An Experimental and Numerical Investigation of Flow Accelerated FLiBe Corrosion

Renewed interest in molten salt reactor technology has brought to light the need for a better understanding of FLiBe corrosion. To this end a flowing FLiBe corrosion test loop was designed to test the flow effects of FLiBe corrosion. The loop consists of a pump, melt tank, and stainless-steel tubing assembly that heats the molten salt to high temperatures and circulates it over test specimens. The experiment has been constructed and has completed initial shakedown testing. To support the flowing FLiBe experiment, a numerical corrosion model that couples FLiBe electrochemistry, solid metal diffusion, and mass transport was implemented. The model has been successfully validated, and initial results indicate that the addition of nickel protective layers to structural metal will greatly reduce FLiBe corrosion

Waveform control of orientation-dependent ionization of DCl in few-cycle laser fields

Strong few-cycle light fields with stable electric field waveforms allow controlling electrons on time scales down to the attosecond domain. We have studied the dissociative ionization of randomly oriented DCl in 5 fs light fields at 720 nm in the tunneling regime. Momentum distributions of D+ and Cl+ fragments were recorded via velocity-map imaging. A waveformdependent anti-correlated directional emission of D+ and Cl+ fragments is observed. Comparison of our results with calculations indicates that tailoring of the light field via the carrier envelope phase permits the control over the orientation of DCl+ and in turn the directional emission of charged fragments upon the breakup of the molecular ion

Qualitative Comparative Analysis (QCA) In Information Systems Research: Status Quo, Guidelines, and Future Directions

Qualitative comparative analysis (QCA) allows researchers to study how configurations of conditions lead to outcomes and, thereby, richly explain the dynamics of complex digital phenomena. To advance discussion on QCA in the information systems (IS) discipline, we introduce its fundamental concepts and offer guidelines for authors on how to apply QCA to advance IS research. We also provide checklists for reviewers of QCA papers. We illustrate how to apply our guidelines through two exemplar studies. In the first exemplar study, we focus on IT-business strategic alignment to study the influence that different forms of alignment have on firm performance. In the second exemplar study, we use the perspective of the integrated technology acceptance model to explain an individual’s intention to use a digital assistant. The contrasting results from both studies highlight how to use QCA to derive robust and reproducible results. By doing so, we contribute to encouraging IS scholars to use QCA to develop sophisticated models that accurately depict real-world IS phenomena

Epidemiological and clinical features of travel-associated cryptosporidiosis

ABSTRACTData concerning the clinical and epidemiological features of travel-associated cryptosporidiosis are lacking. In order to investigate the impact of this disease on travellers' health, a retrospective study was conducted at the Institute of Tropical Medicine, Berlin. In total, 57 cryptosporidial infections were identified between 2000 and 2004, resulting in a prevalence of 2.9% in patients with travel-associated diarrhoea. Travel to south-central Asia, especially India, was associated with a higher prevalence of infection than was travel to other destinations. Clinically, the disease resembled giardiasis, but fever and arthralgias seemed to occur more frequently

Social Networking Site Use Resumption: A Model of Return Migration

This research explains why individuals resume using social networking sites (SNSs) after terminating their use. Drawing on return migration theory, we developed a theory-driven model of SNS resumption that includes two novel antecedents of SNS resumption behavior: nonuse-related dissatisfaction and use-related satisfaction. We also hypothesize that dispositional resistance to change moderates the impact of nonuse-related dissatisfaction and use-related satisfaction on resumption. We used a mixed methods approach to refine and evaluate the research model. Study 1 used the critical incident method to identify SNS-specific antecedents of nonuse-related satisfaction and use-related satisfaction, allowing us to refine the research model. Study 2 used structural equation modeling to evaluate our research model using two three-wave surveys: one with recent ex-users who recently decided to stop using and delete their profiles on Facebook and one with long-standing ex-users who stopped using and deleted their profiles on Facebook a long time ago. We found support for most relationships in our model: nonuse-related dissatisfaction and use-related satisfaction drive resumption intentions, and dispositional resistance moderates these relationships. Furthermore, we found that the time elapsed since users discontinued Facebook moderated these relationships such that the effect of nonuse-related dissatisfaction on resumption intention is stronger for recent ex-users and the effect of use-related satisfaction is stronger for long-standing ex-users. Our findings advance the understanding of resumption, an understudied behavior of the IT lifecycle and IT use and acceptance research

Novel Nonreciprocal Acoustic Effects in Antiferromagnets

The possible occurrence of nonreciprocal acoustic effects in antiferromagnets in the absence of an external magnetic field is investigated using both (i) a microscopic formulation of the magnetoelastic interaction between spins and phonons and (ii) symmetry arguments. We predict for certain antiferromagnets the existence of two new nonreciprocal (non-time invariant) effects: A boundary-condition induced nonreciprocal effect and the occurrence of transversal phonon modes propagating in opposite directions having different velocities. Estimates are given and possible materials for these effects to be observed are suggested.Comment: Euro. Phys. Lett. (in press

Systemic Thrombolytic Therapy Alone and in Combination with Mechanical Revascularization in Acute Ischemic Stroke in Two Children

Thrombolytic therapy is not recommended for acute ischemic stroke (AIS) in patients under the age of 18 and published experience is limited. In this case report, we describe two children treated with systemic thrombolytic therapy. One child received additional mechanical revascularization and achieved a good clinical outcome. The differences in the fibrinolytic system and the different etiology of AIS in childhood may limit a simple extrapolation of the adult guidelines for systemic thrombolytic therapy. Acute multimodal imaging to clarify the etiology of AIS might help to select the most appropriate treatment modality

Analysis of novel geometry-independent method for dialysis access pressure-flow monitoring

Abstract Background End-stage renal disease (ESRD) confers a large health-care burden for the United States, and the morbidity associated with vascular access failure has stimulated research into detection of vascular access stenosis and low flow prior to thrombosis. We present data investigating the possibility of using differential pressure (ΔP) monitoring to estimate access flow (Q) for dialysis access monitoring, with the goal of utilizing micro-electro-mechanical systems (MEMS) pressure sensors integrated within the shaft of dialysis needles. Methods A model of the arteriovenous graft fluid circuit was used to study the relationship between Q and the ΔP between two dialysis needles placed 2.5–20.0 cm apart. Tubing was varied to simulate grafts with inner diameters of 4.76–7.95 mm. Data were compared with values from two steady-flow models. These results, and those from computational fluid dynamics (CFD) modeling of ΔP as a function of needle position, were used to devise and test a method of estimating Q using ΔP and variable dialysis pump speeds (variable flow) that diminishes dependence on geometric factors and fluid characteristics. Results In the fluid circuit model, ΔP increased with increasing volume flow rate and with increasing needle-separation distance. A nonlinear model closely predicts this ΔP-Q relationship (R2 > 0.98) for all graft diameters and needle-separation distances tested. CFD modeling suggested turbulent needle effects are greatest within 1 cm of the needle tip. Utilizing linear, quadratic and combined variable flow algorithms, dialysis access flow was estimated using geometry-independent models and an experimental dialysis system with the pressure sensors separated from the dialysis needle tip by distances ranging from 1 to 5 cm. Real-time ΔP waveform data were also observed during the mock dialysis treatment, which may be useful in detecting low or reversed flow within the access. Conclusion With further experimentation and needle design, this geometry-independent approach may prove to be a useful access flow monitoring method.http://deepblue.lib.umich.edu/bitstream/2027.42/112774/1/12976_2008_Article_178.pd