Mean Field Description of the Fractional Quantum Hall Effect Near ν=1/(2k+1)\nu=1/(2k+1)

The nature of Mean Field Solutions to the Equations of Motion of the Chern--Simons Landau--Ginsberg (CSLG) description of the Fractional Quantum Hall Effect (FQHE) is studied. Beginning with the conventional description of this model at some chemical potential $\mu_0$ and magnetic field $B$ corresponding to a ``special'' filling fraction $\nu=2\pi\rho/eB=1/n$ ($n=1,3,5\cdot \cdot\cdot$) we show that a deviation of $\mu$ in a finite range around $\mu_0$ does not change the Mean Field solution and thus the mean density of particles in the model. This result holds not only for the lowest energy Mean Field solution but for the vortex excitations as well. The vortex configurations do not depend on $\mu$ in a finite range about $\mu_0$ in this model. However when $\mu-\mu_0 \mu_{cr}^+$) the lowest energy Mean Field solution describes a condensate of vortices (or antivortices). We give numerical examples of vortex and antivortex configurations and discuss the range of $\mu$ and $\nu$ over which the system of vortices is dilute.Comment: Revtex document; 12 pages and 4 postscript figures in a fil

On the Mixing Enhancement in a Meandering Jet Due to the Interaction with an Eddy

The interaction between a simple meandering jet such as the Gulf Stream, and an eddy is shown to greatly enhance the mixing and dispersal of fluid parcels in the jet. This enhanced mixing is quantified by calculating the rate of increase of the root-mean-square pair separation of Lagrangian particles (e.g., floats) launched in the jet\u27s immediate vicinity. In the presence of an eddy, particles can escape from the regions in which they were initially launched. Comparisons with observations show a markedly improved qualitative agreement when the eddy is allowed to interact with the meandering jet

Community Perspectives on Access to and Availability of Healthy Food in Rural, Low-Resource, Latino Communities.

IntroductionAttention has focused on the food environment as a result of the growing concern with obesity rates among Latinos in rural areas. Researchers have observed associations between a lack of physical access to affordable produce in areas where supermarkets and grocery stores are limited and poor dietary intake and obesity; these associations are high in rural, low-resource neighborhoods with a high population of Latino residents. We aimed to engage residents of low-resource, Latino-majority neighborhoods in discussions of food access in a rural yet agricultural community setting, which is typically described as a "food desert."MethodsWe used a mixed-methods approach and conducted 3 focus groups (n = 20) and in-depth interviews (n = 59) and surveys (n = 79) with residents of a rural yet agricultural community. We used thematic analysis to explore residents' perceptions of access to healthy foods.ResultsResidents (n = 79; mean age, 41.6 y; 72% female; 79% Latino; 53% Spanish-speaking) reported that dollar and discount stores in this agricultural area provided access to produce; however, produce at retail stores was less affordable than produce at nonretail outlets such as fruit and vegetable stands. Gifts and trades of fruits and vegetables from neighbors and community organizations supplied no-cost or low-cost healthy foods. Residents' suggestions to improve food access centered on lowering the cost of produce in existing retail outlets and seeking out nonretail outlets.ConclusionOur findings contribute to understanding of the food environment in low-resource, rural yet agricultural areas. Although such areas are characterized as "food deserts," residents identified nonretail outlets as a viable source of affordable produce, while indicating that the cost of retail produce was a concern. Innovative policy solutions to increase healthy food consumption must focus on affordability as well as accessibility, and consider alternate, nonretail food outlets in agricultural areas

Challenges to managing quality of care in northern Queensland residential aged care facilities

Background: Senior management teams in residential aged care facilities (RACFs) face a range of challenges in providing quality health care services. With increasing attention directed at quality problems in Australian RACFs, there is an urgent need to better understand the experiences of this crucial cadre. This qualitative study sought to identify challenges from the perspective of current senior managers in residential aged care (RAC) organisations and map their influence on the quality of health care provided within. Methods: 20 semi-structured interviews were conducted with senior managers in 14 RACFs in northern Queensland, Australia. Thematic analysis was used, combining inductive identification of managerial challenges and a mapping exercise to locate these encounters against health system quality dimensions in the Australian National Health Performance Framework (NHPF). Results: Reported challenges to promoting and sustaining quality health care within RACFs included barriers to recruiting and retaining skilled staff, service constraints resulting from geographical isolation, limited access to quality fiscal resources, and a recent change to regulatory and administrative requirements. Identified challenges touch on all sub-dimensions of the NHPF. Conclusion: Several forces, many structural, currently challenge quality health care services in northern Queensland RACFs. Senior management teams come under substantial pressure and are developing short term solutions to protect quality in the face of often chronic and structural challenges. Alongside work to address macro-level issues, more work is needed to understand the personal and professional attributes of senior managers who are successful in positively influencing facility-level quality issues

Two key events associated with a transposable element burst occurred during rice domestication

Transposable elements shape genome evolution through periodic bursts of amplification. In this study we exploited knowledge of the components of the mPing/Ping/Pong TE family in four rice strains undergoing mPing bursts to track their copy numbers and distribution in a large collection of genomes from the wild progenitor Oryza rufipogon and domesticated Oryza sativa (rice). We characterized two events that occurred to the autonomous Ping element and appear to be critical for mPing hyperactivity. First, a point mutation near the end of the element created a Ping variant ( Ping16A ) with reduced transposition. The proportion of strains with Ping16A has increased during domestication while the original Ping (Ping16G) has been dramatically reduced. Second, transposition of Ping16A into a Stowaway element generated a locus ( Ping16A_Stow ) whose presence correlates with strains that have high mPing copies. Finally, demonstration that Pong elements have been stably silenced in all strains analyzed indicates that sustained activity of the mPing/Ping family during domestication produced the components necessary for the mPing burst, not the loss of epigenetic regulation

Student Gains in Conceptual Understanding in Introductory Statistics with and without a Curriculum Focused on Simulation-Based Inference

Using “simulation-based inference” (SBI) such as randomization tests as the primary vehicle for introducing students to the logic and scope of statistical inference has been advocated with the potential of improving student understanding of statistical inference, as well as the statistical investigative process as a whole. Moving beyond the individual class activity, entirely revised introductory statistics curricula centering on these ideas have been developed and tested. In this presentation we will discuss three years of cross-institutional tertiary-level data in the United States comparing SBI-focused curricula and non-SBI curricula (roughly 15,000 students). We examine several pre/post measures of conceptual understanding in the introductory algebra-based course, using hierarchical modelling to incorporate student-level, instructor-level, and institutional-level covariates

Tuning transcriptional regulation through signaling: A predictive theory of allosteric induction

Allosteric regulation is found across all domains of life, yet we still lack simple, predictive theories that directly link the experimentally tunable parameters of a system to its input-output response. To that end, we present a general theory of allosteric transcriptional regulation using the Monod-Wyman-Changeux model. We rigorously test this model using the ubiquitous simple repression motif in bacteria by first predicting the behavior of strains that span a large range of repressor copy numbers and DNA binding strengths and then constructing and measuring their response. Our model not only accurately captures the induction profiles of these strains but also enables us to derive analytic expressions for key properties such as the dynamic range and $[EC_{50}]$. Finally, we derive an expression for the free energy of allosteric repressors which enables us to collapse our experimental data onto a single master curve that captures the diverse phenomenology of the induction profiles.Comment: Substantial revisions for resubmission (3 new figures, significantly elaborated discussion); added Professor Mitchell Lewis as another author for his continuing contributions to the projec

Reinforcement learning in large, structured action spaces: A simulation study of decision support for spinal cord injury rehabilitation

Reinforcement learning (RL) has helped improve decision-making in several applications. However, applying traditional RL is challenging in some applications, such as rehabilitation of people with a spinal cord injury (SCI). Among other factors, using RL in this domain is difficult because there are many possible treatments (i.e., large action space) and few patients (i.e., limited training data). Treatments for SCIs have natural groupings, so we propose two approaches to grouping treatments so that an RL agent can learn effectively from limited data. One relies on domain knowledge of SCI rehabilitation and the other learns similarities among treatments using an embedding technique. We then use Fitted Q Iteration to train an agent that learns optimal treatments. Through a simulation study designed to reflect the properties of SCI rehabilitation, we find that both methods can help improve the treatment decisions of physiotherapists, but the approach based on domain knowledge offers better performance. Our findings provide a "proof of concept" that RL can be used to help improve the treatment of those with an SCI and indicates that continued efforts to gather data and apply RL to this domain are worthwhile.Comment: 31 pages, 7 figure