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PubMed1989

The spectral reflectance of the nerve fiber layer of the macaque retina.

This paper reports the first quantitative measurements of the reflectance spectrum of the nerve fiber layer (NFL) of the retina. An arcuate defect in the NFL of two macaque monkeys was produced by photocoagulating a small spot near the optic disc. Imaging fundus reflectometry at 8 wavelengths was then used to measure the fundal reflectances in the defect and in the intact NFL. The reflectance of the NFL alone was determined by subtracting the reflectance of the bare fundus in the defect from the reflectance of the adjoining fundus with intact NFL. The reflectance data were corrected for the transmission of the ocular media with published values of the density of monkey cornea and lens. Lens absorption was measured from Purkinje images and differed little from the published values. The NFL reflectance can be characterized by a spectrum that has the same shape at all points along an arcuate region of the NFL but decreases in absolute reflectance as the thickness of the NFL decreases. The reflectance changes little between 680 and 560 nm, but rises as lambda-n from 560 to 460 nm, where n = 2.5-3.1. The data reported here begin to provide a quantitative understanding of empirically determined methods for enhancing the visibility of the NFL and have implications for retinal densitometry.

Animals↗

PubMed1981

Evaluation of reflection interference contrast microscope images of living cells.

Reflection contrast microscope methods are generally used for studies of those portions of the cell that are turned towards the glass coverslip, to comprehend the structure of the cytoskeleton and the dynamics of cell movement, as well as formation of cell-glass contacts. In incident illumination only reflected light contributes to picture formation. The intensity of which in the case of observation of unstained cells is small because of small refraction differences. To overcome this problem a reflection contrast system was developed by Leitz according to Ploem [49], in which by using contrast preserving measures the reflection becomes prominent in comparison with the lens reflexes. The emerging pictures are a result of interferences of reflections at glass-cell, cell-culture medium and culture medium-cell interfaces. According to Fresnel's equations the reflected intensity depends on the differences of the particular refractive indices and the thickness of the layers, which determine the phase of interfering beams. In idealized systems of thin films the reflected intensity is a measure for their optical constants. Relative reflection measurements from glass-cell areas is comparison with the known glass-medium reflection, can therefore be revealing as far as refraction index, cell-glass distance or cell thickness are concerned. The estimates by Bereiter-Hahn et al. [15] were made in the assumption of vertical illumination neglecting its actual conical shape: the comparison of two Fresnel functions of cytological relevant measurements show - in accordance with Gingell and Todd [24] - that this is only permitted under certain conditions, depending on the required accuracy of the measurements; an incidence angle of about 30 degrees leads to an error of about 10%, an angle of 50 degrees to more than 50%.

Animals↗

PubMed2007

Analysis of urinary calculi using an infrared microspectroscopic surface reflectance imaging technique.

This investigation highlights the use of infrared microspectroscopy for the morphological analysis of urinary stones. The research presented here has utilized the reflectance mode of an infrared microscope for use in creating chemically specific maps of cross-sectioned renal calculi surfaces, precisely showing the placement of renal stone components in a calculus sample. The method has been applied to renal stones of both single and multiple components consisting primarily of hydroxyapatite, calcium oxalate monohydrate and calcium oxalate dihydrate. Factors discussed include the photometric accuracy of the spectra obtained, a comparison of the surface reflectance method with existing methods such as diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and attenuated total internal reflection (ATR) analysis, and the influence of specular reflectance between polished and unpolished sample spectra. Full spectral maps of cross-sectioned renal stones provided positive localization of components using qualitatively accurate spectra similar in appearance to DRIFTS spectra. Unlike ATR and DRIFTS spectra, surface reflectance spectra lack photometric accuracy and are therefore not quantifiable; at present, however, spectra are suitable for qualitative analysis. It was found that specular reflectance increases minimally with a highly polished stone cross-section surface, though qualitative data is not affected. Surface reflectance imaging of sections of renal stones is useful for determining the identity of stone components while simultaneously providing precise locations of mineral components within the stone using presently available instruments.

Animals↗

PubMed2005

Diffuse reflectance of short-fiber-reinforced composites aligned by an electric field.

OBJECTIVES: This study aims to characterize the translucency of aligned, short-fiber composites by determining the effects of filler particle orientation on the Kubelka-Munk absorption and scattering coefficients. METHODS: Rectangular composite specimens (n = 3) were filled with very short E-glass fibers. The fibers were oriented random, perpendicular, and parallel to the surface normal using an alternating electric field of 0.75 kV/mm. Diffuse reflectances of the composites on white and black backings were acquired with a spectrophotometer. The Kubelka-Munk model was then employed to calculate absorption and scattering coefficients. RESULTS: The ordering of the reflectances on a white backing is neither the same nor the reverse of the reflectances on the black backing. The effects of orientation were different for the absorption and scattering coefficients. Orientation parallel to the average light flux notably decreases the amount of absorption, while perpendicular orientation appreciably increases the amount of scattering. SIGNIFICANCE: Since orientation affects the absorption and scattering coefficients differently, the ordering of the reflectances may be different when the backing is varied. This is because the translucency is composed of two parameters (absorption and scattering) and cannot be adequately summarized with one parameter such as transmittance or reflectance. Therefore, the use of a diffuse reflectance model, such as Kubelka-Munk, is essential to a quantitative understanding of the translucency effects of filler orientation. Understanding how the filler orientation affects diffuse reflectance of composites will yield insight as to how the orientation of enamel rods affects the diffuse reflectance in teeth by analogy.

Absorption↗

PubMed1998

Incorporating the service accomplishments into pre-registration curriculum to enhance reflective practice.

Much emphasis is being placed on the importance of reflective practice as a means to ensure that practitioners are competent in their practice. It is therefore important to ensure that student nurses acquire these reflective skills as part of their development throughout pre-registration curricula. Although reflective practice is seen as a major part of curricula activity, the style in which reflection is advocated takes many different formats. Strategies for developing reflection which focus on outcomes for students can become subjective and fail to place healthcare practice within the context of social structures and values. This paper offers a framework for reflection that promotes an outlook which is both objective and subjective, based on Mezirow's six levels of reflection (as adapted by Powell 1989) and O'Brien's (1987) five service accomplishments. Focus of reflection within the wider context of society and healthcare policy should enable development of a practitioner who is both competent in practice and can analyse and evaluate their practice.

Aged↗

PubMed1998

The role of nurse educators in the development of reflective practitioners: a selective case study of the Australian and UK experience.

The potential to improve patient/client care, stimulate the personal and professional growth of the practitioner and help close the theory practice gap has provoked much discussion in the nursing literature on the benefits of reflection on practice. In order to examine recent developments in this area, a study tour, supported by the Florence Nightingale Foundation, was conducted in Australia and the UK during the spring and summer of 1995. Using an illuminative case study approach, data collected demonstrated that although reflective practice was fully endorsed by the nursing profession in Australia, and there were excellent examples of reflective practice in use, the continued growth of the reflective practice movement appeared to be threatened by the rationalization of both clinical and theoretical education in the universities. Issues around methods of encouraging reflection in students focused on ethical use of journals, the levels of reflection developed and the outcome effectiveness of reflective learning. Although it is recommended that the nursing profession continue to endorse developments in reflective practice in the UK, it is also necessary to encourage both process and outcome evaluations of its effects on the development of the individual nurse and on the ensuing quality of health care delivery.

Australia↗

PubMed2001

Low-reflection-coefficient liquid interfaces for system characterization.

The use of liquid brominated hydrocarbons to form a planar reflecting interface with water is described. Gravity-based planar reflecting surfaces with known reflection coefficients can be used in system characterization for quantitative ultrasonics, and a set of surfaces with a range of reflection coefficients allows calibration of the output power and receiver gain of ultrasonic imaging systems. The substances reported here are immiscible in water and form interfaces with water, resulting in a broad range of acoustic reflection coefficients. Reflection coefficients were measured at temperatures from 18-24 degrees C for "pure" substances and for mixtures of two brominated hydrocarbons. Results show that reflection coefficients are weakly dependent on temperature and that, at a specific temperature, a significant range of arbitrarily small reflection coefficients is available, in the case of the mixtures, by the appropriate choice of weight-percents of the two brominated hydrocarbons.

Hydrocarbons, Brominated↗

PubMed2003

Narrating practice: reflective accounts and the textual construction of reality.

BACKGROUND: Two approaches dominate current thinking in health and welfare: evidence-based practice and reflective practice. Whilst there is debate about the merits of evidence-based practice, reflective practice is generally accepted with critical debate as an important educational tool. Where critique does exist it tends to adopt a Foucauldian approach, focusing on the surveillance and self-regulatory aspects of reflective practice. AIM: This article acknowledges the critical purchase on the concept of reflective practice offered by Foucauldian approaches but argues that microsociological and discourse analytic approaches can further illuminate the subject and thus serve as a complement to them. METHODS: The claims of proponents of reflective practice are explored, in opposition to the technical-rational approach of evidence-based practice. FINDINGS: Reflective practice tends to adopt a naive or romantic realist position and fails to acknowledge the ways in which reflective accounts construct the world of practice. CONCLUSIONS: Microsociological approaches can help us to understand reflective accounts as examples of case-talk, constructed in a narrative form in the same way as case records and presentations.

Communication↗

PubMed2002

Appraising and assessing reflection in students' writing on a structured worksheet.

BACKGROUND: A variety of teaching and learning techniques intended to engage students in reflection are either in use or are being developed in medical and dental education. In line with evidence-based practice in education, research is needed to appraise the utility and effectiveness of these techniques, so that they may be used with confidence. AIM: To assess whether students completing a 'reflective' learning activity based on a structured worksheet really were reflecting. METHOD: A qualitative, multi-method approach was taken. Worksheets completed by students were examined for evidence of reflection by researchers using two sets of criteria for the assessment of reflection derived from the literature, and by peer judges using their own criteria. The opinions of students completing the activity, regarding its acceptability and utility, were elicited by a questionnaire incorporating a 5-point Likert scale. RESULTS: Results from all methods suggest that students completing the activity were reflecting. Students' opinions of the activity were mainly positive. CONCLUSION: The methods employed may be of use to educators wishing to appraise reflective learning activities or, possibly, to assess student reflection.

Clinical Competence↗

PubMed2004

Latency and the capacity to reflect on mental states.

The development of the capacity to reflect on mental states has its origins in the mother's function of accepting the infant's projections of unbearable states of mind and re-presenting them in a more tolerable form. During the oedipal period, the continued availability of a parent who can take in the child's mental states and represent them from a different perspective results in the emergence within the child of a reflective mode of mental functioning. This mental capacity allows the child entering latency to begin to be able to recognize that her experience is but one perspective among many. Reflection on mental states takes place within an intermediate area of experience that belongs neither to the inner world nor to external reality, but partakes of both. In latency, the capacity to reflect on mental states remains a vulnerable capacity that is dependent on the reflective function of a parent at times of crisis. When a parent who can contain and transform the child's experience is not available, the child's potential space for reflection can collapse, leaving the child unable to differentiate inner from outer reality. The mother's relationship to a loved object other than the child is necessary for her continuing ability to support the child's reflective function. The child's awareness of a parental relationship from which she is excluded is also essential to the child's internalization of the capacity to reflect on mental states because it creates a vantage point from which the child can imagine herself being observed from the outside. These points are illustrated with material from a first psychotherapy session with a latency age boy.

Ego↗

PubMed2003

Reflected appraisals and perceived importance of significant others' appraisals as predictors of college athletes' self-perceptions of competence.

This study examined the reflected appraisal process with college athletes (N = 325). Specifically, the study tested (a) the relative influence of the reflected appraisals of mothers, fathers, coaches, and teammates (i.e., how athletes perceive these others view their ability) on athletes' self-perceptions of competence, and (b) whether the importance placed on these significant others as sources of competence information moderated the relationship. Based on a factor analysis, composite variables were formed representing the reflected appraisals of the athletes' parents (i.e., father, mother) and the reflected appraisals of sport-others (i.e., coach, teammates). Regression analyses revealed that the reflected appraisals of parents (beta = .21) and sport-others (beta = .55) predicted self-perceptions of competence (p < .05, R2 = .45). Follow-up analyses determined that the reflected appraisal of sport-others was a significantly stronger predictor. Hierarchical regression analyses revealed that the interaction of reflected appraisals and the importance of significant others did not significantly add to the prediction of self-perceptions of competence (p > .05, deltaR2 = .01) beyond the independent effects of these constructs. Results are discussed in terms of the reflected appraisal process and the influence of significant others on athletes' self-perceptions.

Adolescent↗

PubMed2005

Maternal reflective functioning, attachment, and the transmission gap: a preliminary study.

The notion that maternal reflective functioning, namely the mother's capacity to hold her baby and his mental states in mind, plays a vital role in the intergenerational transmission of attachment is investigated (Fonagy, Gergely, Jurist, & Target, 2002; Fonagy et al., 1995; Slade, this volume). A parent's capacity to understand the nature and function of her own as well as her child's mental states, thus allowing her to create both a physical and psychological experience of comfort and safety for her child, is proposed. In this study of 40 mothers and their babies, maternal reflective functioning is measured using the Parent Development Interview (PDI; Aber, Slade, Berger, Bresgi, & Kaplan, 1985), and scored for reflective functioning using an addendum to Fonagy, Target, Steele, & Steele's (1998) reflective functioning scoring manual (Slade, Bernbach, Grienenberger, Levy, & Locker, 2004). The relations between maternal reflective functioning and both adult (measured in pregnancy) and infant attachment (measured at 14 months) are examined. The findings indicate that relations between adult attachment and parental reflective functioning are significant, as are relations between parental reflective functioning and infant attachment. A preliminary mediation analysis suggests that parental reflective functioning plays a crucial role in the intergenerational transmission of attachment.

Adult↗

PubMed2005

Using reflection activities to enhance teaching about end-of-life care.

BACKGROUND: While reflection on experiences and attitudes related to death can be an important component of learning to care for the dying, opportunities within the medical school curriculum to promote learner reflection are often limited. OBJECTIVE: To describe implementation and evaluation of activities in an end-of-life curriculum to promote self-reflection and student concerns and thoughts revealed through reflection exercises. DESIGN: Within a lecture-based course on end-of-life care, second-year medical students participated in four activities to promote self-reflection, including: (1) visualizing their own deaths; (2) documenting their experiences with death; (3) writing essays reacting to course content; and (4) participating in physician-led small group sessions. MEASUREMENTS: Student reaction essays and small group evaluations. RESULTS: Qualitative analysis of student reaction essays (2002-2004; total, n = 522) revealed nine major themes in student concerns and thoughts related to caring for the dying. These included: (1) expressing emotions; (2) personal grief and emotional detachment; (3) communicating effectively; (4) spending enough time; (5) feeling ill-prepared to deal with death; (6) losing a loved one; (7) shifting emphasis from curing to caring; (8) listening to patients and respecting their decisions and (9) previous negative end-of-life experiences. Analysis of essays and evaluations assessed the impact of the various reflection activities and demonstrated that these activities allowed students to critically examine and discuss their experiences and concerns regarding providing end-of-life care. CONCLUSIONS: A variety of activities can be incorporated successfully into a largely didactic curriculum to promote student reflection on their attitudes and concerns related to end-of-life care, thereby laying an important foundation for their future practice in caring for the dying. In addition, analysis of student reflection essays can serve as an important curriculum evaluation tool.

Curriculum↗

PubMed1976

Reflection in the systemic arterial system: effects of aortic and carotid occlusion.

Experiments were performed in seven closed-chest anaesthetized male dogs to determine the role of pulse wave reflection in the pattern of flow and pressure in the ascending aorta. Ten days after implantation of an electromagnetic flow transducer around the ascending aorta a balloon catheter was placed in the descending aorta via the femoral arteries. At the same time a tip manometer was introduced into the ascending aorta. Aortic occlusions at three different sites caused pressure pulses with secondary systolic rises and flow pulses with biphasic deceleration. Secondary rises occurred 45 +/- 9.0 ms after the initial pressure rise for high aortic occlusion; this time was 75 +/- 8.5 ms for occlusion at the level of the diaphragm and 114 +/- 16.5 ms for occlusion near the level of the renal arteries. These times approximate the times in which the pulse travels from the tip manometer to the inflated balloons and back. Forward and reflected pressure and flow waves were calculated from reflection coefficients. Aortic occlusion caused larger reflected waves and the recorded wave forms were caused by the summation of forward and backward waves, the latter contributing the secondary pressure rise and the increased flow deceleration. Occlusion of both carotid arteries showed no specific reflection site but reflected waves were larger. This increased reflection can probably be explained as the result of greater total reflection from distributed sites under increased peripheral resistance.

Animals↗

PubMed2006

Systemic arterial pressure wave reflections during acute hemorrhage.

OBJECTIVE: To determine the effects of hemorrhage on wave-reflection-induced systolic pressure augmentation in the aorta. DESIGN: Randomized, controlled laboratory experiment. SETTING: University research laboratory. SUBJECTS: Twenty-five anesthetized pigs randomized to surgical controls (n = 7), hemorrhage (n = 9, H), and hemorrhage with reinfusion (n = 9, HR). INTERVENTIONS: Hemorrhage of 1 mL/kg/min over 20 mins followed by observation (H) or reinfusion (HR) of shed blood. MEASUREMENTS AND MAIN RESULTS: High-fidelity systemic arterial pressure waveforms, from ascending aorta to femoral artery, were transduced and archived digitally using intravascular semiconductor catheter-tipped pressure transducers. Wave-reflection-induced systolic pressure augmentation was determined using the augmentation index in the ascending aorta (AIaa) and distal descending aorta (AIda). Pulse wave velocity, wave travel times, and lumped pressure wave reflection sites were also calculated. AI values were positive at baseline with greater decreases in AIda compared with AIaa observed following hemorrhage, with negative values achieved for AIda alone. AI returned to control values following reinfusion. Lumped reflection site positions and pressure contour maps suggested that a single lumped reflection site (lower abdomen/pelvis) at baseline was replaced by two discrete sites (upper abdomen and pelvis) following hemorrhage, which only recovered following reinfusion. Hemorrhage was associated with hemodynamic conditions that favored late return of wave reflection from the trunk and with the absence of significant changes in systemic vascular resistance. CONCLUSIONS: Hemorrhage-induced early return of pressure wave reflection from the abdominal vasculature is associated with systolic pressure augmentation in the ascending aorta and has the potential to worsen afterload conditions and decrease coronary artery perfusion and cardiac performance. Hemorrhage-induced splanchnic vasoconstriction causing pressure wave reflection may explain these loading conditions in the ascending aorta, and systolic pressure augmentation may be a more useful guide to left ventricular afterload than systemic vascular resistance.

Analysis of Variance↗

PubMed2005

Ultraviolet reflecting photonic microstructures in the King Penguin beak.

King and emperor penguins (Aptenodytes patagonicus and Aptenodytes forsteri) are the only species of marine birds so far known to reflect ultraviolet (UV) light from their beaks. Unlike humans, most birds perceive UV light and several species communicate using the near UV spectrum. Indeed, UV reflectance in addition to the colour of songbird feathers has been recognized as an important signal when choosing a mate. The king penguin is endowed with several highly coloured ornaments, notably its beak horn and breast and auricular plumage, but only its beak reflects UV, a property considered to influence its sexual attraction. Because no avian UV-reflecting pigments have yet been identified, the origin of such reflections is probably structural. In an attempt to identify the structures that give rise to UV reflectance, we combined reflectance spectrophotometry and morphological analysis by both light and electron microscopy, after experimental removal of surface layers of the beak horn. Here, we characterize for the first time a multilayer reflector photonic microstructure that produces the UV reflections in the king penguin beak.

Animal Communication↗

PubMed2002

Metal strip reflectivity and NSPUDT orientations in langanite, langasite, and gallium phosphate.

New materials of the trigonal 32 class have received much attention recently, due to their quartz-like temperature behavior and the promise of higher electromechanical coupling coefficients. The magnitude and phase of the reflection coefficient of the metal strips that form the SAW transducers and reflector structures is a critical parameter that allows proper device designs and optimal material surface orientation. This paper describes an investigation of the magnitude and phase of the SAW metal strip reflectivity in some new materials and along new orientations. The materials are langanite, langasite, and gallium phosphate. The results are presented as contour plots of the magnitude and phase of the reflection coefficient. In addition, the phase velocity, temperature coefficient of delay, electromechanical coupling coefficient, and power flow angle are given, thus allowing proper orientation selection for SAW device designs. The results presented highlight the reflection coefficient calculations in the selection of natural single-phase unidirectional transducer orientations (NSPUDT) for these new materials. As a result of the present work, reflection coefficient magnitudes five times larger than those of the well-known quartz NSPUDT orientation (Euler angles: 0 degrees 132.75 degrees 25 degrees) can be obtained with the new materials, for orientations where the optimum NSPUDT reflection coefficient phase criterion is met. The new materials discussed here provide an opportunity to design shorter- and higher-bandwidth devices due to: the increased electromechanical coupling coefficient; the higher reflection coefficient; and the lower phase velocities; while maintaining the excellent temperature insensitivity characteristic of quartz. The orientation regions suggested in this paper for the new materials are thus very promising for low-loss, high-performance consumer and communications SAW designs, such as NSPUDT filters, resonator-based filters, and other devices that can benefit from a high metal strip reflectivity.

Journal Article↗

PubMed2004

The structure of reflective practice in medicine.

BACKGROUND: The capability to reflect consciously upon one's professional practice is generally considered important for the development of expertise and, hence, for education. However, to our knowledge no empirical research has been conducted to date into the nature of reflective practice in medicine. PURPOSE: To study the structure of reflective practice in medicine. METHODS: A questionnaire based on the literature was developed and administered to a group of primary care doctors. The data were subjected to confirmatory factor analysis using structural equations modelling. RESULTS: A 5-factor model of reflective practice emerged. It consisted of the following factors: deliberate induction; deliberate deduction; testing and synthesising; openness for reflection, and meta-reasoning. The model fitted the data sufficiently. CONCLUSION: A multidimensional structure of reflective practice in medicine was brought to light by the study. Its components in terms of reasoning processes, behaviours and attitudes were identified and measured among doctors. Once conceptualised and measured, reflective practice can be studied to gain a better understanding of its relation to expertise development in medicine. In addition, training students to apply reflective practices may become a goal in medical education.

Attitude of Health Personnel↗