Muon capture on nuclei with N > Z, random phase approximation, and in-medium renormalization of the axial-vector coupling constant

We use the random phase approximation to describe the muon capture rate on ${}^{44}$Ca,${}^{48}$Ca, ${}^{56}$Fe, ${}^{90}$Zr, and ${}^{208}$Pb. With ${}^{40}$Ca as a test case, we show that the Continuum Random Phase Approximation (CRPA) and the standard RPA give essentially equivalent descriptions of the muon capture process. Using the standard RPA with the free nucleon weak form factors we reproduce the experimental total capture rates on these nuclei quite well. Confirming our previous CRPA result for the $N = Z$ nuclei, we find that the calculated rates would be significantly lower than the data if the in-medium quenching of the axial-vector coupling constant were employed.Comment: submitted to Phys. Rev.

Short-range correlations in low-lying nuclear excited states

The electromagnetic transitions to various low-lying excited states of 16O, 48Ca and 208Pb are calculated within a model which considers the short-range correlations. In general the effects of the correlations are small and do not explain the required quenching to describe the data.Comment: 6 pages, 2 postscript figures, 1 tabl

The role of ν\nu-induced reactions on lead and iron in neutrino detectors

We have calculated cross sections and branching ratios for neutrino induced reactions on ^{208}Pb and ^{56}Fe for various supernova and accelerator-relevant neutrino spectra. This was motivated by the facts that lead and iron will be used on one hand as target materials in future neutrino detectors, on the other hand have been and are still used as shielding materials in accelerator-based experiments. In particular we study the inclusive ^{56}$Fe(\nu_e,e^-)$^{56}Co and ^{208}$Pb(\nu_e,e^-)$^{208}Bi cross sections and calculate the neutron energy spectra following the decay of the daughter nuclei. These reactions give a potential background signal in the KARMEN and LSND experiment and are discussed as a detection scheme for supernova neutrinos in the proposed OMNIS and LAND detectors. We also study the neutron-emission following the neutrino-induced neutral-current excitation of ^{56}Fe and ^{208}Pb.Comment: 23 pages (including 7 figures

Microhabitat use and spatial distribution in Picado’s Bromeliad Treefrog, Isthmohyla picadoi (Anura, Hylidae)

Isthmohyla picadoi is a Neotropical hylid frog found in upper humid montane forests of Costa Rica and Panama. The species is of particular interest because it continues to persist in an area in which the amphibian community has otherwise been decimated by the pathogenic fungus, Batrachochytrium dendrobatidis. Ground search, ladder climbing, and tree climbing techniques were used to locate 32 individuals; including adult males and females, juveniles, andmetamorphosing frogs. The majority of frogs were found in bromeliads, although some individuals were found on plants of the Euphorbiaceae, Musaceae, and Heliconiaceae families. Most frogs were found in larger bromeliads (45 cm or wider). There was a positive correlation between SUL and bromeliad width within the population but not within maturity classes (adult males, adult females, all adults, nonmetamorphosingjuveniles), suggesting that juvenile and adult frogs differ in bromeliad usage. Ranges of SUL and body weight in this particular population are much greater than those reported in previous species accounts

Corticotropin Releasing Factor Signaling in the Central Amygdala is Recruited during Binge-Like Ethanol Consumption in C57BL/6J Mice

A well-established body of work indicates a crucial role for corticotropin releasing factor (CRF) in neurobiological responses associated with excessive dependence-like ethanol drinking in ethanol vapor exposed rodents. Recent evidence demonstrates a role for CRF in the modulation of binge-like ethanol consumption by non-dependent mice, a behavior which can precede ethanol dependence. The CRF circuitry that is engaged by binge-like ethanol exposure, however, is unknown. Using converging approaches, we provide evidence that, similar to ethanol vapor-induced increases in ethanol intake, CRF signaling in the central nucleus of the amygdala (CeA) is engaged during binge-like ethanol consumption by C57BL/6J mice. Specifically, we found that binge-like consumption of an ethanol solution (20% ethanol v/v) was attenuated by pretreatment with the CRF1R antagonists antalarmin, (4-ethyl-[2,5,6-trimethyl-7-(2,4,6-trimethylphenyl)-7H-pyrrolo[2,3-d]pyrimidin-4-yl]amino-1-butanol (LWH-63), and NBI-27914 at doses (30 mg/kg, i.p.) that did not alter non-binge-like ethanol consumption. Binge-like ethanol consumption resulted in significant increases of CRF immunoreactivity in the CeA immediately following ethanol drinking and 18-24 h following ethanol removal and also blocked the ability of CRF to enhance GABAergic transmission in the CeA 18-24 h following ethanol removal. Pretreatment with bilateral injections of antalarmin (1 μg/ 0.5 μl per side) into the CeA, but not the adjacent basolateral amygdala (BLA), significantly attenuated binge-like ethanol consumption. These findings suggest that CRF signaling in the CeA is recruited during excessive ethanol intake, prior to the development of dependence. We hypothesize that plastic changes in CRF signaling develop with repeated binge-like drinking episodes, contributing to the transition to dependence

EFS shows biallelic methylation in uveal melanoma with poor prognosis as well as tissue-specific methylation

<p>Abstract</p> <p>Background</p> <p>Uveal melanoma (UM) is a rare eye tumor. There are two classes of UM, which can be discriminated by the chromosome 3 status or global mRNA expression profile. Metastatic progression is predominantly originated from class II tumors or from tumors showing loss of an entire chromosome 3 (monosomy 3). We performed detailed <it>EFS </it>(<it>embryonal Fyn-associated substrate</it>) methylation analyses in UM, cultured uveal melanocytes and normal tissues, to explore the role of the differentially methylated <it>EFS </it>promoter region CpG island in tumor classification and metastatic progression.</p> <p>Methods</p> <p><it>EFS </it>methylation was determined by direct sequencing of PCR products from bisulfite-treated DNA or by sequence analysis of individual cloned PCR products. The results were associated with clinical features of tumors and tumor-related death of patients.</p> <p>Results</p> <p>Analysis of 16 UM showed full methylation of the <it>EFS </it>CpG island in 8 (50%), no methylation in 5 (31%) and partial methylation in 3 (19%) tumors. Kaplan-Meier analysis revealed a higher risk of metastatic progression for tumors with <it>EFS </it>methylation (p = 0.02). This correlation was confirmed in an independent set of 24 randomly chosen tumors. Notably, only UM with <it>EFS </it>methylation gave rise to metastases. Real-time quantitative RT-PCR expression analysis revealed a significant inverse correlation of <it>EFS </it>mRNA expression with <it>EFS </it>methylation in UM. We further found that <it>EFS </it>methylation is tissue-specific with full methylation in peripheral blood cells, and no methylation in sperm, cultured primary fibroblasts and fetal muscle, kidney and brain. Adult brain samples, cultured melanocytes from the uveal tract, fetal liver and 3 of 4 buccal swab samples showed partial methylation. <it>EFS </it>methylation always affects both alleles in normal and tumor samples.</p> <p>Conclusions</p> <p>Biallelic <it>EFS </it>methylation is likely to be the result of a site-directed methylation mechanism. Based on partial methylation as observed in cultured melanocytes we hypothesize that there might be methylated and unmethylated precursor cells located in the uveal tract. The <it>EFS </it>methylation of a UM may depend on which type of precursor cell the tumor originated from.</p

CAG repeat length in the androgen receptor gene is related to age at diagnosis of prostate cancer and response to endocrine therapy, but not to prostate cancer risk

The length of the polymorphic CAG repeat in the N-terminal of the androgen receptor (AR) gene is inversely correlated with the transactivation function of the AR. Some studies have indicated that short CAG repeats are related to higher risk of prostate cancer. We performed a case–control study to investigate relations between CAG repeat length and prostate cancer risk, tumour grade, tumour stage, age at diagnosis and response to endocrine therapy. The study included 190 AR alleles from prostate cancer patients and 186 AR alleles from female control subjects. All were whites from southern Sweden. The frequency distribution of CAG repeat length was strikingly similar for cases and controls, and no significant correlation between CAG repeat length and prostate cancer risk was detected. However, for men with non-hereditary prostate cancer (n = 160), shorter CAG repeats correlated with younger age at diagnosis (P = 0.03). There were also trends toward associations between short CAG repeats and high grade (P = 0.07) and high stage (P = 0.07) disease. Furthermore, we found that patients with long CAG repeats responded better to endocrine therapy, even after adjusting for pretreatment level of prostate-specific antigen and tumour grade and stage (P = 0.05). We conclude that short CAG repeats in the AR gene correlate with young age at diagnosis of prostate cancer, but not with higher risk of the disease. Selection of patients with early onset prostate cancer in case–control studies could therefore lead to an over-estimation of the risk of prostate cancer for men with short CAG repeats. An association between long CAG repeats and good response to endocrine therapy was also found, but the mechanism and clinical relevance are unclear. © 1999 Cancer Research Campaig

Fractal assembly of micrometre-scale DNA origami arrays with arbitrary patterns

Self-assembled DNA nanostructures enable nanometre-precise patterning that can be used to create programmable molecular machines and arrays of functional materials. DNA origami is particularly versatile in this context because each DNA strand in the origami nanostructure occupies a unique position and can serve as a uniquely addressable pixel. However, the scale of such structures has been limited to about 0.05 square micrometres, hindering applications that demand a larger layout and integration with more conventional patterning methods. Hierarchical multistage assembly of simple sets of tiles can in principle overcome this limitation, but so far has not been sufficiently robust to enable successful implementation of larger structures using DNA origami tiles. Here we show that by using simple local assembly rules that are modified and applied recursively throughout a hierarchical, multistage assembly process, a small and constant set of unique DNA strands can be used to create DNA origami arrays of increasing size and with arbitrary patterns. We illustrate this method, which we term ‘fractal assembly’, by producing DNA origami arrays with sizes of up to 0.5 square micrometres and with up to 8,704 pixels, allowing us to render images such as the Mona Lisa and a rooster. We find that self-assembly of the tiles into arrays is unaffected by changes in surface patterns on the tiles, and that the yield of the fractal assembly process corresponds to about 0.95^(m − 1) for arrays containing m tiles. When used in conjunction with a software tool that we developed that converts an arbitrary pattern into DNA sequences and experimental protocols, our assembly method is readily accessible and will facilitate the construction of sophisticated materials and devices with sizes similar to that of a bacterium using DNA nanostructures