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At least 19 recordsLinked to original sources
PubMed1976

Utilizing reflected countertransference Applying the reflection process as a teaching tool in supervision.

There are times when teaching cannot proceed through the abstract presentation of content and must progress by the demonstration of what is to be taught. This is true whenever a student is unable, for whatever reason, to appropriately apply such abstract material to the concrete task before him. This may be due to a number of factors, one of the most common of which is the lack of qualitatively similar experiences to which to refer. The teaching of complicated processes such as psychotherapy is an example, especially when the trainee is relatively unsophisticated and/or seems unable to abstract from discussion of blocking phenomena, where it may become necessary to "act in" the feeling tones which are to be the cues for the behaviour to be learned, instead of persisting with abstract interpretations. When, in supervision, a supervisee recreates the conditions existing in the therapeutic situation, this procedural behaviour is called the "Reflection Process". This process often appears to be unconsciously motivated by the need of the supervisee to solicit from the supervisor a practical demonstration which he does not know how to solicit otherwise. Even if the Reflection Process is due mainly to unresolved, unconscious conflicts of the supervisee, it can be a useful clue as to what transference-countertransference problems he is having difficulties with. The fact that such behaviour on the part of the supervisee may arise out of unresolved unconscious conflictual material should not become a reason for dismissing it. Instead, supervisors should become proficient at recognizing the countertransferential feelings in themselves, which can be an accurate reflection of the feelings troubling the supervisee in his dealings with this patient; and they should recognize the distress signal on the part of the supervisee, which can often be responded to constructively. In the supervision, the supervisor at times can, almost unwittingly, come to play the role which the supervised therapists plays in the supervised therapy and, if not aware of the Reflector Process, he may not realize that the countertransferential feelings which underly his assuming that role may not be primarily a response to the character of the therapist he is supervising but rather to that of the patient. They may also be a reflection of the process problem in the supervised therapy. It is not essential that this process be labeled in the supervision; what is essential is that its ramifications be recognized by the supervisor.

Allied Health Personnel↗
PubMed1991

Reflection in clinical teaching: an analysis of reflection-on-action and its implications for staffing residents.

In order to improve clinical teaching in the ambulatory care setting, clinical teachers need to know the range of instructional strategies available to them. One potentially useful strategy is that of reflection. In this paper, reflective practice will be described in the context of the professional training of physicians, with the purpose of improving clinical teaching. An example of reflective practice--a transcript of a video tape of an attending physician and a resident in a general internal medicine clinic--will be analyzed. In this transcript, reflective comments by both the attending physician and resident are integrated into the original dialogue.

Ambulatory Care↗
PubMed1992

Degradation, amorphization, and recrystallization of ion bombarded Si(111) surfaces studied by in situ reflection electron microscopy and reflection high energy electron diffraction techniques.

In this paper we report the effect of noble gas ions bombardment on the degradation of atomically flat Si(111) surfaces at room and high (400 degrees C-600 degrees C) temperatures. Reflection high energy electron diffraction (RHEED) and reflection electron microscopy (REM) have been used to characterize the topography and structure of the as-implanted and post annealed surface layers. It is shown that the fading of the specularly reflected beam is not directly related to the amorphization of the surface. This experimental study has also evidenced the difficulties one meets to regrow a defect-free material after amorphization by noble gas bombardment. For high temperature for which the amorphization is not possible, the surface loses its stepped structure and turns into a monocrystalline but atomically rough surface. This roughness is a function of substrate temperature.

Argon↗
PubMed1992

Characterization of the annealed (0001) surface of sapphire (alpha-Al2O3) and interaction with silver by reflection electron microscopy and scanning reflection electron microscopy.

Annealed (0001) surfaces of single-crystal sapphire (alpha-Al2O3) rod have been studied in the electron microscope using reflection electron microscopy (REM), scanning reflection electron microscopy (SREM), and reflection high energy electron diffraction (RHEED). Annealed surfaces of (0001) sapphire are vicinal and characterized by close-packed (0001)-oriented terraces separated by faceted multiple-height steps, with edges parallel to energetically preferred low-index directions (less than 1010 greater than and less than 1120 greater than). These structural features are not seen on cleaved surfaces or polished surfaces treated at temperatures less than 1,250 degrees C. Oxygen-annealing produces clean surfaces which prove useful for investigating the interaction of deposited metals with the (0001) sapphire. Both REM and SREM (with microdiffraction spots) techniques have been used to observe fine structure of flat Ag islands on the scale of 1-100 nm on the (0001)-oriented terraces as well as aggregations at the steps. A preliminary result on interaction with Cu is also included.

Aluminum Oxide↗
PubMed1992

Bloch wave treatment of symmetry and multiple beam cases in reflection high energy electron diffraction and reflection electron microscopy.

Bloch wave equations for the multiple beam cases in reflection high energy electron diffraction (RHEED) are derived from the integral equation by forward- and back-scattering Green function operators. A linearization is achieved through separation in a forward- and a back-scattering component for each beam. This leads to a set of fundamental equations similar to the transmission case, but with a non-Hermitian matrix, and the beams may be entered as either forward-, back-scattered, or both. The number of beams needed to be included in RHEED calculations is thus reduced, and so are the computing time and computer space required. The systematic row case, corresponding to reflections from planes parallel to the crystal surface, is treated in detail and illustrated by calculations of dispersion surfaces and rocking curves for Au(001). Symmetry relations for the systematic row and between reciprocal rows are discussed and illustrated.

Crystallography↗
PubMed1990

New sensitive light microscopical detection of colloidal gold on ultrathin sections by reflection contrast microscopy. Combination of reflection contrast and electron microscopy in post-embedding immunogold histochemistry.

One simple post-embedding method for combined light- and electron microscopy is presented. Different types of antigens in normal rat and mouse kidneys as well as in tissues from cases of experimental induced nephritis were stained after Lowicryl K4M embedding by an immunogold (silver) method. The (silver-enhanced) gold particles were visualized by light microscopy, e.g. bright-field (BFM)- and reflection contrast (RCM) microscopy, as well as by electron microscopy. The potentials of RCM visualization in this field were investigated, resulting in the successful detection of colloidal gold (15 nm) particles, or silver enhanced gold particles, on ultrathin sections. Furthermore, an increased detection sensitivity of RCM compared with BFM together with an increase in the sensitivity of the immunostaining by RCM visualization was found. The different ways to use RCM, alone or in combination with bright-field- or phase contrast microscopy for visualization of plastic sections varying in thickness, type of plastic and staining, are discussed.

Animals↗
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↗
PubMed1992

Reflection after delayed excitation in a computer model of a single fiber.

Reflection (reflected reentry) is a case of reentry in a one-dimensional structure, divided into proximal and distal segments, in which tissue excited by a wave front propagating in a forward direction is reexcited by electrical activity coming backward from the original direction of propagation. Cases of reflection have been demonstrated in Purkinje fibers and in ventricular muscle preparations containing multiple fibers. Several mechanisms possibly responsible for reflected reentry have been proposed. However, the difficulty in the interpretation of the experimental results, as well as the limited number of different conditions in which reflection was obtained, has kept open the question about conditions and mechanisms for reflection. We have developed a computer model in which reflection occurs. The model involves a single fiber and uses the DiFrancesco-Noble equations for the Purkinje fiber to model the ionic currents. The results show that reflection is possible in a single fiber and that diastolic depolarization (automaticity) is not a requirement for reflection. Active membrane responses to a just-above-threshold stimulus were important for achieving the necessary time delay. Systematic simulations showed further that reflection occurred only when the right coupling conditions linked a short or long proximal fiber to a short distal segment.

Action Potentials↗
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↗
PubMed1992

Increased systolic pressure in chronic uremia. Role of arterial wave reflections.

To assess the role of arterial wave reflections in the mechanism of systolic hypertension and altered pulsatile arterial dynamics in patients with end-stage renal disease (ESRD), 79 ESRD patients were compared with 73 age-matched control subjects with normal renal function and similar mean blood pressure. Wave reflections were investigated from the carotid pulse contour recorded by applanation tonometry using a Millar micromanometer-tipped probe. Wave reflections were quantified as the ratio (augmentation index, %) of the height of the late systolic peak to the total height of carotid pulse wave. Travel time of the reflected wave was timed from the foot of the pressure wave to the foot of the late systolic peak. Systolic and pulse pressure were increased in ESRD patients (p less than 0.001) and was not attributable to differences in left ventricular ejection pattern. The augmentation index was increased in ESRD patients (23.2 +/- 15.0 versus 9.8 +/- 15.6%; p less than 0.001) in association with a shorter travel time of reflected wave (109 +/- 24 versus 131 +/- 30 msec; p less than 0.001). Multiple regression analysis showed two principal factors associated (p less than 0.001) with the increase in augmentation index and shortened travel time of reflected wave: increased aortic pulse wave velocity and smaller stature with shorter body height in ESRD patients. The study points to the role of arterial wave reflections in the mechanisms producing alterations in pulsatile arterial dynamics in ESRD and is the first, through the mechanisms of early wave reflections, to show in humans that the increase in systolic and pulse pressures is associated with lesser body size.

Adult↗
PubMed1991

Measurement of mechanical properties of bone material in vitro by ultrasound reflection: methodology and comparison with ultrasound transmission.

An ultrasound reflection technique was designed and implemented to study the mechanical properties of bone material. The technique uses the fact that an ultrasound beam produced in water undergoes total internal reflection off a bone sample at a critical angle formally related to the velocity of a pressure wave in bone. When the plane of scattering is rotated around the normal to the sample surface, the critical angle varies with a periodic dependence dictated by the intrinsic symmetry of the bone structure at the point being examined. Most current measurements of sound velocity are made using transmission techniques. A double-blind intercomparison between this technique and a transmission technique, which was previously validated against tensile mechanical testing, was performed for samples of isotropic materials and of human cortical bone. Strong correlations were found for both sets of samples. For the isotropic materials the velocities were approximately equal, but for bone they were on average 11% higher in reflection than in transmission. This was the result both of the higher frequency employed in reflection (3.5 rather than 2.25 MHz) and of the different effects of sample imperfections on the two measurements. In particular, the reflection technique used in this work studied the surface of the sample, but the ultrasound beam in the transmission method propagated through its interior. In assessing the mechanical properties of bone specimens by ultrasound, the reflection technique samples a discrete bone surface element and the transmission method analyzes the entire volume of the specimen. Thus the reflection technique may yield a measure of the mechanical property of bone trabeculae that is largely unaffected by the mass of the entire specimen, but mass and the structural density of the specimen affect the transmission method.

Biomechanical Phenomena↗
PubMed1979

Quantitative reflection contrast microscopy of living cells.

Mammalian cells in culture (BHK-21, PtK2, Friend, human flia, and glioma cells) have been observed by reflection contrast microscopy. Images of cells photographed at two different wavelengths (546 and 436 nm) or at two different angles of incidence allowed discrimination between reflected light and light that was both reflected and modulated by interference. Interference is involved when a change in reflected intensity (relative to glass/medium background reflected intensity) occurs on changing either the illumination wavelength or the reflection incidence angle. In cases where interference occurs, refractive indices can be determined at points where the optical path difference is known, by solving the given interference equation. Where cells are at least 50 nm distant from the glass substrate, intensities are also influenced by that distance as well as by the light's angle of incidence and wavelength. The reflected intensity at the glass/medium interface is used as a standard in calculating the refractive index of the cortical cytoplasm. Refractive indices were found to be higher (1.38--1.40) at points of focal contact, where stress fibers terminate, than in areas of close contact (1.354--1.368). In areas of the cortical cytoplasm, between focal contacts, not adherent to the glass substrate, refractive indices between 1.353 and 1.368 were found. This was thought to result from a microfilamentous network within the cortical cytoplasm. Intimate attachment of cells to their substrate is assumed to be characterized by a lack of an intermediate layer of culture medium.

Animals↗
PubMed1978

Characterization of normal and abnormal pulmonary surface by reflected ultrasound.

The use of reflected ultrasound in the diagnosis of pulmonary disease has been limited due to the strong reflection and high absorption of acoustic energy by alveoli containing air. Our study reports the ultrasonic characteristics of normal and diseased pulmonary surface. Two measurements, the coefficient of pulmonary reflection and the tissue frequency signature, were studied with specially calibrated instuments. The coefficient of pulmonary reflection in 23 normal subjects was - 19.6 +/- 0.1 dB at 5.5 MHz. In ten patients with documented pulmonary emboli, the coefficient of pulmonary reflection was -47.4 +/- 0.1 dB, significantly less than normal (P less than 0.1). The tissue frequency signature in 18 normal subjects was specular at higher and nonspecular at lower frequencies, with a typical dip at 5.2 MHz. In patients with chronic obstructive pulmonary disease, the tissue frequency signature was flat, and the typical dip was absent. In patients with pulmonary emboli, the characteristic shape of the tissue frequency signature was preserved, but there was a generalized loss of magnitude of the reflection. Thus, our preliminary data indicate that reflected ultrasound provides a noninvasive method for differentiating normal from diseased pulmonary surfaces.

Animals↗
PubMed1992

The directional reflectance of the retinal nerve fiber layer of the toad.

Various optical methods for assessing the retinal nerve fiber layer (RNFL) depend on reflected light, but little is known about the characteristics of the RNFL as a reflecting structure. The authors investigated the angular dependence of light reflected by the unmyelinated nerve fibers of the toad eyecup using a small 500-nm light source that could illuminate the retina from various directions and a movable low-power microscope that imaged the retina onto a cooled charge-coupled device in a digital camera system. Measured areas had nerve fiber bundles separated by gaps. Therefore, the reflectance of a bundle alone could be determined from the difference in intensity between the bundle and an adjacent gap. The RNFL reflectance showed striking directional dependence; nerve fiber bundles seen when illuminated from one direction disappeared completely when illuminated from another. Light reflected by a bundle was confined to a conical sheet concentric with the axis of the bundle. The apex angle of the cone was twice the angle between the incident light and the bundle axis, and the orientation of the cone changed with the orientation of the RNFL. This behavior was consistent with the theory of light scattering by cylinders. Therefore, it was concluded that the RNFL reflectance arises from cylindric structures. These results have clinical significance for imaging the RNFL in the human eye because the apparent intensity of the RNFL will depend, not just on its thickness, but also on its orientation relative to the imaging system.

Animals↗
PubMed1992

Human cone-pigment spectral sensitivities and the reflectances of natural surfaces.

The evolution of visual pigment spectral sensitivities is probably influenced by the reflectance spectra of surfaces in the animal's environment. These reflectances, we conjecture, fall into three main classes: i. Most inorganic and many organic surfaces, including tree bark, dead leaves and animal melanin pigmentation, whose reflectance increases gradually as a function of wavelength. ii. Living leaves, which contain chlorophyll, have a sharp reflectance peak at about 555 nm. iii. Flowers, fruit and other signaling colours that have co-evolved with animal vision typically do not reflect strongly at the same wavelength as leaves, and present a colour contrast against a leafy background. These three spectral functions we call 'grey-red', 'leaf-green' and 'leaf-contrast' respectively. This simple categorisation allows us to interpret the spectral tuning of human cone pigments in a way that might not seem possible given the wide variety of colours present in nature. In particular L-(red) cones will capture the highest possible proportion of photons reflected by leaves, and M-(green) cones will capture about 10% fewer photons both from leaves and from 'grey-red' surfaces. These observations have some clear implications for our understanding of the evolution of trichomacy and the trade-off between chromatic and luminance vision in Old-World Primates.

Humans↗
PubMed1992

Experimental and clinical evaluation of a noninvasive reflectance pulse oximeter sensor.

The objective of this study was to evaluate a new reflectance pulse oximeter sensor. The prototype sensor consists of 8 light-emitting diode (LED) chips (4 at 665 nm and 4 at 820 nm) and a photodiode chip mounted on a single substrate. The 4 LED chips for each wavelength are spaced at 90-degree intervals around the substrate and at an equal radial distance from the photodiode chip. An optical barrier between the photodiode and LED chips prevents a direct coupling effect between them. Near-infrared LEDs (940 nm) in the sensor warm the tissue. The microthermocouple mounted on the sensor surface measures the temperature of the skin-sensor interface and maintains it at a present level by servoregulating the current in the 940-nm LEDs. An animal study and a clinical study were performed. In the animal study, 5 mongrel dogs (weight, 10-20 kg) were anesthetized, mechanically ventilated, and cannulated. In each animal, arterial oxygen saturation (SaO2) was measured continuously by a standard transmission oximeter probe placed on the dog's earlobe and a reflectance oximeter sensor placed on the dog's tongue. In the first phase of the experiment, signals from the reflectance sensor were recorded while the dog was immersed in ice water until its body temperature decreased to 30 degrees C. In the second phase, the animal's body temperature was normal, and the oxygen content of the ventilator was varied to alter the SaO2. In the clinical study, 18 critically ill patients were monitored perioperatively with the prototype reflectance sensor. The first phase of the study investigated the relationship between local skin temperature and the accuracy of oximeter readings with the reflectance sensor. Each measurement was taken at a high saturation level as a function of local skin temperature. The second phase of the study compared measurements of oxygen saturation by a reflectance oximeter (SpO2[r]) with those made by a co-oximeter (SaO2[IL]) and a standard transmission oximeter (SpO2[t]). Linear regression analysis was used to determine the degree of correlation between (1) the pulse amplitude and skin temperature; (2) SpO2(r) and SaO2(IL); and (3) SpO2(t) and SaO2(IL). Student's t test was used to determine the significance of each correlation. The mean and standard deviation of the differences were also computed. In the animal study, pulse amplitude levels increased concomitantly with skin temperature (at 665 nm, r = 0.9424; at 820 nm, r = 0.9834; p < 0.001) and SpO2(r) correlated well with SaO2(IL) (r = 0.982; SEE = 2.54%; p < 0.001).(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗