Explanation in Information Systems

Abstract.  Explanation of observed phenomena is a major objective of both those who conduct and those who apply research in information systems (IS). Whereas explanation based on the statistical relationship between independent and dependent variables is a common outcome of explanatory IS research, philosophers of science disagree about whether statistical relationships are the sole basis for the explanation of phenomena. The purpose of this paper is to introduce an expanded concept of explanation into the realm of IS research. We present a framework based on the four principle explanation types defined in modern philosophy: covering-law explanation, statistical-relevance explanation, contrast-class explanation and functional explanation. A well-established research stream, media richness, is used to illustrate how the different explanation types complement each other in increasing comprehension of the phenomenon. This framework underlies our argument that explanatory pluralism can be used to broaden research perspectives and increase scientific comprehension of IS phenomena above and beyond the methodological and ontological pluralism currently in use in IS research.     

Database Query Processing Using Finite Cursor Machines

We introduce a new abstract model of database query processing, finite cursor machines, that incorporates certain data streaming aspects. The model describes quite faithfully what happens in so-called “one-pass” and “two-pass query processing”. Technically, the model is described in the framework of abstract state machines. Our main results are upper and lower bounds for processing relational algebra queries in this model, specifically, queries of the semijoin fragment of the relational algebra.     

Must "Service With a Smile" Be Stressful? The Moderating Role of Personal Control for American and French Employees.

Suppressing and faking emotional expressions depletes personal resources and predicts job strain for customer-contact employees. The authors argue that personal control over behavior, in the job and within the national culture, provides compensatory resources that reduce this strain. With a survey study of 196 employees from the United States and France, the authors supported that high job autonomy buffered the relationship of emotion regulation with emotional exhaustion and, to a lesser extent, job dissatisfaction. The relationship of emotion regulation with job dissatisfaction also depended on the emotional culture; the relationship was weaker for French customer-contact employees who were proposed to have more personal control over expressions than U.S. employees. Theoretical and research implications for the emotion regulation literature and practical suggestions for minimizing job strain are proposed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Health-related quality of life measured by the SF12 in working populations: Associations with psychosocial work characteristics.

This study investigated the contribution of psychosocial work characteristics (decision latitude, job demand, social support at work, and effort-reward imbalance) to health-related quality of life. Data were derived from 2 aircraft manufacturing plants (N = 1,855) at the start of a longitudinal study. Regression analysis showed that work characteristics (1st model) explained 19% of the variance in the mental summary score of the Short Form-12 Health Survey. R2 change for work characteristics decreased to 13%, accounting for demographics, socioeconomic status, body mass index, and medical condition (5th model). Including health behavior and personality factors (full model), R2 change for work characteristics remained significant. Psychosocial work characteristics account for relevant proportions in the subjective perception of mental health beyond a wide array of medical variables and personality factors. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Pulsed‐Magnetic Hot Joining ‐ New Solutions for Modern Lightweight Structures

To further significantly reduce the car weight, new and innovative production technologies are necessary which allow to join aluminium and – in the future – magnesium profiles. Then it will be possible to connect components made of aluminium or magnesium base alloy with steel parts to one group. Such a new technology is pulsed‐magnetic joining. In order to lower the process forces necessary for pulsed‐magnetic joining of high strength aluminium alloys and in order to establish a technologically useful forming of magnesium alloys, joining at increased temperatures appears to be a viable solution. As part of the research a tool for pulsed‐magnetic hot joining has been developed that combines the processes of heating by induction and pulsed‐magnetic joining. The applicability and the potentials of the tool have been demonstrated with hot joining of aluminium and magnesium profiles. The combination of the techniques allows for the first time to join magnesium profiles with forming by using pulsed‐magnetic forming at high temperatures. Regarding aluminium the combination of the techniques allows a significant reduction of the magnetic pressure that is necessary for the forming process; it thereby increases the operating life of the tools.     

Multimodal Communication in Inhabited Virtual Environments

This paper reports on ongoing research of various aspects of multi-modal interactions in a Virtual Reality environment in which visitors can interact in diverse ways with agents and objects in the environment. The virtual environment is a copy of a theatre and is inhabited by both embodied and non-embodied agents that can assist the visitor: providing information about the performances, selling tickets, or helping the visitor navigate through the building.Interactions in this environment are typically multimodal. Several agents are capable of natural language interactions with the user. However, because the interactions take place in a virtual reality environment, a lot of information can also be presented visually.     

A comparison of the efficacy of stimulus control for medicated and nonmedicated insomniacs

A sample of 21 medicated and 20 nonmedicated insomniacs participated in a sleep medication withdrawal program that provided education about sleep medication and a gradual medication withdrawal schedule. Ten medicated participants received stimulus control treatment and the withdrawal program, and 11 medicated participants served as a control group that received only the withdrawal program. Half of the nonmedicated participants received stimulus control, and the remaining nonmedicated participants served as a wait-list control condition. Medicated participants significantly reduced sleep medication use without significant deterioration on sleep, anxiety, or depression measures from baseline to 8-week follow-up. Stimulus control participants, unlike control group participants, showed significant improvement at follow-up for total sleep time, sleep efficiency, and sleep quality. Stimulus control participants also reported less daytime sleepiness than control participants after treatment. Nonmedicated participants exhibited a more positive response to stimulus control than medicated participants.     

Application of the laryngeal mask for elective percutaneous dilatation tracheotomy

Percutaneous dilatational tracheostomy is an increasingly accepted procedure for bed-side tracheostomy. The exact positioning of the endotracheal tube, the localization of the point for puncturing the trachea and damage to the endotracheal tube and the cuff as well as to the bronchoscope due to the puncturing process are technical problems which can endanger the course of the operation. In a prospective randomized study, we examined whether use of the laryngeal mask airway (LMA) is a real alternative to the endotracheal tube during tracheostomy. Of 48 consecutive patients only 43 fulfilled all criteria for this study: PaO2 > 100 mmHg, PaCO2 < 45 mmHg (in patients with head injury < 35 mmHg) under intermittent positive pressure ventilation (IPPV) with a mean ventilation pressure of < 25 mmHg and an FiO2 of 1.0. Patients with intestinal obstruction, hemorrhages of the mouth and nose and unfavourable anatomic conditions were not included in this study. Three more patients had to be excluded from the study because of technical problems. In 21 patients tracheostomy was performed using an endotracheal tube (ET group) and in 19 patients using a LMA (LM group). After positioning of the endotracheal tube or the LMA, tracheostomy was performed in the usual way. Arterial blood gases (PaO2 and PaCO2) were investigated before positioning of the endotracheal tube or the LMA, five minutes after this procedure and five minutes after the end of tracheostomy. Mean arterial pressure (MAP), heart frequency (HF) and peripheral oxygen saturation (SpO2), endexpiratory CO2 partial pressure (PetCO2) and minute ventilation volume (MVV) were registered every 60 seconds. The ET group and LM group did not differ regarding basic diseases, age and severity of illness. Before the beginning of tracheostomy, there were no differences in MAP, HF, SpO2, PetCO2 and PaCO2 between the two groups. Before tracheostomy, only PaO2 was significantly higher in the LM group than in the ET group. Immediately before the insertion of the tracheal cannula and five minutes after the end of tracheostomy, there were no differences in the measured parameters of the two groups. An increase in PetCO2 and a decrease in minute ventilation volume were observed in both groups. Regarding technical complications, the LMA is a safe alternative to the endotracheal tube. The choice of method should depend on the basic disease and the patient's ventilation requirements at the time of tracheostomy, while there is still a call for safe instruments guaranteeing sufficient sealing of the respiratory tract during the dilatational tracheostomy and simultaneous avoidance of technical problems during puncturing of the trachea and widening of the point of puncturing.     

Alpha2-macroglobulin associates with beta-amyloid peptide and prevents fibril formation

We have used the yeast two-hybrid system to isolate cDNAs encoding proteins that specifically interact with the 42-aa beta-amyloid peptide (Abeta), a major constituent of senile plaques in Alzheimer's disease. The carboxy terminus of alpha2-macroglobulin (alpha2M), a proteinase inhibitor released in response to inflammatory stimuli, was identified as a strong and specific interactor of Abeta, utilizing this system. Direct evidence for this interaction was obtained by co-immunoprecipitation of alpha2M with Abeta from the yeast cell, and by formation of SDS-resistant Abeta complexes in polyacrylamide gels by using synthetic Abeta and purified alpha2M. The association of Abeta with alpha2M and various purified amyloid binding proteins was assessed by employing a method measuring protein-protein interactions in liquid phase. The dissociation constant by this technique for the alpha2M-Abeta association using labeled purified proteins was measured (Kd = 350 nM). Electron microscopy showed that a 1:8 ratio of alpha2M to Abeta prevented fibril formation in solution; the same ratio to Abeta of another acute phase protein, alpha1-antichymotrypsin, was not active in preventing fibril formation in vitro. These results were corroborated by data obtained from an in vitro aggregation assay employing Thioflavine T. The interaction of alpha2M with Abeta suggests new pathway(s) for the clearance of the soluble amyloid peptide.     

Mobilization of the left and right fibrous trigones for relief of severe left ventricular outflow obstruction

BACKGROUND: There is still no agreement about the optimal method of surgical relief of fixed subaortic stenosis, particularly the severe forms. OBJECTIVES: The purpose of this study was to describe a new technique for the relief of subaortic stenosis based on analysis of the functional anatomy of the left ventricular outflow tract and pathophysiologic features of subaortic stenosis. Methods and patients: We propose that one of the basic abnormalities in subaortic stenosis is interference with the hinge mechanism provided by the 2 fibrous trigones with progressive deposition of fibrous tissue in these angles. The technique described in this paper consists of excision of all components of the fibrous "ring," with mobilization of the left and right fibrous trigones. This results in the restoration of the normal dynamic behavior of the left ventricular outflow tract with maximal widening of the outflow tract as the result of backward displacement of the subaortic curtain and anterior leaflet of the mitral valve. This technique has been used in 57 consecutive patients who ranged in age between 5 months and 56 years (mean, 15.5 +/- 10.6 years). Gradients across the left ventricular outflow tract were between 45 and 200 mm Hg (mean, 86.7 mm Hg). Additional lesions were present in 10 patients, and 7 patients had had 8 previous operations on the left ventricular outflow tract. At operation, in addition to resection of subaortic stenosis, 3 patients had aortic valvotomy, 2 patients had homograft replacement of the aortic valve, 7 patients had patch closure of a ventricular septal defect, and 1 patient had open mitral valvotomy. RESULTS: There were 2 early deaths and 1 late sudden death during the follow-up period that ranged from 1 month to 25 years (mean, 15. 2 years). One patient experienced the development of endocarditis on the aortic valve 7 years after operation, which was successfully treated by homograft replacement. Postoperative gradients across the left ventricular outflow tract varied from no gradient to 30 mm Hg (mean, 8 mm Hg). There were no instances of recurrence of a gradient across the left ventricular outflow tract. CONCLUSION: It is concluded that mobilization of the left and right fibrous trigones results in durable relief of subaortic stenosis.