The expected background spectrum in NaI dark matter detectors and the DAMA result

Detailed Monte Carlo simulations of the expected radioactive background rates and spectra in NaI crystals are presented. The obtained spectra are then compared to those measured in the DAMA/NaI and DAMA/LIBRA experiments. The simulations can be made consistent with the measured DAMA spectrum only by assuming higher than reported concentrations of some isotopes and even so leave very little room for the dark matter signal. We conclude that any interpretation of the annual modulation of the event rate observed by DAMA as a dark matter signal, should include full consideration of the background spectrum. This would significantly restrict the range of dark matter models capable of explaining the modulation effect.Comment: 17 pages, 6 figure

Narrow muon bundles from muon pair production in rock

We revise the process of muon pair production by high-energy muons in rock using the recently published cross-section. The three-dimensional Monte Carlo code MUSIC has been used to obtain the characteristics of the muon bundles initiated via this process. We have compared them with those of conventional muon bundles initiated in the atmosphere and shown that large underground detectors, capable of collecting hundreds of thousands of multiple muon events, can discriminate statistically muon induced bundles from conventional ones. However, we find that the enhancement of the measured muon decoherence function over that predicted at small distances, recently reported by the MACRO experiment, cannot be explained by the effect of muon pair production alone, unless its cross-section is underestimated by a factor of 3.Comment: 10 pages, 1 table, 2 figures, to be published in Physics Letters

Measurement of the Scintillation Efficiency of Na Recoils in NaI(Tl) down to 10 keV Nuclear Recoil Energy relevant to Dark Matter Searches

We present preliminary results of measurements of the quenching factor for Na recoils in NaI(Tl) at room temperature, made at a dedicated neutron facility at the University of Sheffield. Measurements have been performed with a 2.45 MeV mono-energetic neutron generator in the energy range from 10 keV to 100 keV nuclear recoil energy. A BC501A liquid scintillator detector was used to tag neutrons. Cuts on pulse-shape discrimination from the BC501A liquid scintillator detector and neutron time-of-flight were performed on pulses recorded by a digitizer with a 2 ns sampling time. Measured quenching factors range from 19% to 26%, in agreement with other experiments. From pulse-shape analysis, a mean time of pulses from electron and nuclear recoils are compared down to 2 keV electron equivalent energy.Comment: to appear in Proc. 6th Int. Workshop on the Identification of Dark Matter, 11-16 September 2006, Rhodes, Greece; 6 pages, 4 figures; corrected preliminary theoretical estimation curve plotted in figure

Retrograde transport pathways utilised by viruses and protein toxins

A model has been presented for retrograde transport of certain toxins and viruses from the cell surface to the ER that suggests an obligatory interaction with a glycolipid receptor at the cell surface. Here we review studies on the ER trafficking cholera toxin, Shiga and Shiga-like toxins, Pseudomonas exotoxin A and ricin, and compare the retrograde routes followed by these protein toxins to those of the ER trafficking SV40 and polyoma viruses. We conclude that there is in fact no obligatory requirement for a glycolipid receptor, nor even with a protein receptor in a lipid-rich environment. Emerging data suggests instead that there is no common pathway utilised for retrograde transport by all of these pathogens, the choice of route being determined by the particular receptor utilised

Anion transport across varying lipid membranes – the effect of lipophilicity

The anion transport properties of a range of alkyl-substituted phenylthioureas were tested in vesicles of different lipid composition. Although changes in the bilayer affected the rate of transport for all compounds in the series, the ‘ideal’ log P for peak activity did not change depending on the composition of the bilayers tested

Limits on WIMP Dark Matter

The current state searches for dark matter in the form of Weakly Interacting Massive Particles (WIMPs) using both direct and indirect techniques is reviewed. Advances in recent years by various direct search experiments, utilising technology able to record the nuclear recoil events expected from elastic scattering by WIMPs, have allowed progress towards lower limits to be made. In particular, the Edelweiss and CDMS collaborations are achieving sensitiviy able to challenge data from DAMA interpreted as evidence for WIMPs of mass in the region of 60 GeV. Meanwhile, indirect searches, based on observing the annihilation products of neutralino-neutralino interactions in the Earth, Sun and Galaxy, have produced intriguing results. For instance, analysis by Superkamiokande now suggests limits comparable with the best direct search results.Comment: 8 pages, 5 figures, International Europhysics Conference on High Energy Physic

Barriers and facilitators to the implementation of an evidence-based electronic minimum dataset for nursing team leader handover: A descriptive survey

© 2017 Australian College of Critical Care Nurses Ltd. Introduction: There is widespread use of clinical information systems in intensive care units however, the evidence to support electronic handover is limited. Objectives: The study aim was to assess the barriers and facilitators to use of an electronic minimum dataset for nursing team leader shift-to-shift handover in the intensive care unit prior to its implementation. Methods: The study was conducted in a 21-bed medical/surgical intensive care unit, specialising in cardiothoracic surgery at a tertiary referral hospital, in Queensland, Australia. An established tool was modified to the intensive care nursing handover context and a survey of all 63 nursing team leaders was undertaken. Survey statements were rated using a 6-point Likert scale with selections from 'strongly disagree' to 'strongly agree', and open-ended questions. Descriptive statistics were used to summarise results. Results and discussion: A total of 39 team leaders responded to the survey (62%). Team leaders used general intensive care work unit guidelines to inform practice however they were less familiar with the intensive care handover work unit guideline. Barriers to minimum dataset uptake included: a tool that was not user friendly, time consuming and contained too much information. Facilitators to minimum dataset adoption included: a tool that was user friendly, saved time and contained relevant information. Identifying the complexities of a healthcare setting prior to the implementation of an intervention assists researchers and clinicians to integrate new knowledge into healthcare settings. Conclusion: Barriers and facilitators to knowledge use focused on usability, content and efficiency of the electronic minimum dataset and can be used to inform tailored strategies to optimise team leaders' adoption of a minimum dataset for handover

Using the Plan-Do-Study-Act cycle to manage interruptions during nursing team leader handover in the intensive care unit: Quality improvement project

Introduction: Intensive care unit (ICU) nursing team leader (TL) handover is a process that is at risk for miscommunication, compromising patient safety. Interruptions during this process have the potential to increase miscommunication. Bedside handover and use of a structured handover tool are two strategies advocated internationally to improve safety of handover. Study objectives: This quality improvement project employed the Plan-Do-Study-Act (PDSA) cycle to improve handover processes during nursing TL handover, including to reduce interruptions post-implementation of a multidimensional strategy. Methods: The project was conducted in a 21-bed adult medical/surgical ICU, at a tertiary referral hospital, in Queensland, Australia. All TLs were invited to participate, with consent provided to observe and record process details of handover. Baseline data indicated that TLs experienced frequent interruptions during handover. An audit of the source and reason interruptions occurred informed the development of an intervention that included education sessions focussed on safe handover practices, hands on training using an evidence-based electronic minimum dataset to discuss patient information and the relocation of handovers from the central ICU desk to the bedside. Data were analysed using descriptive statistics (median, IQR, frequency and percentages). Results: Handovers during the baseline period (n = 40) were conducted at the central desk and attracted 64 interruptions, equivalent to one interruption every 23 min. After implementation of the improvement strategy (n = 49 handovers), 52 interruptions occurred at the bedside, equivalent to one interruption every 29 min. During both the baseline period and post-intervention nurses were the main source to interrupt handovers to exchange greetings with the TL and to discuss patient and organisational updates. Conclusion: The PDSA provided a structure to understand the problem, develop an improvement strategy and inform future work to effectively manage interruptions during nursing TL handover