1,841 research outputs found
Module course: ‘A practical exploration of Creative Thinking Systems’:A Creativity Fellowship Research Project: University of Brighton
Intraperitoneal Enterobius vermicularis Infection: A Case Report
Background: Enterobius vermicularis in an ectopic location usually represents an incidental finding
in tissue specimens in a patient without symptoms. However, the parasite can lead to inflammation
and symptoms in rare cases
An inhomogeneous Josephson phase in thin-film and High-Tc superconductors
In many cases inhomogeneities are known to exist near the metal (or
superconductor)-insulator transition, as follows from well-known domain-wall
arguments. If the conducting regions are large enough (i.e. when the T=0
superconducting gap is much larger than the single-electron level spacing), and
if they have superconducting correlations, it becomes energetically favorable
for the system to go into a Josephson-coupled zero-resistance state before
(i.e. at higher resistance than) becoming a "real" metal. We show that this is
plausible by a simple comparison of the relevant coupling constants. For small
grains in the above sense, the electronic grain structure is washed out by
delocalization and thus becomes irrelevant. When the proposed "Josephson state"
is quenched by a magnetic field, an insulating, rather then a metallic, state
should appear. This has been shown to be consistent with the existing data on
oxide materials as well as ultra-thin films. We discuss the Uemura correlations
versus the Homes law, and derive the former for the large-grain Josephson array
(inhomogenous superconductor) model. The small-grain case behaves like a dirty
homogenous metal. It should obey the Homes law provided that the system is in
the dirty supeconductivity limit. A speculation why that is typically the case
for d-wave superconductors is presented.Comment: Conference proceeding for "Fluctuations in Superconductors" held in
Nazareth, Israel in June, 2007; 6 pages with 1 figure, to appear in Physica
Protein Phylogenetic Analysis of Ca2+/cation Antiporters and Insights into their Evolution in Plants
Cation transport is a critical process in all organisms and is essential for mineral nutrition, ion stress tolerance, and signal transduction. Transporters that are members of the Ca2+/cation antiporter (CaCA) superfamily are involved in the transport of Ca2+ and/or other cations using the counter exchange of another ion such as H+ or Na+. The CaCA superfamily has been previously divided into five transporter families: the YRBG, Na+/Ca2+ exchanger (NCX), Na+/Ca2+, K+ exchanger (NCKX), H+/cation exchanger (CAX), and cation/Ca2+ exchanger (CCX) families, which include the well-characterized NCX and CAX transporters. To examine the evolution of CaCA transporters within higher plants and the green plant lineage, CaCA genes were identified from the genomes of sequenced flowering plants, a bryophyte, lycophyte, and freshwater and marine algae, and compared with those from non-plant species. We found evidence of the expansion and increased diversity of flowering plant genes within the CAX and CCX families. Genes related to the NCX family are present in land plant though they encode distinct MHX homologs which probably have an altered transport function. In contrast, the NCX and NCKX genes which are absent in land plants have been retained in many species of algae, especially the marine algae, indicating that these organisms may share “animal-like” characteristics of Ca2+ homeostasis and signaling. A group of genes encoding novel CAX-like proteins containing an EF-hand domain were identified from plants and selected algae but appeared to be lacking in any other species. Lack of functional data for most of the CaCA proteins make it impossible to reliably predict substrate specificity and function for many of the groups or individual proteins. The abundance and diversity of CaCA genes throughout all branches of life indicates the importance of this class of cation transporter, and that many transporters with novel functions are waiting to be discovered
Stripe formation: A quantum critical point for cuprate superconductors
We discuss the effects of a quantum critical point located nearby optimum
doping and related to local charge segregation (stripe phase). The fluctuations
in the critical region produce at the same time a strong pairing mechanism and
a non-Fermi liquid behavior in the normal phase above the superconducting
critical temperature. Superconductivity is a stabilizing mechanism against
charge ordering, i.e. the incommensurate charge density wave quantum critical
point is unstable with respect to superconductivity. A complete scenario for
the cuprates is presented.Comment: Proceedings of the Cape Cod Conference on "Spectroscopies in Novel
Superconductors, SNS 97", to appear on J. Phys. and Chem. of Solid
Delocalization in Coupled Luttinger Liquids with Impurities
We study effects of quenched disorder on coupled two-dimensional arrays of
Luttinger liquids (LL) as a model for stripes in high-T_c compounds. In the
framework of a renormalization-group analysis, we find that weak inter-LL
charge-density-wave couplings are always irrelevant as opposed to the pure
system. By varying either disorder strength, intra- or inter-LL interactions,
the system can undergo a delocalization transition between an insulator and a
novel strongly anisotropic metallic state with LL-like transport. This state is
characterized by short-ranged charge-density-wave order, the superconducting
order is quasi long-ranged along the stripes and short-ranged in the
transversal direction.Comment: 6 pages, 5 figures, substantially extended and revised versio
Risk Prediction Models for Colorectal Cancer: A Systematic Review.
Colorectal cancer is the second leading cause of cancer-related death in Europe and the United States. Survival is strongly related to stage at diagnosis and population-based screening reduces colorectal cancer incidence and mortality. Stratifying the population by risk offers the potential to improve the efficiency of screening. In this systematic review we searched Medline, EMBASE, and the Cochrane Library for primary research studies reporting or validating models to predict future risk of primary colorectal cancer for asymptomatic individuals. A total of 12,808 papers were identified from the literature search and nine through citation searching. Fifty-two risk models were included. Where reported (n = 37), half the models had acceptable-to-good discrimination (the area under the receiver operating characteristic curve, AUROC >0.7) in the derivation sample. Calibration was less commonly assessed (n = 21), but overall acceptable. In external validation studies, 10 models showed acceptable discrimination (AUROC 0.71-0.78). These include two with only three variables (age, gender, and BMI; age, gender, and family history of colorectal cancer). A small number of prediction models developed from case-control studies of genetic biomarkers also show some promise but require further external validation using population-based samples. Further research should focus on the feasibility and impact of incorporating such models into stratified screening programmes.J Usher-Smith is funded by a National Institute of Health Research (NIHR) Clinical Lectureship and F Walter by an NIHR Clinician Scientist award. J Emery is funded by an Australian National Health and Medical Research Council (NHMRC) Practitioner Fellowship. A Wong has an NHMRC Early Career Fellowship. The views expressed in this publication are those of the authors and not necessarily those of the NHS, the NIHR or the Department of Health.This is the author accepted manuscript. The final version is available from American Association for Cancer Research via http://dx.doi.org/10.1158/1940-6207.CAPR-15-027
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