Evolution of the Olympus Mons Caldera, Mars

Extensive high-resolution (15 to 20 m/pixel) coverage of Olympus Mons volcano permits the investigation of the sequence of events associated with the evolution of the nested summit caldera. The sequence of the intra-caldera events is well illustrated by image data collected on orbits 473S and 474S of Viking Orbiter 1. These data cover both the oldest and youngest portions of the caldera floor. The chronology inferred from the observations is presented which in turn can be interpreted in terms of the internal structure of the volcano (i.e., magma chamber depth and the existence of dikes)

Titan solar occultation observations reveal transit spectra of a hazy world

High altitude clouds and hazes are integral to understanding exoplanet observations, and are proposed to explain observed featureless transit spectra. However, it is difficult to make inferences from these data because of the need to disentangle effects of gas absorption from haze extinction. Here, we turn to the quintessential hazy world -- Titan -- to clarify how high altitude hazes influence transit spectra. We use solar occultation observations of Titan's atmosphere from the Visual and Infrared Mapping Spectrometer (VIMS) aboard NASA's Cassini spacecraft to generate transit spectra. Data span 0.88-5 microns at a resolution of 12-18 nm, with uncertainties typically smaller than 1%. Our approach exploits symmetry between occultations and transits, producing transit radius spectra that inherently include the effects of haze multiple scattering, refraction, and gas absorption. We use a simple model of haze extinction to explore how Titan's haze affects its transit spectrum. Our spectra show strong methane absorption features, and weaker features due to other gases. Most importantly, the data demonstrate that high altitude hazes can severely limit the atmospheric depths probed by transit spectra, bounding observations to pressures smaller than 0.1-10 mbar, depending on wavelength. Unlike the usual assumption made when modeling and interpreting transit observations of potentially hazy worlds, the slope set by haze in our spectra is not flat, and creates a variation in transit height whose magnitude is comparable to those from the strongest gaseous absorption features. These findings have important consequences for interpreting future exoplanet observations, including those from NASA's James Webb Space Telescope.Comment: Updated journal reference; data available via http://sites.google.com/site/tdrobinsonscience/science/tita

Teachers as agents of change: An exploration of the concept of teacher agency

The Teacher Agency and Curriculum Change project began in March 2011, and will run until May 2012. The project is conducted at the University of Stirling, in partnership with a Scottish Local Authority. It is funded by the Economic and Social Research Council (ESRC). The research team is:  Dr Mark Priestley (Principal Investigator),  Professor Gert Biesta (Co-Investigator),  Dr Sarah Robinson (Research Fellow). The project comprises a number of in-depth ethnographic case studies in three Scottish schools (primary and secondary). The immediate context for the research is the implementation of Scotland's new Curriculum for Excellence, a policy that aims to change the structure, content and method of Scottish education, and which is an example of modern curricular reform in which teachers are explicitly positioned as agents of change. The project focuses on the ways in which and the extent to which experienced teachers achieve agency in their day to day working contexts, against the background of the introduction of the new curriculum, and on the factors that promote or inhibit such agency. The project has two key aims: to trial a set of methodologies for identifying the factors that impact upon teacher agency, to develop an understanding of key factors that impact upon such agency in contexts of educational change. This paper is one of a series of working papers being produced as part of the research. This, along with other working papers (as they become available) may be downloaded from the project website at http://www.ioe.stir.ac.uk/events/tacc.php

A model for the vertical flux of nitrogen in the upper ocean: Simulating the alteration of isotopic ratios

An idealized, one-dimensional, constant diffusivity mathematical model for the study of the vertical flux of nitrogen in the upper-ocean is presented. We attempt to simulate observed patterns in vertical profiles for the natural abundance of 15N in particulate organic nitrogen (PON) and the concentrations of PON and NO3−. The concentration of phytoplankton nitrogen (II) increased as a result of either increasing the upward flux of NO3−(N) or by increasing the residence time of II. A minimum in the δ15N of phytoplankton nitrogen (δ2) appeared near a maximum in II at the inflection point of the N profile. Increasing the residence time or the vertical eddy diffusivity, reduced the amplitude of the δ2 profile. The model was able to produce reasonably good simulations of observed profiles from two warm-core rings, Rings 82-E and 82-H, using the most appropriate values for the light extinction coefficient and the residence time of PON. These results lend general support to current views regarding the nature and significance of the vertical fluxes of nitrogen in the upper-ocean and hypotheses presented previously concerning the factors which affect the δ15N of PON

Identifying Very Metal-Rich Stars with Low-Resolution Spectra: Finding Planet-Search Targets

We present empirical calibrations that estimate stellar metallicity, effective temperature and surface gravity as a function of Lick/IDS indices. These calibrations have been derived from a training set of 261 stars for which (1) high-precision measurements of [Fe/H], T_eff and log g have been made using spectral-synthesis analysis of HIRES spectra, and (2) Lick indices have also been measured. Our [Fe/H] calibration, which has precision 0.07 dex, has identified a number of bright (V < 9) metal-rich stars which are now being screened for hot Jupiter-type planets. Using the Yonsei-Yale stellar models, we show that the calibrations provide distance estimates accurate to 20% for nearby stars. This paper outlines the second tier of the screening of planet-search targets by the N2K Consortium, a project designed to identify the stars most likely to harbor extrasolar planets. Discoveries by the N2K Consortium include the transiting hot Saturn HD 149026 b (Sato et al. 2005, astro-ph/0507009) and HD 88133 b (Fischer et al. 2005). See Ammons et al. (2005, In Press) for a description of the first tier of N2K metallicity screening, calibrations using broadband photometry.Comment: Accepted for publication in the Astrophysical Journa

INITIAL EXPLORATIONS USING THE KNEE MOMENT VECTOR VERSUS THE KNEE ABDUCTION MOMENT TO IDENTIFY ATHLETES AT RISK OF ACL INJURY

The knee abduction moment (KM-Y) is a biomechanical risk factor for ACL injury, yet multi-planar loads are known to strain the ACL. The KM-Y alone is often used for injury screening and prediction. This study examined if the KM-Y alone would identify athletes with high knee moments. Forty five female participants performed a bilateral drop jump and single leg drop jump with each leg and their 3D motion characteristics and ground reaction forces were measured. The identification of “at risk” individuals was compared between KM-Y, the non-sagittal resultant moment and the resultant knee moment using a risk threshold of the mean+1.6SD. The KM-Y identified 60 and 70% athletes in each task whereas also using the non-sagittal resultant moment identified 90 and 100%. This suggests that transverse plane moments should not be ignored to identify at risk athletes

Athletes’ retirement from elite sport: A qualitative study of parents and partners’ experiences

Objectives Athletes’ experiences of transition out of elite sport have been well documented. Less is known, however, about how the family members of athletes experience the process of transition. This study aimed to gain an in-depth understanding of parents and partners’ experiences and the way that they managed and interpreted their role in the process of transition. Method Individual semi-structured interviews were conducted with the parents and partners (two male and five female) of seven retired elite athletes from the UK. Data were analysed according to the principles of interpretative phenomenological analysis. Results Parents and partners experienced their own transition as they navigated uncertainty and upheaval in their own lives when the athletes retired. Parents and partners had to renegotiate their identity as they adjusted to changing roles and dynamics in their close relationships. Providing support to the former athletes was complicated by parents and partners’ own difficulties during transition and they often felt unsure about their role as a supporter. Parents and partners often experienced difficulties in their relationship with the athletes during their transition, but things improved as time went by. This was due to better communication and a willingness to share their feelings about their experiences. This helped parents and partners to gain a positive perspective on their transition and a sense that their relationship with the athletes had strengthened and grown. Conclusions Transition is often a shared experience and the findings of the present study underline the value of exploring transition at the level of the family or partnership as well as the individual

Athletes' experiences of social support during their transition out of elite sport: An interpretive phenomenological analysis

Objectives The sources and types of social support that athletes receive during the transition out of sport have been well documented. However, less is known about how athletes perceive, mobilise, and manage supportive relationships. This study aimed therefore to gain a more comprehensive insight into the ways that social support may influence how athletes adjust to life following retirement from elite sport. Design The study was designed according to the principles of Interpretative Phenomenological Analysis. Method Eight former British elite athletes (four male and four female) from eight different Olympic sports were recruited using criterion-based purposive sampling strategies. Data collected using semi-structured interviews were analysed to explore subjective experiences of social support during transition. Results Participants' perception of feeling cared for and understood enabled support to be effective. There were variations in participants' ability to seek out and ask for support and those who found this difficult also found transition a more distressing experience. As transitions progressed, the adjustment process was closely linked to the participant's evolving sense of self. New social relationships and social roles fostered a sense of feeling supported, as well as providing opportunities to support others (e.g., other retired athletes). Providing support helped the participants to experience a sense of growth that facilitated adjustment to life after sport. Conclusions The content of support was largely dependent on context; that is, perceptions of supporters were just as important, if not more so, than specific support exchanges. Stigma around asking for help was a barrier to support seeking