Learning Parities in the Mistake-Bound model

We study the problem of learning parity functions that depend on at most $k$ variables ($k$-parities) attribute-efficiently in the mistake-bound model. We design a simple, deterministic, polynomial-time algorithm for learning $k$-parities with mistake bound $O(n^{1-frac{c}{k}})$, for any constant $c > 0$. This is the first polynomial-time algorithms that learns $omega(1)$-parities in the mistake-bound model with mistake bound $o(n)$. Using the standard conversion techniques from the mistake-bound model to the PAC model, our algorithm can also be used for learning $k$-parities in the PAC model. In particular, this implies a slight improvement on the results of Klivans and Servedio cite{rocco} for learning $k$-parities in the PAC model. We also show that the $widetilde{O}(n^{k/2})$ time algorithm from cite{rocco} that PAC-learns $k$-parities with optimal sample complexity can be extended to the mistake-bound model

Validation of Matching

We introduce a technique to compute probably approximately correct (PAC) bounds on precision and recall for matching algorithms. The bounds require some verified matches, but those matches may be used to develop the algorithms. The bounds can be applied to network reconciliation or entity resolution algorithms, which identify nodes in different networks or values in a data set that correspond to the same entity. For network reconciliation, the bounds do not require knowledge of the network generation process

Haemoparasites in endemic and non-endemic passerine birds from central Mexico highlands

Haemosporidian parasites of birds are found worldwide and include the genera Haemoproteus, Plasmodium and Leucocytozoon. Infection with haemosporidian parasites can affect host physical condition and reproductive success. The aim of this study was to identify the blood parasites and parasitaemia in endemic and non-endemic passerine birds from central Mexico highlands. This study included 157 passerines representing 29 species from 17 families. Overall, 30.6% (48/157) of the birds were infected with blood parasites. Of those, Haemoproteus spp. were found in 14.0% (n = 22), Leucocytozoon spp. 12.1% (n = 19) and microfilariae 0.6% (n = 1). Blood parasites were found in 71.4% (5/7) of endemic bird species and 45.4% (10/22) of non-endemic species. Medium to high parasitaemia (number of parasites/number erythrocytes) was observed in birds with infections of Haemoproteus spp. and Leucocytozoon spp. Co-infections 3.8% (n = 6) were observed in two species of endemic birds. This study contributes to the knowledge of haemoparasites in endemic and non-endemic passerine birds from central Mexico highlands. Additional investigation on the molecular identification of haemosporidian parasites, pathogenicity and health status of these birds is necessary

Efficacy of a dilemma-focused intervention for unipolar depression : study protocol for a multicenter randomized controlled trial

This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly citedDepression is one of the more severe and serious health problems because of its morbidity, disabling effects and for its societal and economic burden. Despite the variety of existing pharmacological and psychological treatments, most of the cases evolve with only partial remission, relapse and recurrence. Cognitive models have contributed significantly to the understanding of unipolar depression and its psychological treatment. However, success is only partial and many authors affirm the need to improve those models and also the treatment programs derived from them. One of the issues that requires further elaboration is the difficulty these patients experience in responding to treatment and in maintaining therapeutic gains across time without relapse or recurrence. Our research group has been working on the notion of cognitive conflict viewed as personal dilemmas according to personal construct theory. We use a novel method for identifying those conflicts using the repertory grid technique (RGT). Preliminary results with depressive patients show that about 90% of them have one or more of those conflicts. This fact might explain the blockage and the difficult progress of these patients, especially the more severe and/or chronic. These results justify the need for specific interventions focused on the resolution of these internal conflicts. This study aims to empirically test the hypothesis that an intervention focused on the dilemma(s) specifically detected for each patient will enhance the efficacy of cognitive behavioral therapy (CBT) for depressionPeer reviewe

Tomografía computarizada a nivel de C3 y dinamometría como técnicas de diagnóstico de sarcopenia en pacientes con cáncer de cabeza y cuello

Introduction: A pilot study that tried to diagnosis sarcopenia by computed tomography (CT) at the third cervical vertebra (C3) and dynamometry in head and neck cancer patients. Comparison of the muscle mass (MM) determined by CT, with classical anthropometric measure and dynamometry techniques.Material and methods: MM and adipose tissue were analyzed by CT at C3 level in 37 oncological patients using Hounsfield Units (HU). Consequently, skeletal muscle index (SMI) and handgrip was determined for the diagnosis of sarcopenia. Finally, SMI was compared by classical anthropometric techniques, as well as by dynamometry.Results: 59.46% of the sample presented a decreased SMI (cm2/m2), 64.86% dynapenia, 54.05% sarcopenia, and 32.43% sarcopenic obesity. On the other hand, mean intermuscular adipose tissue was 6.69 (3.8) cm2, and mean intramuscular adipose tissue 2.06 (1.11) cm2.  In addition, a statistically significant association was found between SMI and strength in strong hand (estimate = 0.412, 95% CI [0.219, 0.605], p-value <0.001) and in the weak hand (estimate = 0.289, IC95% [0.123, 0.454], p-value <0.001). Regarding the branchial muscle circumference, we did not reach to demonstrate a positive correlation.Conclusions: Our study indicates that in head and neck cancer patients there is a high prevalence of sarcopenia. In addition, muscle depletion assessed by CT scans and dynamometry have demonstrate positive correlation, and consequently, those patients with greater muscle depletion at the C3 level have less muscle functionality.Introducción: Estudio piloto que determina el diagnóstico de sarcopenia mediante tomografía computarizada (TC) a nivel de la tercera vértebra cervical (C3) y dinamometría en pacientes con cáncer de cabeza y cuello. Comparación de la masa magra (MM) determinada mediante TC con técnicas clásicas de antropometría y dinamometría.Material y métodos: Se analizó la MM y el tejido adiposo mediante TC a nivel de C3 en 37 pacientes oncológicos mediante Unidades Hounsfield (UH). Posteriormente, se calculó el índice musculoesquelético (IME) y se determinó la fuerza prensora de mano para la determinación de sarcopenia. Por último, se comparó el IME mediante técnicas de valoración antropométrica clásica y dinamometría. Resultados: El 59,46% de los pacientes presentaron un IME (cm2/m2) disminuido, el 64,86% dinapenia, el 54,05% sarcopenia, el 32,43% sarcopenia dentro del sobrepeso y obesidad.  Por otro lado, la media de la masa grasa intermuscular fue 6,69 (3,8) cm2, y la masa grasa intramuscular 2,06 (1,11) cm2. Además, se encontró una asociación estadísticamente significativa entre la fuerza tanto en la mano fuerte (estimado = 0,412, IC95% [0,219; 0,605], p-valor <0,001) como en la mano débil (estimado =0,289, IC95% [0,123; 0,454], p-valor <0,001) y el IME cm2/m2. Respecto a la circunferencia muscular braquial), no alcanzamos a mostrar correlación positiva.Conclusiones: Nuestro estudio muestra que en el paciente con cáncer de cabeza y cuello la prevalencia de sarcopenia es elevada. Además, la depleción muscular evaluada mediante TC a nivel de C3 y dinamometría presenta cierta correlación, por lo que, aquellos pacientes con mayor depleción muscular a nivel de C3 presentan menor funcionalidad

Idoneidad y validez de herramientas que fomentan el aprendizaje asociativo a partir de exámenes tipo test

Depto. de Salud Pública y Materno - InfantilFac. de MedicinaFALSEsubmitte