Search results for "structures"
showing 10 items of 4815 documents
Stable polymorphism for mutant eye colour geues in populations of Drosophila melanogaster in two different media
1988
In previous work analyzing variability of eye colour alleles existing in natural populations of D. melanogaster, it was observed that the number of females heterozygous for some eye colour alleles was greater in a wine cellar population than in populations outside this cellar. In order to determine which mechanisms caused these eye colour alleles to be favored in the heterozygotes, the changes in the frequency of four eye colour alleles frequently seen in the cellar population (se77o, sf77m, cd77o and multichromosomal 77o) was studied in artificial populations. Two different culture media, one supplemented with 10% ethanol and the other without ethanol were used. It was found that each of t…
Effect of two different tooth bleaching techniques on microhardness of giomer
2016
Background Tooth bleaching is a safe and conservative treatment modality to improve the esthetic appearance of discolored teeth. One of the problems with the use of bleaching agents is their possible effect on surface microhardness of resin-based materials. The present study was carried out to evaluate the effect of in-office and at-home bleaching on surface microhardness of giomer. Material and Methods Seventy-five disk-shaped giomer samples (Beautifil II) were prepared and cured with a light-curing unit. The samples were randomly assigned to three groups (n=25). In group 1 (control), the samples were stored in distilled water for 14 days. The samples in groups 2 and 3 underwent a bleachin…
Gender differences in implicit and explicit anxiety measures
2004
Abstract Explicit measures assess introspectively accessible self-descriptions and evaluations. In contrast, implicit measures assess introspectively inaccessible processes that operate outside of awareness. While women consistently yield higher scores on explicit anxiety measures, there are to date no studies available that examine gender differences in implicit anxiety measures. To analyse this topic, we used the Implicit Association Test (Study 1, N =248) and the Emotional Stroop task (Study 2, N =121) as implicit anxiety measures and a standard trait questionnaire as explicit anxiety measure. As expected, women scored higher on the explicit anxiety test. Women also yielded higher anxiet…
Malestar emocional y percepción de amenaza en familiares de personas afectadas por COVID-19
2021
Los familiares de personas afectadas por la COVID-19 pudieron experimentar mayor impacto emocional durante el confinamiento, más aún si se tenía una imagen muy amenazante del COVID-19. El objetivo fue analizar la relación entre la psicopatología y la percepción de amenaza en familiares de personas afectadas por COVID-19. Participaron 50 familiares de personas afectadas por COVID-19 (84% mujeres), de entre 20 y 63 años (M=36,88; DT=12,73). Se evaluó la psicopatología (SCL-90-R; Derogatis, Lipman y Covi, 1973) y la percepción de amenaza del COVID (BIP-Q5; Pérez-Fuentes, Molero, Oropesa et al., 2020). Observamos una afectación emocional y una percepción de amenaza moderadas. Quienes tenían enf…
Visual learning in Drosophila: Application on a roving robot and comparisons
2011
Visual learning is an important aspect of fly life. Flies are able to extract visual cues from objects, like colors, vertical and horizontal distributedness, and others, that can be used for learning to associate a meaning to specific features (i.e. a reward or a punishment). Interesting biological experiments show trained stationary flying flies avoiding flying towards specific visual objects, appearing on the surrounding environment. Wild-type flies effectively learn to avoid those objects but this is not the case for the learning mutant rutabaga defective in the cyclic AMP dependent pathway for plasticity. A bio-inspired architecture has been proposed to model the fly behavior and experi…
Tear production and intraocular pressure values in clinically normal eyes of whooper swans (Cygnus cygnus)
2018
The objective of this study was to determine the normal range of tear production and values of intraocular pressure (IOP) in clinically normal eyes of whooper swans (Cygnus cygnus). A total of 86 birds: 81 cygnets (6-10 weeks old) and 5 moulting – adult swans (3-6 years old) were examined in this study. Both eyes of all birds underwent a complete ophthalmic examination, including evaluation of tear production with the phenol red thread test (PRTT) and the assessment of the IOP by rebound tonometry, employing the TonoVet® device. The mean ± standard deviation of PRTT values were as follows: all cygnets (81) 22.59±3.48 mm/15s, male cygnets (45) 22.64±3.54 mm/15s, female cygnets (36) 22.53±3.4…
Effect of fixation target on the contrast sensitivity in the foveal and parafoveal area
2017
Purpose To determine the influence on the contrast sensitivity when the stimulus contains a fixation target in two retinal locations, foveal and parafoveal. Methods Four young adults with 0.0 logMar acuity participated in this study. The stimulus was based on vertical sinusoidal gratings masked by a circular (for foveal area) or a ring (for parafoveal area). To increase the luminance resolution of the display a bit-stealing technique was used. Four different sets of stimuli were generated, two for exploring the foveal sensitivity and two for the parafoveal area. The difference between the sets designed for the same area was the presence, or absence, of a fixation target (a white cross) in t…
Mesoporous silica microparticles gated with a bulky azo derivative for the controlled release of dyes/drugs in colon.
2018
[EN] Mesoporous silica microparticles were prepared, loaded with the dye safranin O (M-Saf) or with the drug budesonide (M-Bud) and capped by the grafting of a bulky azo derivative. Cargo release from M-Saf at different pH values (mimicking those found in the gastrointestinal tract) in the absence or presence of sodium dithionite (a reducing agent mimicking azoreductase enzyme present in the colon) was tested. Negligible safranin O release was observed at pH 6.8 and 4.5, whereas a moderate delivery at pH 1.2 was noted and attributed to the hydrolysis of the urea bond that linked the azo derivative onto the external surface of the inorganic scaffold. Moreover, a marked release was observed w…
Ageing via sexual perception is a by-product of male adaptive plasticity inDrosophila melanogaster
2021
ABSTRACTSensory perception of environmental cues can dramatically modulate ageing across distant taxa. For example, maleDrosophila melanogasterage faster if they perceive female cues but fail to mate (ageing via sexual perception). This finding has been a breakthrough for our understanding of the mechanisms of ageing, yet we ignore how and why such responses have evolved. Here, we usedD. melanogasterto ask whether ageing via sexual perception may be a by-product of plastic adaptive responses to female cues, and found that while long-term sexual perception leads to reproductive costs, short-term perception increases male lifetime reproductive success in a competitive environment. Simulations…
The effect of staining and bleaching on the color of two different types of composite restoration
2021
Background Long term success of composite restorations depends greatly on their color stability and esthetic appearance. This study aimed to assess the effects of commonly consumed beverage and bleaching on the color of composite restoration. Material and Methods Two resin composite were used Filtek™ Z350 XT (3M/ESPE) and Briliant EverGlow (Coltene). Fifteen discs were made from each resin composite then baseline color measurements were made. The specimens divided into 3 groups (n=5) according to the storage solution. The storage solutions that used in this study are distilled water, tea and coffee. The specimens were stored in the solutions for 3h/day for 40 days and then second color meas…