Insecticide resistance, associated mechanisms and fitness aspects in two Brazilian Stegomyia aegypti (= Aedes aegypti) populations.

In Brazil, insecticide resistance in Stegomyia aegypti (= Aedes aegypti) (Diptera: Culicidae) populations to pyrethroids and to the organophosphate (OP) temephos is disseminated. Currently, insect growth regulators (IGRs) and the OP malathion are employed against larvae and adults, respectively. Bioassays with mosquitoes from two northeast municipalities, Crato and Aracaju, revealed, in both populations, susceptibility to IGRs and malathion (RR95 ≤ 2.0), confirming the effectiveness of these compounds. By contrast, temephos and deltamethrin (pyrethroid) resistance levels were high (RR95 > 10), which is consistent with the use of intense chemical control. In Crato, RR95 values were > 50 for both compounds. Knock-down-resistant (kdr) mutants in the voltage-gated sodium channel, the pyrethroid target site, were found in 43 and 32%, respectively, of Aracaju and Crato mosquitoes. Biochemical assays revealed higher metabolic resistance activity (esterases, mixed function oxidases and glutathione-S-transferases) at Aracaju. With respect to fitness aspects, mating effectiveness was equivalently impaired in both populations, but Aracaju mosquitoes showed more damaging effects in terms of longer larval development, decreased bloodmeal acceptance, reduced engorgement and lower numbers of eggs laid per female. Compared with mosquitoes in Crato, Aracaju mosquitoes exhibited lower OP and pyrethroid RR95 , increased activity of detoxifying enzymes and greater effect on fitness. The potential relationship between insecticide resistance mechanisms and mosquito viability is discussed.

Detection and Distribution of V1016Ikdr Mutation in the Voltage-Gated Sodium Channel Gene in Aedes aegypti (Diptera: Culicidae) Populations From Sergipe State, Northeast Brazil.

Aedes aegypti (L.) resistance to pyrethroids was recorded in Brazil few years after its introduction as the adulticide in the National Dengue Control Program campaigns. Altered susceptibility to pyrethroids had been reported in the state of Sergipe, northeast Brazil, through biological assays, even before its use against Ae. aegypti in the state. Metabolic and target-site resistance mechanisms were also revealed in samples from Aracaju, the capital of Sergipe. Herein, we investigated the presence and distribution of the kdr mutation V1016Ikdr in Ae. aegypti populations from different municipalities of the state. Aedes aegypti eggs were collected from seven municipalities located in areas showing different climatic types and infestation levels. Approximately 20 Ae. aegypti females from each municipality (total of 135 subjects) were individually submitted to allele-specific polymerase chain reaction (AS-PCR) for the 1016 site of the voltage-gated sodium channel (NaV). The V1016Ikdr mutation was found in subjects from all the municipalities under study with a high frequency of heterozygotes in several locations. Homozygous recessive subjects (resistant kdr genotype) were found only in one municipality. The results suggest a wide distribution of the V1016Ikdr mutation in the northeast Brazil, which indicates urgent need for monitoring the effectiveness of the pyrethroids currently used for vector control.

Nanocomposite metal amorphous-carbon thin films deposited by hybrid PVD and PECVD technique.

Carbon based films can combine the properties of solid lubricating graphite structure and hard diamond crystal structure, i.e., high hardness, chemical inertness, high thermal conductivity and optical transparency without the crystalline structure of diamond. Issues of fundamental importance associated with nanocarbon coatings are reducing stress, improving adhesion and compatibility with substrates. In this work new nanocomposite coatings with improved toughness based in nanocrystalline phases of metals and ceramics embedded in amorphous carbon matrix are being developed within the frame of a research project: nc-MeNxCy/a-C(Me) with Me = Mo, Si, Al, Ti, etc. Carbide forming metal/carbon (Me/C) composite films with Me = Mo, W or Ti possess appropriate properties to overcome the limitation of pure DLC films. These novel coating architectures will be adopted with the objective to decrease residual stress, improve adherence and fracture toughness, obtain low friction coefficient and high wear-resistance. Nanocomposite DLC's films were deposited by hybrid technique using a PVD-Physically Vapor Deposition (magnetron sputtering) and Plasma Enhanced Chemical Vapor Deposition (PECVD), by the use of CH4 gas. The parameters varied were: deposition time, substrate temperature (180 degrees C) and dopant (Si + Mo) of the amorphous carbon matrix. All the depositions were made on silicon wafers and steel substrates precoated with a silicon inter-layer. The characterisation of the film's physico-mechanical properties will be presented in order to understand the influence of the deposition parameters and metal content used within the a-C matrix in the thin film properties. Film microstructure and film hybridization state was characterized by Raman Spectroscopy. In order to characterize morphology SEM and AFM will be used. Film composition was measured by Energy-Dispersive X-ray analysis (EDS) and by X-ray photoelectron spectroscopy (XPS). The contact angle for the produced DLC's on silicon substrates were also measured. Thin film adherence was studied by micro-scratch test. Residual stresses in the produced coatings will be analysed by bending technique.

Novel nanocomposite coatings with dispersed organic nanoparticles for solar absorbers.

A natural pigment (Anthocyanin extracted from Sambucus nigra L. fruit) was incorporated by dipping sputtered titanium oxide films into a pigment solution. The pigment solution has red colour and an absorption peak located in the wavelength range of 520 to 540 nm. Titanium oxide thin films were prepared by reactive DC magnetron sputtering and reactive pulsing DC magnetron sputtering from a Titanium target in O2 + Ar atmosphere onto glass slides. Pigment incorporation in thin films was found dependent of both morphology and composition, which depends on deposition parameters, like pulsing frequency and oxygen flow rate. The incorporation of this pigment in TiOx thin films increases the final solar absorption and decreases the final average roughness of these films. The effect in solar absorption is higher in films prepared by DC and pulsed DC at pulsing frequency of 200 kHz.

Assessment of pulmonary function in patients before and after laparoscopic and open esophagogastric surgery.

BACKGROUND: Laparoscopy is a technique used in various surgical procedures. Few studies in the literature compare stress between laparoscopic and open surgery used for esophagogastric surgical procedures. Pulmonary function is known to be significantly affected in open surgeries, increasing postoperative morbidity and mortality. The current study aimed to assess pulmonary function in patients before and after open and laparoscopic esophagogastric surgery. METHODS: For this study, 75 patients were divided into two groups: 50 patients undergoing laparoscopy and 25 patients undergoing open surgery. The following parameters were determined by spirometry before and after surgery: forced expiratory volume in the first second (FEV(1)), forced vital capacity (FVC), and forced expiratory flow in the midexpiratory phase (FEF(25-75%)). RESULTS: A decrease in FEV(1,) FVC, and FEF((25-75%)) was observed in the two groups on postoperative days 2, 3, and 4, as compared with the preoperative period. Likewise, FEV(1) and FVC showed a significant reduction on postoperative days 2, 3, and 4 in the patients who underwent to open surgery, but only on the day 2 in those who underwent to laparoscopic surgery. A significant decrease in FEF((25-75%)) was observed only on postoperative day 2 in the group that underwent open surgery. Significant differences in FEV(1) between the groups were observed on postoperative days 2, 3, and 4. No significant difference in FVC was noted between the groups, and a difference in FEF((25-75%)) was observed only on postoperative day 4. CONCLUSIONS: Postoperative pulmonary dysfunction was more important for the patients undergoing open surgery than for those undergoing laparoscopic surgery.

Smooth pursuit of small-amplitude sinusoidal motion.

Subjects used smooth eye movements to track small-amplitude sinusoidal target motions. Target frequencies (0.05 to 5 Hz) and amplitudes (1.9 to 30 min of arc) were in the range of those found in the retinal image during fixation of a stationary target while the head is not artificially supported. Smooth pursuit was poor at high target frequencies in several ways: Large uncompensated drifts were observed for target frequencies between 1 and 4 Hz. The drifts were superimposed upon oscillations of the eye in response to the target motion. Mean retinal-image speeds were higher than retinal-image speeds during slow control (smooth eye movements with stationary targets) for target frequencies above 0.5 Hz. Mean retinal-image speeds were as high as target speed for target frequencies above 3 Hz. The ratio of eye speed to target speed decreased as target frequency and amplitude increased. The dependence on amplitude could be reduced and often eliminated by computing an adjusted ratio in which a constant (approximately equal to the mean speed of slow control) was subtracted from eye speed before dividing by target speed. Adjusted ratios declined for frequencies above 0.5 to 1 Hz and did not depend on amplitude. These results show that the response of the smooth-pursuit subsystem to target motion above 0.5 Hz is poor, even though the velocity and the acceleration of th motions are low. Models of smooth pursuit in which the response of the eye depends exclusively on the velocity, acceleration, or position of the target do not account for our results.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of expectations on slow oculomotor control--IV. Anticipatory smooth eye movements depend on prior target motions.

Prior work had shown that smooth eye movements depend both on the motion of the target on the retina and on the subject's expectations about future target motion (Kowler and Steinman, 1979a,b). Effects of expectation cannot be eliminated by making target motions unpredictable (Kowler and Steinman, 1981). The experiment reported here shows that effects of expectations on smooth eye movement depend in a lawful way on the history of prior target motions. Anticipatory smooth eye movements (involuntary drifts in the direction of future target motion) were measured while subjects fixated a stationary target that was expected to step in an unpredictable direction (right or left). Anticipatory smooth eye movement velocity depended on the sequence of steps in prior trials, e.g. velocity was faster to the right when the prior steps were to the right. The influence of prior steps diminished the further back into the past the step occurred. Sequential dependencies were also observed for the saccades used to track the target steps. Anticipatory smooth eye movement velocity was predicted by a two-state Markov model developed by Falmagne et al. (1975) for similar sequential dependencies observed in a manual reaction-time task (button-pressing). The model uses the prior sequence of target motions to predict the subject's expectation, and assumes that the expectation determines anticipatory smooth eye movement velocity. The fit of the model to the data was good which shows that taking expectations into account is both necessary and feasible. Taking expectations into account, quantitatively, allows accurate predictions about smooth eye movement velocity when target motions are unpredictable.

Compensatory eye movements during active and passive head movements: fast adaptation to changes in visual magnification.

Rotational eye and head movements were recorded with great precision with scleral and cranial search coils in a rotating magnetic field. Compensatory eye movements were recorded in light and darkness during active as well as passive head movements in the frequency range 0.33-1.33 Hz. From the recorded, nominal gaze movements the effective gaze was reconstructed taking into account magnification or reduction factors of corrective spectacles. Effective gain was calculated as the ratio between the velocities of the effective corrective eye movements and the head movements. In the light, effective gain of compensatory eye movements during active head motion was mostly between 0.97 and 1.03. It was never precisely unity and differed systematically between subjects and between the two eyes of each subject. During passive head motion in the light, gain was lower by about 3% than during active motion. During active head movement in the dark, gain was mostly between 0.92 and 1.00; values were about 5% lower than during active motion in the light. During passive head movement in the dark, gain was about 13% lower than during active motion, and the variability of the oculomotor response increased. Adaptation of these base-line conditions was induced by fitting the subjects with magnifying or reducing spectacles for periods of 40 min to 24 h. The largest required change in amplitude of eye movements was 36%. When active head movements were made, the amplitude of compensatory eye movements in the light as well as in the dark adjusted rapidly. Most of the adaptation of the vestibulo-ocular reflex in the dark was completed in about 30 min. This rate is much faster than that found in previous experiments requiring larger adaptive changes. Differential adaptation to unequal demands for the two eyes proved to be very hard or impossible. In a mild conflict situation the system adjusted to an intermediate level, distributing the error symmetrically between the eyes. When the discrepancy was large, the adaptive process of both eyes was controlled by the one eye which provided the most meaningful information. It is concluded that the system generating compensatory eye movements performs best during active rather than passive head movements, and that adaptation to moderate changes in optimal gain are made very rapidly.

Eye movements of preschool children.

Accurate recordings of eye movements of children 4 and 5 years old show that their eye movements differed from those of adults. During maintained fixation, saccades were large (1 degree to 2 degrees) and smooth eye movement speeds were high (45 minutes of arc per second). Saccade latencies were highly variable during target step tracking. Smooth pursuit latencies were longer than those of adults. These hitherto unknown characteristics limit a child's ability to use eye movements to acquire visual information.

The precision of gaze. A review.

This paper reviews advances in our knowledge about the stability of the human being's line of sight while fixating objects stationary with respect to himself. Recent technological developments made it possible to measure gaze with a high degree of accuracy when the head was free of artificial support. Measurements made with the head free while the subject sat, as still as possible, show that gaze is half as stable as when the head is held rigidly. Precision deteriorates by an additional factor of five when the head is moved actively or passively within a range of natural physiological frequencies and amplitudes. Fixation errors and retinal image motions associated with such imprecision of gaze under natural conditions would not be expected to degrade monocular vision in light of current psychophysical evidence. Binocular fixation errors and differences in retinal image motions in each of the eyes, associated with imprecision of vergence under natural conditions, cannot, however, be reconciled with current psychophysical knowledge of binocular vision attained thus far only under artificial conditions.