Pure gauge theory for the gravitational spin connection

The gravitational spin connection appears in gravity as a non-Abelian gauge field for the Lorentz group $SO(3,1)$, which is non-compact. The action for General Relativity is linear in the field strength associated to the spin connection, and its equation of motion corresponds to the standard metricity constraint. Consequently, the zero-torsion spin connection is never realized as an independent degree of freedom and is determined by the vierbein field. In this work, we take a different perspective and consider a pure Yang-Mills theory for the spin connection coupled to Dirac fermions, resulting in the former being a dynamical field. After discussing various approaches towards managing the pathologies associated with non-compact gauge theories, we compute the tree-level amplitude for fermion scattering via a spin connection exchange. In contrast to integrating out torsion in the presence of fermions, the model induces a chiral four-Fermi like term that involves a right-right current interaction, which is not present in the Standard Model.Comment: 6 pages, 1 figure, comments welcom

Engineering design applications of surrogate-assisted optimization techniques

The construction of models aimed at learning the behaviour of a system whose responses to inputs are expensive to measure is a branch of statistical science that has been around for a very long time. Geostatistics has pioneered a drive over the last half century towards a better understanding of the accuracy of such ‘surrogate’ models of the expensive function. Of particular interest to us here are some of the even more recent advances related to exploiting such formulations in an optimization context. While the classic goal of the modelling process has been to achieve a uniform prediction accuracy across the domain, an economical optimization process may aim to bias the distribution of the learning budget towards promising basins of attraction. This can only happen, of course, at the expense of the global exploration of the space and thus finding the best balance may be viewed as an optimization problem in itself. We examine here a selection of the state of-the-art solutions to this type of balancing exercise through the prism of several simple, illustrative problems, followed by two ‘real world’ applications: the design of a regional airliner wing and the multi-objective search for a low environmental impact hous

The π\pi-axion and π\pi-axiverse of dark QCD

Axions and axion-like particles (ALPs) are a prominent dark matter candidate, drawing motivation in part from the axiverse of string theory. Axion-like particles can also arise as composite degrees of freedom of a dark sector, for example, as dark pions in dark Quantum Chromo-Dynamics. In a dark Standard Model (SM) wherein all 6 quark flavors are light while the photon is massive, one finds a rich low-energy spectrum of stable and ultralight particles, in the form of neutral and charged dark scalars, and complex neutral scalars analogous to the SM kaon, with mass splittings determined by the mass and charge of the dark quarks. The model finds a natural portal to the visible sector via kinetic coupling of the dark and visible photons, and consequent millicharges for dark matter. The dark matter can be a mixture of all these ultralight bosonic degrees of freedom, and exhibit both parity-even and parity-odd interactions, making the theory testable at a wide variety of experiments. In context of dark QCD with $N_f$ flavors of light quarks, this scenario predicts $N_f^2-1$ ultralight axion-like particles -- effectively an axiverse from dark QCD. This '$\pi$-axiverse' is consistent with but makes no recourse to string theory, and is complementary to the conventional string theory axiverse

Ultraproducts of measure preserving actions and graph combinatorics

Ultraproducts of measure preserving actions of countable groups are used to study the graph combinatorics associated with such actions, including chromatic, independence and matching numbers. Applications are also given to the theory of random colorings of Cayley graphs and sofic actions and equivalence relations

Epochs of Ecology: The Transition from Feudalism to Capitalism

The transition from feudalism to capitalism has undoubtedly been one of the most fruitful and complicated debates amongst economic historians in the 20th and 21st centuries. With the advent of global ecological collapse, there is a necessity to examine and theorize the movement from feudalism to capitalism through the lens of ecology. While in mainstream economics the environment is either entirely dismissed or nature’s role in economics remains subsidiary to the human economy, in the field of Marxian economics, human’s interacting through nature is at the core of the entire theory. For that reason, this thesis takes earnestly Marx’s contributions to ecology, while also utilizing a broadly Marxian approach to grasp the social and natural dynamic forces involved in the transition from feudalism to capitalism in England from the 14th to the 19th century. This thesis historically examines the dissolution of the feudal mode and the rise of the capitalist mode by highlighting three socio-natural relationships vital for the transition: the relationship to agriculture, wool and textile production, and mining. By exploring these relationships historically through the lens of economics and ecology, we will characterize most aptly the rupture in ecology brought about by the capitalist mode

Appraisal -Tendency Framework: Emotions and Perceptions of Social Injustice

This research project studies the Appraisal-Tendency Framework. Specifically, it observes whether emotional dispositions, such as sadness-proneness or trait anger, affect judgements made on whether a situation is just or unjust. In addition, this study also presents the question of whether gender impacts perceptions of fairness. All participants will be recruited from a Southeastern University. This study consists of two parts. For part one, all participants will complete an online survey to assess individual differences. Part two contains the experimental manipulations. This study uses a 2 (emotional induction) x 2 (gender of actor) design. For the emotional induction, participants will be randomly assigned to view a clip meant to induce feelings of sadness or feelings of anger. All participants will be asked to write a short response of a real-life emotional experience matching the emotion of the condition they are assigned to. They will then be randomly assigned to view a clip of an unjust situation carried out by either a female professor or a male professor. The outcome of this study could provide organizations with a better understanding of why certain emotions relate to certain judgements and decisions

Clinical and surgical management of holocervical spinal cord ependymomas.

Background:Spinal ependymomas are rare tumors of the central nervous system, and those spanning the entire cervical spine are atypical. Here, we present two unusual cases of holocervical (C1-C7) spinal ependymomas. Case Description:Two patients, a 32-year-old female and a 24-year-old male presented with neck pain, motor, and sensory deficits. Sagittal MRI confirmed hypointense lesions on T1 and hyperintense regions on T2 spanning the entire cervical spine. These were accompanied by cystic cavities extending caudally into the thoracic spine and rostrally to the cervicomedullary junction. Both patients underwent gross total resection of these lesions and sustained excellent recoveries. Conclusion:Two holocervical cord intramedullary ependymomas were safely and effectively surgically resected without incurring significant perioperative morbidity

Preceptor Perceptions of Contemporary Practice Skills Amongst New Graduates Amid Community Pharmacy Transformation

As community pharmacy transitions from a fee-for-service model to a focus on value-based care, the desired skills of pharmacist graduates in contemporary practice is an evolving paradigm. Meanwhile, most student pharmacists pursuing a career in community pharmacy upon graduation rely solely upon their pharmacy school training as preparation for entering practice. Community pharmacy preceptors are stakeholders in a unique position to compare the dichotomy of the current climate of community practice with the preparedness of graduating students to enter this field. Therefore, these preceptors’ perceptions of contemporary practice services and skills essential for new graduates may be useful in identifying methods of educating and assessing PharmD candidates in their preparation to enter the evolving landscape of community practice. The objective of this research was to identify essential skills for new graduates in contemporary community pharmacy as perceived by these current practitioners. To accomplish this, researchers developed an anonymous web-based survey using REDCap which was emailed to active Advanced Pharmacy Practice Experiences (APPE) community preceptors. The survey included 3 sections: (1) preceptor demographics; (2) perceptions of “contemporary” services and an evaluation of services offered at their sites; and (3) essential skills for graduates entering contemporary community practice. Following a 30-day window of the survey being open, 25% of preceptors responded (n = 42). Survey responses provided clarity in comparing the proportionality in services offered versus services viewed as contemporary. This information may be useful in identifying transformations that have already seen implementation in practice compared to emerging areas yet to be implemented. We also found broad consensus in the perceived importance of most skill areas offered in the survey with just a few showing broader discrepancies with a minority of respondents suggesting skills which held less importance. Monitoring fluctuations of these parameters over time may disclose trends in community pharmacy practice transformation, further delineating service areas that are trending toward adoption in contemporary practice. Therefore, continued use of preceptor surveys may offer insights on the incremental progression of community pharmacy curricula