Proton Bunch Self-Modulation in Plasma with Density Gradient

We study experimentally the effect of linear plasma density gradients on the self-modulation of a 400 GeV proton bunch. Results show that a positive or negative gradient increases or decreases the number of microbunches and the relative charge per microbunch observed after 10 m of plasma. The measured modulation frequency also increases or decreases. With the largest positive gradient we observe two frequencies in the modulation power spectrum. Results are consistent with changes in wakefields' phase velocity due to plasma density gradients adding to the slow wakefields' phase velocity during self-modulation growth predicted by linear theory.

High-Precision Determination of Oxygen K_{α} Transition Energy Excludes Incongruent Motion of Interstellar Oxygen

We demonstrate a widely applicable technique to absolutely calibrate the energy scale of x-ray spectra with experimentally well-known and accurately calculable transitions of highly charged ions, allowing us to measure the K-shell Rydberg spectrum of molecular O_{2} with 8 meV uncertainty. We reveal a systematic ∼450  meV shift from previous literature values, and settle an extraordinary discrepancy between astrophysical and laboratory measurements of neutral atomic oxygen, the latter being calibrated against the aforementioned O_{2} literature values. Because of the widespread use of such, now deprecated, references, our method impacts on many branches of x-ray absorption spectroscopy. Moreover, it potentially reduces absolute uncertainties there to below the meV level.

NON-EXCITING WAKEFIELD STRUCTURED BUNCHES IN A ONE-DIMENSIONAL PLASMA MODEL

A model of one-dimensional (1D) cold plasma with an external train of rigidly structured bunches with diverse charges has been introduced. In this model, a solution is presented that cancels the wakefield after the train is found. The density of such bunches can be much greater than the density of the plasma, and a high amplitude electrical field arising inside the train can be used for charged-particle acceleration. In addition, analytical and numerical simulations have been performed.

The ELFIN Mission

The Electron Loss and Fields Investigation with a Spatio-Temporal Ambiguity-Resolving option (ELFIN-STAR, or heretoforth simply: ELFIN) mission comprises two identical 3-Unit (3U) CubeSats on a polar (∼93^∘ inclination), nearly circular, low-Earth (∼450 km altitude) orbit. Launched on September 15, 2018, ELFIN is expected to have a >2.5 year lifetime. Its primary science objective is to resolve the mechanism of storm-time relativistic electron precipitation, for which electromagnetic ion cyclotron (EMIC) waves are a prime candidate. From its ionospheric vantage point, ELFIN uses its unique pitch-angle-resolving capability to determine whether measured relativistic electron pitch-angle and energy spectra within the loss cone bear the characteristic signatures of scattering by EMIC waves or whether such scattering may be due to other processes. Pairing identical ELFIN satellites with slowly-variable along-track separation allows disambiguation of spatial and temporal evolution of the precipitation over minutes-to-tens-of-minutes timescales, faster than the orbit period of a single low-altitude satellite (T_orbit ∼ 90 min). Each satellite carries an energetic particle detector for electrons (EPDE) that measures 50 keV to 5 MeV electrons with Δ E/E < 40% and a fluxgate magnetometer (FGM) on a ∼72 cm boom that measures magnetic field waves (e.g., EMIC waves) in the range from DC to 5 Hz Nyquist (nominally) with <0.3 nT/sqrt(Hz) noise at 1 Hz. The spinning satellites (T_spin ∼ 3 s) are equipped with magnetorquers (air coils) that permit spin-up or -down and reorientation maneuvers. Using those, the spin axis is placed normal to the orbit plane (nominally), allowing full pitch-angle resolution twice per spin. An energetic particle detector for ions (EPDI) measures 250 keV - 5 MeV ions, addressing secondary science. Funded initially by CalSpace and the University Nanosat Program, ELFIN was selected for flight with joint support from NSF and NASA between 2014 and 2018 and launched by the ELaNa XVIII program on a Delta II rocket (with IceSatII as the primary). Mission operations are currently funded by NASA. Working under experienced UCLA mentors, with advice from The Aerospace Corporation and NASA personnel, more than 250 undergraduates have matured the ELFIN implementation strategy; developed the instruments, satellite, and ground systems and operate the two satellites. ELFIN's already high potential for cutting-edge science return is compounded by concurrent equatorial Heliophysics missions (THEMIS, Arase, Van Allen Probes, MMS) and ground stations. ELFIN's integrated data analysis approach, rapid dissemination strategies via the SPace Environment Data Analysis System (SPEDAS), and data coordination with the Heliophysics/Geospace System Observatory (H/GSO) optimize science yield, enabling the widest community benefits. Several storm-time events have already been captured and are presented herein to demonstrate ELFIN's data analysis methods and potential. These form the basis of on-going studies to resolve the primary mission science objective. Broad energy precipitation events, precipitation bands, and microbursts, clearly seen both at dawn and dusk, extend from tens of keV to >1 MeV. This broad energy range of precipitation indicates that multiple waves are providing scattering concurrently. Many observed events show significant backscattered fluxes, which in the past were hard to resolve by equatorial spacecraft or non-pitch-angle-resolving ionospheric missions. These observations suggest that the ionosphere plays a significant role in modifying magnetospheric electron fluxes and wave-particle interactions. Routine data captures starting in February 2020 and lasting for at least another year, approximately the remainder of the mission lifetime, are expected to provide a very rich dataset to address questions even beyond the primary mission science objective.

0614 Diurnal Patterning of Autonomic Measures in Sleep Apnea and Paroxysmal Atrial Fibrillation and Response to Continuous Positive Airway Pressure Therapy

Introduction

Diurnal patterning of autonomic function in paroxysmal atrial fibrillation (PAF) and sleep disordered breathing (SDB) is unknown. We hypothesize heart rate variability (HRV) as surrogates of autonomic function, exhibit diurnal differences in PAF relative to SDB severity and treatment.

Methods

We leveraged the Sleep Apnea and Atrial Fibrillation Biomarkers and Electrophysiologic Atrial Triggers (SAFEBEAT,NCT02576587) study focused on participants with PAF and SDB (apnea hypopnea index,AHI≥15,3% oxygen desaturation hypopnea). Attended 16-channel polysomnography (PSG) and continuous ECG monitoring (Heartrak Telemetry®) for 7-21 days was performed at baseline and after 3-months of continuous positive airway pressure (CPAP). Linear mixed-effects models (least square means,95%CI) were used to assess relationships between daily average HRV measures (frequency domain:LF,HF,LF/HF;time domain:MNN,RMSSD,SD1,SD ratio and novel non-linear:DFA-alpha measures) with SDB (AHI),%sleep time with SaO2&lt;90%(TRT&lt;90): per 5-unit increase),effect of 3-month CPAP relative to sleep-wake and statistical interaction of sleep-wake. Analyses were conducted using SAS version v.9.4, Cary, NC.

Results

The analytic sample was comprised of 33 cases with PAF and SDB:61.1±11.7 years,62.5% male, BMI:33.9±7.2kg/m2,75% Caucasian,AHI 15.1 (IQR: 4.4,29.4) and 68.8% on atrioventricular nodal blocking medications. AHI was associated with frequency (HF:0.08[0.01,0.16] and LF/HF:-0.11[-0.20, -0.01]), time (SD1:0.08[0.02,0.14] and SD ratio: 0.09[0.04,0.14]) and non-linear (DFA-alpha1: -0.02[-0.036,-0.003]) domain measures during wake, but not sleep. Significant sleep-wake and AHI as well as TRT&lt;90 interactions relative to HRV measures were observed (p≤0.001). Only SD ratio was associated with TRT&lt;90 (0.12[0.03,0.24]). Baseline to follow-up CPAP time domain measures were altered mainly during wake versus sleep with MNN increased 0.13: [0.08,0.19],p&lt;0.001; RMSSD increased 0.13 [0.08,0.19], p&lt;0.001; SD1 increased 30% [0.09,0.55], p=0.004; SD ratio increased 20% [0.01,0.43], p=0.033,and also frequency domain: HF increased 33%[0.03,0.72], p=0.028.

Conclusion

SDB defined by AHI--more so than nocturnal hypoxia--was associated with surrogate autonomic measures impacted by CPAP intervention during wake and not sleep in PAF. SDB-related autonomic influences in PAF appear to be more pronounced during wakefulness suggesting long-term potentiation-like influences.

Support

This study was supported by the National Heart, Lung and Blood Institute (NHLBI) [Grant R01 HL108493] and National Institutes of Health (NIH) National Center for Research Resources [Grant UL1 RR024989]

3D brain angiogenesis model to reconstitute functional human blood-brain barrier in vitro

The human central nervous system (CNS) vasculature expresses a distinctive barrier phenotype, the blood-brain barrier (BBB). As the BBB contributes to low efficiency in CNS pharmacotherapy by restricting drug transport, the development of an in vitro human BBB model has been in demand. Here, we present a microfluidic model of CNS angiogenesis having three-dimensional (3D) lumenized vasculature in concert with perivascular cells. We confirmed the necessity of the angiogenic tri-culture system (brain endothelium in direct interaction with pericytes and astrocytes) to attain essential phenotypes of BBB vasculature, such as minimized vessel diameter and maximized junction expression. In addition, lower vascular permeability is achieved in the tri-culture condition compared to the monoculture condition. Notably, we focussed on reconstituting the functional efflux transporter system, including p-glycoprotein (p-gp), which is highly responsible for restrictive drug transport. By conducting the calcein-AM efflux assay on our 3D perfusable vasculature after treatment of efflux transporter inhibitors, we confirmed the higher efflux property and prominent effect of inhibitors in the tri-culture model. Taken together, we designed a 3D human BBB model with functional barrier properties based on a developmentally inspired CNS angiogenesis protocol. We expect the model to contribute to a deeper understanding of pathological CNS angiogenesis and the development of effective CNS medications.

3D brain angiogenesis model to reconstitute functional human blood-brain barrier in vitro

The human central nervous system (CNS) vasculature expresses a distinctive barrier phenotype, the blood-brain barrier (BBB). As the BBB contributes to low efficiency in CNS pharmacotherapy by restricting drug transport, the development of an in vitro human BBB model has been in demand. Here, we present a microfluidic model of CNS angiogenesis having three-dimensional (3D) lumenized vasculature in concert with perivascular cells. We confirmed the necessity of the angiogenic tri-culture system (brain endothelium in direct interaction with pericytes and astrocytes) to attain essential phenotypes of BBB vasculature, such as minimized vessel diameter and maximized junction expression. In addition, lower vascular permeability is achieved in the tri-culture condition compared to the monoculture condition. Notably, we focussed on reconstituting the functional efflux transporter system, including p-glycoprotein (p-gp), which is highly responsible for restrictive drug transport. By conducting the calcein-AM efflux assay on our 3D perfusable vasculature after treatment of efflux transporter inhibitors, we confirmed the higher efflux property and prominent effect of inhibitors in the tri-culture model. Taken together, we designed a 3D human BBB model with functional barrier properties based on a developmentally inspired CNS angiogenesis protocol. We expect the model to contribute to a deeper understanding of pathological CNS angiogenesis and the development of effective CNS medications.

Hierarchies of evidence applied to lifestyle Medicine (HEALM): introduction of a strength-of-evidence approach based on a methodological systematic review

BACKGROUND

Current methods for assessing strength of evidence prioritize the contributions of randomized controlled trials (RCTs). The objective of this study was to characterize strength of evidence (SOE) tools in recent use, identify their application to lifestyle interventions for improved longevity, vitality, or successful aging, and to assess implications of the findings.

METHODS

The search strategy was created in PubMed and modified as needed for four additional databases: Embase, AnthropologyPlus, PsycINFO, and Ageline, supplemented by manual searching. Systematic reviews and meta-analyses of intervention trials or observational studies relevant to lifestyle intervention were included if they used a specified SOE tool. Data was collected for each SOE tool. Conditions necessary for assigning the highest SOE grading and treatment of prospective cohort studies within each SOE rating framework were summarized. The expert panel convened to discuss the implications of findings for assessing evidence in the domain of lifestyle medicine.

RESULTS AND CONCLUSIONS

A total of 15 unique tools were identified. Ten were tools developed and used by governmental agencies or other equivalent professional bodies and were applicable in a variety of settings. Of these 10, four require consistent results from RCTs of high quality to award the highest rating of evidence. Most SOE tools include prospective cohort studies only to note their secondary contribution to overall SOE as compared to RCTs. We developed a new construct, Hierarchies of Evidence Applied to Lifestyle Medicine (HEALM), to illustrate the feasibility of a tool based on the specific contributions of diverse research methods to understanding lifetime effects of health behaviors. Assessment of evidence relevant to lifestyle medicine requires a potential adaptation of SOE approaches when outcomes and/or exposures obviate exclusive or preferential reliance on RCTs. This systematic review was registered with the International Prospective Register of Systematic Reviews, PROSPERO [CRD42018082148].

Proton-driven plasma wakefield acceleration in AWAKE

In this article, we briefly summarize the experiments performed during the first run of the Advanced Wakefield Experiment, AWAKE, at CERN (European Organization for Nuclear Research). The final goal of AWAKE Run 1 (2013-2018) was to demonstrate that 10-20 MeV electrons can be accelerated to GeV energies in a plasma wakefield driven by a highly relativistic self-modulated proton bunch. We describe the experiment, outline the measurement concept and present first results. Last, we outline our plans for the future. This article is part of the Theo Murphy meeting issue 'Directions in particle beam-driven plasma wakefield acceleration'.

A method for profile measurements of small transverse size beams by means of a vibrating wire

A method for profile measurements of small transverse size beams by means of a vibrating wire is proposed. The main idea is to use the vibrating wire motion during its oscillations as a scanning mechanism and synchronously measure the scattered/reflected particles/photons created through the interactions of the measured beam with the wire. The method is expected to be applicable for thin beams in particle accelerators. The proof-of-principle test results, obtained using a laser beam, are presented.

Abstract PD1-12: Omics profiling of CDK4/6 inhibitors reveals functionally important secondary targets of abemaciclib

The recent introduction of small molecule inhibitors of cyclin-dependent kinases (CDK) 4/6 to the clinic has improved the treatment of hormone receptor positive breast cancer, and shown promise in other malignancies. The three clinically used CDK4/6 inhibitors, palbociclib, ribociclib, and abemaciclib, are reported to be broadly similar although recent data suggest that abemaciclib has distinct single-agent activity in patients and a unique adverse effects profile. Key questions are: How do these drugs differ at the molecular level? Should such differences inform their use in the clinic? Can these three agents be used interchangeably or should patient stratification differ between them? We use molecular and functional profiling by mRNA sequencing, mass spectrometry-based proteomics, and GR-based dose-response assays to obtain complementary views of the mechanisms of action of CDK4/6 inhibitors. We show that abemaciclib, but not ribociclib or palbociclib, is a potent inhibitor of kinases other than CDK4/6, including CDK1/Cyclin B, which appears to cause arrest in the G2 phase of the cell cycle, and CDK2/Cyclin E/A, which is implicated in resistance to palbociclib. We show that inhibition of these additional targets is accessible in a xenograft model. Whereas ribociclib and palbociclib induce cytostasis, and cells adapt to these drugs within 2-3 days of exposure, abemaciclib induces cell death and durably blocks cell proliferation. Abemaciclib is active even in retinoblastoma protein (pRb)-deficient cells in which CDK4/6 inhibition by palbociclib or ribociclib is completely ineffective. The degree of polypharmacology of small molecule drugs is increasingly viewed as an important consideration in their design, with implications for efficacy, toxicity, and acquired resistance. In the case of CDK4/6 inhibitors, we propose that abemaciclib polypharmacology elicits unique molecular responses. More generally, we propose that multi-omic approaches are required to fully elucidate the spectrum of targets relevant to drug action in tumor cells. We expect such understanding to assist in stratifying patient populations and ordering sequential therapies when resistance arises.

Citation Format: Mills CE, Hafner M, Subramanian K, Chen C, Chung M, Boswell SA, Everley RA, Walmsley CS, Juric D, Sorger PK. Omics profiling of CDK4/6 inhibitors reveals functionally important secondary targets of abemaciclib [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr PD1-12.

Experimental Observation of Proton Bunch Modulation in a Plasma at Varying Plasma Densities

We give direct experimental evidence for the observation of the full transverse self-modulation of a long, relativistic proton bunch propagating through a dense plasma. The bunch exits the plasma with a periodic density modulation resulting from radial wakefield effects. We show that the modulation is seeded by a relativistic ionization front created using an intense laser pulse copropagating with the proton bunch. The modulation extends over the length of the proton bunch following the seed point. By varying the plasma density over one order of magnitude, we show that the modulation frequency scales with the expected dependence on the plasma density, i.e., it is equal to the plasma frequency, as expected from theory.

Experimental Observation of Plasma Wakefield Growth Driven by the Seeded Self-Modulation of a Proton Bunch

We measure the effects of transverse wakefields driven by a relativistic proton bunch in plasma with densities of 2.1×10^{14} and 7.7×10^{14}  electrons/cm^{3}. We show that these wakefields periodically defocus the proton bunch itself, consistently with the development of the seeded self-modulation process. We show that the defocusing increases both along the bunch and along the plasma by using time resolved and time-integrated measurements of the proton bunch transverse distribution. We evaluate the transverse wakefield amplitudes and show that they exceed their seed value (<15  MV/m) and reach over 300  MV/m. All these results confirm the development of the seeded self-modulation process, a necessary condition for external injection of low energy and acceleration of electrons to multi-GeV energy levels.

Findings from aetiological investigation of Auditory Neuropathy Spectrum Disorder in children referred to cochlear implant programs

OBJECTIVES

Auditory neuropathy spectrum disorder (ANSD) is an audiological diagnosis characterised by hearing dysfunction in the presence of intact outer hair cell function in the cochlea. ANSD is thought to account for 7-10% of all childhood permanent hearing impairment, and can result from a range of pathological processes. This paper describes the rationale, methods and findings from the aetiological investigation of ANSD.

METHODS

Retrospective audit of four cochlear implant programmes.

RESULTS

97 patients were identified. 79% of patients were identified before the age of one. Prematurity and jaundice were the most frequently identified aetiological factors. 33 patients had cochlear nerve deficiency on imaging. Genetic diagnoses identified included otoferlin, SX010 gene, connexin 26 and A1FM1 gene mutations. ANSD was seen in conjunction with syndromes including Kallman syndrome, CHARGE syndrome, X-linked deafness, SOTOS syndrome, Brown Vieletto Van Laere syndrome, and CAPOS syndrome.

DISCUSSION

We present a two-level system of aetiological investigation that is clinically practical. Patients with ANSD sufficiently severe to consider cochlear implantation are generally identified at an early age. Aetiological investigation is important to guide prognosis and identify comorbidity.

CONCLUSION

Prematurity and jaundice are the most commonly identified aetiological factors in ANSD. Imaging findings identify crucial factors in a significant minority. An important minority may have genetic and syndromic diagnoses that require further management.

Trust in Whom? Dioxin, Organizations, Risk Perception, and Fish Consumption in Michigan's Saginaw Bay Watershed

Trust is generally recognized as important for risk-relevant behavior but research suggests that trust in different organizations may have varying effects. This research advances the literature by testing two hypotheses which postulate that this variability can be explained by risk perception. We collected data from 351 anglers regarding their trust in nine organizations whose efforts are relevant to dioxin contamination in Michigan's Saginaw Bay Watershed, risk perceptions, and self-reports of risky behavior (i.e., consumption of local fish identified as especially likely to contain contaminants). As hypothesized (H1), the negative effect of trust in two agencies-the Michigan Department of Natural Resources (MDNR) and a Michigan Department of Health and Human Services-sponsored River Walker Program (RWP)-on risky behavior was significantly mediated by risk perception but these effects differed from each other such that trust in the MDNR was associated with increased perceptions of risk while trust in the RWP was associated with decreased perceptions of benefit. Also as hypothesized (H2), the positive effect of trust in Dow Chemical Company on risky behavior was significantly mediated by risk perception such that increased trust in Dow was associated with reduced risk perception. The current results lend credence to arguments regarding the importance of specificity in the target of trust and advance this literature by suggesting that differential effects on risk perception help explain this variability. Thus, organizations whose efforts focus on risk communication appear ideally situated to reduce risky behavior through a negative impact on risk perception. Other organizations, however, may run the risk of increasing risky behavior if their efforts result in reduced perceptions of risk.

Microfluidic-based vascularized microphysiological systems

Microphysiological systems have emerged in the last decade to provide an alternative to in vivo models in basic science and pharmaceutical research. In the field of vascular biology, in particular, there has been a lack of a suitable in vitro model exhibiting a three-dimensional structure and the physiological function of vasculature integrated with organ-on-a-chip models. The rapid development of organ-on-a-chip technology is well positioned to fulfill unmet needs. Recently, functional integration of vasculature with diverse microphysiological systems has been increasing. This recent trend corresponds to emerging research interest in how the vascular system contributes to various physiological and pathological conditions. This innovative platform has undergone significant development, but adoption of this technology by end-users and researchers in biology is still a work in progress. Therefore, it is critical to focus on simplification and standardization to promote the distribution and acceptance of this technology by the end-users. In this review, we will introduce the latest developments in vascularized microphysiological systems and summarize their outlook in basic research and drug screening applications.