Interpolation Processes in the Perception of Real and Illusory Contours

Perception ◽  
1997 ◽  
Vol 26 (11) ◽  
pp. 1445-1458 ◽  
Author(s):  
Karl R Gegenfurtner ◽  
Joel E Brown ◽  
Jochem Rieger
Keyword(s):  
Line Segment ◽  
Spatial Configuration ◽  
Relative Length ◽  
Interpolation Process ◽  
Illusory Contours ◽  
Low Contrast ◽  
Line Segments ◽  
Significant Difference ◽  
Presentation Time ◽  
The Right

The spatial and temporal characteristics of mechanisms that bridge gaps between line segments were determined. The presentation time that was necessary for localisation and identification of a triangular shape made up of pacmen, pacmen with lines, lines, line segments (corners), or pacmen with circles (amodal completion) was measured. The triangle was embedded in a field of distractors made up of the same components but at random orientations. Subjects had to indicate whether the triangle was on the left or on the right of the display (localisation) and whether it was pointing upward or downward (identification). Poststimulus masks consisted of pinwheels for the pacmen stimuli or wheels defined by lines. Stimuli were presented on a grey background and defined by luminance or isoluminant contrast. Thresholds were fastest when the triangle was defined by real contours, as for the pacmen with lines (105 ms) and the lines only (92 ms), slightly slower for corners (118 ms) and pacmen (136 ms), and much slower for the amodally completed pacmen (285 ms). For all inducer types localisation was about 20 ms faster than identification. In a second experiment the relative length of the gap between inducers was varied. Thresholds increased as a function of gap length, indicating that the gaps between the inducers need to be interpolated. There was no significant difference in the speed of this interpolation process between the pacman stimuli and the line-segment stimuli. About 40 ms were required to interpolate 1 deg of visual angle, corresponding to about one third of the distance between inducers. In a third experiment, it was found that processing of isoluminant stimuli was as fast as for low-contrast luminance stimuli, when targets were defined by real contours (lines), but much slower for illusory contours (pacmen). The conclusion is that the time necessary to interpolate a contour depends greatly on the spatial configuration of the stimulus. Since interpolation is faster for the line-segment stimuli, which do not elicit the percept of an illusory contour, the interpolation process seems to be independent of the formation of illusory contours.

Agreement analysis comparing iPad LCVA and Sloan testing in multiple sclerosis patients

2017 ◽  
Vol 24 (8) ◽  
pp. 1126-1130 ◽  
Author(s):  
Neda Sattarnezhad ◽  
Samantha Farrow ◽  
Dorlan Kimbrough ◽  
Bonnie Glanz ◽  
Brian Healy ◽  
...  
Keyword(s):  
Multiple Sclerosis ◽  
Visual Acuity ◽  
T Test ◽  
Computerized Testing ◽  
Low Contrast ◽  
Significant Difference ◽  
Increased Sensitivity ◽  
The Right ◽  
Multiple Sclerosis Patients ◽  
Paired T Test

Background: Visual symptoms are common in multiple sclerosis (MS). Low-contrast visual acuity (LCVA) testing using Sloan charts has demonstrated increased sensitivity for visual deficits compared to high-contrast acuity testing. Computerized testing of visual acuity may facilitate use in the clinic setting. Objectives: To evaluate the agreement between an iPad-based and Sloan testing of LCVA in a cohort of MS patients. Methods: A total of 38 patients with relapsing-remitting MS were enrolled after providing informed written consent at Partners MS Center, Brigham and Women’s hospital. Monocular LCVA was measured using retroilluminated Sloan chart and iPad-based LogMAR chart. Number of correct letters and agreement between two measurements were assessed for each eye using Bland–Altman analysis and paired t-test. Results: For both eyes, there was no significant difference in number correct between the two measurements using a paired t-test, and there was high correlation between two measurements (oculus dextrus (OD) r = 0.89, p < 0.001; oculus sinister (OS) r = 0.78, p < 0.001). The limits of agreement were −7.9 to +8.5 letters for the right eye and −10.9 to +11.2 letters for the left eye. Conclusion: An iPad-based LCVA test shows good agreement with Sloan testing in MS patients.

scholarly journals Relative length of human kidney as more precise measuring of normal kidney

2010 ◽  
Vol 63 (11-12) ◽  
pp. 784-787 ◽  
Author(s):  
Slobodan Vlajkovic ◽  
Rade Cukuranovic ◽  
Marija Dakovic-Bjelakovic ◽  
Goran Ilic ◽  
Tijana Jaksic ◽  
...  
Keyword(s):  
Kidney Development ◽  
Left Kidney ◽  
Body Height ◽  
Relative Length ◽  
The Body ◽  
Kidney Length ◽  
Significant Difference ◽  
The Absolute ◽  
The Right ◽  
Renal Length

Introduction. Malformations in kidney development and kidney diseases are accompanied with changes in their size. For kidney evaluation in clinical practice, the kidney length is the most widely used measurement, since it provides the most precise results and it is easy to perform. Recently, the measurement of relative renal length has become more preferable as it takes into account the body height. The aim of this study was to measure both the absolute and relative length of normal cadaveric kidneys according to the body height, sex and age. Material and methods. In this study, we examined 95 adult cadaveric kidneys, without renal and vascular impairment, their age ranging from 23-87 years. To determine the period of the most abundant changes in kidney length, we separated them into a 10-year range. The relative renal length was calculated using the kidney length anybody height ratio (kidney/body ratio). Results. The absolute and relative length of left kidney in males was longer than the right one, with a statistically significant correlation. In females, the left kidney length was also longer than the right one, however, without a statistical significance. In contrast to the absolute length, the relative length of both kidneys did not show a significant difference between sexes, and did not manifest a significant decrease with age. There was a significant correlation between the kidney length and the subject?s height. Conclusion. The relative renal length represents kidney size better than the absolute renal length because it eliminates sex and height differences until the age of 59 year. From the seventh decade of life, there is a significant decrease in both the absolute and relative renal length.

Suicidal Ideation and Self-Determination in Institutionalized Elderly

Crisis ◽  
2001 ◽  
Vol 22 (1) ◽  
pp. 15-19 ◽  
Author(s):  
Andrée Fortin ◽  
Sylvie Lapierre ◽  
Jacques Baillargeon ◽  
Réal Labelle ◽  
Micheline Dubé ◽  
...  
Keyword(s):  
Self Determination ◽  
Current Debate ◽  
Elderly Persons ◽  
Rational Suicide ◽  
Institutionalized Elderly ◽  
Significant Difference ◽  
Social Subscale ◽  
Civil Status ◽  
The Right ◽  
Taking Action

The right to self-determination is central to the current debate on rational suicide in old age. The goal of this exploratory study was to assess the presence of self-determination in suicidal institutionalized elderly persons. Eleven elderly persons with serious suicidal ideations were matched according to age, sex, and civil status with 11 nonsuicidal persons. The results indicated that suicidal persons did not differ from nonsuicidal persons in level of self-determination. There was, however, a significant difference between groups on the social subscale. Suicidal elderly persons did not seem to take others into account when making a decision or taking action. The results are discussed from a suicide-prevention perspective.

Less is more: Simple stimuli provoke more variable search strategies.

2020 ◽  
Author(s):  
Anna Nowakowska ◽  
Alasdair D F Clarke ◽  
Jessica Christie ◽  
Josephine Reuther ◽  
Amelia R. Hunt
Keyword(s):  
Line Segment ◽  
Search Strategies ◽  
Complex Objects ◽  
Search Behaviour ◽  
Line Segments ◽  
Surface Level ◽  
Efficient Search ◽  
Less Is More ◽  
Dramatic Shift

We measured the efficiency of 30 participants as they searched through simple line segment stimuli and through a set of complex icons. We observed a dramatic shift from highly variable, and mostly inefficient, strategies with the line segments, to uniformly efficient search behaviour with the icons. These results demonstrate that changing what may initially appear to be irrelevant, surface-level details of the task can lead to large changes in measured behaviour, and that visual primitives are not always representative of more complex objects.

Pediatric Cataract Surgery: Comparison between Ages at Surgery and Contrast Sensitivity Outcomes

2019 ◽  
Vol 43 (1) ◽  
pp. 50
Author(s):  
Aquirina Caesari Putri ◽  
Rozalina Loebis
Keyword(s):  
Visual Acuity ◽  
Cataract Surgery ◽  
Contrast Sensitivity ◽  
Cataract Extraction ◽  
Significant Negative Correlation ◽  
Natural World ◽  
P Value ◽  
Pediatric Cataract ◽  
Low Contrast ◽  
Significant Difference

Background: Pediatric cataracts are major causes of children’s blindness. Surgery has proven to be beneficial in terms of visual function prognosis. Contrast sensitivity evaluation after surgery is as important as visual acuity considering that natural world consists of various objects in low-to-medium contrasts. The purpose of this study is to analyze the difference of contrast sensitivity outcomes based on ages at surgery. Method: Retrospective data of children with pediatric developmental cataract from July 2013 to November 2015 were collected. All children who underwent cataract surgery at 60-months-old or less were randomized into two groups, ≤24 months and >24-to-60 months. Contrast sensitivity was then examined with preferential-looking method using Hiding Heidi low-contrast test face chart. The main outcome measures were contrast sensitivity of both groups. Age-at-evaluation, cataract onset, duration of follow-up, duration of deprivation and visual acuity were also noted. Result: Of 14 children (23 eyes), 11 eyes (47,8%) were in ≤24 months group, 12eyes (52,2%) were in >24-to-60 months group. All eyes underwent cataract extraction and similar type of intraocular lens implantation. Mean age-at-surgery was 28,2 months±16,8 (SD). Mean contrast sensitivity for each group was 47,50 %±42,29 and 18,33%±27,38, respectively, with p-value 0,031. Further analysis of Spearman’s correlation test demonstrated significant negative correlation (rs = -0,559; p = 0,006) between the two groups. Conclusion: There was statistically significant difference in contrast sensitivity between those who underwent surgery at ≤24 months and >24-to-60 months. Children who underwent surgery at older ages tend to have better contrast sensitivity afterwards.

DeVega versus ring annuloplasty in severe functional tricuspid insufficiency and their impact on the right ventricle

2019 ◽  
Vol 1 (4) ◽  
pp. 133-139
Author(s):  
Yasser Hamdy ◽  
Mohammed Mahmoud Mostafa ◽  
Ahmed Elminshawy
Keyword(s):  
Right Ventricular ◽  
Tricuspid Valve ◽  
Tricuspid Regurgitation ◽  
Early Postoperative Period ◽  
Tricuspid Valve Repair ◽  
Ring Annuloplasty ◽  
Significant Difference ◽  
Group A ◽  
Group B ◽  
The Right

Background: Functional tricuspid valve regurgitation secondary to left-sided valve disease is common. DeVega repair is simple, but residual regurgitation with subsequent impairment of the right ventricular function is a concern. This study aims to compare tricuspid valve repair using DeVega vs. ring annuloplasty and their impact on the right ventricle in the early postoperative period and after six months. Methods: This is a prospective cohort study of 51 patients with rheumatic heart disease who underwent tricuspid valve repair for secondary severe tricuspid regurgitation. Patients were divided into two groups: group A; DeVega repair (n=34) and group B; ring annuloplasty repair (n=17). Patients were assessed clinically and by echocardiography before discharge and after six months for the degree of tricuspid regurgitation, right ventricular diameter and tricuspid annular plane systolic excursion (TAPSE). Results: Preoperative echocardiographic assessment showed no difference in left ventricular end-systolic diameter, end-diastolic diameter, ejection fraction and right ventricular diameter, however; group A had significantly better preoperative right ventricular function measured by TAPSE (1.96 ± 0.27 vs1.75 ± 0.31 cm; p=0.02). Group B had significantly longer cardiopulmonary bypass time (127.65 ± 13.56 vs. 111.74 ± 18.74 minutes; p= 0.003) and ischemic time (99.06 ± 11.80 vs. 87.15 ± 16.01 minutes; p= 0.009). Pre-discharge, there was no statistically significant difference in the degree of tricuspid regurgitation, but the right ventricular diameter was significantly lower in group B (2.66 ± 0.41 and 2.40 ± 0.48 cm; p=0.049). After six months of follow up, the degree of tricuspid regurgitation (p= 0.029) and the right ventricular diameter were significantly lower in the ring annuloplasty group (2.56 ± 0.39 and 2.29 ± 0.44 cm; p=0.029). Although there was a statistically significant difference in preoperative TAPSE, this difference disappeared after six months. Conclusion: Both DeVega and ring annuloplasty techniques were effective in the early postoperative period, ring annuloplasty was associated with lesser residual regurgitation and better right ventricular remodeling in severe functional tricuspid regurgitation than DeVega procedure after 6-months of follow up.

scholarly journals POS0586 RHEUMATOID ARTHRITIS IS AN INFLAMMATORY DISEASE WITH A HIGH CARDIOVASCULAR RISK

2021 ◽  
Vol 80 (Suppl 1) ◽  
pp. 526.1-526
Author(s):  
L. Nacef ◽  
H. Riahi ◽  
Y. Mabrouk ◽  
H. Ferjani ◽  
K. Maatallah ◽  
...  
Keyword(s):  
Rheumatoid Arthritis ◽  
Risk Factors ◽  
Cardiovascular Risk ◽  
Carotid Artery ◽  
Internal Carotid ◽  
Subclinical Atherosclerosis ◽  
External Carotid ◽  
Significant Difference ◽  
The Mean ◽  
The Right

Background:Hypertension, diabetes, and dyslipidemia are traditional risk factors of cardiac events. Carotid ultrasonography is an available way to detect subclinical atherosclerosis.Objectives:This study aimed to compare the intima-media thickness in RA patients based on their personal cardiovascular (CV) history of hypertension (hypertension), diabetes, and dyslipidemia.Methods:The present study is a prospective study conducted on Tunisian RA patients in the rheumatology department of Mohamed Kassab University Hospital (March and December 2020). The characteristics of the patients and those of the disease were collected.The high-resolution B-mode carotid US measured the IMT, according to American Society of Echocardiography guidelines. The carotid bulb below its bifurcation and the internal and external carotid arteries were evaluated bilaterally with grayscale, spectral, and color Doppler ultrasonography using proprietary software for carotid artery measurements. IMT was measured using the two inner layers of the common carotid artery, and an increased IMT was defined as ≥0.9 mm. A Framingham score was calculated to predict the cardiovascular risk at 10-year.Results:Forty-seven patients were collected, 78.7% of whom were women. The mean age was 52.5 ±11.06 [32-76]. The rheumatoid factor (RF) was positive in 57.8% of cases, and anti-citrullinated peptide antibodies (ACPA) were positive in 62.2% of cases. RA was erosive in 81.6% of cases. Hypertension (hypertension) was present in 14.9% of patients, diabetes in 12.8% of patients, and dyslipidemia in 12.8% of patients. Nine patients were active smokers. The mean IMT in the left common carotid (LCC) was 0.069 ±0.015, in the left internal carotid (LIC) was 0.069 ±0.015, in the left external carotid (LEC) was 0.060 ±0.023. The mean IMT was 0.068 ±0.01 in the right common carotid (RCC), 0.062 ±0.02 in the right internal carotid (RIC), and 0.060 ±0.016 in the right external carotid (REC). The IMT was significantly higher in the left common carotid (LCC) in patients with hypertension (p=0.025). There was no significant difference in the other ultrasound sites (LIC, LEC, RCC, RIC, and REC) according to the presence or absence of hypertension. The IMT was also significantly increased in patients with diabetes at LCC (p=0.017) and RIC (p=0.025). There was no significant difference in the IMT at different ultrasound sites between patients with and without dyslipidemia.Conclusion:Hypertension was significantly associated with the increase in IMT at the LCC level in RA patients. Diabetes had an impact on IMT in LCC and RIC. However, dyslipidemia did not affect the IMT at the different ultrasound sites.References:[1]S. Gunter and al. Arterial wave reflection and subclinical atherosclerosis in rheumatoid arthritis. Clinical and Experimental Rheumatology 2018; 36: Clinical E.xperimental.[2]Aslan and al. Assessment of local carotid stiffness in seronegative and seropositive rheumatoid arthritis. SCANDINAVIAN CARDIOVASCULAR JOURNAL, 2017.[3]Martin I. Wah-Suarez and al, Carotid ultrasound findings in rheumatoid arthritis and control subjects: A case-control study. Int J Rheum Dis. 2018;1–7.[4]Gobbic C and al. Marcadores subclínicos de aterosclerosis y factores de riesgo cardiovascular en artritis temprana. Subclinical markers of atherosclerosis and cardiovascular risk factors in early arthritis marcadores subclínicos de aterosclerose e fatores de risco cardiovascular na artrite precoce.Disclosure of Interests:None declared

The Effect of Reflexology on Lactation in Women Who Had Cesarean Section: A Randomized Controlled Pilot Study

2021 ◽  
pp. 1-8
Author(s):  
Sevde Aksu ◽  
Pelin Palas Karaca
Keyword(s):  
Pilot Study ◽  
Cesarean Section ◽  
Intervention Group ◽  
Control Group ◽  
Breast Pain ◽  
Randomized Controlled ◽  
Significant Difference ◽  
The Right ◽  
Documentation Tool ◽  
And Control

<b><i>Aim:</i></b> The research was conducted as a randomized controlled pilot study to evaluate the effects of reflexology on lactation in mothers who delivered by cesarean section (CS). <b><i>Methods:</i></b> A single-blind randomized controlled experimental study was conducted with a total of 60 postpartum women in the reflexology application (<i>n</i> = 30) and control groups (<i>n</i> = 30). After the CS, the mothers in the control group were given approximately 3-h routine nursing care after recovering from the effects of anesthesia; the introductory information form was applied, and the Breastfeeding Charting System and Documentation Tool (LATCH) and visual analog scale (VAS) for the signs of the onset of lactation were implemented on the first and second days. Reflexology was applied to the women in the intervention group after an average of 3 h following the mother’s condition had become stable and she had recovered from the effects of anesthesia. Reflexology was applied a total of 20 min – 10 min for the right foot, 10 min for the left foot – twice a day with 8-h intervals on the first and second days after CS. After the last reflexology application, the LATCH and VAS for the signs of the onset of lactation were applied. <b><i>Results:</i></b> Of the women, 70% breastfed their babies within 60 min after delivery; 46.7% of the mothers received breastfeeding training and 81.7% needed support for breastfeeding after the CS. The LATCH breastfeeding scores of the women in the intervention group on both days were significantly higher compared to those of the women in the control group (<i>p</i> &#x3c; 0.001). On the first day after the CS, apart from breast pain, there was no significant difference between the two groups in terms of breast heat and breast tension (<i>p</i> &#x3e; 0.05). On the second day after the CS, apart from breast tension, there was no significant difference between the groups in terms of breast heat and breast pain (<i>p</i> &#x3c; 0.05). In the study, women in the intervention group were found to have higher scores in terms of all three symptoms compared to the control group (<i>p</i> &#x3c; 0.05). <b><i>Conclusions:</i></b> In the study, it was determined that LATCH scores and signs of the onset of breastfeeding increased in the mothers who received reflexology after CS.

scholarly journals Frequency-Following Response (FFR) in Military Pilots

2020 ◽  
Author(s):  
Graziela Maria Martins-Moreira ◽  
Alessandra Spada Durante
Keyword(s):  
Pure Tone Audiometry ◽  
Control Group ◽  
Study Group ◽  
Aircraft Accidents ◽  
Frequency Following Response ◽  
Significant Difference ◽  
Qualitative Variables ◽  
Chi Squared ◽  
The Right ◽  
Military Pilots

Abstract Introduction Good hearing in pilots, including central auditory skills, is critical for flight safety and the prevention of aircraft accidents. Pure tone audiometry alone may not be enough to assess hearing in the members of this population who, in addition to high noise levels, routinely face speech recognition tasks in non-ideal conditions. Objective To characterize the frequency-following response (FFR) of a group of military pilots compared with a control group. Methods Twenty military pilots in the Study Group and 20 non-pilot military personnel, not exposed to noise in their work, in the Control Group, all with normal hearing, aged between 30 and 40 years old, completed a questionnaire to assess their hearing habits, and their FFRs were measured with a /da/ syllable (duration 40 milliseconds, speed 10.9/s), at 80 dB NA in the right ear. All procedures were approved by the ethical committee of the institution. Statistical analysis was performed using the t-Student or Mann-Whitney tests for quantitative variables, and the Fisher or chi-squared tests for qualitative variables, and a value of p < 0.05 was considered to be statistically significant. Results There was no significant difference between the groups regarding auditory habits. In the FFR, wave amplitudes A (p = 0.01) and C (p = 0.04) were significantly lower in the Study Group. Conclusion Working as a military pilot can be a crucial factor in determining an individual's typical FFR pattern, demonstrated in the present study by statistically significant reductions in the amplitudes of the A and C waves.

scholarly journals In vivo exploration of synaptic projections in frontotemporal dementia

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Eric Salmon ◽  
Mohamed Ali Bahri ◽  
Alain Plenevaux ◽  
Guillaume Becker ◽  
Alain Seret ◽  
...  
Keyword(s):  
Frontotemporal Dementia ◽  
Input Function ◽  
Parahippocampal Gyrus ◽  
Exploratory Research ◽  
Social Brain ◽  
Synaptic Density ◽  
Clinical Disorder ◽  
Significant Difference ◽  
The Right

AbstractThe purpose of this exploratory research is to provide data on synaptopathy in the behavioral variant of frontotemporal dementia (bvFTD). Twelve patients with probable bvFTD were compared to 12 control participants and 12 patients with Alzheimer’s disease (AD). Loss of synaptic projections was assessed with [18F]UCBH-PET. Total distribution volume was obtained with Logan method using carotid artery derived input function. Neuroimages were analyzed with SPM12. Verbal fluency, episodic memory and awareness of cognitive impairment were equally impaired in patients groups. Compared to controls, [18F]UCBH uptake tended to decrease in the right anterior parahippocampal gyrus of bvFTD patients. Loss of synaptic projections was observed in the right hippocampus of AD participants, but there was no significant difference in [18F]UCBH brain uptake between patients groups. Anosognosia for clinical disorder was correlated with synaptic density in the caudate nucleus and the anteromedial prefrontal cortex. This study suggests that synaptopathy in bvFTD targets the temporal social brain and self-referential processes.

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