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At least 343 records · Page 19Linked to original sources

PubMed1992

Comparison of reflection and transmission pulse oximetry after open-heart surgery.

OBJECTIVE: To determine if there was a difference between reflection and transmission pulse oximeters in their ability to regain data display after hypothermia in patients recovering from open-heart surgery. DESIGN: Prospective, randomized, controlled study. PATIENTS: Nineteen adult patients scheduled for open-heart surgery were studied immediately after surgery in the ICU. INTERVENTIONS: Transmission and reflection sensors were used in random order in two simultaneously monitoring identical oximeters and probes. The time difference at the start of display between the oximeters was measured and the skin temperatures in the region of the probes, cardiac index, systolic BP, pulse pressure, and systemic vascular resistance index were recorded. RESULTS: The mean skin temperatures at the probe sites differed significantly (p = .001) at the moment of data acquisition. The mean forehead, ear lobe, and fingertip temperatures (simultaneously measured) were 33.9 degrees C, 31.8 degrees C, and 28.8 degrees C, respectively. The hemodynamic variables were comparable at the moment when the oximeters resumed display. The reflection probe was the first to resume function in 12 patients and the transmission probe was the first to resume function in four patients (p less than .02). The bias of the reflection probe was 1.4% (SD 2.2) and that of the transmission probe was -0.4% (SD 2.7). All the patients were normoxic throughout the study. CONCLUSION: The forehead reflection probe regained signal detection earlier than the transmission probe on the ear lobe in patients with compromised peripheral blood flow and cool periphery. This finding may be due to higher skin temperature at the reflection probe site, since the systemic hemodynamic conditions were equal at the time of the data acquisition of both sensors.

Adult↗

PubMed1979

Resentful and reflective coping with arbitrary authority and blood pressure: Detroit.

Two hypotheses about coping with an arbitrary authority, an angry boss, were tested: (1) styles of handling anger vary with social status, and (2) these styles are in turn related to blood pressure levels. Two styles of coping were tested: model R-R, Resentful vs. Reflective, and model I/O/R, Anger-In, Anger-Out, and Reflective. Handling an angry boss by Reflection is reported by more women than men, by those in middle-class areas rather than lower class, and does not vary by race. Working class report more use of Anger-Out than middle class who in turn report more use of Reflection. In general, the Anger-In response did not vary by race, sex, or area of residence (12-18%). For model R-R, Reflection of boss's anger was related to lower blood pressure when compared to Resentful responses, within sex, race, and residence groups. For model I/O/R, working-class, high stress persons who expressed Anger-Out showed the highest mean levels. Reflection is an appraisal response related to vascular and neural deceleration in stress experiments. This mode can be learned, and may aid in handling daily emotional-loaded stimuli to control blood pressure, along with learning a relaxation response.

Adaptation, Psychological↗

PubMed2006

Wideband reflectance norms for Caucasian and Chinese young adults.

OBJECTIVE: This study examined differences between the middle ears of two ethnic groups, Caucasian and Chinese young adults with normal hearing, using a new middle-ear measurement technique, wideband energy reflectance. The goal of this study was to determine whether the Chinese group had different middle-ear transmission properties than the Caucasian group. DESIGN: There were 126 subjects (237 ears) between the ages of 18 and 32 yr, with 62 subjects in the Caucasian group and 64 subjects in the Chinese group. Wideband energy reflectance data were gathered using Mimosa Acoustics (RMS system version 4.0.4.4) wideband reflectance (WBR) equipment. RESULTS: The Chinese group had significantly lower wideband energy reflectance than their Caucasian counterparts at higher frequencies; however, the Caucasian group had significantly lower energy reflectance at lower frequencies than the Chinese group. The Chinese group also had significantly lower admittance magnitude than the Caucasian group at lower frequencies. Because body size indices are more comparable between Caucasian females and Chinese males, the effect of body size could be potentially adjusted for by comparing the Caucasian female subjects with the Chinese male subjects. The differences observed between the Caucasian and the Chinese groups were no longer significant when the Caucasian female subjects were compared with the Chinese male subjects. Applying the Caucasian norms to four Caucasian adults with surgically confirmed otosclerosis resulted in an improved hit rate compared with the combined Caucasian and Chinese norms and the Chinese-only norms. CONCLUSION: Body size may play a role in the observed differences between the Caucasian and Chinese groups. The findings of this study suggest that further research is needed to investigate the effects of body size on wideband energy reflectance. It should be noted that factors other than body size may contribute to the observed differences. Chinese individuals may simply have different middle-ear characteristics than Caucasian individuals, which could affect WBR. In the meantime, overall test performance may be improved by using a more homogeneous norm when evaluating the middle ear of Caucasian or Chinese individuals with WBR.

Acoustic Stimulation↗

PubMed2003

The ubiquity of avian ultraviolet plumage reflectance.

Although several bird species have been shown to reflect ultraviolet (UV) light from their plumages, the incidence of UV reflectance, and therefore the potential for UV or UV-enhanced signals, across the avian tree of life is not known. In this study, we collected reflectance data from the plumages of 312 bird species representing 142 families. Our results demonstrate that all avian families possess plumages that reflect significant amounts of UV light. The ubiquity of UV reflectance indicates that all studies of avian behaviour, ecology and evolution involving plumage coloration would benefit from consideration of plumage reflectance in the UV portion of the electromagnetic spectrum. Additionally, we demonstrate the existence of cryptic UV plumage patches and cryptic dimorphism among birds.

Animals↗

PubMed2004

Anomalous reflections at photonic crystal surfaces.

We explore the reflection phenomena when a light beam propagating in a photonic crystal is incident upon the interfaces between the crystal and a uniform dielectric. We prove that a generalized wave-vector conservation relation still applies even when the interface is not aligned with special crystal directions. Using this conservation relation, we show that neither the phase velocity nor the group velocity directions of the reflected beam satisfies Snell's law. Rather, the system exhibits remarkable and unusual reflection effects. In particular, total internal reflection is absent except at discrete angular values. The direction of the reflected beam can also be pinned along special crystal directions, independent of the orientation of the interface. And finally, at glancing incidences, strong backward reflections may occur. These effects may be important for creating integrated photonic circuits, and for on-chip image transfer.

Journal Article↗

PubMed2002

Reflection-type hologram for atoms.

A cold metastable neon atomic beam was manipulated with a reflective amplitude hologram that was encoded on a silicon surface. A black-and-white pattern of atoms was reconstructed on a microchannel plate detector. The hologram used the enhanced quantum reflection developed by authors and was made of a two-dimensional array of rectangular low and high reflective cells. The surface of the high reflective cell was composed of regularly spaced roof-shaped ridges, while the low reflective cell was simply a flat surface. The hologram was the first demonstration of reflective atom-optical elements that used universal interaction between a neutral atom and solid surface.

Journal Article↗

PubMed2002

Specular reflection of matter waves from a rough mirror.

We present a high resolution study of the specularity of the atomic reflection from an evanescent wave mirror using velocity selective Raman transitions. We observed a double structure in the velocity distribution after reflection: a peak consistent with specular reflection and a diffuse reflection pedestal whose contribution decreases rapidly with increasing detuning. The diffuse reflection is due to two distinct effects: spontaneous emission in the evanescent wave and roughness in the evanescent wave potential whose amplitude is smaller than the de Broglie wavelength of the reflected atoms.

Journal Article↗

PubMed2006

Low velocity quantum reflection of Bose-Einstein condensates.

We study how interactions affect the quantum reflection of Bose-Einstein condensates. A patterned silicon surface with a square array of pillars resulted in high reflection probabilities. For incident velocities greater than 2.5 mm/s, our observations agreed with single-particle theory. At velocities below 2.5 mm/s, the measured reflection probability saturated near 60% rather than increasing towards unity as predicted by the accepted theoretical model. We extend the theory of quantum reflection to account for the mean-field interactions of a condensate which suppresses quantum reflection at low velocity. The reflected condensates show collective excitations as recently predicted.

Journal Article↗

PubMed1978

Physiological Effects of Surface Waxes: I. Light Reflectance for Glaucous and Nonglaucous Picea pungens.

Foliage reflectance was studied on glaucous and nonglaucous foliage of blue spruce (Picea pungens Engel.). Current-year and 1-year-old glaucous and nonglaucous foliage from mature trees and seedling glaucous and nonglaucous foliage had similar reflectance patterns in the 350 to 800 nanometer region. The highest reflectance was in the 750 to 800 nanometer region and the lowest reflectance was in the 670 nanometer region. Glaucous foliage had a higher percentage of light reflectance at all of the wavelengths of light. The largest difference of reflectance between glaucous and nonglaucous foliage was in the 350 nanometer region with a general decline in the difference to the smallest difference at the 800 nanometer region.

Journal Article↗

PubMed2003

Diffuse scattering and short-range order in uranium iodine phthalocyanine [U1-xPc(2)]I2-y and the X-ray structure analysis of crystals with diffuse superstructure reflections.

Crystals of uranium iodine phthalocyanine present an example of a disordered commensurate modulated structure of the intergrowth type. The short-range order of both uranium ions and iodine chains [I(3)(-)](n) has been analysed by Reverse Monte Carlo (RMC) simulation of X-ray diffuse scattering. The diffraction pattern of uranium iodine phthalocyanine contains diffuse superstructure reflections. In the routine crystal structure analysis diffuse superstructure reflections may be either omitted or measured and classified along with other Bragg reflections. The crystal structure of uranium iodine phthalocyanine is an example of such ambiguity. The crystal structures of two specimens of [U(1-x)Pc(2)]I(2-y) with slightly different composition have been published in the literature with different space groups and unit cells. We have shown that the structure of both specimens differs only in the degree of short-range order and is isostructural with [YbPc(2)]I(2). We have also shown that while the omission of diffuse reflections results in the average crystal structure, the treatment of these reflections as normal Bragg reflections is incorrect and produces the structure averaged over a limited small range.

Journal Article↗

PubMed2006

On the use of CCD area detectors for high-resolution specular X-ray reflectivity.

The use and application of charge coupled device (CCD) area detectors for high-resolution specular X-ray reflectivity is discussed. Direct comparison of high-resolution specular X-ray reflectivity data measured with CCD area detectors and traditional X-ray scintillator ('point') detectors demonstrates that the use of CCD detectors leads to a substantial (approximately 30-fold) reduction in data acquisition rates because of the elimination of the need to scan the sample to distinguish signal from background. The angular resolution with a CCD detector is also improved by a factor of approximately 3. The ability to probe the large dynamic range inherent to high-resolution X-ray reflectivity data in the specular reflection geometry was demonstrated with measurements of the orthoclase (001)- and alpha-Al2O3 (012)-water interfaces, with measured reflectivity signals varying by a factor of approximately 10(6) without the use of any beam attenuators. Statistical errors in the reflectivity signal are also derived and directly compared with the repeatability of the measurements.

Equipment Design↗

PubMed1998

XAFS spectra from reflectivity measurements.

The reflectivity of TiSi(2) films was measured as a function of photon energy E at the Ti K-edge region at a glancing angle theta close to the critical angle theta(C) of total reflection. TiSi(2) silicide films (about 30 nm thickness) were prepared by silicidation of Ti thin films deposited on Si(001) substrates. Since the Fresnel reflectivity R(theta,E) is a function of the dispersion delta(E) and of the absorption beta(E), the absorption beta(E) which carries the XAFS signal can be solved as beta(theta,delta,R) for observed reflectivity R and for estimated delta. The dispersion delta(E) is related to the absorption beta(E) by the Kramers-Kronig (K-K) relations since the refractive index is n(E) = 1 - delta(E) - ibeta(E). beta(E) was calculated from the observed reflectivity R(theta,E) using theoretical values for initial delta(E). Titanium K-edge XAFS for TiSi(2) was extracted from the reflectivity by 'ReflXAFS'.

Journal Article↗

PubMed2002

Very small IF resonator filters using reflection of shear horizontal wave at free edges of substrate.

A shear horizontal (SH) wave has the characteristic of complete reflection at the free edges of a substrate with a large dielectric constant. A conventional surface acoustic wave (SAW) resonator filter requires reflectors consisting of numerous grating fingers on both sides of interdigital transducers (IDTs). On the contrary, it is considered that small-sized and low loss resonator filters without reflectors consisting of grating fingers can be realized by exploiting this characteristic of the SH wave or the Bleustein-Gulyaev-Shimizu (BGS) wave. There are two types of resonator filters: transversely coupled and longitudinally coupled. No transversely coupled filters (neither conventional nor edge-reflection) using the SH wave on a single-crystal substrate have been realized until now, because two transverse modes (symmetrical and asymmetrical modes) are not easily coupled. However, the authors have realized small low loss transversely coupled resonator filters in the range of 25 to 52 MHz using edge reflections of the BGS wave on piezoelectric ceramic (PZT: Pb(Zr,Ti)O3) substrates for the first time by developing methods by which the two transverse modes could be coupled. On the other hand, longitudinally coupled resonator filters using edge reflection of the SH or BGS wave always have large spurious responses because of the even modes in the out-of-band range, because the frequencies of even modes do not coincide with the nulls of the frequency spectra of the IDTs. Consequently, longitudinally coupled resonator filters using the edge reflection of the SH wave have not been realized. By developing a method of reducing the spurious responses without increasing of the insertion loss, the authors have realized small low loss longitudinally coupled resonator filters in the range of 40 to 190 MHz using edge reflection of BGS or SH waves on PZT or 36 degrees-rotated-Y X-propagation LiTaO3 substrates for the first time. Despite being intermediate frequency (IF) filters, their package (3 x 3 x 1.03 mm3) sizes are as small as those of radio frequency (RF) SAW filters.

Journal Article↗

PubMed1992

Anxiety, accuracy and reflection: the limits of professional development.

Reflection is a key concept in the development and maintenance of nursing expertise in theory and practice, yet commentators have rarely examined difficulties associated with it. This paper describes the role of reflection in nursing and relates it to information-processing accounts of human memory. The issues raised by the role of memory in mediating reflection are discussed, in the context of an examination of the importance of accuracy in reflection-on-practice. It is argued that anxiety is of particular importance in mediating accurate reflection. Whilst it is concluded that reflection is inherently flawed, a range of tactics to enhance it are explored, with particular emphasis on anxiety reduction and reduction of the burden of the memory task.

Anxiety↗

PubMed2005

Evaluation of a reflective practice intervention to enhance family care.

AIM: This paper discusses the design, evaluation and outcomes of a reflective practice intervention (RPI) that taught paediatric critical care nurses how to incorporate a family intervention into their practice. BACKGROUND: The literature on reflective practice contains numerous descriptions of reflective practice and various frameworks on how to engage in reflective practice. Additionally, there has been wide debate about the benefits of and problems with the use of reflective practice. However, few empirical studies have been done to evaluate its effectiveness in changing nursing practice. METHOD: Van Manen's phenomenological research approach was adapted for use in this study. This approach was consistent with the experiential nature of reflective practice. Interviews were conducted with eight staff nurse participants after the RPI to determine changes in family practice. Analysis of the interview text produced three essential themes. FINDINGS: Three interrelated themes describe change in the nurses' experiences as a result of participating in the RPI: (1) acknowledging and re-framing preconceived ideas about families, (2) recognizing the meaning of family stress and (3) beginning to incorporate the family into nursing care. CONCLUSIONS: The RPI stimulated double loop learning that changed paediatric critical care nurses' attitudes about family, enhanced their communication and ability to build trusting relationships with families and brought about a new appreciation of the uniqueness of family stress. There was a new integration of family care into the nurses' practice as a result of the intervention.

Adult↗

PubMed1984

Surface reflection interference microscopy: a new method for visualizing cytoskeletal components by light microscopy.

Surface reflection interference microscopy of detergent resistant residues of cultured cells stained with protein dyes can be used to obtain high resolution images of the cytoskeleton. We have compared the images obtained using different dyes and have examined the effect of four of these dyes on the visualization of different parts of the cytoskeleton in detail. The dependence of contrast of the images obtained on the illuminating numerical aperture and the wavelength of incident light was determined. Staining with Acid Yellow 36, Guinea Green B and Naphtol Blue Black produces images from the entire cytoskeleton and contrast in these images is relatively insensitive to changes in the incident wavelength. Coomassie Brilliant Blue R250 images, on the other hand, result primarily from reflection from the lower surface of the cytoskeleton and the contrast of these images is sensitive to changes in incident wavelength dropping abruptly in the region of the transmission peak of the stain. From the different spectral sensitivities of the reflection images obtained and from differential interference effects at low and high illuminating numerical apertures, we conclude that the reflection images obtained using the first three stains result from modulation of the reflection by interference effects. In contrast, in the case of Coomassie Brilliant Blue R250 the resulting image originates mainly from selective reflection of wavelength near the absorption range of the dye.

Animals↗

PubMed2005

Opening up: psychiatric nurses' experiences of participating in reflection groups focusing on the use of coercion.

Psychiatric staff report that the use of coercion towards patients in psychiatric care engenders feelings of discomfort and conflicts. The aim of this study was to describe psychiatric nurses' experiences of participating in reflection groups focused on the use of coercion, in relation to their views regarding systematic clinical supervision and staff support. Twenty-one nurses who had participated in reflection groups were interviewed retrospectively. The structured interview focused on: (i) their views of clinical supervision and support in general; (ii) their views of clinical supervision and support specifically concerning the use of coercion; and (iii) their experiences of participating in groups reflecting the use of coercion. Nurses were largely positive about participating in reflection groups, as expressed in the subthemes: having time for reflection; being confirmed; gaining new perspectives; sharing fellowship with colleagues; and relating more effectively to patients. Complications concerning participation in the reflection groups and other forms of clinical supervision as reported by nurses were: providing time for participation; having a common aim; being vulnerable in difficult situations; and assuming that the need for supervision and support could indicate that they were not coping with their job.

Adult↗

PubMed1994

VDT screen reflections and accommodation response.

Reflections in computer screens are imaged behind the screen and therefore potentially create a conflicting cue to appropriate accommodation response to the plane of screen. We investigated the effect of screen reflections on accommodation response by producing reflections (1.33 D accommodation demand) surrounding and overlying the fixation point (2 D accommodation demand) in the screen. We have found little evidence that reflections in visual display terminal screens can influence the accuracy of the users' accommodation responses under normal binocular viewing conditions. The accuracy of the accommodation response was not significantly influenced by the position of the reflections, the presence of surrounding text (peripheral cues), or the subjects' dark focus level. The variability of accommodation response did not significantly change under the various test conditions. However, accommodation errors were apparent to a small degree (< 0.25 D) under some monocular viewing conditions in the presence of screen reflections.

Accommodation, Ocular↗