Spectroscopy of 19^{19}Ne for the thermonuclear 15^{15}O(α,γ\alpha,\gamma)19^{19}Ne and 18^{18}F(p,αp,\alpha)15^{15}O reaction rates

Uncertainties in the thermonuclear rates of the $^{15}$O($\alpha,\gamma$)$^{19}$Ne and $^{18}$F($p,\alpha$)$^{15}$O reactions affect model predictions of light curves from type I X-ray bursts and the amount of the observable radioisotope $^{18}$F produced in classical novae, respectively. To address these uncertainties, we have studied the nuclear structure of $^{19}$Ne over $E_{x} = 4.0 - 5.1$ MeV and $6.1 - 7.3$ MeV using the $^{19}$F($^{3}$He,t)$^{19}$Ne reaction. We find the $J^{\pi}$ values of the 4.14 and 4.20 MeV levels to be consistent with $9/2^{-}$ and $7/2^{-}$ respectively, in contrast to previous assumptions. We confirm the recently observed triplet of states around 6.4 MeV, and find evidence that the state at 6.29 MeV, just below the proton threshold, is either broad or a doublet. Our data also suggest that predicted but yet unobserved levels may exist near the 6.86 MeV state. Higher resolution experiments are urgently needed to further clarify the structure of $^{19}$Ne around the proton threshold before a reliable $^{18}$F($p,\alpha$)$^{15}$O rate for nova models can be determined.Comment: 5 pages, 3 figures, Phys. Rev. C (in press

An experimental investigation of the mechanical properties of a selected group of plastic materials

Dynamic and static testing of selected plastics for determination of mechanical propertie

Structure and evolutionary history of a large family of NLR proteins in the zebrafish

Multicellular eukaryotes have evolved a range of mechanisms for immune recognition. A widespread family involved in innate immunity are the NACHT-domain and leucine-rich-repeat-containing (NLR) proteins. Mammals have small numbers of NLR proteins, whereas in some species, mostly those without adaptive immune systems, NLRs have expanded into very large families. We describe a family of nearly 400 NLR proteins encoded in the zebrafish genome. The proteins share a defining overall structure, which arose in fishes after a fusion of the core NLR domains with a B30.2 domain, but can be subdivided into four groups based on their NACHT domains. Gene conversion acting differentially on the NACHT and B30.2 domains has shaped the family and created the groups. Evidence of positive selection in the B30.2 domain indicates that this domain rather than the leucine-rich repeats acts as the pathogen recognition module. In an unusual chromosomal organization, the majority of the genes are located on one chromosome arm, interspersed with other large multigene families, including a new family encoding zinc-finger proteins. The NLR-B30.2 proteins represent a new family with diversity in the specific recognition module that is present in fishes in spite of the parallel existence of an adaptive immune system

X-Ray Groups of Galaxies in the Aegis Deep and Wide Fields

We present the results of a search for extended X-ray sources and their corresponding galaxy groups from 800-ks Chandra coverage of the All-wavelength Extended Groth Strip International Survey (AEGIS). This yields one of the largest X-ray selected galaxy group catalogs from a blind survey to date. The red-sequence technique and spectroscopic redshifts allow us to identify 100$$ of reliable sources, leading to a catalog of 52 galaxy groups. The groups span the redshift range $z\sim0.066-1.544$ and virial mass range $M_{200}\sim1.34\times 10^{13}-1.33\times 10^{14}M_\odot$. For the 49 extended sources which lie within DEEP2 and DEEP3 Galaxy Redshift Survey coverage, we identify spectroscopic counterparts and determine velocity dispersions. We select member galaxies by applying different cuts along the line of sight or in projected spatial coordinates. A constant cut along the line of sight can cause a large scatter in scaling relations in low-mass or high-mass systems depending on the size of cut. A velocity dispersion based virial radius can more overestimate velocity dispersion in comparison to X-ray based virial radius for low mass systems. There is no significant difference between these two radial cuts for more massive systems. Independent of radial cut, overestimation of velocity dispersion can be created in case of existence of significant substructure and also compactness in X-ray emission which mostly occur in low mass systems. We also present a comparison between X-ray galaxy groups and optical galaxy groups detected using the Voronoi-Delaunay method (VDM) for DEEP2 data in this field.Comment: Accepted for publication in AP

The Chandra survey of the COSMOS field II: source detection and photometry

The Chandra COSMOS Survey (C-COSMOS) is a large, 1.8 Ms, Chandra program, that covers the central contiguous ~0.92 deg^2 of the COSMOS field. C-COSMOS is the result of a complex tiling, with every position being observed in up to six overlapping pointings (four overlapping pointings in most of the central ~0.45 deg^2 area with the best exposure, and two overlapping pointings in most of the surrounding area, covering an additional ~0.47 deg^2). Therefore, the full exploitation of the C-COSMOS data requires a dedicated and accurate analysis focused on three main issues: 1) maximizing the sensitivity when the PSF changes strongly among different observations of the same source (from ~1 arcsec up to ~10 arcsec half power radius); 2) resolving close pairs; and 3) obtaining the best source localization and count rate. We present here our treatment of four key analysis items: source detection, localization, photometry, and survey sensitivity. Our final procedure consists of a two step procedure: (1) a wavelet detection algorithm, to find source candidates, (2) a maximum likelihood Point Spread Function fitting algorithm to evaluate the source count rates and the probability that each source candidate is a fluctuation of the background. We discuss the main characteristics of this procedure, that was the result of detailed comparisons between different detection algorithms and photometry tools, calibrated with extensive and dedicated simulations.Comment: Accepted for publication in The Astrophysical Journal Supplement Serie

A New Spectroscopic and Photometric Analysis of the Transiting Planet Systems TrES-3 and TrES-4

We report new spectroscopic and photometric observations of the parent stars of the recently discovered transiting planets TrES-3 and TrES-4. A detailed abundance analysis based on high-resolution spectra yields [Fe/H] $= -0.19\pm 0.08$, $T_\mathrm{eff} = 5650\pm 75$ K, and $\log g = 4.4\pm 0.1$ for TrES-3, and [Fe/H] $= +0.14\pm 0.09$, $T_\mathrm{eff} = 6200\pm 75$ K, and $\log g = 4.0\pm0.1$ for TrES-4. The accuracy of the effective temperatures is supported by a number of independent consistency checks. The spectroscopic orbital solution for TrES-3 is improved with our new radial-velocity measurements of that system, as are the light-curve parameters for both systems based on newly acquired photometry for TrES-3 and a reanalysis of existing photometry for TrES-4. We have redetermined the stellar parameters taking advantage of the strong constraint provided by the light curves in the form of the normalized separation $a/R_\star$ (related to the stellar density) in conjunction with our new temperatures and metallicities. The masses and radii we derive are M_\star=0.928_{-0.048}^{+0.028} M_{\sun},R_\star = 0.829_{-0.022}^{+0.015} R_{\sun}, and M_\star = 1.404_{-0.134}^{+0.066} M_{\sun}, R_\star=1.846_{-0.087}^{+0.096} R_{\sun} for TrES-3 and TrES-4, respectively. With these revised stellar parameters we obtain improved values for the planetary masses and radii. We find $M_p = 1.910_{-0.080}^{+0.075} M_\mathrm{Jup}$, $R_p=1.336_{-0.036}^{+0.031} R_\mathrm{Jup}$ for TrES-3, and $M_p=0.925 \pm 0.082 M_\mathrm{Jup}$, $R_p=1.783_{-0.086}^{+0.093} R_\mathrm{Jup}$ for TrES-4. We confirm TrES-4 as the planet with the largest radius among the currently known transiting hot Jupiters.Comment: 42 pages, 10 tables, 8 figures. Accepted for publication in the Astrophysical Journa

Electrically driven single electron spin resonance in a slanting Zeeman field

The rapidly rising fields of spintronics and quantum information science have led to a strong interest in developing the ability to coherently manipulate electron spins. Electron spin resonance (ESR) is a powerful technique to manipulate spins that is commonly achieved by applying an oscillating magnetic field. However, the technique has proven very challenging when addressing individual spins. In contrast, by mixing the spin and charge degrees of freedom in a controlled way through engineered non-uniform magnetic fields, electron spin can be manipulated electrically without the need of high-frequency magnetic fields. Here we realize electrically-driven addressable spin rotations on two individual electrons by integrating a micron-size ferromagnet to a double quantum dot device. We find that the electrical control and spin selectivity is enabled by the micro-magnet's stray magnetic field which can be tailored to multi-dots architecture. Our results demonstrate the feasibility of manipulating electron spins electrically in a scalable way.Comment: 25 pages, 6 figure

Is \gamma-ray emission from novae affected by interference effects in the 18F(p,\alpha)15O reaction?

The 18F(p,\alpha)15O reaction rate is crucial for constraining model predictions of the \gamma-ray observable radioisotope 18F produced in novae. The determination of this rate is challenging due to particular features of the level scheme of the compound nucleus, 19Ne, which result in interference effects potentially playing a significant role. The dominant uncertainty in this rate arises from interference between J\pi=3/2+ states near the proton threshold (Sp = 6.411 MeV) and a broad J\pi=3/2+ state at 665 keV above threshold. This unknown interference term results in up to a factor of 40 uncertainty in the astrophysical S-factor at nova temperatures. Here we report a new measurement of states in this energy region using the 19F(3He,t)19Ne reaction. In stark contrast with previous assumptions we find at least 3 resonances between the proton threshold and Ecm=50 keV, all with different angular distributions. None of these are consistent with J\pi= 3/2+ angular distributions. We find that the main uncertainty now arises from the unknown proton-width of the 48 keV resonance, not from possible interference effects. Hydrodynamic nova model calculations performed indicate that this unknown width affects 18F production by at least a factor of two in the model considered.Comment: 5 pages, 4 figures. Accepted for publication in Phys. Rev. Let

DNA methylation analysis by digital bisulfite genomic sequencing and digital MethyLight

Alterations in cytosine-5 DNA methylation are frequently observed in most types of human cancer. Although assays utilizing PCR amplification of bisulfite-converted DNA are widely employed to analyze these DNA methylation alterations, they are generally limited in throughput capacity, detection sensitivity, and or resolution. Digital PCR, in which a DNA sample is analyzed in distributive fashion over multiple reaction chambers, allows for enumeration of discrete template DNA molecules, as well as sequestration of non-specific primer annealing templates into negative chambers, thereby increasing the signal-to-noise ratio in positive chambers. Here, we have applied digital PCR technology to bisulfite-converted DNA for single-molecule high-resolution DNA methylation analysis and for increased sensitivity DNA methylation detection. We developed digital bisulfite genomic DNA sequencing to efficiently determine single-basepair DNA methylation patterns on single-molecule DNA templates without an interim cloning step. We also developed digital MethyLight, which surpasses traditional MethyLight in detection sensitivity and quantitative accuracy for low quantities of DNA. Using digital MethyLight, we identified single-molecule, cancer-specific DNA hypermethylation events in the CpG islands of RUNX3, CLDN5 and FOXE1 present in plasma samples from breast cancer patients