A Markov Chain Monte Carlo approach to the study of massive black hole binary systems with LISA

The Laser Interferometer Space Antenna (LISA) will produce a data stream containing a vast number of overlapping sources: from strong signals generated by the coalescence of massive black hole binary systems to much weaker radiation form sub-stellar mass compact binaries and extreme-mass ratio inspirals. It has been argued that the observation of weak signals could be hampered by the presence of loud ones and that they first need to be removed to allow such observations. Here we consider a different approach in which sources are studied simultaneously within the framework of Bayesian inference. We investigate the simplified case in which the LISA data stream contains radiation from a massive black hole binary system superimposed over a (weaker) quasi-monochromatic waveform generated by a white dwarf binary. We derive the posterior probability density function of the model parameters using an automatic Reversible Jump Markov Chain Monte Carlo algorithm (RJMCMC). We show that the information about the sources and noise are retrieved at the expected level of accuracy without the need of removing the stronger signal. Our analysis suggests that this approach is worth pursuing further and should be considered for the actual analysis of the LISA data.Comment: submitted to cqg as GWDAW-10 conference proceedings, 10 pages, 4 figures, some changes to plots and numerical detail

Nucleation of stable cylinders from a metastable lamellar phase in a diblock copolymer melt

The nucleation of a droplet of stable cylinder phase from a metastable lamellar phase is examined within the single-mode approximation to the mean-field Landau–Brazovskii model for diblock copolymer melts. By employing a variational ansatz for the droplet interfacial profile, an analytic expression for the interfacial free energy of an interface of arbitrary orientation between cylinders and lamellae is found. The interfacial free energy is anisotropic and is lower when the cylinder axis is perpendicular to the interface than when the cylinders lie along the interface. Consequently, the droplet shape computed via the Wulff construction is lens like, being flattened along the axis of the cylinders. The size of the critical droplet and the nucleation barrier are determined within classical nucleation theory. Near the lamellar–cylinder phase boundary, where classical nucleation theory is applicable, critical droplets of size 30–400 cylinders across with aspect ratios of 4–10 and nucleation barriers of (30–40)kBT are typically found. The general trend is to larger critical droplets, higher aspect ratios, and smaller nucleation barriers as the mean-field critical point is approached

UNDERSTANDING FOOD LITERACY AND ITS USE IN A TECHNOLOGY-DRIVEN NUTRITION EDUCATION PROGRAM FOR ADOLESCENTS.

One in three adolescents in the U.S. is overweight or obese. The dietary habits of this population are concerning as few meet current dietary recommendations for consuming fruits and vegetables. Equally troubling among this group is the consumption of sugar-sweetened beverages and the lack of physical activity. Studies that investigate the link between nutrition knowledge, attitudes, and behaviors have shown mixed results and new methods to investigate this relationship are needed. Food literacy is a new term that has risen out of the health and nutrition literacy fields. Food literacy seeks to examine the complex relationship between knowledge, attitudes, and behaviors from the perspective of food and not individual nutrients. Adolescence is a unique life stage when there is development of decision-making skills. Food literacy programs are ideally suited to this stage because the concept focuses on building capacity to operationalize healthy decisions regarding food. New methods are also needed, to help increase engagement and participation in food-related programs. Adolescents are digital natives. Eighty-seven percent have access to a computer, 88% have access to a cellphone, and 92% go online daily, from these devices. Driving the use of cellphones is social media and text messaging. In fact, 91% of adolescents use their cellphone for texting, sending an average of 67 messages/day. Adolescent’s pervasive use of technology, in particular cellphones, provides an opportunity to investigate the potential of this medium to engage participants in education about food. Another novel method to engage adolescents in food-related education is the use of community-based participatory research (CBPR). CBPR is a collaborative approach that includes community members in the research process. The approach incorporates sharing of ideas between community members and researchers, values mutual decision-making, and empowers participants to plan activities and make changes they see as beneficial to their community. CBPR is not often used with adolescents, and no current research has used CBPR to inform a technology-driven, food literacy program for low-income, ethnically diverse adolescents. Filling this gap will add to the understanding of the use of innovative programs and ideas to engage adolescents and help them develop healthy eating behaviors

Stepping away from pharmaceutical therapies: Exercise and supplementation with fermented red clover extract as alternative strategies to promote vascular health in postmenopausal women

Cardiovascular disease is the leading cause of death worldwide. Both aging and menopause, associated with the cessation of endogenous estrogen production, are key factors that contribute to the development of cardiovascular disease in women. Over the last few decades, an interest in alternatives to pharmaceutical interventions for promoting and/or rescuing cardiovascular health in postmenopausal women has emerged, where both exercise and phytoestrogen supplementation have been deemed effective candidates. However, due to the paucity of intervention studies in postmenopausal women, knowledge gaps remain in these strategies that need to be elucidated in the context of vascular health. This dissertation aims to answer three main questions that will refine the scientific community’s understanding of alternative interventions for vascular health in postmenopausal women: (1) Can exercise training work synergistically with in-vitro dual anti-platelet therapy to improve platelet function, as determined by basal platelet reactivity and prostacyclin sensitivity (Chapter 4)? (2) Does the timing of the initiation of exercise training after menopause affect the degree of vascular adaptations and thrombotic risk profile (Chapters 5 and 6)? (3) Can short-term supplementation with the novel phytoestrogen fermented red clover extract improve markers of vascular inflammation (Chapter 7)? Together, the findings from this dissertation highlight that exercise and fermented red clover extract are effective alternative strategies to improving vascular health in postmenopausal women. Specifically, exercise training improves platelet function and sensitivity and can work synergistically with in-vitro dual anti-platelet therapy (Chapter 4). In addition, short-term supplementation with fermented red clover extract improves the vascular inflammatory profile in recently postmenopausal women (Chapter 7). However, the timing of exercise training after menopause may influence the magnitude of thrombogenic adaptations, as recently postmenopausal women experience more robust thrombogenic benefits than women who are a greater number of years postmenopausal (i.e., late postmenopausal women) (Chapter 5 and 6)

Perceptions of Emotions by Simultaneous Bilinguals Across Various Relationship Contexts

Currently, a significant amount of existing research on bilinguals does not distinguish between sequential and simultaneous bilingualism. Furthermore, there is a significant gap in the existing research on simultaneous bilinguals. This exploratory study investigated simultaneous bilinguals’ perceptions of emotional expression in their two first languages, within three relationship contexts: professional, family, romantic partners and friends. A questionnaire was administered to simultaneous bilinguals. According to the findings of this study, simultaneous bilinguals have a preference between one of their first two languages when expressing certain emotions. Additionally, participants report that relationship context impacts the language they select to use when conversing with certain individuals as well as frequency of language use. The findings of this study may have implications in the filed of clinical psychology

LISA Response Function and Parameter Estimation

We investigate the response function of LISA and consider the adequacy of its commonly used approximation in the high-frequency range of the observational band. We concentrate on monochromatic binary systems, such as white dwarf binaries. We find that above a few mHz the approxmation starts becoming increasingly inaccurate. The transfer function introduces additional amplitude and phase modulations in the measured signal that influence parameter estmation and, if not properly accounted for, lead to losses of signal-to-noise ratio.Comment: 4 pages, 2 figures, amaldi 5 conference proceeding

The Microstratigraphy of Two Peat Sequences from Northeastern Newfounland

Commonly, the ombrotrophic peats of Newfoundland have a well-defined banded appearance. Each band consists of a light-coloured lower section and a dark upper component. The bands are separated by abrupt recurrence surfaces. The regularity of the bands implies cyclicity. The physical, elemental, micro- and macro-stratigraphies of two banded profiles from the Wesleyville area were examined in an attempt to document the differences and to provide insight into cause. Ash content, fibre content, bulk density, water content and water retention were measured. The latter three showed consistent changes through each profile. There were no obvious patterns in the values for the biologically active elements that were measured (Mg, Cl, Ca, Na, Al, Mn and I), but the curves for Br, V, and U, biologically inert elements, showed systematic variations that appear to reflect variations in peat accumulation rate. The pollen, spore and macrofossil stratigraphies were generally complacent, although the representation of Sphagnum macrofossils and spores varied regularly as did pollen and spore concentrations. Each light-dark sequence appears to reflect a cycle of self-sustaining hydrologie changes involving changes in community composition, and in oxidation and accumulation rate, rather than climate. The cycles appear to be ca. 700 years in length, and are system-wide, but with variable lag times.Les tourbes ombrothrophes de Terre-Neuve présentent d'ordinaire des couches nettement définies. Chaque couche comporte une partie inférieure claire et une partie supérieure foncée. Les couches sont séparées par des surfaces de récurrence abruptes. La régularité des couches suppose l'existence d'un phénomène cyclique. Les micro et macrostratigraphies physique et celles des éléments de deux coupes de deux profils rubanés de la région de Wesleyville ont été étudiés en vue d'en observer les différences et de déterminer les causes de ces différences. Les teneurs en cendres et en fibres, le poids volumétrique, la teneur en eau et la rétention d'eau ont été mesurés. Les trois dernières propriétés ont montré des changements uniformes dans chacune des coupes. Aucune configuration évidente n'est ressortie des valeurs des éléments biologiquement actifs qui ont été mesurés (Mg, Cl, Ca, Na, Mn et I), mais les courbes de Br, V et U, biologiquement inertes, ont montré des variations systématiques qui semblaient refléter les variations du taux d'accumulation de la tourbe. Les stratigraphies du pollen, des spores et des macrofossiles étaient dans l'ensemble insensibles, bien que la représentation des macrofossiles et des spores de Sphagnum variait de façon régulière, tout comme les concentrations de pollen et de spores. Chacune des séquences claire-foncée semble correspondre à un cycle de changements hydrologiques autogénérateurs impliquant des modifications dans la composition de l'association végétale et dans les taux d'oxydation et d'accumulation, plutôt que dans le climat. Les cycles, qui s'étendent à l'ensemble du système, semblent durer environ 700 ans, mais avec des décalages variables.Im allgemeinen treten die ombrotrophen Torfe Neufundlands in gut erkennbaren Streifen auf. Jeder Streifen besteht aus einer leichtgefàrbten unteren Schicht und einem dunklen oberen Teil. Die Streifen werden durch plôtzlich zu Tage tretende Grenzhorizonte getrennt. Die RegelmâBigkeit der Streifen setzt Periodizitàt voraus. Die Milkro- und Makrostratigraphie des physikalischen und elementaren Aufbaus zweier Streifenprofile aus der Gegend von Wesleyville wurden untersucht, um die Unterschiede aufzuzeichnen und um die Ursachen zu ergrùnden. Gehalt an Asche und Fasern, spezifische Dichte, Wassergehalt und Wasserzurùckhaltungsvermôgen wurden gemessen. Die drei letzteren wiesen konstante Wechsel in jedem Profil auf. Keine deutlichen Muster in den Werten der biologisch aktiven Elemente konnten gemessen werden (Mg, Cl, Ca, Na, Al, Mn und I), aber die kurven von Br, V und U, den biologisch inaktiven Elementen, zeigten systematische Variationen, welche die Variationen von Torfansammlungsraten wiederzuspiegeln schienen. Die Pollen-, Sporen- und makrofossilen Stratigraphien waren im allgemeinen unveràndert, wenn auch das Vorkommen von Sphagnum-Makrofossilen und Sporen genauso wie Pollen- und Sporen- konzentrationen regelmâBige Verànderungen aufwies. Jede helldunkel Sequenz scheint einen Zyklus sich selbsttragender hydrologischer Verâderungen wiederzuspiegeln, die viel mehr Verànderungen in der pflanzlichen Zusammensetzung, der Oxydierung und der Akkumulationsrate zur Folge hatten als klimatische Verànderungen. Die Perioden scheinen etwa 700 Jahre gedauert zu haben, betreffen das ganze System aber mit variablen Verzôgerungen

The Effect of the LISA Response Function on Observations of Monochromatic Sources

The Laser Interferometer Space Antenna (LISA) is expected to provide the largest observational sample of binary systems of faint sub-solar mass compact objects, in particular white-dwarfs, whose radiation is monochromatic over most of the LISA observational window. Current astrophysical estimates suggest that the instrument will be able to resolve about 10000 such systems, with a large fraction of them at frequencies above 3 mHz, where the wavelength of gravitational waves becomes comparable to or shorter than the LISA arm-length. This affects the structure of the so-called LISA transfer function which cannot be treated as constant in this frequency range: it introduces characteristic phase and amplitude modulations that depend on the source location in the sky and the emission frequency. Here we investigate the effect of the LISA transfer function on detection and parameter estimation for monochromatic sources. For signal detection we show that filters constructed by approximating the transfer function as a constant (long wavelength approximation) introduce a negligible loss of signal-to-noise ratio -- the fitting factor always exceeds 0.97 -- for f below 10mHz, therefore in a frequency range where one would actually expect the approximation to fail. For parameter estimation, we conclude that in the range 3mHz to 30mHz the errors associated with parameter measurements differ from about 5% up to a factor of 10 (depending on the actual source parameters and emission frequency) with respect to those computed using the long wavelength approximation.Comment: replacement version with typos correcte