Critical Flicker Frequency in a Harp Seal, \u3ci\u3ePagophilus groenlandicus\u3c/i\u3e (Erxleben, 1777)

Critical flicker frequency (CFF) in a free-swimming harp seal (Pagophilus groenlandicus) was investigated using behavioral techniques. The resulting CFF versus intensity contour indicates a definite rod-cone break, confirming a duplex photoreceptor population whose presence had not been observed in previous morphological reports

Influence of different kind of clothing material on selected cardiovascular, respiratory and psychomotor parameters during moderate physical exercise

Objectives: The aim of the experiment was to analyze the influence that the clothing material may have on human physiology and thermal comfort both at rest and physical effort to answer the question which fabric is better, a natural or a synthetic one. Materials and Methods: We measured some psychomotor parameters: critical flicker frequency (CFF), reaction time to auditory/visual stimuli (RT), concentration of attention (CA); cardiovascular parameters: blood pressure (BP), heart rate (HR) and respiratory parameters: tidal volume (VT), minute ventilation (VE), oxygen consumption (VO2), carbon dioxide output (VCO2), respiratory exchange ratio (RER) in human volunteers before, during and after physical effort. The subjects performed a 15-min treadmill test on treadmill wearing clothes made of two different materials: 100% coarse wool and 100% acrylic. An interview was conducted directly before the exercise test to assess the subjects' general mood and wellbeing on that day. Besides, before and after the test, the subjects in their own words described the sensation they felt with respect to the physiological comfort of particular clothing. Results: The results showed that wearing clothes made of different fabrics had some influence on the cardiovascular and respiratory parameters during physical effort but it did not have any effect on the psychomotor skills. The perception of physiological comfort by the subjects wearing coarse wool or acrylic depended on their physiological state and differed at rest and after the physical effort. Conclusions: The course of physiological processes depends on the kind of clothing a given person is wearing. It is not possible to clearly define which of the two clothing materials: natural — wool, or synthetic — acrylic is better. Each of them exerts a different effect on the human organism. The usefulness of a given type of clothing material seems to depend on the human physiological state and the related thermoregulatory processes

Minimal hepatic encephalopathy: Effect of H. pylori infection and small intestinal bacterial overgrowth treatment on clinical outcomes

The effect Helicobacter pylori (Hp) infection and small intestinal bacterial over growth (SIBO) in minimal hepatic encephalopathy (MHE) is not well understood. The aim of the study was to determine the effect of eradication of Hp infection and SIBO treatment on MHE in patients with cirrhosis. Patients with cirrhosis were enrolled and MHE was determined by psychometric tests and critical flicker frequency analysis. Hp infection and SIBO were assessed by urea breath and Hydrogen breath tests respectively in patients with cirrhosis and in healthy volunteers. Patients with Hp infection and SIBO were given appropriate treatment. At six weeks follow-up, presence of Hp infection, SIBO and MHE status was reassessed. Ninety patients with cirrhosis and equal number of healthy controls were included. 55 (61.1%) patients in the cirrhotic group were diagnosed to have underlying MHE. Among cirrhotic group, Hp infection was present in 28 with MHE (50.9%) vs. in 15 without MHE (42.8%) (p = 0.45). Similarly, SIBO was present in 17 (30.9%) vs. 11 (31.4%) (p = 0.95) in patients with and without MHE respectively. In comparison with healthy controls, patients with cirrhosis were more frequently harboring Hp and SIBO (47.7% vs. 17.7% (p \u3c 0.001) and 31.1% vs. 4.4% (p \u3c 0.001) respectively. On follow-up, all patients showed evidence of eradication of Hp and SIBO infection. Treatment of SIBO significantly improved the state of MHE in cirrhotics, however eradication of Hp infection did not improve MHE significantly. Additionally, patients with low Model for End-Stage Liver Disease (MELD) score and belonging to Child class B had significantly better improvement in MHE. A large number of patients with cirrhosis had either active Hp infection or SIBO with or without MHE, compared to healthy controls. Treatment of SIBO significantly improved MHE in patients with cirrhosis, whereas eradication of Hp did not affect the outcome of MHE in these patients

The Effect of Branched Chain Amino Acids and L-Ornithine L-Aspartate Combination as the Late Evening Snacks on Nutritional Status and Minimal Hepatic Encephalopathy in Liver Cirrhosis

Background:Minimal hepatic encephalopathy (MHE) in liver cirrhotic patients is critical manifestation of low grade hepatic encephalopaty (HE), is caused quality of life decrease and risk of deteriorating into distinct HE. The study was conducted to asses the effect of combination of branched-chain amino acids (BCAA) and L-ornithine L-aspartate (LOLA), which was given late evening, on nutritional status and degree of HE.Method: This single-blind randomized study was conducted on liver cirrhotic outpatients in hepatology clinic of Cipto Mangunkusumo Hospital period June 2011-June 2012. The study subjects were divided into two groups, group of late evening snack (LS) and day snack (DS). Each group was supplemented with combination of milk of BCAAs and LOLA (3.7 g/serving). Evaluation based on history, physical examination, laboratory tests and critical flicker frequency (CFF) was performed one month after the intervention. Data were statistically analyzed with SPSS 15.Results: Thirty-two patients whose the inclusion criteria were divided into 16 subjects for each group, LS and DS. After one month of the intervention, the average level of prealbumin for DS group was increased statistically significant (p < 0.001), but not significant for LS group (p = 0.259). The increase of average body weight,mid-arm muscle circumference (MAMC) and CFF test result in both groups. There was no improvement on subject global assessment (SGA) score after one month intervention in both groups.Conclusion: This study proved that giving combination of BCAAs and LOLA may improve the condition of MHE, however for nutritional status can not be assessed

Temporal visual resolution and disease severity in MS

OBJECTIVE: To examine temporal visual resolution assessed as critical flicker frequency (CFF) in patients with MS and to investigate associations with visual system damage and general disability and cognitive function. METHODS: Thirty-nine patients with MS and 31 healthy controls (HCs) were enrolled in this cross-sectional study and underwent CFF testing, high- and low-contrast visual acuity, alertness and information processing speed using the paced auditory serial addition task (PASAT), and retinal optical coherence tomography (OCT). In patients with MS, visual evoked potentials (VEPs) and Expanded Disability Status Scale (EDSS) scores were assessed. RESULTS: CFF in patients with MS (mean ± SD: 40.9 ± 4.4 Hz) was lower than in HCs (44.8 ± 4.4 Hz, p < 0.001). There was no significant CFF difference between eyes with and without previous optic neuritis (ON). CFF was not associated with visual acuity, VEP latency, the peripapillary retinal nerve fiber layer thickness, and the combined ganglion cell and inner plexiform layer volume. Instead, reduced CFF was associated with worse EDSS scores (r(2) = 0.26, p < 0.001) and alertness (r(2) = 0.42, p = 0.00042) but not with PASAT (p = 0.33). CONCLUSION: CFF reduction in MS occurs independently of ON and structural visual system damage. Its association with the EDSS score and alertness suggests that CFF reflects global disease processes and higher cortical processing rather than focal optic nerve or retinal damage

A reinterpretation of critical flicker-frequency (CFF) data reveals key details about light adaptation and normal and abnormal visual processing

Our ability to see flicker has an upper frequency limit above which flicker is invisible, known as the “critical flicker frequency” (CFF), that typically grows with light intensity (I). The relation between CFF and I, the focus of nearly 200 years of research, is roughly logarithmic, i.e., CFF ∝ log(I)—a relation called the Ferry-Porter law. However, why this law should occur, and how it relates to the underlying physiology, have never been adequately explained. Over the past two decades we have measured CFF in normal observers and in patients with retinal gene defects. Here, we reanalyse and model our data and historical CFF data. Remarkably, CFF-versus-I functions measured under a wide range of conditions in patients and in normal observers all have broadly similar shapes when plotted in double-logarithmic coordinates, i.e., log (CFF)-versus-log(I). Thus, the entire dataset can be characterised by horizontal and vertical logarithmic shifts of a fixed-shape template. Shape invariance can be predicted by a simple model of visual processing built from a sequence of low-pass filters, subtractive feedforward stages and gain adjustment (Rider, Henning & Stockman, 2019). It depends primarily on the numbers of visual processing stages that approach their power-law region at a given intensity and a frequency-independent gain reduction at higher light levels. Counter-intuitively, the CFF-versus-I relation depends primarily on the gain of the visual response rather than its speed—a conclusion that changes our understanding and interpretation of human flicker perception. The Ferry-Porter “law” is merely an approximation of the shape-invariant template

The Efficacy of L-Ornithine L-Aspartate Granules and Normal Protein Diet in Minimal Hepatic Encephalopathy with Malnutrition

Background: The dietary protein restriction that was commonly recommended to hepatic encephalopathy (HE) patients, often leads to malnutrition, whereas malnutrition can deteriorate cirrhosis prognosis. The aims of this study were to find out encephalopathy improvement that was measured by critical flicker frequency (CFF) test and nutritional status by measuring prealbumin level after L-Ornithine L-Aspartate (LOLA) treatment with adequate calories and protein intake in patients with HE. Method: Patients with liver cirrosis who visited Cipto Mangunkusumo hospital on June-October 2009 was evaluated by CFF test using HEPAtonormTM device. Encephalopathy was defined when CFF &lt; 39 Hz. Nutritional status was measured by the mid-arm muscle circumference (MAMC) and was stated as malnutrition when the MAMC was below the 15th percentile. Patients had been treated by 3 x 6 mg LOLA granules for 2 weeks, and adequate calories and protein intake with branched-chain amino acid (BCAAs) substitution. The change of encephalopaty was evaluated by the CFF test and the nutritional status by measuring prealbumin blood level. Results: There were 17 patients with liver cirrhosis who fulfilled the inclusion criteria. The mean CFF Result increased from 34.1 ± 2.5 Hz to 36.5 ± 2.9 Hz after LOLA treatment with the adequate calories and protein intake including BCAAs substitution, which was statistically significant (p &lt; 0.001) compared to before treatment. The prealbumin level also increased significantly compared before treatment, i.e. from 5.4 ± 2.1 mg/dL to 6.4 ± 2.6 mg/dL, p = 0.008. Conclusion: HE patients with malnutrition could be given adequate calorie and protein with BCAAs substitution to improve their nutritional status, and LOLA granules for the improvement of HE

Predicting visible flicker in temporally changing images

Novel display algorithms such as low-persistence displays, black frame insertion, and temporal resolution multiplexing in- troduce temporal change into images at 40-180 Hz, on the bound- ary of the temporal integration of the visual system. This can lead to flicker, a highly-objectionable artifact known to induce viewer discomfort. The critical flicker frequency (CFF) alone does not model this phenomenon well, as flicker sensitivity varies with contrast, and spatial frequency; a content-aware model is re- quired. In this paper, we introduce a visual model for predicting flicker visibility in temporally changing images. The model per- forms a multi-scale analysis on the difference between consecu- tive frames, normalizing values with the spatio-temporal contrast sensitivity function as approximated by the pyramid of visibility. The output of the model is a 2D detection probability map. We ran a subjective flicker marking experiment to fit the model pa- rameters, then analyze the difference between two display algo- rithms, black frame insertion and temporal resolution multiplex- ing, to demonstrate the application of our model

A complex physiology-based empirical usability evaluation method in practice

This paper outlines the INTERFACE usability evaluation methodology developed by researchers of our department. It is based on the simultaneous assessment of Heart Period Variability (HPV), Skin Conductance (SC), and other data. One of the highlights of this methodology is its capability to identify quality attributes of software elements with a time-resolution of only a few seconds: in particular cases it can assess 2- or 3-second events. The Department of Ergonomics and Psychology at the Budapest University of Technology and Economics carried out applied research projects assessing very various software. After these, we can show different types of typical software problems identified by our method. The method of analysis allows us not only to decide what types of problems are significant to the users; however, on the other hand, the method allows us to decide, to what extent the found problems and their assessed severity concern all the users in general, or how these things depend on the type and characteris tics of the users