Anomalous velocity distributions in active Brownian suspensions

Large scale simulations and analytical theory have been combined to obtain the non-equilibrium velocity distribution, $f(v)$, of randomly accelerated particles in suspension. The simulations are based on an event-driven algorithm, generalised to include friction. They reveal strongly anomalous but largely universal distributions which are independent of volume fraction and collision processes, which suggests a one-particle model should capture all the essential features. We have formulated this one-particle model and solved it analytically in the limit of strong damping, where we find that $f(v)$ decays as $1/v$ for multiple decades, eventually crossing over to a Gaussian decay for the largest velocities. Many particle simulations and numerical solution of the one-particle model agree for all values of the damping.Comment: 6 pages, 5 figure

Hydrodynamic Correlation Functions of a Driven Granular Fluid in Steady State

We study a homogeneously driven granular fluid of hard spheres at intermediate volume fractions and focus on time-delayed correlation functions in the stationary state. Inelastic collisions are modeled by incomplete normal restitution, allowing for efficient simulations with an event-driven algorithm. The incoherent scattering function, F_incoh(q,t), is seen to follow time-density superposition with a relaxation time that increases significantly as volume fraction increases. The statistics of particle displacements is approximately Gaussian. For the coherent scattering function S(q,omega) we compare our results to the predictions of generalized fluctuating hydrodynamics which takes into account that temperature fluctuations decay either diffusively or with a finite relaxation rate, depending on wave number and inelasticity. For sufficiently small wave number q we observe sound waves in the coherent scattering function S(q,omega) and the longitudinal current correlation function C_l(q,omega). We determine the speed of sound and the transport coefficients and compare them to the results of kinetic theory.Comment: 10 pages, 16 figure

Heterogeneities in the Glassy State

We study heterogeneities in a binary Lennard-Jones system below the glass transition using molecular dynamics simulations. We identify mobile and immobile particles and measure their distribution of vibrational amplitudes. For temperatures near the glass transition the distribution of vibrational amplitudes obeys scaling and compares reasonably well with a mean field theory for the amorphous solid state. To investigate correlations among the immobile and mobile particles we identify clusters and analyze their size and shape. For a fixed number of immobile particles we observe that the immobile particles cluster more strongly together as the temperature is increased which allows the particles to block each other more effectively, and to therefore stay immobile. For the mobile particles, on the other hand, the clustering is most pronounced at small temperatures, indicating that mobility at low temperatures can only be sustained in cooperative motion.Comment: 9 pages, 15 figure

Differences in Leadership Behaviors of Principals and Success in the School Turnaround Processes

The purpose of this study was to examine leadership behaviors of principals associated with public elementary schools that were either in the school turnaround process or had already transitioned out of school academic turnaround from 2011 through 2016. Transformational leadership guided the study to determine whether leadership behaviors differed among leaders of schools associated with academic failure. School accountability data were initially gathered through the Louisiana Department of Education website. Academically unsuccessful schools (AUS) were identified. Schools that were deemed failing at least one time during the 2012-2016 timeframe were grouped as follows: (a) Group A consisted of two schools that had been out of AUS status for at least two years, (b) Group B consisted of two schools that had fluctuated in and out of AUS status, and (c) Group C consisted of two schools that had never exited out of AUS status. Teacher and principal perceptions of leadership were compared between principals of the three groups, between teachers of the three groups, and between principals and teachers between the three groups. In this quantitative study, data were gathered using the Multi-Factor Leadership Questionnaire (MLQ) which measures leader and follower perceptions of leadership behaviors within an organization. The study participants were six principals, who used the Leader form of the MLQ, and 84 teachers, who used the Rater form of the MLQ. The MLQ contains 45 standardized items that are grouped into four categories: (a) Transformational Leadership, (b) Transactional iv Leadership, (c) Laissez-faire Leadership, and (d) Outcomes of Leadership. The results of the MLQ survey were converted into SPSS for analysis. One-way analysis of variances (ANOVA) and Mann-Whitney U Tests revealed significant differences between perceptions of leadership behaviors of leaders from schools that had exited out of AUS status, schools that had fluctuated in and out of AUS status, and schools that had never exited out of AUS status. Recommendations for future research and implications for practice are also included

Slow and Long-ranged Dynamical Heterogeneities in Dissipative Fluids

A two-dimensional bidisperse granular fluid is shown to exhibit pronounced long-ranged dynamical heterogeneities as dynamical arrest is approached. Here we focus on the most direct approach to study these heterogeneities: we identify clusters of slow particles and determine their size, $N_c$, and their radius of gyration, $R_G$. We show that $N_c\propto R_G^{d_f}$, providing direct evidence that the most immobile particles arrange in fractal objects with a fractal dimension, $d_f$, that is observed to increase with packing fraction $\phi$. The cluster size distribution obeys scaling, approaching an algebraic decay in the limit of structural arrest, i.e., $\phi\to\phi_c$. Alternatively, dynamical heterogeneities are analyzed via the four-point structure factor $S_4(q,t)$ and the dynamical susceptibility $\chi_4(t)$. $S_4(q,t)$ is shown to obey scaling in the full range of packing fractions, $0.6\leq\phi\leq 0.805$, and to become increasingly long-ranged as $\phi\to\phi_c$. Finite size scaling of $\chi_4(t)$ provides a consistency check for the previously analyzed divergences of $\chi_4(t)\propto (\phi-\phi_c)^{-\gamma_{\chi}}$ and the correlation length $\xi\propto (\phi-\phi_c)^{-\gamma_{\xi}}$. We check the robustness of our results with respect to our definition of mobility. The divergences and the scaling for $\phi\to\phi_c$ suggest a non-equilibrium glass transition which seems qualitatively independent of the coefficient of restitution.Comment: 14 pages, 25 figure

Protocol: Non-antibiotic, alternative approaches to the nursery phase of swine production: a scoping review

It is widely accepted that antibiotic use drives the development of antibiotic resistance. Hence it is important that swine production uses antibiotics in a judicious manner. In addition, the label claim for livestock antibiotic growth promoters (AGP) of importance to humans has been removed in Canada. In reality, antibiotics have contributed greatly to efficiencies in meat production and animal health. A reduction in the use of growth promoting antibiotics has ramifications for costs of meat production and animal welfare given that sick animals need to be treated, often with antibiotics. Consequences of similar AGP bans in swine production in Europe included an immediate increase in therapeutic use of antibiotics considered important for humans, particularly for nursery stage pigs in Denmark and the Netherlands. It is important to identify and advance our knowledge through the existing research of alternative approaches to antibiotic use, in the nursery stage of pig production. Scoping reviews are a relatively novel approach for synthesizing research evidence in the veterinary and livestock production research literature (Pham MT., 2014). They are useful for mapping the extent, range, and nature of existing literature on a broad topic area. In addition, scoping reviews are useful for identifying gaps in the literature and for determining the feasibility of conducting one or more systematic reviews to help answer a specific question about the effectiveness of a specific intervention in a specific population measuring a specific outcome (Arksey and O’Malley, 2005)

The effects on student knowledge and engagement when using a culturally responsive framework to teach ASTR 101

Philosophiae Doctor - PhDThe U.S. has a problem: it is not effectively utilizing all the bright young minds available to its science & engineering workforce. In 2012 the President’s Council of Advisors on Science and Technology (PCAST) reported that a million more STEM professionals in the U.S. workforce were needed over the next decade. PCAST reported that the situation is far worse for underrepresented students, who make up 70% of undergraduate students but only 45% of the STEM degrees. Recent reports suggest women in science and engineering have made small gains, while historically underrepresented ethnic groups (Blacks, Hispanics, American Indians) continue to be significantly underrepresented. The lack of diversity in the U.S. workforce is not reflected in the USA population nor is it reflected in the undergraduate student population. As the U.S. aspires to retain a leadership role in research and development in an increasingly diverse and globally interconnected society, this disparity is unsustainable. What if having more culturally interesting, more culturally responsive STEM classes is a way of increasing the diversity of the science and engineering workforce in the U.S.? This study focuses on a topic that has been generally overlooked by the STEM educational community, but one that is directly relevant to student engagement and learning outcomes: the role of culture as a variable in student learning. This study examines how different pedagogical approaches shape student outcomes in Astronomy 101 courses. In a comparative study two different pedagogical approaches were analyzed using both quantitative and qualitative methods in a semiexperimental nonequivalent group research design. The theories of culturally responsive pedagogy (CRP), active learning theory in STEM, and Indigenous knowledge systems (IKS) ground this approach. The findings of this study show important gains for all students. Underrepresented minority students (URM) in the course with increased culturally responsive pedagogy were exceptionally engaged and learning gains soared. By measure of the concept inventory, the URM students in the course with increased culturally responsive pedagogy outperformed all other students in the study. As the U.S. will have a non-white majority by the year 2045 and diversity in STEM faculty lags there is a need for tangible, evidence-based, culture-based curriculum and pedagogy. There is a problem and based on the evidence found in this study, there is a way to fix it.The U.S. has a problem: it is not effectively utilizing all the bright young minds available to its science & engineering workforce. In 2012 the President’s Council of Advisors on Science and Technology (PCAST) reported that a million more STEM professionals in the U.S. workforce were needed over the next decade. PCAST reported that the situation is far worse for underrepresented students, who make up 70% of undergraduate students but only 45% of the STEM degrees. Recent reports suggest women in science and engineering have made small gains, while historically underrepresented ethnic groups (Blacks, Hispanics, American Indians) continue to be significantly underrepresented. The lack of diversity in the U.S. workforce is not reflected in the USA population nor is it reflected in the undergraduate student population. As the U.S. aspires to retain a leadership role in research and development in an increasingly diverse and globally interconnected society, this disparity is unsustainable. What if having more culturally interesting, more culturally responsive STEM classes is a way of increasing the diversity of the science and engineering workforce in the U.S.? This study focuses on a topic that has been generally overlooked by the STEM educational community, but one that is directly relevant to student engagement and learning outcomes: the role of culture as a variable in student learning. This study examines how different pedagogical approaches shape student outcomes in Astronomy 101 courses. In a comparative study two different pedagogical approaches were analyzed using both quantitative and qualitative methods in a semiexperimental nonequivalent group research design. The theories of culturally responsive pedagogy (CRP), active learning theory in STEM, and Indigenous knowledge systems (IKS) ground this approach. The findings of this study show important gains for all students. Underrepresented minority students (URM) in the course with increased culturally responsive pedagogy were exceptionally engaged and learning gains soared. By measure of the concept inventory, the URM students in the course with increased culturally responsive pedagogy outperformed all other students in the study. As the U.S. will have a non-white majority by the year 2045 and diversity in STEM faculty lags there is a need for tangible, evidence-based, culture-based curriculum and pedagogy. There is a problem and based on the evidence found in this study, there is a way to fix it

Spatio‐temporal trends in caries: A study on children in Berlin‐Mitte

Background: Significant inequalities in caries distribution among children in Germany have been reported, but small-scale areas remain understudied. Aim: To examine spatio-temporal trends in children's dental caries at the small-area level in Berlin-Mitte. Design: Routinely collected data from Berlin's annual Health Examination Surveys were used, which also include information on age, sex, country of origin, and residential area. The study population consists of 14,866 children aged 5 to 7 between 2006 and 2014 in the district of Berlin-Mitte. Outcome variables are the dmft (decayed, missing, and filled teeth), the presence of any caries experience, untreated caries, and caries risk. The outcomes are summarized descriptively and graphically presented for 10 quarters and 41 communities within Berlin-Mitte. Results: Relevant gaps in children's dental caries were discovered between the quarters of Mitte. Three quarters in the northeast part of Mitte have consistently indicated the lowest oral health status in all four outcomes, and children having high caries risk have been increasingly concentrating in this area over time. Despite the continuous improvements in the southern part, the averages in total of Mitte for all outcomes have risen. Conclusion: Our findings confirm the spatiotemporally mounting disparities in children's oral health between the quarters in Berlin-Mitte and that particular quarters need urgent attention. The small-area approach made it easier and more effective to reveal the spatial distribution of children's dental caries at the local level. The small-area analysis should be strongly encouraged in future caries research to narrow the inequalities in children's oral health