5,819 research outputs found

    Voigt-Profile Analysis of the Lyman-alpha Forest in a Cold Dark Matter Universe

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    We use an automated Voigt-profile fitting procedure to extract statistical properties of the Lyα\alpha forest in a numerical simulation of an Ω=1\Omega=1, cold dark matter (CDM) universe. Our analysis method is similar to that used in most observational studies of the forest, and we compare the simulations to recently published results derived from Keck HIRES spectra. With the Voigt-profile decomposition analysis, the simulation reproduces the large number of weak lines (N_{\rm HI}\la 10^{13}\cdunits) found in the HIRES spectra. The column density distribution evolves significantly between z=3z=3 and z=2z=2, with the number of lines at fixed column density dropping by a factor ∼1.6\sim 1.6 in the range where line blending is not severe. At z=3z=3, the bb-parameter distribution has a median of 35 \kms and a dispersion of 20 \kms, in reasonable agreement with the observed values. The comparison between our new analysis and recent data strengthens earlier claims that the \lya forest arises naturally in hierarchical structure formation as photoionized gas falls into dark matter potential wells. However, there are two statistically signficant discrepancies between the simulated forest and the HIRES results: the model produces too many lines at z=3z=3 by a factor ∼1.5−2\sim 1.5-2, and it produces more narrow lines (b<20 \kms) than are seen in the data. The first result is sensitive to our adopted normalization of the mean \lya optical depth, and the second is sensitive to our assumption that helium reionization has not significantly raised gas temperatures at z=3z=3. It is therefore too early to say whether these discrepancies indicate a fundamental problem with the high-redshift structure of the Ω=1\Omega=1 CDM model or reflect errors of detail in our modeling of the gas distribution or the observational procedure.Comment: 13 pages, 3 figures, AAS LaTex, accepted to Ap

    Comparative of Stock Price Before and After Indonesian Presidential Election in 2014 of Lq-45 Stock Listed on Idx

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    Recently, investors have knowledge on investment for their future benefits. Then, as time goes by, they found out that information about some events may have a significant influence on the performance of the stock price and it makes them worry if this kind of event could affect the price of their shares, especially the price of LQ-45 stocks. One of the events that may affect the stock price is presidential election because it is macroeconomics factor that affect all aspects in the country including investment. This research conducted to identify the significant change of the stock price and to know if this event has an effect on price of LQ-45 Stock. This research uses Time Series Analysis, Paired Sample t-Test and purposive sampling method where the sample of this research is all LQ-45 stocks in IDX. The correlation result finds that there is a relation between stock price and presidential election. There is also a significant change on stock price after the presidential election. Therefore, it concluded that event such as presidential election is one of the factors that affect the performance of the stock price and investors recommended to be more cautious of information while doing stock transaction, and makes better investment. Keywords: stock price, presidential election, event stud

    Drug-Phospholipid Complex-loaded Matrix Film Formulation for the Enhanced Transdermal Delivery of Quercetin

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    A novel quercetin-phospholipid-complex(QPLC)-loaded matrix film for improved transdermal delivery of quercetin was developed. The QPLC formulation, prepared using a solvent-evaporation method, was optimized using a central-composite design. The optimized QPLC formulation was characterized by particle size and zeta potential analysis, thermal analysis, Fourier transform infrared spectroscopy (FTIR), and proton nuclear magnetic resonance spectroscopy (1H-NMR). QPLC formulation was functionally evaluated for solubility and in vitro dissolution of quercetin. Matrix films of pure quercetin (Q-MF)or QPLC QPLC-MF) were prepared using a solvent casting method. The prepared Q-MF and QPLC-MF were characterized for weight uniformity, folding endurance, moisture content, and moisture uptake. The films were also functionally characterized for in vitro diffusion of quercetin through a dialysis membrane and ex vivo permeability of quercetin across rat skin. Finally, the anti-inflammatory activity of the films was evaluated on carrageenan-induced paw edema in Wistar albino rats. The experimental design identified the optimal formulation and process variables for the preparation of QPLC. The validation of the obtained model using these values confirmed the suitability and robustness of the model. The physical-chemical characterization of the prepared QPLC supported the formation of a stable complex. The solubility analysis of QPLC showed a 22-fold increase in quercetin aqueous solubility, compared to pure quercetin. The dissolution results exhibited a significantly higher rate and extent of quercetin dissolution from QPLC compared to that of pure quercetin. The permeability of quercetin from Q-MF and QPLC-MF across rat skin mirrored those obtained from the dissolution studies. Topical application of QPLC-MF exhibited a significant (p\u3c0.05) inhibition of carrageenan-induced paw edema in rats compared to that of Q-MF. This study provides a promising combination approach, i.e., phospholipid-based complexation and transdermal film formulation for improved transdermal delivery of quercetin and similar pharmacologically active phytoconstituents

    Quantifying methane and nitrous oxide emissions from the UK and Ireland using a national-scale monitoring network

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    The UK is one of several countries around the world that has enacted legislation to reduce its greenhouse gas emissions. In this study, we present top-down emissions of methane (CH4) and nitrous oxide (N2O) for the UK and Ireland over the period August 2012 to August 2014. These emissions were inferred using measurements from a network of four sites around the two countries. We used a hierarchical Bayesian inverse framework to infer fluxes as well as a set of covariance parameters that describe uncertainties in the system. We inferred average UK total emissions of 2.09 (1.65–2.67) Tg yr−1 CH4 and 0.101 (0.068–0.150) Tg yr−1 N2O and found our derived UK estimates to be generally lower than the a priori emissions, which consisted primarily of anthropogenic sources and with a smaller contribution from natural sources. We used sectoral distributions from the UK National Atmospheric Emissions Inventory (NAEI) to determine whether these discrepancies can be attributed to specific source sectors. Because of the distinct distributions of the two dominant CH4 emissions sectors in the UK, agriculture and waste, we found that the inventory may be overestimated in agricultural CH4 emissions. We found that annual mean N2O emissions were consistent with both the prior and the anthropogenic inventory but we derived a significant seasonal cycle in emissions. This seasonality is likely due to seasonality in fertilizer application and in environmental drivers such as temperature and rainfall, which are not reflected in the annual resolution inventory. Through the hierarchical Bayesian inverse framework, we quantified uncertainty covariance parameters and emphasized their importance for high-resolution emissions estimation. We inferred average model errors of approximately 20 and 0.4 ppb and correlation timescales of 1.0 (0.72–1.43) and 2.6 (1.9–20 3.9) days for CH4 and N2O, respectively. These errors are a combination of transport model errors as well as errors due to unresolved emissions processes in the inventory. We found the largest CH4 errors at the Tacolneston station in eastern England, which may be due to sporadic emissions from landfills and offshore gas in the North Sea

    Cooling Radiation and the Lyman-alpha Luminosity of Forming Galaxies

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    We examine the cooling radiation from forming galaxies in hydrodynamic simulations of the LCDM model (cold dark matter with a cosmological constant), focusing on the Ly-alpha line luminosities of high-redshift systems. Primordial composition gas condenses within dark matter potential wells, forming objects with masses and sizes comparable to the luminous regions of observed galaxies. As expected, the energy radiated in this process is comparable to the gravitational binding energy of the baryons, and the total cooling luminosity of the galaxy population peaks at z ~= 2. However, in contrast to the classical picture of gas cooling from the \sim 10^6 K virial temperature of a typical dark matter halo, we find that most of the cooling radiation is emitted by gas with T < 20,000 K. As a consequence, roughly 50% of this cooling radiation emerges in the Ly-alpha line. While a galaxy's cooling luminosity is usually smaller than the ionizing continuum luminosity of its young stars, the two are comparable in the most massive systems, and the cooling radiation is produced at larger radii, where the Ly-alpha photons are less likely to be extinguished by dust. We suggest, in particular, that cooling radiation could explain the two large (\sim 100 kpc), luminous (L_{Ly-alpha} \sim 10^{44} erg s^{-1}) ``blobs'' of Ly-alpha emission found in Steidel et al.'s (1999) narrow band survey of a z = 3 proto-cluster. Our simulations predict objects of the observed luminosity at about the right space density, and radiative transfer effects can account for the observed sizes and line widths. We discuss observable tests of this hypothesis for the nature of the Ly-alpha blobs, and we present predictions for the contribution of cooling radiation to the Ly-alpha luminosity function of galaxies as a function of redshift.Comment: Submitted to ApJ. 28 pages including 9 PS figures. Version with color figures available at http://donald.astro.umass.edu/~fardal/papers/cooling/cooling.htm

    The Optimal Single Copy Measurement for the Hidden Subgroup Problem

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    The optimization of measurements for the state distinction problem has recently been applied to the theory of quantum algorithms with considerable successes, including efficient new quantum algorithms for the non-abelian hidden subgroup problem. Previous work has identified the optimal single copy measurement for the hidden subgroup problem over abelian groups as well as for the non-abelian problem in the setting where the subgroups are restricted to be all conjugate to each other. Here we describe the optimal single copy measurement for the hidden subgroup problem when all of the subgroups of the group are given with equal a priori probability. The optimal measurement is seen to be a hybrid of the two previously discovered single copy optimal measurements for the hidden subgroup problem.Comment: 8 pages. Error in main proof fixe

    Constraining the Metallicity of the Low Density Lyman-alpha Forest Using OVI Absorption

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    We search for OVI absorption in a Keck HIRES spectrum of the z=3.62 quasar Q1422+231. Comparison of CIV measurements to cosmological simulations shows that \lya forest absorbers with N_HI > 10^{14.5} have [C/H]~=-2.5, for the UV background spectrum of Haardt & Madau (HM). Lower column density absorption arises in lower density gas, where OVI is the most sensitive metal tracer. Since OVI lines lie at wavelengths contaminated by Lyman series absorption, we interpret our Q1422 results by comparing to artificial spectra drawn from an SPH simulation of a Lambda-dominated CDM model. A search for deep, narrow features in Q1422 yields only a few candidate OVI lines, statistically consistent with the number in artificial spectra with no metals; spectra generated with the HM background and [O/H] >= -2.5 predict too many narrow lines. However, applying the optical depth ratio technique of Songaila (1998), we DO find significant OVI associated with CIV systems; matching Q1422 requires [O/C]~=+0.5, implying [O/H]~=-2.0. Taken together these results imply that (a) the metallicity in the low density IGM is at least a factor of three below that in the overdense regions where CIV absorption is detectable, and (b) oxygen is overabundant in these regions, consistent with the enrichment pattern of old halo stars. If the UV background is heavily truncated above 4 Ry, an implausibly high oxygen overabundance ([O/C]>+2) is required by the data; thus a majority of the volume of the universe must have undergone helium reionization by z=3.(Abridged)Comment: Submitted to ApJ, 48 pp including 14 ps figures, uses aaspp4.st

    Evaluation of Power Quality Issues in grid Connected PV Systems

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    This paper deals with the evaluation of power quality issues in grid connected PV systems. This paper also presents  complete simulation, modeling and control of three phase grid connected solar PV module with Maximum Power Point Tracking. Perturb and Observe (P&amp;O) method has been used for Maximum Power Point Tracking. In the proposed model DC bus voltage control , harmonic mitigation and power factor control are discussed as power quality issues. The simulation results are shown in the graphical waveforms and simulation is performed in MATLAB using SIMULINK environment and PSB toolboxes.

    Membrane function alterations in erythrocytes from mood disorder patients

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    Objectives: To examine erythrocyte membrane functions in mood disorder patients and to establish possible diagnostic marker parameter(s).Design: Collection of blood samples from mood disorder patients and age-matched control volunteers.Preparation of erythrocyte membranes for the proposed studies.Setting: Out patients / in patients, psychiatry ward, Civil Hospital, Ahmedabad, Gujarat, India, Department of Biochemistry, Faculty of Science, M.S.University of Baroda, Vadodara, Gujarat, India.Subjects: Unipolar and bipolar subjects. Control subjects (randomly selected volunteers).Results: The most significant results were a duration dependent decrease in the TPL/CHL ratio (mole:mole),changes in both the substrate and temperature kinetics properties of AChE and elevated plasma BChE activity in the mood disorder patients.Conclusion: The results suggest that the altered lipid profiles and the TPL/CHL (mole: mole) ratio and the altered temperature-dependent activity coefficients of erythrocyte membrane AChE and elevated plasma BChE activities could serve as useful diagnostic pointers for mood disorders.Keywords:Membrane function; Erythrocytes; Mood disorderSA Psych Rev 2003;6:11-2
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