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Ethanolamine (NH2CH2CH2OH) has recently been identified in the molecular cloud G+0.693-0.027, situated in the SgrB2 complex in the Galactic center. However, its presence in other regions, and in particular in star-forming sites, is still elusive. Given its likely role as a precursor to simple amino acids, understanding its presence in the star-forming region is required. Here, we present the experimentally obtained temperature-dependent spectral features and morphological behavior of pure ethanolamine ices under astrochemical conditions in the 2 - 12 micro meter (MIR) and 120 - 230 nm (VUV) regions for the first time. These features would help in understanding its photochemical behavior. In addition, we present the first chemical models specifically dedicated to ethanolamine. These models include all the discussed chemical routes from the literature, along with the estimated binding energies and activation energies from quantum chemical calculations reported in this work. We have found that surface reactions: CH2OH + NH2CH2 --> NH2CH2CH2OH and NH2 + C2H4OH --> NH2CH2CH2OH in warmer regions (60-90 K) could play a significant role in the formation of ethanolamine. Our modeled abundance of ethanolamine complements the upper limit of ethanolamine column density estimated in earlier observations in hot core/corino regions. Furthermore, we provide a theoretical estimation of the rotational and distortional constants for various species (such as HNCCO, NH2CHCO, and NH2CH2CO) related to ethanolamine that have not been studied in existing literature. This study could be valuable for identifying these species in the future., Comment: 18 pages, 6 figures. Accepted for the publication in The Astrophysical Journal

Collisional excitation of light hydrides is important to fully understand the complex chemical and physical processes of atmospheric and astrophysical environments. Here, we focus on the NH(X3{\Sigma}-)-Ar van der Waals system. First, we have calculated a new three-dimensional Potential Energy Surface (PES), which explicitly includes the NH bond vibration. We have carried out the ab initio calculations of the PES employing the open-shell single- and double-excitation couple cluster method with noniterative perturbational treatment of the triple excitations. To achieve a better accuracy, we have first obtained the energies using the augmented correlation-consistent aug-cc-pVXZ (X = T, Q, 5) basis sets and then we have extrapolated the final values to the complete basis set limit. We have also studied the collisional excitation of NH(X3{\Sigma}-)-Ar at the close-coupling level, employing our new PES. We calculated collisional excitation cross sections of the fine-structure levels of NH by Ar for energies up to 3000 cm-1 . After thermal average of the cross sections, we have then obtained the rate coefficients for temperatures up to 350 K. The propensity rules between the fine-structure levels are in good agreement with those of similar collisional systems, even though they are not as strong and pronounced as for lighter systems, such as NH-He. The final theoretical values are also compared with the few available experimental data.

The classical view of mass is that it quantifies the amount of substance and is a kinematical parameter. All matter has an attribute of mass and is a conserved quantity in any interaction. With the advent of special relativity, mass became no longer a conserved quantity, since energy and momenta had the status of conserved variables. Nevertheless, the expression for relativistic mass gives a Poincare invariant measure that can be associated as the mass, a useful attribute of the body or system. In the quantum regime, mass becomes truly dynamical. Higgs field is said to provide mass to all the species of elementary constituents - as widely popularized by the media in connection with the recent (most likely) discovery of the Higgs meson at CERN. However, we emphasize that the most abundant component of matter - Nucleons - derives its mass largely as a consequence of quantum effects of (color gluonic QCD) radiation. Further, interestingly this arises out of literally nothing, save the QCD scale determined experimentally, through a self consistent perturbative analysis of nucleon structure., Comment: Published (in Physics Education(www.physedu.in) version,1 figure added

We have studied the OH masers in the star forming region, W3(OH), with data obtained from the Very Long Baseline Array (VLBA). The data provide an angular resolution of $\sim$5 mas, and a velocity resolution of 106 m s$^{-1}$. A novel analysis procedure allows us to differentiate between broadband temporal intensity fluctuations introduced by instrumental gain variations plus interstellar diffractive scintillation, and intrinsic narrowband variations. Based on this 12.5 hours observation, we are sensitive to variations with time scales of minutes to hours. We find statistically significant intrinsic variations with time scales of $\sim$15--20 minutes or slower, based on the {\it velocity-resolved fluctuation spectra}. These variations are seen predominantly towards the line shoulders. The peak of the line profile shows little variation, suggesting that they perhaps exhibit saturated emission. The associated modulation index of the observed fluctuation varies from statistically insignificant values at the line center to about unity away from the line center. Based on light-travel-time considerations, the 20-minute time scale of intrinsic fluctuations translates to a spatial dimension of $\sim$2--3 AU along the sight-lines. On the other hand, the transverse dimension of the sources, estimated from their observed angular sizes of about $\sim$3 mas, is about 6 AU. We argue that these source sizes are intrinsic, and are not affected by interstellar scatter broadening. The implied peak brightness temperature of the 1612/1720 maser sources is about $\sim2\times 10^{13}$ K, and a factor of about five higher for the 1665 line., Comment: Accepted for publication in The Astrophysical Journal

The recently started Arecibo L-band Feed Array (ALFA) pulsar survey aims to find ~1000 new pulsars. Due to its high time and frequency resolution the survey is especially sensitive to millisecond pulsars, which have the potential to test gravitational theories, detect gravitational waves and probe the neutron-star equation of state. Here we report the results of our preliminary analysis: in the first months we have discovered 21 new pulsars. One of these, PSR J1906+0746, is a young 144-ms pulsar in a highly relativistic 3.98-hr low-eccentricity orbit. The 2.61 +- 0.02 solar-mass system is expected to coalesce in ~300 Myr and contributes significantly to the computed cosmic inspiral rate of compact binary systems., Comment: 8 pages, invited review for the Hanas Pulsar Symposium, ChJAA in press

We report here on variable propagation effects in over twenty years of multi-frequency timing analysis of pulsar PSR B1937+21 that determine small-scale properties of the intervening plasma as it drifts through the sight line. The phase structure function derived from the dispersion measure variations is in remarkable agreement with that expected from the Kolmogorov spectrum, with a power law index of $3.66\pm 0.04$, valid over an inferred scale range of 0.2--50 A.U. The observed flux variation time scale and the modulation index, along with their frequency dependence, are discrepant with the values expected from a Kolmogorov spectrum with infinitismally small inner scale cutoff, suggesting a caustic-dominated regime of interstellar optics. This implies an inner scale cutoff to the spectrum of $\sim 1.3\times 10^9$ meters. Our timing solutions indicate a transverse velocity of 9 km sec$^{-1}$ with respect to the solar system barycenter, and 80 km sec$^{-1}$ with respect to the pulsar's LSR. We interpret the frequency dependent variations of DM as a result of the apparent angular broadening of the source, which is a sensitive function of frequency ($\propto\nu^{-2.2}$). The error introduced by this in timing this pulsar is $\sim$2.2 $\mu$s at 1 GHz. The timing error introduced by ``image wandering'' from the slow, nominally refractive scintillation effects is about 125 nanosec at 1 GHz. The error accumulated due to positional error (due to image wandering) in solar system barycentric corrections is about 85 nanosec at 1 GHz., Comment: Accepted for publication in the Astrophysical Journal

This paper discusses the legal basis for the National Library Board's national role for library development in Singapore. It examines the new National Library Board (NLB) Act 1995 and the direct and expanded responsibility it has given the NLB for the national and public library functions in Singapore. The paper also examines the various mechanisms the act provides for NLB to more concretely influence library development in the country as a whole. Highlights include: publicly-funded libraries; national projects; the endowment fund; manpower and training; working in consultation; and school libraries and other major library systems. (MES)

We have carried out a study of the orthogonal polarisation mode behaviour as a function of frequency of 18 pulsars, using average pulsar data from the European Pulsar Network (EPN). Assuming that the radiation consists of two 100% polarised completely orthogonal superposed modes we separated these modes, resulting in average pulse profiles of each mode at multiple frequencies for each pulsar. Furthermore, we studied the frequency dependence of the relative intensity of these modes. We found in many pulsars that the average pulse profiles of the two modes differ in their dependence on frequency. In particular, we found that pulse components that are dominated by one mode tend to increase in intensity with increasing frequency with respect to the rest of the profile., Comment: 31 pages, 24 figures, 1 table, accepted by A&A; added references in introduction

We report the discovery of PSR J1906+0746, a young 144-ms pulsar in a highly relativistic 3.98-hr orbit with an eccentricity of 0.085 and expected gravitational wave coalescence time of 300 Myr. The new pulsar was found during precursor survey observations with the Arecibo 1.4-GHz feed array system and retrospectively detected in the Parkes Multibeam plane pulsar survey data. From radio follow-up observations with Arecibo, Jodrell Bank, Green Bank, and Parkes, we have measured the spin-down and binary parameters of the pulsar and its basic spectral and polarization properties. We also present evidence for pulse profile evolution, which is likely due to geodetic precession, a relativistic effect caused by the misalignment of the pulsar spin and total angular momentum vectors. Our measurements show that PSR J1906+0746 is a young object with a characteristic age of 112 kyr. From the measured rate of orbital periastron advance 7.57+/-0.03 deg/yr, we infer a total system mass of 2.61+/-0.02 Msun. While these parameters suggest that the PSR J1906+0746 binary system might be a younger version of the double pulsar system, intensive searches for radio pulses from the companion have so far been unsuccessful. It is therefore not known whether the companion is another neutron star or a massive white dwarf. Regardless of the nature of the companion, a simple calculation suggests that the Galactic birth rate of binaries similar to PSR J1906+0746 is 60/Myr. This implies that PSR J1906+0746 will make a significant contribution to the computed cosmic inspiral rate of compact binary systems., Comment: 19 pages, 3 figures, accepted for publication in ApJ