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Results for “reflection”

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PubMed2005

All-reflective snapshot hyperspectral imager for ultraviolet and infrared applications.

Snapshot hyperspectral imaging simultaneously acquires spatial and spectral information about a scene. We report on the first, to our knowledge, all-reflective snapshot hyperspectral imager in the form of a computed tomography imaging spectrometer (CTIS). The reflective design allows for instrument simplicity for applications in the ultraviolet and infrared. To realize a CTIS in a reflective Offner configuration, a reflective two-dimensional computer-generated hologram grating is fabricated on a convex spherical substrate by direct-write electron-beam lithography. Furthermore, a reconfigurable reflective field stop is implemented with a micromirror array to provide high-contrast spatial-spectral filtering, region-of-interest selection, and spatial structure formation.

Journal Article↗

PubMed2006

Influence of the third-order parameter on diffuse reflectance at small source-detector separations.

Spatially resolved reflectance close to source has received a great deal of attention recently. This research is considered to develop a new noninvasive technique for measuring the optical properties of biological media. Using Monte Carlo simulations, we investigated the influence of third-order parameter 5 on diffuse reflectance and found that the reflectance decreased with an increase of delta at a short source-detector separation of approximately 0.7-2 transport mean free paths. We show that the effects of two parameters, y and second-order parameter delta, on the reflectance are contrary. As a result the influence of the second-order parameter y on the reflectance is irregular when the condition delta delta<<delta gamma is not satisfied.

Algorithms↗

PubMed2006

Using the Kramers-Kronig method to determine optical constants and evaluating its suitability as a linear transform for near-normal front-surface reflectance spectra.

In this paper, the suitability of using the Kramers-Kronig transform to routinely extract optical constants from near-normal incidence reflectance spectra of solids and liquids is demonstrated. In addition, the possibility of utilizing the Kramers-Kronig transform as a linearizing transform for near-normal incidence reflectance spectra is investigated. Also, several commercial Kramers-Kronig software packages were utilized in determining the optical constants from the near-normal incidence reflectance of Plexiglas. Unexpectedly, the results produced by the various packages differed significantly. The near-normal reflectance of water was measured, the Kramers-Kronig transform was applied to extract the optical constants of water, and the result was compared to values found in the literature. Furthermore, the Kramers-Kronig transforms of near-normal incidence reflectance spectra of various concentrations of sugar in water were calculated to evaluate its use as a linearizing transform for quantitative applications.

Journal Article↗

PubMed1990

The effect of meconium on neonatal and fetal reflectance pulse oximetry.

Reflectance probes are being developed for neonatal use and obstetricians are beginning to use reflectance pulse oximetry to monitor the fetus. When a reflectance probe was used to monitor the arterial oxygen saturation of a baby whose skin was stained with meconium an artificially low result was obtained. This is because meconium absorbs more red than infra-red light and acts as a red light filter between the vascular bed and the probe. This effect may be reproduced by interposing a red filter between a reflectance pulse oximetry probe and the skin. Obstetricians who use a pulse oximeter to assess the fetus through intact membranes will record an erroneously low result if they are stained with meconium. Similarly neonatologists should avoid placing a reflectance pulse oximetry probe on babies skin which is stained with meconium.

False Negative Reactions↗

PubMed2001

Reflective-impulsive style and conceptual tempo in a gross motor task.

The reflective-impulsive construct refers to responses made slowly or quickly in a situation with high uncertainty. Children who are labeled "reflective" take a longer time to respond and make few errors, whereas "impulsive" children are fast and inaccurate. Although the validity of the test and the definition of reflective-impulsive style are well accepted, whether such respond fast or slow to all tasks is questioned. Some children do not fit the dichotomy. Two other groups arise, the fast-accurate and the slow-inaccurate. The response styles of 86 boys, ages 5, 7, and 9 years performing a gross motor task, i.e., hitting a ball with a racquet, were studied. Analysis indicated that the slowest children on the Matching Familiar Figures Test can be faster than the fastest ones and remain more accurate. As the definition of the reflective-impulsive style is based on time, the reflective ones might better be viewed as children who can adapt the response time to the context and thus be more efficient at problem-solving.

Child↗

PubMed2004

Reflectance spectroscopy of clotting blood: a description of the time-dependent behavior.

CONTEXT: Research into whether cyclooxygenase-2 (COX-2) inhibitors affect thrombosis has been hampered by the lack of a specific assay. Erythrocytes modulate the effect of aspirin on platelets, which suggests that tests of whole blood clotting may be more sensitive. OBJECTIVES: To determine whether reflectance spectroscopy of clotting blood generates useful information about coagulation and whether it shows an effect of COX-2 inhibitors. DESIGN: A survey of 14 adults examined the range of phenomena demonstrated by reflectance spectroscopy. These phenomena were compared before and after treatment with a COX-2 inhibitor in 4 subjects. SETTING: Out-patient clinic. MAIN OUTCOME MEASURE: Reflected light intensity was measured from blood as it clotted in a cuvette thermostated at 37 degrees C. RESULTS: The survey of healthy adults showed that the time course of reflected light intensity is similar at all wavelengths and may be divided into 4 stages: a monotonic decrease, a sigmoidal increase, a linear region, and a terminal phase. Clot formation as determined by tube inversion occurs at the transition between the first and second phases; the sigmoidal increase cannot be due to fibrin polymerization. The terminal phase coincides with clot retraction. Similar results are obtained in native whole blood and in recalcified citrated blood. Cyclooxygenase-2 inhibitors have an intrinsic effect on the sigmoidal increase ex vivo (P <.001). CONCLUSIONS: Reflectance spectroscopy generates unique information about clotting blood. It is feasible to use anticoagulated blood to elucidate the events underlying the time course and to investigate the effects of COX-2 inhibitors.

Adolescent↗

PubMedDate not supplied

Caring for a patient with COPD: a reflective account.

Reflective practice has been a familiar topic in nursing journals and the term is regularly used in professional nursing practice. However, it was not until I used Johns' (1994) model to analyse and explore my feelings and actions in daily practice that I fully understood the concept of reflective practice and discovered how it can enhance professional development. This article describes a reflective experience related to caring for a patient with chronic obstructive pulmonary disease in the community. The professional implications of this experience are explored through reflection. This exploration raised two main issues: the development of a therapeutic nurse-patient relationship and the feelings of guilt experienced when reflecting on whether I had let the patient down when most needed, in the final stages of her life.

Attitude of Health Personnel↗

PubMedDate not supplied

The reflective patient: intrapersonal care.

AIM: To consider the relevance and potential role of patient reflection in their overall healthcare experience. METHOD: In-depth, unstructured, qualitative interviews were conducted with 19 patients due to have elective orthopaedic surgery. A longitudinal study design was used, covering the period from a few weeks before to approximately three months after surgery. Forty five interviews were conducted in total. RESULTS: The degree to which participants expressed evidence of reflection and the nature of their reflections varied. Much reflection focused on remaining unknowns and lingering queries. Participants seemed to be trying to work towards an acceptable interpretation of their experiences. This interpretation then fed into their experience of, and responses to, their care. CONCLUSION: Intrapersonal care is suggested as a way of conceptualizing the patient's process of reflection. This complements interpersonal care given by nurses. Intrapersonal care must be well supported to realise its potential therapeutic effect.

Attitude to Health↗

PubMedDate not supplied

Using structured reflection on a critical incident to develop a professional portfolio.

This article demonstrates reflective practice by examining a critical incident that took place at a children's burns unit. The development of reflective skills is documented using a method of structured reflection. The concepts of aesthetics, personal knowing, empirics and ethics are considered to reflect on the critical incident. Reflection is considered in the context of developing a portfolio to analyse and demonstrate learning in practice.

Child↗

PubMed2000

Retroillumination versus reflected-light images in the photographic assessment of posterior capsule opacification.

PURPOSE: To investigate the relative merit of retroillumination and of reflected light slit-lamp-derived photographs in the assessment of the opacification of the posterior lens capsule. METHODS: Retroillumination and slit-lamp-derived reflected-light photographs were taken on 23 consecutive eyes with posterior capsule opacification (PCO) in uncomplicated pseudophakia. Subjective grading was performed on both types of photographs to evaluate the extent and density of posterior capsular opacification. Best-corrected visual acuity (BCVA) before and after YAG laser capsulotomy was used to assess the impact of capsular opacification on visual function. RESULTS: After capsulotomy all patients attained a BCVA > or = 46 letters (> or =20/32) with a mean increase of 25 letters, indicating that PCO was the cause of visual impairment in these patients. The relative capacity of retroillumination and of reflected-light photographs to adequately capture the extent and the severity of posterior capsule opacification varied considerably. Reflected-light images, in addition to frequently producing higher severity scores for the opacity than retroillumination photographs, in 4 of 23 eyes (17.4%) proved to be the only technique able to document the presence of PCO. CONCLUSIONS: Our results indicate that, with respect to retroillumination images, reflected-light photography has an increased ability to adequately capture the presence and the severity of PCO and that the use of only retroillumination images may lead to its underestimation. This may be relevant to clinical studies aiming to evaluate incidence and progression of this condition.

Adult↗

PubMed2000

The reflecting team: an innovative approach for teaching clinical skills to family practice residents.

BACKGROUND AND OBJECTIVES: This paper provides a description and evaluation of the reflecting team approach as a teaching method for family practice residents. We have used the reflecting team approach in our longitudinal behavioral health program for 6 years. Our purpose in using this approach is to 1) teach listening and interviewing skills, 2) teach systems-oriented psychosocial interventions, and 3) provide behavioral health consultations for patients. METHODS: A five-item, self-administered, open-ended questionnaire evaluating the reflecting team approach was administered to a sample of family practice residents. RESULTS: Completed questionnaires were received from 18 of the 22 family practice residents participating in the longitudinal behavioral health program (a response rate of 82%). Responses to the questionnaire items indicated that the residents understood the purpose of the reflecting team approach and felt that they had acquired a variety of clinical skills from the approach, including listening and interviewing skills, positive reframing of patients' problems, how to give positive feedback to promote behavioral change, and increased knowledge of psychosocial assessment procedures and treatment methods. CONCLUSIONS: The residents' responses to the questionnaire items indicated that they perceived the reflecting team approach to be a practical and useful method for learning a variety of clinical skills.

Adult↗

PubMed2002

Reflections on clinical practice by first-year dental students: a qualitative study.

During the first and second year of the dental curriculum, students have little time to process and learn the didactic material in a meaningful way because of the large number of required courses in the curriculum. If an outcome of dental education is to promote critical thinking, however, methods need to be explored to encourage this process in dental students throughout the curriculum. Reflecting on experience is the way learners "make meaning" out of the information they acquire, and "making meaning" is an integral component in the development of critical thinking. The purpose of this pilot study was to explore how reflection on clinical experiences may facilitate the development of critical thinking in first-year dental students as well as assist them in integrating their didactic coursework with clinical care. I used Luborsky's thematic analysis to analyze semi-structured interviews, clinical observations, and written reflection papers from dental students. The major themes identified from the data were: 1) connections between didactic material and the clinical experience, 2) the students' vision of their future role as dentists, and 3) the nature of the dentist-patient interaction. The data further suggest a process of reflective thinking that begins with students' questioning assumptions about their prior experience and knowledge that leads them to look at things in a new way and ultimately to recognize the need to take some action to provide care to the patient. The findings suggest that encouraging students to keep a clinic journal or write reflection papers about their experience may be a way to enhance student learning and is an area that deserves further research.

Adult↗

PubMedDate not supplied

Analyzing the laser-light reflection from human hair fibers. I. Light components underlying the goniophotometric curves and fiber cuticle angles.

The consumer may repeatedly over the day apply intensive grooming procedures to maintain and improve hair appearance. Among these, brushing and combing are responsible for changes if not damage to the hair fiber surface. Beneficial or unfavorable changes to the hair surface may furthermore result from any cosmetic treatment. The analysis of laser-light reflection and scattering of human hair fibers is a direct, quick, and non-destructive method to monitor such surface changes. The application of a laser-based, multichannel goniophotometer is described, by which this analysis is based on the determination of the complete angular distribution of reflected light within a sub-second time interval. Systematic investigations of hairs differing in ethnic origin and color show that the goniophotometric curves can be analyzed by assuming three fractions of reflected light, namely, specularly, diffusely, and internally reflected light. Prominent effects are related to changes of the relative intensities of the different light fractions with hair color. The angular intensity distribution for each of the light fractions is well described by a Gaussian distribution. The angular positions of the peaks and their widths are analyzed. From the systematic shift of the intensity peak for specularly reflected light from its expectation angle, the tilt angle of the cuticle cells on the hair fiber surface is determined. All results are discussed with respect to changes along the hair length and for color differences.

Female↗

PubMed1992

Ageing and wave reflection.

AIM: To determine the effects of wave reflection on the increase in arterial pressure that occurs with age and its association with concomitant changes in both the magnitude and contour of the arterial pressure pulse. RESULTS OF DATA SURVEY: While age-related changes in mean pressure are similar in central and peripheral arteries, changes in pulse pressure and pulse waveform features are different. Because of the specific architectural, geometrical and elastic properties of the arterial vasculature, wave reflection plays an important role in determining peak pressure, the value usually specified as systolic pressure. While the late systolic increase usually determines peak systolic pressure in the central aorta, it is not necessarily related to the peak pressure in the periphery. Peak pressure depends on the timing and intensity of wave reflection, which is a function of the state of the peripheral microvasculature and the elastic properties of the large conduit arteries. Ageing causes changes in both the terminal and central vasculature, so that the intensity of the wave reflection and the transmission properties of arteries affect the arterial pulse to different degrees. Therefore, age-related changes that are observed in the central pressure pulse are different from those observed in the pulse when measured in a limb. Thus the contribution of wave reflection to the determination of peak arterial pressure is not the same at all locations. CONCLUSIONS: These findings have profound implications for therapeutic strategies aimed at altering systolic pressure and for a proper assessment of the alteration in cardiac load that occurs with age or with antihypertensive therapy, when measurements are taken in a limb.

Adult↗

PubMed2004

[Studies on sequential injection spectrophotometric system using a reflective flow cell for process analysis].

A reflective flow cell was developed and coupled to a sequential injection system and optical fiber photometric detection system based on emitting diode light source. A multistrand bifurcated optical fiber was coupled with incident light, detector and flow cell. Optical fibers were used to carry light from the electronics unit to a reflective flow-through cell and back. The liquid flow path through the cell is linear with a large exit aperture such that bubbles are not trapped in the optical path. The optical arrangement is such that the incident light crosses the liquid flow orthogonally and is reflected back to the receiver fiber. This arrangement reduces the reflective index sensitivity by an order of magnitude relative to a conventional flow cell. The cell showed good immunity to refractive index and air bubble effects. The chromogenic reaction of chloride ion with mercury thiocyanate-iron(III) was used as a model reaction to optimize the experiment system and check the optical system. The reflectance of the reaction was monitored with blue emitting diode. The linear range was 0-100 mg x L(-1) Cl-. A detection limit (3sigma) of 1.2 mg x L(-1), precision of 1.5% (n = 11), and a throughput of 30 samples per hour were achieved.

English Abstract↗

PubMed2005

Reflection.

Reflection is thinking about practice, based on traces of recalled facts or data, with a view toward better understanding it. Reflection is prompted by discrepancies between what we observe and what we expect and commonly takes the forms of comparing personal experiences, reviewing events mentally, looking for trends in data, building new prototypes, and managing impressions. Normally, the process involves awareness, reviewing selected traces, resolving tensions, and looking for the greater whole. Practitioners both reflect in practice (specific problem solving) and reflect on practice (drawing general conclusions). The essence of reflection is finding a meaningful way to make tacit knowledge available in explicit form. Often this involves story telling, with its attendant features of plot, emotion, dramatic tension, and the success of the hero.

Awareness↗

PubMed1989

[Light reflection rheography and invasive measurement of venous pressure in the standing exercise test].

The peripheral venous hemodynamics of the lower limbs was simultaneously and repeatedly investigated by means of light-reflection-rheography and peripheral venous pressure measurement with healthy volunteers (total = 40 lower limbs). Two different kinds of exercise were used (knee-bends and tiptoe-stands). The measurements showed highly significant differences (p less than 0.001) between knee-bends and tiptoe-stands not only for all three hemodynamic parameters of non-invasive light-reflection-rheography (maximum reflection difference, refilling time, half-refilling time) but also for all three parameters of the invasive venous pressure measurement (venous pressure difference, refilling time, half-refilling time). There are statistically significant correlations of medium importance (p less than 0.01) between refilling times/half-refilling times of both investigative methods by knee-bends and tiptoe-stands. But there is no significant correlation between light-reflection difference and venous pressure difference. As exercise programme of light-reflection-rheography or invasive peripheral venous pressure measurement the most suitable is the programme in standing position, which represents the maximum hydrostatic load on the insufficient veins and reveals the pathologic condition of venous outflow better than the exercise programme in sitting position.

Adult↗

PubMed1988

A reflectance photometer with a square photodiode array detector for use on multilayer dry-film slides.

This semiautomated prototype reflectance photometer measures reflected light from multilayer dry-film slides. The instrument makes use of a square photodiode array detector, a Hewlett-Packard desktop computer, and a modified mechanical transport mechanism from an Ektachem DT60 analyzer. When 2 microL of serum is placed on a dry-film slide, a colored spot is formed. The slide is automatically transported to an incubation area and then to the photometer area. There the spot is illuminated with dual tungsten lamps, and the reflected light passes through an interference filter, where it is focused on a square photodiode array containing 10,000 individual detectors. The analog signal from each detector is digitized and transmitted to a computer for calculation of the percentage of reflectance. I used a series of algorithms to locate the spot, estimate spot area, correct for minor variations in sample volume, and compute the average reflectance from a central spot area. To evaluate the instrument's performance, I ran parallel glucose determinations in the Beckman Astra; results correlated well. The small sample size along with no dead sample volume makes the system useful for small sample volumes.

Algorithms↗