Preliminary data for performance in hue ordering tests during pregnancy

The visual system of women changes during pregnancy. Few reports have addressed the effects of pregnancy on color vision. We aimed to compare the color vision of women in the first, second, and third trimesters of pregnancy. Fifty women were divided into first (n=10), second (n=10), third trimester pregnancy groups (n=10), and non-pregnant group (n=20). We used the Farnsworth D15 and Lanthony desaturated D15 (D15d) tests. The hue ordering quantified the amount of error (C-index) and the chromatic selectivity of the errors (S-index). Bland-Altman analysis was applied to the hue ordering data. No difference was found for Farnsworth D15 test results obtained from the pregnant groups and the non-pregnant group (P<0.0083). For the Lanthony D15 desaturated test, the third trimester pregnant group had higher C-index and S-index than non-pregnant women and first-trimester pregnant women (P<0.0083). The Bland-Altman analysis showed that the limits of agreement increased as pregnancy advanced, and the errors were biased to the D15d test. In this study, color vision was impaired during pregnancy. Color vision evaluation could be used as an indicator of the functional status of the central vision during pregnancy.

Chromatic spatial contrast sensitivity estimated by visual evoked cortical potential and psychophysics

The purpose of the present study was to measure contrast sensitivity to equiluminant gratings using steady-state visual evoked cortical potential (ssVECP) and psychophysics. Six healthy volunteers were evaluated with ssVECPs and psychophysics. The visual stimuli were red-green or blue-yellow horizontal sinusoidal gratings, 5° × 5°, 34.3 cd/m2 mean luminance, presented at 6 Hz. Eight spatial frequencies from 0.2 to 8 cpd were used, each presented at 8 contrast levels. Contrast threshold was obtained by extrapolating second harmonic amplitude values to zero. Psychophysical contrast thresholds were measured using stimuli at 6 Hz and static presentation. Contrast sensitivity was calculated as the inverse function of the pooled cone contrast threshold. ssVECP and both psychophysical contrast sensitivity functions (CSFs) were low-pass functions for red-green gratings. For electrophysiology, the highest contrast sensitivity values were found at 0.4 cpd (1.95 ± 0.15). ssVECP CSF was similar to dynamic psychophysical CSF, while static CSF had higher values ranging from 0.4 to 6 cpd (P < 0.05, ANOVA). Blue-yellow chromatic functions showed no specific tuning shape; however, at high spatial frequencies the evoked potentials showed higher contrast sensitivity than the psychophysical methods (P < 0.05, ANOVA). Evoked potentials can be used reliably to evaluate chromatic red-green CSFs in agreement with psychophysical thresholds, mainly if the same temporal properties are applied to the stimulus. For blue-yellow CSF, correlation between electrophysiology and psychophysics was poor at high spatial frequency, possibly due to a greater effect of chromatic aberration on this kind of stimulus.

Eficácia do glyphosate e 2, 4-d no controle de Commelina villosa / Efficacy of glyphosate and 2, 4-D in control of Commelina villosa

O objetivo do presente trabalho foi avaliar a eficácia de glyphosate e 2,4-D, isolados e em mistura, no controle de Commelina villosa. Foram estudadas duas metodologias de avaliação de absorção de herbicidas em oito intervalos de tempo para a lavagem (simulando chuva após a aplicação) e corte (simulando abortamento, como estratégia de defesa) das folhas: 2, 4, 6, 8, 12, 24 e 48 horas após a aplicação dos herbicidas, além de um tratamento sem lavagem ou corte das folhas, em delineamento experimental inteiramente casualizado com quatro repetições, dispostos em um esquema fatorial 3 x 7 + 1 (três herbicidas x sete períodos – horas após a aplicação). Os herbicidas e doses testados foram: glyphosate (1.440 g ha-1), 2,4-D (720 g ha-1) e a mistura glyphosate + 2,4-D (1.080 + 720 g ha-1). A simulação de chuva interferiu de forma negativa no controle das plantas com o herbicida glyphosate. O controle com o herbicida 2,4-D foi influenciado apenas no período de 2 horas. Os períodos de simulação de chuva não influenciaram no controle das plantas com a mistura de glyphosate + 2,4-D. Para o estudo com corte das folhas tratadas, todos os tratamentos independente do período para corte das folhas foram influenciados de forma negativa no controle, sendo que as plantas apresentaram rebrotas quando tratadas com o herbicida 2,4-D isolado.

Efficacy of glyphosate and 2,4-d in the control of Commelina Villosa. The aim of this study was to evaluate the efficacy of glyphosate and 2,4-D alone and in combination, in the control of Commelina villosa. We studied two methodologies for evaluating herbicide absorption in eight time intervals for washing (simulating rainfall after application) and cutting of leaves (simulating abortion as a defense strategy): 2, 4, 6, 8, 12, 24 and 48 hours after herbicide application, and a treatment without washing or cutting the leaves in a completely randomized design with four replications in a 3 x 7 + 1 factorial design (three herbicides x seven periods – hours after application). Herbicides and doses tested were: glyphosate (1,440 g ha-1), 2,4-D (720 g ha-1) and a mixture of glyphosate + 2,4-D (1,080 + 720 g ha-1). The simulation of rain interfered negatively in the plant control with glyphosate. The control with the herbicide 2,4-D was affected only for the period of 2 hours. Periods of rain simulation did not influence the control of plants with a mixture of glyphosate + 2,4-D. For the study with the cutting of treated leaves, all treatments regardless of the period of cutting the leaves were influenced negatively in terms of plant control, the plants showing regrowth when treated with 2,4-D alone.

Glyphosate and imazamox translocation in water hyacinth plants / Translocação dos herbicidas glyphosate e imazamox em plantas de aguapé

Eichhornia crassipes is one of the main weeds found in aquatic environments, being undesirable for many activities. The aim of this study was to evaluate the translocation of glyphosate and imazamox in E. crassipes. Eight intervals were studied for cutting leaves that received herbicides: 2, 4, 6, 8, 12 and 24 hours after application (HAA), and a treatment with no cutting (untreated). The glyphosate dose was 2,160 g a.e. ha-1 (commercial product - Rodeo) + 0.5% v v-1 Aterbane adhesive spreader and imazamox at 290.4 g i.a. ha-1 (commercial product - Clearcast). The treatments were installed in a completely randomized design with four replications. Glyphosate showed a bad control for all the periods of leaf cutting. The imazamox did not provide control within 12 HAA, while from 24 HAA onward the control was effective. There was not a great mobility of the glyphosate molecule in water hyacinth plants, a period above 24 hours being needed for a satisfactory translocation. For imazamox at least 24 hours were needed after herbicide application for the translocation to occur along with subsequent control.

Entre as diversas plantas daninhas encontradas em ambientes aquáticos, a Eichhornia crassipes é uma das principais, sendo espécie indesejável para muitas atividades. O objetivo deste trabalho foi avaliar a translocação de glyphosate e imazamox em plantas de E. crassipes. Foram estudados oito intervalos de tempo para o corte das folhas que receberam os herbicidas: 2, 4, 6, 8, 12 e 24 horas após a aplicação (HAA) dos produtos, além de um tratamento sem corte das plantas (testemunha). Utilizaram-se glyphosate na dose de 2.160 g e.a. ha-1 (produto comercial - Rodeo) + 0,5% v v-1 do espalhante adesivo aterbane e imazamox na dose de 290,4 g i.a. ha-1 (produto comercial - Clearcast). Os tratamentos foram instalados em um delineamento experimental inteiramente casualizado com quatro repetições. O glyphosate apresentou um controle insatisfatório quando realizado os cortes das folhas em todos os períodos avaliados. O herbicida imazamox não proporcionou controle em até 12 HAA, enquanto que a partir de 24 HAA do herbicida o controle foi eficiente. Não houve uma grande mobilidade da molécula de glyphosate nas plantas de aguapé, sendo necessário um período superior a 24 horas para uma translocação satisfatória. Já para o imazamox um tempo de mínimo de 24 horas após a aplicação do herbicida foi suficiente para que ocorresse a translocação e um posterior controle.

Comparison of the reliability of multifocal visual evoked cortical potentials generated by pattern reversal and pattern pulse stimulation

This study compared the effectiveness of the multifocal visual evoked cortical potentials (mfVEP) elicited by pattern pulse stimulation with that of pattern reversal in producing reliable responses (signal-to-noise ratio >1.359). Participants were 14 healthy subjects. Visual stimulation was obtained using a 60-sector dartboard display consisting of 6 concentric rings presented in either pulse or reversal mode. Each sector, consisting of 16 checks at 99% Michelson contrast and 80 cd/m² mean luminance, was controlled by a binary m-sequence in the time domain. The signal-to-noise ratio was generally larger in the pattern reversal than in the pattern pulse mode. The number of reliable responses was similar in the central sectors for the two stimulation modes. At the periphery, pattern reversal showed a larger number of reliable responses. Pattern pulse stimuli performed similarly to pattern reversal stimuli to generate reliable waveforms in R1 and R2. The advantage of using both protocols to study mfVEP responses is their complementarity: in some patients, reliable waveforms in specific sectors may be obtained with only one of the two methods. The joint analysis of pattern reversal and pattern pulse stimuli increased the rate of reliability for central sectors by 7.14% in R1, 5.35% in R2, 4.76% in R3, 3.57% in R4, 2.97% in R5, and 1.78% in R6. From R1 to R4 the reliability to generate mfVEPs was above 70% when using both protocols. Thus, for a very high reliability and thorough examination of visual performance, it is recommended to use both stimulation protocols.