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

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

Spanning trees for the geometry and dynamics of compact polymers

Using a mapping of compact polymers on the Manhattan lattice to spanning trees, we calculate exactly the average number of bends at infinite temperature. We then find, in a high temperature approximation, the energy of the system as a function of bending rigidity and polymer elasticity. We identify the universal mechanism for the relaxation of compact polymers and then endow the model with physically motivated dynamics in the convenient framework of the trees. We find aging and domain coarsening after quenches in temperature. We explain the slow dynamics in terms of the geometrical interconnections between the energy and the dynamics.Comment: 10 pages, 8 figure

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

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

Effects of salinity on potassium absorption and expression of K+transporter genes at different concentrations of potassium in Grape (Vitis vinifera L.)

Grapevine is classified as a moderately sensitive plant to salinity. Hydroponically three grape genotypes (Vitis vinifera L.) were treated with different concentrations of KCl (0.1, 0.3, 0.5, 1, 5, 10 mM KCl) and NaCl (0, 25, 50,100 mM NaCl). Cl- and Na+ contents were significantly increased in different plant organs of all the genotypes under salinity. In this study, sensitive ('GhezelUzum'), tolerant ('Gharashani') and semi-resistant ('Chawga') grape genotypes were selected based on screening experiments under salinity. 'Gharashani' accumulated higher Na+ and Cl- in roots compared to the sensitive one. 'Chawga' accumulated high K+ similar to Na+ in root and shoot even at high salinity. Km calculation for K+ and Na+ uptake in root and shoot of 'Chawga' showed that K+ and Na+ compete to enter the plant through roots. Two KUP/KT/HAK-type potassium transporters are expressed highly in the grapevine during stress. VvK1.1 could play a major role in K+ loading into grape tissues. The expression of VvKUP1 and VvKUP2 transporters and VvK1.1 channel in roots of 'Chawga' genotype increased significantly (P &lt; 0.05) at different KCl concentrations under salinity stress. Our results showed a significant difference between tolerant and sensitive genotypes and highlighted a strong relationship between the accumulation of specific transcripts and the degree of salinity tolerance

Floating Car and Camera Data Fusion for Non-parametric Route Travel Time Estimation

AbstractTraffic management centers take advantage of various data collection systems ranging from stationary sensors e.g. automated vehicle identification systems to mobile sensors e.g. fleet management systems. Each type of data collection system has its own advantages and disadvantages. Stationary sensors has less measurement noise than mobile sensors but their network coverage is limited. On the other hand, mobile sensors cover expand areas of road networks but they have less penetration rate and frequency of reports. Traffic state estimation can benefit from fusion of data from various sources as they complement each other. This paper introduces a route travel time estimation method that aggregates data from two traffic data sources, automated number plate recognition system and floating car data

SUBJECTIVE WELL BEING SEBAGAI PREDIKTOR ONLINE DISINHIBITION EFFECT PADA MAHASISWA

Pandemi COVID-19 memaksa orang untuk lebih banyak melakukan aktivitasnya secara daring. Online disinhibition effect (ODE) adalah menurunnya hambatan psikologis selama interaksi dengan orang lain dalam lingkungan sosial secara daring. ODE memiliki dua dimensi, yaitu benign dan toxic online disinhibition. Salah satu faktor yang memengaruhi ODE adalah subjective wellbeing (SWB). Penelitian ini bertujuan untuk meneliti sejauh mana SWB dapat memprediksi ODE. Sebanyak 227 mahasiswa menjadi sasaran responden penelitian ini. Rancangan penelitian menggunakan desain korelasional. Alat ukur yang dipergunakan untuk mengukur SWB adalah Satisfaction with Life Scale and Scale of Positive and Negative Experience (SPANE), dan untuk mengukur ODE adalah online disinhibition scale (ODS). Teknik analisis statistik yang digunakan adalah regresi sederhana untuk menghitung besarnya kontribusi SWB terhadap ODE. Hasil penelitian menunjukkan bahwa tiap komponen SWB tidak berkontribusi signifikan terhadap benign maupun toxic online disinhibition. Simpulan penelitian ini adalah SWB bukan merupakan prediktor langsung terhadap ODE. Saran untuk penelitian selanjutnya adalah meneliti mediator yang mungkin memengaruhi ODE, seperti regulasi emosi, trait kepribadian dan tingkat keparahan kondisi pandemi

Development of Digital Hysteresis Current Control with PLL Loop Gain Compensation Strategy for PWM Inverters with Constant Switching Frequency

Hysteresis current control is one of the simplest techniques used to control the magnitude and phase angle of motor current for motor drives systems. However, this technique presents several disadvantages such as operation at variable switching frequency which can reveal problems of filtering, interference between the phases in the case of the three-phase systems with insulated neutral connection or delta connection, and irregularity of the modulation pulses which especially causes an acoustic noise on the level of the machine for the high power drive. In this paper, a new technique is proposed for a variable-hysteresis-band controller based on dead beat control applied to three phase voltage source PWM inverters feeding AC motors. Its main aim is firstly ensure a constant switching frequency and secondly the synchronization of modulation pulses using the phase-locked-loop with loop gain compensation in order to ensure a better stability. The behavior of the proposed technique is verified by simulation

Combined analytical and experimental evaluation of frictional performance of lubricated untextured and partially textured sliders

The study of textured surface performance is one of the highly researched topics in recent times. This is mainly due to the advantages that such surfaces can potentially provide in practice, in mitigating adverse tribological conditions, such as friction and wear. However, considering the complexities found in practice, a methodological analysis and evaluation procedure is essential in order to gain an understanding of the benefits from utilising such features in a given contact. The current study provides a combined analytical and experimental approach towards an enhanced understanding of the behaviour of textured surfaces relative to their untextured counterparts. The developed analytical models are invaluable in providing an insight into the relationship between the many parameters involved in defining even simple surface texture feature geometry and the expected outcomes in practice, when corroborated with experimental results. The current study reports on such an endeavour. With the studied texture configuration, the results have shown the possibility of reducing friction by as much as 25%