Textural classification of land cover using support vector machines: an empirical comparison with parametric, non parametric and hybrid classifiers in the Bolivian Amazon

Land cover classification is a key research field in remote sensing and land change science as thematic maps derived from remotely sensed data have become the basis for analyzing many socio-ecological issues. However, land cover classification remains a difficult task and it is especially challenging in heterogeneous tropical landscapes where nonetheless such maps are of great importance. The present study aims to establish an efficient classification approach to accurately map all broad land cover classes in a large, heterogeneous tropical area of Bolivia, as a basis for further studies (e.g., land cover-land use change). Specifically, we compare the performance of parametric (maximum likelihood), non-parametric (k-nearest neighbour and four different support vector machines - SVM), and hybrid classifiers, using both hard and soft (fuzzy) accuracy assessments. In addition, we test whether the inclusion of a textural index (homogeneity) in the classifications improves their performance. We classified Landsat imagery for two dates corresponding to dry and wet seasons and found that non-parametric, and particularly SVM classifiers, outperformed both parametric and hybrid classifiers. We also found that the use of the homogeneity index along with reflectance bands significantly increased the overall accuracy of all the classifications, but particularly of SVM algorithms. We observed that improvements in producer’s and user’s accuracies through the inclusion of the homogeneity index were different depending on land cover classes. Earlygrowth/degraded forests, pastures, grasslands and savanna were the classes most improved, especially with the SVM radial basis function and SVM sigmoid classifiers, though with both classifiers all land cover classes were mapped with producer’s and user’s accuracies of around 90%. Our approach seems very well suited to accurately map land cover in tropical regions, thus having the potential to contribute to conservation initiatives, climate change mitigation schemes such as REDD+, and rural development policies.

The effects of sevoflurane and halothane anesthesia on cerebral blood flow velocity in children.

We compared cerebral blood flow velocity during anesthesia with sevoflurane and halothane in 23 children admitted for elective surgery (age, 0.4-9.7 yr; median age, 1.9 yr; ASA physical status I-II). Inhaled induction was performed in a randomized sequence with sevoflurane or halothane. Under steady-state conditions, cerebral blood flow velocity (systolic [V(s)], mean [V(mn)], and diastolic [VD]) were measured by a blinded investigator using transcranial pulsed Doppler ultrasonography. The anesthetic was then changed. CBFV measurements were repeated after washout of the first anesthetic and after steady-state of the second (equivalent minimal alveolar concentration to first anesthetic). The resistance index was calculated. VD and V(mn) were significantly lower during sevoflurane (V(mn) 1.35 m/s) than during halothane (V(mn) 1.50 m/s; P = 0.001), whereas V(s) was unchanged. The resistance index was lower during halothane (P < 0.001). Our results indicate lower vessel resistance and higher mean velocity during halothane than during sevoflurane. IMPLICATIONS: The mean cerebral blood flow velocity is significantly decreased in children during inhaled anesthesia with sevoflurane than during halothane. This might be relevant for the choice of anesthetic in children with risk of increased intracranial pressure, neurosurgery, or craniofacial osteotomies.

Role of Anopheles (Kerteszia) bellator as malaria vector in Southeastern Brazil (Diptera: Culicidae)

New research concerning Anopheles bellator in the southeast of the State of São Paulo, Brazil, are reported. Adult females of this mosquito showed remarkable endophily and endophagy which was even greater than An. cruzii. The epidemiological role of this anopheline as a malaria vector is discussed.

Elimination of vector-borne transmission of Chagas disease

The control of the vector-borne transmission of Chagas disease in Brazil was organized as a national program in 1975, when two large entomological and sero-epidemiological surveys were conducted in the country in order to identify areas at highest risk of transmission and to guide inerventions regarding the chemical treatment of domestic vectors of the disease. The authors present the baseline data gathered through these studies and compare them with more recent data. The evaluation performed shows that the transmission by Triatoma infestans is virtually interrupted and that the transmission by other native species of triatominae from different regions of the country is possibly very low. It is emphasized the need to maintain permanent actions of entomological surveillance in order to prevent recurrent transmission.

Differences of susceptibility of five triatomine species to pyrethroid insecticides - implications for Chagas disease vector control

As pyrethroids are presently the favored group of insecticides to control triatomines, we performed a series of bioassays to determine the intrinsic activity of some of the main compounds used in the control campaigns, against five of the main species of triatomines to be controlled. Comparing the insecticides it can be seen that lambdacyhalothrin is more effective than the other three pyrethroids, both considering the LD50 and 99 for all the three species with comparable results. On Triatoma infestans the LD50 of lambdacyhalothrin was followed by that of alfacypermethrin, cyfluthrin and deltamethrin. On Rhodnius prolixus the sequence, in decreasing order of activity, was lambdacyhalothrin, alfacypermethrin, deltamethrin and cyfluthrin. Some modifications can be seen when we compare the LD99, that has more to see to what happens in the field. T. brasiliensis showed to be as sensible to lambdacyhalothrin as T. infestans, the most susceptible for this product. By the other side T. sordida is the least susceptible considering the LD99 of this insecticide.

Oligo-Miocene extensional tectonics and fluid flow across the Northern Snake Range detachment system, Nevada

The Northern Snake Range (Nevada) represents a spectacular example of a metamorphic core complex and exposes a complete section from the mylonitic footwall into the hanging wall of a fossil detachment system. Paired geochronological and stable isotopic data of mylonitic quartzite within the detachment footwall reveal that ductile deformation and infiltration of meteoric fluids occurred between 27 and 23 Ma. Ar-40/Ar-39 ages display complex recrystallization-cooling relationships but decrease systematically from 26.9 +/- 0.2 Ma at the top to 21.3 +/- 0.2 Ma at the bottom of footwall mylonite. Hydrogen isotope (delta D) values in white mica are very low (-150 to -145 %) within the top 80-90 m of detachment footwall, in contrast to values obtained from the deeper part of the section where values range from -77 to -64 %, suggesting that time-integrated interaction between rock and meteoric fluid was restricted to the uppermost part of the mylonitic footwall. Pervasive mica-water hydrogen isotope exchange is difficult to reconcile with models of Ar-40 loss during mylonitization solely by volume diffusion. Rather, we interpret the Ar-40/Ar-39 ages of white mica with low-delta D values to date syn-mylonitic hydrogen and argon isotope exchange, and we conclude that the hydrothermal system of the Northern Snake Range was active during late Oligocene (27-23 Ma) and has been exhumed by the combined effects of ductile strain, extensional detachment faulting, and erosion.

Immunological evaluation of human immunedeficiency virus infected individuals by flow cytometry

Human immunodeficiency virus (HIV) infection heavily compromises the immune system. The decrease of the T cell CD4+ subset along the evolution to acquired immunodeficiency syndrome has been considered as a hallmark of HIV infection. In this paper we review some aspects of the immunopathology of HIV infection and discuss the importance of the flow cytometry for the evaluation of the T lymphocyte subsets in the follow-up of HIV infected children and adults, and for the monitoring of the immune reconstitution upon antiretroviral therapy.

Detection of intracytoplasmic cytokines by flow cytometry

Flow cytometry has been used as a powerful technique for studying cell surface antigen expression as well as intracellular molecules. Its capability of analyzing multiple parameters simultaneously on a single cell has allowed identification and studies of functional cell subsets within heterogeneous populations. In this respect, several techniques have been developed during the past few years to study cytokine-producing cells by flow cytometry in humans and several animal models.

Applications of flow cytometry to hematopoietic stem cell transplantation

Applications of flow cytometry to clinical and experimental hematopoietic stem cell transplantation (HSCT) are discussed in this review covering the following topics: diagnosis and classification of lymphohematologic disorders, quantitation of hematopoietic progenitors in the graft, lymphohematopoietic reconstitution following HSCT and animal models of human HSCT. At the end, the utilization of flow cytometry in clinical HSCT by Brazilian transplant centers is briefly reviewed.

Procedures to characterize and study P2Z/P2X7 purinoceptor: flow cytometry as a promising practical, reliable tool

The expression of P2Z/P2X7 purinoceptor in different cell types is well established. This receptor is a member of the ionotropic P2X receptor family, which is composed by seven cloned receptor subtypes (P2X1 - P2X7). Interestingly, the P2Z/P2X7 has a unique feature of being linked to a non-selective pore which allows the passage of molecules up to 900 Da depending on the cell type. Early studies of P2Z/P2X7 purinoceptor were exclusively based on classical pharmacological studies but the recent tools of molecular biology have enriched the analysis of the receptor expression. The majority of assays and techniques chosen so far to study the expression of P2Z/P2X7 receptor explore directly or indirectly the effects of the opening of P2Z/P2X7 linked pore. In this review we describe the main techniques used to study the expression and functionality of P2Z/P2X7 receptor. Additionally, the increasing need and importance of a multifunctional analysis of P2Z/P2X7 expression based on flow cytometry technology is discussed, as well as the adoption of a more complete analysis of P2Z/P2X7 expression involving different techniques.

Flow cytometry in the study of cell death

In this report we present a concise review concerning the use of flow cytometric methods to characterize and differentiate between two different mechanisms of cell death, apoptosis and necrosis. The applications of these techniques to clinical and basic research are also considered. The following cell features are useful to characterize the mode of cell death: (1) activation of an endonuclease in apoptotic cells results in extraction of the low molecular weight DNA following cell permeabilization, which, in turn, leads to their decreased stainability with DNA-specific fluorochromes. Measurements of DNA content make it possible to identify apoptotic cells and to recognize the cell cycle phase specificity of apoptotic process; (2) plasma membrane integrity, which is lost in necrotic but not in apoptotic cells; (3) the decrease in forward light scatter, paralleled either by no change or an increase in side scatter, represent early changes during apoptosis. The data presented indicate that flow cytometry can be applied to basic research of the molecular and biochemical mechanisms of apoptosis, as well as in the clinical situations, where the ability to monitor early signs of apoptosis in some systems may be predictive for the outcome of some treatment protocols.