SEARCH · PubMed Health

Results for “reflection”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,315 records · Page 73Linked to original sources

PubMed2001

Assessment of reflection pulse wave in patients with cardiomyopathy: evaluation of noninvasive measurement of wave intensity.

OBJECTIVE: We assessed the reflection pressure wave using noninvasive measurement of wave intensity (WI) in patients with cardiomyopathy. METHODS AND RESULTS: Subjects included 8 patients with hypertrophic cardiomyopathy (HCM group) and 10 patients with dilated cardiomyopathy (DCM group). Twelve healthy subjects were used as a control group. By using a combined Doppler and echo-tracking system, changes in vascular diameter (dD) and blood flow velocity (dV) were recorded simultaneously at the common carotid artery and dD x dV was measured as WI. In the components of WI, the positive component of early systolic phase (FE) and the negative component following FE (B) were significantly reduced in the DCM group. There was a significant positive correlation between FE and B in all 3 groups. The appearance time of B was significantly shorter in the HCM group and significantly longer in the DCM group compared with the control group. CONCLUSIONS: It was suggested that the value of the reflection pressure wave was influenced by the left ventricular contractility, and that the effect of the reflection pressure wave appeared earlier in patients with HCM and later in patients with DCM compared with the control subjects.

Blood Flow Velocity↗

PubMed1998

Coherent backscatter enhances reflection confocal microscopy.

When thin optically transparent specimens are grown on reflective substrates, contrast in reflection confocal microscopy is markedly enhanced. This enhanced contrast allows for the visualization of the thin filopodia and organelles contained within the neuritic processes of PC12 cells in culture. The characteristics of this contrast enhancement suggest that it arises because of interference between light scattered from the specimen and coherently backscattered illumination reflected off the substrate. This technique provides a method for visualizing living cells or other similarly transparent objects on opaque substrates in a nondestructive manner.

Animals↗

PubMedDate not supplied

[Measurement of stool composition in children with celiac disease using near-infrared reflectance spectroscopy].

Celiac disease is a disorder caused by gluten-sensitivity which, when manifested in its classical digestive form, frequently presents a malabsorption syndrome. The aim of this study is to evaluate the faecal composition in celiac children with malabsorption syndrome at the moment of diagnosis by using near-infrared reflectance spectroscopy and to compare it with that of healthy children. Thirty children with biopsy-proven celiac disease and 86 age-matched control children were recruited in our study. Children collected 24 hour faecal specimens and the analyses of faeces, water, fat, nitrogen and sugar were performed using near-infrared reflectance spectroscopy. Results show that celiac children daily eliminate a significantly greater quantity of water, fat, nitrogen and sugar than those in the control group. This might be due to the higher weight of faeces eliminated in the celiac group and, of course, to their celiac condition. Of all the nutrients, faecal fat is the substance which undergoes the greatest change, indicating that this nutrient continues to be the best parameter for dealing with patients with malabsorption syndrome. Near-infrared reflectance spectroscopy appears to be a useful tool for assessing stool composition in celiac disease.

English Abstract↗

PubMed1991

Younger and older adults' perception of the Wundt-Hering illusion as a function of display illumination and reflectance contrast.

Reflectance contrast (i.e., black as compared to grey figures on white ground) and display illumination were manipulated to vary the brightness contrast of Wundt-Hering figures. 16 college students and 16 older adults were presented with high, medium, and low reflectance contrast figures. For half the participants, display illumination was manipulated by covering the figures with a .5 yellow neutral density filter. Magnitude of the illusion increased significantly with increased reflectance contrast for college students, and college students were significantly more susceptible to the high contrast figures than were older adults. Display illumination had no effect on the performance of either group.

Adult↗

PubMed1999

Relationship of arithmetic problem solving and reflective-impulsive cognitive styles in third-grade students.

Different individuals approach mathematical problems in a variety of ways, with these different approaches also reflected in over-all cognitive styles. This investigation had two purposes, first, to determine whether good and poor arithmetic problem solvers differ substantially in cognitive style, and second, to determine whether the students, after training in techniques of solving arithmetic problems, improve their performance with no significant change in cognitive style. A total of 98 third graders participated (mean age 8.1 yr.; 50 boys, 48 girls). The Matching Familiar Figure Test was used to classify the students by cognitive style as either Reflective or Impulsive. Students also were given training with different problem-solving exercises for different arithmetic problems. The training program in problem-solving strategies did not improve performance on arithmetic problems for Reflective students; however, Impulsive students' performance did improve after training.

Child↗

PubMed2002

Reflectance spectrum of adipose tissue to trace grass feeding in sheep: influence of measurement site and shrinkage time after slaughter.

The signature of carotenoid pigments stored in the caudal fat has been used to discriminate carcasses of lambs raised on pasture from those fed concentrates. However, the literature reports higher concentration of carotenoids in perirenal than in caudal fat, and it is likely that carotenoid concentration in fat increases with shrinkage time. Our objectives were to investigate the effects of measurement site and shrinkage time after slaughter on the reliability of the discrimination between grass- and concentrate-fed lambs. Thirty-two lambs were fed concentrate-based diets (stall, n = 16) or grazed a natural pasture in France (grass, n = 16). The concentrate supply was regulated to have similar ADG between the two treatments. Periodically lambs weighing about 35 kg were slaughtered. Reflectance spectrum and lightness (L*), redness (a*), and yellowness (b*) were measured at slaughter and after 24 h of shrinkage in the subcutaneous caudal and in the perirenal fat. The spectra were translated to have a value of reflectance at 510 nm = 0 and the integral of the translated spectrum was calculated between 450 and 510 nm (i.e., the zone of light absorption by carotenoids). The integral value of subcutaneous caudal fat at slaughter differed between stall- and grass-fed lambs (P < 0.05) but was not reliable to discriminate between feeding treatments. After 24-h shrinkage, the discrimination was better but was uncertain for 50% of the lambs. The integral value of perirenal fat at slaughter allowed us to discriminate all the lambs fed concentrates (16) from all those fed pasture (16). After 24-h shrinkage, the discrimination based on perirenal fat was partially compromised; 21.9% of the animals were not correctly discriminated. The integral value of the translated spectrum was highly (P < 0.001) correlated with the fat yellowness (b*), but the b* value was not reliable to discriminate between feeding treatments. However, plotting yellowness (b*) against redness (a*) values allowed us to discriminate 31 out of 32 lambs. Measuring reflectance spectrum of perirenal fat at slaughter allowed for complete discrimination of grass-fed from stall-fed lambs. However, because the integral values were affected by shrinkage time, measurements should be rigorously made immediately after slaughter.

Abattoirs↗

PubMed2006

Rapid determination of Swiss cheese composition by Fourier transform infrared/attenuated total reflectance spectroscopy.

There is a need for rapid and simple techniques that can be used to predict the quality of cheese. The aim of this research was to develop a simple and rapid screening tool for monitoring Swiss cheese composition by using Fourier transform infrared spectroscopy. Twenty Swiss cheese samples from different manufacturers and degree of maturity were evaluated. Direct measurements of Swiss cheese slices (approximately 0.5 g) were made using a MIRacle 3-reflection diamond attenuated total reflectance (ATR) accessory. Reference methods for moisture (vacuum oven), protein content (Kjeldahl), and fat (Babcock) were used. Calibration models were developed based on a cross-validated (leave-one-out approach) partial least squares regression. The information-rich infrared spectral range for Swiss cheese samples was from 3,000 to 2,800 cm(-1) and 1,800 to 900 cm(-1). The performance statistics for cross-validated models gave estimates for standard error of cross-validation of 0.45, 0.25, and 0.21% for moisture, protein, and fat respectively, and correlation coefficients r > 0.96. Furthermore, the ATR infrared protocol allowed for the classification of cheeses according to manufacturer and aging based on unique spectral information, especially of carbonyl groups, probably due to their distinctive lipid composition. Attenuated total reflectance infrared spectroscopy allowed for the rapid (approximately 3-min analysis time) and accurate analysis of the composition of Swiss cheese. This technique could contribute to the development of simple and rapid protocols for monitoring complex biochemical changes, and predicting the final quality of the cheese.

Analysis of Variance↗

PubMed1999

Prediction of laboratory and in situ protein fractions in legume and grass silages using near-infrared reflectance spectroscopy.

Legume and grass silage samples (n = 121) were collected from commercial forage testing laboratories (trial 1). Samples were dried at 55 degrees C for 48 h, ground, scanned on a near-infrared reflectance spectrophotometer, and analyzed for crude protein (CP), soluble CP, acid detergent fiber (ADF) CP, and neutral detergent fiber (NDF) CP by wet chemistry methods. Sixty samples were selected for calibration development, and the remaining samples were used for equation validation. Near-infrared reflectance spectroscopy accurately predicted the CP content of the silages (R2 = 0.96), but prediction of soluble CP, ADF CP, and NDF CP was markedly less accurate. The coefficients of determination and standard errors of calibration for CP, ADF CP, NDF CP (percentage of DM), and soluble CP (percentage of CP) were as follows (0.96 and 0.80, 0.77 and 0.24, 0.72 and 0.71, and 0.82 and 4.40). In a second study, legume and grass silage samples (n = 32) were dried at 55 degrees C and ground (2 mm). Duplicate dacron bags containing 5 g of silage were incubated in the ventral rumen of three ruminally cannulated cows for 0, 3, 6, 12, 24, 48, and 72 h. In situ protein fractions, including rapidly degraded protein, slowly degraded protein, undegradable protein, degradation rate, and rumen-undegradable protein, were determined. Original samples were reground (1 mm) and scanned. Previously defined near-infrared spectroscopy calibration procedures were conducted. Coefficients of determination for in situ CP fractions were R2 > 0.92 with the exception of degradation rate (R2 = 0.87). Data suggest that in situ protein fractions are better predicted by near-infrared reflectance spectroscopy than by laboratory protein fractions.

Animals↗

PubMed2004

Depth rotation and mirror-image reflection reduce affective preference as well as recognition memory for pictures of novel objects.

In two experiments, the identification of novel 3-D objects was worse for depth-rotated and mirror-reflected views, compared with the study view in an implicit affective preference memory task, as well as in an explicit recognition memory task. In Experiment 1, recognition was worse and preference was lower when depth-rotated views of an object were paired with an unstudied object relative to trials when the study view of that object was shown. There was a similar trend for mirror-reflected views. In Experiment 2, the study view of an object was both recognized and preferred above chance when it was paired with either depth-rotated or mirror-reflected views of that object. These results suggest that view-sensitive representations of objects mediate performance in implicit, as well as explicit, memory tasks. The findings do not support the claim that separate episodic and structural description representations underlie performance in implicit and explicit memory tasks, respectively.

Affect↗

PubMed1995

Reflective practice: a focus for caring.

Nurse education has long been plagued by a perceived disjuncture between theory and practice. This paper explores the use of reflection as a mechanism to enable students of nursing to overcome this problem. A grounded theory approach is used to study a group of first-year students undertaking a 3-year undergraduate nursing course. Results of the study indicate that the use of the reflective processes of clinical debriefing and journaling does impact on the environment, the process, and the focus of learning. Anxiety associated with the learning environment was reduced through peer support and cooperation. In addition, students moved from a passive to a more active mode of learning. The most significant finding was that, over time, reflective processes resulted in the emergence of the client as the central focus of care.

Attitude of Health Personnel↗

PubMed1999

Using reflective thinking to develop personal professional philosophies.

Reflective thinking, closely related to critical thinking, is discussed as an essential teaching-learning process to help students in introductory professional courses develop personal professional philosophies. Reflective thinking opportunities used by nurse educators and teacher educators include students' own experiences, actual case studies, and media presentations. Using reflective thinking to develop personal professional philosophies helps students view themselves as future participants in their chosen professions.

Education, Nursing, Baccalaureate↗

PubMed2002

Merging reflective inquiry and self-study as a framework for enhancing the scholarship of teaching.

This article provides a model for improving teaching practice and developing new knowledge about teaching. The reflective self-study approach to pedagogical inquiry is rooted in reflective inquiry and self-study as found in nursing and education literature, respectively. The model offers nurse educators a mechanism by which they can better understand themselves as teachers and how their teaching affects students. Essential features of the model include interdisciplinarity and collaboration. Using the framework outlined in this article will help establish reflective self-study research as an accepted model of inquiry and further the dialogue on teaching in higher education.

Attitude of Health Personnel↗

PubMed2005

Reflective writing and nursing education.

Reflective writing is a valued tool for teaching nursing students and for documentation, support, and generation of nursing knowledge among experienced nurses. Expressive or reflective writing is becoming widely accepted in both professional and lay publications as a mechanism for coping with critical incidents. This article explores reflective writing as a tool for nursing education.

Education, Nursing↗

PubMed2001

Naturally processed HLA class II peptides reveal highly conserved immunogenic flanking region sequence preferences that reflect antigen processing rather than peptide-MHC interactions.

MHC class II heterodimers bind peptides 12-20 aa in length. The peptide flanking residues (PFRs) of these ligands extend from a central binding core consisting of nine amino acids. Increasing evidence suggests that the PFRs can alter the immunogenicity of T cell epitopes. We have previously noted that eluted peptide pool sequence data derived from an MHC class II Ag reflect patterns of enrichment not only in the core binding region but also in the PFRS: We sought to distinguish whether these enrichments reflect cellular processes or direct MHC-peptide interactions. Using the multiple sclerosis-associated allele HLA-DR2, pool sequence data from naturally processed ligands were compared with the patterns of enrichment obtained by binding semicombinatorial peptide libraries to empty HLA-DR2 molecules. Naturally processed ligands revealed patterns of enrichment reflecting both the binding motif of HLA-DR2 (position (P)1, aliphatic; P4, bulky hydrophobic; and P6, polar) as well as the nonbound flanking regions, including acidic residues at the N terminus and basic residues at the C terminus. These PFR enrichments were independent of MHC-peptide interactions. Further studies revealed similar patterns in nine other HLA alleles, with the C-terminal basic residues being as highly conserved as the previously described N-terminal prolines of MHC class II ligands. There is evidence that addition of C-terminal basic PFRs to known peptide epitopes is able to enhance both processing as well as T cell activation. Recognition of these allele-transcending patterns in the PFRs may prove useful in epitope identification and vaccine design.

Amino Acid Motifs↗

PubMedDate not supplied

Interactive journals: an educational strategy to promote reflection.

Reflection is an essential component of clinical reasoning in occupational therapy practice. The specialty area of mental health practice can elicit awareness and introspection for occupational therapy students at personal and professional levels. This article, a qualitative case study, describes the use of interactive journals in the mental health component of an undergraduate occupational therapy curriculum to foster and develop reflective skills. Students kept journals and submitted them biweekly; faculty members responded to the journals in writing within 24 hr. The journals were analyzed for common themes over the length of the course as well as at each biweekly period. Frequent themes were students' increased awareness and openness to the specialty area and positive changes in attitude associated with new knowledge and experiences. The results indicate that interactive journals in academic courses have the potential to be an effective strategy to promote reflection.

Curriculum↗

PubMed2006

"Blogging" about course concepts: using technology for reflective journaling in a communications class.

OBJECTIVE: Web log technology was applied to a reflective journaling exercise in a communication course during the second-professional year at the University of Mississippi School of Pharmacy, to encourage students to reflect on course concepts and apply them to the environment outside the classroom, and to assess their communication performance. DESIGN: Two Web log entries per week were required for full credit. Web logs were evaluated at three points during the term. At the end of the course, students evaluated the assignment using a 2-page survey instrument. ASSESSMENT: The assignment contributed to student learning and increased awareness level for approximately 40% of the class. Students had few complaints about the logistics of the assignment. CONCLUSION: The Web log technology was a useful tool for reflective journaling in this communications course. Future versions of the assignment will benefit from student feedback from this initial experience.

Communication↗

PubMed2004

Using a reflective diary to develop bracketing skills during a phenomenological investigation.

In this article, I have attempted to show how a reflective diary can be an effective tool for developing bracketing skills. A framework is necessary to guide reflective thought and encourage deep and critical thinking. My framework was influenced by the work of Schön (1987) and Johns (1984), and related to the concepts of reflecting 'on' and 'in' action, and identified specific learning that had taken place. Bracketing is an important part of the Husserlian approach to descriptive phenomenology. It is a continuous process that can be used in a number of ways. Within my study I used bracketing 'pre', 'in', and 'on' actions. In addition to using bracketing to facilitate the clear emergence of the phenomenon under investigation, it can also be used to help review the methodology of a study. Examples have been given within the article to highlight different situations where bracketing took place.

Attitude of Health Personnel↗

PubMed2005

A reflection on the use of semi-structured interviews.

Based on the her experiences of completing a doctoral study in which semi-structured interviews featured as the primary data collection method, Christine Dearnley offers a reflective insight into using semi-structured interviews as a method of data collection. The processes of reflection in, and on, the interview process are explored, and some of the ethical dilemmas that emerged during the study are reflected on. The practicalities of conducting semi-structured interviews are considered with a view to sharing new understandings of the process and its management.

Attitude of Health Personnel↗