The Detection of Cold Dust in Cas A: Evidence for the Formation of Metallic Needles in the Ejecta

Recently, Dunne et al. (2003) obtained 450 and 850 micron SCUBA images of CasA, and reported the detection of 2-4 M_sun of cold, 18K, dust in the remnant. Here we show that their interpretation of the observations faces serious difficulties. Their inferred dust mass is larger than the mass of refractory material in the ejecta of a 10 to 30 M_sun star. The cold dust model faces even more difficulties if the 170 micron observations of the remnant are included in the analysis, decreasing the cold dust temperature to ~ 8K, and increasing its mass to > 20 M_sun. We offer here a more plausible interpretation of their observation, in which the cold dust emission is generated by conducting needles with properties that are completely determined by the combined submillimeter and X-ray observations of the remnant. The needles consist of metallic whiskers with <1% of embedded impurities that may have condensed out of blobs of material that were expelled at high velocities from the inner metal-rich layers of the star in an asymmetric explosion. The needles are collisionally heated by the shocked gas to a temperature of 8K. Taking the destruction of needles into account, a dust mass of only 1E-4 to 1E-3M_sun is needed to account for the observed SCUBA emission. Aligned in the magnetic field, needles may give rise to observable polarized emission. The detection of submillimeter polarization will therefore offer definitive proof for a needle origin for the cold dust emission. Supernovae may still be proven to be important sources of interstellar dust, but the evidence is still inconclusive.Comment: 18 pages including 4 figures. Accepted for publication in the ApJ. Missing reference adde

Detection of microorganisms at high altitudes

This article does not have an abstract

On the formation of graphite grains in cool stars

Graphite grain formation in cool stars examined on basis of molecular equilibrium data for stellar atmosphere

Structure-based stabilization of insulin as a therapeutic protein assembly via enhanced aromatic-aromatic interactions

Key contributions to protein structure and stability are provided by weakly polar interactions, which arise from asymmetric electronic distributions within amino acids and peptide bonds. Of particular interest are aromatic side chains whose directional π-systems commonly stabilize protein interiors and interfaces. Here, we consider aromatic-aromatic interactions within a model protein assembly: the dimer interface of insulin. Semi-classical simulations of aromatic-aromatic interactions at this interface suggested that substitution of residue TyrB26 by Trp would preserve native structure while enhancing dimerization (and hence hexamer stability). The crystal structure of a [TrpB26]insulin analog (determined as a T3Rf3 zinc hexamer at a resolution of 2.25 Å) was observed to be essentially identical to that of WT insulin. Remarkably and yet in general accordance with theoretical expectations, spectroscopic studies demonstrated a 150-fold increase in the in vitro lifetime of the variant hexamer, a critical pharmacokinetic parameter influencing design of long-acting formulations. Functional studies in diabetic rats indeed revealed prolonged action following subcutaneous injection. The potency of the TrpB26-modified analog was equal to or greater than an unmodified control. Thus, exploiting a general quantum-chemical feature of protein structure and stability, our results exemplify a mechanism-based approach to the optimization of a therapeutic protein assembly

Progress towards the vindication of panspermia

Theories of panspermia are rapidly coming into vogue, with the possibility of the transfer of viable bacterial cells from one planetary abode to another being generally accepted as inevitable. The panspermia models of Hoyle and Wickramasinghe require the transfer of viable bacterial cells from interstellar dust to comets and back into interplanetary and interstellar space. In such a cycle a viable fraction of as little as 10−18 at the inception of a newly formed comet/planet system suffices for cometary panspermia to dominate over competing processes for the origin and transfer of life. The well-attested survival attributes of microbes under extreme conditions, which have recently been discovered, gives credence to the panspermia hypothesis. The prediction of the theory that comets bring microbes onto the Earth at the present time is testable if aseptic collections of stratospheric air above the tropopause can be obtained. We describe a recent collection of this kind and report microbiological analysis that shows the existence of viable cells at 41 km, falling to Earth at the rate of a few tonnes per day over the entire globe. Some of these cells have been cultured in the laboratory and found to include microorganisms that are not too different from related species on the Earth. This is in fact what the Hoyle-Wickramasinghe theory predicts. The weight of evidence goes against the more conservative explanation that organisms are being lofted to the high atmosphere from the ground

Status of heavy metal pollution in the Lunawa lagoon

Distribution offive types of heavy metals in the Lunawa Lagoon (Colombo District) was investigatedfrom April to June 2006. Water and bottom sludge samples were obtained at fortnight intervals fromnine sampling stations of the lagoon including three drains (Northern, Eastern and Uyana). Watersamples were preserved by adding Cone. HNOJ (Analytical Grade) to adjust the pH to &lt; 2 andbottom sludge samples were treated by 'Wet Ashing Method' before analysis. Concentrations of Cu, Zn, Pb, Cd and Cr were determined by Atomic Absorption Spectrophotometry. Cu, Zn, Pb and Crwere found both in water and bottom sludge samples of all sites, while Cd was not recorded from anyof the sites. Significantly higher concentrations of heavy metals (Mean ± SEM: Cu 120.75 ug/g ±8.43; Zn 570.98 ug/g ± 11.53; Pb 204.37 flg/g ± 7.50; Cr 52.50 ug/g ± 4.36: One- way ANOYA;P&lt;O.OI) were found in bottom sludge of the Southern lagoon than the Northern lagoon and the threedrains. This is possible because the Southern lagoon is situated away from the sea outfall and theintensity offlushing by sea water is relatively less in this sector. Heavy metal concentrations in waterin different sites did not differ significantly, however, water in the Southern lagoon contained a relativelyhigher concentrations ofCu (0.049 ppm ± 0.002) and Pb (0.096 ppm ± 0.006) while the highest levelof Cr (0.035 ppm ± 0.020) and Zn (0.151 ppm ± 0.017) were recorded from the Eastern Drain.Bottom sludge contained significantly higher concentrations of all heavy metals than in water (P&lt;O.OOI)indicating accumulation of metal ions in the sludge for a long period of time. Lagoon water could havebeen contaminated by point sources (such as Automotive Workshops and Textile Factories) and nonpointsources (such as Service Stations along the Galle Road) of heavy metal pollutants

Flexible temperature sensor integration into e-textiles using different industrial yarn fabrication processes

Textiles enhanced with thin-film flexible sensors are well-suited for unobtrusive monitoring of skin parameters due to the sensors’ high conformability. These sensors can be damaged if they are attached to the surface of the textile, also affecting the textiles’ aesthetics and feel. We investigate the effect of embedding flexible temperature sensors within textile yarns, which adds a layer of protection to the sensor. Industrial yarn manufacturing techniques including knit braiding, braiding, and double covering were utilised to identify an appropriate incorporation technique. The thermal time constants recorded by all three sensing yarns was <10 s. Simultaneously, effective sensitivity only decreased by a maximum of 14% compared to the uncovered sensor. This is due to the sensor being positioned within the yarn instead of being in direct contact with the measured surface. These sensor yarns were not affected by bending and produced repeatable measurements. The double covering method was observed to have the least impact on the sensors’ performance due to the yarn’s smaller dimensions. Finally, a sensing yarn was incorporated in an armband and used to measure changes in skin temperature. The demonstrated textile integration techniques for flexible sensors using industrial yarn manufacturing processes enable large-scale smart textile fabrication

Observations of radio pulses from CU Virginis

The magnetic chemically peculiar star CU Virginis is a unique astrophysical laboratory for stellar magnetospheres and coherent emission processes. It is the only known main sequence star to emit a radio pulse every rotation period. Here we report on new observations of the CU Virginis pulse profile in the 13 and 20\,cm radio bands. The profile is known to be characterised by two peaks of 100$\%$ circularly polarised emission that are thought to arise in an electron-cyclotron maser mechanism. We find that the trailing peak is stable at both 13 and 20\,cm, whereas the leading peak is intermittent at 13\,cm. Our measured pulse arrival times confirm the discrepancy previously reported between the putative stellar rotation rates measured with optical data and with radio observations. We suggest that this period discrepancy might be caused by an unknown companion or by instabilities in the emission region. Regular long-term pulse timing and simultaneous multi-wavelength observations are essential to clarify the behaviour of this emerging class of transient radio source.Comment: Accepted by MNRAS Letters; 5 pages, 2 figures, 3 table

Modeling Repulsive Gravity with Creation

There is a growing interest in the cosmologists for theories with negative energy scalar fields and creation, in order to model a repulsive gravity. The classical steady state cosmology proposed by Bondi, Gold and Hoyle in 1948, was the first such theory which used a negative kinetic energy creation field to invoke creation of matter. We emphasize that creation plays very crucial role in cosmology and provides a natural explanation to the various explosive phenomena occurring in local (z<0.1) and extra galactic universe. We exemplify this point of view by considering the resurrected version of this theory - the quasi-steady state theory, which tries to relate creation events directly to the large scale dynamics of the universe and supplies more natural explanations of the observed phenomena. Although the theory predicts a decelerating universe at the present era, it explains successfully the recent SNe Ia observations (which require an accelerating universe in the standard cosmology), as we show in this paper by performing a Bayesian analysis of the data.Comment: The paper uses an old SNeIa dataset. With the new improved data, for example the updated gold sample (Riess et al, astro-ph/0611572), the fit improves considerably (\chi^2/DoF=197/180 and a probability of goodness-of-fit=18%

Preliminary observations on the anopheline mosquitoes of gomadiyagala a village in the north western province of Sri Lanka

Investigations on anopheline mosquitoes were carried out in Gomadiyagaladuring January-December 1989, primarily to gather base-line data in relationtoa collaborative study between the Entomology Division, Anti-Malaria Campaignand the Department of Zoology, University of Sri Jayewardenepura on thepotential for a genetic approach for malaria control in Sri Lanka. Eight anophelinespecies were recordedfrom adult catches and lavae sampled. An. subpictusAn. culicifacies and An. varuna were the most predominant species.The only stream with two tributaries in the study area was the permanentand very productive anopheline breeding habitat. Larval and adult anophelinedensities were related to the rainfall received. The larval densities recorded indrought periods were observed to be significantly higher than those recorded inrainy periods (t=4.087, p&lt;O.Ol). August, September and October that recordedrelatively low larval and adult An. culicifacies densities appear to be suitabletimes for field releases of genetically altered An.culicifacies in the area for malariacontrol