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Results for “depth adaptation”

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PubMed2000

UV transmission measurements of small skin specimens with special quartz cuvettes.

BACKGROUND: The penetration of different wavelengths of UV radiation through human skin is of major importance, especially for the determination of photoprotective properties of sunscreens and UV-protective clothes. OBJECTIVE: In this study we present a new method for the measurement of UV transmission through small skin specimens. METHODS: The transmission measurements were performed by using a UV spectrophotometer with an integrating sphere operating in the wavelength range of 280-390 nm. For the skin samples, special quartz glass cuvettes were developed which allowed measurements for very thin and small skin specimens. Furthermore, the cuvettes prevented dehydration of the specimens and guaranteed, by using an additional diaphragm, that the transmission data were derived solely from the small skin specimen examined. Specimens measuring 8 x 3 mm(2) with a thickness of 0.3 mm (histometric and sonographic control) were taken from the thighs of 10 subjects via shave biopsy. RESULTS: In the UVA range (315-390 nm) we obtained a mean transmission of 4.6% and for the UVB range (280-315 nm) of 0.9%. No significant (p >0.14) difference of UV transmission was found between the individual skin specimens. CONCLUSION: This new method seems to be well suitable for UV transmission measurements of small skin specimens. As UVA radiation has a much deeper penetration depth and in in vivo situations dermal hemoglobin could have an effect on UV penetration, the present method is better suitable for the investigation of UVB-induced biological adaptation mechanisms and the impact of topical agents on UVB transmission of the epidermis.

Aged↗

PubMed2006

Salivary aspartate aminotransferase, alanine aminotransferase and alkaline phosphatase: possible markers in periodontal diseases?

BACKGROUND: Saliva can be used as a diagnostic fluid in medicine. Components of saliva proposed as disease markers include enzymes (alkaline phosphatase, esterase, glucuronidase, aminopeptidase), immunoglobulins (IgA, IgG), and hormones (steroid hormones). Many of these salivary components appeared to be useful biochemical markers of the evolution of periodontal disease, for which salivary analysis can offer a cost-effective approach for monitoring the disease. The salivary components proposed as markers for periodontal disease activity are aspartate aminotransferase (AST), alkaline phosphatase (ALP), aminopeptidases, and glucuronidases. The purpose of our study was to illustrate the influence of periodontal disease on the level of salivary AST, alanine aminotransferase (ALT) and ALP. METHODS: All clinical periodontal examinations were performed by the same periodontist. All patients included in the study presented a probing depth >5 mm, bleeding on probing and alveolar bone loss >40%. Salivary AST, ALT and ALP activities were measured using DiaSys analysis kits from Diagnostic Systems. The methods were adapted for saliva. RESULTS: Salivary AST activity in patients with periodontal disease was significantly increased (p<0.01) (median 81.75+/-23 U/L) compared with controls (15.25+/-10.5 U/L). Salivary ALT activity was not significantly modified in saliva from patients with periodontal disease compared with the control group. Our results showed a significant (p<0.01) increase in salivary ALP activity (34.38+/-1.5 U/L) in patients with periodontal disease compared with controls (6.6+/-4.2 U/L). CONCLUSIONS: Our results revealed that periodontal destruction such as periodontal pockets, gingival bleeding and suppuration are related to higher ALP and AST levels in saliva. Salivary AST could be used as a useful marker for monitoring periodontal disease. The increase in salivary ALP activity in periodontitis demonstrated could be associated with alveolar bone loss, a key feature of periodontal disease. More studies are necessary to evaluate which specific clinical, microbiological and histological characteristics of periodontal disease are associated with elevated levels of AST and ALP in saliva.

Adult↗

PubMed2006

[A study on the adapting process of nursing students to problem based learning].

PURPOSE: The purpose of the study was to identify the adaptation process to problem based learning(PBL) among nursing students who have experienced PBL classes for two years. METHOD: Data was collected from 11 nursing students with in-depth interviews and direct observation of their PBL experiences by a researcher who has been a facilitator for PBL class for 3 years. Immediately after the interviews all of them were transcribed. It was analyzed by the Ground theory of Corbin and Strauss. RESULTS: A derived core category was 'Acquiring PBL'. 4 stages of the acquiring process were derived and written in time sequence: chaos, confusion, beginning insight, and achievement stage. CONCLUSION: The results will not only expand understanding of the students for the facilitator and school which has adopted PBL but also provide information to develop an orientation program for PBL. Further research on the facilitator's role experiences is recommended.

Adult↗

PubMed1986

[Face masks for radiotherapy of head and neck tumors: comparative tests of different materials].

A most precise immobilisation of the patient's head is indispensable in order to reach a high degree of exactness and reproducibility in radiotherapy of malignant head and neck tumors. Face masks made of different synthetic materials have proved to be a simple and economical solution for this problem. Based on our own experiences with "Baycast Longuettes" (manufacturing firm: Johnson & Johnson, Düsseldorf), eleven substances have been tested in the phantom (compound of plaster and synthetic resin, thermoplast, polyurethane foam, compounds of cotton and synthetic resin, and fibre glass compounds). An appropriate material was "Hexcelite" (manufacturing firm: Medimex, Hamburg), a reticulated thermoplast which after warming up can be easily adapted to the patient's face and which guarantees a very good fixation of the head. As compared to solid masks, there is only a slight superposition of the depth dose of Co-60 gamma radiation by secondary electrons from the mask material, so that an increased rate of radiogenic dermatitides is not to be expected.

Casts, Surgical↗

PubMed1981

[Functional aniseikonia: clinical study of 110 cases (author's transl)].

A clinical study was conducted in 110 cases of subjective aniseikonia, a syndrome that is often neglected. After in practice summarizing the different distortions composing the phenomenon of aniseikonia, a description of the prototype apparatus used for the experiments is given: it is eikonometric stereo-projector the originality of which lies in the measuring system, constituted by the projected stereograms. Three parameters were studied: depth-perception, peerception threshold of anseiikonic disparity, and value of the found aniseikonia. The results are presented in relation to 3 groups of subjects: 14 emmetropic, 32 isometropic, and 64 anisometropic, 32 isometropic, and 64 anisometropic patients, including 24 monocular aphakic. The author shows the advantage of contact lens correction in the last cases: with an average of 3.5 p. cent, the found aniseikonia was always inferior to 6 p. cent and to the theorectical levels currently accepted. Finally, the phenomenon of "cortical malleability" arises in the adaptation of the patient to his optical correction and could regularly and progressively be increased.

Aniseikonia↗

PubMed1990

Systemic factors are trophic in bypassed rat small intestine in the absence of luminal contents.

Mucosal histology, crypt cell proliferation and brush border enzymes were measured in rats with varying degrees of jejunoileal bypass, in order to compare the effect of systemic and luminal factors on adaptive growth and differentiation (brush border enzymes) in small intestinal epithelium. Eighty five percent jejunoileal bypass caused a functional short gut; in intestine remaining in continuity there were significant increases in segmental weight, villus area and crypt depth, compared with sham operated controls and 25% jejunoileal bypass rats. Despite villus cell hyperplasia in 85% bypass rats, mucosal sucrase and alkaline phosphatase fell in jejunum and remained low in ileum, while leucine amino peptidase rose in ileum. There was a significant fall in villus area (p less than 0.01) and crypt cell production (p less than 0.001) in self emptying loops of 25% bypass rats not exposed to luminal contents compared with control segments of sham operated rats. In contrast, self emptying loops of 85% bypass rats were not atrophied despite the much greater distance from luminal nutrients; the villus area (p less than 0.01) and crypt cell production (p less than 0.005) were higher than in 25% bypass rats, and at least as great as in sham operated rats. These results indicate that adaptive hyperplasia has a variable effect on expression of brush border enzymes which might reflect villus cell immaturity. The atrophic effect of diversion of luminal contents can be counteracted by systemic growth factors released as part of the adaptive response; thus systemic growth factors are not dependent on a permissive effect of luminal contents.

Adaptation, Physiological↗

PubMed1991

Neurological assessment: adaptations for special populations with mental retardation.

The incidence of mental retardation in the United States is approximately 125,000 births per year. Recent changes in government regulations necessitate that nurses caring for mentally retarded persons perform physical appraisals. These in-depth appraisals are a new skill for many nurses caring for the retarded and the routine neurological assessment processes must be modified in order to meet the special needs and behaviors of the mentally retarded population. This article provides examples of how a functional abilities approach to the neurological appraisal process can be modified. Further, two scenarios are presented to demonstrate how neurological data can be obtained from observing an individual's activities of daily living.

Activities of Daily Living↗

PubMed1981

What is intensive psychotherapy?

The fundamental practical premises underlying the practice of intensive psychotherapy are investigated in this article. Based on ego-psychology orientation, mental illness is classified in terms of premature ego development, ego distortions, ego deviations, ego regression, and ego defects. General healing factors are reviewed, first as presented, for example, in Frank's "demoralization hypothesis." The forms of psychotherapy may be classified in terms of how they approach the problem of demoralization and failure of ego adaptation, into counseling, supportive, reeducative, and psychoanalytic. Intensive psychotherapy is conceived of as a derivative discipline of psychoanalysis. It is different in that the goals are more limited, and active interventions ("parameters" or "departures") are often unavoidably called for, making it less "neat and orderly," more taxing on the therapist, and more of an art. It is similar in that an emphasis on the patients' spontaneous associations and an attempt to retain analytic neutrality as much as possible leads to the formation of transferences and resistances which may be dealt with by interpretation. However, full-blown transference neuroses usually do not form as in classical psychoanalysis, limiting the depth and extensiveness of the procedure. Intensive psychotherapy is the treatment of choice for selected cases of schizophrenia, severe personality disorders, and psychosomatic conditions.

Adaptation, Psychological↗

PubMed1990

Origin of negative potentials in the light-adapted ERG of cat retina.

1. The light-adapted diffuse-flash electroretinogram (ERG) in the cat exhibits two prominent negative components: a sustained negative potential during illumination and a negative-going OFF response. We investigated their intraretinal origins and found that the sustained component originates from the rod photoreceptors, whereas the OFF response represents a combination of the return to base line of the rod-receptor potential, the offset of PII (rod and cone), and a cone-dependent OFF response originating proximal to the photoreceptors at very high background levels. 2. The ERG, evoked in response to diffuse illumination of the light- and dark-adapted cat retina, was recorded between a chlorided silver wire in the vitreous and a plate behind the eye. Extracellular field potentials were recorded simultaneously with a microelectrode placed intraretinally at different retinal depths. 3. The sustained negative potential and the negative OFF response were not the M-wave ON and OFF responses of proximal retina, despite an overall resemblance in form and time course: 1) the M-wave was spatially tuned, whereas the ERG components were not; 2) tetrodotoxin (TTX) (3.8-microM vitreal concentration) did not alter the M-wave, but it reduced the ERG OFF response; 3) picrotoxin (0.14 mM, after TTX) enhanced the M-wave but did not affect the negative ERG; and 4) 2-amino-4-phosphonobutyric acid (APB; 0.95 mM) removed the M-wave ON response, and aspartate (43 mM) removed the M-wave OFF response, in addition, while the sustained negative potential persisted. 4. The sustained negative potential was not slow PIII, the neural retinal component of the c-wave, a Müller cell response to the photoreceptor-dependent light-evoked decrease in subretinal extracellular K+ concentration [( K+]o). Although Ba2+ (repeated injections of 4-5 mM), a K+ conductance blocker, eliminated slow PIII, it did not remove the sustained negative potential. We concluded that the sustained negative potential was a photoreceptor potential, and the spectral sensitivity of the response indicated that it arose from rods. 5. The contribution of the rod-receptor potential to the ERG depended on background illumination. It was a sustained potential for a range of backgrounds near and 1 or 2 log units above the illumination that saturates rod-driven responses in cat (8.2 log quanta.deg-2.s-1). At lower background intensities, it appeared only as a dip between the b- and c-waves, the b-wave trough, which also was present in fully dark-adapted responses.(ABSTRACT TRUNCATED AT 400 WORDS)

Adaptation, Ocular↗

PubMed1994

Drill guide for hydroxyapatite implants.

A drill guide to facilitate the second drilling of hydroxyapatite orbital implants is presented. The drill guide is adaptable to various drill types. It is nontraumatic and provides excellent, one-handed fixation, eliminating the need for an assistant. It allows for consistent, straight drilling to a predetermined depth and, because it is encased, it protects the patient from injury. The drill guide has been used on 30 patients and is without untoward effects.

Durapatite↗

PubMed1984

Children coping with impaired appearance: social and psychologic influences.

Coping with impaired appearance presents difficulties for children. This study is based on interviews of children with vitiligo, a disfiguring disorder that involves depigmentation of the skin, and focuses on social and psychologic factors that predict effectiveness of coping. Age plays an extremely important part in adjustment, with the junior high school years especially traumatic. Change of location or situation also is a predictor of stress. Children who develop other competencies that build self-esteem cope well with the disorder. These and other factors are explored in depth, and strategies for helping child patients with disfiguring disorders are suggested.

Achievement↗

PubMed2005

Responses of Israeli HMOs to environmental change following the National Health Insurance Law: Opening the black box.

Managed competition was introduced into the Israeli health care system with the enactment of the National Health Insurance (NHI) Law of 1995, which radically transformed health management organizations' (HMO) regulatory and competitive environments. We conducted an in-depth, qualitative analysis of the strategies developed by two Israeli HMOs in response to this change, and developed the concept of a "strategic repertoire" to integrate diverse theories of organizational adaptation to environmental change. Although the responses of these organizations to managed competition were broadly comparable, they diverged from one another in important ways. Our analysis highlights how the interaction among organizational history, managerial choice, and environmental constraints creates divergence in organizational responses to national policy initiatives. Policy implications arising from the findings include ways of anticipating unintended consequences of policy initiatives, such as involving provider organizations in the structuring of reform, or simulating their response in advance, based on expert knowledge of their strategic repertoires; and the need to include mechanisms for obtaining feedback on organizational responses in the implementation of reform. This will facilitate the adjustment of program regulations and incentives in response to emerging practices.

Economic Competition↗

PubMed2005

Surround-induced foveal afterimage pulsation: evidence for a long-range neural effect.

We demonstrate that an afterimage resulting from a strong foveal light flash can be made to pulsate by luminance modulation of a surrounding annulus as far as 8 deg away. Afterimage pulsation persists even if all artifacts due to pupil size, stray light and simultaneous contrast are ruled out. This suggests an origin by a long-range neural process acting from the remote surround. The effect is interpreted in terms of an adaptive gain control optimizing the responses of visual cells.

Adult↗

PubMed2005

[Imaging of the anterior eye chamber with optical coherence tomography].

BACKGROUND: Optical coherence tomography (OCT) represents a high-resolution diagnostic method which can be used to precisely image the anterior eye segment. Further developments in scanning technology and data evaluation allowed to visualize the entire anterior eye segment in one image, and the purpose of this study was to clinically evaluate this new system. PATIENTS AND METHODS: The studied OCT system was adapted to a slit-lamp and allowed us to image the anterior segment with an axial resolution of 10 microm at a scanning rate of 200 Hz with a depth of 7 mm and a maximal width of 15 mm. In selected cases the clinical value of anterior segment OCT was assessed. The reproducibility and level of agreement of anterior chamber depth measurements were assessed during the preoperative examination in 49 cataract surgery patients and compared to ultrasound (US) biometry (10 MHz). RESULTS: The studied anterior segment OCT allowed the cross-sectional imaging of the entire anterior eye segment. Changes of the anterior chamber before and after cataract surgery or surgical iridectomy were visualised. Furthermore, the findings of the anterior chamber after implantation of an iris-fixated intraocular lens (IOL) and an iris prosthetic system could be assessed. The reproducibility of the anterior chamber depth measurement was +/- 22 microm (OCT) and +/- 76 microm (US). The mean difference between optical and acoustic values was 1 microm (0.03 % p = 0.921) and the limits of agreement (95 % confidence interval) were 260 microm (8.58 %). CONCLUSIONS: The anterior segment OCT proved to be a helpful diagnostic method. The cross-sectional visualisation of the entire anterior chamber allowed us to assess important values for the implantation of iris-fixated IOL and other changes after surgical procedures. The resolution and reproducibility were higher than for conventional ultrasound biometry.

Aged↗

PubMedDate not supplied

Recovery from alcoholism: a spiritual journey.

The purpose of this study was to discover the internal aspects of change in persons who are doing well living without alcohol. The heuristic research method, a qualitative phenomenological design, was used to investigate the experience of recovery. Eight recovering alcoholics were interviewed in depth. The process of recovery reflected a mythological journey comprising a departure from the shadowland of drinking, initiation into the world of sobriety, and knowledge gained along the way. New adaptive strategies were acquired, including strengthening the will, training the mind, and exercising spiritual qualities in one's daily life. The profile of doing well in recovery also reflected self-acceptance and an ongoing search for connecting with the transpersonal realm.

Adaptation, Psychological↗

PubMed2006

Intensity correction of fluorescent confocal laser scanning microscope images by mean-weight filtering.

This paper addresses the problem of intensity correction of fluorescent confocal laser scanning microscope images. Confocal laser scanning microscope images are frequently used in medicine for obtaining 3D information about specimen structures by imaging a set of 2D cross sections and performing 3D volume reconstruction afterwards. However, 2D images acquired from fluorescent confocal laser scanning microscope images demonstrate significant intensity heterogeneity, for example, due to photo-bleaching and fluorescent attenuation in depth. We developed an intensity heterogeneity correction technique that (a) adjusts the intensity heterogeneity of 2D images, (b) preserves fine structural details and (c) enhances image contrast, by performing spatially adaptive mean-weight filtering. Our solution is obtained by formulating an optimization problem, followed by filter design and automated selection of filtering parameters. The proposed filtering method is experimentally compared with several existing techniques by using four quality metrics: contrast, intensity heterogeneity (entropy) in a low frequency domain, intensity distortion in a high frequency domain and saturation. Based on our experiments and the four quality metrics, the developed mean-weight filtering outperforms other intensity correction methods by at least a factor of 1.5 when applied to fluorescent confocal laser scanning microscope images.

Biometry↗

PubMed1987

Potentials evoked by the sinusoidal modulation of the amplitude or frequency of a tone.

Steady state responses to the sinusoidal modulation of the amplitude or frequency of a tone were recorded from the human scalp. For both amplitude modulation (AM) and frequency modulation (FM), the responses were most consistent at modulation frequencies between 30 and 50 Hz. However, reliable responses could also be recorded at lower frequencies, particularly at 2-5 Hz for AM and at 3-7 Hz for FM. With increasing modulation depth at 40 Hz, both the AM and FM response increased in amplitude, but the AM response tended to saturate at large modulation depths. Neither response showed any significant change in phase with changes in modulation depth. Both responses increased in amplitude and decreased in phase delay with increasing intensity of the carrier tone, the FM response showing some saturation of amplitude at high intensities. Both responses could be recorded at modulation depths close to the subjective threshold for detecting the modulation and at intensities close to the subjective threshold for hearing the stimulus. The responses were variable but did not consistently adapt over periods of 10 min. The 40-Hz AM and FM responses appear to originate in the same generator, this generator being activated by separate auditory systems that detect changes in either amplitude or frequency.

Acoustic Stimulation↗

PubMed1990

Hydrocarbon mineralization in sediments and plasmid incidence in sediment bacteria from the campeche bank.

Rates of degradation of radiolabeled hydrocarbons and incidence of bacterial plasmid DNA were investigated in sediment samples collected from the Campeche Bank, Gulf of Mexico, site of an offshore oil field containing several petroleum platforms. Overall rates of mineralization of [C]hexadecane and [C]phenanthrene measured for sediments were negligible; <1% of the substrate was converted to CO(2) in all cases. Low mineralization rates are ascribed to nutrient limitations and to lack of adaptation by microbial communities to hydrocarbon contaminants. Plasmid frequency data for sediment bacteria similarly showed no correlation with proximity to the oil field, but, instead, showed correlation with water column depth at each sampling site. Significant differences between sites were observed for proportion of isolates carrying single or multiple plasmids and mean number of plasmids per isolate, each of which increased as a function of depth.

Journal Article↗