6,257 research outputs found
The Galactic Isotropic -ray Background and Implications for Dark Matter
Full text linkWe present an analysis of the radial angular profile of the galacto-isotropic
(GI) -ray flux--the statistically uniform flux in circular annuli about
the Galactic center. Two different approaches are used to measure the GI flux
profile in 85 months of Fermi-LAT data: the BDS statistic method which
identifies spatial correlations, and a new Poisson ordered-pixel method which
identifies non-Poisson contributions. Both methods produce similar GI flux
profiles. The GI flux profile is well-described by an existing model of
bremsstrahlung, production, inverse Compton scattering, and the
isotropic background. Discrepancies with data in our full-sky model are not
present in the GI component, and are therefore due to mis-modeling of the
non-GI emission. Dark matter annihilation constraints based solely on the
observed GI profile are close to the thermal WIMP cross section below 100 GeV,
for fixed models of the dark matter density profile and astrophysical
-ray foregrounds. Refined measurements of the GI profile are expected
to improve these constraints by a factor of a few.Comment: 20 pages, 15 figures, references adde
Hook-content formulae for symplectic and orthogonal tableaux
Full text linkBy considering the specialisation of the
Schur function, Stanley was able to describe a formula for the number of
semistandard Young tableaux of shape in terms of two properties of
the boxes in the diagram for . Using specialisations of symplectic and
orthogonal Schur functions, we derive corresponding formulae, first given by El
Samra and King, for the number of semistandard symplectic and orthogonal
-tableaux.Comment: Withdrawn; paper is outdate
Effects of growth and fixed mindset on leaders\u27 behavior during interpersonal interactions
Get PDFGrowth mindset, the belief that traits are changeable, is a concept that has impacted the field of education and has recently gained a foothold in the world of business. This mixed methods study sought to better understand how high-level leaders’ internal growth or fixed mindsets affect their behavior in interpersonal interactions with others. 12 directors and vice presidents participated in a self-assessment and interviews to ascertain their general mindsets in five domains and their experience of workplace interactions. The study found that leaders’ mindsets affect their interactions with others. The study also found that leaders who scored as having growth mindset may still experience episodes of situational fixed mindset that may detract from their effectiveness
Sperm pHertility: male gamete responses to ocean acidification and other stressors
Get PDFOcean acidification (OA) together with other anthropogenic perturbations is projected to dramatically alter marine environments over the coming centuries. The vast majority of marine species reproduce by freely spawning sperm directly into the water column, where fertilisation can then either be external or a female can draw sperm into a burrow, brooding chamber or onto her external surface. Hence, sperm are now being released into rapidly changing seawater conditions. In this thesis, I firstly assess what is currently known on the potential for OA and other anthropogenic stressors to influence freely spawned sperm in marine invertebrate taxa. I then present a series of experimental chapters investigating the influence of OA, as a single stressor or in conjunction with a second stressor, copper, on sperm function, physiology and competitive fertilisation performance in a range of invertebrate taxa.
My research demonstrates that sperm are vulnerable to the projected changes in seawater carbonate chemistry under OA, with responses observed at all biological levels from sperm physiology, swimming performance, fertilisation ecology and sperm competitiveness. In a multi-stressor experiment on polychaete gametes and larvae, I provide empirical evidence that changes to seawater pH under OA can alter the susceptibility of early life stages including sperm, to the common coastal pollutant copper. Sperm DNA damage increased by 150 % and larval survivorship was reduced by 44 % in combined exposures, than when exposed to copper alone. As a single stressor OA also acted to significantly reduce Arenicola marina sperm swimming speeds and fertilisation success. This work was followed up with a mechanistic investigation of A. marina sperm swimming performance under OA conditions. I found that the length of time between spawning and fertilisation can strongly influence the impact of OA on sperm performance. Key fitness-related aspects of sperm functioning declined after several hours under OA conditions, and these declines could not be explained by changes in sperm ATP content, oxygen consumption or viability.
In a final set of experiments, I ran a set of paired competitive fertilisation trials in the sea urchin, Paracentrotus lividus. In addition to reducing fundamental sperm performance parameters, OA conditions affected competitive interactions between males during fertilisation, with potential implications for the proportion of offspring contributed by each male under the new conditions. This work suggests that the ‘best’ males currently may not be the most competitive under OA. Overall this body of work reveals a series of significant changes to sperm performance under OA that might act to perturb sperm functioning in future oceans.NER
A Hermeneutic Phenomenological Study of Surgical Technology Graduates Who Achieved Transformative Learning
Get PDFThe purpose of this hermeneutic phenomenological study was to understand the experiences of successful surgical technology graduates who achieved transformative learning during their CAAHEP accredited surgical technology program while encountering risk factors for failure. The study’s central research question is: What experiences of successful surgical technology graduates contributed to transformative learning? The theory guiding this study is Mezirow’s (1981) theory of transformative learning. Mezirow’s theory relates to this study as it requires individuals to find meaning in learning in order, through a disorienting dilemma, to acquire new perspectives on their subject matter. The setting of this study is Commission on Accreditation of Allied Health Education Programs (CAAHEP) accredited surgical technology programs throughout the country. Purposeful criterion sampling assures the identification and selection of information-rich participants who experienced the phenomenon. The data collection for this study includes surveys, interviews, and letters written by successful surgical technology graduates. Data collection and analysis occur through the continued reading of surveys, interviews, and letters which capture the essence of each student’s experience through detailed written descriptions
The Environmental Audit Privilege: Where Does Louisiana Stand in the Federal v. State Showdown?
Get PDFDoes incidental mean indiscriminate? a study of incidental news consumption's effect on processing of claims in health news
Get PDFSince the 2016 election, fake news has taken center stage in the American news landscape. The risk of fake news being widely disseminated and widely believed is a great fear for many, and this study addresses factors associated with our tendencies in consuming fake news. Specifically, this study asks how incidental news consumption affects a person's news discernment. Prior research suggests that people may consume news "incidentally" or accidentally online, and the context in which they are viewing news may alter their ability to critically understand and engage with it. A lack of conscious intent in a user's news consumption can have negative consequences, such as a lack of political participation and poor media literacy. Therefore, this study attempts to understand how news habits are associated with a person's ability to discern between true and false claims in health news. To do so, this study hypothesizes that incidental news exposure is negatively associated with news media discernment, or in other words, people who mostly consume news incidentally are not equipped to discern between real and fake news. The results showed, in line with the hypothesis, that incidental, or passive, news consumers were more likely to view fake news as more accurate and less biased than their active news consumer counterparts, and less likely to view real news as accurate and unbiased than their active news consumer counterparts, suggesting that active news consumers are more discerning
Academic careers: a cross-country perspective
Full text linkAsymmetric international mobility of highly talented scientists is well documented. We try contributing to the explanation of this phenomenon, looking at the competitiveness of higher education systems in terms of being able to attract talented scientists in their field. We characterise countries capability to offer attractive entry positions into academic careers using the results of a large scale experiment on the determinants of job choice in academia. Examined areas refer to the level of salaries, quality of life, PhD-studies, career perspectives, research organisation, balance between teaching and research, funding and probability of working with high quality peers. Our results indicate that overall, the US research universities offer the most attractive jobs for early stage researchers, consistent with the asymmetric flow of talented scientists to the US. Behind the US is a group of well performing European countries, the Netherlands, Sweden, Switzerland and the UK. Austria and Germany are next, closely followed by France, which in turn is followed by Italy. Spain and Poland are, according to our results, least able to offer attractive entry positions to an academic career
Continual learning with direction-constrained optimization
Full text linkThis paper studies a new design of the optimization algorithm for training
deep learning models with a fixed architecture of the classification network in
a continual learning framework, where the training data is non-stationary and
the non-stationarity is imposed by a sequence of distinct tasks. This setting
implies the existence of a manifold of network parameters that correspond to
good performance of the network on all tasks. Our algorithm is derived from the
geometrical properties of this manifold. We first analyze a deep model trained
on only one learning task in isolation and identify a region in network
parameter space, where the model performance is close to the recovered optimum.
We provide empirical evidence that this region resembles a cone that expands
along the convergence direction. We study the principal directions of the
trajectory of the optimizer after convergence and show that traveling along a
few top principal directions can quickly bring the parameters outside the cone
but this is not the case for the remaining directions. We argue that
catastrophic forgetting in a continual learning setting can be alleviated when
the parameters are constrained to stay within the intersection of the plausible
cones of individual tasks that were so far encountered during training.
Enforcing this is equivalent to preventing the parameters from moving along the
top principal directions of convergence corresponding to the past tasks. For
each task we introduce a new linear autoencoder to approximate its
corresponding top forbidden principal directions. They are then incorporated
into the loss function in the form of a regularization term for the purpose of
learning the coming tasks without forgetting. We empirically demonstrate that
our algorithm performs favorably compared to other state-of-art
regularization-based continual learning methods, including EWC and SI
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