2,266 research outputs found

    Measurement Error in Performance Studies of Health Information Technology: Lessons from the Management Literature

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    Just as researchers and clinicians struggle to pin down the benefits attendant to health information technology (IT), management scholars have long labored to identify the performance effects arising from new technologies and from other organizational innovations, namely the reorganization of work and the devolution of decision-making authority. This paper applies lessons from that literature to theorize the likely sources of measurement error that yield the weak statistical relationship between measures of health IT and various performance outcomes. In so doing, it complements the evaluation literature’s more conceptual examination of health IT’s limited performance impact. The paper focuses on seven issues, in particular, that likely bias downward the estimated performance effects of health IT. They are 1.) negative self-selection, 2.) omitted or unobserved variables, 3.) mis-measured contextual variables, 4.) mismeasured health IT variables, 5.) lack of attention to the specific stage of the adoption-to-use continuum being examined, 6.) too short of a time horizon, and 7.) inappropriate units-of-analysis. The authors offer ways to counter these challenges. Looking forward more broadly, they suggest that researchers take an organizationally-grounded approach that privileges internal validity over generalizability. This focus on statistical and empirical issues in health IT-performance studies should be complemented by a focus on theoretical issues, in particular, the ways that health IT creates value and apportions it to various stakeholders

    The Spatial Structure of Stimuli Shapes the Timescale of Correlations in Population Spiking Activity

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    Throughout the central nervous system, the timescale over which pairs of neural spike trains are correlated is shaped by stimulus structure and behavioral context. Such shaping is thought to underlie important changes in the neural code, but the neural circuitry responsible is largely unknown. In this study, we investigate a stimulus-induced shaping of pairwise spike train correlations in the electrosensory system of weakly electric fish. Simultaneous single unit recordings of principal electrosensory cells show that an increase in the spatial extent of stimuli increases correlations at short (~10 ms) timescales while simultaneously reducing correlations at long (~100 ms) timescales. A spiking network model of the first two stages of electrosensory processing replicates this correlation shaping, under the assumptions that spatially broad stimuli both saturate feedforward afferent input and recruit an open-loop inhibitory feedback pathway. Our model predictions are experimentally verified using both the natural heterogeneity of the electrosensory system and pharmacological blockade of descending feedback projections. For weak stimuli, linear response analysis of the spiking network shows that the reduction of long timescale correlation for spatially broad stimuli is similar to correlation cancellation mechanisms previously suggested to be operative in mammalian cortex. The mechanism for correlation shaping supports population-level filtering of irrelevant distractor stimuli, thereby enhancing the population response to relevant prey and conspecific communication inputs. © 2012 Litwin-Kumar et al

    Anti-tuberculosis IgG antibodies as a marker of active mycobacterium tuberculosis disease

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    ManuscriptAnti-Mycobacterium tuberculosis IgG antibodies may aid in the diagnosis of active M. tuberculosis disease. We studied whether anti-M. tuberculosis IgG antibodies are elevated in active M. tuberculosis disease and assessed factors contributing to false positive and negative results. A retrospective study of 2,150 individuals tested by the QuantiFERON-TB Gold In-Tube (QFT-GIT) assay was conducted at University of Utah, ARUP Laboratories, November 2008 to December 2010. All samples were tested with the InBios Active TbDetect™anti-TB IgG antibody assay. Of 1,044 patients with a positive QFT-GIT, 59 (5.7%) were positive for M. tuberculosis antibodies. Fourteen of 1,106 (1.3%) with a negative or indeterminate QFT-GIT were positive for M. tuberculosis antibodies. M. tuberculosis antibody tests were positive in 61.5% with confirmed active M. tuberculosis disease and other mycobacterial infections. Over half of the false negative M. tuberculosis antibody tests occurred in patients ≥ 90 years of age. False positives were seen in 12.9% of autoimmune patients. The odds ratio of being 36 positive on the QFT-GIT and the InBios TB IgG assay increased with confirmed M. tuberculosis disease or highly suspected M. tuberculosis disease and was 86.7 (95% 38 confidence interval [CI], 34.4-218.5) in these two groups when compared to patients negative on both tests. Although anti-M. tuberculosis antibodies can be detected in patients with active M. tuberculosis disease, caution should be used in patients where immunoglobulin levels may be decreased or in patients with autoantibodies

    Ducks and Decoys: Revisiting the Exit-Voice-Loyalty Framework in Assessing the Impact of a Workplace Dispute Resolution System

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    Until now, empirical research has been unable to reliably identify the impact of organizational dispute resolution systems (DRSs) on the workforce at large, in part because of the dearth of data tracking employee perceptions pre- and post- implementation. This study begins to fill this major gap by exploiting survey data from a single, geographically-expansive, US firm with well over 100,000 employees in over a thousand locations. The research design allows us to examine employment relations and human resource (HR) measures, namely, perceptions of justice, organizational commitment, and perceived legal compliance, in the same locations before and after the implementation of a typical, multistep DRS that begins with informal reporting to local managers and culminates with mandatory arbitration. Even after holding all time-constant, location-level variables in place, we find that introduction of the DRS is associated with elevated perceptions of informal procedural justice and interactive justice, but diminished perceptions of formal procedural justice. We also find no discernible effect on organizational commitment, but a significant boost to perceived legal compliance by the company, raising important questions about the tradeoff between voice and exit and formal versus informal aspects of dispute resolution mechanisms.

    Ducks and Decoys: Revisiting the Exit-Voice-Loyalty Framework in Assessing the Impact of a Workplace Dispute Resolution System

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    Until now, empirical research has been unable to reliably identify the impact of organizational dispute resolution systems (DRSs) on the workforce at large, in part because of the dearth of data tracking employee perceptions pre- and post- implementation. This study begins to fill this major gap by exploiting survey data from a single, geographically-expansive, US firm with well over 100,000 employees in over a thousand locations. The research design allows us to examine employment relations and human resource (HR) measures, namely, perceptions of justice, organizational commitment, and perceived legal compliance, in the same locations before and after the implementation of a typical, multistep DRS that begins with informal reporting to local managers and culminates with mandatory arbitration. Even after holding all time-constant, location-level variables in place, we find that introduction of the DRS is associated with elevated perceptions of informal procedural justice and interactive justice, but diminished perceptions of formal procedural justice. We also find no discernible effect on organizational commitment, but a significant boost to perceived legal compliance by the company, raising important questions about the tradeoff between voice and exit and formal versus informal aspects of dispute resolution mechanisms.

    A Note on The Influence of Soil Parent Material on Northern Red OAK Specific Gravity

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    Soil parent material was found to affect the specific gravity of northern red oak wood (Quercus rubra L.). The unextracted specific gravity of wood grown on limestone soils was 0.597 and that of wood grown on sandstone soils was 0.581. Site quality within a soil type had no significant effect. The relationship was independent of both rate of growth and latewood percentage

    Microwave Electronics

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    Contains reports on three research projects.Lincoln Laboratory (Purchase Order DDL-B222)United States Department of the ArmyUnited States Department of the NavyUnited States Department of the Air Force (Contract AF19(604)-5200

    Microvascular System of the Human Fetal Inner Ear: A Scanning Electron Microscopic Study of Corrosion Casts

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    The vascular system of the inner ear was investigated in 18-21 weeks old human fetuses, using the corrosion cast technique in scanning electron microscopy. At that developmental stage, vascularization of the cochlea and semicircular canals shows a pattern very similar to that described for adults. The most important differences which can be regarded as fetal features include: (1) denser limbus vessels, (2) the marginal vessels of the spiral lamina appearing as irregular network which shows a less clear arcade-like arrangement, (3) some radiating arterioles of the spiral lamina and marginal vessels possessing connections with the vascular system of the external wall, and (4) a dense, sinusoidal network of draining venules at scala tympani. These features apparently disappear during the final remodelling of the inner ear microvasculature in the last trimester

    The structure of acquired aural cholesteatoma as revealed by scanning electron microscopy

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    The structural features of cells, their surfaces and the extracellular matrix were investigated in acquired aural cholesteatoma. Cholesteatomas surgically removed from 30 patients were examined by a scanning electron microscope (SEM). The predominant part of a cholesteatoma was composed of stratified squamous epithelium, showing extensive chaotic desquamation. The surface sculpture of the keratinocytes and corneocytes varied from parallel ridges, irregular microplicae and mirovilli, to flat grooves and pits and a completely smooth surface. Sheetlike lamellar structures, probably representing an intercellular lipid-forming permeability barrier, were also observed. Small crystals located in the perimatrix were observed in one case. According to the SEM observations, cholesteatoma epithelium is characterised by abnormal and uncoordinated keratinisation, with a predominance of the advanced stages of the process. Folia Morphol 2008; 67: 8–12
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