Pointing Control and Stabilization of the High-Energy UV Laser for Laser-Assisted Charge Exchange

Laser-Assisted Charge Exchange (LACE) is an experimental method of charge exchange injection into a proton accumulator ring that is being developed at the Spallation Neutron Source (SNS) in Oak Ridge National Laboratory (ORNL) as an alternative to hazardous injection foils. The current scheme of LACE requires a high-energy, low-repetition-rate UV (355 nm) laser beam (140 mJ pulses at 10 Hz) to be transported over 65 meters to the laser-particle interaction point (IP) in a high-radiation area of the accelerator. Thermal effects and other disturbances along the free-space laser transport line cause the beam to slowly drift away from the IP and jitter at a frequency comparable to the pulse repetition rate. A control system was designed, simulated, and constructed to stabilize the pointing of the laser beam to allow stable operation of the experiment. The laser pointing stabilization system is based on feedback between Complementary Metal-Oxide-Semiconductor (CMOS) cameras and a steering mirror with piezoelectric actuators. A PC running custom-made LabVIEW software acts a controller in open- and closed-loop modes, as well as a diagnostic tool. An analytical model of the system was used for optimization of the control law, and the system performs as well in the field as it did in laboratory tests. The laser pointing stabilization system eliminates the slow drift by keeping the beam aligned at the IP for an indefinite amount of time, and the jitter is reduced to the level of the pulse-to-pulse fluctuations

Kepler Presearch Data Conditioning II - A Bayesian Approach to Systematic Error Correction

With the unprecedented photometric precision of the Kepler Spacecraft, significant systematic and stochastic errors on transit signal levels are observable in the Kepler photometric data. These errors, which include discontinuities, outliers, systematic trends and other instrumental signatures, obscure astrophysical signals. The Presearch Data Conditioning (PDC) module of the Kepler data analysis pipeline tries to remove these errors while preserving planet transits and other astrophysically interesting signals. The completely new noise and stellar variability regime observed in Kepler data poses a significant problem to standard cotrending methods such as SYSREM and TFA. Variable stars are often of particular astrophysical interest so the preservation of their signals is of significant importance to the astrophysical community. We present a Bayesian Maximum A Posteriori (MAP) approach where a subset of highly correlated and quiet stars is used to generate a cotrending basis vector set which is in turn used to establish a range of "reasonable" robust fit parameters. These robust fit parameters are then used to generate a Bayesian Prior and a Bayesian Posterior Probability Distribution Function (PDF) which when maximized finds the best fit that simultaneously removes systematic effects while reducing the signal distortion and noise injection which commonly afflicts simple least-squares (LS) fitting. A numerical and empirical approach is taken where the Bayesian Prior PDFs are generated from fits to the light curve distributions themselves.Comment: 43 pages, 21 figures, Submitted for publication in PASP. Also see companion paper "Kepler Presearch Data Conditioning I - Architecture and Algorithms for Error Correction in Kepler Light Curves" by Martin C. Stumpe, et a

Natural Flood Management Through Peatland Restoration: : Catchment-Scale Modeling of Past and Future Scenarios in Glossop, UK

Peer reviewe

COL4A3 expression in asthmatic epithelium depends on intronic methylation and ZNF263 binding.

Background Reduction of COL4A3, one of the six isoforms of collagen 4, in asthmatic airways results in increased inflammation and angiogenesis, implicating it as a central part of asthma pathogenesis. However, to date, the path underlying these diminished COL4A3 levels has been elusive. This study investigated a possible mechanism underlying the reduction of COL4A3 expression. Methods Bronchial biopsies of 76 patients with asthma and 83 controls were subjected to RNA-sequencing and DNA methylation bead arrays to identify expression and methylation changes. The binding of ZNF263 was analysed by chromatin-immunoprecipitation sequencing coupled with quantitative (q)PCR. Effects of ZNF263 silencing, using small interfering RNA, on the COL4A3 expression were studied using qPCR. Results COL4A3 expression was significantly reduced in bronchial biopsies compared to healthy controls, whereas DNA methylation levels at cg11797365 were increased. COL4A3 expression levels were significantly low in asthmatics without inhaled corticosteroid (ICS) use, whereas the expression was not statistically different between asthmatics using ICS and controls. Methylation levels at cg11797365 in vitro were increased upon consecutive rhinovirus infections. Conclusion Our data indicate an epigenetic modification as a contributing factor for the loss of COL4A3 expression in asthmatic airway epithelium

The role of minor mergers in the recent star formation history of early-type galaxies

We demonstrate that the large scatter in the ultra-violet (UV) colours of intermediate-mass early-type galaxies in the local Universe and the inferred low-level recent star formation in these objects can be reproduced by minor mergers in the standard LCDM cosmology. Numerical simulations of mergers with mass ratios less than or equal to 1:4, with reasonable assumptions for the ages, metallicities and dust properties of the merger progenitors, produce good agreement to the observed UV colours of the early-type population, if the infalling satellites are assumed to have (cold) gas fractions greater than 20%. Early-types that satisfy (NUV-r) < 3.8 are likely to have experienced mergers with mass ratios between 1:4 and 1:6 within the last ~1.5 Gyrs, while those that satisfy 3.8<(NUV-r)<5.5 are consistent with either recent mergers with mass ratios < 1:6 or mergers with higher mass ratios that occurred more than ~1.5 Gyrs in the past. We demonstrate that the early-type colour-magnitude relations and colour distributions in both the UV and optical spectral ranges are consistent with the expected frequency of minor merging activity in the standard LCDM cosmology at low redshift. We present a strong plausibility argument for minor mergers to be the principal mechanism behind the large UV scatter and associated low-level recent star formation observed in early-type galaxies in the nearby Universe.Comment: MNRAS in pres

Decision-Directed Channel Estimation Implementation for Spectral Efficiency Improvement in Mobile MIMO-OFDM

Channel estimation algorithms and their implementations for mobile receivers are considered in this paper. The 3GPP long term evolution (LTE) based pilot structure is used as a benchmark in a multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) receiver. The decision directed (DD) space alternating generalized expectation-maximization (SAGE) algorithm is used to improve the performance from that of the pilot symbol based least-squares (LS) channel estimator. The performance is improved with high user velocities, where the pilot symbol density is not sufficient. Minimum mean square error (MMSE) filtering is also used in estimating the channel in between pilot symbols. The pilot overhead can be reduced to a third of the LTE pilot overhead with DD channel estimation, obtaining a ten percent increase in data throughput. Complexity reduction and latency issues are considered in the architecture design. The pilot based LS, MMSE and the SAGE channel estimators are implemented with a high level synthesis tool, synthesized with the UMC 0.18 μm CMOS technology and the performance-complexity trade-offs are studied. The MMSE estimator improves the performance from the simple LS estimator with LTE pilot structure and has low power consumption. The SAGE estimator has high power consumption but can be used with reduced pilot density to increase the data rate.National Science FoundationTekesElektrobitRenesas Mobile EuropeAcademy of FinlandNokia Siemens NetworksXilin

Nonsteroidal anti-inflammatory drugs, apoptosis, and colorectal adenomas

AbstractBackground & Aims: Observational studies indicate that nonsteroidal anti-inflammatory drugs (NSAIDs) reduce the risk of colorectal neoplasia. The mechanism of this effect could be via modification of apoptotic activity in colonic mucosa. We examined grossly normal rectal mucosa in patients with adenomas and adenoma-free controls to assess the associations between NSAID use, adenomatous polyps, and apoptosis. Methods: Study participants were drawn from consecutive patients who underwent colonoscopy between August, 1998, and February, 2000. Biopsy specimens were taken from normal-appearing rectal mucosa 10 cm from the anal verge. Apoptosis was scored from coded, H&E-stained sections using morphologic methods. Proliferation was scored using whole crypt mitotic counts. Univariate and multivariate regression analyses were conducted to estimate crude and adjusted odds ratios (ORs). Results: There were 226 patients with adenomas and 493 adenoma-free controls. After adjusting for sex, age, race, and body mass index (BMI), individuals in the highest tertile of regular NSAID use were substantially less likely to have adenomas (OR 0.4; 95% CI: 0.2–0.7) compared with occasional or nonusers. Similarly, compared with the lowest tertile, persons in the highest tertile of rectal mucosal apoptotic activity were much less likely to have adenomas (OR 0.12; 95% CI: 0.07–0.20). NSAID use and apoptotic activity were not correlated (r = 0.10). Mucosal proliferation was not related to adenomas or NSAID use. Conclusions: Our observations suggest that NSAID use and higher levels of mucosal apoptosis are independently associated with a lower prevalence of adenomas. The study shows a strong field effect for apoptosis.GASTROENTEROLOGY 2002;123:1770-177

Suppressor of cytokine signaling 3 (SOCS3) is not an independent biomarker of colorectal adenoma risk

<p>Abstract</p> <p>Background</p> <p>Inflammation and its associated pathologies are increasingly suggested as risk factors for colorectal cancer (CRC) development. Previous research from our group has shown that increased levels of circulating, pro-inflammatory cytokines IL-6 and TNFα promote colorectal adenoma risk. Emerging data in mice and humans suggest that Suppressor of Cytokine Signaling 3 (SOCS3) may act as a tumor suppressor in the intestine, and decreased SOCS3 expression may promote CRC. As SOCS3 has been shown to inhibit the actions of IL-6 and TNFα in the intestine, we hypothesized that decreased SOCS3 expression in normal mucosa may predispose to adenomas and thus increase risk for CRC.</p> <p>Findings</p> <p>We examined SOCS3 mRNA levels in normal mucosa biopsies of 322 screening colonoscopy patients (93 with adenoma and 229 without adenoma) using real-time qRT-PCR. Logistic regression analysis was used to generate odds ratios (OR) and 95% confidence intervals to determine if low SOCS3 expression was associated with adenoma status. Median SOCS3 values did not differ between patients with or without adenoma. Logistic regression analysis showed no association (unadjusted or adjusted for age and sex) between SOCS3 and colorectal adenomas.</p> <p>Conclusions</p> <p>Low SOCS3 mRNA expression is not an independent biomarker of colorectal adenoma risk in the normal mucosa. SOCS3 silencing likely occurs later in CRC progression.</p

Blowing cold flows away: the impact of early AGN activity on the formation of a brightest cluster galaxy progenitor

Supermassive black holes (BH) are powerful sources of energy that are already in place at very early epochs of the Universe (by z=6). Using hydrodynamical simulations of the formation of a massive M_vir=5 10^11 M_sun halo by z=6 (the most massive progenitor of a cluster of M_vir=2 10^15 M_sun at z=0), we evaluate the impact of Active Galactic Nuclei (AGN) on galaxy mass content, BH self-regulation, and gas distribution inside this massive halo. We find that SN feedback has a marginal influence on the stellar structure, and no influence on the mass distribution on large scales. In contrast, AGN feedback alone is able to significantly alter the stellar-bulge mass content by quenching star formation when the BH is self-regulating, and by depleting the cold gas reservoir in the centre of the galaxy. The growth of the BH proceeds first by a rapid Eddington-limited period fed by direct cold filamentary infall. When the energy delivered by the AGN is sufficiently large to unbind the cold gas of the bulge, the accretion of gas onto the BH is maintained both by smooth gas inflow and clump migration through the galactic disc triggered by merger-induced torques. The feedback from the AGN has also a severe consequence on the baryon mass content within the halo, producing large-scale hot superwinds, able to blow away some of the cold filamentary material from the centre and reduce the baryon fraction by more than 30 per cent within the halo's virial radius. Thus in the very young universe, AGN feedback is likely to be a key process, shaping the properties of the most massive galaxies.Comment: 18 pages, 16 figures, MNRAS accepte

Ternary structure reveals mechanism of a membrane diacylglycerol kinase

Diacylglycerol kinase catalyses the ATP-dependent conversion of diacylglycerol to phosphatidic acid in the plasma membrane of Escherichia coli. The small size of this integral membrane trimer, which has 121 residues per subunit, means that available protein must be used economically to craft three catalytic and substrate-binding sites centred about the membrane/cytosol interface. How nature has accomplished this extraordinary feat is revealed here in a crystal structure of the kinase captured as a ternary complex with bound lipid substrate and an ATP analogue. Residues, identified as essential for activity by mutagenesis, decorate the active site and are rationalized by the ternary structure. The g-phosphate of the ATP analogue is positioned for direct transfer to the primary hydroxyl of the lipid whose acyl chain is in the membrane. A catalytic mechanism for this unique enzyme is proposed. The active site architecture shows clear evidence of having arisen by convergen