Cycled operation of water vapor electrolysis cell Annual report, 1 Jan. - 31 Dec. 1969

Mathematical model of heat, mass, and momentum relationships in cyclic operation of water vapor electrolytic cell, and equilibrium conditions between gel matrix and vapo

Is the Redshift Clustering of Long-Duration Gamma-Ray Bursts Significant?

The 26 long-duration gamma-ray bursts (GRBs) with known redshifts form a distinct cosmological set, selected differently than other cosmological probes such as quasars and galaxies. Since the progenitors are now believed to be connected with active star-formation and since burst emission penetrates dust, one hope is that with a uniformly-selected sample, the large-scale redshift distribution of GRBs can help constrain the star-formation history of the Universe. However, we show that strong observational biases in ground-based redshift discovery hamper a clean determination of the large-scale GRB rate and hence the connection of GRBs to the star formation history. We then focus on the properties of the small-scale (clustering) distribution of GRB redshifts. When corrected for heliocentric motion relative to the local Hubble flow, the observed redshifts appear to show a propensity for clustering: 8 of 26 GRBs occurred within a recession velocity difference of 1000 km/s of another GRB. That is, 4 pairs of GRBs occurred within 30 h_65^-1 Myr in cosmic time, despite being causally separated on the sky. We investigate the significance of this clustering. Comparison of the numbers of close redshift pairs expected from the simulation with that observed shows no significant small-scale clustering excess in the present sample; however, the four close pairs occur only in about twenty percent of the simulated datasets (the precise significance of the clustering is dependent upon the modeled biases). We conclude with some impetuses and suggestions for future precise GRB redshift measurements.Comment: Published in the Astronomical Journal, June 2003: see http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2003AJ....125.2865

The impact of health on professionally active people's incomes in Poland. Microeconometric analysis

The outcome of the research confirms the occurrence of positive interaction between professionally active people's incomes and the self-assessed state of health. People declaring a bad state of health have incomes by 20% on average lower than people who enjoy good health (assuming that the remaining characteristics of the surveyed person are the same). In case of men, the impact of health state on incomes is slightly greater than in case of women.Wyniki badań potwierdzają istnienie pozytywnej zależności dochodów osób aktywnych zawodowo od stanu zdrowia mierzonego jego samooceną. Osoby deklarujące zły stan zdrowia osiągają dochody przeciętnie o 20% niższe niż osoby, które cieszą się dobrym stanem zdrowia (przy założeniu, że pozostałe charakterystyki badanej osoby są takie same). W przypadku mężczyzn zależność dochodów od stanu zdrowia jest nieznacznie silniejsza niż w przypadku kobiet

The Discovery of Vibrationally-Excited H_2 in the Molecular Cloud near GRB 080607

GRB 080607 has provided the first strong observational signatures of molecular absorption bands toward any galaxy hosting a gamma-ray burst. Despite the identification of dozens of features as belonging to various atomic and molecular (H_2 and CO) carriers, many more absorption features remained unidentified. Here we report on a search among these features for absorption from vibrationally-excited H_2, a species that was predicted to be produced by the UV flash of a GRB impinging on a molecular cloud. Following a detailed comparison between our spectroscopy and static, as well as dynamic, models of H_2* absorption, we conclude that a column density of 10^{17.5+-0.2} cm^{-2} of H_2* was produced along the line of sight toward GRB 080607. Depending on the assumed amount of dust extinction between the molecular cloud and the GRB, the model distance between the two is found to be in the range 230--940 pc. Such a range is consistent with a conservative lower limit of 100 pc estimated from the presence of Mg I in the same data. These distances show that substantial molecular material is found within hundreds of pc from GRB 080607, part of the distribution of clouds within the GRB host galaxy.Comment: Submitted to ApJL, 6 pages emulate

The star-formation rate in the host of GRB 990712

We have observed the host galaxy of GRB 990712 at 1.4 GHz with the Australia Telescope Compact Array, to obtain an estimate of its total star-formation rate. We do not detect a source at the position of the host. The 2 sigma upper limit of 70 microJy implies that the total star-formation rate is lower than 100 Msun/yr, using conservative values for the spectral index and cosmological parameters. This upper limit is in stark contrast with recent reports of radio/submillimeter-determined star-formation rates of roughly 500 Msun/yr for two other GRB host galaxies. Our observations present the deepest radio-determined star-formation rate limit on a GRB host galaxy yet, and show that also from the unobscured radio point-of-view, not every GRB host galaxy is a vigorous starburst.Comment: A&A Letters, in press, 5 pages; a high-resolution color gif version of the paper figure is also supplie

Probing the distance and morphology of the Large Magellanic Cloud with RR Lyrae stars

We present a Bayesian analysis of the distances to 15,040 Large Magellanic Cloud (LMC) RR Lyrae stars using $V$- and $I$-band light curves from the Optical Gravitational Lensing Experiment, in combination with new $z$-band observations from the Dark Energy Camera. Our median individual RR Lyrae distance statistical error is 1.89 kpc (fractional distance error of 3.76 per cent). We present three-dimensional contour plots of the number density of LMC RR Lyrae stars and measure a distance to the core LMC RR Lyrae centre of ${50.2482\pm0.0546 {\rm(statistical)} \pm0.4628 {\rm(systematic)} {\rm kpc}}$, equivalently ${\mu_{\rm LMC}=18.5056\pm0.0024 {\rm(statistical)} \pm0.02 {\rm(systematic)}}$. This finding is statistically consistent with and four times more precise than the canonical value determined by a recent meta-analysis of 233 separate LMC distance determinations. We also measure a maximum tilt angle of $11.84^{\circ}\pm0.80^{\circ}$ at a position angle of $62^\circ$, and report highly precise constraints on the $V$, $I$, and $z$ RR Lyrae period--magnitude relations. The full dataset of observed mean-flux magnitudes, derived colour excess ${E(V-I)}$ values, and fitted distances for the 15,040 RR Lyrae stars produced through this work is made available through the publication's associated online data.Comment: 7 pages, 8 figure

The Rapidly Fading Afterglow from the Gamma-Ray Burst of 1999 May 6

We report on the discovery of the radio afterglow from the gamma-ray burst (GRB) of 1999 May 6 (GRB 990506) using the Very Large Array (VLA). The radio afterglow was detected at early times (1.5 days), but began to fade rapidly sometime between 1 and 5 days after the burst. If we attribute the radio emission to the forward shock from an expanding fireball, then this rapid onset of the decay in the radio predicts that the corresponding optical transient began to decay between 1 and 5 minutes after the burst. This could explain why no optical transient for GRB 990506 was detected in spite of numerous searches. The cause of the unusually rapid onset of the decay for the afterglow is probably the result of an isotropically energetic fireball expanding into a low density circumburst environment. At the location of the radio afterglow we find a faint (R ~ 24 mag) host galaxy with a double morphology.Comment: in press at ApJ Letters, 13 page LaTeX document includes 2 postscript figure