High fidelity simulations of ion trajectories in miniature ion traps using the boundary-element method

In this paper we present numerical modeling results for endcap and linear ion traps, used for experiments at the National Physical Laboratory in the UK and Innsbruck University respectively. The secular frequencies for Strontium-88 and Calcium-40 ions were calculated from ion trajectories, simulated using boundary-element and finite-difference numerical methods. The results were compared against experimental measurements. Both numerical methods showed high accuracy with boundary-element method being more accurate. Such simulations can be useful tools for designing new traps and trap arrays. They can also be used for obtaining precise trapping parameters for desired ion control when no analytical approach is possible as well as for investigating the ion heating rates due to thermal electronic noise.Comment: 6 pages, 5 figures, changes made to the text according to the editor's and referee's comment

Optimised quadrupole mass spectrometer with a dual filter analyser for in-field chemical sniffing of volatile organic compounds

We report a novel portable 17 kg system based on a quadrupole mass spectrometer (QMS) with an electronic power consumption of 24 W. The system can be used for the in-field identification of gases and volatile/semivolatile organic compounds (VOCs/SVOCs). The mass analyser is a custom-made quadrupole mass filter with a Brubaker pre-filter that gives a mass range of m/z 1-500. It is an upgrade of the previous m/z 1-200 range triple filter analyser system. Analyser design was optimized using 3D numerical simulations as a performance trade-off between single and triple filter designs while maintaining high sensitivity and ease of integration. This also required enhanced design of the electronic control unit (ECU) compared to the previous triple filter ECU designs with lower power consumption, size, weight and cost of the overall system. Another major ECU improvement includes high stability of DC voltage control and ultra-low RF drift, which is important for in-field applications that require stable mass peaks for reliable quantitative analysis and continuous monitoring. Experimental results are presented for the perfluorotributylamine (PFTBA) calibrant and acetone to assess the functionality of the instrument. Performance comparison between the dual and triple filter quadrupole analysers has also been done. Mass spectra are given for methyl benzoate (cocaine simulant), piperidine (phencyclidine simulant), cyclohexanone (C4 simulant) and 2-nitrotoluene (TNT simulant) to assess potential capability for the identification of threat compounds. All spectral results show good correlation with the NIST library mass spectra with unit resolution obtained for spectral peaks within a m/z 1-400 mass range

A Systematic Literature Review of Nursing Interventions for Postpartum Depression and their Outcomes

Purpose: This study was conducted to bring together studies on the common nursing interventions for postpartum depression (PPD) and their outcomes. It aims to provide interpretation of relevant findings to help further enhance the nursing care of patients with postpartum depression. Design and Methods: A systematic literature review (SLR) approach was utilized to synthesize studies related to the management of postpartum depression and its outcomes. One hundred five studies (105) were initially retrieved from three online databases. Eventually, fifteen studies were included in this review after the screening process on quality and risk of bias assessments. Codes were identified from the included studies and were clustered into themes. Athematic map was formulated to visualize the interconnections of the nursing interventions for postpartum depression and its outcomes. Findings: Nurses caring for patients with postpartum depression usually practice PPD education, perinatal assessment, PPD counseling, nurse-delivered psychotherapy, providing social support, drug administration, complementary and alternative therapy combined with conventional management, and patient referral. These nursing practices for postpartum depression yielded the following outcomes: (1) symptom alleviation, (2) empowerment, (3) positive feedback, and (4) negative outcomes. Conclusions and Recommendations: There is a range of nursing interventions for postpartum depression. This review highlights the significant roles of PPD education and nursing assessment and emphasizes these interventions to be practiced not only after childbirth but also during the prenatal period to identify at-risk patients and provide early intervention. This review also emphasizes the need for more coordinated care and a multidisciplinary approach, including patient referral, to achieve better outcomes in the care of postpartum depression patients. This relates to the acknowledgment of the various factors contributing to the development of postpartum depression and its lack of clear etiology

Overview of the Optomechanical Design of the LUVOIR Instruments

The Large Ultraviolet/Optical/Infrared Surveyor (LUVOIR) is a space telescope being submitted for review to the 2020 Decadal Survey in Astronomy and Astrophysics. Its science objectives include both direct imaging and spectral characterization of habitable exoplanets around sun-like stars, the study of planet, star, and galaxy formation, the transfer of matter between different galaxies, and the remote sensing of objects within the Solar System. Two architectures have been designed: a 15 m diameter on-axis telescope (LUVOIR-A) and an 8 m off-axis telescope (LUVOIR-B). This paper discusses the opto-mechanical design of the three LUVOIR instruments: the High Definition Imager (HDI), the LUVOIR UV Multi-object Spectrograph (LUMOS), and the Extreme Coronagraph for Living Planetary Systems (ECLIPS). For both the LUVOIR-A and LUVOIR-B variants of each instrument, optical design specifications are presented including first-order constraints, packaging requirements, and optical performance metrics. These factors are used to illustrate the final design of each instrument and LUVOIR as a whole. In addition to the optical designs, mechanical models are presented for each instrument showing the optical mounts, mechanisms, support structure, etc

Models of everywhere revisited: a technological perspective

The concept ‘models of everywhere’ was first introduced in the mid 2000s as a means of reasoning about the environmental science of a place, changing the nature of the underlying modelling process, from one in which general model structures are used to one in which modelling becomes a learning process about specific places, in particular capturing the idiosyncrasies of that place. At one level, this is a straightforward concept, but at another it is a rich multi-dimensional conceptual framework involving the following key dimensions: models of everywhere, models of everything and models at all times, being constantly re-evaluated against the most current evidence. This is a compelling approach with the potential to deal with epistemic uncertainties and nonlinearities. However, the approach has, as yet, not been fully utilised or explored. This paper examines the concept of models of everywhere in the light of recent advances in technology. The paper argues that, when first proposed, technology was a limiting factor but now, with advances in areas such as Internet of Things, cloud computing and data analytics, many of the barriers have been alleviated. Consequently, it is timely to look again at the concept of models of everywhere in practical conditions as part of a trans-disciplinary effort to tackle the remaining research questions. The paper concludes by identifying the key elements of a research agenda that should underpin such experimentation and deployment

How Thermal Evolution and Mass Loss Sculpt Populations of Super-Earths and Sub-Neptunes: Application to the Kepler-11 System and Beyond

We use models of thermal evolution and XUV-driven mass loss to explore the composition and history of low-mass low-density transiting planets. We investigate the Kepler-11 system in detail and provide estimates of both the current and past planetary compositions. We find that a H/He atmosphere on Kepler-11b is highly vulnerable to mass loss. By comparing to formation models, we show that in situ formation of the system is unlikely. Instead we propose that it is a water-rich system of sub-Neptunes that migrated from beyond the snow line. For the broader population of observed planets, we show that there is a threshold in bulk planet density and incident flux above which no low-mass transiting planets have been observed. We suggest that this threshold is due to the instability of H/He atmospheres to XUV-driven mass loss. Importantly, we find that this flux-density threshold is well reproduced by our thermal evolution/contraction models that incorporate a standard mass loss prescription. Treating the planets' contraction history is essential because the planets have significantly larger radii during the early era of high XUV fluxes. Over time low mass planets with H/He envelopes can be transformed into water-dominated worlds with steam atmospheres or rocky super-Earths. Finally, we use this threshold to provide likely minimum masses and radial velocity amplitudes for the general population of Kepler candidates. Likewise, we use this threshold to provide constraints on the maximum radii of low-mass planets found by radial velocity surveys.Comment: 17 pages, 7 figures. Accepted for publication in ApJ. Compared to the submitted version we made modest modifications to our mass loss model including reducing our default mass loss efficiency. However, the central conclusions of the paper are unchange

Refining the accuracy of validated target identification through coding variant fine-mapping in type 2 diabetes.

We aggregated coding variant data for 81,412 type 2 diabetes cases and 370,832 controls of diverse ancestry, identifying 40 coding variant association signals (P < 2.2 × 10-7); of these, 16 map outside known risk-associated loci. We make two important observations. First, only five of these signals are driven by low-frequency variants: even for these, effect sizes are modest (odds ratio ≤1.29). Second, when we used large-scale genome-wide association data to fine-map the associated variants in their regional context, accounting for the global enrichment of complex trait associations in coding sequence, compelling evidence for coding variant causality was obtained for only 16 signals. At 13 others, the associated coding variants clearly represent 'false leads' with potential to generate erroneous mechanistic inference. Coding variant associations offer a direct route to biological insight for complex diseases and identification of validated therapeutic targets; however, appropriate mechanistic inference requires careful specification of their causal contribution to disease predisposition