Diophantine transference principle over function fields

We study the Diophantine transference principle over function fields. By adapting the approach of Beresnevich and Velani to the function field set-up, we extend many results from homogeneous Diophantine approximation to the realm of inhomogeneous Diophantine approximation over function fields. This also yields the inhomogeneous Baker-Sprindzuk conjecture over function fields as a consequence. Furthermore, we prove the upper bounds for the general non-extremal scenario

Dirichlet improvability for SS-numbers

We study the problem of improving Dirichlet's theorem of metric Diophantine approximation in the $S$-adic setting. Our approach is based on translation of the problem related to Dirichlet improvability into a dynamical one, and the main technique of our proof is the $S$-adic version of quantitative nondivergence estimate due to D. Y. Kleinbock and G. Tomanov. The main result of this paper can be regarded as the number field version of earlier works of D. Y. Kleinbock and B. Weiss, and of the second named author and Anish Ghosh. Also this in turn generalises a result of Shreyasi Datta and M. M. Radhika on singularity of vectors to any number field $K$ and $S$ containing all archimedian places

Effect of ionic strength on the organization and dynamics of membrane-bound melittin

Melittin, a cationic hemolytic peptide, is intrinsically fluorescent due to the presence of a single functionally important tryptophan residue. We have previously shown that the sole tryptophan of melittin is localized in a motionally restricted environment in the membrane interface. We have monitored the effect of ionic strength on the organization and dynamics of membrane-bound melittin utilizing fluorescence and circular dichroism (CD) spectroscopic approaches. Our results show that red edge excitation shift (REES) of melittin bound to membranes is sensitive to the change in ionic strength of the medium. This could be attributed to a change in the immediate environment around melittin tryptophan with increasing ionic strength due to differential solvation of ions. Interestingly, the rotational mobility of melittin does not appear to be affected with change in ionic strength. In addition, fluorescence parameters such as lifetime and acrylamide quenching of melittin indicate an increase in water penetration in the membrane interface upon increasing ionic strength. Our results suggest that the solvent dynamics and water penetration in the interfacial region of the membranes are significantly affected at physiologically relevant ionic strength. These results assume significance in the overall context of the influence of ionic strength in the organization and dynamics of membrane proteins and membrane-active peptides

Unveiling the Dark Side

Discovery and characterisation of black holes (BHs), neutron stars (NSs), and white dwarfs (WDs) with detached luminous companions (LCs) in wide orbits are exciting because they are important test beds for dark remnant (DR) formation physics as well as binary stellar evolution models. Recently, 187 candidates have been identified from Gaia's non-single star catalog as wide orbit (P_orb > 45 days), detached binaries hosting DRs. We identify UV counterparts for 49 of these sources in the archival GALEX data. Modeling the observed spectral energy distribution (SED) spanning FUV-NUV to IR for these sources and stellar evolution models, we constrain the LC properties including mass, bolometric luminosity, and effective temperature for these 49 sources. Using the LC masses, and the astrometric mass function constrained by Gaia, we constrain the DR masses for these sources. We find that 9 have masses clearly in the NS or BH mass range. Fifteen sources exhibit significant NUV excess and 4 show excess both in FUV and NUV. The simplest explanation for these excess UV flux is that the DRs in these sources are white dwarfs (WDs). Using SED modeling we constrain the effective temperature and bolometric luminosity for these 15 sources. Our estimated DR masses for all of these 15 sources are lower than the Chandrasekhar mass limit for WDs. Interestingly, five of these sources had been wrongly identified as neutron stars in literature.Comment: 11 pages, 8 figures, 2 tables, comments welcom

Hunting Down White Dwarf--Main Sequence Binaries Using Multi-Wavelength Observations

Identification of white dwarfs (WD) with main-sequence (MS) companions and characterization of their properties can put important constraints on our understanding of binary stellar evolution and guide the theoretical predictions for a wide range of interesting transient events relevant for, e.g., LSST, ZTF, and LISA. In this study, we combine ultraviolet (UV) and optical color-magnitude diagrams (CMDs) to identify unresolved WD--MS binaries. In particular, we combine high-precision astrometric and photometric data in the optical from \gaia\ -DR3 and UV data from GALEX GR6/7 to identify 111 WD--MS candidates within 100 pc. Of these, 92 are newly identified. Using the Virtual Observatory SED Analyzer (VOSA) we fit the spectral energy distributions (SEDs) of all our candidates and derive stellar parameters, such as effective temperature, bolometric luminosity, and radius for both companions. We find that our identification method helps identify hotter and smaller WD companions (majority with $\geq$10,000 K and $\leq$0.02 $R_\odot$) relative to the WDs identified by past surveys. We infer that these WDs are relatively more massive ($>0.3 M_\odot$). We find that most of the MS companions in our binaries are of the $K$ and $M$ spectral types.Comment: 11 pages, 7 figures, one table, Submitted to MNRAS journa

Offshoring: The Transition From Economic Drivers Toward Strategic Global Partnership and 24-Hour Knowledge Factory

The concept of offshoring of professional services first gained attention slightly over 25 years ago. At that time, US companies began to realize the cost-advantage of getting their computer software developed in India and other countries. The concept gained momentum with the advent of Internet and the availability of inexpensive communication technologies. Unrelated events, such as the need to address the Y2K problem, in a timebound manner, further increased the use of computer personnel based in faraway places. Studies conducted by professional organizations, such as ACM, IEEE, and NSPE, focus on the cost and labor aspects of offshoring and its direct impact on employment opportunities in the countries involved. This paper broadens this perspective by emphasizing that the key drivers for offshoring will be strategic, not economic, over time. A formal mathematical model is presented to highlight the new trend. Further, instead of a binary model in which the work is performed in the country of the sponsoring organization or a different country, we will gradually see a new work paradigm in which the work is performed in a sequence in factories located in multiple continents of the world. Such 24-Hour Knowledge Factories can leverage factors beyond cost savings. One can employ professionals in multiple parts of the world, perform tasks at all times of the day, and bring new products and services quicker to the market. Just as the advent of multiple shifts allowed machines to be utilized round the clock leading to the benefits of the Industrial Revolution, the creation of new globally distributed workforces and global partnerships can lead to major strategic advantages for companies and countries alike