redefining a no-net-rotation model of surface motions and by confirming a global correlation between seismicity rates and tectonic moment rates along subduction zones and within zones of continental deformation.

Prevention of postmenopausal bone loss by a low-magnitude, high-frequency mechanical stimuli: a clinical trial assessing compliance, efficacy, and safety.

Abstract: A 1-year prospective, randomized, double-blind, and placebo-controlled trial of 70 postmenopausal women demonstrated that brief periods (<20 minutes) of a low-level (0.2g, 30 Hz) vibration applied during quiet standing can effectively inhibit bone loss in the spine and femur, with efficacy increasing significantly with greater compliance, particularly in those subjects with lower body mass. Introduction: Indicative of the anabolic potential of mechanical stimuli, animal models have demonstrated that short periods (<30 minutes) of low-magnitude vibration (<0.3g), applied at a relatively high frequency (20–90 Hz), will increase the number and width of trabeculae, as well as enhance stiffness and strength of cancellous bone. Here, a 1-year prospective, randomized, double-blind, and placebo-controlled clinical trial in 70 women, 3–8 years past the menopause, examined the ability of such high-frequency, low-magnitude mechanical signals to inhibit bone loss in the human. Materials and Methods: Each day, one-half of the subjects were exposed to short-duration (two 10-minute treatments/day), low-magnitude (2.0 m/s2 peak to peak), 30-Hz vertical accelerations (vibration), whereas the other half stood for the same duration on placebo devices. DXA was used to measure BMD at the spine, hip, and distal radius at baseline, and 3, 6, and 12 months. Fifty-six women completed the 1-year treatment. Results and Conclusions: The detection threshold of the study design failed to show any changes in bone density using an intention-to-treat analysis for either the placebo or treatment group. Regression analysis on the a priori study group demonstrated a significant effect of compliance on efficacy of the intervention, particularly at the lumbar spine (p = 0.004). Posthoc testing was used to assist in identifying various subgroups that may have benefited from this treatment modality. Evaluating those in the highest quartile of compliance (86% compliant), placebo subjects lost 2.13% in the femoral neck over 1 year, whereas treatment was associated with a gain of 0.04%, reflecting a 2.17% relative benefit of treatment (p = 0.06). In the spine, the 1.6% decrease observed over 1 year in the placebo group was reduced to a 0.10% loss in the active group, indicating a 1.5% relative benefit of treatment (p = 0.09). Considering the interdependence of weight, the spine of lighter women (<65 kg), who were in the highest quartile of compliance, exhibited a relative benefit of active treatment of 3.35% greater BMD over 1 year (p = 0.009); for the mean compliance group, a 2.73% relative benefit in BMD was found (p = 0.02). These preliminary results indicate the potential for a noninvasive, mechanically mediated intervention for osteoporosis. This non-pharmacologic approach represents a physiologically based means of inhibiting the decline in BMD that follows menopause, perhaps most effectively in the spine of lighter women who are in the greatest need of intervention.

The effects of physical attractiveness on job‐related outcomes: a meta‐analysis of experimental studies

Abstract: We report the findings of a meta-analytic review of experimental studies concerned with the biasing effect of physical attractiveness on a variety of job-related outcomes. In support of implicit personality theory, attractive individuals were found to fare better than unattractive individuals in terms of a number of such outcomes. The weighted mean effect size, d, was .37 for all studies. In addition, tests for moderating effects showed that (a) the attractiveness bias did not differ between studies that provided low versus high amounts of job-relevant information about the targets, (b) the same bias was greater for within-subjects research designs than for between-subjects designs, (c) professionals were as susceptible to the bias as were college students, (d) attractiveness was as important for men as for women, and (e) the biasing effect of attractiveness has decreased in recent years. Implications of these findings are considered.

Associations between periodontal disease and risk for atherosclerosis, cardiovascular disease, and stroke. A systematic review.

Abstract: Background: Recent studies implicate exposure to systemic conditions involving chronic inflammation, including chronic periodontitis, in the etiology of atherosclerosis Rationale: A systematic review of the literature was conducted to assess the association between chronic inflammatory periodontal disease and atherosclerosis. Focused Question:Does periodontal disease influence the initiation/ progression of atherosclerosis and, therefore, cardiovascular disease (CVD), stroke, and peripheral vascular disease (PVD)? Search Protocol: MEDLINE, pre-MEDLINE, MEDLINE Daily Update, and the Cochrane Controlled Trials Register were searched to identify human studies that related variables associated with atherosclerosis to periodontal disease. Searches were made for papers published from 1966 through March 2002. Inclusion criteria: Published randomized controlled clinical trials (RCTs), longitudinal, cohort, and case-control studies were included. Study participants included those with atherosclerosis, myocardial i...

Gaussian sum particle filtering

Abstract: We use the Gaussian particle filter to build several types of Gaussian sum particle filters. These filters approximate the filtering and predictive distributions by weighted Gaussian mixtures and are basically banks of Gaussian particle filters. Then, we extend the use of Gaussian particle filters and Gaussian sum particle filters to dynamic state space (DSS) models with non-Gaussian noise. With non-Gaussian noise approximated by Gaussian mixtures, the non-Gaussian noise models are approximated by banks of Gaussian noise models, and Gaussian mixture filters are developed using algorithms developed for Gaussian noise DSS models. As a result, problems involving heavy-tailed densities can be conveniently addressed. Simulations are presented to exhibit the application of the framework developed herein, and the performance of the algorithms is examined.

The extratropical transition of tropical cyclones : forecast challenges, current understanding, and future directions

Abstract: A significant number of tropical cyclones move into the midlatitudes and transform into extratropical cyclones. This process is generally referred to as extratropical transition (ET). During ET a cyclone frequently produces intense rainfall and strong winds and has increased forward motion, so that such systems pose a serious threat to land and maritime activities. Changes in the structure of a system as it evolves from a tropical to an extratropical cyclone during ET necessitate changes in forecast strategies. In this paper a brief climatology of ET is given and the challenges associated with forecasting extratropical transition are described in terms of the forecast variables (track, intensity, surface winds, precipitation) and their impacts (flooding, bush fires, ocean response). The problems associated with the numerical prediction of ET are discussed. A comprehensive review of the current understanding of the processes involved in ET is presented. Classifications of extratropical transition ...

Associations Between Periodontal Disease and Risk for Nosocomial Bacterial Pneumonia and Chronic Obstructive Pulmonary Disease. A Systematic Review

Abstract: Background: Several recent studies provide evidence that the oral cavity may influence the initiation and/or the progression of lung diseases such as pneumonia and chronic obstructive pulmonary disease (COPD). Rationale: Studies have shown that poor oral hygiene and periodontal disease may foster colonization of the oropharyngeal region by respiratory pathogens, particularly in hospital or nursing home patients. If aspirated, these pathogens can cause pneumonia, one of the most common respiratory infections, especially in institutionalized subjects. Other cross-sectional epidemiologic studies point to an association between periodontal disease and COPD. This systematic review examines the literature to determine if interventions that improve oral hygiene reduce the rate of pneumonia in high-risk populations. Focused Question: Do periodontal diseases or other indicators of poor oral health influence the initiation/ progression of pneumonia or other lung diseases? Search Protocol: MEDLINE, pre-MEDLINE, MEDL...

Alcohol as a Risk Factor for Global Burden of Disease

Abstract: Aim: To make quantitative estimates of the burden of disease attributable to alcohol in the year 2000 on a global basis. Design: Secondary data analysis.

Collecting and analyzing qualitative data for system dynamics: methods and models

Abstract: System dynamics depends heavily upon quantitative data to generate feedback models. Qualitative data and their analysis also have a central role to play at all levels of the modeling process. Although the classic literature on system dynamics strongly supports this argument, the protocols to incorporate this information during the modeling process are not detailed by the most influential authors. Data-gathering techniques such as interviews and focus groups, and qualitative data analysis techniques such as grounded theory methodology and ethnographic decision models could have a strong, critical role in rigorous system dynamics efforts. This article describes some of the main qualitative, social science techniques and explores their suitability in the different stages of the modeling process. Additionally, the authors argue that the techniques described in the paper could contribute to the understanding of the modeling process, facilitate communication among modelers and clients, and set up a methodological framework to promote constructive discussion around the merits of qualitative versus quantitative modeling. Copyright © 2003 John Wiley & Sons, Ltd.

Fatigue associated with multiple sclerosis: diagnosis, impact and management.

Abstract: In patients with multiple sclerosis (MS) fatigue is the most common symptom and one of the most disabling features. As many as 40% have described it as the single most disabling symptom--a higher percentage than weakness, spasticity, motor problems, or bowel or bladder problems. The etiology and pathophysiology of MS-related fatigue remain unknown. Studies have failed to demonstrate an association between MS-related fatigue and the level of disability, clinical disease subtype, or gender, although recent data show an association between MS-related fatigue and depression and quality of life. Imaging studies using positron emission tomography suggest that fatigue in MS is related to hypometabolism of specific brain areas, including the frontal and subcortical circuits. The impact of fatigue on patient functioning and quality of life clearly warrants intervention. In addition to nonpharmacologic measures, such as exercise and energy conservation strategies, several pharmacologic agents have been evaluated for their ability to reduce MS-related fatigue, including amantadine, central nervous system stimulants (pemoline), and the novel wake-promoting agent modafinil.

The Mus81/Mms4 endonuclease acts independently of double-Holliday junction resolution to promote a distinct subset of crossovers during meiosis in budding yeast.

Abstract: Current models for meiotic recombination require that crossovers derive from the resolution of a double-Holliday junction (dHJ) intermediate In prokaryotes, enzymes responsible for HJ resolution are well characterized but the identification of a eukaryotic nuclear HJ resolvase has been elusive Indirect evidence suggests that MUS81 from humans and fission yeast encodes a HJ resolvase We provide three lines of evidence that Mus81/Mms4 is not the major meiotic HJ resolvase in S cerevisiae: (1) MUS81/MMS4 is required to form only a distinct subset of crossovers; (2) rather than accumulating, dHJ intermediates are reduced in an mms4 mutant; and (3) expression of a bacterial HJ resolvase has no suppressive effect on mus81 meiotic phenotypes Our analysis also reveals the existence of two distinct classes of crossovers in budding yeast Class I is dependent upon MSH4/MSH5 and exhibits crossover interference, while class II is dependent upon MUS81/MMS4 and exhibits no interference mms4 specifically reduces crossing over on small chromosomes, which are known to undergo less interference The correlation between recombination rate and degree of interference to chromosome size may therefore be achieved by modulating the balance between class I/class II crossovers

Subordinants of differential superordinations

Abstract: Let Ω be any set in the complex plane ℂ, let p be analytic in the unit disk U and let ψ (r, s, t; z). In this article we consider the problem of determining properties of functions p that satisfy the differential superordination Ω ⊂ {ψ(p(z), z 2 p"(z);z)|z ∈ U}.