Competing Nonadiabatic Relaxation Pathways for Near-UV Excited ortho-Nitrophenol in Aqueous Solution.

Nitrophenols are atmospheric pollutants found in brown carbon aerosols produced by biomass burning. Absorption of solar radiation by these nitrophenols contributes to atmospheric radiative forcing, but quantifying this climate impact requires better understanding of their photochemical pathways. Here, the photochemistry of near-UV (λ = 350 nm) excited ortho-nitrophenol in aqueous solution is investigated using transient absorption spectroscopy and time-resolved infrared spectroscopy over the fs to µs time scale to characterize the excited states, intermediates, and photoproducts. Interpretation of the transient spectroscopy data is supported by quantum chemical calculations using linear-response time-dependent density functional theory (LR-TDDFT). Our results indicate efficient nonradiative decay via an S1(ππ*)/S0 conical intersection leading to hot ground state ortho-nitrophenol which vibrationally cools in solution. A previously unreported minor pathway involves intersystem crossing near an S1(nπ*) minimum, with decay of the resulting triplet ortho-nitrophenol facilitated by deprotonation. These efficient relaxation pathways account for the low quantum yields of photodegradation.

An uneven distribution of strontium in the coccolithophore Scyphosphaera apsteinii revealed by nanoscale X-ray fluorescence tomography.

Coccolithophores are biogeochemically and ecologically important phytoplankton that produce a composite calcium carbonate-based exoskeleton - the coccosphere - comprised of individual platelets, known as coccoliths. Coccoliths are stunning examples of biomineralization; their formation featuring exceptional control over both biomineral chemistry and shape. Understanding how coccoliths are formed requires information about minor element distribution and chemical environment. Here, the first high-resolution 3D synchrotron X-ray fluorescence (XRF) mapping of a coccolith is presented, showing that the lopadoliths of Scyphosphaera apsteinii display stripes of different Sr concentration. The presence of Sr stripes is unaffected by elevated Sr in the culture medium, macro-nutrient concentration, and light intensity, indicating that the observed stripiness is an expression of the fundamental coccolith formation process in this species. Current Sr fractionation models, by contrast, predict an even Sr distribution and will have to be modified to account for this stripiness. Additionally, nano-XANES analyses show that Sr resides in a Ca site in the calcite lattice in both high and low Sr stripes, confirming a central assumption of current Sr fractionation models.

Evaluation of a multi-methods approach to the collection and dissemination of feedback on OSCE performance in dental education.

INTRODUCTION: Feedback is an essential part of the learning process, and students expect their feedback to be personalised, meaningful and timely. Objective Structured Clinical Examination (OSCE) assessments allow examiners to observe students carefully over the course of a number of varied station types, across a number of clinical knowledge and skill domains. They therefore present an ideal opportunity to record detailed feedback which allows students to reflect on and improve their performance. METHODS: This article outlines two methods by which OSCE feedback was collected and then disseminated to undergraduate dental students across 2-year groups in a UK dental school: (i) Individual written feedback comments made by examiners during the examination, (ii) General audio feedback recorded by groups of examiners immediately following the examination. Evaluation of the feedback was sought from students and staff examiners. A multi-methods approach utilising Likert questionnaire items (quantitative) and open-ended feedback questions (qualitative) was used. Data analysis explored student and staff perceptions of the audio and written feedback. RESULTS: A total of 131 students (response rate 68%) and 52 staff examiners (response rate 83%) completed questionnaires. Quantitative data analysis showed that the written and audio formats were reported as a meaningful source of feedback for learning by both students (93% written, 89% audio) and staff (96% written, 92% audio). Qualitative data revealed the complementary nature of both types of feedback. Written feedback gives specific, individual information whilst audio shares general observations and allows students to learn from others. The advantages, limitations and challenges of the feedback methods are discussed, leading to the development of an informed set of implementation guidelines. CONCLUSION: Written and audio feedback methods are valued by students and staff. It is proposed that these may be very easily applied to OSCEs running in other dental schools.

Translational, rotational, and vibrational coupling into phase in diffractively coupled optical cavities.

All-reflective optical systems are under consideration for future gravitational wave detector topologies. A key feature of these all-reflective systems is the use of Fabry-Perot cavities with diffraction gratings as input couplers; however, theory predicts and experiment has shown that translation of the grating surface across the incident laser light will introduce additional phase into the system. This translation can be induced through simple side-to-side motion of the coupler, yaw motion of the coupler around a central point (i.e., rotation about a vertical axis), and even via internal resonances (i.e., vibration) of the optical element. In this Letter we demonstrate on a prototype-scale suspended cavity that conventional cavity length-sensing techniques used to detect longitudinal changes along the cavity axis will also be sensitive to translational, rotational, and vibrational motion of the diffractive input coupler. We also experimentally verify the amplitude response and frequency dependency of the noise coupling as given by theory.

Artificial ears for a biomimetic sonarhead: from multiple reflectors to surfaces.

This work presents an evolutionary approach to pinna design. Narrowband echolocating bats move the pinna to alter the directional sensitivity of their perceptual systems. Adding pinnae to RoBat--a biomimetic sonarhead mounted on a mobile robot--is the goal of this work. After a description of the earlier work on artificial pinnae consisting of multiple reflectors around the transducer, an acoustic model, inspired by a physical model of sound diffraction and reflections in the human concha, is described and revisited as the model to use for evolving complex shapes. A genetic algorithm evolved the shape of the pinnae with respect to desired features of the directivity pattern of the receiver transducers. Some interesting paraboloid shapes for specific echolocating behaviors were evolved, improving performance with respect to the bare transducer's performance.

Cutting edge: integration of human T lymphocyte cytoskeleton by the cytolinker plectin.

Chemokine-induced polarization of lymphocytes involves the rapid collapse of vimentin intermediate filaments (IFs) into an aggregate within the uropod. Little is known about the interactions of lymphocyte vimentin with other cytoskeletal elements. We demonstrate that human peripheral blood T lymphocytes express plectin, an IF-binding, cytoskeletal cross-linking protein. Plectin associates with a complex of structural proteins including vimentin, actin, fodrin, moesin, and lamin B in resting peripheral blood T lymphocytes. During chemokine-induced polarization, plectin redistributes to the uropod associated with vimentin and fodrin; their spatial distribution indicates that this vimentin-plectin-fodrin complex provides a continuous linkage from the nucleus (lamin B) to the cortical cytoskeleton. Overexpression of the plectin IF-binding domain in the T cell line Jurkat induces the perinuclear aggregation of vimentin IFs. Plectin is therefore likely to serve as an important organizer of the lymphocyte cytoskeleton and may regulate changes of lymphocyte cytoarchitecture during polarization and extravasation.

Rigidity of circulating lymphocytes is primarily conferred by vimentin intermediate filaments.

Lymphocytes need rigidity while in circulation, but must abruptly become deformable to undergo transmigration into tissue. Previously, the control of leukocyte deformability has been attributed to microfilaments or microtubules, but the present studies demonstrate the greater importance of vimentin intermediate filaments (IFs). In circulating T lymphocytes, IFs form a distinctive spherical cage that undergoes a rapid condensation into a juxtanuclear aggregate during chemokine-induced polarization. Measurements of the resistance of peripheral blood T lymphocytes to global deformation demonstrate that their rigidity is primarily dependent on intact vimentin filaments. Microtubules, in contrast, are not sufficient to maintain rigidity. Thus, vimentin IFs are a primary source of structural support in circulating human lymphocytes, and their regulated collapse is likely to be an essential element in chemokine-induced transendothelial migration.

Assessing rbf networks using DELVE.

In this paper, different methods for training radial basis function (RBF) networks for regression problems are described and illustrated. Then, using data from the DELVE archive, they are empirically compared with each other and with some other well known methods for machine learning. Each of the RBF methods performs well on at least one DELVE task, but none are as consistent as the best of the other non-RBF methods.

Histopathology of the skin of UV-B irradiated sole (Solea solea) and turbot (Scophthalmus maximus) larvae.

Larval stages of two economically important flatfish, the sole (Solea solea) and turbot (Scophthalmus maximus) were exposed to ambient and elevated levels of UV-B. Sole larvae, which naturally occur in the plankton in early spring, demonstrated skin lesions at elevated levels of UV-B. Histopathology of the sole revealed cellular changes in the integument, characteristic of sunburn damage, with a reduction in the size of mucus-secreting cells and an increased epidermal thickening, especially at the highest doses of UV-B (2.15 KJ bio eff/m2). Pigmentation in the sole is restricted to a few isolated melanocytes. The integrity of the heavily pigmented skin of turbot appeared to be unaffected by comparable doses of UV-B. Both species have protective mechanisms, which minimize the effects of naturally-occurring levels of UV-B. However, sole appear to be poorly adapted to accommodate any further increase in solar radiation.

Combining regression trees and radial basis function networks.

We describe a method for non-parametric regression which combines regression trees with radial basis function networks. The method is similar to that of Kubat, who was first to suggest such a combination, but has some significant improvements. We demonstrate the features of the new method, compare its performance with other methods on DELVE data sets and apply it to a real world problem involving the classification of soybean plants from digital images.

Why do effective smoking prevention programs work? Student changes in social cognitive theory constructs.

Psychosocial smoking prevention programs can decrease adolescent smoking initiation. This study determined if the theoretical variables targeted in a psychosocial smoking prevention program can be improved significantly by participation in a smoking prevention program. The Social Cognitive Theory constructs examined included behavioral capability to resist positive images of smoking, refusal skill-efficacy, total positive refusal expectations and importance, and total negative refusal expectations and importance. The smoking prevention program had a significant impact on student refusal skill-efficacy and total positive refusal expectations and importance. However, the program did not affect behavioral capability to resist positive images of smoking and total negative refusal expectations and importance. Results from the study can be used to improve the impact of psychosocial prevention programs on targeted Social Cognitive Theory constructs and support the continued practice of cigarette refusal strategy role-plays, addressing various types of pressure and emphasizing positive outcomes from cigarette refusals.

A biologically plausible acoustic motion detection neural network.

In this paper we present an acoustic motion detection system to be used in a small mobile robot. While the first purpose of the system has been to be a reliable computational implementation, cheap enough to be built in hardware, effort has also been taken to construct a biologically plausible solution. The motion detector consists of a neural network composed of motion-direction sensitive neurons with a preferred direction and a preferred region of the azimuth. The system was designed to produce a higher response when stimulated by motion in the preferred direction than in the null direction and that is in fact what the system does, which means that, as desired, the system can detect motion and distinguish its direction.

Physical and temporal scaling considerations in a robot model of cricket calling song preference.

Behavioral experiments with crickets show that female crickets respond to male calling songs with syllable rates within a certain bandwidth only. We have made a robot model in which we implement a simple neural controller that is less complex than the controllers traditionally hypothesized for cricket phonotaxis and syllable rate preference. The simple controller, which had been successfully used with a slowed and simplified signal, is here demonstrated to function, using songs with identical parameters to those found in real male cricket song, using an analog electronic model of the peripheral auditory morphology of the female cricket as the sensor. We put the robot under the same experimental conditions as the female crickets, and it responds with phonotaxis to calling songs of real male Gryllus bimaculatus. Further, the robot only responds to songs with syllable rates within a bandwidth similar to the bandwidth found for crickets. By making polar plots of the heading direction of the robot, we obtain behavioral data that can be used in statistical analyses. These analyses show that there are statistically significant differences between the behavioral responses to calling songs with syllable rates within the bandwidth and calling songs with syllable rates outside the bandwidth. This gives the verification that the simple neural control mechanism (together with morphological auditory matched filtering) can account for the syllable rate preference found in female crickets. With our robot system, we can now systematically explore the mechanisms controlling recognition and choice behavior in the female cricket by experimental replication.

A worksite intervention to enhance social cognitive theory constructs to promote exercise adherence.

UNLABELLED: The results suggest social cognitive theory variables associated with the adoption of exercise are changeable in a brief worksite intervention. Self-regulation techniques and outcome-expectancy value improved, but self-efficacy did not improve for the treatment group. One possible explanation is, the intervention did not adequately address the ability to overcome barriers to exercise faced by participants in the intervention. Another explanation may be the effect of experiencing the barriers to exercise faced by subjects during the first 4 weeks of a self-regulated exercise program. Before engaging in exercise, the participants had a perceived level of confidence to overcome barriers to exercise. Once faced with real barriers to exercise, the subjects may have reevaluated their ability to overcome these barriers. It is interesting that the comparison group reported small decreases in all social cognitive theory variables measured in this study. The comparison group received a program of assessment, instruction, and access to facilities that is common to many worksite-based fitness promotion programs. Clearly, this approach did not have a favorable impact on psychosocial variables associated with exercise adherence. These results may be explained by a reevaluation of beliefs and perceived capabilities to exercise, once faced with the real experiences and barriers related to the adoption of an exercise program. The small decreases in social cognitive theory variables in the comparison group may explain high dropout rates in many fitness center programs and warrant further study. IMPLICATIONS: Health promotion specialists at the worksite need intervention programs that are safe, effective, and efficient for their employees. This intervention was based in the classroom, and no exercise was performed during class. This is appealing to employees who do not have access to shower facilities at the worksite. Moreover, in many interventions, subjects exercise during class and have limited time to learn specific skills to help them adopt and maintain exercise outside the structure of the intervention. Having established favorable changes in social cognitive theory constructs attributable to the intervention, a follow-up study should be conducted to determine the extent to which these changes predict adherence to regular exercise. These studies would establish the causal linkages between social cognitive theory constructs and regular exercise. LIMITATIONS: There were specific limitations, and the results should be interpreted cautiously. The sample size was relatively small, although similar to other exercise intervention research reviewed by Dishman. Another limitation of the sample was no random assignment to treatment or comparison group. The results apply only to the subjects who volunteered for this study. The measure of outcome-expectancy value is the most vulnerable of those used to measure outcome expectations and outcome expectancies. It is possible that the results of the study would be substantially altered if a better measure were available. The data were collected through self-administered questionnaires. It was assumed the subjects would provide accurate information, but reliance on self-reported data introduces potential sources of error.

The spectrogram correlation and transformation receiver, revisited.

The spectrogram correlation and transformation (SCAT) receiver has been proposed as a model for the receiver structure used by fm bats. The main contribution of this paper lies in the analysis of which features of the proposed model are responsible for its high accuracy in estimating arrival times of overlapping echoes. Apart from providing an answer to this question, the analysis will also indicate the limitations of the SCAT receiver. In particular, it is shown that the temporal block of the SCAT receiver returns erroneous results for interecho delays < 20 microseconds and for interecho amplitude ratios > 6 dB. It is also shown that the spectral block of the SCAT receiver generates spurious arrival times if more than two overlapping echoes are present. Finally, it is discussed how the characteristic measurement errors predicted by this analysis can be used to further investigate the accuracy of the SCAT receiver as a model of the receiver structure used by fm bats.

One tone, two ears, three dimensions: a robotic investigation of pinnae movements used by rhinolophid and hipposiderid bats.

Bats, which echolocate using broadband calls, are believed to employ the passive acoustic filtering properties of the head and pinnae to provide spectral cues which encode 3-D target angle. Microchiropteran species whose calls consist of a single, constant frequency harmonic (i.e., some species in the families Rhinolophidae and Hipposideridae) may create additional acoustic localization cues via vigorous pinna movements. In this work, two types of echolocation cues generated by moving a pair of receivers aboard a model sensor head are investigated. In the first case, it is supposed that a common 3-D echolocation principle employed by all bats is the creation of alternative viewing perspectives, and that constant frequency (CF) echolocators use pinna movement rather than morphology to alter the acoustic axes of their perceptual systems. Alternatively, it is possible rhinolophids and hipposiderids move their ears to create dynamic cues--in the form of frequency and amplitude modulations--which vary systematically with target elevation. Here the use of binaural and monaural timing cues derived from amplitude modulated echo envelopes are investigated. In this case, pinna mobility provides an echolocator with a mechanism for creating dramatic temporal cues for directional sensing which, unlike interaural timing differences, do not degrade with head size.

From angels to handmaidens: changing constructions of nursing's public image in post-war Britain.

The public image of nursing is an important barometer of how the profession is valued in society. Recent research into images of nurses tends to use content analysis to substantiate claims that the mass media misrepresent the profession, perpetuating outmoded conceptions of nursing work. Such a strategy treats the nature of nursing itself as unproblematic, an object to be more or less accurately 'represented'. But these are assumptions that need to be questioned. The systems of belief and value that produce representations of nursing both reveal and constitute the institutional practices that regulate nursing as a profession, which in turn shape the material form and substance of representational constructs. Drawing on fictional and factual popular and official representations of nursing and nursing work on film, television and in recruitment literature, it is argued that although nursing was consistently constructed as 'women's work' for much of the 20th century, a noticeable shift is perceivable in the status of nursing's public image between the late 1930s and early 1970s.

An improved method for precise control of light exposure at a known circadian time during an animal's subjective night.

The paper describes an electronic device that improves the feedback lighting (LDFB) developed previously. LDFB links environmental lighting conditions to locomotor or other monitored behavior. Subjective Night Light (SNL) has the following advantages over LDFB: it eliminates the multiple transitions between light and dark; it allows for precise control over lighting so that a light signal of variable duration can be phase locked to any phase of the subjective night; it dissociates to a much greater extent any potential cognitive perception of the link between locomotor activity and lighting; and it can be programmed easily. Finally, SNL retains the significant advantage of LDFB in its ability to maintain phase relationship with the endogenous biologic rhythms even in circumstances of phase-shifting or free-running conditions. The SNL system is made from components that can be purchased at most electronics outlets for less than US$100.

Marr's theory of the neocortex as a self-organizing neural network.

Marr's proposal for the functioning of the neocortex (Marr, 1970) is the least known of his various theories for specific neural circuitries. He suggested that the neocortex learns by self-organization to extract the structure from the patterns of activity incident upon it. He proposed a feedforward neural network in which the connections to the output cells (identified with the pyramidal cells of the neocortex) are modified by a mechanism of competitive learning. It was intended that each output cell comes to be selective for the input patterns from a different class and is able to respond to new patterns from the same class that have not been seen before. The learning rule that Marr proposed was underspecified, but a logical extension of the basic idea results in a synaptic learning rule in which the total amount of synaptic strength of the connections from each input ("presynaptic") cell is kept at a constant level. In contrast, conventional competitive learning involves rules of the "postsynaptic" type. The network learns by exploiting the structure that Marr assumed to exist within the ensemble of input patterns. For this case, analysis is possible that extends that carried out by Marr, which was restricted to the binary classification task. This analysis is presented here, together with results from computer simulations of different types of competitive learning mechanisms. The presynaptic mechanism is best known in the computational neuroscience literature. In neural network applications, it may be a more suitable mechanism of competitive learning than those normally considered.

The pattern of respiration with increasing metabolism in a small dasyurid marsupial.

Previous studies have indicated that the pattern of respiration in marsupial and placental mammals may be different. Some marsupials have larger tidal volumes and slower respiratory rates under basal conditions. This study examined the respiratory responses of a small marsupial, Dasyuroides byrnei, to increasing metabolic demand. The highest metabolic rate elicited by cold exposure in a helium-oxygen atmosphere was 10.4 times the basal metabolic rate. Basal tidal volumes and respiratory rates were 138% and 46% respectively of the values predicted for placental mammals. The increasing oxygen demands of metabolism were met by increases in ventilation rather than by changes in oxygen extraction. Initially, tidal volume increased until it reached a maximum value 2.6 times that of basal tidal volume. Subsequently, ventilation was augmented by an increase in respiratory frequency. Ventilatory accommodation to an increasing oxygen demand indicated that D. byrnei has an excellent respiratory capacity to deal with the thermogenic demands of a cold environment.