8,143 research outputs found
A sound card based multi-channel frequency measurement system
For physical processes which express themselves as a frequency, for example
magnetic field measurements using optically-pumped alkali-vapor magnetometers,
the precise extraction of the frequency from the noisy signal is a classical
problem. We describe herein a frequency measurement system based on an
inexpensive commercially available computer sound card coupled with a software
single-tone estimator which reaches Cram\'er--Rao limited performance, a
feature which commercial frequency counters often lack. Characterization of the
system and examples of its successful application to magnetometry are
presented.Comment: 4 pages, 3 figures, 1 tabl
Resonant Formation of Molecules in Deuterium: An Atomic Beam Measurement of Muon Catalyzed dt Fusion
Resonant formation of molecules in collisions of muonic tritium
() on D was investigated using a beam of atoms,
demonstrating a new direct approach in muon catalyzed fusion studies. Strong
epithermal resonances in formation were directly revealed for the
first time. From the time-of-flight analysis of fusion
events, a formation rate consistent with times the theoretical prediction was obtained. For the largest
peak at a resonance energy of eV, this corresponds to a rate
of s, more than an order of magnitude larger
than those at low energies.Comment: To appear in Phys. Rev. Let
Impact of the urgent care telephone service NHS 111 pilot sites: a controlled before and after study
Objectives To measure the impact of the urgent care telephone service NHS 111 on the emergency and urgent care system.
Design Controlled before and after study using routine data.
Setting Four pilot sites and three control sites covering a total population of 3.6 million in England, UK.
Participants and data Routine data on 36 months of use of emergency ambulance service calls and incidents, emergency department attendances, urgent care contacts (general practice (GP) out of hours, walk in and urgent care centres) and calls to the telephone triage service NHS direct.
Intervention NHS 111, a new 24 h 7 day a week telephone service for non-emergency health problems, operated by trained non-clinical call handlers with clinical support from nurse advisors, using NHS Pathways software to triage calls to different services and home care.
Main outcomes Changes in use of emergency and urgent care services.
Results NHS 111 triaged 277 163 calls in the first year of operation for a population of 1.8 million. There was no change overall in emergency ambulance calls, emergency department attendances or urgent care use. There was a 19.3% reduction in calls to NHS Direct (95% CI −24.6% to −14.0%) and a 2.9% increase in emergency ambulance incidents (95% CI 1.0% to 4.8%). There was an increase in activity overall in the emergency and urgent care system in each site ranging 4.7–12%/month and this remained when assuming that NHS 111 will eventually take all NHS Direct and GP out of hours calls.
Conclusions In its first year of operation in four pilot sites NHS 111 did not deliver the expected system benefits of reducing calls to the 999 ambulance service or shifting patients to urgent rather than emergency care. There is potential that this type of service increases overall demand for urgent care
Consistent treatment of hydrophobicity in protein lattice models accounts for cold denaturation
The hydrophobic effect stabilizes the native structure of proteins by
minimizing the unfavourable interactions between hydrophobic residues and water
through the formation of a hydrophobic core. Here we include the entropic and
enthalpic contributions of the hydrophobic effect explicitly in an implicit
solvent model. This allows us to capture two important effects: a length-scale
dependence and a temperature dependence for the solvation of a hydrophobic
particle. This consistent treatment of the hydrophobic effect explains cold
denaturation and heat capacity measurements of solvated proteins.Comment: Added and corrected references for design procedure in main text (p.
2) and in Supplemental Information (p. 8
Production of a novel medium chain length Poly(3-hydroxyalkanoate) using unprocessed biodiesel waste and its evaluation as a tissue engineering scaffold
This study demonstrated the utilisation of unprocessed biodiesel waste as a carbon feedstock for Pseudomonas mendocina CH50, for the production of PHAs. A PHA yield of 39.5% CDM was obtained using 5% (v/v) biodiesel waste substrate. Chemical analysis confirmed that the polymer produced was poly(3-hydroxyhexanoate-co-3-hydroxyoctanoate-co-3- hydroxydecanoate-co-3-hydroxydodecanoate) or P(3HHx-3HO-3HD-3HDD). P(3HHx-3HO- 3HD-3HDD) was further characterised and evaluated for its use as a tissue engineering scaffold (TES). This study demonstrated that P(3HHx-3HO-3HD-3HDD) was biocompatible with the C2C12 (myoblast) cell line. In fact, the % cell proliferation of C2C12 on the P(3HHx-3HO-3HD-3HDD) scaffold was 72% higher than the standard tissue culture plastic confirming that this novel PHA was indeed a promising new material for soft tissue engineering
Inhibition of double-strand break non-homologous end-joining by cisplatin adducts in human cell extracts
The effect of cis-diaminedichloroplatinum(II) (cisplatin) DNA damage on the repair of double-strand breaks by non-homologous end-joining (NHEJ) was determined using cell-free extracts. NHEJ was dramatically decreased when plasmid DNA was damaged to contain multiple types of DNA adducts, along the molecule and at the termini, by incubation of DNA with cisplatin; this was a cisplatin concentration-dependent effect. We investigated the effect a single GTG cisplatination site starting 10 bp from the DNA termini would have when surrounded by the regions of AT-rich DNA which were devoid of the major adduct target sequences. Cisplatination of a substrate containing short terminal 13–15 bp AT-rich sequences reduced NHEJ to a greater extent than that of a substrate with longer (31–33 bp) AT-rich sequences. However, cisplatination at the single GTG site within the AT sequence had no significant effect on NHEJ, owing to the influence of additional minor monoadduct and dinucleotide adduct sites within the AT-rich region and owing to the influence of cisplatination at sites upstream of the AT-rich regions. We then studied the effect on NHEJ of one cis-[Pt(NH(3))(2){d(GpTpG)-N7(1),-N7(3)} [abbreviated as 1,3-d(GpTpG)] cisplatin adduct in the entire DNA molecule, which is more reflective of the situation in vivo during concurrent chemoradiation. The presence of a single 1,3-d(GpTpG) cisplatin adduct 10 bases from each of the two DNA ends to be joined resulted in a small (30%) but significant decrease in NHEJ efficiency. This process, which was DNA-dependent protein kinase and Ku dependent, may in part explain the radiosensitizing effect of cisplatin administered during concurrent chemoradiation
Long-range/short-range separation of the electron-electron interaction in density functional theory
By splitting the Coulomb interaction into long-range and short-range
components, we decompose the energy of a quantum electronic system into
long-range and short-range contributions. We show that the long-range part of
the energy can be efficiently calculated by traditional wave function methods,
while the short-range part can be handled by a density functional. The analysis
of this functional with respect to the range of the associated interaction
reveals that, in the limit of a very short-range interaction, the short-range
exchange-correlation energy can be expressed as a simple local functional of
the on-top pair density and its first derivatives. This provides an explanation
for the accuracy of the local density approximation (LDA) for the short-range
functional. Moreover, this analysis leads also to new simple approximations for
the short-range exchange and correlation energies improving the LDA.Comment: 18 pages, 14 figures, to be published in Phys. Rev.
Cluster diagonalization in systematically expanded Hilbert spaces: application to models of correlated electrons
A method of cluster diagonalization in a systematically expanded Hilbert
space is described. We discuss some applications of this procedure to models of
high-T_c superconductors, like the t - J and one and three bands Hubbard models
in two dimensions. The results obtained with this method are compared against
results obtained with other techniques dealing with truncated Hilbert spaces.
The relation between this method of diagonalization in a reduced Hilbert space,
and perturbation theory and variational techniques is also discussed.Comment: 26 pages + 12 figures, available upon request, LATEX, preprint
ORNL/CCIP/93/
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