bluuebunny/crossref_metadata_2025 huggingface dataset:
Executive learning through case discussion
Authors: C. Ickis John , G. Woodside Arch , Ogliastri Enrique
Published: October 2014

Purpose

– The purpose of this paper is to provide a framework with which to understand the issues that arise in the discussion cases included in this Special Issue and explains the role of case studies in the education of those responsible for leading organizations.

Design/methodology/approach

– This paper is based upon the review of literature from a range of disciplines, all of which is relevant to executive learning; the analysis of the cases and papers in this Special Issue, and interviews with colleagues who use the case method.

Findings

– The case method is useful in the education of managerial decision makers who face complex situations, but it is most effective when the cases contain certain essential ingredients and when the instructor is skilled in discussion leadership. These ingredients include the presence of a protagonist, the deep description of a problematic situation, the existence of at least two reasonable courses of action, and sufficient data to evaluate each alternative. The interactive nature of case discussions reinforces those values and behaviors that associate with civility.

Research limitations/implications

– Since some of the discussion cases were in the process of completion, it was not always possible to evaluate the experience with their use in the classroom.

Practical implications

– The introductory paper points to broader opportunities for the use of the case method, and for its adaptation to experiential learning, than is generally recognized in academia.

Social implications

– The use of discussion cases in management schools, where future business leaders interact with professors and classmates in an environment of critical learning and respect for opinions of others, encourages behaviors of civility.

Originality/value

– This introductory paper is valuable in providing a framework to integrate and make sense of the diverse topics, situations, and contexts described in the cases contained in the Special Issue.
Introducing a disruptive service innovation: a national dilemma in E-Procurement
Authors: Carlos Barahona Juan , M. Elizondo Andrey
Published: October 2014

Purpose

– The purpose of this paper is to illustrate a unique opportunity to analyze the implications of two different approaches to develop and deploy a national public electronic procurement system.

Design/methodology/approach

– The authors used multiple data collection methods. The data were collected from 2009 to 2013 from primary sources, studies, consulting work, seminars, official documents and the written press. The structure includes a teaching case, a teaching note and a discussion on the potential of case research as a powerful method to elicit valuable insights and knowledge creation.

Findings

– The research shows that literature on E-Procurement and E-Government is oblivious to the disruptive character of this technology in public administration. This case allows the discussion on the consequences of this omission for the success of E-Procurement implementations. Lessons drawn are extendable to other E-Government ventures.

Practical implications

– Despite multiple stakeholder views and a long and difficult debate among different technical platforms, the underlying problem remains unnoticed. The authors show that decisions on E-Procurement implementations should also consider organizational design and adoption of innovation strategies. By re-framing the problem, much of the complexity of the decision disappears.

Originality/value

– Many nations around the world are developing or revamping their National Public E-Procurement Systems, this parsimonious account of a complex decision allows for the exploration and discussion of the various complexities surrounding technological innovations in public management and brings light to a critical and mostly ignore success factor associated with the choice on the implementation and operational model.
Pollo Campero in the USA
Authors: R. Brenes Esteban , Chattopadyay Amitava , Ciravegna Luciano , Montoya Daniel
Published: October 2014

Purpose

– This case illustrates the challenges that Pollo Campero, a Guatemalan fast food company, faces when expanding in the US market. The purpose of this paper is to stimulate a discussion about consumer segmentation, competitive strategy and the internationalization of emerging market multinationals.

Design/methodology/approach

– The case study is based on primary research conducted in conjunction with the company, including interviews with senior management and an ample review of documents. Secondary sources have been used to gather information about the industry, the US market and consumer segments.

Findings

– The case illustrates that Pollo Campero was initially very successful in the US market because it appealed to consumers of Central American origin. It found it harder to appeal to a broader range of US consumers, who had no emotional attachment to the brand.

Originality/value

– This is a complex, in-depth case study suitable for use with advanced MBA students and practitioners. Depending on the aims of the instructor, different aspects of the case can be highlighted and it can be used in a competitive strategy class as well as in a corporate strategy class or a strategic marketing course. It can be used in a class focussing on brand, positioning and consumer segmentation, a class on competitive strategy in the fast food industry, or a class on the international strategy of emerging market multinationals.
Supercharging case-based learning via simulators
Authors: Pérez-Bennett Antonio , Davidsen Pål , E. López Luis
Published: October 2014

Purpose

– The purpose of this paper is to examine the use of simulators as pedagogical complements to traditional case studies. The research performs experiments with a case and its accompanying simulator to assess the additional learning attained by the use of a case with its simulator as compared to using the case alone. The paper also describes the development and proposed use of cases and simulators combined.

Design/methodology/approach

– The paper describes the development of one companion simulators, it outlines its proposed use, and it shows the results of an experiment to assess marginal learning with the simulator.

Findings

– The research finds that simulators increase the understanding of subjects when used to support a case study. Students and teachers perceive the use of companion simulators as valuable.

Research limitations/implications

– The research provides ground for developing a new generation of case studies in which the traditional case is enhanced and augmented by simulators developed for one particular case and intended to be used only with that case.

Practical implications

– This research has practical implications in how management is taught and learned.

Social implications

– The paper has implications in terms of possible changes that can be introduced to the teaching of management in business schools.

Originality/value

– This research provides one of the few extant assessments of the learning that can be attained with the use of simulators in management education. The research proposes the creation of a new entity, the “Case+Sim” that draws on the traditional strengths of managerial case studies to be used in educating managers, but complements the case studies with simulators, which provide an added value in permitting students to test their thinking using a realistic interactive learning environment.
Alpha Tech: a Brazilian software firm goes international
Authors: T.A. Moraes Sylvia , da Rocha Angela
Published: October 2014

Purpose

– This strategy-learning case traces the growth of AlphaTech, a publicly traded company in Brazil that is a management software company. The purpose of this paper is to debate whether or not the firm should give more emphasis to internationalization, given its high market share in Brazil, where further gains may be very expensive and difficult. The case is intended to serve as a vehicle to discuss the internationalization process of a software firm from an emerging economy.

Design/methodology/approach

– The case was built using several sources of information, including interviews with two executives in charge of the firm's internationalization process, articles in business newspapers and magazines, a book written by the firm co-founders, reports, and information gathered in the internet.

Findings

– The main issues posed by this case study are: first, the difficulties faced by an emerging market firm to get a sustainable position in international markets; second, the challenges of competing with powerful global multinational corporations (such as SAP and Oracle) in the international marketplace; and third, the need to adapt the firm's international strategy to new threats and opportunities.

Originality/value

– The Brazilian context differs from other BRICS, since Brazilian software firms do not have access to low-cost labor and therefore cannot adopt a low price strategy to compete effectively in international markets, but rather need to build unique capabilities to overcome liabilities of foreignness.
U.S. highway public private partnerships
Authors: Daito Nobuhiko , Gifford Jonathan L.
Published: October 2014

Purpose

– The use of public-private partnerships (P3s) for infrastructure delivery, particularly for highway projects, has been increasing in the USA. The purpose of this paper is to empirically evaluate the difference of P3s and non-P3 highway projects, in terms of their costs and efficiency.

Design/methodology/approach

– An empirical model of highway construction costs was estimated using a linear regression model that explicitly accounts for the cost differential between the contracts. The differences between efficiencies was also evaluated through a two-stage analysis, where projects’-specific technical efficiencies were first estimated using stochastic frontier analysis and data envelopment analysis, and then the difference in technical efficiencies between the two groups were evaluated through non-parametric tests of means.

Findings

– Controlling for various project characteristics, the P3 highway projects in the USA showed higher initial costs than non-P3 projects. However, the efficiency scores showed no significant difference between the two groups. This inconsistency between initial costs and technical efficiency scores suggests the complexity involved in P3 projects, which are not captured in the efficiency analysis.

Research limitations/implications

– Limited availability of P3 project data due to their immaturity (in cases of P3 projects that include operation and management) and their complex engineering specifications may have caused biased results. Importantly, the study analyzed project costs as of financial close; post-financial close variations, such as change orders during construction, cost/schedule overruns, and renegotiation of contract terms, are beyond the scope of the analysis in this study.

Originality/value

– The present study contributes to the literature as one of the earliest empirical analyses of the performance of highway P3s in the USA. Also, this is one of the first studies to employ frontier analysis methods that focus on the efficiency of highway project delivery.
Beyond virtuality: from engagement platforms to engagement ecosystems
Authors: F. Breidbach Christoph , Brodie Roderick , Hollebeek Linda
Published: October 2014

Purpose

– Understanding the role and implications of information and communication technology (ICT) in service is the key research priority for service science and the management of service quality. The purpose of this paper is to address this priority by providing insights into the role of “engagement platforms” (EPs), physical or virtual customer touch points where actors exchange resources and co-create value. Despite an emerging body of literature that emphasizes the fit between engagement and technology-enabled service contexts, EPs remain ill-defined. Specifically, little is known about the particular types of EPs, their characteristics, and implications for the performance of service ecosystems and managing service quality.

Design/methodology/approach

– By drawing on two illustrative case studies, the authors investigate and theorize about the characteristics and dynamics of EPs in virtual/physical contexts, and identify if, how and to what extent configurations of EPs may enhance resource exchange within and across service ecosystems.

Findings

– By building on emerging research at the service/engagement interface, the paper introduces the notion of the “engagement ecosystem,” as a configuration of individual, mutually dependent EPs that represent specific interactivity-facilitative loci. The paper explicates the relevance of the model and highlight opportunities for future research in this emerging field of inquiry.

Research limitations/implications

– The work addresses the call for research at the intersection of ICT and service science through development and application of the engagement ecosystem concept. The theorizing process draws on two illustrative case studies, and thereby provides a theoretical contribution and foundation for future research in this emerging area.

Practical implications

– The authors guide managerial decision-making regarding the implementation, adoption, and utilization of engagement ecosystems. Furthermore, the nature of “engagement” as a bridging concept implies that the work can help managers to operationalize service-centric thinking.

Originality/value

– By showing how individual EPs form engagement ecosystems, the paper bridges theory and practice, and offers new insight in the realm of practical application of the S-D logic.
The contribution of VSA and SDL perspectives to strategic thinking in emerging economies
Authors: Pels Jaqueline , Barile Sergio , Saviano Marialuisa , Polese Francesco , Carrubbo Luca
Published: October 2014

Purpose

– The purpose of this paper is to reflect upon strategic marketing in emerging economies (EEs). It tries to answer the research question: what new business models are enabled by the Viable Systems Approach (VSA) and Service-Dominant Logic (SDL) perspectives?

Design/methodology/approach

– The paper is developed by integrating two well-established perspectives – VSA and SDL – and applying them to inclusive businesses.

Findings

– The integration of these perspectives allows the authors to recognize a convergence toward business models that seem to be consistent with the principles of inclusive capitalism. The authors claim that by shifting between a reductionist/static and a holistic/dynamic view, these perspectives can be integrated, thus revealing an interesting contribution to the understanding of inclusive business. Specifically, they contribute by highlighting how the economic and social dimensions are intertwined and by highlighting that the management-thinking perspective, which has dominated in recent decades, should shift toward a more inclusive vision.

Research limitations/implications

– The paper represents an attempt to address an inclusive capitalism perspective in the context of marketing. Nevertheless, the conceptual reasoning developed in the paper should be further supported by empirical research carried out in the context of EEs.

Practical implications

– The paper has relevant managerial implications that suggest a rethinking of the business model to market with EEs.

Originality/value

– The paper contributes to the research on inclusive capitalism by linking it to well-grounded conceptual approaches to business that recapture a harmonious relationship between the economy and society.
Impact of Low Birth Weight Child on Maternal Labour Force Participation: Evidence from Taiwan
Authors: Tsou Meng‐Wen , Liu Jin‐Tan , Wang Kuang‐Hsien
Published: October 2014

This paper examines the impact of having a low birth weight child on maternal labour force participation. We use the instrumental variable technique, the sister fixed‐effects model and the propensity score matching method to control for the endogeneity of child health. Using a unique national merged parent–child data set from Taiwan, the within‐sister estimates indicate that having a low birth weight child reduces female employment during the first 3 years after the birth, by 1–2 percentage points. Furthermore, the adverse employment effect is found to be particularly strong for those mothers who have an illegitimate child with low birth weight.
Development of the Arabic Version of the Preschool Activity Card Sort (A‐PACS)
Authors: Malkawi S. H. , Hamed R. T. , Abu‐Dahab S. M. N. , AlHeresh R. A. , Holm M. B.
Published: October 2014

Aim

The purpose of this study is to describe the process of developing the Arabic Version of the Preschool Activity Card Sort (A‐PACS) derived from the Preschool Activity Card Sort (PACS), an internationally recognized tool, which uses parent interview, and photographs of pre‐schoolers engaged in typical activities.

Background

Measuring participation among preschool children in daily activities is an essential part of the evaluation process by occupational therapists, utilizing valid and culturally relevant measurement tools. Given the newness of the occupational therapy profession in the Arab world, a major obstacle is the dearth of measurement tools especially for pre‐schoolers.

Methods

Cultural adaptation of the PACS required a four phase process: collection of culturally appropriate activities using focus groups, translation, cognitive pilot testing and validation using two rounds of ranking (Delphi technique). Caregivers interviewed in all phases of the study included 115 participants. All were recruited from different geographical locations and socio‐economic levels in Jordan, and were stratified by age and gender.

Results

Ninety‐five activities were generated in the final version of the A‐PACS in which 23 were specific to the Arabic culture. The activities were categorized into self‐care (17), community mobility (16), high demand leisure (11), low demand leisure (17), social interaction (15), domestic (8) and education (11). Based on the A‐PACS, the most common five activities of Jordanian children were drinking, walking on stairs, eating a sandwich, gathering with family and kicking a ball.

Conclusion

A culturally adapted Arabic form of the PACS emerged from this investigation. This is the first step in developing a psychometrically sound assessment tool to evaluate participation of Arabic‐speaking preschool children.
Adipose‐derived stem cells incorporated into platelet‐rich plasma improved bone regeneration and maturation in vivo
Authors: Cruz Ariadne Cristiane Cabral , Caon Thiago , Menin Álvaro , Granato Rodrigo , Boabaid Fernanda , Simões Cláudia Maria Oliveira
Published: October 2014

Background/Aim

Some cases of tooth loss related to dental trauma require bone‐grafting procedures to improve the aesthetics before prosthetic rehabilitation or to enable the installation of dental implants. Bone regeneration is often a challenge and could be largely improved by mesenchymal stem cells therapy. However, the appropriate scaffold for these cells still a problem. This study evaluated the in vivo effect of human adipose‐derived stem cells incorporated into autogenous platelet‐rich plasma in bone regeneration and maturation.

Material and methods

Adipose‐derived stem cells were isolated from lipoaspirate tissues and used at passage 4. Immunophenotyping and multilineage differentiation of cells were performed and mesenchymal stem cells characteristics confirmed. Bicortical bone defects (10 mm diameter) were created in the tibia of six beagle dogs to evaluate the effect of adipose‐derived stem cells incorporated into platelet‐rich plasma scaffolds, platelet‐rich plasma alone, autogenous bone grafts, and clot. Samples were removed 6 weeks postsurgeries and analyzed by quantification of primary and secondary bone formation and granulation tissue.

Results

Adipose‐derived stem cells incorporated into platelet‐rich plasma scaffolds promoted the highest bone formation (primary + secondary bone) (P < 0.001), the highest bone maturation (secondary bone) (P < 0.001), and the lowest amount of granulation tissue (P < 0.001).

Conclusions

Adipose‐derived stem cells incorporated into platelet‐rich plasma scaffolds promote more bone formation and maturation, and less granulation tissue in bone defects created in canine tibia. Therefore, platelet‐rich plasma can be considered as a candidate scaffold for adipose‐derived stem cells to promote bone regeneration.
Rapid assessment of a flood‐affected population through a spatial data model
Authors: Raza S.F. , Ahsan M.S. , Ahmad S.R.
Published: October 2014

During humanitarian emergencies, well‐timed information on affected populations is central in planning humanitarian responses and the optimum allocation of available resources. However, this is usually only available following an on‐ground assessment which, in most of the cases, comes too late to contribute to the initial decision‐making process that informs the first wave of humanitarian response. To address this problem, a spatial model was developed for the assessment of the flood‐affected population in a near real‐time scenario. A flood extent vector, extracted from MODerate resolution Imaging Spectro‐radiometer daily images, was superimposed on a LandScan population grid to estimate the population count living in the flooded area, aggregated by their respective administrative level. The methodology was found to be both time‐ and cost‐efficient for riverine floods. The model was tested for its accuracy using an on‐ground initial vulnerability assessment and the figures matched to within 80–90%. This model can be used with a confidence level of ±10% for riverine floods.
Transient renal dysfunction with reversible splenial lesion
Authors: Watanabe Toru , Matsuda Tomoka , Kitagata Ryoichi , Tajima Iwao , Ono Hiroyuki , Hirano Keiko , Shirai Masami , Endoh Akira , Hongo Teruaki
Published: October 2014

We report the case of a 6‐month‐old boy with transient renal dysfunction who had an intensified signal in the splenium of the corpus callosum on magnetic resonance imaging. He presented to hospital with fever and sudden disturbance of consciousness. Cerebrospinal fluid analysis did not show pleocytosis. The mild consciousness disturbance disappeared after 30 min, but the splenial signal persisted even after 8 days. Further, renal glucosuria, increased excretion of select amino acids, and abnormal fractional excretion of electrolytes were observed, indicating renal tubular dysfunction. The abnormal urinary findings spontaneously resolved by day 9 of hospitalization. The splenial lesion took 21 days to normalize. There were no signs of neurological complications 2 months later. This case suggests the possibility of renal involvement in splenial lesions.
Congenital left ventricular aneurysm coexisting with left ventricular non‐compaction in a newborn
Authors: Ootani Katsuki , Shimada Jun , Kitagawa Yosuke , Konno Yuki , Miura Fumitake , Takahashi Toru , Ito Etsuro , Ichinose Kouta , Yonesaka Susumu
Published: October 2014

Described herein is the case of a rare combination of congenital left ventricular (LV) aneurysm and left ventricular non‐compaction (LVNC) in a newborn. The patient developed refractory heart failure soon after birth and died at 5 months of age. The etiology of both congenital LV aneurysm and LVNC seems to be maldevelopment of the ventricular myocardium during early fetal life. Treatment should be individually tailored depending on clinical severity, and treatment options are limited. Given that this combination of congenital LV aneurysm and LVNC is significantly associated with poor prognosis, it appears that patients with congenital LV aneurysm and LVNC are candidates for early, aggressive intervention, including surgical aneurysmectomy and evaluation for transplantation. It is important to be aware of this combination of congenital LV aneurysm and LVNC, and to make earlier decisions on therapeutic strategy.
16q12 microdeletion syndrome in two Japanese boys
Authors: Morisada Naoya , Sekine Takashi , Ishimori Shingo , Tsuda Masahiko , Adachi Masao , Nozu Kandai , Nakanishi Koichi , Tanaka Ryojiro , Iijima Kazumoto
Published: October 2014

Microdeletion of 16q12 is a rare chromosomal abnormality. We present the cases of two Japanese patients with developmental and renal symptoms of differing clinical severity. Both patients had 16q12 interstitial microdeletions that included the entire SALL1 gene. Patient 1 was a 15‐year‐old Japanese boy clinically diagnosed with branchio‐oto‐renal syndrome with mild developmental delay, but with no imperforate anus or polydactyly. Array comparative genome hybridization (aCGH) indicated a 5.2 Mb deletion in 16q12, which included SALL1. Patient 2 was a 13‐year‐old Japanese boy diagnosed with Townes–Brocks syndrome and severe developmental delay, epilepsy, and renal insufficiency requiring renal replacement therapy. Fluorescence in situ hybridization indicated deletion of the entire SALL1 gene. Subsequent aCGH showed a 6 Mb deletion in 16q12q13, which included SALL1. Precise analysis of the present two cases will give us some clues to elucidate the pathogenic mechanisms of 16q12 microdeletion syndrome.
Experimental Study and Numerical Modelling of Creep and Stress Relaxation of Dielectric Elastomers
Authors: Sahu R. , Patra K. , Szpunar J.
Published: October 2014

Dielectric elastomers (DEs) are gaining acceptance as potential actuator materials because of their exhibition of a large amount of deformation when stimulated by electrostatic forces. However, time‐dependent behaviour such as creep and stress relaxation still pose a great challenge for the design, modelling and control of the DE‐based actuators. In this work, attempts are made for experimental estimation and modelling of creep and relaxation properties of one of the most widely used dielectric acrylic elastomers, VHB 4910. Experimental investigation shows that the material possesses strong time‐dependent creep and stress relaxation. It has been shown that creep and stress relaxation characteristics vary with the holding stress and holding strain respectively. Creep and stress relaxation properties are also shown to depend on the number of cycles in the case of cyclic loading. Results also show that Findley's power law can successfully model the creep and stress relaxation behaviour of the VHB 4910 elastomer.
Comparison of an alternative and existing binning methods to reduce the acquisition duration of 4D PET/CT
Authors: Didierlaurent David , Jaudet Cyril , Ribes Sophie , Batatia Hadj , Dierickx Lawrence O. , Zerdoud Slimane , Brillouet Severine , Weyts Kathleen , Courbon Frédéric , Caselles Olivier
Published: October 2014

Purpose:

Respiratory motion is a source of artifacts that reduce image quality in PET. Four dimensional (4D) PET/CT is one approach to overcome this problem. Existing techniques to limiting the effects of respiratory motions are based on prospective phase binning which requires a long acquisition duration (15–25 min). This time is uncomfortable for the patients and limits the clinical exploitation of 4D PET/CT. In this work, the authors evaluated an existing method and an alternative retrospective binning method to reduce the acquisition duration of 4D PET/CT.

Methods:

The authors studied an existing mixed‐amplitude binning (MAB) method and an alternative binning method by mixed‐phases (MPhB). Before implementing MPhB, they analyzed the regularity of the breathing patterns in patients. They studied the breathing signal drift and missing CT slices that could be challenging for implementing MAB. They compared the performance of MAB and MPhB with current binning methods to measure the maximum uptake, internal volume, and maximal range of tumor motion.

Results:

MPhB can be implemented depending on an optimal phase (in average, the exhalation peak phase −4.1% of the entire breathing cycle duration). Signal drift of patients was in average 35% relative to the breathing amplitude. Even after correcting this drift, MAB was feasible in 4D CT for only 64% of patients. No significant differences appeared between the different binning methods to measure the maximum uptake, internal volume, and maximal range of tumor motion. The authors also determined the inaccuracies of MAB and MPhB to measure the maximum amplitude of tumor motion with three bins (less than 3 mm for movement inferior to 12 mm, up to 6.4 mm for a 21 mm movement).

Conclusions:

The authors proposed an alternative binning method by mixed‐phase binning that halves the acquisition duration of 4D PET/CT. Mixed‐amplitude binning was challenging because of signal drift and missing CT slices. They showed that more than three bins were necessary for a more accurate measurement of the maximum amplitude of the tumor motion. However, the current 4D‐CT technology limits the increase of the number of bins in 4D PET/CT because of missing CT slices. One can reconstruct 4D PET images with more bins but without attenuation/scatter correction.
Vampire Selfie: A Curious Case of an Absent Reflection
Authors: Grossman Joshua M.
Published: October 2014

During a recent ride in an elevator, I was startled by an observation. Once the door closed, the features on the back wall of the elevator were evident in a reflection on the door; however, my own reflection appeared absent (see Fig. 1). How could that be? What physics caused this curious phenomenon? The elevator had wooden molding, including horizontal strips that ran all the way around the back and sides (see Fig. 2). These horizontal strips were what showed up most clearly in the reflection. The door's surface was brushed metal with the brush marks all running vertically. Therein lay the solution.
Bridging Physics and Biology Using Resistance and Axons
Authors: Dyer Joshua M.
Published: October 2014

When teaching physics, it is often difficult to get biology-oriented students to see the relevance of physics.1 A complaint often heard is that biology students are required to take physics for the Medical College Admission Test (MCAT) as part of a “weeding out” process, but that they don't feel like they need physics for biology. Despite this impression held by students, there have been calls for better physics education for future physicians and life scientists.2,3 Research is being performed to improve physics classes and labs by linking topics in biology and physics.4,5 Described here is a laboratory experiment covering the topics of resistance of materials and circuits/Kirchhoff's laws in a biology context with their direct application to neurons, axons, and electrical impulse transmission within animals. This experiment will also demonstrate the mechanism believed to cause multiple sclerosis. The apparatus was designed with low-cost and readily available materials in mind.
Grading by Response Category: A simple method for providing students with meaningful feedback on exams in large courses
Authors: Paul Cassandra , Potter Wendell , Weiss Brenda
Published: October 2014

As instructors, we want our students to develop a deep understanding of course material, and feedback is essential in their sense-making process. Providing effective individualized feedback to students in large courses is especially difficult. While researchers suggest,1 and many instructors of large courses are,2,3 incorporating interactive techniques that allow peer feedback, studies have shown that it's important for students to also have direct feedback from the instructor.4 Since the requirement for individualized feedback is difficult to meet during class time in large courses, providing effective feedback on exams and quizzes takes on added importance. Some instructors choose to assess their students using open-ended written exam items that require students to demonstrate their understanding of physics by solving a problem and/or explaining a concept. Because grading these items can be time consuming, the challenge is to develop an approach to grading and provision of feedback that is both efficient and effective.
Teaching Diffraction of Light and Electrons: Classroom Analogies to Classic Experiments
Authors: Velentzas Athanasios
Published: October 2014

Diffraction and interference are phenomena that demonstrate the wave nature of light and of particles. Experiments relating to the diffraction/interference of light can easily be carried out in an educational lab, but it may be impossible to perform experiments involving electrons because of the lack of specialized equipment needed for such experiments. It would, however, be possible for students to analyze data from scientific experiments by analogy to experiments they themselves had performed. Based on this rationale, this paper describes two pairs of experiments that may be of interest to teachers aiming to teach the wave nature of light and of particles to upper secondary school (or to college) students. Specifically, students are asked to (i) carry out a double-slit experiment by using monochromatic light, thus repeating in a way the historical experiment of Young,1 and then analyze real data from Jönsson's2–3 scientific double-slit experiment with electrons, and (ii) perform an experiment involving diffraction of monochromatic light using a compact disc (CD) as a reflection grating, and then by analogy analyze data from the experiment of Davisson and Germer.4 The proposed real experiments are not original, and different versions of them have been wi dely described in the literature.5,6 The educational value of the present work lies in the use of the analogy between experiments carried out in the school lab and experiments performed in the scientific lab.
Modest, reliable spectral peaks in preceding sounds influence vowel perception
Authors: Stilp Christian E. , Anderson Paul W.
Published: October 2014

When a spectral property is reliable across an acoustic context and subsequent vowel target, perception deemphasizes this cue and shifts toward less predictable, more informative cues. This phenomenon (auditory perceptual calibration) has been demonstrated for reliable spectral peaks +20 dB or larger, but psychoacoustic findings predict sensitivity to more modest spectral peaks. Listeners identified vowel targets following a sentence with a reliable +2 to +15 dB spectral peak centered at F2 of the vowel. Vowel identifications weighted F2 significantly less when reliable peaks were at least +5 dB. Results demonstrate high sensitivity to reliable acoustic properties in the sensory environment.
Engineering Acetyl Coenzyme A Supply: Functional Expression of a Bacterial Pyruvate Dehydrogenase Complex in the Cytosol of Saccharomyces cerevisiae
Authors: Kozak Barbara U. , van Rossum Harmen M. , Luttik Marijke A. H. , Akeroyd Michiel , Benjamin Kirsten R. , Wu Liang , de Vries Simon , Daran Jean-Marc , Pronk Jack T. , van Maris Antonius J. A.
Published: October 2014

The energetic (ATP) cost of biochemical pathways critically determines the maximum yield of metabolites of vital or commercial relevance. Cytosolic acetyl coenzyme A (acetyl-CoA) is a key precursor for biosynthesis in eukaryotes and for many industrially relevant product pathways that have been introduced intoSaccharomyces cerevisiae, such as isoprenoids or lipids. In this yeast, synthesis of cytosolic acetyl-CoA via acetyl-CoA synthetase (ACS) involves hydrolysis of ATP to AMP and pyrophosphate. Here, we demonstrate that expression and assembly in the yeast cytosol of an ATP-independent pyruvate dehydrogenase complex (PDH) fromEnterococcus faecaliscan fully replace the ACS-dependent pathway for cytosolic acetyl-CoA synthesis.In vivoactivity ofE. faecalisPDH required simultaneous expression ofE. faecalisgenes encoding its E1α, E1β, E2, and E3 subunits, as well as genes involved in lipoylation of E2, and addition of lipoate to growth media. A strain lacking ACS that expressed theseE. faecalisgenes grew at near-wild-type rates on glucose synthetic medium supplemented with lipoate, under aerobic and anaerobic conditions. A physiological comparison of the engineered strain and an isogenic Acs+reference strain showed small differences in biomass yields and metabolic fluxes. Cellular fractionation and gel filtration studies revealed that theE. faecalisPDH subunits were assembled in the yeast cytosol, with a subunit ratio and enzyme activity similar to values reported for PDH purified fromE. faecalis. This study indicates that cytosolic expression and assembly of PDH in eukaryotic industrial microorganisms is a promising option for minimizing the energy costs of precursor supply in acetyl-CoA-dependent product pathways.

IMPORTANCEGenetically engineered microorganisms are intensively investigated and applied for production of biofuels and chemicals from renewable sugars. To make such processes economically and environmentally sustainable, the energy (ATP) costs for product formation from sugar must be minimized. Here, we focus on an important ATP-requiring process in baker’s yeast (Saccharomyces cerevisiae): synthesis of cytosolic acetyl coenzyme A, a key precursor for many industrially important products, ranging from biofuels to fragrances. We demonstrate that pyruvate dehydrogenase from the bacteriumEnterococcus faecalis, a huge enzyme complex with a size similar to that of a ribosome, can be functionally expressed and assembled in the cytosol of baker’s yeast. Moreover, we show that this ATP-independent mechanism for cytosolic acetyl-CoA synthesis can entirely replace the ATP-costly native yeast pathway. This work provides metabolic engineers with a new option to optimize the performance of baker’s yeast as a “cell factory” for sustainable production of fuels and chemicals.
CD8 T Cells in Innate Immune Responses: Using STAT4-Dependent but Antigen-Independent Pathways to Gamma Interferon during Viral Infection
Authors: Suarez-Ramirez Jenny E. , Tarrio Margarite L. , Kim Kwangsin , Demers Delia A. , Biron Christine A.
Published: October 2014

The cytokine gamma interferon (IFN-γ), with antimicrobial and immunoregulatory functions, can be produced by T cells following stimulation through their T cell receptors (TCRs) for antigen. The innate cytokines type 1 IFNs and interleukin-12 (IL-12) can also stimulate IFN-γ production by natural killer (NK) but not naive T cells. High basal expression of signal transducer and activator of transcription 4 (STAT4), used by type 1 IFN and IL-12 to induce IFN-γ as well as CD25, contributes to the NK cell responses. During acute viral infections, antigen-specific CD8 T cells are stimulated to express elevated STAT4 and respond to the innate factors with IFN-γ production. Little is known about the requirements for cytokine compared to TCR stimulation. Primary infections of mice with lymphocytic choriomeningitis virus (LCMV) demonstrated that although the elicited antigen-specific CD8 T cells acquired STAT4-dependent innate cytokine responsiveness for IFN-γ and CD25 inductionex vivo, TCR stimulation induced these through STAT4-independent pathways. During secondary infections, LCMV-immune CD8 T cells had STAT4-dependent IFN-γ expression at times of innate cytokine induction but subsequently expanded through STAT4-independent pathways. At times of innate cytokine responses during infection with the antigen-distinct murine cytomegalovirus virus (MCMV), NK and LCMV-immune CD8 T cells both had activation of pSTAT4 and IFN-γ. The T cell IFN-γ response was STAT4 and IL-12 dependent, but antigen-dependent expansion was absent. By dissecting requirements for STAT4 and antigen, this work provides novel insights into the endogenous regulation of cytokine and proliferative responses and demonstrates conditioning of innate immunity by experience.

IMPORTANCEUnderstanding the regulation and function of adaptive immunity is key to the development of new and improved vaccines. Its CD8 T cells are activated through antigen-specific receptors to contribute to long-lasting immunity after natural infections or purposeful immunization. The antigen-receptor pathway of stimulation can lead to production of gamma interferon (IFN-γ), a cytokine having both direct antimicrobial and immunoregulatory functions. Natural killer cells can also produce IFN-γ in response to the innate cytokines type 1 IFNs and/or interleukin-12. This work demonstrates that CD8 T cells acquire parallel responsiveness to innate cytokine signaling for IFN-γ expression during their selection and development and maintain this capability to participate in innate immune responses as long-lived memory cells. Thus, CD8 T cells are conditioned to play a role in innate immunity, and their presence under immune conditions has the potential to regulate resistance to either secondary challenges or primary infections with unrelated agents.
Ethnic variations in five lower gastrointestinal diseases: Scottish Health and Ethnicity Linkage Study
Authors: Bhopal Raj S , Cezard Genevieve , Bansal Narinder , Ward Hester J T , Bhala Neeraj
Published: October 2014

Objectives

Our objective was to augment the limited evidence mainly from local, clinical studies of ethnic differences in gastrointestinal disorders. Our question was: are there ethnic variations in hospitalisation/death for lower gastrointestinal disorders in Scotland?

Setting

Scotland.

Population

This retrospective-cohort linked 4.65 (of 4.9) million people in the 2001 census of Scotland (providing data on ethnicity, country of birth and indicators of socioeconomic deprivation) to 9 years of National Health Service hospitalisation and death records.

Primary and secondary outcome measures and analysis

For appendicitis, we studied all ages; for irritable bowel syndrome, ulcerative colitis, Crohn's disease and diverticular disease, we included those ≥20 years. Using Poisson regression (robust variance) we calculated, by ethnic group and sex, first-hospitalisation/death age-adjusted rates per 100 000 person-years, and relative risks (RRs) with 95% CIs multiplied by 100, so the White Scottish reference population had an RR=100.

Results

There were ethnic variations; for example, for irritable bowel syndrome, RRs (95% CIs) were comparatively high in Other White British women (128.4 (111.0 to 148.6)), and low in Pakistani women (75.1 (60.6 to 93.1)). For appendicitis, RRs were high in men in Other White British (145.2 (127.8 to 164.9)), and low in most non-White groups, for example, Pakistanis (73.8 (56.9 to 95.6)). For ulcerative colitis, RRs were high in Indian (169.8 (109.7 to 262.7)) and Pakistani (160.8 (104.2 to 248.2)) men. For Crohn's disease, the RR was high in Pakistani men (209.2 (149.6 to 292.6)). For diverticular disease, RRs were high in Irish men (176.0 (156.9 to 197.5)), and any Mixed background women (144.6 (107.4 to 194.8)), and low in most non-White groups, for example, Chinese men (47.1 (31.0 to 71.6) and women (46.0 (30.4 to 69.8)).

Conclusions

Appendicitis and diverticular disease were comparatively low in most non-White groups, while ulcerative colitis and Crohn's disease were mostly higher in South Asians. Describing and understanding such patterns may help clinical practice and research internationally.
Geographic and temporal variation in the trophic ecology of a small-bodied shark: evidence of resilience to environmental change
Authors: Munroe Samantha E.M. , Heupel Michelle R. , Fisk Aaron T. , Simpfendorfer Colin A.
Published: October 2014

Shark dietary patterns can determine how they will respond to changes in prey availability and biodiversity. Geographic variation in diet can also indicate if species have unique structuring roles or feeding strategies in different environments. Unfortunately, little is known about the diet of most shark species and how diet varies over time and space. This study used stable isotope analysis to assess the diet of the Australian sharpnose shark (Rhizoprionodon taylori). Plasma and muscle δ13C and δ15N of R. taylori were compared with δ13C and δ15N baselines from multiple embayments to determine the isotopic niche, trophic position, and benthic and pelagic contributions to diet over time and space. Overall, R. taylori had a wide trophic position range and consumed prey from benthic and pelagic sources. However, there was geographic and temporal variation in trophic position and benthic and pelagic contributions. These findings indicate R. taylori is a dietary generalist, but different populations may have unique effects on distinct ecosystems. Geographic variation in diet also suggests R. taylori may be adaptive to changes in prey availability.
Genotyping of Methicillin ResistantStaphylococcus aureusStrains Isolated from Hospitalized Children
Authors: Ben Nejma Mouna , Merghni Abderrahmen , Mastouri Maha
Published: October 2014

Community associated methicillin resistantStaphylococcus aureus(CA-MRSA) is an emerging pathogen increasingly reported to cause skin and soft tissue infections for children. The emergence of highly virulencet CA-MRSA strains in the immunodeficiency of young children seemed to be the basic explanation of the increased incidence of CA-MRSA infections among this population. The subjects of this study were 8 patients hospitalized in the Pediatric Department at the University Hospital of Monastir. The patients were young children (aged from 12 days to 18 months) who were suffering from MRSA skin infections; two of them had the infections within 72 h of their admission. The isolates were classified as community isolates as they all carried the staphylococcal cassette chromosomemec(SCCmec) IV andpvlgenes. Epidemiological techniques, pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST), were applied to investigate CA-MRSA strains. Analysis of molecular data revealed that MRSA strains were related according to PFGE patterns and they belonged to a single clone ST80. Antimicrobial susceptibility tests showed that all strains were resistant to kanamycin and 2 strains were resistant to erythromycin.
Dissociative Disorders: Between Neurosis and Psychosis
Authors: Devillé C. , Moeglin C. , Sentissi O.
Published: October 2014

Dissociative disorders are a set of disorders defined by a disturbance affecting functions that are normally integrated with a prevalence of 2.4 percent in industrialised countries. These disorders are often poorly diagnosed or misdiagnosed because of sharing common clinical features with psychotic disorders, but requiring a very different trajectory of care. Repeated clinical situations in a crisis centre in Geneva provided us with a critical overview of current evidence of knowledge in clinical and etiopathological field about dissociative disorders. Because of their multiple expressions and the overlap with psychotic disorders, we focused on the clinical aspects using three different situations to better understand their specificity and to extend our thinking to the relevance of terms “neurosis” and “psychosis.” Finally, we hope that this work might help physicians and psychiatrists to become more aware of this complex set of disorders while making a diagnosis.
Mathematical Modelling of the Spread and Control of Onchocerciasis in Tropical Countries: Case Study in Nigeria
Authors: Oguoma Ikechukwu Chiwueze , Acho Thomas Mbah
Published: October 2014

Onchocerciasis, also known as river blindness and Robles disease, is a parasitic disease caused byOnchocerca volvulus, a nematode (roundworm), and it is endemic in tropical countries like Nigeria. The objective of this paper is to discuss the mathematical formulation underpinning the spread and control of this disease on one hand. On the other hand, we make use of some new analytical methods to derive the solution of the resulting set of equations. The numerical results are presented to test the efficiency and the accuracy of both methods. The techniques used for solving these problems are friendly, very easy, and less time consuming. The numerical solutions in both cases display the biological behaviour of the real life situation.