Versatile ytterbium ion trap experiment for operation of scalable ion-trap chips with motional heating and transition-frequency measurements

We present the design and operation of an ytterbium ion trap experiment with a setup offering versatile optical access and 90 electrical interconnects that can host advanced surface and multilayer ion trap chips mounted on chip carriers. We operate a macroscopic ion trap compatible with this chip carrier design and characterize its performance, demonstrating secular frequencies >1 MHz, and trap and cool nearly all of the stable isotopes, including 171Yb+ ions, as well as ion crystals. For this particular trap we measure the motional heating rate 〈ṅ〉 and observe an 〈ṅ〉∝1/ω2 behavior for different secular frequencies ω. We also determine a spectral noise density SE(1 MHz)=3.6(9)×10-11 V2 m-2 Hz-1 at an ion electrode spacing of 310(10) μm. We describe the experimental setup for trapping and cooling Yb+ ions and provide frequency measurements of the 2S1/2↔2P1/2 and 2D3/2↔3D[3/2]1/2 transitions for the stable 170Yb+, 171Yb+, 172Yb+, 174Yb+, and 176Yb+ isotopes which are more precise than previously published work

Fluorescent microplate-based analysis of protein-DNA interactions II:immobilized DNA

A simple protein-DNA interaction analysis has been developed using both a high-affinity/high-specificity zinc finger protein and a low-specificity zinc finger protein with nonspecific DNA binding capability. The latter protein is designed to mimic background binding by proteins generated in randomized or shuffled gene libraries. In essence, DNA is immobilized onto the surface of microplate wells via streptavidin capture, and green fluorescent protein (GFP)-labeled protein is added in solution as part of a crude cell lysate or protein mixture. After incubation and washing, bound protein is detected in a standard microplate reader. The minimum sensitivity of the assay is approximately 0.4 nM protein. The assay format is ideally suited to investigate the interactions of DNA binding proteins from within crude cell extracts and/or mixtures of proteins that may be encountered in protein libraries generated by codon randomization or gene shuffling

A Multi-Faceted Approach to Enabling Large-Scale Science in a Microsat Constellation

The Polarimeter to UNify the Corona and Heliosphere (PUNCH) mission is a constellation of microsatellites that combines advances in several areas of technology enabling the use of simple imaging instrumentation to measure, to-date, inaccessible aspects of the outer corona and solar wind. The primary PUNCH measurement is brightness and polarization state of light scattered by electrons entrained in solar wind features. This measurement is made possible in the context of a small explorer budget by leveraging a combination of three key elements: (a) a constellation of four small satellites conducting synchronized observations, (b) availability of low-cost off-the-shelf components, and (c) advanced and rigorous science data processing that enables the four microsats to produce 3D images as a single virtual observatory. This paper will discuss the contribution of each of these key enablers, and present the overall status of this NASA Small Explorer mission scheduled for launch in 2025

Associations Between Left Ventricular Dysfunction and Brain Structure and Function: Findings From the SABRE (Southall and Brent Revisited) Study

Background Subclinical left ventricular (LV) dysfunction has been inconsistently associated with early cognitive impairment, and mechanistic pathways have been poorly considered. We investigated the cross‐sectional relationship between LV dysfunction and structural/functional measures of the brain and explored the role of potential mechanisms. Method and Results A total of 1338 individuals (69±6 years) from the Southall and Brent Revisited study underwent echocardiography for systolic (tissue Doppler imaging peak systolic wave) and diastolic (left atrial diameter) assessment. Cognitive function was assessed and total and hippocampal brain volumes were measured by magnetic resonance imaging. Global LV function was assessed by circulating N‐terminal pro–brain natriuretic peptide. The role of potential mechanistic pathways of arterial stiffness, atherosclerosis, microvascular disease, and inflammation were explored. After adjusting for age, sex, and ethnicity, lower systolic function was associated with lower total brain (beta±standard error, 14.9±3.2 cm3; P<0.0001) and hippocampal volumes (0.05±0.02 cm3, P=0.01). Reduced diastolic function was associated with poorer working memory (−0.21±0.07, P=0.004) and fluency scores (−0.18±0.08, P=0.02). Reduced global LV function was associated with smaller hippocampal volume (−0.10±0.03 cm3, P=0.004) and adverse visual memory (−0.076±0.03, P=0.02) and processing speed (0.063±0.02, P=0.006) scores. Separate adjustment for concomitant cardiovascular risk factors attenuated associations with hippocampal volume and fluency only. Further adjustment for the alternative pathways of microvascular disease or arterial stiffness attenuated the relationship between global LV function and visual memory. Conclusions In a community‐based sample of older people, measures of LV function were associated with structural/functional measures of the brain. These associations were not wholly explained by concomitant risk factors or potential mechanistic pathways

An Alternative Interpretation of Recent ARPES Measurements on TiSe2

Recently there has been a renewed interest in the charge density wave transition of TiSe2, fuelled by the possibility that this transition may be driven by the formation of an excitonic insulator or even an excitonic condensate. We show here that the recent ARPES measurements on TiSe2 can also be interpreted in terms of an alternative scenario, in which the transition is due to a combination of Jahn-Teller effects and exciton formation. The hybrid exciton-phonons which cause the CDW formation interpolate between a purely structural and a purely electronic type of transition. Above the transition temperature, the electron-phonon coupling becomes ineffective but a finite mean-field density of excitons remains and gives rise to the observed diffuse ARPES signals.Comment: 4 pages, 2 figure

IDEAL-D Framework for Device Innovation: A Consensus Statement on the Preclinical Stage

OBJECTIVE: To extend the IDEAL Framework for device innovation, IDEAL-D, to include the preclinical stage of development (Stage 0). BACKGROUND: In previous work, the IDEAL collaboration has proposed frameworks for new surgical techniques and complex therapeutic technologies, the central tenet being that development and evaluation can and should proceed together in an ordered and logical manner that balances innovation and safety. METHODS: Following agreement at the IDEAL Collaboration Council, a multidisciplinary working group was formed comprising 12 representatives from healthcare, academia, industry, and a patient advocate. The group conducted a series of discussions following the principles used in the development of the original IDEAL Framework. Importantly, IDEAL aims for maximal transparency, optimal validity in the evaluation of primary effects and minimisation of potential risk to patients or others. The proposals were subjected to further review and editing by members of the IDEAL Council before a final consensus version was adopted. RESULTS: In considering which studies are required before a first-in-human study, we have: (1) classified devices according to what they do and the risks they carry, (2) classified studies according to what they show about the device, and (3) made recommendations based on the principle that the more invasive and high risk a device is, the greater proof required of their safety and effectiveness prior to progression to clinical studies (Stage 1). CONCLUSIONS: The proposed recommendations for preclinical evaluation of medical devices represent a proportionate and pragmatic approach that balances the de-risking of first-in-human translational studies against the benefits of rapid translation of new devices into clinical practice