15,861 research outputs found
Use of the painDETECT tool in rheumatoid arthritis suggests neuropathic and sensitization components in pain reporting.
Rheumatoid arthritis (RA) is an inflammatory autoimmune condition typified by systemic inflammation targeted toward synovial joints. Inhibition of proinflammatory networks by disease-modifying antirheumatic drugs, eg, methotrexate and biologic therapies, including tumor necrosis factor-α inhibitors, often leads to suppression of disease activity observed at the clinical level. However, despite the era of widespread use of disease-modifying treatments, there remain significant groups of patients who continue to experience pain. Our study formulated a pain assessment tool in the arthritis clinic to assess feasibility of measurements including the visual analog scale (VAS) and painDETECT to assess multimodal features of pain in people with established RA (n=100). Clinical measures of disease activity (Disease Activity Score in 28 Joints [DAS28]) were also recorded. Our data showed that despite the majority of subjects on at least one disease-modifying agent, the majority of patients reported severe pain (54%) by VAS, despite well-controlled clinical disease, with mean DAS28 2.07±0.9. Using the painDETECT questionnaire, 67% of patients had unlikely neuropathic pain. A significant proportion of subjects (28%) had possible neuropathic pain and 5% had features of likely neuropathic pain by painDETECT scoring. We found a positive correlation between VAS and painDETECT (R (2)=0.757). Of note, the group who had likely or probable neuropathic pain also showed significantly increased pain reporting by VAS (P30) also had statistically higher proportions of pain reporting (VAS 89.0±0.7 mm) compared with subjects who had a normal body mass index (VAS 45.2±21.8 mm), P<0.05. Our findings suggest that multimodal features of pain perception exist in RA, including neuropathic and sensitization elements, perhaps explaining why a subgroup of people with RA continue to experience ongoing pain, despite their apparent suppression of inflammation
The Distribution of Alpha Elements in Ultra-Faint Dwarf Galaxies
The Milky Way ultra-faint dwarf galaxies (UFDs) contain some of the oldest,
most metal-poor stars in the Universe. We present [Mg/Fe], [Si/Fe], [Ca/Fe],
[Ti/Fe], and mean [alpha/Fe], abundance ratios for 61 individual red giant
branch stars across 8 UFDs. This is the largest sample of alpha abundances
published to date in galaxies with absolute magnitudes M_V > -8, including the
first measurements for Segue 1, Canes Venatici II, Ursa Major I, and Leo T.
Abundances were determined via medium-resolution Keck/DEIMOS spectroscopy and
spectral synthesis. The sample spans the metallicity range -3.4 < [Fe/H] <
-1.1. With the possible exception of Segue 1 and Ursa Major II, the individual
UFDs show on average lower [alpha/Fe] at higher metallicities, consistent with
enrichment from Type Ia supernovae. Thus even the faintest galaxies have
undergone at least a limited level of chemical self-enrichment. Together with
recent photometric studies, this suggests that star formation in the UFDs was
not a single burst, but instead lasted at least as much as the minimum time
delay of the onset of Type Ia supernovae (~100 Myr) and less than ~2 Gyr. We
further show that the combined population of UFDs has an [alpha/Fe] abundance
pattern that is inconsistent with a flat, Galactic halo-like alpha abundance
trend, and is also qualitatively different from that of the more luminous CVn I
dSph, which does show a hint of a plateau at very low [Fe/H].Comment: 14 pages, 6 figures, re-submitted to ApJ with revisions based on
referee repor
Metastable states influence on the magnetic behavior of the triangular lattice: Application to the spin-chain compound Ca3Co2O6
It is known that the spin-chain compound Ca3Co2O6 exhibits very interesting
plateaus in the magnetization as a function of the magnetic field at low
temperatures. The origin of them is still controversial. In this paper we study
the thermal behavior of this compound with a single-flip Monte Carlo simulation
on a triangular lattice and demonstrate the decisive influence of metastable
states in the splitting of the ferrimagnetic 1/3 plateau below 10 K. We
consider the [Co2O6]n chains as giant magnetic moments described by large Ising
spins on planar clusters with open boundary conditions. With this simple
frozen-moment model we obtain stepped magnetization curves which agree quite
well with the experimental results for different sweeping rates. We describe
particularly the out-of-equilibrium states that split the low-temperature 1/3
plateau into three steps. They relax thermally to the 1/3 plateau, which has
long-range order at the equilibrium. Such states are further analyzed with
snapshots unveiling a domain-wall structure that is responsible for the
observed behavior of the 1/3 plateau. A comparison is also given of the exact
results in small triangular clusters with our Monte Carlo results, providing
further support for our thermal description of this compound.Comment: 8 pages, 11 figures, submitted to PR
Isoskeletal Schiff base polynuclear coordination clusters: synthetic and theoretical aspects
This work addresses and enlightens synthetic aspects derived from our effort to systematically construct isoskeletal tetranuclear coordination clusters (CCs) of the general formula [TR2Ln2(LX)4(NO3)2(solv)2] possessing a specific defected dicubane topology, utilizing various substituted Schiff base organic ligands (H2LX) and NiII/CoII and Dy(OTf)3 salts. Our synthetic work is further supported by DFT studies
Kinetics and thermodynamics of the reversible solvation of 2, 3-butanedione
En este trabajo se realiza un estudio de la adición reversible de agua y metanol a 2 ,3-butanodiona. Los valores de ΛH y ΛS de adición de agua y metanol son muy similares. Al diluir los solventes próticos con acetona se observa una marcada disminución en la exotermicidad de la adición. A pesar de la similitud en los parámetros termodinámicos, la hidratación es un proceso mucho más rápido que la adición de metanol
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