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PubMed2005

Eye use during viewing a reflection: behavioural lateralisation in zebrafish larvae.

Development of visual lateralisation was studied in zebrafish larvae of an outbred strain when examining their own reflection in a mirror. There was significant left eye preference at all ages studied. A decrease in left eye use around 14 days, followed by a later increase at 21 days, parallels similar but differently timed shifts in the domestic chick. Age-dependent shifts in the likelihood of control by one or other eye system may be responsible. Larvae tested at 26 days of age with unfamiliar conspecifics of similar age also used the left eye (LE). Larvae of another strain (TupLF) also LE viewing of their reflection, although this was confined to the first or first and second minutes of the test rather than lasting through 10 min. The reflection differs from prior experience of fellows in the timing and character of its movements relative to those of the larva. Specialisation of the left eye system for the assessment of novelty, which is present in zebrafish, just as in many other vertebrates, probably therefore explains left eye use in the mirror test. Reasons why strains might differ in the length of time that they devote to assessment of the reflection are discussed.

Analysis of Variance↗

PubMed2004

Biochemical markers of bone formation reflect endosteal bone loss in elderly men--MINOS study.

In the skeleton of elderly men, two opposite activities occur: bone loss at the endosteal envelope, which increases bone fragility, and periosteal apposition, which improves bending strength of bone. Both may contribute to serum bone formation markers although they have an opposite effect on bone fragility. The aim of this study was to determine if circulating bone formation markers reflect periosteal bone formation and endosteal bone remodelling in 640 men aged 55-85 years belonging to the MINOS cohort. We measured biochemical markers of bone formation (osteocalcin, bone alkaline phosphatase, N-terminal extension propeptide of type I collagen) and bone resorption (urinary and serum beta-isomerised C-terminal telopeptide of collagen type I, total and free deoxypyridinoline). Parameters of bone size (cross-sectional surface of third lumbar vertebral body measured by X-ray, projected areas of total hip, femoral neck, radius and ulna measured by dual-energy X-ray absorptiometry) increased with age (r = 0.20-0.32, P < 0.0001). In contrast, parameters related to bone loss (areal bone mineral density [aBMD], volumetric bone mineral density [vBMD] and cortical thickness) and determined mainly by bone resorption, decreased with ageing (r = -0.14 to -0.23, P < 0.005-0.0001). Men in the highest quartile of bone resorption markers had lower aBMD (3.8-10.2%, P < 0.05-0.0001), lower vBMD (3.9-13.0%, P < 0.05-0.0001), and lower cortical thickness (1.5-9.6%, P < 0.05-0.0001) than men in the lowest quartile. Markers of bone resorption were not significantly associated with estimates of bone size at any skeletal site. Markers of bone formation were not associated with estimates of periosteal formation after adjustment for covariates. In contrast, men in the highest quartile of the bone formation markers had significantly lower aBMD (4.0-11.7%, P < 0.05-0.0001), lower vBMD (4.2-16.3, P < 0.05-0.0001) and lower cortical thickness (4.0-7.4%, P < 0.05-0.0001) than men in the lowest quartile. In summary, serum levels of bone formation markers are negatively correlated with the estimates of endosteal bone loss. In contrast, they disclose no association with parameters reflecting periosteal apposition. Thus, in elderly men, bone formation markers reflect endosteal bone remodelling, probably because of the coupling between resorption and formation activities. In contrast, they do not reflect the periosteal bone formation, probably because the periosteal surface is smaller and has a slower remodelling rate than the endosteal surface.

Absorptiometry, Photon↗

PubMed2006

Glycated hemoglobin and albumin reflect nestling growth and condition in American kestrels.

Blood chemistry can be used to assess physiological state and condition. Levels of glycated hemoglobin (GHb), which integrates blood glucose levels over a period of weeks, may provide a way to assess resource intake. I tested whether GHb reflects offspring quality by comparing growth rates of nestling American kestrels (Falco sparverius) with GHb levels at 24 days of age. Nestlings that gained structural size faster had higher levels of GHb than did slower growing nestlings. There was no difference in GHb levels between males and females, although females are larger. In addition, I tested whether albumin levels, a measure of protein storage, were correlated with nestling growth and body condition (reflected in residual body mass). Larger individuals, measured by both absolute body mass and by residual body mass, had larger levels of albumin. This was due in part to females having higher albumin levels. Interestingly, there was no correlation between GHb and albumin, suggesting that both measures are necessary to assess physical condition in nestling kestrels. These results suggest that blood chemistry can reflect offspring condition measures and may provide a way to assess offspring quality that reflects conditions experienced by offspring over longer periods through measurements at a single time point.

Albumins↗

PubMed2004

Handedness and the fringe of consciousness: strong handers ruminate while mixed handers self-reflect.

Previous research found that mixed handers (i.e., those that are more ambidextrous) were more likely than strong handers to update their beliefs (Niebauer, Aselage, & Schutte, 2002). It was assumed that this was due to greater degrees of communication between the two cerebral hemispheres in mixed handers. Niebauer and Garvey (2004) made connections between this model of updating beliefs and metacognitive processing. The current work proposes that variations in interhemispheric interaction (as measured by degree of handedness) contribute to differences in consciousness, specifically when consciousness is used in rumination versus the metacognitive task of self-reflection. Using the Rumination-Reflection Questionnaire (Trapnell & Campbell, 1999), predictions were supported such that strong handedness was associated with self-rumination; whereas, mixed handedness was associated with increased self-reflection p values<.01, (N=255). James's (1890) concept of the "fringe of consciousness" is used to make connections between metacognition, updating beliefs, and self-reflection. Several studies are reviewed suggesting that mixed handers experience fringe consciousness to a greater degree than strong handers.

Adult↗

PubMed2005

Abnormal oral mucosal light reflectance in bronchopulmonary dysplasia.

BACKGROUND: Bronchopulmonary dysplasia (BPD) is an important cause of mortality and morbidity in preterm infants. A disordered vascular development and a decreased production of angiogenic factors have been recently reported in the condition. Extracellular matrix (ECM) is known to play an important role on angiogenesis and blood vessel geometry and changes in ECM components have been previously reported in experimental models and patients with BPD. Here, we aimed to assess the potential value of light reflectance on the oral mucosa in detecting infants who will develop BPD. METHODS: A total of 75 preterm newborns (gestational age: 27.7 +/- 2.8 weeks, birth weight: 870 +/- 145 g) were recruited to the study, of whom 25 developed BPD (gestational age: 26.9 +/- 3.0 weeks, birth weight: 855 +/- 150 g). Reflectance was measured on the postnatal days 1 and 28, using high-resolution photographs of the lower gingival and vestibular oral mucosa, using imaging spectrophotometry in the 400-700 nm wavelength electromagnetic spectral range. The median of artefact- and vessel-free areas was n = 78 (interquartile range: 59-88). Median range values were comparable for both groups: BPD-positive infants, median 77 (interquartile: 60-90) vs. control infants, median 74 (interquartile: 62-92). The predictive accuracy of oral spectrophotometry was calculated using receiver operating characteristic curve analysis. RESULTS: BPD patients showed significantly lower light reflectance values in the red (610-700 nm, P < 0.0001), with higher values in the violet (400 nm, P = 0.0056; 430 nm, P=0.014), and blue-green (480-500 nm, P < or = 0.024) sections of the spectrum already on the first day of life. A low reflectance value in the 640-700 nm wavelengths interval was found to identify BPD patients with 100% sensitivity and 100% specificity (640 nm: cutoff < or = 44.91%; 650 nm: < or = 45.64%; 660 nm: < or = 46.56%; 670 nm: < or = 47.14%; 680 nm: < or = 47.56%; 690 nm: < or = 48.95%; 700 nm: < or = 50.81%). CONCLUSIONS: These findings indicate the presence of previously unrecognised, early abnormalities in the average optical properties of the oral mucosa from infants developing BPD.

Bronchopulmonary Dysplasia↗

PubMed2004

UVR reflections at the surface of the eye.

Sunlight plays an etiological role in the formation of skin cancers [Phys. Med. Biol. 24 (1979) 931]. Non-melanoma skin cancers commonly arise in sun-exposed parts of the body, especially on the head and neck regions [Int. J. Dermatol. 34 (6) (1995) 398] although the amount of sun exposure that is required for the formation of skin cancers is still unknown. It is known that the larger the dose of UVR, and in particular the erythemal action spectrum, the more likely it is to form the non-melanoma skin cancers, basal cell carcinomas (BCCs) and squamous cell carcinomas (SCCs). A number of regions on the face exhibit a seemingly high rate of occurrence of BCCs in relation to apparent direct exposure. One of these regions is the inner canthus located next to the eye on the bridge of the nose which has an occurrence rate of 7.1% of all BCCs that occur on the head and neck [Gen. Surg. 51 (6) (1981) 576, Aust. NZ J. Surg. 60 (1990) 855, Malignant Skin Tumours, Longman Singapore Publishers, Singapore, 1991]. The inner canthus seems to be well protected from large direct doses of ultraviolet radiation (UVR) and to explain the higher incidence of BCCs on the inner canthus it is proposed that a significant proportion of the incident UVR on the eye and surrounding areas is reflected onto the inner canthus. This paper presents a preliminary investigation of the contribution of UVR reflected to the inner canthus from the tear film covering the eye using a two-dimensional theoretical model on the horizontal plane (0 degrees elevation angle). Calculations show that up to 30% of the total radiation that is received on the inner canthus on a cellular level in this plane is reflected from the eye. A three-dimensional computer-generated ray tracing model of the eye, surrounding facial features and the inner canthus is being created to investigate the effect that these reflections have on the total dose of UVR.

Basal Cell Carcinoma↗

PubMed2006

Resolving surface details with reflection and fluorescence video-confocal profilometry.

Video-confocal profilometry has been exploited to characterize reflecting and non-reflecting surfaces in materials with tilted and corrugated areas. An alternative method based on fluorescence detection has been developed and tested to characterize metal surfaces modified by intense laser irradiation. Combined representations of surface topography have been obtained on the basis of both reflectance and fluorescence signals. A discussion of results and problems encountered in reflection and fluorescence based techniques is provided.

Journal Article↗

PubMed2006

Long-term monitoring of biofilm growth and disinfection using a quartz crystal microbalance and reflectance measurements.

A biofilm reactor was constructed to monitor the long-term growth and removal of biofilms as monitored by the use of a quartz crystal microbalance (QCM) and a novel optical method. The optical method measures the reflectance of white light off the surface of the quartz crystal microbalance electrode (gold) for determination of the biofilm thickness. Biofilm growth of Pseudomonas aeruginosa (PA) on the surface was used as a model system. Bioreactors were monitored for over 6 days. Expressing the QCM data as the ratio of changes in resistance to changes in frequency (DeltaR/Deltaf) facilitated the comparison of individual biofilm reactor runs. The various stages of biofilm growth and adaptation to low nutrients showed consistent characteristic changes in the DeltaR/Deltaf ratio, a parameter that reflects changes in the viscoelastic properties of the biofilm. The utility of white light reflectance for thickness measurements was shown for those stages of biofilm growth when the solution was not turbid due to high numbers of unattached cells. The thickness of the biofilms after 6 days ranged from 48 mum to 68 mum. Removal of the biofilm by a disinfectant (chlorine) was also measured in real time. The combination of QCM and reflectance allowed us to monitor in real time changes in the viscoelastic properties and thickness of biofilms over long periods of time.

Biofilms↗

PubMed2004

Remembrance of things past: the utilisation of context dependant and autobiographical recall as means of enhancing reflection on action in nursing.

Reflection on action is widely accepted as a means of developing an individual's experience and professional and scientific knowledge [Accident and Emergency Nursing 4 (1996) 135]. Reflection can occur when a nursing event is examined and explored which may lead to the individual acquiring new perspectives and new knowledge regarding the event. This paper contends that the exploration of an event in practice can be better understood if viewed in the context of previous similar experiences. A five stage structured process is suggested whereby the nurse intentionally returns to former places and recreates previously experienced affective states with the purpose of accessing context and state dependent memories. These rediscovered remembrances can then serve as the raw material for reflection on nursing problems and dilemmas. A comparison of the current problem with the past experience may lead to new learning and a deepening of the reflective process. The seminal work of Marcel Proust is referred to in order to illustrate the process and examples from practice are also identified.

Association↗

PubMed2005

A study on the protection to relics and the related problems with diffuse reflectance spectroscopy.

The application of diffuse reflectance spectroscopy to relic protection is studied by using a self-made fiber optics reflectance spectrophotometer. The major work done includes: (1) the composition of pigment on colored relics and its changes are identified; (2) the change on metal surface is monitored; (3) the reflectance spectrum characteristics of relic protection materials are studied. The results tell that diffuse reflectance spectroscopy is a new protection technique, characterized by its quickness and non-destructiveness to the relic.

Chemistry Techniques, Analytical↗

PubMed2004

Abnormal oral mucosal light reflectance: a new clinical sign of Ehlers-Danlos syndrome.

Ehlers-Danlos syndrome (EDS) is a major inherited connective tissue disorder leading to an impaired extracellular matrix structure. Although several odontostomatologic signs have been reported, their diagnostic accuracy remains to be ascertained. We tested the hypothesis that EDS is associated with an abnormal reflectance of the oral mucosa. Twelve patients with EDS-II or EDS-III and 12 age- and gender-matched controls were examined. Reflectance of the lower gingival and vestibular oral mucosa in the optical spectrum was measured using an imaging spectrophotometer. EDS patients showed significantly higher reflectance values in the 400-590 nm wavelengths (P 10.51% at the 400 nm wavelength identified the EDS patients with 100% sensitivity and 100% specificity. These findings indicate that an abnormal oral mucosal reflectance is a previously unrecognized clinical marker of EDS.

Adolescent↗

PubMed2004

Near-field magneto-optical analysis in reflection mode SNOM.

Observation of magnetic domains with in-plane magnetisations is demonstrated by scanning near-field optical microscopy (SNOM) in reflection mode. The longitudinal and transverse magneto-optical Kerr effects are employed as the contrast mechanisms; these are observed as either a change in the polarisation of the reflected light or reflectance, depending on magnetisation direction. SNOM images of Co and Ni thin films show magneto-optical contrast depending on polarisation of the incident and detected light. For the smooth cobalt thin films, the orientation for magnetic domains is estimated, based on the correlation between the contrasts in SNOM images obtained in different polarisation configurations and the directions of the magnetic vectors of the incident and reflected light. For the nickel films with pronounced topographic structures, the resulting near-field polarisation dependencies are more complicated, suggesting that the magneto-optical contrast in SNOM images are affected by the topographic cross-talk due to the depolarisation effects on surface topographic features.

Journal Article↗

PubMed2005

Evaluation of interface wave velocity, reflection coefficients and interfacial stiffnesses of contacting surfaces.

The phase velocity of the antisymmetric-mode interface wave as well as the longitudinal and shear wave reflection coefficients have been measured for contacting poly(methyl methacrylate) (PMMA) surfaces subjected to different contact pressures. It has been found that while the reflection coefficients decrease as the contact pressure is increased, the phase velocity of the interface wave increases from that of the Rayleigh wave toward that of the bulk shear wave. From these measurements, the normal and tangential interfacial stiffnesses of the contacting PMMA surfaces have been evaluated as functions of the contact pressure. As a result, the two independent procedures to evaluate the tangential stiffness, namely, from the interface wave velocity and from the shear wave reflection measurements, have yielded mutually consistent results. Furthermore, it has been found that the tangential/normal stiffness ratio and the shear/longitudinal reflection ratio of the contact interface are consistent with the predictions of an existing theoretical model for kissing bond interfaces.

Journal Article↗

PubMed2006

Measurement of the viscosity-density product using multiple reflections of ultrasonic shear horizontal waves.

We have developed an on-line computer-controlled sensor, based on ultrasound reflection measurements, to determine the product of the viscosity and density of a liquid or slurry for Newtonian fluids and the shear impedance of the liquid for non-Newtonian fluids. A 14 MHz shear wave transducer is bonded to one side of a 45-90 degrees fused silica wedge and the base is in contract with the liquid. Twenty-eight echoes were observed due to the multiple reflections of an ultrasonic shear horizontal (SH) wave within the wedge. The fast Fourier transform of each echo was obtained for a liquid and for water, which serves as the calibration fluid, and the reflection coefficient at the solid-liquid interface was obtained. Data were obtained for 11 sugar water solutions ranging in concentration from 10% to 66% by weight. The viscosity values are shown to be in good agreement with those obtained independently using a laboratory viscometer. The data acquisition time is 14s and this can be reduced by judicious selection of the echoes for determining the reflection coefficient. The measurement of the density results in a determination of the viscosity for Newtonian fluids or the shear wave velocity for non-Newtonian fluids. The sensor can be deployed for process control in a pipeline, with the base of the wedge as part of the pipeline wall, or immersed in a tank.

Journal Article↗

PubMed2006

Fast beating null strip during the reflection of pulsed Gaussian beams incident at the Rayleigh angle.

It is well known that harmonic bounded Gaussian beams undergo a transformation into two bounded beams upon reflection on a solid immersed in a liquid. The effect is known as the Schoch effect and can be found at the Rayleigh angle for thick plates and at the different Lamb angles for thin plates. Here, a study is made on the effect of pulsed Gaussian beams reflected on solids. It is found experimentally that the Rayleigh wave phenomenon still generates two reflected bounded beams, whereas Lamb wave phenomena do not generate this effect. This fact may be explained intuitively by realizing that the Rayleigh phenomenon is a coincidental phenomenon that is generated in situ, whereas the Lamb wave phenomenon is a non-coincidental phenomenon that is generated only after incident sound is influenced by both sides of a thin plate. Another explanation is the fact that Rayleigh waves are not dispersive, whereas stimulation and propagation of Lamb waves is frequency dependent. A pulse contains many frequencies and therefore only a fraction of the incident pulse is transformed into a Lamb wave. In this paper, numerical simulations are performed that show that actually the Schoch effect does occur neither for Rayleigh waves, nor for Lamb waves. As a matter of fact, a pulse, incident at the Rayleigh angle, generates two reflected lobes with a null zone of a different kind. The null zone is beating several times during the passage of each pulse. This results in a 'null zone' having a lower mean intensity than any of the two lobes, still less outspoken than for the case of harmonic incident bounded beams. This effect does only occur for Rayleigh wave generation and is much less outspoken for Lamb wave generation.

Journal Article↗

PubMed1972

Membrane permeability. Generalization of the reflection coefficient method of describing volume and solute flows.

The reflection coefficient method for describing volume and solute fluxes through membranes is generalized to take into account the nonideality of the solutions bathing the membrane and/or multicomponent systems. The reflection coefficient of the impermeable species in these systems is less than unity by a coefficient gamma. The reflection coefficient obtained solely from the volume flow equation, sigma(v), will always be less than the reflection coefficient obtained from the solute flow equation, sigma(8) (v). These two coefficients are related by sigma(8) (v) = sigma(v) + gamma.

Chemical Phenomena↗

PubMed2001

Smaller, stiffer coronary bypass can moderate or reverse the adverse effects of wave reflections.

The question of whether the mechanical stiffness of a coronary bypass or that of a diseased coronary artery can have a significant effect on the hemodynamics in these vessels is addressed analytically, with emphasis on the effects of wave reflections. The analysis is based on a model of the vessels involved, and the results show the essential hemodynamic effects in each vessel. It is found that in the absence of a bypass graft, wave reflections resulting from a narrowing and stiffening of a diseased coronary artery have the effect of actually aiding the flow in the diseased vessel. In the presence of a bypass graft, however, the effects of wave reflections are reversed and become adverse to flow in both the bypass graft and the diseased coronary artery. A stiffer bypass moderates these effects and is therefore preferable to a more elastic bypass. The adverse effects also depend critically on the relative diameter of the bypass. Here the results indicate that a bypass of smaller diameter than that of the native coronary artery can moderate and even reverse the adverse effects of wave reflections resulting from the presence of the bypass.

Anastomosis, Surgical↗

PubMed1999

Effects of wave reflection timing on left ventricular mechanics.

UNLABELLED: The aim of this study was to evaluate how the timing of the pressure pulse produced by peripheral reflection affects the left ventricle (stroke volume, ventricular work, coronary driving pressure). Ten isolated perfused rabbit hearts were attached to rubber tubes of different lengths (0.5, 0.8 and 1 m) connected to a hydraulic resistance. The different lengths produced reflections at different times and the reflected pulse returned to the ventricle in early (at 84 ms), middle (at 134 ms) and late systole (at 168 ms) for the three tubes, respectively. The loading parameters (ventricular filling pressure and hydraulic resistance) were not changed during the procedure. Ventricular and aortic pressure and aortic flow were monitored continuously and recorded; cardiac cycle was fixed at 800 ms. An operator-independent procedure was used to calculate instantaneous and total systolic external work, mean diastolic aorto-ventricular pressure difference and ventricular stroke volume. RESULTS: The mean value of stroke volume for the three different length rubber tubes was 320 +/- 71, 348 +/- 77 and 368 +/- 87 microliters, respectively. The mean value of total external work was 20.3 +/- 8.3, 22.5 +/- 8.8 and 24.2 +/- 9.6 mJ, respectively. The mean aortoventricular pressure difference was 40 +/- 12, 46 +/- 13, 50 +/- 14 mmHg, respectively (1 mmHg = 133 Pa). The differences between the parameters measured in the three conditions were statistically significant (p < 0.05). A reduction of reflection timing, reduces, on a pure mechanical basis, cardiac output and external ventricular work and has a negative effect on coronary driving pressure.

Animals↗