Geometry of Valley Growth

Although amphitheater-shaped valley heads can be cut by groundwater flows emerging from springs, recent geological evidence suggests that other processes may also produce similar features, thus confounding the interpretations of such valley heads on Earth and Mars. To better understand the origin of this topographic form we combine field observations, laboratory experiments, analysis of a high-resolution topographic map, and mathematical theory to quantitatively characterize a class of physical phenomena that produce amphitheater-shaped heads. The resulting geometric growth equation accurately predicts the shape of decimeter-wide channels in laboratory experiments, 100-meter wide valleys in Florida and Idaho, and kilometer wide valleys on Mars. We find that whenever the processes shaping a landscape favor the growth of sharply protruding features, channels develop amphitheater-shaped heads with an aspect ratio of pi

Recirculation cells in a wide channel

International audienceSecondary flow cells are commonly observed in straight laboratory channels, where they are often associated with duct corners. Here, we present velocity measurements acquired with an acoustic Doppler current profiler in a straight reach of the Seine river (France). We show that a remarkably regular series of stationary flow cells spans across the entire channel. They are arranged in pairs of counter-rotating vortices aligned with the primary flow. Their existence away from the river banks contradicts the usual interpretation of these secondary flow structures, which invokes the influence of boundaries. Based on these measurements, we use a depth-averaged model to evaluate the momentum transfer by these structures, and find that it is comparable with the classical turbulent transfer

Randomized controlled trial of rituximab and cost-effectiveness analysis in treating fatigue and oral dryness in primary Sjögren's Syndrome

Objective To investigate whether rituximab, an anti–B cell therapy, improves symptoms of fatigue and oral dryness in patients with primary Sjögren's syndrome (SS). Methods We conducted a multicenter, randomized, double‐blind, placebo‐controlled, parallel‐group trial that included health economic analysis. Anti‐Ro–positive patients with primary SS, symptomatic fatigue, and oral dryness were recruited from 25 UK rheumatology clinics from August 2011 to January 2014. Patients were centrally randomized to receive either intravenous (IV) placebo (250 ml saline) or IV rituximab (1,000 mg in 250 ml saline) in 2 courses at weeks 0, 2, 24, and 26, with pre‐ and postinfusion medication including corticosteroids. The primary end point was the proportion of patients achieving a 30% reduction in either fatigue or oral dryness at 48 weeks, as measured by visual analog scale. Other outcome measures included salivary and lacrimal flow rates, quality of life, scores on the European League Against Rheumatism (EULAR) Sjögren's Syndrome Patient Reported Index and EULAR Sjögren's Syndrome Disease Activity Index, symptoms of ocular and overall dryness, pain, globally assessed disease activity, and cost‐effectiveness. Results All 133 patients who were randomized to receive placebo (n = 66) or rituximab (n = 67) were included in the primary analysis. Among patients with complete data, 21 of 56 placebo‐treated patients and 24 of 61 rituximab‐treated patients achieved the primary end point. After multiple imputation of missing outcomes, response rates in the placebo and rituximab groups were 36.8% and 39.8%, respectively (adjusted odds ratio 1.13 [95% confidence interval 0.50, 2.55]). There were no significant improvements in any outcome measure except for unstimulated salivary flow. The mean ± SD costs per patient for rituximab and placebo were £10,752 ± 264.75 and £2,672 ± 241.71, respectively. There were slightly more adverse events (AEs) reported in total for rituximab, but there was no difference in serious AEs (10 in each group). Conclusion The results of this study indicate that rituximab is neither clinically effective nor cost‐effective in this patient population

Neurological Disorders in Primary Sjögren's Syndrome.

International audienceSjögren's syndrome is an autoimmune disease characterized by an autoimmune exocrinopathy involving mainly salivary and lacrimal glands. The histopathological hallmark is periductal lymphocytic infiltration of the exocrine glands, resulting in loss of their secretory function. Several systemic manifestations may be found in patients with Sjögren's syndrome including neurological disorders. Neurological involvement ranges from 0 to 70% among various series and may present with central nervous system and/or peripheral nervous system involvement. This paper endeavors to review the main clinical neurological manifestations in Sjögren syndrome, the physiopathology, and their therapeutic response

Path selection in the growth of rivers

River networks exhibit a complex ramified structure that has inspired decades of studies. However, an understanding of the propagation of a single stream remains elusive. Here we invoke a criterion for path selection from fracture mechanics and apply it to the growth of streams in a diffusion field. We show that, as it cuts through the landscape, a stream maintains a symmetric groundwater flow around its tip. The local flow conditions therefore determine the growth of the drainage network. We use this principle to reconstruct the history of a network and to find a growth law associated with it. Our results show that the deterministic growth of a single channel based on its local environment can be used to characterize the structure of river networks.United States. Department of Energy (Grant FG02-99ER15004

Atypical coordination of cortical oscillations in response to speech in autism.

Subjects with autism often show language difficulties, but it is unclear how they relate to neurophysiological anomalies of cortical speech processing. We used combined EEG and fMRI in 13 subjects with autism and 13 control participants and show that in autism, gamma and theta cortical activity do not engage synergistically in response to speech. Theta activity in left auditory cortex fails to track speech modulations, and to down-regulate gamma oscillations in the group with autism. This deficit predicts the severity of both verbal impairment and autism symptoms in the affected sample. Finally, we found that oscillation-based connectivity between auditory and other language cortices is altered in autism. These results suggest that the verbal disorder in autism could be associated with an altered balance of slow and fast auditory oscillations, and that this anomaly could compromise the mapping between sensory input and higher-level cognitive representations

Diagnostic accuracy of blood B-cell subset profiling and autoimmunity markers in Sjögren's syndrome.

International audienceThe aims of this study were to evaluate the diagnostic accuracy of blood B-cell subset profiling and immune-system activation marker assays in primary Sjögren's syndrome (pSS) and to assess whether adding these tools to the current laboratory item would improve the American-European Consensus Group (AECG) criteria. METHODS: In a single-center cohort of patients with suspected pSS, we tested the diagnostic performance of anti-SSA, antinuclear antibody (ANA), rheumatoid factor (RF), gammaglobulins, IgG titers, and B-cell ratio defined as (Bm2 + Bm2')/(eBm5 + Bm5), determined using flow cytometry. The reference standard was a clinical diagnosis of pSS established by a panel of experts. RESULTS: Of 181 patients included in the study, 77 had pSS. By logistic regression analysis, only ANA ≥1:640 (sensitivity, 70.4%; specificity 83.2%) and B-cell ratio ≥5 (sensitivity, 52.1%; specificity, 83.2%) showed independent associations with pSS of similar strength. In anti-SSA-negative patients, presence of either of these two criteria had 71.0% sensitivity but only 67.3% specificity for pSS; whereas combining both criteria had 96.2% specificity but only 12.9% sensitivity. Adding either of these two criteria to the AECG criteria set increased sensitivity from 83.1% to 90.9% but decreased specificity from 97.1% to 85.6%, whereas adding both criteria in combination did not substantially modify the diagnostic performance of the criteria set. The adjunction of RF + ANA ≥1:320, as proposed in the new American College of Rheumatology (ACR) criteria, did not improve the diagnostic value of anti-SSA. CONCLUSIONS: Blood B-cell subset profiling is a simple test that has good diagnostic properties for pSS. However, adding this test, with or without ANA positivity, does not improve current classification criteria

The ability of synovitis to predict structural damage in rheumatoid arthritis: A comparative study between clinical examination and ultrasound

Objectives: To evaluate synovitis (clinical vs ultrasound (US)) to predict structural progression in rheumatoid arthritis (RA). Methods: Patients with RA. Study design: Prospective, 2-year follow-up. Data collected: Synovitis (32 joints (2 wrists, 10 metacarpophalangeal, 10 proximal interphalangeal, 10 metatarsophalangeal)) at baseline and after 4 months of therapy by clinical, US grey scale (GS-US) and power doppler (PD-US); x-rays at baseline and at year 2. Analysis: Measures of association (OR) were tested between structural deterioration and the presence of baseline synovitis, or its persistence, after 4 months of therapy using generalised estimating equation analysis. Results: Structural deterioration was observed in 9% of the 1888 evaluated joints in 59 patients. Baseline synovitis increased the risk of structural progression: OR=2.01 (1.36-2.98) p<0.001 versus 1.61 (1.06-2.45) p=0.026 versus 1.75 (1.18-2.58) p=0.005 for the clinical versus US-GS versus US-PD evaluation, respectively. In the joints with normal baseline examination (clinical or US), an increased probability for structural progression in the presence of synovitis for the other modality was also observed (OR=2.16 (1.16-4.02) p=0.015 and 3.50 (1.77-6.95) p<0.001 for US-GS and US-PD and 2.79 (1.35-5.76) p=0.002) for clinical examination. Persistent (vs disappearance) synovitis after 4 months of therapy was also predictive of subsequent structural progression. Conclusions: This study confi rms the validity of synovitis for predicting subsequent structural deterioration irrespective of the modality of examination of joints, but also suggests that both clinical and ultrasonographic examinations may be relevant to optimally evaluate the risk of subsequent structural deterioration