Stakeholder-Driven Design Evolution of the Leveraged Freedom Chair Developing World Wheelchair

The Leveraged Freedom Chair (LFC) is a low-cost, all-terrain, variable mechanical advantage, lever-propelled wheelchair designed for use in developing countries. The user effectively changes gear by shifting his hands along the levers; grasping near the ends increases torque delivered to the drive-train, while grasping near the pivots enables a larger angular displacement with every stroke, which increases angular velocity in the drivetrain and makes the chair go faster. This paper chronicles the design evolution of the LFC through three user trials in East Africa, Guatemala, and India. Feedback from test subjects was used to refine the chair between trials, resulting in a device 9.1 kg (20 lbs) lighter, 8.9 cm (3.5 in) narrower, and with a center of gravity 12.7 cm (5 in) lower than the first iteration. Survey data substantiated increases in performance after successive iterations. Quantitative biomechanical performance data were also measured during the Guatemala and India trials, which showed the LFC to be 76 percent faster and 41 percent more efficient during a common daily commute and able to produce 51 percent higher peak propulsion force compared to conventional, pushrim-propelled wheelchairs

Symptoms of Raynaud's phenomenon (RP) in fibromyalgia syndrome are similar to those reported in primary RP despite differences in objective assessment of digital microvascular function and morphology

Symptoms of Raynaud’s phenomenon (RP) are common in fibromyalgia syndrome (FMS). We compared symptom characteristics and objective assessment of digital microvascular function using infrared thermography (and nailfold capillaroscopy where available) in patients with FMS (reporting RP symptoms) and primary RP. We retrospectively reviewed the outcome of microvascular imaging studies and RP symptom characteristics (captured using patient-completed questionnaire at the time of assessment) for patients with FMS (reporting RP symptoms) and patients with primary RP referred for thermographic assessment of RP symptoms over a 2-year period. Of 257 patients referred for thermographic assessment of RP symptoms between 2010 and 2012, we identified 85 patients with primary RP and 43 patients with FMS. There were no differences in RP symptom characteristics between FMS and primary RP (p > 0.05 for all comparisons). In contrast, patients with FMS had higher baseline temperature of the digits (32.1 vs. 29.0 °C, p = 0.004), dorsum (31.9 vs. 30.2 °C, p = 0.005) and thermal gradient (temperature of digits minus temperature of dorsum; +0.0 vs. −0.9 °C, p = 0.03) compared with primary RP. Significant differences between groups persisted following local cold challenge. In primary RP, patient reporting “blue” digits, bi-phasic and tri-phasic RP was associated with lower digital perfusion. In contrast, no associations between skin temperature and RP digital colour changes/phases were identified in FMS. Our findings suggest that symptoms of RP in FMS may have a different aetiology to those seen in primary RP. These findings have potential implications for both the classification of RP symptoms and the management of RP symptoms in the context of FMS. Digital colour changes reported by patients might reflect the degree of digital microvascular compromise in primary RP

A curvilinear search using tridiagonal secant updates for unconstrained optimization

The idea of doing a curvilinear search along the Levenberg- Marquardt path s(μ) = - (H + μI)⁻¹g always has been appealing, but the cost of solving a linear system for each trial value of the parameter y has discouraged its implementation. In this paper, an algorithm for searching along a path which includes s(μ) is studied. The algorithm uses a special inexpensive QTcQT to QT₊QT Hessian update which trivializes the linear algebra required to compute s(μ). This update is based on earlier work of Dennis-Marwil and Martinez on least-change secant updates of matrix factors. The new algorithm is shown to be local and q-superlinearily convergent to stationary points, and to be globally q-superlinearily convergent for quasi-convex functions. Computational tests are given that show the new algorithm to be robust and efficient.Facultad de Ciencias Exacta

Mortalidad y recurrencia de la enfermedad tromboembólica venosa en pacientes adultos: cohorte prospectiva

INTRODUCCIÓN: La enfermedad tromboembólica venosa (ETV) es una patología que aumenta con la edad. Objetivo: comparar la sobrevida de los ancianos y los jóvenes con un primer episodio de ETV aguda y sintomática. MATERIALES Y MÉTODOS: Cohorte prospectiva de casos incidentes de ETV incluidos en el Registro Institucional de Enfermedad Tromboembólica venosa (NCT01372514) del Hospital Italiano de Buenos Aires entre 2012-2014, dividido en grupos jóvenes (17-64 años) y ancianos (≥ 65 años). Todos los pacientes fueron seguidos anualmente para evaluar el tiempo a la recurrencia (progresión o nuevo evento sintomático de ETV) como eventos competitivos en contexto de muerte y sangrado mayor. Se presentaron los riesgos crudos (c) y ajustados (a). RESULTADOS: se incluyeron 446 pacientes, el 63% (292) fueron mayores de 65 años. La sobrevida fue menor en los ancianos comparados con los jóvenes (p 0.007), a los 3 meses 87% vs 95% y al año 73% vs 87%, respectivamente. Los ancianos presentaron un HRc1,71 y HR a 1.68. La recurrencia global fue 5% (IC 95% 3-8) al mes, 6% (IC 95% 4-9) a los 3 meses, 8% (IC 95% 6-11) al año y 13% (IC 95% 9-18) a los dos años. No se encontró asociación entre la edad y la recurrencia sub hazard 0.8(IC 0,34-1,86). El sangrado ocurrió en un 9% (39) de los pacientes. CONCLUSIONES: La mortalidad global en pacientes con ETV confirmada es mayor en la población anciana. No hubo diferencias en relación a la recurrencia de ETV, ni el sangrado y tampoco con la edad

Patient-reported outcome instruments for assessing Raynaud’s phenomenon in systemic sclerosis:A SCTC vascular working group report

The episodic nature of Raynaud’s phenomenon in systemic sclerosis has led to a reliance on patient-reported outcome instruments such as the Raynaud’s Condition Score diary. Little is known about the utilization in routine clinical practice and health professional attitudes toward existing patient-reported outcome instruments for assessing systemic sclerosis- Raynaud’s phenomenon. Members of the Scleroderma Clinical Trials Consortium Vascular Working Group (n = 28) were invited to participate in a survey gauging attitudes toward the Raynaud’s Condition Score diary and the perceived need for novel patient-reported outcome instruments for assessing patient-reported outcome. Nineteen Scleroderma Clinical Trials Consortium Vascular Working Group members (68% response rate) from academic units based in North America (n = 9), Europe (n = 8), South America (n = 1) and Australasia (n = 1) took part in the survey. There was broad consensus that Raynaud’s Condition Score diary returns could be influenced by factors including seasonal variation in weather, efforts made by patients to avoid or ameliorate attacks of Raynaud’s phenomenon, habituation to Raynaud’s phenomenon symptoms, evolution of Raynaud’s phenomenon symptom characteristics with progressive obliterative microangiopathy, patient-coping strategies, respondent burden and placebo effect. There was consensus that limitations of the Raynaud’s Condition Score diary might be a barrier to drug development (79% of respondents agree/strongly agree) and that a novel patient-reported outcome instrument for assessing systemic sclerosis-Raynaud’s phenomenon should be developed with the input of both clinicians and patients (84% agree/strongly agree). Perceived potential limitations of the Raynaud’s Condition Score diary have been identified along with concerns that such factors might impede drug development programs for systemic sclerosis-Raynaud’s phenomenon. There is support within the systemic sclerosis community for the development of a novel patient-reported outcome instrument for assessing systemic sclerosis-Raynaud’s phenomenon.</p

Efficient Reconstruction of Metabolic Pathways by Bidirectional Chemical Search

One of the main challenges in systems biology is the establishment of the metabolome: a catalogue of the metabolites and biochemical reactions present in a specific organism. Current knowledge of biochemical pathways as stored in public databases such as KEGG, is based on carefully curated genomic evidence for the presence of specific metabolites and enzymes that activate particular biochemical reactions. In this paper, we present an efficient method to build a substantial portion of the artificial chemistry defined by the metabolites and biochemical reactions in a given metabolic pathway, which is based on bidirectional chemical search. Computational results on the pathways stored in KEGG reveal novel biochemical pathways