Adaptive spatio-temporal filter for low-cost camera depth maps

In this paper we present an adaptive spatio-temporal filter that aims to improve low-cost depth camera accuracy and stability over time. The proposed system is composed by three blocks that are used to build a reliable depth map of static scenes. An adaptive joint-bilateral filter is used to obtain consistent depth maps by jointly considering depth and video information and by adapting its parameters to different levels of estimated noise. Kalman filters are used to reduce the temporal random fluctuations of the measurements. Finally an interpolation algorithm is used to obtain consistent depth maps in the regions where the depth information is not available. Results show that this approach allows to considerably improve the depth maps quality by considering spatio-temporal information and by adapting its parameters to different levels of noise.

Evaluación para el aprendizaje en la asignatura sistemas operativos en modalidad online: un estudio cualitativo basado en la taxonomía de Bloom

La asignatura Sistemas Operativos presenta dificultades para su aprendizaje, pero poco se conoce acerca de las mismas, ya que no han sido determinadas ni estudiadas por la literatura. Asimismo, los trabajos existentes sobre la enseñanza y aprendizaje de Sistemas Operativos se limitan a proponer distintos enfoques para impartir la asignatura y en general no evalúan el aprendizaje de los estudiantes para comprobar la eficacia del método propuesto ni usan metodologías de investigación rigurosas. Por otra parte, la impartición de la asignatura Sistemas Operativos en modalidad online ha sido escasamente estudiada y podría tener dificultades adicionales a las de la modalidad presencial, ya que el contexto online impone una serie de restricciones tanto para el profesor como para el estudiante. En la presente tesis se ha llevado a cabo una evaluación formativa en la asignatura Sistemas Operativos, perteneciente al Grado de Ingeniería Informática de una universidad online. El objetivo inicial de la evaluación era descubrir las dificultades de los estudiantes para la comprensión de los conceptos de la asignatura. Posteriormente y, dada la buena aceptación de la evaluación por parte de los estudiantes, se ampliaron los objetivos del trabajo para explorar los efectos de la evaluación realizada sobre el aprendizaje. La evaluación formativa diseñada está basada en la taxonomía revisada de Bloom y sus principales objetivos son: (a) promover el aprendizaje significativo y (b) hacer a los estudiantes conscientes de su proceso de aprendizaje. La metodología de investigación utilizada es el estudio de caso cualitativo y la muestra está constituida por 9 estudiantes del total de 13 matriculados en la asignatura. Los datos cualitativos analizados proceden de las pruebas de evaluación formativa llevadas a cabo por los estudiantes durante la impartición de la asignatura. Los conceptos de sistemas operativos que han resultado más difíciles de comprender en el curso online estudiado han sido las interrupciones y los semáforos. Además, alrededor de estos conceptos se han identificado las dificultades específicas y sus posibles causas. Las dificultades descubiertas acerca de los semáforos corroboran las investigaciones existentes en el área de programación concurrente. El resto de las dificultades identificadas no habían sido determinadas por la literatura existente. En cuanto a los efectos de la evaluación formativa sobre el aprendizaje, la evidencia empírica muestra que ésta ha provocado en los estudiantes una reflexión profunda sobre los conceptos de la asignatura y sobre su propio proceso de aprendizaje. El estudio de caso presentado puede ayudar a los profesores del área de ingeniería a crear evaluaciones formativas en cursos online. La tesis, por tanto, realiza aportaciones relevantes en las áreas de enseñanza y aprendizaje de sistemas operativos, evaluación formativa, metodologías cualitativas y educación online. ABSTRACT Operating Systems is a difficult subject to learn; however little is known about said difficulties, as they have not been studied nor determined by the relevant literature. Existing studies on teaching and learning the subject of operating systems are limited to presenting different approaches for teaching the subject and generally do not evaluate students’ learning to verify the effectiveness of the proposed methods, nor do they use rigorous research methodologies. On the other hand, there are very few studies on teaching operating systems online, which may inherently present more difficulties than the in-person format, since an online context imposes a series of restrictions on both professors and students, such as not having face-to-face interaction for communications. This thesis studies a formative assessment of the subject of operating systems, as part of the Degree in Information Technology Engineering for an online university. The initial objective of this assessment was to determine the students’ difficulties in conceptual comprehension for this subject. Once students had accepted the assessment, the study’s objectives were expanded to include an investigation of the effects of the assessment on learning. The designed formative assessment was based on Revised Bloom’s Taxonomy with the following main objectives: (a) to promote meaningful learning and (b) (b) to make students aware of their learning process. The research methodology involves a qualitative case study with a sample consisting of 9 of the total 13 students registered for this course. The qualitative data analyzed comes from the formative assessment tests taken by these students during the course. The most difficult operating systems concepts for students in the online course were interrupts and semaphores. Additionally, the specific difficulties and their possible causes have been identified. The students’ comprehension difficulties with semaphores corroborate the existing research in the area of concurrent programming. The other identified difficulties were not discussed in the existing literature. Regarding the effects of the formative assessment on learning, the empirical evidence shows that it causes students to reflect carefully on the subject’s concepts as well as their own learning process. The presented case study can help professors in the area of engineering to create formative assessments for online courses. This thesis, therefore, makes relevant contributions to the areas of teaching and learning operating systems, formative assessment, qualitative methodologies, and online education.

Design of a Two-Phase buck converter with fourth-order output filter for envelope amplifiers of limited bandwidth

The use of techniques such as envelope tracking (ET) and envelope elimination and restoration (EER) can improve the efficiency of radio frequency power amplifiers (RFPA). In both cases, high-bandwidth DC/DC converters called envelope amplifiers (EA) are used to modulate the supply voltage of the RFPA. This paper addresses the analysis and design of a modified two-phase Buck converter optimized to operate as EA. The effects of multiphase operation on the tracking capabilities are analyzed. The use of a fourth-order output filter is proposed to increase the attenuation of the harmonics generated by the PWM operation, thus allowing a reduction of the ratio between the switching frequency and the converter bandwidth. The design of the output filter is addressed considering envelope tracking accuracy and distortion caused by the side bands arising from the nonlinear modulation process. Finally, the proposed analysis and design methods are supported by simulation results, as well as demonstrated by experiments obtained using two 100-W, 10-MHz, two-phase Buck EAs capable of accurately tracking a 1.5-MHz bandwidth OFDM signal.

The DNA Helicase Activity of BLM Is Necessary for the Correction of the Genomic Instability of Bloom Syndrome Cells

Bloom syndrome (BS) is a rare autosomal recessive disorder characterized by growth deficiency, immunodeficiency, genomic instability, and the early development of cancers of many types. BLM, the protein encoded by BLM, the gene mutated in BS, is localized in nuclear foci and absent from BS cells. BLM encodes a DNA helicase, and proteins from three missense alleles lack displacement activity. BLM transfected into BS cells reduces the frequency of sister chromatid exchanges and restores BLM in the nucleus. Missense alleles fail to reduce the sister chromatid exchanges in transfected BS cells or restore the normal nuclear pattern. BLM complements a phenotype of a Saccharomyces cerevisiae sgs1 top3 strain, and the missense alleles do not. This work demonstrates the importance of the enzymatic activity of BLM for its function and nuclear localization pattern.

Nuclear structure in normal and Bloom syndrome cells

Bloom syndrome (BS) is a rare cancer-predisposing disorder in which the cells of affected persons have a high frequency of somatic mutation and genomic instability. BLM, the protein altered in BS, is a RecQ DNA helicase. This report shows that BLM is found in the nucleus of normal human cells in the nuclear domain 10 or promyelocytic leukemia nuclear bodies. These structures are punctate depots of proteins disrupted upon viral infection and in certain human malignancies. BLM is found primarily in nuclear domain 10 except during S phase when it colocalizes with the Werner syndrome gene product, WRN, in the nucleolus. BLM colocalizes with a select subset of telomeres in normal cells and with large telomeric clusters seen in simian virus 40-transformed normal fibroblasts. During S phase, BS cells expel micronuclei containing sites of DNA synthesis. BLM is likely to be part of a DNA surveillance mechanism operating during S phase.

Sodium channel selectivity filter regulates antiarrhythmic drug binding

Local anesthetic antiarrhythmic drugs block Na+ channels and have important clinical uses. However, the molecular mechanism by which these drugs block the channel has not been established. The family of drugs is characterized by having an ionizable amino group and a hydrophobic tail. We hypothesized that the charged amino group of the drug may interact with charged residues in the channel’s selectivity filter. Mutation of the putative domain III selectivity filter residue of the adult rat skeletal muscle Na+ channel (μ1) K1237E increased resting lidocaine block, but no change was observed in block by neutral analogs of lidocaine. An intermediate effect on the lidocaine block resulted from K1237S and there was no effect from K1237R, implying an electrostatic effect of Lys. Mutation of the other selectivity residues, D400A (domain I), E755A (domain II), and A1529D (domain IV) allowed block by externally applied quaternary membrane-impermeant derivatives of lidocaine (QX314 and QX222) and accelerated recovery from block by internal QX314. Neo-saxitoxin and tetrodotoxin, which occlude the channel pore, reduced the amount of QX314 bound in D400A and A1529D, respectively. Block by outside QX314 in E755A was inhibited by mutation of residues in transmembrane segment S6 of domain IV that are thought to be part of an internal binding site. The results demonstrate that the Na+ channel selectivity filter is involved in interactions with the hydrophilic part of the drugs, and it normally limits extracellular access to and escape from their binding site just within the selectivity filter. Participation of the selectivity ring in antiarrhythmic drug binding and access locates this structure adjacent to the S6 segment.

Isolation of anti-angiogenesis antibodies from a large combinatorial repertoire by colony filter screening

We describe here a method, based on iterative colony filter screening, for the rapid isolation of binding specificities from a large synthetic repertoire of human antibody fragments in single-chain Fv configuration. Escherichia coli cells, expressing the library of antibody fragments, are grown on a porous master filter, in contact with a second filter coated with the antigen, onto which antibodies secreted by the bacteria are able to diffuse. Detection of antigen binding on the second filter allows the recovery of a number of E.coli cells, including those expressing the binding specificity of interest, which can be submitted to a second round of screening for the isolation of specific monoclonal antibodies. We tested the methodology using as antigen the ED-B domain of fibronectin, a marker of angiogenesis. From an antibody library of 7 × 108 clones, we recovered a number of specifically-binding antibodies of different aminoacid sequence. The antibody clone showing the strongest enzyme-linked immunosorbent assay signal (ME4C) was further characterised. Its epitope on the ED-B domain was mapped using the SPOT synthesis method, which uses a set of decapeptides spanning the antigen sequence synthesised and anchored on cellulose. ME4C binds to the ED-B domain with a dissociation constant Kd = 1 × 10–7 M and specifically stains tumour blood vessels, as shown by immunohistochemical analysis on tumour sections of human and murine origin.

Filtro respiratório reduz efeitos cardiovasculares associados à poluição: estudo randomizado, duplo-cego, controlado e cruzado em pacientes com insuficiência cardíaca (FILTER-HF trial)

Introdução A poluição do ar é um fator de risco associado com descompensação e mortalidade em pacientes com insuficiência cardíaca (IC). Objetivo Avaliar o impacto de um filtro de polipropileno sobre desfechos cardiovasculares em pacientes com IC e voluntários saudáveis durante exposição controlada à poluição. Métodos Ensaio clínico duplocego, controlado e cruzado, incluindo 26 pacientes com IC e 15 voluntários saudáveis, expostos a três protocolos diferentes de inalação randomizados por ordem: Ar Limpo; Exposição à Partículas de Exaustão do Diesel (ED); e ED filtrada. Os desfechos estudados foram função endotelial por índice de hiperemia reativa (RHi) e índice de aumento (Aix), biomarcadores séricos, variáveis de teste cardiopulmonar submáximo (caminhada de seis-minutos [tc6m]; consumo de oxigênio [VO2]; equivalente ventilatório de gás carbônico [VE/VCO2 slope]; consumo de O2 por batida [PulsoO2]) e variabilidade da frequência cardíaca (VFC). Resultados No grupo IC, a ED piorou o RHi [de 2,17 (IQR: 1,8-2,5) para 1,72 (IQR: 1,5-2,2); p=0,002], reduziu o VO2 [de 11.0 ± 3.9 para 8.4±2.8ml/Kg/min; p < 0.001], o tc6m [de 243,3±13 para 220,8 ± 14m; p=0,030] e o PulsoO2 [de 8.9 ± 1.0 para 7.8±0.7ml/bpm; p < 0.001]; e aumentou o BNP [de 47,0pg/ml (IQR: 17,3-118,0) para 66,5pg/ml (IQR: 26,5-155,5); p=0,004]. O filtro foi capaz de reduzir a concentração de poluição de 325±31 para 25±6?g/m3 (p < 0,001 vs. ED). No grupo IC, o filtro foi associado com melhora no RHi [2,06 (IQR: 1,5-2,6); p=0,019 vs. ED); aumento no VO2 (10.4 ± 3.8ml/Kg/min; p < 0.001 vs. ED) e PulsoO2 (9.7±1.1ml/bpm; p < 0.001 vs. ED); e redução no BNP [44,0pg/ml (IQR: 20,0-110,0); p=0,015 vs. ED]. Em ambos os grupos, a ED reduziu o Aix, sem efeito do filtro. O uso do filtro foi associado com maior ventilação e reinalação de CO2. Outras variáveis pesquisadas como VE/VCO2 slope e VFC não sofreram influências entre os protocolos. Conclusão A poluição do ar afetou adversamente o desempenho cardiovascular de pacientes com IC. Este é o primeiro ensaio clínico demonstrando que um simples filtrorespiratório pode prevenir a disfunção endotelial, a intolerância ao exercício e o aumento do BNP associados à poluição em pacientes com IC. O uso de máscaras com filtro tem o potencial de reduzir a morbidade associada à IC. Identificador ClinicalTrials.gov: NCT01960920

Land use practices near tributary rivers and their influence on duckweed (Lemna obscura) bloom in the southern part of Lake Maracaibo, Venezuela: Sustainable solutions to address the issue

This study examined the relationship between land-use practices near tributary rivers in South Lake Maracaibo and the appearance of duckweed (Lemna obscura) in the lake. Four rivers were studied: The Mucujepe, Capaz, Guamo and Frio. Eight factors were assessed: rivers, sediments, erosion, soils, fertilizers, water quality, land use activities and vegetation corridors. Satellite images, official cartography, field visits and observations, water samples and personal communication with organizations involved were held to get an accurate and current assessment of the conditions. The study revealed the land-use practices surrounding the Pan-American Zone Rivers contribute to the duckweed blooming in Lake Maracaibo.

A novel information theory method for filter feature selection

In this paper, we propose a novel filter for feature selection. Such filter relies on the estimation of the mutual information between features and classes. We bypass the estimation of the probability density function with the aid of the entropic-graphs approximation of Rényi entropy, and the subsequent approximation of the Shannon one. The complexity of such bypassing process does not depend on the number of dimensions but on the number of patterns/samples, and thus the curse of dimensionality is circumvented. We show that it is then possible to outperform a greedy algorithm based on the maximal relevance and minimal redundancy criterion. We successfully test our method both in the contexts of image classification and microarray data classification.

Abundance and biomass of protozooplankton from the iron-induced phytoplankton bloom during the EisenEx experiment in 2000 in the Southern Ocean

The responses of larger (>50 µm in diameter) protozooplankton groups to a phytoplankton bloom induced by in situ iron fertilization (EisenEx) in the Polar Frontal Zone (PFZ) of the Southern Ocean in austral spring are presented. During the 21 days of the experiment, samples were collected from seven discrete depths in the upper 150 m inside and outside the fertilized patch for the enumeration of acantharia, foraminifera, radiolaria, heliozoa, tintinnid ciliates and aplastidic thecate dinoflagellates. Inside the patch, acantharian numbers increased twofold, but only negligibly in surrounding waters. This finding is of major interest, since acantharia are suggested to be involved in the formation of barite (BaSO_4 ) found in sediments and which is a palaeoindicator of both ancient and modern high productivity regimes. Foraminifera increased significantly in abundance inside and outside the fertilized patch. However the marked increase of juveniles after a full moon event suggests a lunar periodicity in the reproduction cycle of some foraminiferan species rather than a reproductive response to enhanced food availability. In contrast, adult radiolaria showed no clear trend during the experiment, but juveniles increased threefold indicating elevated reproduction. Aplastidic thecate dinoflagellates almost doubled in numbers and biomass, but also increased outside the patch. Tintinnid numbers decreased twofold, although biomass remained constant due to a shift in the size spectrum. Empty tintinnid loricae, however, increased by a factor of two indicating that grazing pressure on this group mainly by copepods intensified during EisenEx. The results show that iron-fertilization experiments can shed light on the biology and the role of these larger protists in pelagic ecosystem which will improve their use as proxies in palaeoceanography.