Comment on "Limits on the Time Variation of the Electromagnetic Fine-Structure Constant in the Low Energy Limit from Absorption Lines in the Spectra of Distant Quasars"

In their Letter [Phys. Rev. Lett. 92, 121302 (2004)] (also [Astron. Astrophys. 417, 853 (2004)]), Srianand et al. analysed optical spectra of heavy-element species in 23 absorption systems along background quasar sight-lines, reporting limits on relative variations in the fine-structure constant: da/a=(-0.06+/-0.06) x 10^{-5}. Here we demonstrate basic flaws in their analysis, using the same data and absorption profile fits, which led to spurious values of da/a and significantly underestimated uncertainties. We conclude that these data and fits offer no stringent test of previous evidence for a varying alpha. In their Reply (arXiv:0711.1742) to this Comment, Srianand et al. state or argue several points regarding their original analysis and our new analysis. We discuss these points here, dismissing all of them because they are demonstrably incorrect or because they rely on a flawed application of simple statistical arguments.Comment: 1+2 pages, 1 EPS figure. Page 1 accepted as PRL Comment on arXiv:astro-ph/0402177 . Further details available in arXiv:astro-ph/0612407 . v2: Added critical discussion of Reply from Srianand et al. (arXiv:0711.1742

Strong Limit on a Variable Proton-to-Electron Mass Ratio from Molecules in the Distant Universe

The Standard Model of particle physics assumes that the so-called fundamental constants are universal and unchanging. Absorption lines arising in molecular clouds along quasar sightlines offer a precise test for variations in the proton-to-electron mass ratio, mu, over cosmological time and distance scales. The inversion transitions of ammonia are particularly sensitive to mu compared to molecular rotational transitions. Comparing the available ammonia spectra observed towards the quasar B0218+357 with new, high-quality rotational spectra, we present the first detailed measurement of mu with this technique, limiting relative deviations from the laboratory value to |dmu/mu| < 1.8x10^{-6} (95% confidence level) at approximately half the Universe's current age - the strongest astrophysical constraint to date. Higher-quality ammonia observations will reduce both the statistical and systematic uncertainties in these measurements.Comment: Science, 20th June 2008. 22 pages, 5 figures (12 EPS files), 2 tables, including Supporting Online Material; v2: Corrected reference for laboratory mu-variation bound

Comparison of serum immunoglobulin G half-life in dairy calves fed colostrum, colostrum replacer or administered with intravenous bovine plasma.

In calves, passive immunity of immunoglobulins can be acquired through ingestion of colostrum or colostrum replacers. Plasma can been used to supplement immunoglobulins in healthy or sick calves. Serum half-life of colostral derived immuglobulin G (IgG) is estimated to be 20 days. Half-life of IgG is important in determining response to antigens and timing of vaccination in calves. To date studies evaluating half-life of colostrum replacer or plasma derived IgG are lacking. The objectives of this study were to compare the serum half-life of IgG derived from colostrum, colostrum replacer and plasma in dairy calves reared up to 35 days of age. Thirty Jersey calves were randomly assigned to receive colostrum or colostrum replacer by oroesophageal tubing or plasma by intravenous administration. Serum samples were collected at 2, 5, 7, 10, 14, 21, 28 and 35 days. Serum IgG concentrations were determined by radial immunodiffusion. The results indicated that half-life for IgG in colostrum fed (28.5 days) or plasma transfused calves (27.3 days) was longer than colostrum replacer fed calves (19.1 days). Further studies are required to evaluate pathogen specific immunoglobulins in order to recommend vaccination timing in calves fed colostrum replacers

Time evolution of the fine structure constant

We present a short review of the current quasar (QSO) absorption line constraints on possible variation of the fine structure constant, alpha = e^2/(hbar*c). Particular attention is paid to recent optical Keck/HIRES spectra of 49 absorption systems which indicate a smaller alpha in the past (Murphy et al. 2001, Webb et al. 2001). Here we present new preliminary results from 128 absorption systems: da/a = (-0.57 +/- 0.10) x 10^{-5} over the redshift range 0.2 < z < 3.7, in agreement with the previous results. Known potential systematic errors cannot explain these results. We compare them with strong `local' constraints and discuss other (radio and millimetre-wave) QSO absorption line constraints on variations in alpha^2 * g_p and alpha^2 * g_p * m_e/m_p (g_p is the proton g-factor and m_e/m_p is the electron/proton mass ratio). Finally, we discuss future efforts to rule out or confirm the current 5.7 sigma optical detection.Comment: Invited review at the XXII Physics in Collision Conference (PIC02), Stanford, CA, USA, June 2002, 11 pages, LaTeX, 7 eps figures. PSN FRA T0

Big bang nucleosynthesis as a probe of fundamental "constants"

Big Bang nucleosynthesis (BBN) is the earliest sensitive probe of the values of many fundamental particle physics parameters. We have found the leading linear dependences of primordial abundances on all relevant parameters of the standard BBN code, including binding energies and nuclear reaction rates. This enables us to set limits on possible variations of fundamental parameters. We find that 7Li is expected to be significantly more sensitive than other species to many fundamental parameters, a result which also holds for variations of coupling strengths in grand unified (GUT) models. Our work also indicates which areas of nuclear theory need further development if the values of ``constants'' are to be more accurately probed.Comment: Refereed article to be published in Nuclear Physics in Astrophysics III Proceedings, J. Phys. G. Special Issue. Based on work in collaboration with C. Wetterich (Heidelberg). 6 page

High-resolution saturation spectroscopy of singly-ionized iron with a pulsed uv laser

We describe the design and realization of a scheme for uv laser spectroscopy of singly-ionized iron (Fe II) with very high resolution. A buffer-gas cooled laser ablation source is used to provide a plasma close to room temperature with a high density of Fe II. We combine this with a scheme for pulsed-laser saturation spectroscopy to yield sub-Doppler resolution. In a demonstration experiment, we have examined an Fe II transition near 260 nm, attaining a linewidth of about 250 MHz. The method is well-suited to measuring transition frequencies and hyperfine structure. It could also be used to measure small isotope shifts in isotope-enriched samples.Comment: 9 pages, 5 figures, updated Fig. 3. For submission to J. Phys.

Hydrocarbons in the banana leaf, Musa sapientum

Mass spectrometry, spectroscopy, and thin layer and gas chromatography studies of hydrocarbons in banana leave