Brownian motion meets Riemann curvature

The general covariance of the diffusion equation is exploited in order to explore the curvature effects appearing on brownian motion over a d-dimensional curved manifold. We use the local frame defined by the so called Riemann normal coordinates to derive a general formula for the mean-square geodesic distance (MSD) at the short-time regime. This formula is written in terms of $O(d)$ invariants that depend on the Riemann curvature tensor. We study the n-dimensional sphere case to validate these results. We also show that the diffusion for positive constant curvature is slower than the diffusion in a plane space, while the diffusion for negative constant curvature turns out to be faster. Finally the two-dimensional case is emphasized, as it is relevant for the single particle diffusion on biomembranes.Comment: 16 pages and 3 figure

An Empirical Examination of Symptom Substitution Associated with Behavior Therapy for Tourette\u27s Disorder

Over the past six decades, behavior therapy has been a major contributor to the development of evidence-based psychotherapy treatments. However, a long-standing concern with behavior therapy among many nonbehavioral clinicians has been the potential risk for symptom substitution. Few studies have been conducted to evaluate symptom substitution in response to behavioral treatments, largely due to measurement and definitional challenges associated with treated psychiatric symptoms. Given the overt motor and vocal tics associated with Tourette’s disorder, it presents an excellent opportunity to empirically evaluate the potential risk for symptom substitution associated with behavior therapy. The present study examined the possible presence of symptom substitution using four methods: (a) the onset of new tic symptoms, (b) the occurrence of adverse events, (c) change in tic medications, and (d) worsening of co-occurring psychiatric symptoms. Two hundred twenty-eight participants with Tourette’s disorder or persistent motor or vocal tic disorders were randomly assigned to receive behavioral therapy or supportive therapy for tics. Both therapies consisted of eight sessions over 10 weeks. Results indicated that participants treated with behavior therapy were not more likely to have an onset of new tic symptoms, experience adverse events, increase tic medications, or have an exacerbation in co-occurring psychiatric symptoms relative to participants treated with supportive therapy. Further analysis suggested that the emergence of new tics was attributed with the normal waxing and waning nature of Tourette’s disorder. Findings provide empirical support to counter the long-standing concern of symptom substitution in response to behavior therapy for individuals with Tourette\u27s disorder

A Silvopastoral System in the North Atlantic Zone of Costa Rica: Combining Indigenous Timber Species with Dairy Pasture Swards

The objective of this study was to design, establish and monitor a silvo pastoral experiment on a dairy farm in the northern Atlantic region of Costa Rica. Indigenous timber species, Vochysia guatemalensis and Hyeronima alchorneoides were used together with or without the tropical pasture legume, Arachis pintoi in a split plot design with a 4 x 2 x 2 factorial arrangement. First year establishment was good for the tree component (2.3 to 10 % mortality) but poor for A. pintoi (4 to 5 % of sward). Poor legume establishment was attributed to lax grazing management and excess competition from existing Brachiaria sp. A. Pintoi was reestablished in July 1996 after an adjustment of stocking rate. This experimental project is planned for a 10 year period which corresponds to the expected rotation length for harvesting the indigenous timber species

Generally covariant state-dependent diffusion

Statistical invariance of Wiener increments under SO(n) rotations provides a notion of gauge transformation of state-dependent Brownian motion. We show that the stochastic dynamics of non gauge-invariant systems is not unambiguously defined. They typically do not relax to equilibrium steady states even in the absence of extenal forces. Assuming both coordinate covariance and gauge invariance, we derive a second-order Langevin equation with state-dependent diffusion matrix and vanishing environmental forces. It differs from previous proposals but nevertheless entails the Einstein relation, a Maxwellian conditional steady state for the velocities, and the equipartition theorem. The over-damping limit leads to a stochastic differential equation in state space that cannot be interpreted as a pure differential (Ito, Stratonovich or else). At odds with the latter interpretations, the corresponding Fokker-Planck equation admits an equilibrium steady state; a detailed comparison with other theories of state-dependent diffusion is carried out. We propose this as a theory of diffusion in a heat bath with varying temperature. Besides equilibrium, a crucial experimental signature is the non-uniform steady spatial distribution.Comment: 24 page

How expensive is treating patients in a center of excellence for rheumatoid arthritis in Colombia?

We aimed to estimate the cost of treating patients with rheumatoid arthritis (RA) in a Center of Excellence (CoE) for rheumatic diseases located in Bogotá, Colombia. We performed a cost analysis from the standard cost estimation of a CoE program for RA care. We estimated costs of consultations, laboratory and imaging tests, and pharmacological treatment from the measurement of the health care resource utilization of the CoE standard protocol according to the activity level of the disease (DAS28). Costing process was done following the recommendation of the Colombian Institute of Health Technology Assessment (IETS, in Spanish). Mean, minimum and maximum costs were reported annually for a type case depending on severity and classified as Remission, low disease activity (LDA), moderate disease activity (MDA) and severe disease activity -SDA- (with and without bDMARD). All costs were reported in American dollars, using the average exchange rate from January to December of 2018, reported by Banco de la República de Colombia: US$1 =$2,951.3 Colombian pesos. Mean total direct medical cost to treat a patient in remission is US$235.7 (213.0-336.4), in LDA is US325.2 (288.0-464.6) and in MDA is US$835.5 ($573.1-$2,187.1). There is a considerable increase in direct medical costs from a patient in SDA and SDA+Biologics: US$2,555.5 ($2,301.1-$3,890.9) to US$8,032.4 ($7,564.4-$8,400.3). The largest share of the cost was related to drugs, representing 39.9% for Remission, 53.6% for LDA, 75.2 for MDA, and in SDA and SDA+Biologics the proportion of what is spent on drugs for RA treatment is 88.5% and 96.7%, respectively. As the severity of the disease increases, the expenditure rate on drugs rises over the total of each activity level. With the introduction of the biological therapy, the treatment of RA is expensive, however, the CoE is an efficient way of care for RA

Quality of life and the relationship with family income in patients with rheumatoid arthritis

Objectives: To evaluate the quality of life (QoL) of patients with rheumatoid arthritis (RA) using the Quality of life in Rheumatoid Arthritis (RAQol) questionnaire. Also, to explore its relationship with income in patients attended at a specialized RA center in Bogotá, Colombia, 2018. Methods: We performed a descriptive study. The RAQol version in Spanish was applied to RA patients. The scale of the RAQol has a score from 1-10, where 10 is associated with better QoL. We excluded patients with psychological or psychiatric disorders. We asked about the monthly family income according to the Colombian minimum wage. Descriptive epidemiology was performed for each variable. A comparison of means regarding age and RAQol score was carried out. Therefore, we performed a bivariate analysis in order to explore the relationship between income and QoL, reporting Odds Ratios (OR) and confidence intervals 95% (CI95%). Results related to family income were reported in US$with the average exchange rate for 2018. Results: We interviewed 310 patients, 92$265, 47% between US$266- US$530, 9% between US$531-US$795 and 3% more than US$1300. Patients with an income greater than US$531 per/month had a higher average score in the RAQoL scale (7.1, SD5.5). The relationship of having a score lower than 6 in the RAQoL and a monthly income lower than US$530 showed an OR of 2.48 IC95% (0.99-6.22) (P=0.03). Conclusions: Our study showed that patient with a low income reports a lower QoL. Further research is needed to evaluate the alternatives that can improve QoL in patients with RA

Costs and disease activity in patients with rheumatoid arthritis treated with biologic dmards: findings in a real-life setting

Objectives: Biological DMARDs have demonstrated to modify the natural course of the disease through the inhibition of specific molecules of the immune and inflammatory responses. The objective of our study is to describe the use of biological therapy, disease activity and costs related to the treatment of patients with RA in a real-life setting in Colombia. Methods: Patients were analyzed retrospectively for 36 months and followed-up under T2T standards with a multidisciplinary approach. DAS28 was used as main clinical outcome. We included patients with severe or moderate disease activity using biological therapy. We described the percentage of patients who reached low disease activity or remission. Most expensive biological therapies were described and costed. Costs were reported in US dollars at the official rate of exchange for December 2018. Statistical analyses were done in Microsoft Excel. Results: We followed-up 1054 patients during three years, 85% were female, mean age was 57 years (SD 7.7). At the beginning of the follow-up, 52% of patients were in MDA and 48% in SDA. The most used treatment regime was certolizumab (24.57%) followed by etanercept (16.51%) and abatacept (12.81%). At the end of the follow-up, 92% patients achieved remission. Regarding costs, the most expensive therapy per/ year was etanercept (USD $12,522.70) followed by golimumab ($11,535.00) and (adalimumab). When we calculated the average cost for all biological therapy and then compared to the number of patients who achieved remission, the costs during three years to achieve remission was $27,738,839.54 USD. Conclusions: Our study showed that biological therapy is effective when is used under a T2T strategy and with a multidisciplinary approach. However, it is an expensive option that might be used in adherent patients and candidates who met the profile for prescribing this type of pharmacological therapy, especially in developing countries where the health budgets are limited

Nueva especie de Mastigoproctus Pocock, 1894 (Thelyphonida, Thelyphonidae) de Venezuela noroccidental

A new species of the genus Mastigoproctus Pocock, 1894 is described from Falcon state in northwestern Venezuela. This is the third Mastigoproctus species recorded for this country, the northernmost record of the genus in South America and the first record of the order for Falcon state.Una nueva especie del género Mastigoproctus Pocock, 1894 es descrita para el estado Falcón, en el tramo occidental de la Cordillera de la Costa, Venezuela. Es la tercera especie del género registrada para el país, siendo el registro más al norte del género en el continente suramericano y el primero del orden para el estado Falcón