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PubMed1994

Measurement of acoustic impedance and reflectance in the human ear canal.

The pressure reflectance R (omega) is the transfer function which may be defined for a linear one-port network by the ratio of the reflected complex pressure divided by the incident complex pressure. The reflectance is a function that is closely related to the impedance of the 1-port. The energy reflectance R (omega) is defined as magnitude of [R]2. It represents the ratio of reflected to incident energy. In the human ear canal the energy reflectance is important because it is a measure of the inefficiency of the middle ear and cochlea, and because of the insight provided by its simple frequency domain interpretation. One may characterize the ear canal impedance by use of the pressure reflectance and its magnitude, sidestepping the difficult problems of (a) the unknown canal length from the measurement point to the eardrum, (b) the complicated geometry of the drum, and (c) the cross-sectional area changes in the canal as a function of distance. Reported here are acoustic impedance measurements, looking into the ear canal, measured on ten young adults with normal hearing (ages 18-24). The measurement point in the canal was approximately 0.85 cm from the entrance of the canal. From these measurements, the pressure reflectance in the canal is computed and impedance and reflectance measurements from 0.1 to 15.0 kHz are compared among ears. The average reflectance and the standard deviation of the reflectance for the ten subjects have been determined. The impedance and reflectance of two common ear simulators, the Brüel & Kjaer 4157 and the Industrial Research Products DB-100 (Zwislocki) coupler are also measured and compared to the average human measurements. All measurements are made using controls that assure a uniform accuracy in the acoustic calibration across subjects. This is done by the use of two standard acoustic resistors whose impedances are known. From the experimental results, it is concluded that there is significant subject variability in the magnitude of the reflectance for the ten ear canals. This variability is believed to be due to cochlear and middle ear impedance differences. An attempt was made at modeling the reflectance but, as discussed in the paper, several problems presently stand in the way of these models. Such models would be useful for acoustic virtual-reality systems and for active noise control earphones.

Acoustic Impedance Tests↗
PubMed2001

Reflective properties of iridophores and fluorescent 'eyespots' in the loliginid squid Alloteuthis subulata and Loligo vulgaris.

Observations were made of the reflective properties of the iridophore stripes of the squid Alloteuthis subulata and Loligo vulgaris, and the likely functions of these stripes are considered in terms of concealment and signalling. In both species, the mantle muscle is almost transparent. Stripes of iridophores run along the length of each side of the mantle, some of which, when viewed at normal incidence in white light, reflect red, others green or blue. When viewed obliquely, the wavebands best reflected move towards the blue/ultraviolet end of the spectrum and their reflections are almost 100% polarised. These are properties of quarter-wavelength stacks of chitin and cytoplasm, predicted in theoretical analyses made by Sir A. F. Huxley and Professor M. F. Land. The reflecting surfaces of the individual iridophores are almost flat and, in a given stripe, these surfaces are within a few degrees of being parallel. Both species of squid have conspicuous, brightly coloured reflectors above their eyes. These 'eyespots' have iridescent layers similar to those found on the mantle but are overlaid by a green fluorescent layer that does not change colour or become polarised as it is viewed more obliquely. In the sea, all reflections from the iridophore stripes will be largely confined to the blue-green parts of the spectrum and all reflections in other wavebands, such as those in the red and near ultraviolet, will be weak. The functions of the iridophores reflecting red at normal incidence must be sought in their reflections of blue-green at oblique angles of incidence. These squid rely for their camouflage mainly on their transparency, and the ventral iridophores and the red, green and blue reflective stripes must be used mainly for signalling. The reflectivities of some of these stripes are relatively low, allowing a large fraction of the incident light to be transmitted into the mantle cavity. Despite their low reflectivities, the stripes are very conspicuous when viewed from some limited directions because they reflect light from directions for which the radiances are much higher than those of the backgrounds against which they are viewed. The reflective patterns seen, for example, by neighbouring squid when schooling depend on the orientation of the squid in the external light field and the position of the squid relative to these neighbours.

Animal Communication↗
PubMed2001

Low compliance rather than high reflection of arterial system decreases stroke volume in arteriosclerosis: a simulation.

Although various investigators have suggested that the left ventricles of aged subjects suffer from high-frequency reflection, arterial reflection is larger in the low-frequency range because of a larger impedance mismatch. It has not been quantified whether high-frequency reflection rather than low-frequency reflection has larger deleterious effects on stroke volume. We used a computer simulation method to evaluate how increases in high- and low-frequency arterial reflections associated with age-related arterial sclerosis affect left ventricular (LV) pump function. Low-frequency reflections derive principally from the total arterial compliance, and high-frequency reflections result from impedance fluctuations in the high-frequency range. We numerically coupled a time-varying elastance LV model with a variety of arterial impedances to quantitatively evaluate the effects of low- and high-frequency reflections on LV pump performance. When we simultaneously increased low- and high-frequency reflections to levels of sclerotic impedance (type A in Murgo et al., Circulation 62: 105-116, 1980), stroke volume decreased by 4.4%. Further increases of the reflections up to 8 times of the type A impedance lowered stroke volume by 15.9%. This trend was clearly seen with selective increases in low-frequency reflections (3.5 and 20.2% decrease in stroke volume, respectively), but not with those in high-frequency reflections (1.0% decrease and 0.9% increase in stroke volume, respectively). Thus we conclude that the detrimental effect of increases in arterial reflections associated with arterial sclerosis on stroke volume is mild and mainly attributable to decreased compliance rather than to increased high-frequency reflections.

Arteriosclerosis↗
PubMed2001

Developing critical reflection for professional practice through problem-based learning.

AIMS: To explore the influence of current learning traditions in nursing on the development of reflection and critical reflection as professional practice skills and to offer suggestions for nursing education that will specifically facilitate the development of critical reflection. ORGANIZATIONAL CONSTRUCTS: Mezirow's transformative learning theory, Barrows conceptualization of problem-based learning (PBL). METHODS: Integrative literature review of published literature related to nursing, health science education and professional education from 1983-2000. FINDINGS: Professional education scholars concur that specialized knowledge is clearly essential for professional practice, however, they also suggest that self-consciousness (reflection) and continual self-critique (critical reflection) are crucial to continued competence. While strategies to facilitate reflection have been outlined in the literature, specific strategies to facilitate the development of critical reflection and implications for nursing education are much less clear. Advocates of reflective and critically reflective practice suggest that the development of these abilities should be inextricably linked to professional development and can be developed through active repeated guided practice. In health care, PBL based on constructivism, has been identified as one way to facilitate the development of these skills. CONCLUSIONS: Nursing learners exposed to PBL develop the ability to be reflective and critically reflective in their learning and acquire the knowledge and skill within the discipline of nursing by encountering key professional practice situations as the stimulus and focus of their classroom learning. The learners' ability to be both reflective and critically reflective in their learning is developed by critical questioning of the faculty tutor during situational analysis, learning need determination, application of knowledge, critique of resources and personal problem-solving processes, and summarization of what was learned.

Education, Nursing↗
PubMedDate not supplied

Reflection: possible strategies to improve its use by qualified staff.

Reflection is now a prerequisite for all nurses, midwives and health visitors (UKCC, 2001). It is the method endorsed by the UKCC to promote the development of informed, knowledgeable and safe practice, and qualified practitioners are required to maintain a personal professional profile containing evidence of reflection on practice. The aim of this article is to examine why qualified practitioners may be reluctant to reflect formally, to speculate on the possible barriers to reflection, and to suggest how reflection can be promoted positively as an integral part of nursing practice. The article begins with an examination of definitions of reflection, reflective theory and the purpose of reflection, and continues by questioning whether the concept of reflection has been embraced as eagerly by nurses at 'grass roots' as it has by academia, the nursing press and the UKCC. It is suggested that several barriers to effective reflection may create a division between practitioners and the professional hierarchy regarding the conceived common practice of reflection, and strategies are proposed that may help to overcome these barriers. The discussion concludes by prioritizing the need for a clear definition and concept analysis of reflection, supported by long-term investment into research that explores the effect of reflection on clinical practice and patient care.

Awareness↗
PubMed1988

Developing red cell flow orientation shown by changes in blood reflectivity.

The rate of onset of erythrocyte flow orientation at normal concentration has not previously been established. Reflectivity of blood and resuspended non-aggregated red cells at normal (41%) and elevated (60%) hematocrit has been used to examine this process. Video recordings were made before, during, and after shearing by bob motion in a cylinder-in-cylinder viscometer at shear rates ranging from 4 to 100 inverse seconds. Unaggregated erythrocytes in PBS, already more reflective than blood before shearing, became even more reflective during shearing even at the lowest shear rate studied. The time required for the increased reflectivity to stabilize was observed to be inversely proportional to shear rate for both blood and resuspended red cells. Reflection became constant after a total shear strain (bob shear rate x time) from 4 to 10 at all shear rates studied. Onset of increased reflection expressed in total shear strain units (an index of overall bob movement) was independent of shear rate in the absence of aggregation. When red cells were studied in native plasma, reflectivity increased as much as 30% during shearing, but always remained below unaggregated red cell reflectivity for the same hematocrit and shear rate. Greater reflectivity of unaggregated red cells persisted after cessation of shearing, while blood's reflectivity dropped progressively over several seconds to its pre-shearing value. The geometry chosen for study and insensitivity to light source composition indicate that specular reflection by red cells near the cup's inner surface is responsible for the increased light return during flow. Maximal rate of rise in reflectivity at all shear rates studied was observed to coincide with blood's previously reported transient shear stress overshoot and to correspond with an overall bob motion that would rotate suspended particles approximately 45 degrees. The close relation of both reflectivity increase and shear stress overshoot to such modest overall bob movement indicates that an efficient flow-mediated rotation of either individual or aggregated erythrocytes from initially random positions toward an orientation in the shear plane characterizes flow onset.

Erythrocytes↗
PubMedDate not supplied

Optical properties of hair--detailed examination of specular reflection patterns in various hair types.

Details of the specular reflection of curved hair tresses, resulting from illumination with a collimated incident light source, were examined both qualitatively and quantitatively using high-resolution photography and image analysis. The reflections were found to consist of a multitude of light dots aligned with the fibers and typically separated by a distance of 81-145 microm. The contrast between the dots (specular reflection) and the darker regions (diffuse reflection) of the entire reflection band was found to increase with increasing pigmentation of hair. Highly pigmented Oriental hair provided more contrast within the specular reflection band than unpigmented natural white hair. A quantitative description of the light reflection patterns within the specular reflection band included two-dimensional distribution of luminosity, histograms of the frequency of appearance for peak maxima and minima in luminosity distribution plots, and histograms of absolute maxima and minima of luminosity along the length of the fibers. Specular reflection from African hair, which consists of many curls that provide multiple and randomly distributed reflection centers, have also been investigated. Using microscopy software, Image Tool 2.0, and a method termed image threshold, the number of reflection sites and their shapes could be quantified. For example, treatment of African hair with synthetic sebum was shown to significantly affect the reflection patterns, resulting in a decrease in the overall hair luster. Comparison of reflection patterns from Caucasian frizzy, very curly, and curly hair is also discussed.

Hair↗
PubMed2006

Implementing reflection: insights from pre-registration mental health students.

Reflection and reflective practice continues to be contentious issues in nursing. The focus of this article is the use of reflection by pre-registration mental health students. The broad aim of this preliminary study was to discover student mental health nurses' perceptions of reflection as a learning strategy during clinical placement. Using a constructivist grounded theory methodology [Charmaz, K., 2000. Grounded theory: Objectivist and Constructivist Methods. In: Denzin, N., Lincoln, Y. (Eds.), Handbook of Qualitative Research, second ed. Sage, Thousand Oaks, California], five students were interviewed individually in their clinical placements. Data analysis revealed three major categories: understanding the process of reflection, using reflection in clinical practice, and needing support and guidance. Findings indicated that students were primarily using reflection-on-action, but to varying extents. Overall, students felt that reflection facilitated their learning. Factors were discovered that both helped and hindered students' use of reflection. These included level of preparation to reflect, a limited culture of reflection and the level of support from preceptors, clinical staff, clinical placement co-ordinators, and lecturers. In conclusion, it appears that a collaborative approach between students, Health Service Providers and institutes of nursing is vital for the successful development and implementation of reflective learning strategies in clinical placement. Suggestions are made as to how a collaborative approach may be developed to enhance this process.

Attitude of Health Personnel↗
PubMed1992

Light reflection rheography as a noninvasive screening test for deep venous thrombosis.

STUDY OBJECTIVE: To determine if light reflection rheography is a useful screening tool for the diagnosis of proximal leg deep venous thrombosis. DESIGN: Light reflection rheography was compared with duplex ultrasonography and/or contrast venography on emergency patients being evaluated for proximal leg deep venous thrombosis. SETTING: University hospital emergency department. TYPE OF PARTICIPANTS: Seventy-five ED patients being evaluated for acute leg deep venous thrombosis. INTERVENTIONS: Seventy-five patients being evaluated for clinically suspected deep venous thrombosis had light reflection rheography performed on the involved extremity immediately before duplex ultrasonography and/or contrast venography. Duplex ultrasonography and/or contrast venography was the definitive diagnostic test. MEASUREMENTS AND RESULTS: Seventy-five patients had light reflection rheography performed, 72 had duplex ultrasonography, 19 had contrast venography, three had contrast venography alone, and 16 had both duplex ultrasonography and contrast venography. A comparison of light reflection rheography with duplex ultrasonography and/or contrast venography reveals that 39 light reflection rheography examinations were true-negative, 17 were true-positive, one was false-negative, and 18 were false-positive. The sensitivity of light reflection rheography for the detection of proximal leg deep venous thrombosis is 94.4% (95% confidence interval [CI], 72.7-99.9%), the negative-predictive value is 97.5% (95% CI, 86.8-99.9%), the specificity is 68.4% (95% CI, 54.8-80.1%), and the positive-predictive value is 48.6% (95% CI, 31.4-66%). CONCLUSION: Light reflection rheography proved to be an excellent screening tool for emergency patients with the clinical suspicion for an acute proximal leg deep venous thrombosis. A normal light reflection rheography examination was 97.5% accurate as a negative predictor. That is, a normal light reflection rheography excluded the diagnosis of proximal leg deep venous thrombosis when compared with duplex ultrasonography and/or contrast venography when the duplex ultrasonography and/or contrast venography showed no evidence of proximal leg deep venous thrombosis. An abnormal light reflection rheography does not equate to an acute leg deep venous thrombosis as the specificity was only 68.4%. An abnormal light reflection rheography mandates further diagnostic studies such as duplex ultrasonography and/or contrast venography to confirm a diagnosis of proximal leg deep venous thrombosis.

Adult↗
PubMed1995

Reflection-on-practice: enhancing student learning.

The writing of a reflective diary is viewed as an effective tool for promoting reflection and learning in students, and for self-assessment and evaluation of a clinical learning experience. This work is a study of 30 undergraduate nurses and their use of reflective diaries during a period of community health care practice. The theoretical basis of the study is based on Schön's work on reflection-in-action. The research tool, developed for the study of nursing practice by Powell, is based on Mezirow's levels of reflectivity. The findings are that, in the sample used, students do reflect on their practice according to Mezirow's levels of reflectivity, but that the highest number of reflections occur at the lower levels of reflectivity (94% of the total number of scores). However, although only 6% of the total number of scores were found at the higher levels of reflectivity, some 22 of the samples of 30 students did attain conceptual and theoretical reflectivity, the highest levels of reflectivity.

Cognition↗
PubMed1989

Effects of dream reflection on waking affect: awareness of feelings, rorschach movement, and facial EMG.

The clinical and research literature suggests that waking dream reflection increases awareness of feelings. To examine this possibility, 16 male and 16 female participants spent a single night in the sleep laboratory while rapid eye movement (REM) sleep physiology and facial electromyogram (EMG) were monitored. Participants in the dream imagery condition were awakened from REM sleep and asked to reflect on their dreams. Participants in the fantasy imagery condition were awakened from REM sleep and asked to reflect on guided fantasies modeled on dream narratives. Participants were asked to reflect either on the affective connotations of their imagery or on the cognitive aspects of their imagery. Unexpectedly, self-reported awareness of feelings was less common during either affective or cognitive reflection on dreams than during such reflection on fantasies, especially for females. Also, kinesthetic sensitivity, as indicated by Rorschach movement responses, was less after dream reflection than after reflection on fantasy imagery, again especially for females. In contrast, facial EMG activity was greater during dream reflection than during fantasy reflection. Since facial EMG during REM sleep and during dream reflection was correlated with self-reported orienting within dream imagery, these results are understandable as evidence for the "carry-over" of REM orienting activity during dream reflection, resulting in reduced affective/kinesthetic sensitivity and reduced awareness of feelings.

Adolescent↗
PubMed2001

Wideband reflectance tympanometry in chinchillas and human.

Wideband reflectance tympanometry was performed on twelve chinchillas ears. The complex input impedance of the middle ear, multifrequency admittance tympanograms, reflectance patterns (reflectance versus frequency), and reflectance tympanograms (reflectance versus ear-canal air pressure) were analyzed and compared to human data. The complex impedance of the chinchilla ear has a lower stiffness reactance at low frequencies, a higher mass reactance at high frequencies, and a lower resistance compared to the human. Multifrequency admittance tympanograms from chinchillas follow the same sequence of patterns as humans for low frequencies (<2 kHz). At higher frequencies tympanograms from both species are poorly organized and do not follow a consistent sequence of patterns. Reflectance patterns of chinchillas and humans are different. However, both species show high reflectance at low frequencies, regions of lower reflectance in mid-frequencies (2-6 kHz), and high reflectance at high frequencies (>8 kHz). Reflectance tympanograms for the two species show a single, centrally located minimum at low frequencies (<2 kHz) and are substantially different at higher frequencies. Results are shown for two animals that underwent eustachian tube obstruction. Reflectance patterns obtained with different ear-canal air pressures are substantially different. Reflectance results at any single ear-canal pressure (including ambient pressure) do not completely characterize the effects of middle-ear pathology.

Acoustic Impedance Tests↗
PubMed1985

Regional wave travel and reflections along the human aorta: a study with six simultaneous micromanometric pressures.

The human aorta and its terminal branches were investigated in normal subjects during elective cardiac catheterization to evaluate regional wave travel and arterial wave reflections. A specially designed catheter with six micromanometers equally spaced at 10 cm intervals was positioned with the tip sensor in the distal external iliac artery and the proximal sensor in the aortic arch. Simultaneous pressures were obtained and analyzed for foot-to-foot wave velocity, and Fourier analysis was used to derive apparent phase velocity. These quantities were assessed during control (n = 9), during Valsalva (n = 8) and Müller (n = 4) maneuvers, and during femoral artery occlusion by bilateral manual compression (n = 8). During control, regional cross-sectional areas, determined from aortography, and regional foot-to-foot pulse wave velocities were used to calculate the local reflection coefficient in the proximal descending aorta (gamma = 0.05), at the junction of the renal arteries (gamma = 0.43), and at the terminal aortic bifurcation (gamma = 0.13). To test the hypothesis that significant reflections originate in the aorta, at the level of the renal arteries, aortograms were used to design a latex tube model with geometric properties similar to the descending aorta. Velocities and reflection characteristics in the model and in vivo were compared. Inspection of thoracic aortic pressures under control conditions revealed a reflected wave originating from the region of the aorta at the level of the renal arterial branches while abdominal pressures exhibited reflection from a site peripheral to the terminal aortic bifurcation. In the low frequency range, apparent phase velocity was found to be higher proximal to the renal arteries as compared with at the distal sites. In addition, the minimum value occurred at a higher frequency in the lower thoracic aorta than at more distal sites. The effects of reflection on apparent wave velocity in the tube model were consistent with data obtained in vivo. The Valsalva maneuver diminished the reflection from the aortic region of the renal arteries, thus allowing the distal reflected wave to become more evident on the thoracic pressure waveforms. Bilateral femoral artery occlusion usually enhanced the distal reflection and the Müller maneuver usually resulted in small increases in reflections. In conclusion, the geometric and elastic nonuniformity of the aorta results in two major sites of arterial wave reflection that influence the aortic pressure waveforms in man.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed2002

Reflection: possible strategies to improve its use by qualified staff.

Reflection is now a prerequisite for all nurses, midwives and health visitors (UKCC, 2001). It is the method endorsed by the UKCC to promote the development of informed, knowledgeable and safe practice, and qualified practitioners are required to maintain a personal professional profile containing evidence of reflection on practice. The aim of this article is to examine why qualified practitioners may be reluctant to reflect formally, to speculate on the possible barriers to refection, and to suggest how reflection can be promoted positively as an integral part of nursing practice. The article begins with an examination of definitions of reflection, reflective theory and the purpose of reflection, and continues by questioning whether the concept of reflection has been embraced as eagerly by nurses at 'grass roots' as it has by academia, the nursing press and the UKCC. It is suggested that several barriers to effective reflection may create a division between practitioners and the professional hierarchy regarding the conceived common practice of reflection, and strategies are proposed that may help to overcome these barriers. The discussion concludes by prioritizing the need for a clear definition and concept analysis of reflection, supported by long-term investment into research that explores the effect of reflection on clinical practice and patient care.

Journal Article↗
PubMed2005

Correlates of reflective practice in medicine.

BACKGROUND: The ability of physicians to critically reflect on their professional practice has been increasingly valued. Previous research brought to light the multidimensional structure of reflective practice in medicine. It comprises at least five sets of behaviours in response to complex medical problems encountered in professional practice. Factors associated to reflective practice among physicians have, as far as we know, not yet been explored by empirical study. PURPOSE: To study factors correlated to reflective practice among physicians. METHODS: A questionnaire exploring characteristics of professional practice and educational experiences was administered to primary health care physicians. Measurements were related to scores on a reflective practice measuring instrument developed previously. Associations between variables were examined by statistical analysis with tests of correlation and analysis of variance. RESULTS: Reflective practice is negatively correlated to physician's age and number of years of clinical practice. Working mainly in hospitals and attendance to medical residency programmes in some specialties apparently have a positive effect on reflective practice. CONCLUSION: Reflective practice tends to decrease with experience. Findings are consistent with the literature on medical expertise that shows a decline of analytical reasoning in proportion to the increase in experience. Some specialty programmes seems to enhance concerns with the scientific basis to professional practice, thereby favouring reflective approaches. Local features of primary health care settings probably explain their negative effect on reflective practice. Strategies to develop reflective practice among physicians should be explored by further research.

Adult↗
PubMed1996

Reflective practice in the accident and emergency setting.

The object of this paper is critically to analyse the issue of reflective practice within the writer's own professional arena. The writer is a senior nurse within an Accident and Emergency (A & E) department. It has long been recognised that a gap exists between theory and practice in nursing. There has been much discussion in the nursing literature about the development of the reflective practitioner and how reflection in practice can assist in closing the theory-practice gap. Nurses have always experienced great difficulty in identifying a theory of practice. Jarvis (1992) states that reflective medicine is a frequently used but infrequently defined concept in nursing at the present time. For both qualified nurses and students alike, reflection can be utilised as a learning process to help them expand and develop their clinical knowledge and skills to directly benefit client care (Dewing 1990). Schon (1987) has identified reflection as a process of knowledge acquisition originating in practice and best suited to solving complex practice based problems. Reflection is an active process of exploration and discovery which often leads to unexpected outcomes (Boud et al 1985). Reflection that occurs in the process of an experience is referred to as reflection-in-action (Schon 1987). Nurses have the ability to think about their actions while they are carrying them out and change the actions should the professional's assessment of the situation change (Schon 1983). Reflection can lead to new understanding and appreciation which can be put to use in future experiences (Dewing 1990). This paper will commence with a brief explanation of how nurse education is developing reflection and experience to assist the student nurse to close the theory-practice gap.

Clinical Competence↗
PubMed2001

New vegetation indices for remote measurement of chlorophylls based on leaf directional reflectance spectra.

Directional reflectance (R) spectra from 380 to 780 nm for nadir illuminated leaves of four different plants (croton, Codiaeum variegatum; spotted eleagnus, Eleagnus pungens Maculata; Japanese pittosporum, Pittosporum tobira and Benjamin fig, Ficus benjamina Starlight) were acquired at a viewing angle of 30 degrees from the nadir direction. Chlorophyll-a and -b content of leaves covered a range of 1-60 and 0.5-21 microg/cm(2), respectively. In contrast with previous results from hemispherical reflectance measurements, directional reflectance data does not correlate well with chlorophyll concentration. This is mainly due to the external reflectance (R(E)) at the leaf epidermis, caused by the mismatch of the refractive index at the air-epidermis and epidermis-inner layer boundary. The external reflectance can be identified with the blue flat reflectance between 380 and 480 nm. The inner reflectance (R(I)), obtained by subtracting the external reflectance from the measured spectra, was found to be linearly related to the logarithm of the chlorophyll content. Good fitting of the log (Chl) versus R(I)(lambda) curves were obtained for R(I) in the green band (around 550 nm) and close to the inflection point in the red edge (around 700 nm). The coefficient of determination, r(2), of curve fitting improved (up to 0.97) when the normalised inner reflectance NR(I)(lambda)=R(I)(lambda)/R(I)(lambda(0)), with lambda(0)>or=750 nm, was used instead of the absolute reflectance. The best indices for Chl, Chl-a and Chl-b determination were R(I)(542)/R(I)(750), R(I)(706)/R(I)(750) and R(I)(556)/R(I)(750), respectively. However, since the content of Chl-a relative to Chl-b was almost constant for the plants investigated, the two last indices must be further validated on leaves with a high variability in the Chl-a:Chl-b ratio. The error in the determination of chlorophyll content was found to be of the order of 10%. This value was lower than those obtained by applying the vegetation indices previously suggested. Therefore, the normalised inner reflectance in the green and in the red edge represents a more suitable index for the chlorophyll determination than those up to now used.

Chlorophyll↗
PubMed2001

The development of reflective learning in the context of health counselling and health promotion during nurse education.

AIMS AND BACKGROUND: The purpose of this follow-up study was to describe the development of reflective learning of 16 student nurses in the context of health counselling and promotion during clinical training of a 3-year nursing education programme in two Finnish polytechnics. The first aim was to analyse the levels of reflectivity in the student nurses' reflections on their videotaped counselling situations. The second aim was to explore the qualitative features of the reflective health counselling learning process in the context of health promotion. The theoretical background of the study was based on a transformative learning theory. METHODS: The data consisted of stimulated recall interviews with 16 student nurses conducted once a year between 1998 and 2000. The data were analysed using categorization and thematic analysis. FINDINGS: The findings of the study showed that half of the students in the research group reached the level of critical consciousness during their nursing education. The others remained at the level of consciousness. Two students who represented thoughtful action without reflection in the first study year were able to reach reflection and even critical reflection later during their education. The meaning schemas of counselling developed and were enriched when the students moved into the higher stages of reflection. There were features of an empowerment approach to health promotion only in the meaning schemas and perspectives of critical reflectors. CONCLUSIONS: These results may indicate that the empowerment approach to health promotion within the modern health promoting role of nurses requires critical reflection. Therefore, effective methods and evaluation tools of reflective learning are needed to support learning from practice via critical reflection.

Adolescent↗