Dynamics of fluctuations in a fluid below the onset of Rayleigh-B\'enard convection

We present experimental data and their theoretical interpretation for the decay rates of temperature fluctuations in a thin layer of a fluid heated from below and confined between parallel horizontal plates. The measurements were made with the mean temperature of the layer corresponding to the critical isochore of sulfur hexafluoride above but near the critical point where fluctuations are exceptionally strong. They cover a wide range of temperature gradients below the onset of Rayleigh-B\'enard convection, and span wave numbers on both sides of the critical value for this onset. The decay rates were determined from experimental shadowgraph images of the fluctuations at several camera exposure times. We present a theoretical expression for an exposure-time-dependent structure factor which is needed for the data analysis. As the onset of convection is approached, the data reveal the critical slowing-down associated with the bifurcation. Theoretical predictions for the decay rates as a function of the wave number and temperature gradient are presented and compared with the experimental data. Quantitative agreement is obtained if allowance is made for some uncertainty in the small spacing between the plates, and when an empirical estimate is employed for the influence of symmetric deviations from the Oberbeck-Boussinesq approximation which are to be expected in a fluid with its density at the mean temperature located on the critical isochore.Comment: 13 pages, 10 figures, 52 reference

Astroparticle Physics with a Customized Low-Background Broad Energy Germanium Detector

The MAJORANA Collaboration is building the MAJORANA DEMONSTRATOR, a 60 kg array of high purity germanium detectors housed in an ultra-low background shield at the Sanford Underground Laboratory in Lead, SD. The MAJORANA DEMONSTRATOR will search for neutrinoless double-beta decay of 76Ge while demonstrating the feasibility of a tonne-scale experiment. It may also carry out a dark matter search in the 1-10 GeV/c^2 mass range. We have found that customized Broad Energy Germanium (BEGe) detectors produced by Canberra have several desirable features for a neutrinoless double-beta decay experiment, including low electronic noise, excellent pulse shape analysis capabilities, and simple fabrication. We have deployed a customized BEGe, the MAJORANA Low-Background BEGe at Kimballton (MALBEK), in a low-background cryostat and shield at the Kimballton Underground Research Facility in Virginia. This paper will focus on the detector characteristics and measurements that can be performed with such a radiation detector in a low-background environment.Comment: Submitted to NIMA Proceedings, SORMA XII. 9 pages, 4 figure

PASS: a component of Desk Top PA for the WIPP

There is a growing recognition internationally of the need to demonstrate comprehensiveness in order to build confidence in performance assessments (PAs) for radioactive waste disposal projects. This has resulted in a number of methodologies being developed to formalize the process of defining and documenting the decision basis that underlies a PA. Such methodologies include process influence diagrams and the rock engineering system (RES) matrix. However, these methodologies focus mainly on the conceptualization of the disposal system and do not provide a ready framework to document the decisions behind the model development and parameterization of the PA system. The Performance Assessment Support System (PASS) is a flexible electronic tool designed to increase the transparency and traceability of decision making in the entire PA process. An application of PASS has been developed for the Waste Isolation Pilot Plant (WIPP) where it forms an important component of Desk Top PA, a PC-based PA computational environment under development at Sandia National Laboratories to document, plan, and support management decisions and to assess performance for the WIPP recertification process. This desk-top PA environment is also aimed at providing scientifically-based decision support for assessing the performance of nuclear and hazardous waste management and environmental clean-up systems

Perspectives of patients, nurses, and nephrologists about electronic symptom monitoring with Feedback in hemodialysis care

Available online 25 January 2022RATIONALE & OBJECTIVE: Patients receiving hemodialysis experience high symptom burden and low quality of life (QOL). Electronic patient-reported outcome measures (e-PROMs) monitoring with feedback may be an acceptable intervention to improve health-related QOL for patients receiving hemodialysis. This study explored patient and clinician perspectives on e-PROMs monitoring with feedback. STUDY DESIGN: Qualitative study. SETTING & PARTICIPANTS: 41 participants (12 patients, 13 nephrologists, 16 dialysis nurses) who participated in a 6-month feasibility pilot study of adults receiving facility-based hemodialysis across 4 Australian units. The intervention consisted of electronic symptom monitoring with feedback to clinicians, who also received evidence-based symptom management recommendations to improve health-related QOL. ANALYTICAL APPROACH: Semi-structured interviews and focus group discussions explored the feasibility and acceptability of e-PROMs monitoring with feedback to clinicians. We conducted a thematic analysis of transcripts. RESULTS: We identified 4 themes: enabling efficient, systematic and multidisciplinary patient-centered care; limited data and options for symptom management; requiring familiarity with technology and processes; and barriers and competing priorities. While insufficient patient engagement, logistic/technical challenges and delayed symptom feedback emerged as barriers to implementation, active engagement by nurses in encouraging and supporting patients during survey completion and clinicians' prompt action following symptom feedback were considered to be facilitators to implementation. LIMITATION: Limited generalizability due to inclusion of English-speaking participants only. CONCLUSION: Patients, nurses and nephrologists considered e-PROMs monitoring with feedback to clinicians feasible for symptom management in hemodialysis. Clinician engagement, patient support, reliable technology, timely symptom feedback, and interventions to address symptom burden are likely to improve its implementation within research and clinical settings.Andrea K.Viecelli, Emily Duncanson,, Paul N.Bennett, Matilda D’Antoine, Kathryn Dansie, William Handke ... et al