Master of Science in Human Development and Social Policy

thesisUnited States residents achieve insufficient amounts of physical activity. Insufficient physical activity has been linked to a number of poor health outcomes. Community improvements, such as the provision of a new light rail service as part of a complete street construction project, might encourage more physical activity through active transportation. Past research is divided as to whether active transportation is related to walkability measured objectively by trained raters, or to subjectively perceived walkability, or both. This study uses data from the Moving Across Places Study (MAPS) to assess both objective and subjective walkability in relation to active travel to a complete street across two time points. MAPS is an evaluation of a complete street intervention in which a street received a renovation to serve more than just cars in Salt Lake City, Utah. Participants (N=536) were recruited if they lived within 2 km of the new complete street. Physical activity data were measured objectively with GPS and accelerometer units. Objective and subjective measures of walkability were assessed at both times and across two levels of geographic analysis: neighborhood-wide, and route-specific walkability. Results from data analyses of the data show objective measures of walkability were more strongly related to active transportation on the complete street than subjective measures. Objective measures of aesthetics, pedestrian infrastructure, and pedestrian accessibility were all significantly and negatively associated with active transportation on the complete street. Additionally, neighborhood-wide analyses were better at estimating active transportation on the complete street than route-specific walkability

Ocean acidification affects marine chemical communication by changing structure and function of peptide signalling molecules

Ocean acidification is a global challenge that faces marine organisms in the near future with a predicted rapid drop in pH of up to 0.4 units by the end of this century. Effects of the change in ocean carbon chemistry and pH on the development, growth and fitness of marine animals are well documented. Recent evidence also suggests that a range of chemically mediated behaviours and interactions in marine fish and invertebrates will be affected. Marine animals use chemical cues, for example, to detect predators, for settlement, homing and reproduction. But while effects of high CO₂ conditions on these behaviours are described across many species, little is known about the underlying mechanisms, particularly in invertebrates. Here we investigate the direct influence of future oceanic pH conditions on the structure and function of three peptide signalling molecules with an interdisciplinary combination of methods. NMR spectroscopy and quantum chemical calculations were used to assess the direct molecular influence of pH on the peptide cues and we tested the functionality of the cues in different pH conditions using behavioural bioassays with shore crabs (Carcinus maenas) as a model system. We found that peptide signalling cues are susceptible to protonation in future pH conditions, which will alter their overall charge. We also show that structure and electrostatic properties important for receptor-binding differ significantly between the peptide forms present today and the protonated signalling peptides likely to be dominating in future oceans. The bioassays suggest an impaired functionality of the signalling peptides at low pH. Physiological changes due to high CO₂ conditions were found to play a less significant role in influencing the investigated behaviour. From our results we conclude that the change of charge, structure and consequently function of signalling molecules presents one possible mechanism to explain altered behaviour under future oceanic pH conditions

Accounting Hall of Fame 1998 induction: Arthur Ramer Wyatt

For Arthur Ramer Wyatt\u27s Induction, there were: Remarks by Donald E. Kieso, Northern Illinois University; Remarks by Jerry J. Weygandt, University of Wisconsin; Citation written by Daniel L. Jensen, The Ohio State University read by Donald E. Kieso and Jerry J. Weygandt; Response by Arthur R. Wyatt, Arthur Andersen & Co., retired, and University of Illinois

Systematic calculation of molecular vibrational spectra through a complete Morse expansion

We propose an accurate and efficient method to compute vibrational spectra of molecules, based on exact diagonalization of an algebraically calculated matrix based on powers of Morse coordinate. The present work focuses on the 1D potential of diatomic molecules: as typical examples, we apply this method to the standard Lennard-Jones oscillator, and to the ab initio potential of the H2 molecule. Global cm-1 accuracy is exhibited through the H2 spectrum, obtained through the diagonalization of a 30 x 30 matrix. This theory is at the root of a new method to obtain globally accurate vibrational spectral data in the context of the multi-dimensional potential of polyatomic molecules, at an affordable computational cost.Comment: 30 pages including 6 figure

Thresholds for Activation of Rabbit Retinal Ganglion Cells with an Ultrafine, Extracellular Microelectrode

PURPOSE. To determine electrical thresholds required for extracellular activation of retinal ganglion cells as part of a project to develop an epiretinal prosthesis. METHODS. Retinal ganglion cells were recorded extracellularly in retinas isolated from adult New Zealand White rabbits. Electrical current pulses of 100-s duration were delivered to the inner surface of the retina from a 5-m long electrode. In about half of the cells, the point of lowest threshold was found by searching with anodal current pulses; in the other cells, cathodal current pulses were used. RESULTS. Threshold measurements were obtained near the cell bodies of 20 ganglion cells and near the axons of 19 ganglion cells. Both cathodal and anodal stimuli evoked a neural response in the ganglion cells that consisted of a single action potential of near-constant latency that persisted when retinal synaptic transmission was blocked with cadmium chloride. For cell bodies, but not axons, thresholds for both cathodal and anodal stimulation were dependent on the search method used to find the point of lowest threshold. With search and stimulation of matching polarity, cathodal stimuli evoked a ganglion cell response at lower currents (approximately one seventh to one tenth axonal threshold) than did anodal stimuli for both cell bodies and axons. With cathodal search and stimulation, cell body median thresholds were somewhat lower (approximately one half) than the axonal median thresholds. With anodal search and stimulation, cell body median thresholds were approximately the same as axonal median thresholds. CONCLUSIONS. The results suggest that cathodal stimulation should produce lower thresholds, more localized stimulation, and somewhat better selectivity for cell bodies over axons than would anodal stimulation. (Invest Ophthalmol Vis Sci. 2003; 44:3533-3543) DOI:10.1167/iovs.02-1041 O ur ultimate goal is to develop an implantable retinal prosthesis that electrically stimulates the retina to provide some functional vision to patients with advanced retinitis pigmentosa or age-related macular degeneration. Retinitis pigmentosa and age-related macular degeneration are forms of blindness that result in substantial loss of photoreceptors. Although physiological and morphologic changes may take place in the inner retinas of affected patients, 1-5 the opportunity exists for direct electrical excitation of the residual neurons as a means of restoring vision. Stimulation possibilities are either epiretinal (the stimulating points are on the inner surface of the retina) or subretinal (the stimulating points are on the outer surface of the retina, between the neural retina and the underlying pigment epithelium). The goal of the present study was to determine current threshold and increase in threshold with electrode displacement for epiretinal stimulation of retinal ganglion cells. The former can be used to judge the power requirements of a functioning prosthesis and the potential for electrochemical toxicity that occurs as current passes through the metal electrode. The latter can be used to guide the choice of interelectrode spacing and estimate the potential spatial resolution that could be derived from a prosthesis. Another motivation is the desire to achieve selective stimulation of ganglion cell bodies rather than axons en passage, which would presumably enhance the quality of perceptions induced by a retinal prosthesis. Only a few studies 6 -8 have been reported in which the currents needed to stimulate individual ganglion cells in the retina with an epiretinal electrode were investigated, and in none of these studies was the current thresholds of axons compared with cell bodies or the current thresholds measured as a function of electrode distance from the site of activation. Also, with the exception of Grumet et al., 8 relatively large microelectrodes have been used in these studies. A small microelectrode was used in the present study to enable a more precise study of threshold variation with electrode position near a cell body or axon of a ganglion cell. Preliminary portions of this work have been presented elsewhere 9 (Wyatt JL, et al. IOVS 1994;35:ARVO Abstract 593; Rizzo JF, et al. IOVS 1997;38:ARVO Abstract 182). MATERIALS AND METHODS Thirty-two adult New Zealand White rabbits (2-2.5 kg) were used in this study. All experimental procedures were in accordance with institutional guidelines and conformed to the guidelines of the ARVO Statement for the Use of Animals in Ophthalmic and Vision Research. Retinal Preparation The rabbits were sedated by an intraperitoneal injection of urethane (1.6 g/kg) and then received an intravenous injection of pentobarbital sodium (20 mg/kg) for deep anesthesia. Under normal room lighting, an eye was enucleated and hemisected, and the vitreous humor was removed with gentle suction applied to the back of a Pasteur pipet. A strip (Ϸ1 ϫ 2 cm) of inferior retina and attached sclera including the optic nerve head was removed and laid flat, ganglion cell side up, on a 10°inclined platform. The retinal strip was superfused with a solution of 8.9 g/L Ames medium (Sigma-Aldrich, St. Louis, MO), 1.9 g/L NaHCO 3 , and 0.8 g/L D-glucose and saturated with 95% O 2 -5% CO 2 . The solution flowed by gravity over the surface of the retina at a rate of 1.4 to 1.7 mL/min. The temperature of the solution on the retina was maintained at 34°C to 36°C. Diffuse background light (Ϸ1 W/cm 2 at the retina) was present throughout the experiments

Child Psychosocial Adjustment and Parenting in Families Affected by Maternal HIV/AIDS

Child adjustment and parenting were examined in 23 9-through 16-year-old youth from families affected by maternal HIV infection and 20 same-age peers whose mothers were not infected. Children whose mothers were seropositive reported significantly more externalizing problems. Infected mothers reported less age-appropriate supervision/monitoring relative to non-infected mothers. Better mother-child relationship quality and less impairment in parental supervision/monitoring of age-appropriate youth behaviors were associated with fewer externalizing difficulties among the HIV-positive group only. Similarly, only among HIV-infected mothers was refraining from engaging in inconsistent disciplinary tactics associated with lower reports of internalizing and externalizing problems. These data highlight the promise of programs targeting parenting skills to prevent or ameliorate child difficulties

Geometrical and Physical Properties of Circumbinary Discs in Eccentric Stellar Binaries

In a previous work (Pichardo et al. 2005), we studied stable configurations for circumstellar discs in eccentric binary systems. We searched for "invariant loops": closed curves (analogous to stable periodic orbits in time-independent potentials) that change shape with the binary orbital phase, as test particles in them move under the influence of the binary potential. This approach allows us to identify stable configurations when pressure forces are unimportant, and dissipation acts only to prevent gas clouds from colliding with one another. We now extend this work to study the main geometrical properties of circumbinary discs. We have studied more than 100 cases with a range in eccentricity 0 .le. e .le. 0.9, and mass ratio 0.1 .le. q .le. 0.9. Although gas dynamics may impose further restrictions, our study sets lower stable bounds for the size of the central hole in a simple and computationally cheap way, with a relation that depends on the eccentricity and mass ratio of the central binary. We extend our previous studies and focus on an important component of these systems: circumbinary discs. The radii for stable orbits that can host gas in circumbinary discs are sharply constrained as a function of the binary's eccentricity. The circumbinary disc configurations are almost circular, with eccentricity e_d < 0.15, but if the mass ratio is unequal the disk is offset from the center of mass of the system. We compare our results with other models, and with observations of specific systems like GG Tauri A, UY Aurigae, HD 98800 B, and Fomalhaut, restricting the plausible parameters for the binary.Comment: 12 pages, 10 figures and 6 tables. MNRAS, accepte

SCUBA Observations of Dust around Lindroos Stars: Evidence for a Substantial Submillimetre Disc Population

We have observed 22 Lindroos stars with SCUBA on the JCMT to search for evidence of dust discs. Stars in this sample are the less massive companions of B-type primaries and have ages of 10-170Myr. Dust was detected around three of these stars (HD74067, HD112412 and HD99803B). The emission around HD74067 is centrally peaked and is approximately symmetrically distributed out to ~70". This emission either arises from a two component disc, one circumstellar and the other circumbinary with dust masses of 0.3 and >27Mearth respectively, or an unrelated background object. The other two detections we attribute to circumsecondary discs with masses of 0.04 and 0.3Mearth; a circumprimary disc is also present around HD112413 with a similar mass to that around the companion HD112412. Cross-correlation of our sample with the IRAS catalogs only showed evidence for dust emission at 25um and 60um toward one star (HD1438); none of the sub-mm detections were evident in the far-IR data implying that these discs are cold (<40K assuming beta=1). Our sub-mm detections are some of the first of dust discs surrounding evolved stars that were not detected by IRAS or ISO and imply that 9-14% of stars could harbour previously undetected dust discs that await discovery in unbiased sub-mm surveys. If these discs are protoplanetary remnants, rather than secondary debris discs, dust lifetime arguments show that they must be devoid of small <0.1mm grains. Thus it may be possible to determine the origin of these discs from their spectral energy distributions. The low dust masses for this sample support the picture that protoplanetary dust discs are depleted to the levels of the brightest debris discs (~1Mearth) within 10Myr.Comment: 14 pages, 4 figures, accepted by MNRA

Vertebrate pheromones and other semiochemicals: the potential for accommodating complexity in signalling by volatile compounds for vertebrate management

The interaction between volatile and non-volatile, e.g. proteinaceous, components of pheromone and other semiochemical-based signalling systems presents a daunting set of problems for exploitation in the management of vertebrates, good or bad. Aggravating this is the complexity of the mixtures involved with pheromones, not only by definition associated with each species, but also with individual members of that species and their positions within their immediate communities. Nonetheless, already in some contexts, particularly where signals are perceived at other trophic levels from those of the vertebrates, e.g. by arthropods, reductionist approaches can be applied whereby the integrity of complex volatile mixtures is maintained, but perturbed by augmentation with individual components. In the present article, this is illustrated for cattle husbandry, fish farming and human health. So far, crude formulations have been used to imitate volatile semiochemical interactions with non-volatile components, but new approaches must be developed to accommodate more sophisticated interactions and not least the activities of the non-volatile, particularly proteinaceous components, currently being deduced

Mid-IR observations of circumstellar disks -- Part III: A mixed sample of PMS stars and Vega-type objects

We present new mid-infrared spectra for a sample of 15 targets (1 FU Orionis object, 4 Herbig Ae stars, 5 T Tauri stars and 5 Vega type stars), obtained with the TIMMI2 camera at La Silla Observatory (ESO). Three targets are members of the beta Pic moving group (HD 155555, HD 181296 and HD 319139). PAH bands are observed towards the T Tauri star HD 34700 and the Herbig Ae star PDS 144 N. For HD 34700, the band profiles indicate processed PAHs. The spectrum of the Vega-type object eta Corvi (HD 109085), for which a resolved disk at sub-mm wavelengths is known, is entirely stellar between 8--13 micron. Similarly, no indication for circumstellar matter at mid-infrared wavelengths is found towards the Vega-like stars HD 3003, HD 80951, HD 181296 and, surprisingly, the T Tauri system HD 155555. The silicate emission features of the remaining eight sources are modelled with a mixture of silicates of different grain sizes and composition. Unprocessed dust dominates FU Ori, HD 143006 and CD-43 344. Large amorphous grains are the main dust component around HD 190073, HD 319139, KK Oph and PDS 144 S. Both small grains and crystalline dust is found for the Vega-type HD 123356, with a dominance of small amorphous grains. We show that the infrared emission of the binary HD 123356 is dominated by its late-type secondary, but optical spectroscopy is still required to confirm the age of the system and the spectral class of the companion. For most targets this is their first mid-infrared spectroscopic observation. We investigate trends between stellar, disk and silicate properties and confirm correlations of previous studies. Several objects present an exciting potential for follow-up high-resolution disk studies.Comment: Accepted for publication in A&