Alternative interventions for young men's mental health

The main aim of this thesis was to explore the effectiveness and acceptability of alternative interventions for facilitating help-seeking and improving the mental health of young adult males. Based on recommendations for innovative ways to develop interventions that facilitate mental health help-seeking specific to men (Addis & Mahalik, 2003), the interventions employed in this thesis integrate exercise and psychotherapeutic strategies, and make use of sport as a vehicle for mental health promotion. Findings from the Randomised Controlled Trial (RCT) comprising study 1 provided support for a team-sport/psychosocial intervention (Back of the Net; BTN programme) for improving depressive symptoms among men. Employing qualitative methodology, study 2 explored men’s perceptions and experiences of receipt, implementation and acceptability of the BTN programme. Findings from this process evaluation reported positively on the use of sport as a vehicle for accessing and engaging men in a mental health intervention. The RCT employed in study 3 found that the combined strategies of exercise and a sports-based psychotherapeutic intervention delivered via the internet were not beneficial for mental health beyond the effects of exercise alone. Thus, the studies comprising this thesis further provide both quantitative and qualitative evidence in support of the effectiveness of exercise for improving mental health. With respect to the therapeutic processes that may mediate the antidepressant effect of exercise, study 4 reports on exercise self-efficacy, physical self-concept and global self-esteem as potential mechanisms of change. Temporal findings from study 4 suggest that these psychosocial mechanisms may be important factors associated with the effect of exercise on depression. Overall, the findings from this thesis advance our understanding of the effectiveness and acceptability of exercise and CBT-based interventions delivered within the context of sport for young men’s mental health

Determining the context and scale at which functional traits increase Nicotiana attenuata yields

At least 10,000 years ago, humans began domesticating crop plants into consistent, high-yielding food sources. Plants continue to provide 90% of human food energy intake worldwide. However, as human populations increase and arable land becomes scarce or unproductive due to climate instability, plant food sources may no longer be able to sustain human nutritional requirements. Plant populations must become more productive. This dissertation uses an ecological model plant, Nicotiana attenuata, to evaluate the contexts and scales at which plant populations can increase their productivity. I explore the current uses and future potentials of three functional traits that can be selected for, or genetically modified, in crop cultivars to improve agricultural yields. First, I test the efficacy of current agricultural pest-resistance technology in increasing yield. The pest-resistance technology (Cry1Ac expression), conferred through genetic modification to N. attenuata, did not increase yield in comparison to endogenously defended, or even undefended N. attenuata lines. Due to the scarcity of Cry1Ac-targeted insects in this field season, plants with more flexible use of their direct defenses were able to be more productive, demonstrating the benefit of naturally evolved defenses in the face of yearly-inconsistent pests. Resource-use traits such as plant water-use or association with arbuscular mycorrhizal fungal (AM) networks that facilitate nutrient access are as important to agricultural productivity as pest-resistance. Current screenings for water-use traits among agricultural varieties are insufficient: they do not account for varying rates of soil water consumption or plant development in applying drought treatments, and therefore, do not lead to reproducible results in the field. We use variance decomposition to quantify the extent to which these factors, when left uncontrolled, can significantly change observed results. I then apply the ecologically established biodiversity-productivity phenomenon to attempt to increase population yields by varying the percentage of plants with a low water-use efficiency trait among control plants in N. attenuata field populations. Low percentages of this trait caused overyielding. Using both novel and developed methodologies, I advance the understanding of the mechanisms behind this effect by identifying one of its genetic bases, and narrowing the spatial scale and plant tissue at which it occurs. Finally, we develop a method for screening agricultural cultivars for association with AM fungal networks by using a high-throughput leaf molecular marker rather than traditional microscopy methods, which are laborious and destructive. This work emphasizes the benefits of methodological development, which can both improve screenings for agriculturally-relevant functional traits and allow for application of ecologically-informed alternatives to increase population yield (e.g. intraspecific diversity).Bereits vor mindestens 10 000 Jahren begannen Menschen Pflanzen zu domestizieren und gewannen damit einheitliche und ertragreiche Nahrungsquellen. Auch heute nehmen Menschen 90% ihrer Nahrungsenergie über Pflanzen auf. Allerdings könnten in Zukunft Pflanzen nicht ausreichen, um die menschlichen Nahrungsbedürfnisse zu decken. Die Weltbevölkerung wächst und Klimainstabilität führt zu schrumpfenden Agrarflächen oder sinkenden Erträgen. Pflanzen müssen dementsprechend ertragreicher werden. In dieser Dissertation wird die Modellpflanze Nicotiana attenuata verwendet, um die Zusammenhänge und Ausmaße zu erforschen, in denen Pflanzenpopulationen ihre Leistungsfähigkeit steigern können. Ich untersuche die derzeitige Anwendung sowie zukünftige Potentiale von drei funktionellen Eigenschaften, die in der Züchtung selektiert oder in Pflanzen genetisch modifiziert werden können, um landwirtschaftliche Erträge zu steigern. Zuerst analysiere ich, wie effizient derzeitige landwirtschaftliche Schädlingsresistenztechnologien die Ausbeute erhöhen. Die Expression des Cry1Ac als Verteidigungssystem, eingebracht in N. attenuata durch genetische Modifikation, führte zu keiner Ertragssteigerung im Vergleich zu Pflanzen mit endogener Verteidigung oder sogar unverteidigten N. attenuata-Linien. Da in der Saison des Feldversuchs nur wenige Insekten vorkamen, gegen die das Cry1Ac-System gerichtet ist, reagierten Pflanzen mit endogener Verteidigung plastischer und damit produktiver auf ganzjährlich variierende Herbivorgemeinschaften. Genauso wichtig wie Schädlingsresistenz sind die Ressourcennutzung sowie die Assoziation mit arbuskulären Mykorrhizapilzen (AM-Pilzen), die den Zugang zu Nährstoffen unterstützen. Derzeitige Untersuchungen zu Wassernutzungseigenschaften verschiedener Agrarsorten sind unzureichend: In Versuchen mit Dürrebehandlung werden Unterschiede im Bodenwasserverbrauch oder die Entwicklung der Pflanzen nicht berücksichtigt und führen dementsprechend nicht zu reproduzierbaren Ergebnissen im Feld. Durch Varianzzerlegung quantifizieren wir, in welchem Ausmaß die einzelnen Faktoren, sollten sie unkontrolliert bleiben, die Ergebnisse signifikant verändern können. Mithilfe des ökologisch etablierten Biodiversitäts-Produktivitäts-Phänomens habe ich versucht die Populationserträge zu erhöhen, indem ich die Anteile von Pflanzen mit geringer Wasserverbrauchseffizienz und Kontrollpflanzen variiert habe. Waren solche Pflanzen zu einem geringen Prozentsatz in N. attenuata Feldpopulationen vorhanden, führte dies zu einer Ertragssteigerung. Mittels sowohl neuer als auch etablierter Methoden ist es mir gelungen zum Verständnis der Mechanismen hinter diesem Effekt beizutragen, indem ich eine der zugrundeliegenden genetischen Ursachen identifiziert habe und das räumliche Ausmaß sowie das Pflanzengewebe, in dem dieser Effekt auftritt, eingegrenzt habe. Abschließend entwickelten wir eine Methode, um Kultivare in Agrarpopulationen auf Assoziation mit AM-Pilzen zu untersuchen, bei der im high-throughput-Verfahren ein molekularer Marker im Blatt statt der traditionellen, aufwendigen und schädlichen Mikroskopiemethode verwendet wurde. Diese Arbeit betont die Vorteile von Methodenentwicklung, welche sowohl die Suche nach landwirtschaftlich relevanten Eigenschaften verbessern kann als auch die Anwendung von ökologisch begründeten Alternativen zur Ertragssteigerung ermöglicht (z.B. intraspezifische Diversität)

Photopolarimetric Analysis of Early-Type Stars

Over the past few years it has been shown that some (single) early-type stars display polarimetric variability, with the data distributed in the normalized Stokes plane above the usual experimental noise. Presently, in this thesis, a simple point source/point scattering model is developed, which can mimic these distributions. It is found that they should always exhibit at least one axis of symmetry, this being the projection of the stellar equatorial plane onto the sky. In addition the model is extended to involve the effects of stellar rotation and schemes are proposed for investigating the underlying loci in the distributions which lead to determination of stellar periods

A ROSAT Survey of Contact Binary Stars

Contact binary stars are common variable stars which are all believed to emit relatively large fluxes of x-rays. In this work we combine a large new sample of contact binary stars derived from the ROTSE-I telescope with x-ray data from the ROSAT All-Sky Survey (RASS) to estimate the x-ray volume emissivity of contact binary stars in the galaxy. We obtained x-ray fluxes for 140 contact binaries from the RASS, as well as 2 additional stars observed by the XMM-Newton observatory. From these data we confirm the emission of x-rays from all contact binary systems, with typical luminosities of approximately 1.0 x 10^30 erg s^-1. Combining calculated luminosities with an estimated contact binary space density, we find that contact binaries do not have strong enough x-ray emission to account for a significant portion of the galactic x-ray background.Comment: 19 pages, 5 figures, accepted by A

Biomechanical analysis of Total Knee Arthroplasty performed on a 6 degree of freedom joint motion simulator linked to a virtual ligament model in mechanical and kinematic alignments

Total knee arthroplasty (TKA) is a very successful surgery providing many patients with increased quality of life. Despite this, some patients are dissatisfied. There are also complications with total knee arthroplasty that lead to the need for revision surgery. Improvements in stability, soft tissue balance, joint kinematics and overall patient satisfaction may lead to a decrease in TKA revisions. It is still unclear what the optimal soft tissue tension, balance or alignment is to provide superior patient outcomes. Computational models provide a means to effectively parameterize ligaments and simulate multiple scenarios of TKA. This work implemented a sophisticated 6-degree of freedom joint motion simulator merged with a virtual soft tissue model, eliciting the soft-tissues properties used to balance TKAs. Through testing joint kinematics and soft tissue laxity through 90° of neutral flexion and extension and simulated Activities of Daily Living (ADLs) we were able to reproduce a model that elicited joint kinematics in a balanced TKA similar to what has been shown in the literature. We also compared mechanically aligned (MA) and kinematically aligned (KA) TKAs. This work offers a baseline computational model that reproduces appropriate TKA joint kinematics and laxities, which can then be used for future studies providing better understanding of total knee arthroplasty

Lung cancer deaths from indoor radon and the cost effectiveness and potential of policies to reduce them

Objective To determine the number of deaths from lung cancer related to radon in the home and to explore the cost effectiveness of alternative policies to control indoor radon and their potential to reduce lung cancer mortality

X-ray Doppler Imaging of 44i Boo with Chandra

Chandra High-Energy Transmission Grating observations of the bright eclipsing contact binary 44i Boo show X-ray line profiles which are Doppler-shifted by orbital motions. The X-ray emission spectrum contains a multitude of lines superimposed on a weak continuum, with strong lines of O VIII, Ne X, Fe XVII, and Mg XII. The profiles of these lines from the total observed spectrum show Doppler-broadened widths of ~ 550 km s^{-1}. Line centroids vary with orbital phase, indicating velocity changes of > 180 km s^{-1}. The first-order light curve shows significant variability, but no clear evidence for either primary or secondary eclipses. Flares are observed for all spectral ranges; additionally, the light curve constructed near the peak of the emission measure distribution (T_e = 5 to 8 X 10^6 K) shows quiescent variability as well as flares. The phase-dependences of line profiles and light curves together imply that at least half of the emission is localized at high latitude. A simple model with two regions on the primary star at relatively high latitude reproduces the observed line profile shifts and quiescent light curve. These first clear X-ray Doppler shifts of stellar coronal material illustrate the power of Chandra.Comment: 15 pages, 6 figures to be published in Astrophysical Journal Letter

The influence of front‐of‐pack portion size images on children's serving and intake of cereal

Background: Consumption of large portions of energy‐dense foods promotes weight gain in children. Breakfast cereal boxes often show portions much larger than the recommended serving size. Objective: This experimental study investigated whether front‐of‐package portion size depictions influence children's self‐served portions and consumption. Methods: In a between‐subjects design, 41 children aged 7‐11 years (M= 9.0 ± 1.5y) served themselves breakfast cereal from a box, the front of which depicted either a recommended serving size of cereal (30g) or a larger, more typical front‐of‐ pack portion (90g). Cereal served and consumed and total caloric intake (including milk) was recorded. Height and weight, demographic information and measures of children's food responsiveness and enjoyment of food were collected. Results: MANOVA revealed that children exposed to the larger portion size served themselves (+7g, 37%) and consumed (+6g, 63%) significantly more cereal than those exposed to the smaller portion. Despite this, overall caloric intake (milk included) did not differ between conditions, and no other measured variables (hunger, BMI) significantly affected the outcomes. Conclusion: This study provides novel evidence of the influence portion‐size depictions on food packaging have on children's eating behaviour. This offers possible avenues for intervention and policy change; however, more research is needed