Rethinking the Concept of IT Use

The information systems (IS) community has developed many theories, approaches, and models that identify conditions and determinants of successful IT use. However, each model in the IS literature has evolved to address specific aspects and dimensions. This has led to conflicting results concerning the impact of IT use. Consequently, while a rich body of knowledge has emerged, with prominent models such as the Technology Acceptance Model or the IS Success Model, the complexity of defining a suitable multi-dimensional construct for IT use has largely been neglected. In this paper, we develop a new causal model of IT use. Based on Adaptive Structuration Theory, we argue for the multi-dimensionality of IT use and thoroughly derive its components. Moreover, we introduce two new concepts into studies of successful IT use: functional affordance and symbolic expression. Both establish a relation between the IT system in investigation and its users. In doing so, we provide a novel, synthesized approach for investigating IT use in the context of the IS Success Model and the framework of Adaptive Structuration Theory

Information Systems Change and Social Interaction: A Research Agenda

As the investments in IT are still growing and organizations are more dependent on IT than ever before practitioners as well as researchers are still lacking theories or models that help and explain if and when IT has to be adapted, partly exchanged or entirely implemented. In this paper we claim that one major reason for IS change lies in the interaction of human agents while using IT to solve tasks. Human agents cooperate within and simultaneously build a social network that is partly selforganizing, dynamic and uncontrollable from the outside. This dynamic can cause unintended pressure on the use and the usability of IT and therefore may force organizations to change the IS. This article discusses the Structurational Model of IT and concepts of the Social Network Analysis and draws several implications of examining the impact of social interaction on IS change

RECONCEPTUALIZING IT USE IN THE POST-ADOPTIVE CONTEXT

The information systems (IS) community has developed many theories, approaches, and models that identify conditions and determinants of successful IT use. However, each model in the IS literature has evolved to address specific aspects and dimensions. This has led to conflicting results concerning the impact of IT use. Consequently, while a rich body of knowledge has emerged, with prominent models such as the Technology Acceptance Model or the IS Success Model, the complexity of defining a suitable multi-dimensional construct for IT use has largely been neglected. In this paper, we develop a new causal model of IT use. Based on Adaptive Structuration Theory, we argue for the multidimensionality of IT use and thoroughly derive its components. Moreover, we introduce two new concepts into studies of successful IT use: functional affordance and symbolic expression. Both establish a relation between the IT system under investigation and its users. In doing so, we provide a novel, synthesized approach for investigating IT use in the context of post-adoptive behaviours and the framework of Adaptive Structuration Theory

piRNAclusterDB 2.0: update and expansion of the piRNA cluster database.

PIWI-interacting RNAs (piRNAs) and their partnering PIWI proteins defend the animal germline against transposable elements and play a crucial role in fertility. Numerous studies in the past have uncovered many additional functions of the piRNA pathway, including gene regulation, anti-viral defense, and somatic transposon repression. Further, comparative analyses across phylogenetic groups showed that the PIWI/piRNA system evolves rapidly and exhibits great evolutionary plasticity. However, the presence of so-called piRNA clusters as the major source of piRNAs is common to nearly all metazoan species. These genomic piRNA-producing loci are highly divergent across taxa and critically influence piRNA populations in different evolutionary lineages. We launched the initial version of the piRNA cluster database to facilitate research on regulation and evolution of piRNA-producing loci across tissues und species. In recent years the amount of small RNA sequencing data that was generated and the abundance of species that were studied has grown rapidly. To keep up with this recent progress, we have released a major update for the piRNA cluster database (https://www.smallrnagroup.uni-mainz.de/piRNAclusterDB), expanding it from 12 to a total of 51 species with hundreds of new datasets, and revised its overall structure to enable easy navigation through this large amount of data

The Impact of Functional Affordances and Symbolic Expressions on the Formation of Beliefs

Research on IS success and IT adoption has shown that object-based beliefs about IT systems have a profound impact on subsequent IT usage. However, we still lack knowledge on and need to identify antecedents and determinants of object-based beliefs in order to understand how the belief formation process works and how it can be influenced. Our research builds on and extends Markus and Silver’s (2008) concepts of functional affordance and symbolic expression to examine how IT-related factors influence the formation of beliefs. To test our research model, we surveyed 183 users of a student information system. The proposed model was supported, offering evidence that values, meaning, and functional affordances provided by an IT system positively affect information quality and system quality

Local orthorhombicity in the magnetic C4C_4 phase of the hole-doped iron-arsenide superconductor Sr1−x_{1-x}Nax_{x}Fe2_2As2_2

We report temperature-dependent pair distribution function measurements of Sr$_{1-x}$Na$_{x}$Fe$_2$As$_2$, an iron-based superconductor system that contains a magnetic phase with reentrant tetragonal symmetry, known as the magnetic $C_4$ phase. Quantitative refinements indicate that the instantaneous local structure in the $C_4$ phase is comprised of fluctuating orthorhombic regions with a length scale of $\sim$2 nm, despite the tetragonal symmetry of the average static structure. Additionally, local orthorhombic fluctuations exist on a similar length scale at temperatures well into the paramagnetic tetragonal phase. These results highlight the exceptionally large nematic susceptibility of iron-based superconductors and have significant implications for the magnetic $C_4$ phase and the neighboring $C_2$ and superconducting phases

Primate piRNA cluster evolution suggests limited relevance of pseudogenes in piRNA-mediated gene regulation

PIWI proteins and their guiding Piwi-interacting (pi-) RNAs direct the silencing of target nucleic acids in the animal germline and soma. Although in mammal testes fetal piRNAs are involved in extensive silencing of transposons, pachytene piRNAs have additionally been shown to act in post-transcriptional gene regulation. The bulk of pachytene piRNAs is produced from large genomic loci, named piRNA clusters. Recently, the presence of reversed pseudogenes within piRNA clusters prompted the idea that piRNAs derived from such sequences might direct regulation of their parent genes. Here, we examine primate piRNA clusters and integrated pseudogenes in a comparative approach to gain a deeper understanding about mammalian piRNA cluster evolution and the presumed gene-regulatory role of pseudogene-derived piRNAs. Initially, we provide a broad analysis of the evolutionary relationships of piRNA clusters and their differential activity among six primate species. Subsequently, we show that pseudogenes in reserve orientation relative to piRNA cluster transcription direction generally do not exhibit signs of selection pressure and cause weakly conserved targeting of homologous genes among species, suggesting a lack of functional constraints and thus only a minor significance for gene regulation in most cases. Finally, we report that piRNA-producing loci generally tend to be located in active genomic regions with elevated gene and pseudogene density. Thus, we conclude that the presence of most pseudogenes in piRNA clusters might be regarded as a byproduct of piRNA cluster generation, whereas this does not exclude that some pseudogenes nevertheless play critical roles in individual cases

Increased Hepato-Splanchnic Vasoconstriction in Diabetics during Regular Hemodialysis

BACKGROUND AND OBJECTIVES:Ultrafiltration (UF) of excess fluid activates numerous compensatory mechanisms during hemodialysis (HD). The increase of both total peripheral and splanchnic vascular resistance is considered essential in maintaining hemodynamic stability. The aim of this study was to evaluate the extent of UF-induced changes in hepato-splanchnic blood flow and resistance in a group of maintenance HD patients during regular dialysis. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS:Hepato-splanchnic flow resistance index (RI) and hepato-splanchnic perfusion index (QI) were measured in 12 chronic HD patients using a modified, non-invasive Indocyaningreen (ICG) dilution method. During a midweek dialysis session we determined RI, QI, ICG disappearance rate (kICG), plasma volume (Vp), hematocrit (Hct), mean arterial blood pressure (MAP) and heart rate (HR) at four times in hourly intervals (t1 to t4). Dialysis settings were standardized and all patient studies were done in duplicate. RESULTS:In the whole study group mean UF volume was 1.86 ± 0.46 L, Vp dropped from 3.65 ± 0.77L at t1 to 3.40 ± 0.78L at t4, and all patients remained hemodynamically stable. In all patients RI significantly increased from 12.40 ± 4.21 mmHg∙s∙m2/mL at t1 to 14.94 ± 6.36 mmHg∙s∙m2/mL at t4 while QI significantly decreased from 0.61 ± 0.22 at t1 to 0.52 ± 0.20 L/min/m2 at t4, indicating active vasoconstriction. In diabetic subjects, however, RI was significantly larger than in non-diabetics at all time points. QI was lower in diabetic subjects. CONCLUSIONS:In chronic HD-patients hepato-splanchnic blood flow substantially decreases during moderate UF as a result of an active splanchnic vasoconstriction. Our data indicate that diabetic HD-patients are particularly prone to splanchnic ischemia and might therefore have an increased risk for bacterial translocation, endotoxemia and systemic inflammation

Clinical Impact of Atrial Fibrillation in Patients with Pulmonary Hypertension

BACKGROUND: Pulmonary hypertension (PH) is associated with progressive impairment of right ventricular function, reduced exercise capacity and a poor prognosis. Little is known about the prevalence, clinical manifestation and impact of atrial fibrillation (AF) on cardiac function in PH. METHODS: In a four year single-centre retrospective analysis 225 patients with confirmed PH of various origins were enrolled to investigate the prevalence of AF, and to assess the clinical manifestation, 6-minute walk distance, NT-proBNP levels, echocardiographic parameters and hemodynamics obtained by right heart catheterization in PH with AF. RESULTS: AF was prevalent in 31.1%. In patients with PH and AF, parameters of clinical deterioration (NYHA/WHO functional class, 6-minute walk distance, NT-proBNP levels) and renal function were significantly compromised compared to patients with PH and sinus rhythm (SR). In the total PH cohort and in PH not related to left heart disease occurrence of AF was associated with an increase of right atrial pressure (RAP) and right atrial dilatation. While no direct association was found between pulmonary artery pressure (PAP) and AF in these patients, right ventricular function was reduced in AF, indicating more advanced disease. In PH due to left heart failure the prevalence of AF was particularly high (57.7% vs. 23.1% in other forms of PH). In this subgroup, left atrial dilatation, increase of pulmonary capillary wedge pressure, PAP and RAP were more pronounced in AF than in SR, suggesting that more marked backward failure led to AF in this setting. CONCLUSION: PH is associated with increased prevalence of AF. Occurrence of AF in PH indicates clinical deterioration and more advanced disease