José Aparecido da Silva

Contactless conductivity detection for capillary electrophoresis: Hardware improvements and optimization of the input-signal amplitude and frequency

A new prototype of contactless conductivity detector, smaller and easier to operate than the former version, is described. For a fused-silica capillary with 142-microm wall thickness and voltages up to 25 kV, it can be placed at the low- or high-voltage end of the column. This feature allowed implementation of an apparatus with sample introduction at the grounded end of the column. The input signal is an important parameter for determining the signal-to-noise ratio (S/N) of the detection system. An optimization procedure of its amplitude and frequency is proposed. Although the SIN must be determined by introduction of actual samples, the operating conditions can be optimized merely by changing the signal parameters and by using a mathematical procedure. Thus, an easy and fast optimization routine can be carried out. Mathematical and instrumental backgrounds are discussed, and experimental support of the techniques effectiveness is presented.

Visual perception of extent and the geometry of visual space.

The question of how perceived extents are related to the corresponding physical extents is a very old question that has not been satisfactorily answered. The common model is that perceived extent is proportional to the product of image size and perceived distance. We describe an experiment that shows that perceived extents are substantially larger than this model predicts. We propose a model that accounts for our results and a large set of other results. The principal assumption of the model is that, in the computation of perceived extent, the visual angle signal undergoes a magnifying transform. Extent is often perceived more accurately than the common model predicts, so the computation is adaptive. The model implies that, although the perception of location and the perception of extent are related, they not related by Euclidean geometry, nor by any metric geometry. Nevertheless, it is possible to describe the perception of location and extent using a simple model.

A two-process theory of the response to size and distance

Evidence for a two-process theory of the observer’s visual judgment of size and distance is summarized and evaluated. The primary process, as expressed by the size-distance invariance hypothesis (SDIH), concerns the interrelation of perceived size (S’) and perceived distance (D’), independent of information derived from memory or suggestion. The secondary process involves information regarding size (from memory or suggestion) not contained in the immediate visual stimulus. If the primary and secondary sources of size information differ, the object is seen as off-sized. This off-sized perception can be used to modify the direct report of the distance of the object. In the case of the casual suggestion of size, the off-sized judgment produces a nonperceptual (cognitive) report of distance (Gogel, 1981b). In the case of the memory of the size of a familiar object, some of the effect on the direct report of perceived distance is perceptual, but most is cognitive (Gogel, 1976). In the case of optical expansion, the effect of off-sized judgments on distance responses produces a clear modification of perceived distance (Swanston & Gogel, 1986). The experimental distinction between primary and secondary processes is facilitated by comparing measures of perceived distance obtained from direct procedures (e.g., verbal reports of distance) with those obtained from indirect procedures (e.g., the head motion procedure). The former (direct) methods reflect both primary and secondary sources of information. The latter (indirect) methods are sensitive only to primary sources. The significance of the two-process theory for the specification of the SDIH and the explanation of other visual phenomena is discussed.

Familiar size and the theory of off-sized perceptions

The role of familiar size in the visual judgment of size and distance was investigated using reduced conditions of observation and instructions that called for either objective or apparent size and distance judgments. Each observer was presented with one object at one distance (56, 107, or 149 cm). This object, which was of constant physical size, was either a normal-sized playing card or a blank rectangle of the same size as the playing card. Distance responses were verbal and size responses were tactual. For the blank rectangle, reported distance remained constant, whereas judged size decreased as physical distance increased for both objective and apparent instructions. For the playing card, reported distance increased as physical distance increased for both objective and apparent instructions. The judged size for the playing card, however, remained constant with objective instructions but decreased with apparent instructions as the physical distance increased. This pattern of results is consistent with the theory that, to a substantial degree, familiar size contributes to spatial responses by means of a cognitive process based upon familiar objects’ appearing as smaller or larger than normal. Under conditions in which the familiar objects are normal in size (as in the present experiment), this process acts to correct a direct response to distance for any errors that might be present in the perception of distance.

Conductivity detection of aliphatic alcohols in micellar electrokinetic chromatography using an oscillometric detector.

Although conductivity is usually applied to detect ionic species in capillary electrophoresis (CE), nonionic species can also be detected by their indirect effects on the conductivity of the running electrolyte. This approach was used for detection of aliphatic alcohols in micellar electrokinetic chromatography (MEKC) with an oscillometric detector. Although the detector operates at 600 kHz, for the range of electrolyte concentration used in CE, the response is mainly due to variations of conductivity. A 50 mM phosphate and 50 mM SDS solution was used as running electrolyte and as the solvent for mixtures of some isomers of propanol, butanol, and pentanol. A set of negative peaks was obtained and assigned to the components by spiking the samples. The limits of detection (LOD) ranged from 2.1 mM for 2-methyl-2-propanol to 5.3 mM for 1-pentanol. Due to the high affinity for the interior of the micelles, 1-hexanol could not be easily-detected, but by the addition of 10% methanol to the running electrolyte it was possible. For this electrolyte, the LOD was improved, ranging from 0.8 mM for 2-methyl-2-propanol to 1.5 mM for 1-pentanol. Calibration plots were linear up to 40 mM at least. These results indicate that conductivity may be useful for detection of nonionic species in CE, especially when optical methods can not be conveniently applied.

Psicologia positiva e o estudo do bem-estar subjetivo

The proposal of the this paper was to present the emerging of the Positive Psychology as a new important field of the contemporary Psychology, in a moment when new studies has focused the understanding of human strengths and values. One of its main components gave special attention, subjective well-being, also known as happiness. Searching to elucidate the involved aspects in the study of subjective well-being, this article looked for to approach some of its most important correlates. The best agreement of the involved factors with the sprouting of positive and negative emotions allows a better understanding of the human beings condition up against the adversities.

Comparative Study of Analgesic Effectiveness Using Three Different Anesthetic Techniques for Intravitreal Injection of Bevacizumab

BACKGROUND AND OBJECTIVE To compare the analgesic effectiveness and aesthetic appearance associated with topical, subconjunctival, and peribulbar anesthesia for intravitreal bevacizumab injection. PATIENTS AND METHODS Sixty consecutive patients undergoing their first intravitreal bevacizumab injection were randomized to receive one of three forms of anesthesia: proxymetacaine eye drops, subconjunctival injection of 2% xylocaine, and peribulbar injection of 2% xylocaine. Pain associated with the intravitreal injection and with the entire procedure (including anesthesia administration) was recorded using a Visual Analog Scale 15 minutes after intravitreal injection. Anterior segment evaluation was performed 24 hours after injection to measure the number of clock hours of subconjunctival hemorrhage. RESULTS Median injection-related pain score was significantly lower in the peribulbar group compared with the topical and subconjunctival groups (P < .05). Median entire procedure pain score was significantly higher in the peribulbar group compared with the topical and subconjunctival groups (P < .05). The median extent of subconjunctival hemorrhage was significantly lower in the topical group compared with the other groups (P < .05). CONCLUSION Among the three anesthetic techniques, peribulbar anesthesia was associated with greater effectiveness in controlling injection-related pain but was least effective in controlling entire procedure pain. There was no significant difference in pain scores between the topical and subconjunctival groups, and topical anesthesia was associated with less subconjunctival hemorrhage.

Uso e aplicação da metodologia psicofísica na pesquisa em enfermagem

Conceitos e fenomenos subjetivos, tais como atitudes sociais, opinioes e processos de julgamentos tem sido dificeis de serem mensurados acuradamente. Muitos conceitos ou variaveis em Enfermagem sao de natureza subjetiva. Como nas ciencias sociais, a profissao de enfermagem enfrenta muitos problemas para obter medidas precisas de tais variaveis. A metodologia psicofisica, especialmente os procedimentos de estimacao de magnitude e de emparelhamento intermodal, desenvolvidos na psicofisica sensorial e sendo atualmente usados nas ciencias sociais, tem se mostrado promissora em Enfermagem como um instrumento para escalonar fenomenos subjetivos. O proposito deste trabalho e descrever essas tecnicas de mensuracao, o paradigma teorico sobre o qual elas sao baseadas e tambem varios estudos de âmbito social, clinico e de enfermagem, nos quais foram utilizadas essas estrategias de mensuracao.

Cientometria: a métrica da ciência

Scientometrics is defined as the study of the measurement and quantification of scientific and technological progress and much the research is bibliometric in nature. Scientometric has a wide potential applicability. Government and research institutions have expressed interest in applying this knowledge of scientific growth to the management of science.. Ultimately, scientometrics may be used to help nations make decisions on what areas of research need funding. The citation analyses have become an increasingly significant source of information for historians, sociologists, and other researchers studying the evolution of science. This article focuses on how citation indexes make it possible to trace the background and development of discoveries as well as to assess the credit that publishing scientists assign to particular discoverers. This kind of analysis complements the opinions and judgments of experts (peer review), thus providing objective and useful tools for evaluating the results of scientific activity.

A dor como um problema psicofísico

BACKGROUND AND OBJECTIVES: Pain quantification faces special difficulties. They appear due to the obvious association of pain to a set of emotional, motivational and cultural factors. However, pain measurement is essential to evaluate and treat its effects. This study aimed at showing that psychophysical methods might be adequately used to measure both clinical and experimental pain. CONTENTS: In addition, the methodology may be useful to analyze pain mechanisms, analgesia, methodological biases inherent to pain verbal records, and to dissociate sensory and cognitive components from pain sensation/perception. CONCLUSION: The psychophysical methodology may be a trustworthy and valid measurement of the fifth vital sign, which is pain, in all its dimensions.