Disk Properties and Density Structure of the Star-Forming Dense Core B335

We present subarcsecond resolution dust continuum observations of the protostellar collapse candidate B335 made with the IRAM Plateau de Bure Interferometer at wavelengths of 1.2 and 3.0 mm. These observations probe to < 100 AU size scales and reveal a compact source component that we identify with a circumstellar disk. We analyze these data in concert with previous lower resolution interferometer observations and find a best fit density structure for B335 that consists of a power law envelope with index p=1.55 +/- 0.04 (r < 5000 AU) together with a disk (r < 100 AU) of flux F_{1.2 mm}=21 +/-2 mJy. We estimate a systematic uncertainty in the power law index delta(p) < 0.15, where the largest error comes from the assumed form of the dust temperature falloff with radius. This determination of the inner density structure of B335 has a precision unique amongst protostellar cores, and it is consistent with the r^{-1.5} profile of gravitational free-fall, in accord with basic expectations for the formation of a star. The flux (and implied mass) of the compact component in B335 is typical of the disks around T Tauri stars.Comment: 16 pages, 2 figures. Accepted to the Astrophysical Journal, sched v596 (2003 Oct 10

Regulation of UGT1A1 and HNF1 transcription factor gene expression by DNA methylation in colon cancer cells

<p>Abstract</p> <p>Background</p> <p>UDP-glucuronosyltransferase 1A1 (UGT1A1) is a pivotal enzyme involved in metabolism of SN-38, the active metabolite of irinotecan commonly used to treat metastatic colorectal cancer. We previously demonstrated aberrant methylation of specific CpG dinucleotides in UGT1A1-negative cells, and revealed that methylation state of the <it>UGT1A1 </it>5'-flanking sequence is negatively correlated with gene transcription. Interestingly, one of these CpG dinucleotides (CpG -4) is found close to a HNF1 response element (HRE), known to be involved in activation of <it>UGT1A1 </it>gene expression, and within an upstream stimulating factor (USF) binding site.</p> <p>Results</p> <p>Gel retardation assays revealed that methylation of CpG-4 directly affect the interaction of USF1/2 with its cognate sequence without altering the binding for HNF1-alpha. Luciferase assays sustained a role for USF1/2 and HNF1-alpha in <it>UGT1A1 </it>regulation in colon cancer cells. Based on the differential expression profiles of <it>HNF1A </it>gene in colon cell lines, we also assessed whether methylation affects its expression. In agreement with the presence of CpG islands in the <it>HNF1A </it>promoter, treatments of UGT1A1-negative HCT116 colon cancer cells with a DNA methyltransferase inhibitor restore <it>HNF1A </it>gene expression, as observed for <it>UGT1A1</it>.</p> <p>Conclusions</p> <p>This study reveals that basal <it>UGT1A1 </it>expression in colon cells is positively regulated by HNF1-alpha and USF, and negatively regulated by DNA methylation. Besides, DNA methylation of <it>HNF1A </it>could also play an important role in regulating additional cellular drug metabolism and transporter pathways. This process may contribute to determine local inactivation of drugs such as the anticancer agent SN-38 by glucuronidation and define tumoral response.</p

The use of ecosystem-based adaptation practices by smallholder farmers in Central America

There is growing interest in promoting the use of Ecosystem-based Adaptation (EbA) practices to help smallholder farmers adapt to climate change, however there is limited information on how commonly these practices are used by smallholder farmers and what factors influence their use. Using participatory mapping and field surveys, we examined the prevalence and characteristics of EbA practices on 300 smallholder coffee and maize farmers in six landscapes in Central America and explored the socioeconomic and biophysical factors associated with their use. The prevalence of individual EbA practices varied across smallholder farms. Common EbA practices included live fences, home gardens, shade trees in coffee plantations, and dispersed trees in maize fields. We found a mean of 3.8 EbA practices per farm. Factors that were correlated with the total number of EbA practices on farms included the mean area of coffee plantations, farmer age, farmer experience, the farm type and the landscape in which farms were located. Factors associated with the presence or characteristics of individual EbA practices included the size of coffee plantations, farmer experience, farmer education, land tenure, landscape and farm type. Our analysis suggests that many smallholder farmers in Central America are already using certain EbA practices, but there is still scope for greater implementation. Policy makers, donors and technicians can encourage the broader use of EbA by smallholder farmers by facilitating farmer-to-farmer exchanges to share knowledge on EbA implementation, assessing the effectiveness of EbA practices in delivering adaptation benefits, and tailoring EbA policies and programs for smallholder farmers in different socioeconomic and biophysical contexts. (Résumé d'auteur

UGT genomic diversity : beyond gene duplication

The human uridine diphospho (UDP)-glucuronosyltransferase (UGT) superfamily comprises enzymes responsible for a major biotransformation phase II pathway: the glucuronidation process. The UGT enzymes are located in the endoplasmic reticulum of almost all tissues, where they catalyze the inactivation of several endogenous and exogenous molecules, including bilirubin, sex steroids, numerous prescribed drugs, and environmental toxins. This metabolic pathway is particularly variable. The influence of inheritable polymorphisms in human UGT-encoding genes has been extensively documented and was shown to be responsible for a fraction of the observed phenotypic variability. Other key genomic processes are likely underlying this diversity; these include copy-number variations, epigenetic factors, and newly discovered splicing mechanisms. This review will discuss novel molecular aspects that may be determinant to UGT phenotypes

Reservas de biomasa de árboles dispersos en potreros y mitigación al cambio climático.

El presente estudio tuvo como objetivo determinar la contribución de los árboles en potreros a la mitigación al cambio climático mediante la estimación de las reservas de carbono en Costa Rica y Nicaragua. Entre los años 2002 y 2003, 17 783 árboles fueron inventariados en potreros de 59 fincas ubicadas en zonas de bosque tropical seco, húmedo y seco con transición a húmedo. El valor promedio de las reservas de biomasa de los árboles en los potreros fue de 10,7±1,1 Mg/ha con un valor mínimo de 5,3±1 Mg/ha en Rivas y un máximo de 13,5±3,5 Mg/ha en Matiguás. Existe relación entre la biomasa arriba del suelo de los potreros con la densidad árboles y el área basal, lo que permitió desarrollar ecuaciones simples para predecir dichos cambios. El diseño de políticas que incentiven la conservación y manejo de árboles en potreros, será un aspecto clave a ser incorporado dentro de las estrategias de cambio climático de los países

Inner Structure of Protostellar Collapse Candidate B335 Derived from Millimeter-Wave Interferometry

We present a study of the density structure of the protostellar collapse candidate B335 using continuum observations from the IRAM Plateau de Bure Interferometer made at wavelengths of 1.2mm and 3.0mm. We analyze these data, which probe spatial scales from 5000 AU to 500 AU, directly in the visibility domain by comparison to synthetic observations constructed from models that assume different physical conditions. This approach allows for much more stringent constraints to be derived from the data than from analysis of images. A single radial power law in density provides a good description of the data, with best fit power law index p=1.65+/-0.05. Through simulations, we quantify the sensitivity of this result to various model uncertainties, including assumptions of temperature distribution, outer boundary, dust opacity spectral index, and an unresolved central component. The largest uncertainty comes from the unknown presence of a centralized point source. A point source with 1.2mm flux of F=12+/-7 mJy reduces the density index to p=1.47+/-0.07. The remaining sources of systematic uncertainty, the most important of which is the temperature distribution, likely contribute a total uncertainty of < 0.2. We therefore find strong evidence that the power law index of the density distribution within 5000 AU is significantly less than the value at larger radii, close to 2.0 from previous studies of dust emission and extinction. These results conform well to the generic paradigm of isolated, low-mass star formation which predicts a power law density index close to p=1.5 for an inner region of gravitational free fall onto the protostar.Comment: Accepted to the Astrophysical Journal; 27 pages, 3 figure

Can we improve pain and sleep in elderly individuals with transcranial direct current stimulation? : results from a randomized controlled pilot study

Abstract : Background: The prevalence of chronic pain and sleep disturbances substantially increases with age. Pharmacotherapy remains the primary treatment option for these health issues. However, side effects and drug interactions are difficult to control in elderly individuals. Aims: The objective of this study was to assess the feasibility of conducting a randomized sham-controlled trial and to collect preliminary data on the efficacy of transcranial direct current stimulation (tDCS) to reduce pain and improve sleep in older adults suffering from chronic pain. Methods: Fourteen elderly individuals (mean age 71±7 years) suffering from chronic pain and sleep complaints were randomized to receive either anodal tDCS, applied over the primary motor cortex (2 mA, 20 minutes), or sham tDCS, for 5 consecutive days. Pain was measured with visual analog scales, pain logbooks and questionnaires, while sleep was assessed with actigraphy, sleep diaries and questionnaires. Results: There were no missing data for pain and sleep measures, except for actigraphy, that generated several missing data. Blinding was maintained throughout the study, for both the evaluator and participants. Active but not sham tDCS significantly reduced pain (P or =0.18). Conclusion: The present study provides guidelines for the implementation of future tDCS studies in larger populations of elderly individuals. M1 anodal tDCS in this population appears to be effective to reduce pain, but not to improve sleep

Benchmark: using sensors to study public space

Efforts have been made throughout history to measure how people use public space. This research seeks to integrate a range of sensor technologies to automate analysis of pedestrian usage of public space. A range of environmental sensors, image recognition utilities, and open-source software are combined to create a system to measure in detail how people use public space, with the intention of serving as a tool for creating better public spaces in the future. This framework is part of a broader effort to offer organizations and individuals methods and data to inform place-making interventions at multiple scales in conjunction with the Gehl Institute and Better Block Foundation