345 research outputs found
The Fission Yeast S-Phase Cyclin Cig2 Can Drive Mitosis [preprint]
Commitment to mitosis is regulated by cyclin-dependent kinase (CDK) activity. In the fission yeast Schizosaccharomyces pombe, the major B-type cyclin, Cdc13, is necessary and sufficient to drive mitotic entry. Furthermore, Cdc13 is also sufficient to drive S phase, demonstrating that a single cyclin can regulate alternating rounds of replication and mitosis and providing the foundation of the quantitative model of CDK function. It has been assumed that Cig2, a B-type cyclin expressed only during S-phase and incapable of driving mitosis in wild-type cells, was specialized for S-phase regulation. Here, we show that Cig2 is capable of driving mitosis. Cig2/CDK activity drives mitotic catastrophe -- lethal mitosis in inviably small cells -- in cells that lack CDK inhibition by tyrosine-phosphorylation. Moreover, Cig2/CDK can drive mitosis in the absence of Cdc13/CDK activity. These results demonstrate that in fission yeast, not only can the presumptive M-phase cyclin drive S phase, but the presumptive S-phase cyclin can drive M phase, further supporting the quantitative model of CDK function. Furthermore, these results provide an explanation, previously proposed on the basis of computation analyses, for the surprising observation that cells expressing a single-chain Cdc13-Cdc2 CDK do not require Y15 phosphorylation for viability. Their viability is due to the fact that in such cells, which lack Cig2/CDK complexes, Cdc13/CDK activity is unable to drive mitotic catastrophe
Adsorption of malachite green and alizarin red s dyes using fe-btc metal organic framework as adsorbent
Synthetic organic dyes are widely used in various industrial sectors but are also among the most harmful water pollutants. In the last decade, significant efforts have been made to develop improved materials for the removal of dyes from water, in particular, on nanostructured adsorbent materials. Metal organic frameworks (MOFs) are an attractive class of hybrid nanostructured materials with an extremely wide range of applications including adsorption. In the present work, an iron-based Fe-BTC MOF, prepared according to a rapid, aqueous-based procedure, was used as an adsorbent for the removal of alizarin red S (ARS) and malachite green (MG) dyes from water. The synthesized material was characterized in detail, while the adsorption of the dyes was monitored by UV-Vis spectroscopy. An optimal adsorption pH of 4, likely due to the establishment of favor-able interactions between dyes and Fe-BTC, was found. At this pH and at a temperature of 298 K, adsorption equilibrium was reached in less than 30 min following a pseudo-second order kinetics, with kâ of 4.29 Ă 10â3 and 3.98 Ă 10â2 gâmgâ1 minâ1 for ARS and MG, respectively. The adsorption isotherm followed the Langmuir model with maximal adsorption capacities of 80 mgâgâ1 (ARS) and 177 mgâgâ1 (MG), and KL of 9.30â103 Lâmgâ1 (ARS) and 51.56â103 Lâmgâ1 (MG)
Chaoticity and Shell Effects in the Nearest-Neighbor Distributions
Statistics of the single-particle levels in a deformed Woods-Saxon potential
is analyzed in terms of the Poisson and Wigner nearest-neighbor distributions
for several deformations and multipolarities of its surface distortions. We
found the significant differences of all the distributions with a fixed value
of the angular momentum projection of the particle, more closely to the Wigner
distribution, in contrast to the full spectra with Poisson-like behavior.
Important shell effects are observed in the nearest neighbor spacing
distributions, the larger the smaller deformations of the surface
multipolarities.Comment: 10 pages and 9 figure
The Impact of Worksite Weight-Related Social Norms on Associated Behaviors
Objective: To assess the association between descriptive social norms for weight and weight-related behaviors and associated behaviors at the worksite.
Design and Sample: Baseline data from site-randomized trial of a worksite ecological intervention for weight control; 12 public high schools in central Massachusetts; Sample of 844 employees enrolled (~ 2/3 of all employees).
Conclusions: Associations of weight loss and eating social norms with behavior; Unique from social support; No association of physical activity social norms with physical activity; May be little opportunity for and therefore little exposure to physical activity during the workday; Results support the development of weight loss interventions that address social norms for weight loss and eating behaviors at work
Drinking to Cope is Uniquely Associated with Less Specific and Bleaker Future Goal Generation in Young Hazardous Drinkers
This is the final version. Available on open access from Springer via the DOI in this recordGroups with mental health and/or substance use problems generate less detailed descriptions of their future goals. As substance use to cope with negative affect is common to both groups, this characteristic might be uniquely associated with less specific goal descriptions. To test this prediction, 229 past year hazardous drinking undergraduates aged 18â25 years wrote about three positive future life goals in an open-ended survey, before reporting their internalizing (anxiety and depression) symptoms, alcohol dependence severity and motivations for drinking: coping, conformity, enhancement and social. Future goal descriptions were experimenter-rated for detail specificity, and participant-self-rated for positivity, vividness, achievability, and importance. Effort in goal writing was indexed by time spent writing and total word count. Multiple regression analyses revealed that drinking to cope was uniquely associated with the production of less detailed goals, and lower self-rated positivity and vividness of goals (achievability and importance were also marginally lower), over and above internalizing symptoms, alcohol dependence severity, drinking for conformity, enhancement and social motives, age, and gender. However, drinking to cope was not uniquely associated with reduced effort in writing goals: time spent and word count. In sum, drinking to cope with negative affect is a unique characteristic predicting the generation of less detailed and bleaker (less positive and vivid) future goals, and this is not due to lower effort in reporting. Future goal generation may play a role in the aetiology of comorbidity of mental health and substance use problems, and therapeutic targeting of goal generation might benefit both conditions.Alcohol Change UKMedical Research Council (MRC
Analytical perturbative approach to periodic orbits in the homogeneous quartic oscillator potential
We present an analytical calculation of periodic orbits in the homogeneous
quartic oscillator potential. Exploiting the properties of the periodic
Lam{\'e} functions that describe the orbits bifurcated from the fundamental
linear orbit in the vicinity of the bifurcation points, we use perturbation
theory to obtain their evolution away from the bifurcation points. As an
application, we derive an analytical semiclassical trace formula for the
density of states in the separable case, using a uniform approximation for the
pitchfork bifurcations occurring there, which allows for full semiclassical
quantization. For the non-integrable situations, we show that the uniform
contribution of the bifurcating period-one orbits to the coarse-grained density
of states competes with that of the shortest isolated orbits, but decreases
with increasing chaoticity parameter .Comment: 15 pages, LaTeX, 7 figures; revised and extended version, to appear
in J. Phys. A final version 3; error in eq. (33) corrected and note added in
prin
Analytic approach to bifurcation cascades in a class of generalized H\'enon-Heiles potentials
We derive stability traces of bifurcating orbits in H\'enon-Heiles potentials
near their saddlesComment: LaTeX revtex4, 38 pages, 7 PostScript figures, 2 table
Community Perspectives on the Impact of Climate Change on Health in Nunavut, Canada
The purpose of this study was to explore community perspectives on the most important ways that climate change is affecting the health of northern peoples. The study was conducted in Iqaluit, Nunavut, using a participatory action approach and the photovoice research method. Participants identified themes and patterns in the data and developed a visual model of the relationships between the themes identified. Five themes emerged from the data: the direct impacts of climate change on the health of individuals and communities, the transition from past climates to future climates, necessary adaptation to the changing climate in the North, the call to action (individual, regional, and national), and reflection on the past and changing knowledge systems. A climate change and health model was developed to illustrate the relationships between the themes. Participants in this study conceptualized health and climate change broadly. Participants believed that by engaging in a process of ongoing reflection, and by continually incorporating new knowledge and experiences into traditional knowledge systems, communities may be better able to adapt and cope with the challenges to health posed by climate change.Lâobjectif de cette Ă©tude consistait Ă explorer diverses perspectives communautaires quant aux maniĂšres les plus importantes dont le changement climatique a des incidences sur la santĂ© des gens du Nord. LâĂ©tude a Ă©tĂ© rĂ©alisĂ©e Ă Iqaluit, au Nunavut, au moyen dâune mĂ©thode dâaction et de recherche participative faisant appel Ă la « photovoice ». Les participants ont dĂ©terminĂ© les thĂšmes de mĂȘme que les tendances caractĂ©risant les donnĂ©es, puis ont abouti Ă un modĂšle visuel pour Ă©tablir des relations entre les thĂšmes ainsi dĂ©terminĂ©s. Les donnĂ©es ont donnĂ© lieu Ă la formulation de cinq thĂšmes, soit les incidences directes du changement climatique sur la santĂ© des gens et des collectivitĂ©s; la transition des anciens climats aux nouveaux climats; lâadaptation nĂ©cessaire au climat changeant dans le Nord; un appel Ă lâaction (individuel, rĂ©gional et national); et une rĂ©flexion sur les systĂšmes de savoir du passĂ© qui sont en pleine Ă©volution. Ensuite, un modĂšle de changement climatique et de santĂ© a Ă©tĂ© Ă©laborĂ© dans le but dâillustrer les liens existant entre les divers thĂšmes. Les participants Ă cette Ă©tude ont conceptualisĂ© le changement climatique et ses incidences sur la santĂ© Ă grande Ă©chelle. Ils croyaient quâen sâadonnant Ă un processus de rĂ©flexion continue et quâen intĂ©grant constamment de nouvelles connaissances et expĂ©riences aux systĂšmes de savoir traditionnel, les collectivitĂ©s pourraient ĂȘtre mieux placĂ©es pour sâadapter et relever les dĂ©fis posĂ©s par le changement climatique en matiĂšre de santĂ©
The COBE Diffuse Infrared Background Experiment Search for the Cosmic Infrared Background: I. Limits and Detections
The DIRBE on the COBE spacecraft was designed primarily to conduct systematic
search for an isotropic CIB in ten photometric bands from 1.25 to 240 microns.
The results of that search are presented here. Conservative limits on the CIB
are obtained from the minimum observed brightness in all-sky maps at each
wavelength, with the faintest limits in the DIRBE spectral range being at 3.5
microns (\nu I_\nu < 64 nW/m^2/sr, 95% CL) and at 240 microns (\nu I_\nu < 28
nW/m^2/sr, 95% CL). The bright foregrounds from interplanetary dust scattering
and emission, stars, and interstellar dust emission are the principal
impediments to the DIRBE measurements of the CIB. These foregrounds have been
modeled and removed from the sky maps. Assessment of the random and systematic
uncertainties in the residuals and tests for isotropy show that only the 140
and 240 microns data provide candidate detections of the CIB. The residuals and
their uncertainties provide CIB upper limits more restrictive than the dark sky
limits at wavelengths from 1.25 to 100 microns. No plausible solar system or
Galactic source of the observed 140 and 240 microns residuals can be
identified, leading to the conclusion that the CIB has been detected at levels
of \nu I_\nu = 25+-7 and 14+-3 nW/m^2/sr at 140 and 240 microns respectively.
The integrated energy from 140 to 240 microns, 10.3 nW/m^2/sr, is about twice
the integrated optical light from the galaxies in the Hubble Deep Field,
suggesting that star formation might have been heavily enshrouded by dust at
high redshift. The detections and upper limits reported here provide new
constraints on models of the history of energy-releasing processes and dust
production since the decoupling of the cosmic microwave background from matter.Comment: 26 pages and 5 figures, accepted for publication in the Astrophyical
Journa
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