388 research outputs found
Credit Card Usage of College Students: Evidence from Louisiana State University (Research Information Sheet #107)
In recent years, there has been a dramatic growth in credit card usage among college students. How are Louisiana State University undergraduates using credit cards? Are LSU students managing credit card debt wisely? What can LSU do to offer the appropriate kinds of help to enable students to be financially literate? These are the issues addressed in this publication.https://digitalcommons.lsu.edu/agcenter_researchinfosheets/1007/thumbnail.jp
The structures of E. coli NfsA bound to the antibiotic nitrofurantoin; to 1,4-benzoquinone and to FMN
NfsA is a dimeric flavoprotein that catalyses the reduction in nitroaromatics and quinones by NADPH. This reduction is required for the activity of nitrofuran antibiotics. The crystal structure of free Escherichia coli NfsA and several homologues have been determined previously, but there is no structure of the enzyme with ligands. We present here crystal structures of oxidised E. coli NfsA in the presence of several ligands, including the antibiotic nitrofurantoin. Nitrofurantoin binds with the furan ring, rather than the nitro group that is reduced, near the N5 of the FMN. Molecular dynamics simulations show that this orientation is only favourable in the oxidised enzyme, while potentiometry suggests that little semiquinone is formed in the free protein. This suggests that the reduction occurs by direct hydride transfer from FMNH(−) to nitrofurantoin bound in the reverse orientation to that in the crystal structure. We present a model of nitrofurantoin bound to reduced NfsA in a viable hydride transfer orientation. The substrate 1,4-benzoquinone and the product hydroquinone are positioned close to the FMN N5 in the respective crystal structures with NfsA, suitable for reaction, but are mobile within the active site. The structure with a second FMN, bound as a ligand, shows that a mobile loop in the free protein forms a phosphate-binding pocket. NfsA is specific for NADPH and a similar conformational change, forming a phosphate-binding pocket, is likely to also occur with the natural cofactor
The MAJORANA DEMONSTRATOR: A Search for Neutrinoless Double-beta Decay of Germanium-76
The {\sc Majorana} collaboration is searching for neutrinoless double beta
decay using Ge, which has been shown to have a number of advantages in
terms of sensitivities and backgrounds. The observation of neutrinoless
double-beta decay would show that lepton number is violated and that neutrinos
are Majorana particles and would simultaneously provide information on neutrino
mass. Attaining sensitivities for neutrino masses in the inverted hierarchy
region, meV, will require large, tonne-scale detectors with extremely
low backgrounds, at the level of 1 count/t-y or lower in the region of
the signal. The {\sc Majorana} collaboration, with funding support from DOE
Office of Nuclear Physics and NSF Particle Astrophysics, is constructing the
{\sc Demonstrator}, an array consisting of 40 kg of p-type point-contact
high-purity germanium (HPGe) detectors, of which 30 kg will be enriched
to 87% in Ge. The {\sc Demonstrator} is being constructed in a clean
room laboratory facility at the 4850' level (4300 m.w.e.) of the Sanford
Underground Research Facility (SURF) in Lead, SD. It utilizes a compact graded
shield approach with the inner portion consisting of ultra-clean Cu that is
being electroformed and machined underground. The primary aim of the {\sc
Demonstrator} is to show the feasibility of a future tonne-scale measurement in
terms of backgrounds and scalability.Comment: Proceedings for the MEDEX 2013 Conferenc
Low Background Signal Readout Electronics for the MAJORANA DEMONSTRATOR
The MAJORANA DEMONSTRATOR is a planned 40 kg array of Germanium detectors
intended to demonstrate the feasibility of constructing a tonne-scale
experiment that will seek neutrinoless double beta decay () in
. Such an experiment would require backgrounds of less than 1
count/tonne-year in the 4 keV region of interest around the 2039 keV Q-value of
the decay. Designing low-noise electronics, which must be placed
in close proximity to the detectors, presents a challenge to reaching this
background target. This paper will discuss the MAJORANA collaboration's
solutions to some of these challenges
Status of the MAJORANA DEMONSTRATOR experiment
The MAJORANA DEMONSTRATOR neutrinoless double beta-decay experiment is
currently under construction at the Sanford Underground Research Facility in
South Dakota, USA. An overview and status of the experiment are given.Comment: 8 pages, proceeding from VII International Conference on
Interconnections between Particle Physics and Cosmology (PPC 2013), submitted
to AIP proceeding
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