Entropy and specific heat for open systems in steady states

The fundamental assumption of statistical mechanics is that the system is equally likely in any of the accessible microstates. Based on this assumption, the Boltzmann distribution is derived and the full theory of statistical thermodynamics can be built. In this paper, we show that the Boltzmann distribution in general can not describe the steady state of open system. Based on the effective Hamiltonian approach, we calculate the specific heat, the free energy and the entropy for an open system in steady states. Examples are illustrated and discussed.Comment: 4 pages, 7 figure

Multi-agent collaborative search : an agent-based memetic multi-objective optimization algorithm applied to space trajectory design

This article presents an algorithm for multi-objective optimization that blends together a number of heuristics. A population of agents combines heuristics that aim at exploring the search space both globally and in a neighbourhood of each agent. These heuristics are complemented with a combination of a local and global archive. The novel agent-based algorithm is tested at first on a set of standard problems and then on three specific problems in space trajectory design. Its performance is compared against a number of state-of-the-art multi-objective optimization algorithms that use the Pareto dominance as selection criterion: non-dominated sorting genetic algorithm (NSGA-II), Pareto archived evolution strategy (PAES), multiple objective particle swarm optimization (MOPSO), and multiple trajectory search (MTS). The results demonstrate that the agent-based search can identify parts of the Pareto set that the other algorithms were not able to capture. Furthermore, convergence is statistically better although the variance of the results is in some cases higher

Modulational instability criteria for two-component Bose-Einstein condensates

The stability of colliding Bose-Einstein condensates is investigated. A set of coupled Gross-Pitaevskii equations is thus considered, and analyzed via a perturbative approach. No assumption is made on the signs (or magnitudes) of the relevant parameters like the scattering lengths and the coupling coefficients. The formalism is therefore valid for asymmetric as well as symmetric coupled condensate wave states. A new set of explicit criteria is derived and analyzed. An extended instability region, in addition to an enhanced instability growth rate is predicted for unstable two component bosons, as compared to the individual (uncoupled) state.Comment: 4 pages, 1 figur

Analysis of some global optimization algorithms for space trajectory design

In this paper, we analyze the performance of some global search algorithms on a number of space trajectory design problems. A rigorous testing procedure is introduced to measure the ability of an algorithm to identify the set of ²-optimal solutions. From the analysis of the test results, a novel algorithm is derived. The development of the novel algorithm starts from the redefinition of some evolutionary heuristics in the form of a discrete dynamical system. The convergence properties of this discrete dynamical system are used to derive a hybrid evolutionary algorithm that displays very good performance on the particular class of problems presented in this paper

Prevalence study of yaws in the Democratic Republic of Congo using the lot quality assurance sampling method.

BACKGROUND: Until the 1970s the prevalence of non-venereal trepanomatosis, including yaws, was greatly reduced after worldwide mass treatment. In 2005, cases were again reported in the Democratic Republic of the Congo. We carried out a survey to estimate the village-level prevalence of yaws in the region of Equator in the north of the country in order to define appropriate strategies to effectively treat the affected population. METHODOLOGY/PRINCIPAL FINDINGS: We designed a community-based survey using the Lot Quality Assurance Sampling method to classify the prevalence of active yaws in 14 groups of villages (lots). The classification into high, moderate, or low yaws prevalence corresponded to World Health Organization prevalence thresholds for identifying appropriate operational treatment strategies. Active yaws cases were defined by suggestive clinical signs and positive rapid plasma reagin and Treponema pallidum hemagglutination serological tests. The overall prevalence in the study area was 4.7% (95% confidence interval: 3.4-6.0). Two of 14 lots had high prevalence (>10%), three moderate prevalence (5-10%) and nine low prevalence (<5%.). CONCLUSIONS/SIGNIFICANCE: Although yaws is no longer a World Health Organization priority disease, the presence of yaws in a region where it was supposed to be eradicated demonstrates the importance of continued surveillance and control efforts. Yaws should remain a public health priority in countries where previously it was known to be endemic. The integration of sensitive surveillance systems together with free access to effective treatment is recommended. As a consequence of our study results, more than 16,000 people received free treatment against yaws

Promoting deep learning through design - discussion, student activity and assessment

There is widespread evidence that Australia is currently facing falling student participation rates in science and mathematics subjects at secondary school and university undergraduate levels. The future implications of this science-deficit are widely acknowledged. Unfortunately, science teaching itself is also widely seen as being dull, too content-heavy, delivered to mass-audiences and assessed in ways promoting surface approaches to learning. To address these issues, and issues relating to the apparent lack of challenge for very able students in their first year at university, The University of Queensland developed the Advanced Study Program in Science (ASPinS). This initiative offers an enhanced learning experience to a select group of high-achieving students in addition to their existing undergraduate study in a Science-related degree program. ASPinS offers these students the opportunity to interact with leading research scientists, broaden their understanding of important scientific issues, experience new interactive learning opportunities, undertake research projects and obtain an authentic insight into science as a career. This presentation, however, will only focus on the unique first year course offered within the 3 year ASPinS experience – BIOL1017 “Perspectives in Science”. In this course students are encouraged to think about important current scientific issues from different perspectives – both scientific and non-scientific. Panels of expert scientists use their knowledge and experience to present real scientific issues for students to examine and discuss. These panel discussions cover a spectrum of medical, environmental and social issues, covering different viewpoints and possible solutions. Combining this effective panel model with an array of student-led activities provides an ideal environment for learning. Students are made to apply their new knowledge, discuss issues and construct thoughts, opinions and products – depending on the specifically designed activities. Relevant assessment tasks include group-writing activities and oral presentations which enable students to demonstrate their learning through authentic contexts that are carefully designed to influence the way students learn. Authentic assessment tasks enable students to see a purpose for the product (assessment) they are producing while at the same time enabling them to synthesise the various scientific ‘facts’ and issues they have been discussing. This level of assessment activity, by its nature, encourages higher-order learning. Student evaluations have consistently confirmed that the key to the success of each Module within the course lies in the breadth of speakers selected to represent the different angles associated with the topic under discussion and the related activities and assessment tasks. The findings indicate that students value the opportunity to explore the multi-disciplinary nature of science-related issues and to actually discuss the issues. The “Perspectives in Science” course is a model for the success of combining teaching and learning theory and scholarship, to a particular set of objectives, to create a highly effective learning environment and a meaningful student experience

Reshaping graduate outcomes of science students – The contribution of undergraduate research experiences

Today’s science graduates require substantially different skills compared to yesterday’s graduates given the changing nature of modern science. As higher education institutions struggle to reform curricula and pedagogy, undergraduate research experiences (UREs) are increasingly being incorporated to enhance undergraduate science curricula. This study is situated within a traditional Bachelor of Science degree that offers students some voluntary opportunities to participate in UREs. This study explores two graduating science cohorts (n=272), comparing those who did and did not participate in UREs. A survey investigated student perceptions (importance, confidence and improvements) of five graduate outcomes in the context of science: writing skills, communication skills, quantitative skills (QS), teamwork skills and content knowledge. Cross-tabs and a linear discriminant analysis were used to investigate perception change between the two groups. The notable differences in perception scores in this study were consistently higher in QS, perhaps indicative of UREs emphasising the need for such skills in science or from students gaining increased confidence as a result of utilising QS within an authentic context. Our results reveal little difference in other student outcome areas, which raises questions around the role of UREs as a broad strategy for enhancing the achievement of graduate outcomes in science. This study is limited to a single institution and is focused on specific graduate outcomes, so only limited conclusions can be drawn. However, further research to determine the graduate outcomes gained from UREs would benefit the sector, particularly science disciplines, in the changing focus of government policy on student learning outcomes

Assessment of the PROBIT approach for estimating the prevalence of global, moderate and severe acute malnutrition from population surveys

Abstract Objective Prevalence of acute malnutrition is classically estimated by the proportion of children meeting a case definition in a representative population sample. In 1995 the WHO proposed the PROBIT method, based on converting parameters of a normally distributed variable to cumulative probability, as an alternative method requiring a smaller sample size. The present study compares classical and PROBIT methods for estimating the prevalence of global, moderate and severe acute malnutrition (GAM, MAM and SAM) defined by weight-for-height Z-score (WHZ) or mid-upper arm circumference (MUAC). Design Bias and precision of classical and PROBIT methods were compared by simulating a total of 1·26 million surveys generated from 560 nutrition surveys. Setting Data used for simulation were derived from nutritional surveys of children aged 6-59 months carried out in thirty-one countries around the world. Subjects Data of 459 036 children aged 6-59 months from representative samples were used to generate simulated populations. Results The PROBIT method provided an estimate of GAM, MAM and SAM using WHZ or MUAC proportional to the true prevalence with a small systematic overestimation. The PROBIT method was more precise than the classical method for estimating the prevalence for GAM, MAM and SAM by WHZ or MUAC for small sample sizes (i.e. n<150 for SAM and GAM; n<300 for MAM), but lost this advantage when sample sizes increased. Conclusions The classical method is preferred for estimating acute malnutrition prevalence from large sample surveys. The PROBIT method may be useful in sentinel-site surveillance systems with small sample size

Student outcomes from diverse undergraduate research experiences - findings from a multi-disciplinary study

Undergraduate research experiences (UREs) provide students with opportunities to engage in high impact experiential learning. UREs have been especially prevalent in the sciences, but there are now extensive banks of case studies demonstrating the use of UREs as an educationally enriching activity in nearly all disciplines. This study investigated the diversity of UREs available across a wide range of disciplines at a large Australian research-intensive university and examined the perceived benefits. Through group interviews with 68 academics, we gathered detailed information about 81 URE activities, across 28 Schools within the institution (representing 77.8% of Schools), ranging from archaeology to political science, from biology to social work and from law to journalism. The most common URE model observed was that of activities embedded in courses. Across disciplines the most common feature was the requirement for students to engage with the research literature in their field. A smaller number of models incorporated features which allowed students to engage in other high impact learning activities such as community-based activities and internships. Although we identified a large ‘set’ of perceived student outcomes across the varied URE models the generic graduate attributes attained by students through these UREs appeared to be independent of the discipline itself. In most cases, the UREs were available to all students rather than an elite or specialist cohort. This leads us to believe that across a range of disciplinary contexts, there are many ways to use UREs to achieve high levels of engagement of large cohorts of students