1,174 research outputs found
Point-contact Andreev reflection spectroscopy of heavy-fermion-metal/superconductor junctions
Our previous point-contact Andreev reflection studies of the heavy-fermion
superconductor CeCoIn using Au tips have shown two clear features: reduced
Andreev signal and asymmetric background conductance [1]. To explore their
physical origins, we have extended our measurements to point-contact junctions
between single crystalline heavy-fermion metals and superconducting Nb tips.
Differential conductance spectra are taken on junctions with three
heavy-fermion metals, CeCoIn, CeRhIn, and YbAl, each with different
electron mass. In contrast with Au/CeCoIn junctions, Andreev signal is not
reduced and no dependence on effective mass is observed. A possible explanation
based on a two-fluid picture for heavy fermions is proposed. [1] W. K. Park et
al., Phys. Rev. B 72 052509 (2005); W. K. Park et al., Proc. SPIE-Int. Soc.
Opt. Eng. 5932 59321Q (2005); W. K. Park et al., Physica C (in press)
(cond-mat/0606535).Comment: 2 pages, 2 figures, submitted to the SCES conference, Houston, Texas,
USA, May 13-18, 200
Preventable emergency hospital admissions among adults with intellectual disability : comparisons with the general population in England
Purpose
Adults with intellectual disabilities (ID) experience poorer physical health and healthcare quality, but there is limited information on the scope for reducing emergency hospital admissions. We describe overall and preventable emergency admissions for adults with ID compared to the general population and assess differences in primary care management before admission for two common Ambulatory Care Sensitive conditions (ACSCs).
Methods
We used electronic records to study a matched cohort of 16,666 adults with ID and 113,562 age, sex and practice matched controls from 343 English family practices. Incident rate ratios (IRR) from conditional Poisson regression are analysed for all emergency and preventable (ACSC) emergency admissions. Primary care management of lower respiratory (LRTI) and urinary tract (UTI) infections, as exemplar ACSCs, prior to admission are compared in unmatched analysis between adults with and without ID.
Results
The overall rate for emergency admissions for adults with ID versus controls was 182 vs. 68 per 1000/year (IRR=2.82, 95%CI: 2.66–2.98). ACSCs accounted for 33.7% of emergency admissions compared to 17.3% in controls (IRR=5.62, 5.14-6.13); adjusting for comorbidity, smoking and deprivation did not explain the difference (IRR=3.60, 3.25–3.99). Despite adults with ID being at nearly five times higher risk for admissions from LRTI and UTI, they have similar primary care utilisation, investigation and management preceding admission, as the general population.
Conclusion
Adults with ID are at high risk of preventable emergency admissions. Identifying improvements for detection and management of ACSCs in primary care, including lower respiratory and urinary tract infections, could reduce hospitalisations
Scanning Tunneling Spectroscopy in MgB2
We present scanning tunneling microscopy measurements of the surface of
superconducting MgB2 with a critical temperature of 39K. In zero magnetic field
the conductance spectra can be analyzed in terms of the standard BCS theory
with a smearing parameter Gamma. The value of the superconducting gap is 5.2
meV at 4.2 K, with no experimentally significant variation across the surface
of the sample. The temperature dependence of the gap follows the BCS form,
fully consistent with phonon-mediated superconductivity in this novel
superconductor. The application of a magnetic field induces strong
pair-breaking as seen in the conductance spectra in fields up to 6 T.Comment: 4 pages, 4 figure
Brain-penetrant complement inhibition mitigates neurodegeneration in an Alzheimer's disease mouse model
Complement activation is implicated in driving brain inflammation, self-cell damage and progression of injury in Alzheimer's disease and other neurodegenerative diseases. Here, we investigate the impact of brain delivery of a complement-blocking antibody on neurodegeneration in an Alzheimer's mouse model. We engineered a brain-penetrant recombinant antibody targeting the pro-inflammatory membrane attack complex. Systemic administration of this antibody in APPNL-G-F mice reduced brain levels of complement activation products, demonstrating successful brain entry and target engagement. Prolonged treatment decreased synapse loss, amyloid burden and brain inflammatory cytokine levels, concomitant with cognitive improvement compared to controls. These results underscore the potential of brain-penetrant complement-inhibiting drugs as promising therapeutics, targeting downstream of amyloid plaques in Alzheimer's disease
Predominantly Superconducting Origin of Large Energy Gaps in Underdoped Bi2Sr2CaCu2O8-d from Tunneling Spectroscopy
New tunneling data are reported in underdoped Bi2Sr2CaCu2O8-d using
superconductor-insulator-superconductor break junctions. Energy gaps, Delta, of
51+2, 54+2 and 57+3 meV are observed for three crystals with Tc=77, 74, and 70
K respectively. These energy gaps are nearly three times larger than for
overdoped crystals with similar Tc. Detailed examination of tunneling spectra
over a wide doping range from underdoped to overdoped, including the Josephson
IcRn product, indicate that these energy gaps are predominantly of
superconducting origin.Comment: 10 pages, 4 figures, 1 tabl
On the class SI of J-contractive functions intertwining solutions of linear differential equations
In the PhD thesis of the second author under the supervision of the third
author was defined the class SI of J-contractive functions, depending on a
parameter and arising as transfer functions of overdetermined conservative 2D
systems invariant in one direction. In this paper we extend and solve in the
class SI, a number of problems originally set for the class SC of functions
contractive in the open right-half plane, and unitary on the imaginary line
with respect to some preassigned signature matrix J. The problems we consider
include the Schur algorithm, the partial realization problem and the
Nevanlinna-Pick interpolation problem. The arguments rely on a correspondence
between elements in a given subclass of SI and elements in SC. Another
important tool in the arguments is a new result pertaining to the classical
tangential Schur algorithm.Comment: 46 page
Implications of the problem orientated medical record (POMR) for research using electronic GP databases: a comparison of the Doctors Independent Network Database (DIN) and the General Practice Research Database (GPRD).
Background
The General Practice Research Database (GPRD) and Doctor's Independent Network Database (DIN), are large electronic primary care databases compiled in the UK during the 1990s. They provide a valuable resource for epidemiological and health services research. GPRD (based on VAMP) presents notes as a series of discrete episodes, whereas DIN is based on a system (MEDITEL) that used a Problem Orientated Medical Record (POMR) which links prescriptions to diagnostic problems. We have examined the implications for research of these different underlying philosophies.
Methods
Records of 40,183 children from 141 practices in DIN and 76,310 from 464 practices in GRPD who were followed to age 5 were used to compare the volume of recording of prescribing and diagnostic codes in the two databases. To assess the importance and additional value of the POMR within DIN, the appropriateness of diagnostic linking to skin emollient prescriptions was investigated.
Results
Variation between practices for both the number of days on which prescriptions were issued and diagnoses were recorded was marked in both databases. Mean number of "prescription days" during the first 5 years of life was similar in DIN (19.5) and in GPRD (19.8), but the average number of "diagnostic days" was lower in DIN (15.8) than in GPRD (22.9). Adjustment for linkage increased the average "diagnostic days" to 23.1 in DIN. 32.7% of emollient prescriptions in GPRD appeared with an eczema diagnosis on the same day compared to only 19.4% in DIN; however, 86.4% of prescriptions in DIN were linked to an earlier eczema diagnosis. More specifically 83% of emollient prescriptions appeared under a problem heading of eczema in the 121 practices that were using problem headings satisfactorily.
Conclusion
Prescribing records in DIN and GPRD are very similar, but the usage of diagnostic codes is more parsimonious in DIN because of its POMR structure. Period prevalence rates will be underestimated in DIN unless this structure is taken into account. The advantage of the POMR is that in 121 of 141 practices using problem headings as intended, most prescriptions can be linked to a problem heading providing a specific reason for their issue
- …