Chemical chronology of the Southern Coalsack

We demonstrate how the observed H2O ice column densities toward three dense globules in the Southern Coalsack could be used to constrain the ages of these sources. We derive ages of ~10^5 yr, in agreement with dynamical studies of these objects. We have modelled the chemical evolution of the globules, and show how the molecular abundances are controlled by both the gas density and the initial chemical conditions as the globules formed. Based on our derived ages, we predict the column densities of several species of interest. These predictions should be straightforward to test by performing molecular line observationsComment: 10 pages, 4 figures, in press at MNRA

Relating Physical Observables in QCD without Scale-Scheme Ambiguity

We discuss the St\"uckelberg-Peterman extended renormalization group equations in perturbative QCD, which express the invariance of physical observables under renormalization-scale and scheme-parameter transformations. We introduce a universal coupling function that covers all possible choices of scale and scheme. Any perturbative series in QCD is shown to be equivalent to a particular point in this function. This function can be computed from a set of first-order differential equations involving the extended beta functions. We propose the use of these evolution equations instead of perturbative series for numerical evaluation of physical observables. This formalism is free of scale-scheme ambiguity and allows a reliable error analysis of higher-order corrections. It also provides a precise definition for $\Lambda_{\overline{\rm MS}}$ as the pole in the associated 't Hooft scheme. A concrete application to $R(e^+e^- \to {\rm hadrons})$ is presented.Comment: Plain TEX, 4 figures (available upon request), 22 pages, DOE/ER/40322-17

A modified technique of orthotopic transplant of the kidney in rabbits

In this study kidneys were harvested from bred-for-research cats weighing 4 to 5 kg. General principles of donor bilateral nephrectomy en bloc with aorta, vena cava, renal vessels, and ureters were followed. After the harvest the grafts were placed in lactated Ringer slush. A cuff was prepared on the renal vein over a 10 French plastic tube. The aorta was divided and left in connection with the renal artery at each side. Twenty female checkered Flemish giant rabbits weighing 4.0-6.0 kg served as recipients. After premedication with 40 mg/kg of ketamine, anesthesia was maintained with repeated doses (every 10-15 min) of a 0.1-mL mixture of 5 parts ketamine and 1 part acepromazine diluted 50% in a normal saline. Arterial pressure, CVP, blood gases, and temperature were monitored. Through a limited midline incision a native left nephrectomy was performed. The venous anastomosis was performed with a cuff technique without clamping the vena cava (which causes severe hemodynamic instability); the anastomotic time was 2-3 min. The arterial anastomosis was performed with an end-to-side aorta-to-aorta anastomosis; the anastomotic time was 5 to 7 min. There were no episodes of venous or arterial thrombosis. The donor procedure took approximately 40 min, and the backtable preparation of the graft an additional 45 to 60 min. Preparation of the recipient for the anastomosis took 15 min and the anastomotic time (warm ischemia) was 13 +/- 5 min. In this model suitable for xenograft research the duration of the surgery in the recipient has been greatly reduced because of (1) the previous backtable preparation of the graft, and (2) the cuff technique used for venous anastomosis. The present anesthesia regimen and careful hemodynamic monitoring were also important in the success of this model

Inclusive B-Meson Production in e^+ e^- and p p-bar Collisions

We provide nonperturbative fragmentation functions for B mesons, both at leading and next-to-leading order in the MS-bar factorization scheme with five massless quark flavors. They are determined by fitting the fractional energy distribution of B mesons inclusively produced in e^+ e^- annihilation at CERN LEP1. Theoretical predictions for the inclusive production of B mesons with high transverse momenta in p p-bar scattering obtained with these fragmentation functions nicely agree, both in shape and normalization, with data recently taken at the Fermilab Tevatron.Comment: 20 pages (Latex), 6 figures (Postscript

Contribution of brown dwarfs and white dwarfs to recent microlensing observations and to the halo mass budget

We examine the recent results of the MACHO collaboration towards the Large Magellanic Cloud (Alcock et al. 1996) in terms of a halo brown dwarf or white dwarf population. The possibility for most of the microlensing events to be due to brown dwarfs is totally excluded by large-scale kinematic properties. The white dwarf scenario is examined in details in the context of the most recent white dwarf cooling theory (Segretain et al. 1994) which includes explicitely the extra source of energy due to carbon-oxygen differentiation at crystallization, and the subsequent Debye cooling. We show that the observational constraints arising from the luminosity function of high-velocity white dwarfs in the solar neighborhood and from the recent HST deep field counts are consistent with a white dwarf contribution to the halo missing mass as large as 50 %, provided i) an IMF strongly peaked around 1.7 Msol and ii) a halo age older than 18 Gyr.Comment: 14 pages, 2 Postscript figures, to be published in Astrophysical Journal Letters, minor revision in tex

Origin of Tidal Dissipation in Jupiter: II. the Value of Q

The process of tidal dissipation inside Jupiter is not yet understood. Its tidal quality factor ($Q$) is inferred to lie between $10^5$ and $10^6$. We examine effects of inertial-modes on tidal dissipation in a neutrally bouyant, core-less, uniformly rotating planet. The rate of dissipation caused by resonantly excited inertial-modes depends on the following three parameters: how well they are coupled to the tidal potential, how strongly they are dissipated (by the turbulent viscosity), and how densely distributed they are in frequency. We find that as a function of tidal frequency, the $Q$ value exhibits large fluctuations, with its maximum value set by the group of inertial-modes that have a typical offset from an exact resonance of order their turbulent damping rates. In our model, inertial-modes shed their tidally acquired energy very close to the surface within a narrow latitudinal zone (the 'singularity belt'), and the tidal luminosity escapes freely out of the planet. Strength of coupling between the tidal potential and inertial-modes is sensitive to the presence of density discontinuities inside Jupiter. In the case of a discreet density jump (as may be caused by the transition between metallic and molecular hydrogen), we find a time-averaged $Q \sim 10^7$. Even though it remains unclear whether tidal dissipation due to resonant inertial-modes is the correct answer to the problem, it is impressive that our simple treatment here already leads to three to five orders of magnitude stronger damping than that from the equilibrium tide. Moreover, our conclusions are not affected by the presence of a small solid core, a different prescription for the turbulent viscosity, or nonlinear mode coupling, but they depend critically on the static stability in the upper atmosphere of Jupiter.Comment: 27 pages, incl. 11 figures, ApJ in print, expanded discussions (nonlinearity, radiative envelope

On an asymptotic estimate of the nn-loop correction in perturbative QCD

A recently proposed method of estimating the asymptotic behaviour of QCD perturbation theory coefficients is critically reviewed and shown to contain numerous invalid mathematical operations and unsubstantiated assumptions. We discuss in detail why this procedure, based solely on renormalization group (RG) considerations and analyticity constraints, cannot lead to such estimates. We stress the importance of correct renormalization scheme (RS) dependence of any meaningful asymptotic estimate and argue that the unambiguous summation of QCD perturbation expansions for physical quantities requires information from outside of perturbation theory itself.Comment: PRA-HEP-92/17, Latex, 20 pages of text plus 5 figures contained in 5 separate PS files. Four of them (corresponding to Figs.1,2,3,5) are appended at the end of this file, the (somewhat larger one) corresponding to Fig.4 can be obtained from any of the mentioned E-mail addresses upon request. E-mail connections: J. Chyla - [email protected]) or h1kchy@dhhdesy3 P. Kolar - [email protected]

KSHV-TK is a tyrosine kinase that disrupts focal adhesions and induces Rho-mediated cell contraction.

This is the accepted manuscript. The final version is available from Wiley at http://onlinelibrary.wiley.com/doi/10.15252/embj.201490358/abstract.Paradoxically, the thymidine kinase (TK) encoded by Kaposi sarcoma-associated herpesvirus (KSHV) is an extremely inefficient nucleoside kinase, when compared to TKs from related herpesviruses. We now show that KSHV-TK, in contrast to HSV1-TK, associates with the actin cytoskeleton and induces extensive cell contraction followed by membrane blebbing. These dramatic changes in cell morphology depend on the auto-phosphorylation of tyrosines 65, 85 and 120 in the N-terminus of KSHV-TK. Phosphorylation of tyrosines 65/85 and 120 results in an interaction with Crk family proteins and the p85 regulatory subunit of PI3-Kinase, respectively. The interaction of Crk with KSHV-TK leads to tyrosine phoshorylation of this cellular adaptor. Auto-phosphorylation of KSHV-TK also induces a loss of FAK and paxillin from focal adhesions, resulting in activation of RhoA-ROCK signalling to myosin II and cell contraction. In the absence of FAK or paxillin, KSHV-TK has no effect on focal adhesion integrity or cell morphology. Our observations demonstrate that by acting as a tyrosine kinase, KSHV-TK modulates signalling and cell morphology.This work was supported by Medical Research Council grant G0701185 to PGS and MBG. M.W is supported by Cancer Research UK

Media outlets and their moguls: why concentrated individual or family ownership is bad for editorial independence

This article investigates the levels of owner influence in 211 different print and broadcast outlets in 32 different European media markets. Drawing on the literature from industrial organisation, it sets out reasons why we should expect greater levels of influence where ownership of individual outlets is concentrated; where it is concentrated in the hands of individuals or families; and where ownership groups own multiple outlets in the same media market. Conversely, we should expect lower levels of influence where ownership is dispersed between transnational companies. The articles uses original data on the ownership structures of these outlets, and combines it with reliable expert judgments as to the level of owner influence in each of the outlets. These hypotheses are tested and confirmed in a multilevel regression model of owner influence. The findings are relevant for policy on ownership limits in the media, and for the debate over transnational versus local control of media