The Outcome of Supernovae in Massive Binaries; Removed Mass, and its Separation Dependence

The majority of massive stars are formed in binary systems. It is hence reasonable to expect that most core-collapse supernovae (CCSNe) take place in binaries and the existence of a companion star may leave some imprints in observed features. Having this in mind, we have conducted two-dimensional hydrodynamical simulations of the collisions of CCSNe ejecta with the companion star in an almost-equal-mass ($\sim 10M_\odot$) binary to find out possible consequences of such events. In particular we pay attention to the amount of mass removed and its dependence on the binary separation. In contrast to the previous surmise, we find that the companion mass is stripped not by momentum transfer but by shock heating. Up to $25\%$ of the original mass can be removed for the closest separations and the removed mass decreases as $M_{ub} \propto a^{-4.3}$ with the binary separation $a$. By performing some experimental computations with artificially-modified densities of incident ejecta, we show that if the velocity of ejecta is fixed, the density of incident ejecta is the single important parameter that actually determines the removed mass as $M_{ub} \propto \rho_{ej} ^{1.4}$. On the other hand, another set of simulations with modified velocities of incident ejecta demonstrate that the strength of the forward shock, which heats up the stellar material and causes the mass loss of the companion star, is actually the key parameter for the removed mass.Comment: 16 pages, accepted for publication in the Astrophysical Journa

Comprehensive study of ejecta-companion interaction for core-collapse supernovae in massive binaries

We carry out a comprehensive study of supernova ejecta-companion interaction in massive binary systems. We aim to physically understand the kinematics of the interaction and predict observational signatures. To do this we perform simulations over a vast parameter space of binary configurations, varying the masses of the progenitor and companion, structure of the companion, explosion energy, and orbital separation. Our results were not so consistent with classical models by Wheeler et al. 1975, sometimes deviating by an order of magnitude. We construct an alternative simple model which explains the simulated results reasonably well and can be used to estimate impact velocities for arbitrary explosion profiles and companion star structures. We then investigate the long term evolution after the supernova, where the companion can be inflated by the energy injected into the star. We find that the companion can become more than an order of magnitude overluminous straight after the supernova, but quickly fades away after $\sim10$ years and returns to its original luminosity in about a thermal timescale of the star. Finally, we also discuss the possible surface contamination of heavy elements from the slower ejecta.Comment: 24 pages, 21 figures, accepted by the Astrophysical Journa

Effectiveness of SSRIs for GAD in children

Generalized anxiety disorder (GAD) sometimes exists in the background of social withdrawal and school refusal. Although clinical evidence suggests that selective serotonin reuptake inhibitors (SSRIs) are an effective treatment for GAD, they are not officially approved for GAD in Japan. In addition, it has been established that the use of SSRIs increases the risk for suicide and activation syndrome among young individuals. As such, there is currently little domestic clinical experience in prescribing SSRIs to young patients with GAD. The authors report two cases involving 10-year-old patients with GAD who were treated successfully with escitalopram and experienced subsequent improvement in social withdrawal and school refusal. One patient had autistic spectrum disorder and exhibited self-harm associated with anxiety symptoms, requiring careful use of SSRIs under hospitalization. The other patient was treated at an outpatient clinic without any side effects. In each case, improvement of anxiety symptoms with the use of SSRIs facilitated the introduction of psychoeducation and psychotherapy. It is important to accurately diagnose GAD, which may exist in the background of patients exhibiting social withdrawal and school refusal, and to treat the disorder appropriately

Rapid preparation of mutated influenza hemagglutinins for influenza virus pandemic prevention

Influenza viruses have periodically caused pandemic due to frequent mutation of viral proteins. Influenza viruses have two major membrane glycoproteins: hemagglutinin (HA) and neuraminidase (NA). Hemagglutinin plays a crucial role in viral entry, while NA is involved in the process of a viral escape. In terms of developing antiviral drugs, HA is a more important target than NA in the prevention of pandemic, since HA is likely to change the host specificity of a virus by acquiring mutations, thereby to increase the risk of pandemic. To characterize mutated HA functions, current approaches require immobilization of purified HA on plastic wells and carriers. These troublesome methods make it difficult to respond to emerging mutations. In order to address this problem, a yeast cell surface engineering approach was investigated. Using this technology, human HAs derived from various H1N1 subtypes were successfully and rapidly displayed on the yeast cell surface. The yeast-displayed HAs exhibited similar abilities to native influenza virus HAs. Using this system, human HAs with 190E and 225G mutations were shown to exhibit altered recognition specificities from human to avian erythrocytes. This system furthermore allowed direct measurement of HA binding abilities without protein purification and immobilization. Coupled with the ease of genetic manipulation, this system allows the simple and comprehensive construction of mutant protein libraries on yeast cell surface, thereby contributing to influenza virus pandemic prevention

A Keck/DEIMOS Spectroscopy of Lyman Alpha Blobs at Redshift z=3.1

We present the results of an intermediate resolution (~2 angstrom) spectroscopy of a sample of 37 candidate Lyman alpha blobs and emitters at redshift z=3.1 using the DEIMOS spectrograph on the 10 m Keck telescope. The emission lines are detected for all the 37 objects and have variety in their line profiles. The Lyman alpha velocity widths (FWHM) of the 28 objects with higher quality spectra, measured by fitting a single Gaussian profile, are in the range of 150 - 1700 km/s and correlate with the Lyman alpha spatial extents. All the 12 Lyman alpha blobs (>16 arcsec^2) have large velocity widths of > 500 km/s. While there are several possible physical interpretations of the Lyman alpha velocity widths (motion of gravitationally-bound gas clouds, inflows, merging of clumps, or outflows from superwinds), the large velocity widths of the Lyman alpha blobs suggest that they are the sites of massive galaxy formation. If we assume gravitationally-bound gas clouds, the dynamical masses of the Lyman alpha blobs are estimated to be ~10^12 - 10^13 Msun. Even for the case of outflows, the outflow velocities are likely to be the same order of the rotation velocities as inferred from the observational evidence for local starburst galaxies.Comment: Accepted for publication in ApJ

Effect of nalfurafine hydrochloride on the basal pressure of the sphincter of Oddi in anesthetized rabbits

Background: Opioid analgesics, which are classified as μ-opioid receptor agonists, are known to induce spasms or contraction of the sphincter of Oddi (SO), thereby inducing or exacerbating biliary diseases such as biliary obstruction, gallbladder dysfunction, cholelithiasis, pancreatitis, biliary dyskinesia, cholangitis, and cholecystitis. However, effects of κ-opioid receptor agonists on SO contraction have not been clarified. In the present study, we investigated the effect of nalfurafine hydrochloride (nalfurafine), (E)-N-[17-(cyclopropylmethyl)-4,5α-epoxy-3,14-dihydroxymorphinan-6β-yl]-3-(furan-3-yl)-N-methylprop-2-enamide monohydrochloride, a selective κ-opioid receptor agonist, on spontaneous contraction of rabbit SO.Methods: SO contraction was measured using manometry in anesthetized rabbits. Rabbits were anesthetized with intravenous administration of 25 mg/kg sodium pentobarbital. An open tip catheter was inserted into the common bile duct toward the SO ampullae. Saline was perfused through the lumen of the open tip catheter at a constant rate of 6 ml/hr using a syringe pump. Nalfurafine, morphine, and pentazocine were intravenously (i.v.) administered and perfusion pressure was recorded.Results: Morphine (0.3 mg/kg, i.v.) and pentazocine (3 mg/kg, i.v.) were found to increase SO perfusion pressure, suggesting that these opioid analgesics may cause SO contraction. In contrast, nalfurafine (0.2 μg/kg, i.v.) decreased the perfusion pressure, indicating that this κ-opioid receptor agonist suppresses SO contraction.Conclusions: These findings suggest that nalfurafine is unlikely to induce or exacerbate biliary diseases and may be safely used in patients with these disorders

Direct ethanol production from cellulosic materials using a diploid strain of Saccharomyces cerevisiae with optimized cellulase expression

<p>Abstract</p> <p>Background</p> <p>Hydrolysis of cellulose requires the action of the cellulolytic enzymes endoglucanase, cellobiohydrolase and β-glucosidase. The expression ratios and synergetic effects of these enzymes significantly influence the extent and specific rate of cellulose degradation. In this study, using our previously developed method to optimize cellulase-expression levels in yeast, we constructed a diploid <it>Saccharomyces cerevisiae </it>strain optimized for expression of cellulolytic enzymes, and attempted to improve the cellulose-degradation activity and enable direct ethanol production from rice straw, one of the most abundant sources of lignocellulosic biomass.</p> <p>Results</p> <p>The engineered diploid strain, which contained multiple copies of three cellulase genes integrated into its genome, was precultured in molasses medium (381.4 mU/g wet cell), and displayed approximately six-fold higher phosphoric acid swollen cellulose (PASC) degradation activity than the parent haploid strain (63.5 mU/g wet cell). When used to ferment PASC, the diploid strain produced 7.6 g/l ethanol in 72 hours, with an ethanol yield that achieved 75% of the theoretical value, and also produced 7.5 g/l ethanol from pretreated rice straw in 72 hours.</p> <p>Conclusions</p> <p>We have developed diploid yeast strain optimized for expression of cellulolytic enzymes, which is capable of directly fermenting from cellulosic materials. Although this is a proof-of-concept study, it is to our knowledge, the first report of ethanol production from agricultural waste biomass using cellulolytic enzyme-expressing yeast without the addition of exogenous enzymes. Our results suggest that combining multigene expression optimization and diploidization in yeast is a promising approach for enhancing ethanol production from various types of lignocellulosic biomass.</p