1,579 research outputs found
The prevalence of tenosynovitis of the interosseous tendons of the hand in patients with rheumatoid arthritis.
AIM: The aim of this study was to establish the prevalence of tenosynovitis affecting the interosseous tendons of the hand in a rheumatoid arthritis (RA) population and to assess for association with metacarpophalangeal (MCP) joint synovitis, flexor tendon tenosynovitis or ulnar drift. METHODS: Forty-four patients with RA underwent hand MRI along with 20 normal controls. Coronal 3D T1 VIBE sequences pre- and post-contrast were performed and reconstructed. The presence of interosseous tendon tenosynovitis was recorded alongside MCP joint synovitis, flexor tendon tenosynovitis and ulnar drift. RESULTS: Twenty-one (47.7 %) patients with RA showed interosseous tendon tenosynovitis. Fifty-two (14.8 %) interosseous tendons showed tenosynovitis amongst the RA patients. Interosseous tendon tenosynovitis was more commonly seen in association with adjacent MCP joint synovitis (p < 0.001), but nine MCP joints (5.1 %) showed adjacent interosseous tenosynovitis in the absence of joint synovitis. Interosseous tendon tenosynovitis was more frequently seen in fingers which also showed flexor tendon tenosynovitis (p < 0.001) and in patients with ulnar drift of the fingers (p = 0.01). CONCLUSION: Tenosynovitis of the hand interosseous tendons was found in 47.7 % of patients with RA. In the majority of cases this was adjacent to MCP joint synovitis; however, interosseous tendon tenosynovitis was also seen in isolation. KEY POINTS: • Tenosynovitis of the interosseous tendons of the hand occurs in rheumatoid arthritis. • Interosseous tendon tenosynovitis has a prevalence of 47.7 % in patients with RA. • Interosseous tendon tenosynovitis is related to MCP joint synovitis in the adjacent joints
Ultrasound-detectable grey scale synovitis predicts future fulfilment of the 2010 ACR/EULAR RA classification criteria in patients with new-onset undifferentiated arthritis
Objective: To determine the clinical outcomes for patients with new-onset undifferentiated arthritis (UA), not fulfilling the 2010 American College of Rheumatology (ACR)/European League Against Rheumatism (EULAR) rheumatoid arthritis (RA) classification criteria, and the clinical and imaging predictors of disease progression in these patients. Methods: A prospective observational study was conducted in treatment-naïve UA patients. Baseline ultrasound involved semiquantitative assessment of grey scale (GS) synovitis and power Doppler activity (PD) at 26 joints. Outcomes were fulfilment of 2010 RA criteria (joint involvement determined clinically) and initiation of methotrexate over 12 months. Cox proportional hazards analysis was used to investigate predictors of outcome. Results: Of 60 patients, 13(22%) progressed to RA and 32(53%) ever received methotrexate. Analyses of predictors of outcome were conducted in the subgroup (n=41) of patients with complete baseline data. The presence of GS was associated with progression to RA and methotrexate use: HRs (95% CI) were 1.25(1.07 to 1.45) and 1.16(1.02 to 1.32), respectively, for the number of joints with GS≥ grade 2 after adjustment for swollen joints. PD was not predictive in the low levels at which it was observed. Progression to RA was also associated with fulfilment of the 2010 criteria using ultrasound synovitis for enumerating joint involvement, higher baseline disability and radiographic erosion. Conclusions: This is the first report of ultrasound findings in early UA (defined by presence of clinical synovitis and non-fulfilment of 2010 RA criteria). A significant proportion of patients with UA progressed to RA and/or required methotrexate. GS synovitis was predictive of disease progression
The connection between superconducting phase correlations and spin excitations in YBaCuO: A magnetic field study
One of the most striking universal properties of the
high-transition-temperature (high-) superconductors is that they are all
derived from the hole-doping of their insulating antiferromagnetic (AF) parent
compounds. From the outset, the intimate relationship between magnetism and
superconductivity in these copper-oxides has intrigued researchers. Evidence
for this link comes from neutron scattering experiments that show the
unambiguous presence of short-range AF correlations (excitations) in cuprate
superconductors. Even so, the role of such excitations in the pairing mechanism
and superconductivity is still a subject of controversy. For
YBaCuO, where controls the hole-doping level, the most
prominent feature in the magnetic excitations spectra is the ``resonance''.
Here we show that for underdoped YBaCuO, where and
are below the optimal values, modest magnetic fields suppress the resonance
significantly, much more so for fields approximately perpendicular rather than
parallel to the CuO planes. Our results indicate that the resonance
measures pairing and phase coherence, suggesting that magnetism plays an
important role in the superconductivity of cuprates. The persistence of a field
effect above favors mechanisms with preformed pairs in the normal state
of underdoped cuprates.Comment: 12 pages, 4 figures, Nature (in press
Criticality in correlated quantum matter
At quantum critical points (QCP)
\cite{Pfeuty:1971,Young:1975,Hertz:1976,Chakravarty:1989,Millis:1993,Chubukov:1
994,Coleman:2005} there are quantum fluctuations on all length scales, from
microscopic to macroscopic lengths, which, remarkably, can be observed at
finite temperatures, the regime to which all experiments are necessarily
confined. A fundamental question is how high in temperature can the effects of
quantum criticality persist? That is, can physical observables be described in
terms of universal scaling functions originating from the QCPs? Here we answer
these questions by examining exact solutions of models of correlated systems
and find that the temperature can be surprisingly high. As a powerful
illustration of quantum criticality, we predict that the zero temperature
superfluid density, , and the transition temperature, , of
the cuprates are related by , where the exponent
is different at the two edges of the superconducting dome, signifying the
respective QCPs. This relationship can be tested in high quality crystals.Comment: Final accepted version not including minor stylistic correction
Single and two-particle energy gaps across the disorder-driven superconductor-insulator transition
The competition between superconductivity and localization raises profound
questions in condensed matter physics. In spite of decades of research, the
mechanism of the superconductor-insulator transition (SIT) and the nature of
the insulator are not understood. We use quantum Monte Carlo simulations that
treat, on an equal footing, inhomogeneous amplitude variations and phase
fluctuations, a major advance over previous theories. We gain new microscopic
insights and make testable predictions for local spectroscopic probes. The
energy gap in the density of states survives across the transition, but
coherence peaks exist only in the superconductor. A characteristic pseudogap
persists above the critical disorder and critical temperature, in contrast to
conventional theories. Surprisingly, the insulator has a two-particle gap scale
that vanishes at the SIT, despite a robust single-particle gap.Comment: 7 pages, 5 figures (plus supplement with 4 pages, 5 figures
Warped Riemannian metrics for location-scale models
The present paper shows that warped Riemannian metrics, a class of Riemannian
metrics which play a prominent role in Riemannian geometry, are also of
fundamental importance in information geometry. Precisely, the paper features a
new theorem, which states that the Rao-Fisher information metric of any
location-scale model, defined on a Riemannian manifold, is a warped Riemannian
metric, whenever this model is invariant under the action of some Lie group.
This theorem is a valuable tool in finding the expression of the Rao-Fisher
information metric of location-scale models defined on high-dimensional
Riemannian manifolds. Indeed, a warped Riemannian metric is fully determined by
only two functions of a single variable, irrespective of the dimension of the
underlying Riemannian manifold. Starting from this theorem, several original
contributions are made. The expression of the Rao-Fisher information metric of
the Riemannian Gaussian model is provided, for the first time in the
literature. A generalised definition of the Mahalanobis distance is introduced,
which is applicable to any location-scale model defined on a Riemannian
manifold. The solution of the geodesic equation is obtained, for any Rao-Fisher
information metric defined in terms of warped Riemannian metrics. Finally,
using a mixture of analytical and numerical computations, it is shown that the
parameter space of the von Mises-Fisher model of -dimensional directional
data, when equipped with its Rao-Fisher information metric, becomes a Hadamard
manifold, a simply-connected complete Riemannian manifold of negative sectional
curvature, for . Hopefully, in upcoming work, this will be
proved for any value of .Comment: first version, before submissio
<i>Trypanosoma brucei rhodesiense</i> transmitted by a single tsetse fly bite in vervet monkeys as a model of human African trypanosomiasis
Sleeping sickness is caused by a species of trypanosome blood parasite that is transmitted by tsetse flies. To understand better how infection with this parasite leads to disease, we provide here the most detailed description yet of the course of infection and disease onset in vervet monkeys. One infected tsetse fly was allowed to feed on each host individual, and in all cases infections were successful. The characteristics of infection and disease were similar in all hosts, but the rate of progression varied considerably. Parasites were first detected in the blood 4-10 days after infection, showing that migration of parasites from the site of fly bite was very rapid. Anaemia was a key feature of disease, with a reduction in the numbers and average size of red blood cells and associated decline in numbers of platelets and white blood cells. One to six weeks after infection, parasites were observed in the cerebrospinal fluid (CSF), indicating that they had moved from the blood into the brain; this was associated with a white cell infiltration. This study shows that fly-transmitted infection in vervets accurately mimics human disease and provides a robust model to understand better how sleeping sickness develops
Comorbidities in Anti-Cyclic Citrullinated Peptide Positive At-Risk Individuals Do Not Differ from Those Patients with Early Inflammatory Arthritis
Objectives: To compare comorbidities in a cohort of cyclic citrullinated peptide (CCP) antibody positive patients without or prior to onset of inflammatory arthritis (IA) to those in patients with early IA. Methods: Baseline data from two established cohorts were used. The first recruited people at risk of IA: CCP antibody positive cases without IA (CCP Cohort, n = 296). The second cohort [the Inflammatory Arthritis CONtinuum study (IACON)] recruited patients with early IA (n = 725). Proportions of patients with given comorbidities were compared between cohorts and then logistic regression was used to determine odds ratios (OR) for the CCP cohort having specific comorbidities, compared to IACON patients. Analyses adjusted for gender, age, smoking status, and body mass index. Results: Patients from the CCP cohort were younger (mean age 50, compared to 53 years). The proportion of patients with at least one comorbidity was higher in the IACON than the CCP cohort: (40% compared to 24%, respectively). Results of logistic regression analyses suggested the odds of hypertension, taking a lipid-lowering agent, ischemic heart disease, cerebrovascular disease, lung disease, and diabetes were not increased in either cohort. However, patients in the CCP cohort were more likely to be taking an antidepressant (OR = 1.62, 95% CI 1.03, 2.56, p = 0.037). Conclusion: There was no significant difference in comorbidities among people with CCP antibodies but without IA, compared to those of patients with established IA
On the (anisotropic) uniform metallic ground states of fermions interacting through arbitrary two-body potentials in d dimensions
We demonstrate that the skeleton of the Fermi surface S_{F;s} pertaining to a
uniform metallic ground state (corresponding to fermions with spin index s) is
determined by the Hartree-Fock contribution to the dynamic self-energy. The
Fermi surface S_{F;s} consists of all points which in addition to satisfying
the quasi-particle equation in terms of the Hartree-Fock self-energy, fulfill
the equation S_{s}(k) = 0, where S_{s}(k) is defined in the main text; the set
of k points which satisfy the Hartree-Fock quasi-particle equation but fail to
satisfy S_{s}(k) = 0, constitute the pseudo-gap region of the putative Fermi
surface of the interacting system. We consider the behaviour of the
ground-state momentum-distribution function n_{s}(k) for k in the vicinity of
S_{F;s} and show that whereas for the uniform metallic ground states of the
conventional Hubbard Hamiltonian n_{s}(k) is greater/less than 0.5 for k
approaching S_{F;s} from inside/outside the Fermi sea, for interactions of
non-zero range these inequalities can be violated (without thereby contravening
the condition of the non-negativity of the possible jump in n_{s}(k) on k
crossing S_{F;s} from directly inside to directly outside the Fermi sea). We
discuss, in the light of the findings of the present work, the growing
experimental evidence with regard to the `frustration' of the kinetic energy of
the charge carriers in the normal states of the copper-oxide-based
high-temperature superconducting compounds. [Short abstract]Comment: 30 pages, 3 postscript figures. Brought into conformity with the
published versio
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