138 research outputs found
Thermal Conductivity of Neutrons in Neutron Star Cores
The diffusive thermal conductivity of neutrons in dense matter [ g cm] of neutron star cores is calculated. The
contribution from neutron--neutron and neutron--proton collisions is taken into
account. We use the transition probabilities calculated for symmetric dense
nucleon matter on the basis of the Dirac--Brueckner approach to the in-medium
effects and the Bonn model of bare nucleon--nucleon interaction. The diffusive
thermal conductivity of neutrons in the presence of neutron and proton
superfluidities is analyzed in a microscopic manner; the effects of
superfluidity are shown to be significant. The low temperature behavior of the
thermal conductivity appears to be extremely sensitive to the relation between
critical temperatures of neutrons and protons. The results are fitted by simple
analytic expressions. In combination with the formulae for the electron and
muon thermal conductivities, obtained earlier, the present expressions provide
a realistic description of the full diffusive thermal conductivity in the
neutron star cores for normal and various superfluid phases.Comment: 13 pages, 4 figures, accepted to A
Antibodies to infliximab and adalimumab in patients with rheumatoid arthritis in clinical remission:a cross-sectional study
Objective. To investigate if antibodies towards biological TNF-Îą inhibitors (anti-TNFi Abs) are present in patients with rheumatoid arthritis (RA) in clinical remission and to relate any anti-TNFi Abs to circulating level of TNF-Îą inhibitor (TNFi). Methods. Patients with RA, treated with infliximab or adalimumab, and in clinical remission (DAS28(CRP) < 2.6) were included from 6 out-patient clinics. In blood samples, presence of anti-TNFi Abs was determined by radioimmunoassay, and concentration of bioactive TNFi was measured by a cell-based reporter gene assay. Results. Anti-TNFi Abs were present in 8/44 patients (18%) treated with infliximab and 1/49 patients (2%) treated with adalimumab (p=0.012). In the former group, anti-TNFi Abs corresponded with low levels of TNFi (p=0.048). Anti-TNFi Ab-positive patients had shorter disease duration at initiation of TNFi therapy (p=0.023) but were similar for the rest of the compared parameters. Conclusions. In RA patients in clinical remission, anti-TNFi Abs occur frequently in patients treated with infliximab, while they occur rarely in patients treated with adalimumab. Presence of anti-infliximab Abs is accompanied by low or undetectable levels of infliximab. These data suggest that continued infliximab treatment may be redundant in a proportion of RA patients treated with infliximab and in clinical remission
Strongly nonlinear dynamics of electrolytes in large ac voltages
We study the response of a model micro-electrochemical cell to a large ac
voltage of frequency comparable to the inverse cell relaxation time. To bring
out the basic physics, we consider the simplest possible model of a symmetric
binary electrolyte confined between parallel-plate blocking electrodes,
ignoring any transverse instability or fluid flow. We analyze the resulting
one-dimensional problem by matched asymptotic expansions in the limit of thin
double layers and extend previous work into the strongly nonlinear regime,
which is characterized by two novel features - significant salt depletion in
the electrolyte near the electrodes and, at very large voltage, the breakdown
of the quasi-equilibrium structure of the double layers. The former leads to
the prediction of "ac capacitive desalination", since there is a time-averaged
transfer of salt from the bulk to the double layers, via oscillating diffusion
layers. The latter is associated with transient diffusion limitation, which
drives the formation and collapse of space-charge layers, even in the absence
of any net Faradaic current through the cell. We also predict that steric
effects of finite ion sizes (going beyond dilute solution theory) act to
suppress the strongly nonlinear regime in the limit of concentrated
electrolytes, ionic liquids and molten salts. Beyond the model problem, our
reduced equations for thin double layers, based on uniformly valid matched
asymptotic expansions, provide a useful mathematical framework to describe
additional nonlinear responses to large ac voltages, such as Faradaic
reactions, electro-osmotic instabilities, and induced-charge electrokinetic
phenomena.Comment: 30 pages, 17 eps-figures, RevTe
Measurement properties of radiographic outcome measures in Psoriatic Arthritis:A systematic review from the GRAPPA-OMERACT initiative
Background
Structural damage is as an important outcome in the Psoriatic Arthritis (PsA) Core Domain Set and its assessment is recommended at least once in the development of a new drug.
Objectives
To conduct a systematic review (SR) to identify studies addressing the measurement properties of radiographic outcome instruments for structural damage in PsA and appraise the evidence through the Outcome Measures in Rheumatology (OMERACT) Filter 2.1 Framework Instrument Selection Algorithm (OFISA).
Methods
A SR was conducted using search strategies in EMBASE and MEDLINE to identify full-text English studies which aimed to develop or assess the measurement properties of radiographic outcome instruments in PsA. Determination of eligibility and data extraction was performed independently by two reviewers with input from a third to achieve consensus. Two reviewers assessed the methodology and results of eligible studies and synthesized the evidence using OMERACT methodology.
Results
Twelve articles evaluating radiographic instruments were included. The articles assessed nine peripheral (hands, wrists and/or feet) and six axial (spinal and/or sacroiliac joints) radiographic instruments. The peripheral radiographic instruments with some evidence for reliability, cross-sectional construct validity and longitudinal construct validity were the Ratingen and modified Sharp van der Heijde scores. No instruments had evidence for clinical trial discrimination or thresholds of meaning. There was limited evidence for the measurement properties of all identified axial instruments.
Conclusion
There are significant knowledge gaps in the responsiveness of peripheral radiographic instruments. Axial radiographic instruments require further validation, and the need to generate novel instruments and utilise other imaging modalities should be considered
Evaluating standards of care in psoriatic arthritis of the QUANTUM project (qualitative initiative to improve outcomes): results of an accreditation project in Spain
In Spain, the QUANTUM project has been promoted to reduce variability in clinical practice and improve the care and quality of life of people with psoriatic arthritis (PsA) by accrediting PsA units throughout the Spanish national health system. To present the results of this approach which sought to ensure an optimum level of quality for patients with PsA. Descriptive analysis of the self-assessments that the PsA units have carried out assessing their degree of compliance with the quality standards established in the QUANTUM project grouped into four blocks: shortening time to diagnosis; optimizing disease management; improving multidisciplinary collaboration; and improving patient monitoring. A total of 41 PsA units were self-evaluated. They met 64.1% of the defined quality standards. Optimize disease management obtained a higher level of standards compliance (72%) and improve multidisciplinary collaboration the lesser (63.9%). Accessibility to the treatments available for PsA in all hospitals was guaranteed (100%). Appropriate diagnostic equipment is available (97.6%). Compliance with specific quality standards leads to detect actions that should be implemented: quality of life assessment (9.8%), locomotor system assessment (12.2%), physical examination data record (14.6%), periodic cardiovascular risk assessment (17.1%). The QUANTUM project results make it possible to visualise how to care for patients with PsA is being developed in Spain. Problems identified in recent multinational reports are also identified in Spain
A systematic review of measurement properties of patient reported outcome measures in psoriatic arthritis: A GRAPPA-OMERACT initiative
Background: An updated psoriatic arthritis (PsA) core outcome set (COS) for randomized controlled trials (RCTs) was endorsed at the Outcome Measures in Rheumatology (OMERACT) meeting in 2016. Objectives: To synthesize the evidence on measurement properties of patient reported outcome measures (PROMs) for PsA and thereby contribute to development of a PsA core outcome measurement set (COMS) as described by the OMERACT Filter 2.0. Methods: A systematic literature search was performed in EMBASE, MEDLINE and PsycINFO on Jan 1, 2017 to identify full-text articles with an aim of assessing the measurement properties of PROMs in PsA. Two independent reviewers rated the quality of studies using the COnsensus based standards for the Selection of health Measurement INstruments (COSMIN) checklist, and performed a qualitative evidence synthesis. Results: Fifty-five studies were included in the systematic review. Forty-four instruments and a total of 89 scales were analyzed. PROMs measuring COS domains with at least fair quality evidence for good validity and reliability (and no evidence for poor properties) included the Stockerau Activity Score for PsA (German), Psoriasis Symptom Inventory, visual analogue scale for Patient Global, 36 Item Short Form Health Survey Physical Function subscale, Health Assessment Questionnaire Disability Index, Bath Ankylosing Spondylitis Functional Index, PsA Impact of Disease questionnaire, PsA Quality of Life questionnaire, VITACORA-19, Functional Assessment of Chronic Illness Therapy Fatigue scale and Social Role Participation Questionnaire. Conclusions: At least one PROM with some evidence for aspects of validity and reliability was available for six of the eight mandatory domains of the PsA COS
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