Brown University

About: Brown University is a education organization based out in Providence, Rhode Island, United States. It is known for research contribution in the topics: Population & Poison control. The organization has 35778 authors who have published 90896 publications receiving 4471489 citations. The organization is also known as: brown.edu & Brown.

A Self-Regulation Program for Maintenance of Weight Loss

Abstract: Background Since many successful dieters regain the weight they lose, programs that teach maintenance skills are needed. We developed a maintenance program based on self-regulation theory and tested the efficacy of delivering the program face to face or over the Internet. Methods We randomly assigned 314 participants who had lost a mean of 19.3 kg of body weight in the previous 2 years to one of three groups: a control group, which received quarterly newsletters (105 participants), a group that received face-to-face intervention (105), and a group that received Internet-based intervention (104). The content of the programs in the two intervention groups was the same, emphasizing daily self-weighing and self-regulation, as was the frequency of contact with the groups. The primary outcome was weight gain over a period of 18 months. Results The mean (±SD) weight gain was 2.5±6.7 kg in the face-to-face group, 4.7±8.6 kg in the Internet group, and 4.9±6.5 kg in the control group, with a significant difference ...

Genetic and epigenetic mechanisms in metal carcinogenesis and cocarcinogenesis: nickel, arsenic, and chromium.

Abstract: Chronic exposure to nickel(II), chromium(VI), or inorganic arsenic (iAs) has long been known to increase cancer incidence among affected individuals. Recent epidemiological studies have found that carcinogenic risks associated with chromate and iAs exposures were substantially higher than previously thought, which led to major revisions of the federal standards regulating ambient and drinking water levels. Genotoxic effects of Cr(VI) and iAs are strongly influenced by their intracellular metabolism, which creates several reactive intermediates and byproducts. Toxic metals are capable of potent and surprisingly selective activation of stress-signaling pathways, which are known to contribute to the development of human cancers. Depending on the metal, ascorbate (vitamin C) has been found to act either as a strong enhancer or suppressor of toxic responses in human cells. In addition to genetic damage via both oxidative and nonoxidative (DNA adducts) mechanisms, metals can also cause significant changes in DNA methylation and histone modifications, leading to epigenetic silencing or reactivation of gene expression. In vitro genotoxicity experiments and recent animal carcinogenicity studies provided strong support for the idea that metals can act as cocarcinogens in combination with nonmetal carcinogens. Cocarcinogenic and comutagenic effects of metals are likely to stem from their ability to interfere with DNA repair processes. Overall, metal carcinogenesis appears to require the formation of specific metal complexes, chromosomal damage, and activation of signal transduction pathways promoting survival and expansion of genetically/epigenetically altered cells.

Rapid screening method to detect potential biparental inheritance of plastid DNA and results for over 200 angiosperm species

Abstract: We have developed a diagnostic method to screen rapidly for plant species potentially capable of biparental inheritance ofplastid DNA using the DNA fluorochrome 4',6-diamidino-2-phenylindole (DAPI) in conjunction with epifluorescence microscopy. Pollen shed from 235 plant species (including about 50 of agronomic importance) representing 80 families were screened. Putative plastid DNA was detected in the generative and/or sperm cells of pollen from 26 genera (43 species) representing 15 families. Plastid DNA was not detected in the generative or sperm cells of pollen from 192 plant species, thereby strongly suggesting that these species have only maternal inheritance. Our cytological diagnosis corroborated the known genetic evidence in 42 plant species and conflicted with the genetic reports in five species, which are discussed. The data suggest that biparental inheritance of plastids is rare; overall, it may occur in about 14% of flowering plant genera, examples of which are scattered among 19% of the families examined. This methodology also readily reveals whether pollen is bi- or trinucleate.

Growing Y-junction carbon nanotubes

Abstract: The synthesis of connections between two or more different carbon nanotubes is an important step in the development of carbon nanotube-based electronic devices and circuits1,2,3,4. But this is difficult to achieve using conventional methods to grow carbon nanotubes5 because the straight tube structure cannot be controllably altered along its length. Various ideas for post-growth modifications have been suggested6, but these have been hard to implement and are prone to defects. Here we use nano-structured template channels to grow individual Y-junction carbon-nanotube heterostructures by the pyrolysis of acetylene with cobalt catalysis.

Packet Routing in Dynamically Changing Networks: A Reinforcement Learning Approach

Abstract: This paper describes the Q-routing algorithm for packet routing, in which a reinforcement learning module is embedded into each node of a switching network. Only local communication is used by each node to keep accurate statistics on which routing decisions lead to minimal delivery times. In simple experiments involving a 36-node, irregularly connected network, Q-routing proves superior to a nonadaptive algorithm based on precomputed shortest paths and is able to route efficiently even when critical aspects of the simulation, such as the network load, are allowed to vary dynamically. The paper concludes with a discussion of the tradeoff between discovering shortcuts and maintaining stable policies.