Detection of phospholipid oxidation in oxidatively stressed cells by reversed-phase HPLC coupled with positive-ionization electrospray MS

Measurement of lipid peroxidation is a commonly used method of detecting oxidative damage to biological tissues, but the most frequently used methods, including MS, measure breakdown products and are therefore indirect. We have coupled reversed-phase HPLC with positive-ionization electrospray MS (LC-MS) to provide a method for separating and detecting intact oxidized phospholipids in oxidatively stressed mammalian cells without extensive sample preparation. The elution profile of phospholipid hydroperoxides and chlorohydrins was first characterized using individual phospholipids or a defined phospholipid mixture as a model system. The facility of detection of the oxidized species in complex mixtures was greatly improved compared with direct-injection MS analysis, as they eluted earlier than the native lipids, owing to the decrease in hydrophobicity. In U937 and HL60 cells treated in vitro with t-butylhydroperoxide plus Fe2+, lipid oxidation could not be observed by direct injection, but LC-MS allowed the detection of monohydroperoxides of palmitoyl-linoleoyl and stearoyl-linoleoyl phosphatidylcholines. The levels of hydroperoxides observed in U937 cells were found to depend on the duration and severity of the oxidative stress. In cells treated with HOCl, chlorohydrins of palmitoyloleoyl phosphatidylcholine were observed by LC-MS. The method was able to detect very small amounts of oxidized lipids compared with the levels of native lipids present. The membrane-lipid profiles of these cells were found to be quite resistant to damage until high concentrations of oxidants were used. This is the first report of direct detection by LC-MS of intact oxidized phospholipids induced in cultured cells subjected to oxidative stress.

Cost-effective node monitoring for online hot event detection in sina weibo microblogging

We propose a cost-effective hot event detection system over Sina Weibo platform, currently the dominant microblogging service provider in China. The problem of finding a proper subset of microbloggers under resource constraints is formulated as a mixed-integer problem for which heuristic algorithms are developed to compute approximate solution. Preliminary results show that by tracking about 500 out of 1.6 million candidate microbloggers and processing 15,000 microposts daily, 62% of the hot events can be detected five hours on average earlier than they are published by Weibo.

Semantic feature-based visual attention model for pedestrian detection

Objective
Pedestrian detection under video surveillance systems has always been a hot topic in computer vision research. These systems are widely used in train stations, airports, large commercial plazas, and other public places. However, pedestrian detection remains difficult because of complex backgrounds. Given its development in recent years, the visual attention mechanism has attracted increasing attention in object detection and tracking research, and previous studies have achieved substantial progress and breakthroughs. We propose a novel pedestrian detection method based on the semantic features under the visual attention mechanism.
Method
The proposed semantic feature-based visual attention model is a spatial-temporal model that consists of two parts: the static visual attention model and the motion visual attention model. The static visual attention model in the spatial domain is constructed by combining bottom-up with top-down attention guidance. Based on the characteristics of pedestrians, the bottom-up visual attention model of Itti is improved by intensifying the orientation vectors of elementary visual features to make the visual saliency map suitable for pedestrian detection. In terms of pedestrian attributes, skin color is selected as a semantic feature for pedestrian detection. The regional and Gaussian models are adopted to construct the skin color model. Skin feature-based visual attention guidance is then proposed to complete the top-down process. The bottom-up and top-down visual attentions are linearly combined using the proper weights obtained from experiments to construct the static visual attention model in the spatial domain. The spatial-temporal visual attention model is then constructed via the motion features in the temporal domain. Based on the static visual attention model in the spatial domain, the frame difference method is combined with optical flowing to detect motion vectors. Filtering is applied to process the field of motion vectors. The saliency of motion vectors can be evaluated via motion entropy to make the selected motion feature more suitable for the spatial-temporal visual attention model.
Result
Standard datasets and practical videos are selected for the experiments. The experiments are performed on a MATLAB R2012a platform. The experimental results show that our spatial-temporal visual attention model demonstrates favorable robustness under various scenes, including indoor train station surveillance videos and outdoor scenes with swaying leaves. Our proposed model outperforms the visual attention model of Itti, the graph-based visual saliency model, the phase spectrum of quaternion Fourier transform model, and the motion channel model of Liu in terms of pedestrian detection. The proposed model achieves a 93% accuracy rate on the test video.
Conclusion
This paper proposes a novel pedestrian method based on the visual attention mechanism. A spatial-temporal visual attention model that uses low-level and semantic features is proposed to calculate the saliency map. Based on this model, the pedestrian targets can be detected through focus of attention shifts. The experimental results verify the effectiveness of the proposed attention model for detecting pedestrians.

The queen is dead-long live the workers: intraspecific parasitism by workers in the stingless bee Melipona scutellaris

Insect societies are well known for their high degree of cooperation, but their colonies can potentially be exploited by reproductive workers who lay unfertilized, male eggs, rather than work for the good of the colony. Recently, it has also been discovered that workers in bumblebees and Asian honeybees can succeed in entering and parasitizing unrelated colonies to produce their own male offspring. The aim of this study was to investigate whether such intraspecific worker parasitism might also occur in stingless bees, another group of highly social bees. Based on a large-scale genetic study of the species Melipona scutellaris, and the genotyping of nearly 600 males from 45 colonies, we show that similar to 20% of all males are workers` sons, but that around 80% of these had genotypes that were incompatible with them being the sons of workers of the resident queen. By tracking colonies over multiple generations, we show that these males were not produced by drifted workers, but rather by workers that were the offspring of a previous, superseded queen. This means that uniquely, workers reproductively parasitize the next-generation workforce. Our results are surprising given that most colonies were sampled many months after the previous queen had died and that workers normally only have a life expectancy of similar to 30 days. It also implies that reproductive workers greatly outlive all other workers. We explain our results in the context of kin selection theory, and the fact that it pays workers more from exploiting the colony if costs are carried by less related individuals.

Mimicry of host cuticular hydrocarbons by salticid spider Cosmophasis bitaeniata that preys on larvae of tree ants Oecophylla smaragdina

The salticid spider Cosmophasis bitaeniata preys on the larvae of the green tree ant Oecophylla smaragdina. Gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS) reveal that the cuticle of C. bitaeniata mimics the mono- and dimethylalkanes of the cuticle of its prey. Recognition bioassays with extracts of the cuticular hydrocarbons of ants and spiders revealed that foraging major workers did not respond aggressively to the extracts of the spiders or conspecific nestmates, but reacted aggressively to conspecific nonnestmates. Typically, the ants either failed to react (as with control treatments with no extracts) or they reacted nonaggressively as with conspecific nestmates. These data indicate that the qualitative chemical mimicry of ants by C. bitaeniata allows the spiders to avoid detection by major workers of O. smaragdina.

Tactile threshold detection in leprosy patients with an electronic algometer

Objective: To propose an electronic method for sensitivity evaluation in leprosy and to compare it to the Semmes-Weinstein monofilaments. Methods:Thirty patients attending the Dermatology outpatient clinic of HCFMRP-USP were consecutively evaluated by both the electronic aesthesiometer and Semmes-Weinstein monofilaments on hand and foot test points. The intraclass correlation coefficient (ICC) was calculated to determine the variability of the electronic measures and the Kappa coefficient was calculated to determine the agreement between methods according to their categories (altered and non-altered tactile sensitivity). Results: The ICC was approximately 1, demonstrating repeatability. The Kappa coefficient showed more than 75 and 63% agreement on the hand and foot points, respectively. The mean agreement between the 2 methods for the 7 points of the right and left hand was 77.14 and 75.71%, respectively. The mean agreement for all 10 points was 74.33 and 63.66% on the right and left foot, respectively. In cases of disagreement the detection of altered tactile sensitivity by the electronic esthesiometer on the right and left foot was 90.91 and 84.25%, respectively, with no detection by the monofilaments. Conclusion: The results suggest that the electronic esthesiometer is a reliable and easy application, capable of evaluating alterations of tactile sensitivity in leprosy patients. (C) 2009 Elsevier B.V. All rights reserved.

Detection of Bartonella spp. in neotropical felids and evaluation of risk factors and hematological abnormalities associated with infection

Although antibodies to Bartonella henselae have been described in all neotropical felid species, DNA has been detected in only one species, Leopard us wiedii. The aim of this study was to determine whether DNA of Bartonella spp. could be detected in blood of other captive neotropical felids and evaluate risk factors and hematological findings associated with infection. Blood samples were collected from 57 small felids, including 1 Leopard us geoffroyi, 17 L wiedii, 22 Leopardus tigrinus, 14 Leopardus pardalis, and 3 Puma yagouaroundi; 10 blood samples from Panthera onca were retrieved from blood banks. Complete blood counts were performed on blood samples from small felids, while all samples were evaluated by PCR. DNA extraction was confirmed by amplification of the cat GAPDH gene. Bartonella spp. were assessed by amplifying a fragment of their 16S-23S rRNA intergenic spacer region; PCR products were purified and sequenced. For the small neotropical felids, risk factors [origin (wild-caught or zoo-born), gender, felid species, and flea exposure) were evaluated using exact multiple logistic regression. Hematological findings (anemia, polycythemia/hyperproteinemia, leukocytosis and leukopenia) were tested for association with infection using Fisher`s exact test. The 635 bp product amplified from 10 samples (10/67 = 14.92%) was identified as B. henselae by sequencing. Small neotropical felid males were more likely to be positive than females (95% CI = 0.00-0.451, p = 0.0028), however other analyzed variables were not considered risk factors (p > 0.05). Hematological abnormalities were not associated with infection (p > 0.05). This is the first report documenting B. henselae detection by PCR in several species of neotropical felids. (C) 2009 Elsevier B.V. All rights reserved.

Deteção e acompanhamento de movimento através de uma câmara de vídeo

A deteção e seguimento de pessoas tem uma grande variedade de aplicações em visão computacional. Embora tenha sido alvo de anos de investigação, continua a ser um tópico em aberto, e ainda hoje, um grande desafio a obtenção de uma abordagem que inclua simultaneamente exibilidade e precisão. O trabalho apresentado nesta dissertação desenvolve um caso de estudo sobre deteção e seguimento automático de faces humanas, em ambiente de sala de reuniões, concretizado num sistema flexível de baixo custo. O sistema proposto é baseado no sistema operativo GNU's Not Unix (GNU) linux, e é dividido em quatro etapas, a aquisição de vídeo, a deteção da face, o tracking e reorientação da posição da câmara. A aquisição consiste na captura de frames de vídeo das três câmaras Internet Protocol (IP) Sony SNC-RZ25P, instaladas na sala, através de uma rede Local Area Network (LAN) também ele já existente. Esta etapa fornece os frames de vídeo para processamento à detecção e tracking. A deteção usa o algoritmo proposto por Viola e Jones, para a identificação de objetos, baseando-se nas suas principais características, que permite efetuar a deteção de qualquer tipo de objeto (neste caso faces humanas) de uma forma genérica e em tempo real. As saídas da deteção, quando é identificado com sucesso uma face, são as coordenadas do posicionamento da face, no frame de vídeo. As coordenadas da face detetada são usadas pelo algoritmo de tracking, para a partir desse ponto seguir a face pelos frames de vídeo subsequentes. A etapa de tracking implementa o algoritmo Continuously Adaptive Mean-SHIFT (Camshift) que baseia o seu funcionamento na pesquisa num mapa de densidade de probabilidade, do seu valor máximo, através de iterações sucessivas. O retorno do algoritmo são as coordenadas da posição e orientação da face. Estas coordenadas permitem orientar o posicionamento da câmara de forma que a face esteja sempre o mais próximo possível do centro do campo de visão da câmara. Os resultados obtidos mostraram que o sistema de tracking proposto é capaz de reconhecer e seguir faces em movimento em sequências de frames de vídeo, mostrando adequabilidade para aplicação de monotorização em tempo real.

Seguimento de pessoas em sistemas multi-câmara

Trabalho Final de Mestrado para obtenção do grau de Mestre em Engenharia de Redes de Comunicação e Multimédia

People counting system using existing surveillance video camera

The Casa da Música Foundation, responsible for the management of Casa da Música do Porto building, has the need to obtain statistical data related to the number of building’s visitors. This information is a valuable tool for the elaboration of periodical reports concerning the success of this cultural institution. For this reason it was necessary to develop a system capable of returning the number of visitors for a requested period of time. This represents a complex task due to the building’s unique architectural design, characterized by very large doors and halls, and the sudden large number of people that pass through them in moments preceding and proceeding the different activities occurring in the building. To achieve the technical solution for this challenge, several image processing methods, for people detection with still cameras, were first studied. The next step was the development of a real time algorithm, using OpenCV libraries and computer vision concepts,to count individuals with the desired accuracy. This algorithm includes the scientific and technical knowledge acquired in the study of the previous methods. The themes developed in this thesis comprise the fields of background maintenance, shadow and highlight detection, and blob detection and tracking. A graphical interface was also built, to help on the development, test and tunning of the proposed system, as a complement to the work. Furthermore, tests to the system were also performed, to certify the proposed techniques against a set of limited circumstances. The results obtained revealed that the algorithm was successfully applied to count the number of people in complex environments with reliable accuracy.

Adenovirus respiratory infection: significant increase in diagnosis using PCR comparing with antigen detection and culture methods

Adenovirus (AdV) respiratory infections are usually described as being associated with high mortality rates. Laboratory diagnosis is essential for the establishment of the appropriate therapy, and for guiding the implementation of preventive measures in order to prevent the spread of the infection. Aiming to analyze the sensitivity and specificity of the laboratorial diagnosis methods available, we compared antigen detection by indirect immunofluorescence assay (IF), and a specific nested polymerase chain reaction (PCR), to detect AdV in respiratory samples collected from patients admitted to hospital with acute respiratory disease. Positive samples were inoculated into a cell culture to confirm the results. We analyzed 381 samples from the nasopharyngeal aspirates collected during the year 2008; of these, 2.6% tested were positive for adenovirus through IF and 10% through PCR; positive isolation was obtained in 40% and 26% of these cases, respectively. Most infected patients were children under six months of age, and despite of the fact that a significant number of patients required intensive care, the mortality rate was low (5%). In conclusion, molecular methods were found to be useful for rapid diagnosis of adenovirus infections with higher sensitivity than antigen detection; their introduction permitted a significant increase in diagnoses of adenovirus infections.

Bacterial peptidoglycan biosynthesis and recognition by the innate immune system

Dissertation presented to obtain the Ph.D degree in Biology

Indirect hydrogen analysis by gas chromatography coupled to mass spectrometry (GC-MS).

Gas chromatography (GC) is an analytical tool very useful to investigate the composition of gaseous mixtures. The different gases are separated by specific columns but, if hydrogen (H2 ) is present in the sample, its detection can be performed by a thermal conductivity detector or a helium ionization detector. Indeed, coupled to GC, no other detector can perform this detection except the expensive atomic emission detector. Based on the detection and analysis of H2 isotopes by low-pressure chemical ionization mass spectrometry (MS), a new method for H2 detection by GC coupled to MS with an electron ionization ion source and a quadrupole analyser is presented. The presence of H2 in a gaseous mixture could easily be put in evidence by the monitoring of the molecular ion of the protonated carrier gas. Copyright © 2013 John Wiley & Sons, Ltd.

Study of two different enzyme immunoassays for the detection of Mayaro virus antibodies

This paper presents the evaluation of an enzyme immunoassay in which Mayaro virus-infected cultured cells ara used as antigen (EIA-ICC) and an IgM antibody capture ELISA (MAC-ELISA) for Mayaro serologic diagnosis using 114 human sera obtained during a Mayaro outbreak occurred in Bolivia, in 1987. Results were compared with those obtained by haemagglutination-inhibition test (HAI). MAC-ELISA was the most sensitive technique for anti-Mayaro IgM detection. MAC-ELISA was twice sensitive as IgM EIA-ICC. The data shows that MAC-ELISA is a practical and valid technique for diagnosis of recent mayaro infection. IgG-ICC showed hight sensitivity and high specificity compared to HAI. The combination of anti-Mayaro IgG and IgM EIA-ICC results presented the highest sensitivity of the study. Anti-Mayaro IgG and IgM simultaneous detection by ELISA-ICC can be used for recent infection diagnosis (in spite of a less sensitive IgM detection than by MAC-ELISA), for surveillance and sero-epidemiologic studies, and for studies of IgG and IgM responses to Mayaro infection.

Quantifying rates of landscape evolution and tectonic processes by thermochronology and numerical modeling of crustal heat transport using PECUBE

PECUBE is a three-dimensional thermal-kinematic code capable of solving the heat production-diffusion-advection equation under a temporally varying surface boundary condition. It was initially developed to assess the effects of time-varying surface topography (relief) on low-temperature thermochronological datasets. Thermochronometric ages are predicted by tracking the time-temperature histories of rock-particles ending up at the surface and by combining these with various age-prediction models. In the decade since its inception, the PECUBE code has been under continuous development as its use became wider and addressed different tectonic-geomorphic problems. This paper describes several major recent improvements in the code, including its integration with an inverse-modeling package based on the Neighborhood Algorithm, the incorporation of fault-controlled kinematics, several different ways to address topographic and drainage change through time, the ability to predict subsurface (tunnel or borehole) data, prediction of detrital thermochronology data and a method to compare these with observations, and the coupling with landscape-evolution (or surface-process) models. Each new development is described together with one or several applications, so that the reader and potential user can clearly assess and make use of the capabilities of PECUBE. We end with describing some developments that are currently underway or should take place in the foreseeable future. (C) 2012 Elsevier B.V. All rights reserved.