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Results for “depth adaptation”

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PubMed1995

[Effect of light intensity on binocular distance perception].

Empirical investigations of perceived binocular distance often use an experimental setting in which real point-like light sources are presented in a completely dark surround. The results obtained, however, may be a consequence of the joint influence of binocular and monocular depth cues. Here, for the first time, the effect of (monocular) illumination cues on the locus of perceived equidistance is experimentally investigated by manipulating the luminous intensity of the stimuli. In a computer-controlled setup, small light-emitting diodes were presented in complete darkness. Five subjects judged the perceived distance of stimuli, which appeared in four directions and at five levels of luminous intensity, with respect to a fixed standard. Adaptive methods were used to determine perceived equidistance. Although the results show a significant effect of illumination cues, their influence on the locus of perceived equidistance turned out to be far less than previously supposed. For three subjects it was practically negligible.

Adult↗

PubMed1995

[Diagnosis of changes in the knee joint of high performance athletes].

Sport-associated knee-joint alterations are frequent. A correct and rapid differentiation between traumatic lesions, chronic degenerative changes, and adaptive processes is important with regard to therapy as well as training and competitive planning for athletes. After the case history and physical examination, X-ray images are an absolute necessity for more in-depth diagnostic procedures. Depending on the clinical symptoms, partial aspects of the knee-joint can be visualized by sonography as well as by conventional tomography and computed tomography. If, however, a comprehensive evaluation of all knee-joint structures is needed, magnetic resonance imaging of the knee-joint should be performed. As a rapid, noninvasive procedure with high diagnostic reliability for all essential knee-joint structures only magnetic resonance imaging presently fulfills the specific demands placed on a modern diagnostic procedure by doctors working in sports-medicine.

Athletic Injuries↗

PubMed1994

Low vision: how to assess and treat its emotional impact.

For many older adults facing visual loss, the frustration and distress that makes life's activities difficult or impossible may lead to clinically significant emotional problems. Patients may feel a loss of independence and control, poor self-esteem, and strained social relationships. Clinically, the most common emotional problems related to vision loss are adjustment disorder and major depressive episode. For patients with adjustment disorder, counseling or psychotherapy is recommended for both the patient and family members. Patients with major depression must be evaluated and referred for more in-depth psychiatric evaluation and treatment. Resolution of these disorders is important before a patient can pursue adequate rehabilitation.

Adaptation, Psychological↗

PubMed1976

Correcting high anisometropia: two case reports.

In the cases reported, the anisometropia had not been corrected previously. Despite the common belief that such a correction would induce intolerable symptoms in adults, both patients successfully adapted to the full correction within a few days, showing marked improvement in binocular vision skills.

Adult↗

PubMed2004

Sensitivity to depth relief on slanted surfaces.

The finest stereoacuity is known to depend on the disparity of a target relative to other visible points. Here we show that a more important factor in determining sensitivity to displacement can be the disparity of a target relative to an invisible interpolation plane through other neighboring points. We tested the sensitivity of observers to displacements of the central column of a regular grid of dots that was either fronto-parallel or slanted about a vertical axis. We found that subjects' sensitivity to displacement was better predicted by a model based on the disparity of a target with respect to the grid plane than it was by a model based on disparity with respect to other reference points. In control conditions carried out on one subject, we found that this result did not depend on adaptation to the grid slant because it also occurred when the direction of grid slant varied from trial to trial. Nor did it depend on the perception of slant, because the data were similar for trials on which the grid was perceived as approximately fronto-parallel or markedly slanted. Our results indicate that sensitivity to the depth component of the target displacement is based on disparity relative to a local reference plane.

Cues↗

PubMed2000

Does pretreatment of cavities effectively promote good marginal adaptation of glass-ionomer cements?

PURPOSE: The aim of this laboratory study was to evaluate the marginal sealing ability of four glass-ionomer cements in cervical restorations (Class V) using dye penetration. Two conventional (C-GIC) and two resin-modified (RM-GIC) cements were used either with or without dentin conditioning with polyacrylic acid. MATERIALS AND METHODS: 96 cervical cavities of standardized size were prepared in vitro in the vestibular and lingual portions at the cementoenamel level of 48 premolars. The coronal margins were prepared in enamel, the apical margins were localized in dentin. The 96 cavities were randomly divided into 4 groups of n = 24 each. The cavities of each group were filled with one of the test materials, and only half of the cavities received a dentin conditioning for 20 s with polyacrylic acids before filling. The fillings were finished with a set of abrasive disks 24 h after setting. The restored teeth were stored in saline for 4 weeks and subjected to dye penetration. The depth of dye penetration along the coronal and apical margin was measured on 4 longitudinal sections of each tooth with a semi-automatic image analysis system at 40x magnification. RESULTS: Mean depth of dye penetration ranged from 0 (ChemFil superior without conditioner) to 0.13 mm (ChemFil superior with conditioner) at enamel sites, and from 0.02 (Fuji II LC with conditioner) to 0.74 mm (ChemFil superior with and without conditioner) at dentin sites. CONCLUSION: The conditioning of the cavities before filling improved the marginal adaptation significantly only in the Ketac-Fil group. Conventional glass-ionomer cements (C-GIC) in general demonstrated a lower sealing ability than the light-activated, resin-modified cements (RM-GIC). The adaptation of Photac-Fil quick is best without pretreatment--as recommended by the manufacturer.

Acid Etching, Dental↗

PubMed2004

Stereoscopic processing of absolute and relative disparity in human visual cortex.

Stereoscopic vision relies mainly on relative depth differences between objects rather than on their absolute distance in depth from where the eyes fixate. However, relative disparities are computed from absolute disparities, and it is not known where these two stages are represented in the human brain. Using functional MRI (fMRI), we assessed absolute and relative disparity selectivity with stereoscopic stimuli consisting of pairs of transparent planes in depth in which the absolute and relative disparity signals could be independently manipulated (at a local spatial scale). In experiment 1, relative disparity was kept constant, while absolute disparity was varied in one-half the blocks of trials ("mixed" blocks) and kept constant in the remaining one-half ("same" blocks), alternating between blocks. Because neuronal responses undergo adaptation and reduce their firing rate following repeated presentation of an effective stimulus, the fMRI signal reflecting activity of units selective for absolute disparity is expected to be smaller during "same" blocks as compared with "mixed" ones. Experiment 2 similarly manipulated relative disparity rather than absolute disparity. The results from both experiments were consistent with adaptation with differential effects across visual areas such that 1) dorsal areas (V3A, MT+/V5, V7) showed more adaptation to absolute than to relative disparity; 2) ventral areas (hV4, V8/V4alpha) showed an equal adaptation to both; and 3) early visual areas (V1, V2, V3) showed a small effect in both experiments. These results indicate that processing in dorsal areas may rely mostly on information about absolute disparities, while ventral areas split neural resources between the two types of stereoscopic information so as to maintain an important representation of relative disparity.

Depth Perception↗

PubMed1984

Stereological studies on the rat small intestinal epithelium. III. Effects of short-term alloxan diabetes.

Short-term experimental diabetes was used to explore the effect of hyperplastic adaption of the small intestine mucosa on the structure of its absorptive cells. Diabetes was induced in adult female rats by intravenous alloxan administration under kidney protection; similar rats, injected with physiological saline, served as controls. Quantitative light microscopy, performed after 1 month of diabetes, revealed structural changes in the jejunal mucosa consistent with hyperplasia. These changes comprised increased height of the villi (31%) and increased depth of the crypts (34%) in comparison with the control rats. At the electron microscopical level, stereological measurements of the jejunal absorptive cells revealed a decrease in their apical surface area, both for the apical surface density (24%) and for the enlargement factor due to the microvilli (12%). In the duodenal mucosa, this kind of experimental diabetes did not induce any significant light microscopical or electron microscopical changes of the villi, the crypts, or the absorptive cells. It was concluded that the adaptive capacity of the structure of the small intestine mucosa to short term experimental diabetes is more pronounced in the jejunum than in the duodenum, and that the adaptive response also includes alterations in the structure of the absorptive cells.

Animals↗

PubMed1989

Changing health beliefs and behaviors of resettled Laotian refugees: ethnic variation in adaptation.

This paper describes traditional and changing health-related beliefs and behaviors of ethnic Lao refugees now resettled in the United States and how these compare with those of other ethnic groups of resettled refugees from Southeast Asia. New data are presented for Southeast Asian refugees resettled in Franklin County, Ohio, including resettlement agency utilization statistics for refugees of each local ethnic group, which reveal that Laotian refugees have the most persistent use of resettlement agency services. The results of in-depth, open ended interviews with members of the Franklin County Lao community are also presented. The interview data pertain to Lao self-perceived health problems and health care options as well as their health beliefs and practices, both traditionally in Laos and as these have changed with refugee flight and resettlement. These data are compared with the results of the limited relevant health-related research on other ethnic groups of Southeast Asian refugees, revealing that Laotian refugees rely to a relatively great extent on the Western biomedical system. It is suggested that the nature of Lao refugee adaptation is due to the continuation of traditional patron-client relationships in the U.S., with Lao patrons referring their refugee clients to the services of agencies and the biomedical establishment.

Adolescent↗

PubMed1990

Class II furcations treated by guided tissue regeneration in humans: case reports.

In the cases reported here, the response of Class II mandibular molar furcation defects to guided tissue regeneration (GTR) versus sham operation was evaluated. Base-line information, including probing pocket depth (PD) and clinical attachment level (CAL) measurements, was recorded after completion of the hygienic phase. Eleven experimental and six control furcations, randomly assigned, are included in this report. The furcations were surgically exposed, using a flap approach and the areas were debrided. On the experimental teeth, Gore-Tex periodontal material was adapted and sutured, using a suspensory suture. The flaps were then sutured tightly, assuring complete coverage to the material. For 1 month all patients were seen weekly and rinsed their mouths with an 0.12% chlorhexidine solution daily. After 4 to 6 weeks the Gore-Tex membranes were removed. Clinical measurements were repeated at 3 and 6 months following surgery. Changes from baseline in PD and CAL were calculated for each case. Results indicated that PD measurements were reduced by both procedures, but the reduction was better for GTR at 3 and 6 months. At six months the test sites showed 2.8 +/- 1.0 mm pocket reduction, while the control sites showed an average of 1.6 +/- 0.9 mm reduction in pocket depth. CAL recordings were improved by both treatments, but were better for GTR at 6 months, with an average gain in CAL of 1.8 mm for the GTR and 0.6 mm for the controls. These cases in which GTR was compared to sham-operated controls indicate that GTR can improve the response to therapy of Class II furcation defects.

Adult↗

PubMed2001

Autotransplantation modulates ileal enteroendocrine cell expression in the pig.

BACKGROUND: Enteroendocrine cell-derived peptides modulate postresectional small bowel adaptation, which may be attenuated by transplantation. We investigated whether autotransplantation modulates the number and distribution of ileal enteroendocrine cells in pigs with proximal small bowel resection. MATERIALS AND METHODS: Fifteen pigs were assigned into either small intestinal transection or 75% proximal small intestinal resection with or without autotransplantation of the remaining ileum. After 14 weeks the number and subtype distribution of enteroendocrine cells, crypt cell proliferation, and mucosal histology were analyzed from the proximal and distal ends of the remaining ileum. RESULTS: When compared to resected controls, autotransplantation of the ileum decreased the absolute (P < 0.05 in proximal ileum) and proportional (P < 0.05 in distal ileum) crypt enteroendocrine cell number. In addition, autotransplantation reduced somatostatin and glicentin expressing cell counts and abolished the proximodistal gradient of the enteroendocrine cell number. When compared to transected controls, villus height, crypt depth, number of proliferating crypt cells, and crypt cell proliferation index increased after the proximal resection (P < 0.05 in all except in crypt depth and proliferation index of the distal ileum) but remained virtually unchanged after autotransplantation of the ileal remnant. CONCLUSIONS: Autotransplantation decreases the crypt enteroendocrine cell number and alters their proximodistal and subtype distribution in the remaining ileum in pigs with proximal small bowel resection. These alterations are associated with attenuated adaptive response of the autotransplanted ileum.

Anastomosis, Surgical↗

PubMed2006

Latino farmworker perceptions of the risk factors for occupational skin disease.

BACKGROUND: Farmworkers in the US constitute a medically underserved population at substantial risk for numerous environmental and occupational health problems. Most US farmworkers are Latino. Skin disease is one health problem to which farmworkers are particularly vulnerable. Interventions to reduce skin disease must be adapted to farmworkers' understanding of such disease, including their beliefs or knowledge of risk factors for skin disease. METHODS: Structured by the Explanatory Models of Illness framework, this analysis uses a qualitative design based on in-depth interviews with 30 Latino farmworkers (6 females, 24 males) to determine beliefs and perceptions of the causes of common occupational skin diseases in this population. Computer assisted, systematic procedures are used to analyze the verbatim transcripts of these interviews. RESULTS: Skin disease is a major concern among farmworkers because it affects work, social interaction, and other aspects of their lives. Farmworker beliefs and perceptions of skin disease causation can be integrated into a general model in which perceived risk factors include sun and heat, chemicals, plants, insects, moisture, hygiene, and contagion. Each of these factors is moderated by the individual's personal susceptibility to that cause. The interaction or combination of two or more factors is thought to amplify their individual effects. CONCLUSIONS: The farmworker model of skin disease causation suggests important content for health education to reduce skin disease among farmworkers.

Adolescent↗

PubMed2006

Computer program for automated sleep depth estimation.

In this article, we present a new implementation of an amplitude-independent method for continuous-scale sleep depth estimation. Having been implemented as an add-on analysis module under commercially available biosignal recording and analysis software, it can be easily applied in clinical routine. The software gives the user full freedom to change all the analysis parameters inside theoretical limits. Computational sleep depth profiles produced by the presented software compare favourably with visual classifications. Future work will concentrate on systematic optimization of analysis parameters, further evaluation of the method with disturbed sleep and application of the method for automated adaptive sleep analysis.

Electronic Data Processing↗

PubMed2006

Sex preparation and diaphragm acceptability in sex work in Nairobi, Kenya.

BACKGROUND: Women in sex work stand to benefit if the contraceptive diaphragm alone or combined with a microbicide proves to be an effective barrier method against HIV and sexually transmissible infection (STI). Currently, contraceptive diaphragm users are advised to leave the diaphragm in situ without concomitant use of other intravaginal substances for at least 6 h after intercourse. METHODS: We conducted in-depth interviews on sexual behaviour including post-coital intravaginal practices with 36 women in sex work and 26 of their clients and held two focus-group discussions, each with 10 women. RESULTS: The women described adapting several potentially harmful substances, such as cloth and soapy water, for post-coital vaginal use to ensure personal hygiene, disease prevention and client pleasure. Some wanted to clean themselves and remove the diaphragm early, fearing exposure to HIV infection for themselves and their subsequent clients. Clients indicated their desire for 'dry sex', vaginal cleanliness and reduced risk of infection through vaginal cleaning. CONCLUSIONS: The diaphragm as a female-controlled barrier method for HIV/STI prevention may have limited acceptability among women in sex work if its effectiveness depends on a 6-h post-coital wait before removal, along with avoidance of concomitant use of intravaginal substances. In keeping with the beliefs of the the female sex workers and their needs and practices, alternative intravaginal substances and modes of insertion that will not disrupt vaginal flora, injure vaginal epithelium, damage the diaphragm or counteract potentially beneficial effects of microbicides are needed. The possibility of removing the diaphragm sooner than the recommended 6 h for contraception should be further studied.

Adolescent↗

PubMed1997

Desulfovibrio profundus sp. nov., a novel barophilic sulfate-reducing bacterium from deep sediment layers in the Japan Sea.

Several strains of a strictly anaerobic, vibrio-shaped or sigmoid, sulfate-reducing bacterium were isolated from deep marine sediments (depth, 80 and 500 m) obtained from the Japan Sea (Ocean Drilling Program Leg 128, site 798B). This bacterium was identified as a member of the genus Desulfovibrio on the basis of the presence of desulfoviridin and characteristic phospholipid fatty acids (iso 17:1 omega 7 and iso 15:0), the small number of growth substrates utilized (lactate, pyruvate, and hydrogen), and 16S rRNA gene sequence analysis data. Based on data for 16S rRNA sequences (1,369 bp), all of the Japan Sea strains were identical to each other and were most closely related to Desulfovibrio salexigens and less closely related to Desulfovibrio desulfuricans (levels of similarity, 91 and 89.6%, respectively). There were, however, considerable phenotypic differences (in temperatures, pressures, and salinities tolerated, growth substrates, and electron donors) between the Japan Sea isolates and the type strains of previously described desulfovibrios, as well as important differences among the Japan Sea isolates. The Japan Sea isolates were active (with sulfide production) over a wide temperature range (15 to 65 degrees C) and a wide sodium chloride concentration range (0.2 to 10%) (moderate halophile), and they were barophiles that were active at pressures up to about 40 MPa (400 atm). The optimum pressures for activity corresponded to the calculated pressures at the depths from which the organisms were isolated (for isolates obtained at depths of 80 and 500 m the optimum activities occurred at 10 and 15 MPa, respectively [100 and 150 atm, respectively]). This confirms that the organisms came from deep sediments and indicates that they are well-adapted for deep sediment conditions, which is consistent with other characteristics (utilization of hydrogen, fermentation, and utilization of ferric iron and organic sulfonates as electron acceptors). We propose that Japan Sea isolate 500-1 is the type strain of a new species, Desulfovibrio profundus.

Base Sequence↗

PubMed1992

Abscisic Acid increases terrestrial plant cell resistance to hydrostatic pressure.

Cells of the terrestrial plant species bromegrass (Bromus inermis L.) are not naturally adapted to withstand the hydrostatic pressures encountered in aquatic environments. However, after treatment with the natural plant growth hormone abscisic acid (75 micromolar), bromegrass cells survived a hydrostatic pressure of 101.3 megapascals, approximating the limits of ocean depth (10,860 m). The increased resistance to hydrostatic pressure from 1 to 7 days of abscisic acid treatment paralleled the induced elevation of cell tolerance to freezing stress.

Journal Article↗

PubMed1991

An ellipsoidal representation of human hand anthropometry.

The goal of this study was to collect anthropometric data that describe the geometry of the surface of the hand and to model this anthropometry as a function of gross external hand measurements. The depth and breadth of each segment of the hand were measured at points that were spaced at approximately equal distances between the joints of the hand. Linear models using hand breadth as the independent variable explained from 12% to 47% of the variation in segment breadths and from 6% to 74% in segment depths. Ellipsoids are used in biomechanical models as an efficient mathematical description of the shape of kinematic segments for use in the determination of contact with other objects. Therefore the primary objectives of this study were to approximate the semiaxis dimensions for these hand segment contact bodies using a linear model of the gross anthropometry and to evaluate the accuracy with which ellipsoids describe the geometry of the hand segments. Graphical comparisons showed that differences between the ellipsoidal approximations and the breadth and depth measurements were largest near the joints. Data collected in this study could be used to create a set of overlapping ellipsoids that would provide a more accurate representation of hand geometry, and this representation could be adapted to biomechanical models that use ellipsoids to define segment geometry.

Adult↗

PubMed2000

Isoflurane anesthesia for guinea pigs (Cavia porcella) in a stereotaxic surgical apparatus.

Isoflurane (1-chloro-2,2,2-trifluoroethyl difluoromethyl ether) is a potent general anesthetic agent that is highly adaptable to use in small laboratory animal species. Respiratory delivery is easily accomplished in these animals, even during restraint in a stereotaxic apparatus. The ease of administration, high predictability of action, and ability to finely control the depth of anesthesia make isoflurane anesthesia far superior to regimes involving injectable anesthetics. The wide margin of safety of isoflurane is a key indicator of the superiority of this product to all other anesthetic agents. The initial cost associated with the delivery system is a drawback, but the reliability and safety factors outweigh the hardware costs.

Anesthesia, Inhalation↗