Graphical Approach to Teaching Compound Interest in High School Math Classes

Report published in the Proceedings of the National Conference on "Education and Research in the Information Society", Plovdiv, May, 2015

Partnership and organizing:an empirical assessment of two contrasting approaches to union revitalization in the UK

The Trades Union Congress (TUC) in Britain has been advocating two contrasting approaches to union revitalization namely: ‘labour—management partnership’ and ‘union organizing’. Using a case study of a public services union this article examines empirically the prospects of union revival offered by these two contrasting approaches. Public services with relatively high union density should offer better prospects for union revival through partnership. However, the authors’ findings indicate that even in public services, partnership was not associated with management’s support for union recruitment, better facility time provisions for union representatives, lower worker grievances or union membership gains. Rank-and-file organizing, on the other hand, was associated with lower worker grievances, greater worker satisfaction with the union, higher worker involvement in union activities and union membership gains. Overall, the findings question the ‘mutual gains’ assertions of partnership advocates and lend support to the critics of partnership who propose an alternative organizing approach to union revitalization.

Truly interactive approaches to browsing image databases

Image collections are ever growing and hence efficient and effective tools to manage these repositories are highly sought after. In this paper, we present effective image browsing systems that are operated on a large multi-touch environment for truly interactive exploration. Not only do image browsers pose a useful alternative to retrieval-based systems, they also provide a visualisation of the whole image collection and allow users to interactively explore particular parts of the collection. Our systems are based on the idea that visually similar images are located close to each other in the visualisation, that image thumbnails are arranged on a regular lattice (either a regular grid projected onto a sphere or a hexagonal lattice), and that large image datasets can be accessed through a hierarchical tree structure. A pilot study has shown that the presented systems do indeed work well and are preferred compared to conventional image browsers. © 2011 IEEE.

The redoxomics of PTEN: walking a fine line between damage and signaling:mass spectrometry-based approaches to study the effect of oxidation on PTEN function, structure, and protein-protein interactions

The research described in this PhD thesis focuses on proteomics approaches to study the effect of oxidation on the modification status and protein-protein interactions of PTEN, a redox-sensitive phosphatase involved in a number of cellular processes including metabolism, apoptosis, cell proliferation, and survival. While direct evidence of a redox regulation of PTEN and its downstream signaling has been reported, the effect of cellular oxidative stress or direct PTEN oxidation on PTEN structure and interactome is still poorly defined. In a first study, GST-tagged PTEN was directly oxidized over a range of hypochlorous acid (HOCl) concentration, assayed for phosphatase activity, and oxidative post-translational modifications (oxPTMs) were quantified using LC-MS/MS-based label-free methods. In a second study, GSTtagged PTEN was prepared in a reduced and reversibly H2O2-oxidized form, immobilized on a resin support and incubated with HCT116 cell lysate to capture PTEN interacting proteins, which were analyzed by LC-MS/MS and comparatively quantified using label-free methods. In parallel experiments, HCT116 cells transfected with a GFP-tagged PTEN were treated with H2O2 and PTENinteracting proteins immunoprecipitated using standard methods. Several high abundance HOCl-induced oxPTMs were mapped, including those taking place at amino acids known to be important for PTEN phosphatase activity and protein-protein interactions, such as Met35, Tyr155, Tyr240 and Tyr315. A PTEN redox interactome was also characterized, which identified a number of PTEN-interacting proteins that vary with the reversible inactivation of PTEN caused by H2O2 oxidation. These included new PTEN interactors as well as the redox proteins peroxiredoxin-1 (Prdx1) and thioredoxin (Trx), which are known to be involved in the recycling of PTEN active site following H2O2-induced reversible inactivation. The results suggest that the oxidative modification of PTEN causes functional alterations in PTEN structure and interactome, with fundamental implications for the PTEN signaling role in many cellular processes, such as those involved in the pathophysiology of disease and ageing.

A közérdek védelmének intézményei Public-Private Partnership esetében = Institutional approaches to protecting public interest in Public-Private Partnership projects

A tanulmány a Public-Private Partnership (PPP) egyik nagy kérdésének megközelítéseit vizsgálja: miként védhető a közérdek e projektekben. Piaci és nem piaci megoldásokat tesz az elemzés mérlegre, valamint kitér arra, hogy miért különleges a PPP projektek esetében a közérdek védelmének kérdése. A szabályozott verseny körülményeinek kialakítása több megközelítésben is perdöntő kérdés a PPP értéknövelésének előmozdításához, bár a létező megoldások nem mentesek anomáliáktól. A képviseleti demokrácia intézményi működésének támogatására pedig a társadalmi részvétel megoldásait javasolja az irodalom. E megközelítés is több formájában, többféle céllal és szintén kihívásokkal segítheti az értéknövelő PPP projekteket. A tanulmány az elvi lehetőségek értékelő elemzését követően a megvalósítás realitásait is mérlegre teszi. = This study focuses on a key issue in Public-Private Partnership (PPP) projects: how may public interest be protected. It assesses market based and non market based approaches, and also explains why PPP projects are peculiar when addressing the protection of public interest. Setting up the conditions for simulated competition is of paramount importance for different reasons in order to enable value creating PPP projects. Existing solutions however are not without anomalies. To promote the institutions of democracy, participatory solutions are recommended in the literature. That approach may help value creating PPP projects in various forms, with a range of objectives and challenges. The study concludes the analytical assessment of options by highlighting the realistic conditions of implementation.

Neumann versus Leontief. Két modell – két gazdaságkép (Neumann vs Leontief. Two models, two approaches to the economy)

A szerző a tisztán elméleti célokra kifejlesztett Neumann-modellt és a gyakorlati alkalmazások céljára kifejlesztett Leontief-modellt veti össze. A Neumann-modell és a Leontief-modell éves termelési periódust feltételező, zárt, stacionárius változatának hasonló matematikai struktúrája azt a feltételezést sugallja, hogy az utóbbi a Neumann-modell sajátos eseteként értelmezhető. Az egyes modellek közgazdasági tartalmát és feltevéseit részletesen kibontva és egymással összevetve a szerző megmutatja, hogy a fenti következtetés félrevezető, két merőben különböző modellről van szó, nem lehet az egyikből a másikat levezetni. Az ikertermelés és technológiai választék lehetősége a Neumann-modell elengedhetetlen feltevése, az éves termelési periódus feltevése pedig kizárja folyam jellegű kibocsátások explicit figyelembevételét. Mindezek feltevések ugyanakkor idegenek a Leontief-modelltől. A két modell valójában egy általánosabb állomány–folyam jellegű zárt, stacionárius modell sajátos esete, méghozzá azok folyamváltozókra redukált alakja. _____ The paper compares the basic assumptions and methodology of the Von Neumann model, developed for purely abstract theoretical purposes, and those of the Leontief model, designed originally for practical applications. Study of the similar mathematical structures of the Von Neumann model and the closed, stationary Leontief model, with a unit length of production period, often leads to the false conclusion that the latter is just a simplified version of the former. It is argued that the economic assumptions of the two models are quite different, which makes such an assertion unfounded. Technical choice and joint production are indispensable features of the Von Neumann model, and the assumption of unitary length of production period excludes the possibility of taking service flows explicitly into account. All these features are completely alien to the Leontief model, however. It is shown that the two models are in fact special cases of a more general stock-flow stationary model, reduced to forms containing only flow variables.

An innovative approach to teaching structural induction for computer science

Proofs by induction are central to many computer science areas such as data structures, theory of computation, programming languages, program efficiency-time complexity, and program correctness. Proofs by induction can also improve students’ understanding and performance of computer science concepts such as programming languages, algorithm design, and recursion, as well as serve as a medium for teaching them. Even though students are exposed to proofs by induction in many courses of their curricula, they still have difficulties understanding and performing them. This impacts the whole course of their studies, since proofs by induction are omnipresent in computer science. Specifically, students do not gain conceptual understanding of induction early in the curriculum and as a result, they have difficulties applying it to more advanced areas later on in their studies. The goal of my dissertation is twofold: (1) identifying sources of computer science students’ difficulties with proofs by induction, and (2) developing a new approach to teaching proofs by induction by way of an interactive and multimodal electronic book (e-book). For the first goal, I undertook a study to identify possible sources of computer science students’ difficulties with proofs by induction. Its results suggest that there is a close correlation between students’ understanding of inductive definitions and their understanding and performance of proofs by induction. For designing and developing my e-book, I took into consideration the results of my study, as well as the drawbacks of the current methodologies of teaching proofs by induction for computer science. I designed my e-book to be used as a standalone and complete educational environment. I also conducted a study on the effectiveness of my e-book in the classroom. The results of my study suggest that, unlike the current methodologies of teaching proofs by induction for computer science, my e-book helped students overcome many of their difficulties and gain conceptual understanding of proofs induction.

Hybrid approaches to estimating freeway travel times using point traffic detector data

The accurate and reliable estimation of travel time based on point detector data is needed to support Intelligent Transportation System (ITS) applications. It has been found that the quality of travel time estimation is a function of the method used in the estimation and varies for different traffic conditions. In this study, two hybrid on-line travel time estimation models, and their corresponding off-line methods, were developed to achieve better estimation performance under various traffic conditions, including recurrent congestion and incidents. The first model combines the Mid-Point method, which is a speed-based method, with a traffic flow-based method. The second model integrates two speed-based methods: the Mid-Point method and the Minimum Speed method. In both models, the switch between travel time estimation methods is based on the congestion level and queue status automatically identified by clustering analysis. During incident conditions with rapidly changing queue lengths, shock wave analysis-based refinements are applied for on-line estimation to capture the fast queue propagation and recovery. Travel time estimates obtained from existing speed-based methods, traffic flow-based methods, and the models developed were tested using both simulation and real-world data. The results indicate that all tested methods performed at an acceptable level during periods of low congestion. However, their performances vary with an increase in congestion. Comparisons with other estimation methods also show that the developed hybrid models perform well in all cases. Further comparisons between the on-line and off-line travel time estimation methods reveal that off-line methods perform significantly better only during fast-changing congested conditions, such as during incidents. The impacts of major influential factors on the performance of travel time estimation, including data preprocessing procedures, detector errors, detector spacing, frequency of travel time updates to traveler information devices, travel time link length, and posted travel time range, were investigated in this study. The results show that these factors have more significant impacts on the estimation accuracy and reliability under congested conditions than during uncongested conditions. For the incident conditions, the estimation quality improves with the use of a short rolling period for data smoothing, more accurate detector data, and frequent travel time updates.

Roadblocks to Teaching English as a Foreign Language in a Climate of Accelerated Curricular Change

This paper examines the global "English craze," in which non-Englishspeaking countries, especially in Asia, East Asia, and the Middle East, are engaged in a concerted push to get the language taught more widely and at increasingly lower grade levels. The goal of this paper is to document how this phenomenon has impacted teachers of English as a Foreign Language and how they can try to alleviate these problems.

Marketing Approaches to Human Resources Management In the Hospitality Industry

Now that baby boomers are older and pursuing more career-oriented jobs, managers of the hospitality industry are experiencing the effects of the pre- sent labor crisis; they now know that those vacant hourly jobs are going to be tough to fill with quality personnel. The companies able to attract quality personnel by offering employees what they need and want will be the successful ones in the next decade. The authors explain how the labor crisis is currently affecting the hospitality industry and make suggestions about how firms may survive the "labor crash” of the 1990s with the application of marketing technology to human resource management.

Development of effective approaches to the large-scale aerodynamic testing of low-rise buildings

Low-rise buildings are often subjected to high wind loads during hurricanes that lead to severe damage and cause water intrusion. It is therefore important to estimate accurate wind pressures for design purposes to reduce losses. Wind loads on low-rise buildings can differ significantly depending upon the laboratory in which they were measured. The differences are due in large part to inadequate simulations of the low-frequency content of atmospheric velocity fluctuations in the laboratory and to the small scale of the models used for the measurements. A new partial turbulence simulation methodology was developed for simulating the effect of low-frequency flow fluctuations on low-rise buildings more effectively from the point of view of testing accuracy and repeatability than is currently the case. The methodology was validated by comparing aerodynamic pressure data for building models obtained in the open-jet 12-Fan Wall of Wind (WOW) facility against their counterparts in a boundary-layer wind tunnel. Field measurements of pressures on Texas Tech University building and Silsoe building were also used for validation purposes. The tests in partial simulation are freed of integral length scale constraints, meaning that model length scales in such testing are only limited by blockage considerations. Thus the partial simulation methodology can be used to produce aerodynamic data for low-rise buildings by using large-scale models in wind tunnels and WOW-like facilities. This is a major advantage, because large-scale models allow for accurate modeling of architectural details, testing at higher Reynolds number, using greater spatial resolution of the pressure taps in high pressure zones, and assessing the performance of aerodynamic devices to reduce wind effects. The technique eliminates a major cause of discrepancies among measurements conducted in different laboratories and can help to standardize flow simulations for testing residential homes as well as significantly improving testing accuracy and repeatability. Partial turbulence simulation was used in the WOW to determine the performance of discontinuous perforated parapets in mitigating roof pressures. The comparisons of pressures with and without parapets showed significant reductions in pressure coefficients in the zones with high suctions. This demonstrated the potential of such aerodynamic add-on devices to reduce uplift forces.

Synthetic Approaches to Flexible Fluorescent Conjugated Polymers

Conjugated polymers (CPs) are intrinsically fluorescent materials that have been used for various biological applications including imaging, sensing, and delivery of biologically active substances. The synthetic control over flexibility and biodegradability of these materials aids the understanding of the structure-function relationships among the photophysical properties, the self-assembly behaviors of the corresponding conjugated polymer nanoparticles (CPNs), and the cellular behaviors of CPNs, such as toxicity, cellular uptake mechanisms, and sub-cellular localization patterns. Synthetic approaches towards two classes of flexible CPs with well-preserved fluorescent properties are described. The synthesis of flexible poly(p-phenylenebutadiynylene)s (PPBs) uses competing Sonogashira and Glaser coupling reactions and the differences in monomer reactivity to incorporate a small amount (~10%) of flexible, non-conjugated linkers into the backbone. The reaction conditions provide limited control over the proportion of flexible monomer incorporation. Improved synthetic control was achieved in a series of flexible poly(p-phenyleneethynylene)s (PPEs) using modified Sonogashira conditions. In addition to controlling the degree of flexibility, the linker provides disruption of backbone conjugation that offers control of the length of conjugated segments within the polymer chain. Therefore, such control also results in the modulation of the photophysical properties of the materials. CPNs fabricated from flexible PPBs are non-toxic to cells, and exhibit subcellular localization patterns clearly different from those observed with non-flexible PPE CPNs. The subcellular localization patterns of the flexible PPEs have not yet been determined, due to the toxicity of the materials, most likely related to the side-chain structure used in this series. The study of the effect of CP flexibility on self-assembly reorganization upon polyanion complexation is presented. Owing to its high rigidity and hydrophobicity, the PPB backbone undergoes reorganization more readily than PPE. The effects are enhanced in the presence of the flexible linker, which enables more efficient π-π stacking of the aromatic backbone segments. Flexibility has minimal effects on the self-assembly of PPEs. Understanding the role of flexibility on the biophysical behaviors of CPNs is key to the successful development of novel efficient fluorescent therapeutic delivery vehicles.

An Innovative Approach to Teaching Structural Induction for Computer Science

Proofs by induction are central to many computer science areas such as data structures, theory of computation, programming languages, program efficiency-time complexity, and program correctness. Proofs by induction can also improve students’ understanding of and performance with computer science concepts such as programming languages, algorithm design, and recursion, as well as serve as a medium for teaching them. Even though students are exposed to proofs by induction in many courses of their curricula, they still have difficulties understanding and performing them. This impacts the whole course of their studies, since proofs by induction are omnipresent in computer science. Specifically, students do not gain conceptual understanding of induction early in the curriculum and as a result, they have difficulties applying it to more advanced areas later on in their studies. The goal of my dissertation is twofold: 1. identifying sources of computer science students’ difficulties with proofs by induction, and 2. developing a new approach to teaching proofs by induction by way of an interactive and multimodal electronic book (e-book). For the first goal, I undertook a study to identify possible sources of computer science students’ difficulties with proofs by induction. Its results suggest that there is a close correlation between students’ understanding of inductive definitions and their understanding and performance of proofs by induction. For designing and developing my e-book, I took into consideration the results of my study, as well as the drawbacks of the current methodologies of teaching proofs by induction for computer science. I designed my e-book to be used as a standalone and complete educational environment. I also conducted a study on the effectiveness of my e-book in the classroom. The results of my study suggest that, unlike the current methodologies of teaching proofs by induction for computer science, my e-book helped students overcome many of their difficulties and gain conceptual understanding of proofs induction.

Analysis of residuals in contingency tables: another nail in the coffin of conditional approaches to significance testing.

Omnibus tests of significance in contingency tables use statistics of the chi-square type. When the null is rejected, residual analyses are conducted to identify cells in which observed frequencies differ significantly from expected frequencies. Residual analyses are thus conditioned on a significant omnibus test. Conditional approaches have been shown to substantially alter type I error rates in cases involving t tests conditional on the results of a test of equality of variances, or tests of regression coefficients conditional on the results of tests of heteroscedasticity. We show that residual analyses conditional on a significant omnibus test are also affected by this problem, yielding type I error rates that can be up to 6 times larger than nominal rates, depending on the size of the table and the form of the marginal distributions. We explored several unconditional approaches in search for a method that maintains the nominal type I error rate and found out that a bootstrap correction for multiple testing achieved this goal. The validity of this approach is documented for two-way contingency tables in the contexts of tests of independence, tests of homogeneity, and fitting psychometric functions. Computer code in MATLAB and R to conduct these analyses is provided as Supplementary Material.

Modelling the cost-effectiveness of adopting risk stratified approaches to extended screening intervals in the national diabetic retinopathy screening programme in Scotland

Funding sources: The study was funded by a research grant from the Chief Scientist’s Office of the Scottish Government Health and Social Care Directorates (CZH/4/971). The funder played no role in study design, data collection, data analysis, manuscript preparation and/or publication decisions. The views expressed herein are those of the authors and do not necessarily reflect those of the funder.