1,154 research outputs found
Multiwavelength observations of the Be/X-ray binary 4U1145-619
We report optical and infrared observations of the massive X-ray binary
system 4U1145-619 (V801 Cen) which show that the circumstellar disc of the Be
star component is in decline. Infrared J,H,K,L magnitudes of V801Cen have been
monitored from 1993 March to 1996 April. H alpha spectra have been obtained
throughout the same period. We find that both the infrared excess and the
Balmer emission have been in decline throughout the period of observations. A
13 year optical and X-ray history of the source has been collated, revealing a
possible correlation between the optical and X-ray activity. In addition, we
have used u,v,b,y,beta indices, corrected for both circumstellar and
interstellar effects, to calculate the physical parameters of the underlying B
star.Comment: 8 pages postscript. Accepted by MNRA
Researchers explore Arctic freshwater\u27s role in ocean circulation
A critical, but insufficiently understood, component of global change is the influence of Arctic freshwater input on water mass exchange between the Arctic Ocean and Atlantic and Pacific Oceans. Four of the Earth\u27s 10 largest river systems, the Mackenzie, Ob,Yenisei, and Lena, contribute water to the Arctic shore (Figure 1) from a vast watershed that drains continental interiors. This river discharge flows into the world\u27s largest contiguous continental shelf and supplies over 50% (1823 km3 ) of the riverine input to the Arctic Ocean
Effective Field Theory for Nuclear Physics
I summarize the motivation for the effective field theory approach to nuclear
physics, and highlight some of its recent accomplishments. The results are
compared with those computed in potential models.Comment: Talk delivered at Baryons '98, Bonn, Sept. 22, 1998. 15 pages, 9
figure
The Long and Short of Nuclear Effective Field Theory Expansions
Nonperturbative effective field theory calculations for NN scattering seem to
break down at rather low momenta. By examining several toy models, we clarify
how effective field theory expansions can in general be used to properly
separate long- and short-range effects. We find that one-pion exchange has a
large effect on the scattering phase shift near poles in the amplitude, but
otherwise can be treated perturbatively. Analysis of a toy model that
reproduces 1S0 NN scattering data rather well suggests that failures of
effective field theories for momenta above the pion mass can be due to
short-range physics rather than the treatment of pion exchange. We discuss the
implications this has for extending the applicability of effective field
theories.Comment: 22 pages, 9 figures, references corrected, minor modification
A tetraspecific VHH-based neutralizing antibody modifies disease outcome in three animal models of Clostridium difficile infection
Clostridium difficile infection (CDI), a leading cause of nosocomial infection, is a serious disease in North America, Europe, and Asia. CDI varies greatly from asymptomatic carriage to life-threatening diarrhea, toxic megacolon, and toxemia. The incidence of community-acquired infection has increased due to the emergence of hypervirulent antibiotic-resistant strains. These new strains contribute to the frequent occurrence of disease relapse, complicating treatment, increasing hospital stays, and increasing morbidity and mortality among patients. Therefore, it is critical to develop new therapeutic approaches that bypass the development of antimicrobial resistance and avoid disruption of gut microflora. Here, we describe the construction of a single heteromultimeric VHH-based neutralizing agent (VNA) that targets the two primary virulence factors of Clostridium difficile, toxins A (TcdA) and B (TcdB). Designated VNA2-Tcd, this agent has subnanomolar toxin neutralization potencies for both C. difficile toxins in cell assays. When given systemically by parenteral administration, VNA2-Tcd protected against CDI in gnotobiotic piglets and mice and to a lesser extent in hamsters. Protection from CDI was also observed in gnotobiotic piglets treated by gene therapy with an adenovirus that promoted the expression of VNA2-Tcd
Chemogenomic Profiling of Antileishmanial Efficacy and Resistance in the Related Kinetoplastid Parasite <i>Trypanosoma brucei</i>
The arsenal of drugs used to treat leishmaniasis, caused by Leishmania spp., is limited and beset by emergent resistance and toxicity. Our understanding of drug mode-of-action and potential routes to resistance is also limited. Forward genetic approaches have revolutionised our understanding of drug mode-of-action in the related kinetoplastid parasite, Trypanosoma brucei. Therefore, we screened our genome-scale T. brucei RNAi library for knockdowns that render cells resistant to the current anti-leishmanial drugs, sodium stibogluconate (antimonial), paromomycin, miltefosine and amphotericin-B. Identification of T. brucei orthologues of the known Leishmania antimonial and miltefosine plasma membrane transporters effectively validated our approach, while a cohort of 42 novel drug efficacy determinants provides new insights and serves as a resource
The role of public law-based litigation in tobacco companies' strategies in high-income, FCTC ratifying countries, 2004-14.
BACKGROUND: Tobacco companies use a host of strategies to undermine public health efforts directed to reduce and eliminate smoking. The success, failure and trends in domestic litigation used by tobacco companies to undermine tobacco control are not well understood, with commentators often assuming disputes are trade related or international in nature. We analyse domestic legal disputes involving tobacco companies and public health actors in high-income countries across the last decade to ascertain the types of action and the success or failure of cases, develop effective responses. METHODS: WorldLii, a publicly available online law repository, was used to identify domestic court cases involving tobacco companies from 2004 to 2014, while outcome data from LexisNexis and Westlaw databases were used to identify appeals and trace case history. RESULTS: We identified six domestic cases in the UK, Australia and Canada, noting that the tobacco industry won only one of six cases; a win later usurped by legislative reform and a further court case. Nevertheless, we found cases involve significant resource costs for governments, often progressing across multiple jurisdictional levels. DISCUSSION: We suggest that, in light of our results, while litigation takes up significant time and incurs legal costs for health ministries, policymakers must robustly fend off suggestions that litigation wastes taxpayers' money, pointing to the good prospects of winning such legal battles
Fishing for Prion Protein Function
The prion protein is infamous for its role in devastating neurological diseases, but its normal, physiological function has remained mysterious. A new study uses the experimentally tractable zebrafish model to obtain fresh clues to this puzzle
- …