Using the Case Survey Method for Synthesizing Case Study Evidence in Information Systems Research

A common characteristic of the IS discipline is that the bulk of the empirical evidence is embodied in case studies. However, the ever-growing body of case based evidence also constitutes a major challenge to the IS discipline. Although each case study may provide rich insights into specific phenomena, it is difficult to generalize on the basis of single-N or small-N case studies. What IS research would benefit from is a method that allows for the quantitative inquiry of the vast amount of primarily qualitative case studies. The purpose of this paper is to introduce the case survey method as new mode of inquiry to supplement the rich repertoire of IS review methods. Therefore, we show how the case survey method is embedded in the landscape of review methods used in IS research and what its principal stages, techniques, limitations and potentials are

Case Survey Studies in Software Engineering Research

Background: Given the social aspects of Software Engineering (SE), in the last twenty years, researchers from the field started using research methods common in social sciences such as case study, ethnography, and grounded theory. More recently, case survey, another imported research method, has seen its increasing use in SE studies. It is based on existing case studies reported in the literature and intends to harness the generalizability of survey and the depth of case study. However, little is known on how case survey has been applied in SE research, let alone guidelines on how to employ it properly. Aims: This article aims to provide a better understanding of how case survey has been applied in Software Engineering research. Method: To address this knowledge gap, we performed a systematic mapping study and analyzed 12 Software Engineering studies that used the case survey method. Results: Our findings show that these studies presented a heterogeneous understanding of the approach ranging from secondary studies to primary inquiries focused on a large number of instances of a research phenomenon. They have not applied the case survey method consistently as defined in the seminal methodological papers. Conclusions: We conclude that a set of clearly defined guidelines are needed on how to use case survey in SE research, to ensure the quality of the studies employing this approach and to provide a set of clearly defined criteria to evaluate such work.Comment: Accepted for presentation at ACM / IEEE International Symposium on Empirical Software Engineering and Measurement (ESEM) (ESEM '20

Elevated photic response is followed by a rapid decay and depressed state in ictogenic networks

Objective: The switch between nonseizure and seizure states involves profound alterations in network excitability and synchrony. In this study, we aimed to identify and compare features of neural excitability and dynamics across multiple zebrafish seizure and epilepsy models. Methods: Inspired by video-electroencephalographic recordings in patients, we developed a framework to study spontaneous and photically evoked neural and locomotor activity in zebrafish larvae, by combining high-throughput behavioral tracking and whole-brain in vivo two-photon calcium imaging. Results: Our setup allowed us to dissect behavioral and physiological features that are divergent or convergent across multiple models. We observed that spontaneous locomotor and neural activity exhibit great diversity across models. Nonetheless, during photic stimulation, hyperexcitability and rapid response dynamics were well conserved across multiple models, highlighting the reliability of photically evoked activity for high-throughput assays. Intriguingly, in several models, we observed that the initial elevated photic response is often followed by rapid decay of neural activity and a prominent depressed state. Elevated photic response and following depressed state in seizure-prone networks are significantly reduced by the antiseizure medication valproic acid. Finally, rapid decay and depression of neural activity following photic stimulation temporally overlap with slow recruitment of astroglial calcium signals that are enhanced in seizure-prone networks. Significance: We argue that fast decay of neural activity and depressed states following photic response are likely due to homeostatic mechanisms triggered by excessive neural activity. An improved understanding of the interplay between elevated and depressed excitability states might suggest tailored epilepsy therapies. Keywords: astroglia; calcium imaging; depressed state; elevated state; epilepsy; high-throughput behavior; hyperexcitability; photic stimulation; seizure; zebrafis

Prolonged Graft Survival in Older Recipient Mice Is Determined by Impaired Effector T-Cell but Intact Regulatory T-Cell Responses

Elderly organ transplant recipients represent a fast growing segment of patients on the waiting list. We examined age-dependent CD4+ T-cell functions in a wild-type (WT) and a transgenic mouse transplant model and analyzed the suppressive function of old regulatory T-cells. We found that splenocytes of naïve old B6 mice contained significantly higher frequencies of T-cells with an effector/memory phenotype (CD4+CD44highCD62Llow). However, in-vitro proliferation (MLR) and IFNγ-production (ELISPOT) were markedly reduced with increasing age. Likewise, skin graft rejection was significantly delayed in older recipients and fewer graft infiltrating CD4+T-cells were observed. Old CD4+ T-cells demonstrated a significant impaired responsiveness as indicated by diminished proliferation and activation. In contrast, old alloantigen-specific CD4+CD25+FoxP3+ T-cells demonstrated a dose-dependent well-preserved suppressor function. Next, we examined characteristics of 18-month old alloreactive T-cells in a transgenic adoptive transfer model. Adoptively transferred old T-cells proliferated significantly less in response to antigen. Skin graft rejection was significantly delayed in older recipients, and graft infiltrating cells were reduced. In summary, advanced recipient age was associated with delayed acute rejection and impaired CD4+ T-cell function and proliferation while CD4+CD25+FoxP3+ T-cells (Tregs) showed a well-preserved function

Evaluierung der Perspektiven der Ölmühlenverfahrenstechnik mit den Schwerpunkten Energiebedarf und Emissionsvermeidung

The perspectives of oil milling technology have been evaluated with respect to the minimization of energy demand and emission rates (CO2-, hexane). Based on the computer modelling of the current oil milling process, steps like dehulling and extrusion are introduced in the process line. Characteristical data like energy consumption divided in electric and thermal energy, CO2-equivalent-emission, hexane-emission of various process lines have been computed. An optimization of heat flow has been performed with reference to the pinch technology. The energy demand of an oil mill, which process dehulled rape seeds could be generated by the thermal utilization of the hulls. In comparison to existing plants a reduction in process energy demand of 20 % can be predicted for the optimized oil milling process. Because of the energy generation using the hulls the CO2-emission is changed drastically. Existing plants emit 237 kg CO2-equivalent-emission per ton oil because of the consumption fossil ene rgy resources. Whereas the optimized plant could produce more electric and thermal energy as it needs. Therefore assuming new energy generation process negative value of 262 kg CO2-equivalent could be computed

Using Case Survey Methodology to Extract Variables and Causal Links: An Example from Studying Business Process Change

Business process change (BPC) projects are complex initiatives with many interrelated factors that still cause unforeseen delays and even cancellations. While research on BPC provides useful insights into successes and failures of BPC projects, we argue that these insights remain rather fragmented. We present a multi-method approach to create a coherent picture by extracting variables and causal links within BPC projects. We do so by adopting case survey methodology and causal loop diagrams. We show the usefulness of this approach by analyzing and consolidating insights of 130 BPC case studies. We make two main contributions: (1) we show the potential of system dynamics in BPC research by integrating the fragmented research on BPC to achieve more coherent picture, and (2) we contribute to the literature on qualitative methods used in system dynamics, as we propose to use case survey methodology for developing causal loop diagrams

Loss of glutamate transporter eaat2a leads to aberrant neuronal excitability, recurrent epileptic seizures, and basal hypoactivity

Astroglial excitatory amino acid transporter 2 (EAAT2, GLT-1, and SLC1A2) regulates the duration and extent of neuronal excitation by removing glutamate from the synaptic cleft. Hence, an impairment in EAAT2 function could lead to an imbalanced brain network excitability. Here, we investigated the functional alterations of neuronal and astroglial networks associated with the loss of function in the astroglia predominant eaat2a gene in zebrafish. We observed that eaat2a-/- mutant zebrafish larvae display recurrent spontaneous and light-induced seizures in neurons and astroglia, which coincide with an abrupt increase in extracellular glutamate levels. In stark contrast to this hyperexcitability, basal neuronal and astroglial activity was surprisingly reduced in eaat2a-/- mutant animals, which manifested in decreased overall locomotion. Our results reveal an essential and mechanistic contribution of EAAT2a in balancing brain excitability, and its direct link to epileptic seizures. Keywords: astroglia; brain excitability; calcium imaging; eaat2; epilepsy; glutamate; zebrafish