1,537 research outputs found
Recapitalizing Banks with Public Funds
Recapitalizing banks in a systemic crisis is a complex medium-term process that requires significant government intervention and careful management at both the strategic and individual bank levels. This paper examines the range of operational and strategic issues involved and the institutional arrangements needed to foster an effective banking system restructuring, as well as maximize the returns on government investment. Recapitalization approaches have varied in the different mixes of direct capital injections and asset purchases and rehabilitation that countries choose. The choice of an appropriate mix is critical to minimizing the expected present value of government outlays net of recoveries. Copyright 2001, International Monetary Fund
Specsim: The MIRI Medium Resolution Spectrometer Simulator
MIRI, the Mid-InfraRed Instrument, is one of four instruments being built for
the James Webb Space Telescope, and is developed jointly between an
EuropeanConsortium and the US. In this paper we present a software data
simulator for one of MIRI's four instruments: the Integral Field Unit (IFU)
Medium Resolution Spectrometer (MIRI-MRS), the first mid-infrared IFU
spectrograph, and one of the first IFUs to be used in a space mission. To give
the MIRI community a preview of the properties of the MIRI-MRS data products
before the telescope is operational, the Specsim tool has been developed to
model, in software, the operation of the spectrometer. Specsim generates
synthetic data frames approximating those which will be taken by the instrument
in orbit. The program models astronomical sources and generates detector frames
using the predicted and measured optical properties of the telescope and MIRI.
These frames can then be used to illustrate and inform a range of operational
activities, including data calibration strategies and the development and
testing of the data reduction software for the MIRI-MRS. Specsim will serve as
a means of communication between the many consortium members by providing a way
to easily illustrate the performance of the spectrometer under different
circumstances, tolerances of components and design scenarios.Comment: 8 pages, 5 figures; A high resolution version is available at
http://www.roe.ac.uk/~npfl/Publications/lgw+06.ps.gz (Changed URL of high-res
version
Latent Heat Recovery Modification from Sodium Acetate Trihydrate due to Structural Changes Caused by Silver Nanoparticles
Phase change materials (PCMs) have great potential as energy storage devices through the storage of thermal energy at low temperatures. Sodium acetate trihydrate (SAT) is a PCM commonly used for storing thermal energy for non-electric personal warmers, and releases that energy as latent heat during the phase transition from a supersaturated liquid state to a solid, crystal state at room temperature. SAT is an inexpensive, non-toxic PCM. These characteristics make SAT ideal for the development of reusable, non-electric neonatal blankets. This application requires careful optimization of the maximum temperature attained by the SAT solution, balanced by a prolonged heat release that will last hours. It is hypothesized that latent heat release will be prolonged if crystal growth rate is slowed via the interference of additives with the crystallization process. In this work we investigate the effects of adding nanoparticles to a solution of SAT and water. We find that the nanoparticles expedite the crystal growth, but that the growth rate of SAT crystals is non-monotonic with increasing nanoparticle concentration. Powder X-ray diffraction data indicate that the crystal structure is not affected with larger size particles are added, but strongly modified with the addition of 10nm size silver nanoparticles
Biological effects of paenilamicin, a secondary metabolite antibiotic produced by the honey bee pathogenic bacterium Paenibacillus larvae
Paenibacillus larvae is the etiological agent of American Foulbrood (AFB) a world-wide distributed devastating disease of the honey bee brood. Previous comparative genome analysis and more recently, the elucidation of the bacterial genome, provided evidence that this bacterium harbors putative functional nonribosomal peptide synthetases (NRPSs) and polyketide synthases (PKSs) and therefore, might produce nonribosomal peptides (NRPs) and polyketides (PKs). Such biosynthesis products have been shown to display a wide-range of biological activities such as antibacterial, antifungal or cytotoxic activity. Herein we present an in silico analysis of the first NRPS/PKS hybrid of P. larvae and we show the involvement of this cluster in the production of a compound named paenilamicin (Pam). For the characterization of its in vitro and in vivo bioactivity, a knock-out mutant strain lacking the production of Pam was constructed and subsequently compared to wild-type species. This led to the identification of Pam by mass spectrometry. Purified Pam-fractions showed not only antibacterial but also antifungal and cytotoxic activities. The latter suggested a direct effect of Pam on honey bee larval death which could, however, not be corroborated in laboratory infection assays. Bee larvae infected with the non-producing Pam strain showed no decrease in larval mortality, but a delay in the onset of larval death. We propose that Pam, although not essential for larval mortality, is a virulence factor of P. larvae influencing the time course of disease. These findings are not only of significance in elucidating and understanding host-pathogen interactions but also within the context of the quest for new compounds with antibiotic activity for drug development.DFG, GRK 1121, Genetische und immunologische Determinanten von Pathogen-Wirt-InteraktionenDFG, EXC 314, Unifying Concepts in Catalysi
Production of the Catechol Type Siderophore Bacillibactin by the Honey Bee Pathogen Paenibacillus larvae
The Gram-positive bacterium Paenibacillus larvae is the etiological agent of
American Foulbrood. This bacterial infection of honey bee brood is a
notifiable epizootic posing a serious threat to global honey bee health
because not only individual larvae but also entire colonies succumb to the
disease. In the recent past considerable progress has been made in elucidating
molecular aspects of host pathogen interactions during pathogenesis of P.
larvae infections. Especially the sequencing and annotation of the complete
genome of P. larvae was a major step forward and revealed the existence of
several giant gene clusters coding for non-ribosomal peptide synthetases which
might act as putative virulence factors. We here present the detailed analysis
of one of these clusters which we demonstrated to be responsible for the
biosynthesis of bacillibactin, a P. larvae siderophore. We first established
culture conditions allowing the growth of P. larvae under iron-limited
conditions and triggering siderophore production by P. larvae. Using a gene
disruption strategy we linked siderophore production to the expression of an
uninterrupted bacillibactin gene cluster. In silico analysis predicted the
structure of a trimeric trithreonyl lactone (DHB-Gly-Thr)3 similar to the
structure of bacillibactin produced by several Bacillus species. Mass
spectrometric analysis unambiguously confirmed that the siderophore produced
by P. larvae is identical to bacillibactin. Exposure bioassays demonstrated
that P. larvae bacillibactin is not required for full virulence of P. larvae
in laboratory exposure bioassays. This observation is consistent with results
obtained for bacillibactin in other pathogenic bacteria
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