7,833 research outputs found

    Constraining the Variation in Fine-Structure Constant Using SDSS DR8 QSO Spectra

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    We report a robust constrain on the possible variation of fine-structure constant, alpha = e^2/(hbar*c), obtained using O III 4959,5007, nebular emission lines from QSOs. We find Delta-alpha/alpha=-(2.1 +/- 1.6) x 10^(-5) based on a well selected sample of 2347 QSOs from Sloan Digital Sky Survey Data Release 8 with 0.02 < z < 0.74. Our result is consistent with a non-varying alpha at a level of 2 x 10^(-5) over approximately 7 Gyr. This is the largest sample of extragalactic objects yet used to constrain the variation of alpha. While this constraint is not as stringent as those determined using many-multiplet method it is free from various systematic effects. A factor of ~ 4 improvement in Delta-alpha/alpha achieved here compared to the previous study (Bahcall et al. 2004) is just consistent with what is expected based on a factor of 14 times bigger sample used here. This suggests that errors are mainly dominated by the statistical uncertainty. We also find the ratio of transition probabilities corresponding to the O III 5007 A and 4959 A lines to be 2.933+/-0.002, in good agreement with the National Institute of Standards and Technology measurements.Comment: 5 pages, 3 figures; Accepted for publication in MNRAS Lette

    Removal of benzotriazole by Photo-Fenton like process using nano zero-valent iron: Response surface methodology with a Box-Behnken design

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    In this paper, the removal of benzotriazole (BTA) was investigated by a Photo-Fenton process using nano zero valent iron (NZVI) and optimization by response surface methodology based on Box-Behnken method. Effect of operating parameters affecting removal efficiency such as H2O2, NZVI, and BTA concentrations as well as pH was studied. All the experiments were performed in the presence of ultraviolet radiation. Predicted levels and BTA removal were found to be in good agreement with the experimental levels (R2 = 0. 9500). The optimal parameters were determined at 60 min reaction time, 15 mg L-1 BTA, 0.10 g L-1 NZVI, and 1.5 mmol L-1 H2O2 for Photo-Fenton-like reaction. NZVI was characterized using X-ray diffraction (XRD), transmission electron microscope (TEM) images, and scanning electron microscope (SEM) analysis

    Sharp Response Microstrip LPF using Folded Stepped Impedance Open Stubs

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    A novel microstrip lowpass filter with high selectivity and wide stopband is proposed that comprises two lateral folded open stubs and a central mirrored semi-circle ended suppressing cell. The proposed filter has cut-off frequency of 2.28 GHz and is very compact. The stopband width with attenuation level more than -20 dB is equal to 5.47 fc and the transition band is only 0.14 GHz. This filter is designed, fabricated and measured and the simulated and measured results are in good agreemen

    Parsec-scale structures and diffuse bands in a translucent interstellar medium at z 0.079

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    We present a detailed study of the QSO-galaxy pair [SDSS J163956.35+112758.7 (zq = 0.993) and SDSS J163956.38+112802.1 (zg = 0.079)] based on observations carried out using the Giant Meterwave Radio Telescope (GMRT), the Very Large Baseline Array (VLBA), the Sloan Digital Sky Survey (SDSS) and the ESO New Technology Telescope (NTT). We show that the interstellar medium of the galaxy probed by the QSO line of sight has near-solar metallicity (12+log(O/H) = 8.47+/-0.25) and dust extinction (E(B-V) 0.83+/-0.11) typical of what is usually seen in translucent clouds. We report the detection of absorption in the \lambda 6284 diffuse interstellar band (DIB) with a rest equivalent width of 1.45+/-0.20\AA. Our GMRT spectrum shows a strong 21-cm absorption at the redshift of the galaxy with an integrated optical depth of 15.70+/-0.13 km/s. Follow-up VLBA observations show that the background radio source is resolved into three components with a maximum projected separation of 89 pc at the redshift of the galaxy. One of these components is too weak to provide useful HI 21-cm absorption information. The integrated HI optical depth towards the other two components are higher than that measured in our GMRT spectrum and differ by a factor 2. By comparing the GMRT and VLBA spectra we show the presence of structures in the 21-cm optical depth on parsec scales. We discuss the implications of such structures for the spin-temperature measurements in high-z damped Lyman-alpha systems. The analysis presented here suggests that this QSO-galaxy pair is an ideal target for studying the DIBs and molecular species using future observations in optical and radio wavebands.Comment: 10 pages, 8 figures, 2 tables, accepted for publication in MNRA

    Thermally isolated Luttinger liquids with noisy Hamiltonians

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    We study the dynamics of a quantum-coherent thermally isolated Luttinger liquid with noisy Luttinger parameter. To characterize the fluctuations of the absorbed energy in generic noise-driven systems, we first identify two types of energy moments, which can help tease apart the effects of classical (sample-to-sample) and quantum sources of fluctuations. One type of moment captures the total fluctuations due to both sources, while the other one captures the effect of the classical source only. We then demonstrate that in the Luttinger liquid case, the two types of moments agree in the thermodynamic limit, indicating that the classical source dominates. In contrast to equilibrium thermodynamics, in this driven system the relative fluctuations of energy do not decay with the system size. Additionally, we study the deviations of equal-time correlation functions from their ground-state value, and find a simple scaling behavior.Comment: 11 pages, 2 figure

    Junctions of multiple quantum wires with different Luttinger parameters

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    Within the framework of boundary conformal field theory, we evaluate the conductance of stable fixed points of junctions of two and three quantum wires with different Luttinger parameters. For two wires, the physical properties are governed by a single effective Luttinger parameters for each of the charge and spin sectors. We present numerical density-matrix-renormalization-group calculations of the conductance of a junction of two chains of interacting spinless fermions with different interaction strengths, obtained using a recently developed method [Phys. Rev. Lett. 105, 226803 (2010)]. The numerical results show very good agreement with the analytical predictions. For three spinless wires, i.e., a Y junction, we analytically determine the full phase diagram, and compute all fixed-point conductances as a function of the three Luttinger parameters.Comment: 13 pages, 6 figure

    Comparison of copper concentrations in liver and muscle of Squalius cephalus and Capoeta capoeta gracilis (Pisces: Teleostei) in Tajan River, Iran

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    The aim of this study was to determine and compare the concentration of copper (Cu) in liver and muscle of two fish species Squalius cephalus and Capoeta capoeta gracilis. The fish were caught in four sampling sites along Tajan River, Mazandaran Province, northern Iran. The concentration of Cu was determined using flame atomic absorption spectrometry. There were significant differences (P<0.05) between the sampling sites with regard to Cu concentration in both muscle and liver of fish species.Significant differences were also found (P<0.05) between S. cephalus and C. c. gracilis regarding Cu content in liver and muscle tissues. The content of Cu in the liver was greater (P<0.05) than that in the muscle in both species. Also, Cu content of liver in both species was higher than the standard limits declared by WHO. This study reports high loads of Cu in Tajan River and a high content of Cu in the muscle and liver of S. cephalus and C. c. gracilis

    Effect of the nursing process using via "accessible care cards" on the patients' satisfaction of nursing care in intensive care units of Golestan Hospital, Ahvaz

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    Background and aims: Nursing process is performance Standard for nursing cares. According to their conditions and facilities, various centers can choose and implement a nursing process that is more efficient for them. This study was aimed to determine the effect of nursing process the way "accessible care cards" on patients' satisfaction from care in intensive care units. Methods: This is a cross-sectional interventional study with plan case-control study that was conducted in Golestan hospital in Ahwaz in 2014. Considering the inclusion criteria and available sampling method, a total of 38 controls and 38 cases were selected for the intervention group were evaluated. Data were collected questionnaire made by researcher, which was assess the scientific validity, the content validity method were used validated. As well as its reliability using Cronbach's alpha test (α= 0.9) was determined. Intervention was conducted by accessible care cards in nursing process for two weeks and its impact on patient satisfaction was measured. The control group was routine care. The collected data was analyzed by SPSS 19 and statistical tests. Descriptive statistics such as mean, and standard deviation was used. Chi-square test, Mann-whitney and t-test were used to compare groups. Results: Results showed that 28.90% of patients in the control group had great satisfaction of care, while the 97.36% of patients in the intervention group reported nearly excellent satisfaction. The observed difference in patients' satisfaction with nursing care in both the experimental and control group was statistically significant (P<0.001). Conclusion: Implementation of nursing process, in a manner of available cards led to an increase in patient satisfaction compared with the routine manner and the use of these cards makes the nursing process of a greater degree of mental state, to objectively state, that can help in saving a lot of time for nurses
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