Achievement of Target Gain Larger than Unity in an Inertial Fusion Experiment

On December 5, 2022, an indirect drive fusion implosion on the National Ignition Facility (NIF) achieved a target gain G_{target} of 1.5. This is the first laboratory demonstration of exceeding "scientific breakeven" (or G_{target}>1) where 2.05 MJ of 351 nm laser light produced 3.1 MJ of total fusion yield, a result which significantly exceeds the Lawson criterion for fusion ignition as reported in a previous NIF implosion [H. Abu-Shawareb et al. (Indirect Drive ICF Collaboration), Phys. Rev. Lett. 129, 075001 (2022)PRLTAO0031-900710.1103/PhysRevLett.129.075001]. This achievement is the culmination of more than five decades of research and gives proof that laboratory fusion, based on fundamental physics principles, is possible. This Letter reports on the target, laser, design, and experimental advancements that led to this result.

Lawson Criterion for Ignition Exceeded in an Inertial Fusion Experiment

For more than half a century, researchers around the world have been engaged in attempts to achieve fusion ignition as a proof of principle of various fusion concepts. Following the Lawson criterion, an ignited plasma is one where the fusion heating power is high enough to overcome all the physical processes that cool the fusion plasma, creating a positive thermodynamic feedback loop with rapidly increasing temperature. In inertially confined fusion, ignition is a state where the fusion plasma can begin "burn propagation" into surrounding cold fuel, enabling the possibility of high energy gain. While "scientific breakeven" (i.e., unity target gain) has not yet been achieved (here target gain is 0.72, 1.37 MJ of fusion for 1.92 MJ of laser energy), this Letter reports the first controlled fusion experiment, using laser indirect drive, on the National Ignition Facility to produce capsule gain (here 5.8) and reach ignition by nine different formulations of the Lawson criterion.

Effect of Strongly Magnetized Electrons and Ions on Heat Flow and Symmetry of Inertial Fusion Implosions

This Letter presents the first observation on how a strong, 500 kG, externally applied B field increases the mode-two asymmetry in shock-heated inertial fusion implosions. Using a direct-drive implosion with polar illumination and imposed field, we observed that magnetization produces a significant increase in the implosion oblateness (a 2.5× larger P2 amplitude in x-ray self-emission images) compared with reference experiments with identical drive but with no field applied. The implosions produce strongly magnetized electrons (ω_{e}τ_{e}≫1) and ions (ω_{i}τ_{i}>1) that, as shown using simulations, restrict the cross field heat flow necessary for lateral distribution of the laser and shock heating from the implosion pole to the waist, causing the enhanced mode-two shape.

High-resolution x-ray radiography with Fresnel zone plates on the University of Rochester's OMEGA Laser Systems

Experiments performed at the Laboratory for Laser Energetics with a continuous-wave (cw) x-ray source and on the OMEGA and OMEGA EP Laser Systems [Boehly et al., Opt. Commun. 133, 495 (1997) and Waxer et al., Opt. Photonics News 16, 30 (2005)] have utilized a Fresnel zone plate (FZP) to obtain x-ray images with a spatial resolution as small as ∼1.5 μm. Such FZP images were obtained with a charge-coupled device or a framing camera at energies ranging from 4.5 keV to 6.7 keV using x-ray line emission from both the cw source and high-intensity, laser-beam-illuminated metal foils. In all cases, the resolution test results are determined from patterns and grids backlit by these sources. The resolutions obtained are shown to be due to a combination of the spectral content of the x-ray sources and detector resolution limited by the magnification of the images (14× to 22×). High-speed framing cameras were used to obtain FZP images with frame times as short as ∼30 ps. Double-shell implosions on OMEGA were backlit by laser-irradiated Fe foils, thus obtaining a framing-camera-limited, FZP-image resolution of ∼3 μm-4 μm.

Safety and Tolerability of SRX246, a Vasopressin 1a Antagonist, in Irritable Huntington's Disease Patients-A Randomized Phase 2 Clinical Trial

SRX246 is a vasopressin (AVP) 1a receptor antagonist that crosses the blood-brain barrier. It reduced impulsive aggression, fear, depression and anxiety in animal models, blocked the actions of intranasal AVP on aggression/fear circuits in an experimental medicine fMRI study and demonstrated excellent safety in Phase 1 multiple-ascending dose clinical trials. The present study was a 3-arm, multicenter, randomized, placebo-controlled, double-blind, 12-week, dose escalation study of SRX246 in early symptomatic Huntington's disease (HD) patients with irritability. Our goal was to determine whether SRX246 was safe and well tolerated in these HD patients given its potential use for the treatment of problematic neuropsychiatric symptoms. Participants were randomized to receive placebo or to escalate to 120 mg twice daily or 160 mg twice daily doses of SRX246. Assessments included standard safety tests, the Unified Huntington's Disease Rating Scale (UHDRS), and exploratory measures of problem behaviors. The groups had comparable demographics, features of HD and baseline irritability. Eighty-two out of 106 subjects randomized completed the trial on their assigned dose of drug. One-sided exact-method confidence interval tests were used to reject the null hypothesis of inferior tolerability or safety for each dose group vs. placebo. Apathy and suicidality were not affected by SRX246. Most adverse events in the active arms were considered unlikely to be related to SRX246. The compound was safe and well tolerated in HD patients and can be moved forward as a candidate to treat irritability and aggression.

The CLN3 Disease Staging System: A new tool for clinical research in Batten disease

OBJECTIVE

To develop a disease-specific staging system for CLN3 disease and to test the hypothesis that salient and discrete clinical features of CLN3 disease may be used to define disease stages by analyzed data from an 18-year-long natural history study.

METHODS

A proposed staging system, the CLN3 Staging System (CLN3SS), was based on salient and clinically meaningful endpoints. The relationships between stage and age, stage and Unified Batten Disease Rating Scale (UBDRS) physical severity score, and stage and UBDRS capability impairment subscale scores were determined. We used t tests to determine whether the stages were significantly different from each other on the basis of age and scores.

RESULTS

Data were analyzed from 322 evaluations in 108 individuals. There were significant differences among the stages based on age and severity scores. For individuals with longitudinal data, no individual reverted to a less severe stage over time.

CONCLUSION

The CLN3SS is a disease-specific staging system that can be used to classify individuals into specific strata based on age and disease severity. The CLN3SS has potential applications in clinical trials for cohort stratification.

Inferred UV fluence focal-spot profiles from soft x-ray pinhole-camera measurements on OMEGA

A method was developed with laser-irradiated Au planar foils to characterize the focal spot of UV laser beams on a target at full energy from soft x-ray emission. A pinhole camera with a back-thinned charge-coupled device detector and filtration with thin Be and Al foil filters provides images of the x-ray emission at photon energies <2 keV. This method requires a careful measurement of the relationship between the applied UV fluence and the x-ray signal, which can be described by a power-law dependence. The measured exponent γ ∼ 2 provides a dynamic range of ∼25 for the inferred UV fluence. UV fluence profiles of selected beams were measured for 100-ps and 1-ns laser pulses and were compared to directly measured profiles from an UV equivalent-target-plane diagnostic. The inferred spot size and super-Gaussian order from the x-ray technique agree within several percent with the values measured with the direct UV measurements.

A novel, hybrid, single- and multi-site clinical trial design for CLN3 disease, an ultra-rare lysosomal storage disorder

BACKGROUND

Travel burden often substantially limits the ability of individuals to participate in clinical trials. Wide geographic dispersion of individuals with rare diseases poses an additional key challenge in the conduct of clinical trials for rare diseases. Novel technologies and methods can improve access to research by connecting participants in their homes and local communities to a distant research site. For clinical trials, however, understanding of factors important for transition from traditional multi-center trial models to local participation models is limited. We sought to test a novel, hybrid, single- and multi-site clinical trial design in the context of a trial for Juvenile Neuronal Ceroid Lipofuscinosis (CLN3 disease), a very rare pediatric neurodegenerative disorder.

METHODS

We created a "hub and spoke" model for implementing a 22-week crossover clinical trial of mycophenolate compared with placebo, with two 8-week study arms. A single central site, the "hub," conducted screening, consent, drug dispensing, and tolerability and efficacy assessments. Each participant identified a clinician to serve as a collaborating "spoke" site to perform local safety monitoring. Study participants traveled to the hub at the beginning and end of each study arm, and to their individual spoke site in the intervening weeks.

RESULTS

A total of 18 spoke sites were established for 19 enrolled study participants. One potential participant was unable to identify a collaborating local site and was thus unable to participate. Study start-up required a median 6.7 months (interquartile range = 4.6-9.2 months). Only 33.3% (n = 6 of 18) of spoke site investigators had prior clinical trial experience, thus close collaboration with respect to study startup, training, and oversight was an important requirement. All but one participant completed all study visits; no study visits were missed due to travel requirements.

CONCLUSIONS

This study represents a step toward local trial participation for patients with rare diseases. Even in the context of close oversight, local participation models may be best suited for studies of compounds with well-understood side-effect profiles, for those with straightforward modes of administration, or for studies requiring extended follow-up periods.

Tripled yield in direct-drive laser fusion through statistical modelling

Focusing laser light onto a very small target can produce the conditions for laboratory-scale nuclear fusion of hydrogen isotopes. The lack of accurate predictive models, which are essential for the design of high-performance laser-fusion experiments, is a major obstacle to achieving thermonuclear ignition. Here we report a statistical approach that was used to design and quantitatively predict the results of implosions of solid deuterium-tritium targets carried out with the 30-kilojoule OMEGA laser system, leading to tripling of the fusion yield to its highest value so far for direct-drive laser fusion. When scaled to the laser energies of the National Ignition Facility (1.9 megajoules), these targets are predicted to produce a fusion energy output of about 500 kilojoules-several times larger than the fusion yields currently achieved at that facility. This approach could guide the exploration of the vast parameter space of thermonuclear ignition conditions and enhance our understanding of laser-fusion physics.

The single-line-of-sight, time-resolved x-ray imager diagnostic on OMEGA

The single-line-of-sight, time-resolved x-ray imager (SLOS-TRXI) on OMEGA is one of a new generation of fast-gated x-ray cameras comprising an electron pulse-dilation imager and a nanosecond-gated, burst-mode, hybrid complementary metal-oxide semiconductor sensor. SLOS-TRXI images the core of imploded cryogenic deuterium-tritium shells in inertial confinement fusion experiments in the ∼4- to 9-keV photon energy range with a pinhole imager onto a photocathode. The diagnostic is mounted on a fixed port almost perpendicular to a 16-channel, framing-camera-based, time-resolved Kirkpatrick-Baez microscope, providing a second time-gated line of sight for hot-spot imaging on OMEGA. SLOS-TRXI achieves ∼40-ps temporal resolution and better than 10-μm spatial resolution. Shots with neutron yields of up to 1 × 10¹⁴ were taken without observed neutron-induced background signal. The implosion images from SLOS-TRXI show the evolution of the stagnating core.

A framed, 16-image Kirkpatrick-Baez x-ray microscope

A 16-image Kirkpatrick-Baez (KB)-type x-ray microscope consisting of compact KB mirrors [F. J. Marshall, Rev. Sci. Instrum. 83, 10E518 (2012)] has been assembled for the first time with mirrors aligned to allow it to be coupled to a high-speed framing camera. The high-speed framing camera has four independently gated strips whose emission sampling interval is ∼30 ps. Images are arranged four to a strip with ∼60-ps temporal spacing between frames on a strip. By spacing the timing of the strips, a frame spacing of ∼15 ps is achieved. A framed resolution of ∼6-μm is achieved with this combination in a 400-μm region of laser-plasma x-ray emission in the 2- to 8-keV energy range. A principal use of the microscope is to measure the evolution of the implosion stagnation region of cryogenic DT target implosions on the University of Rochester's OMEGA Laser System [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)]. The unprecedented time and spatial resolutions achieved with this framed, multi-image KB microscope have made it possible to accurately determine the cryogenic implosion core emission size and shape at the peak of stagnation. These core size measurements, taken in combination with those of ion temperature, neutron-production temporal width, and neutron yield allow for inference of core pressures, currently exceeding 50 Gbar in OMEGA cryogenic target implosions [Regan et al., Phys. Rev. Lett. 117, 025001 (2016)].

Multivariate analyses of peripheral blood leukocyte transcripts distinguish Alzheimer's, Parkinson's, control, and those at risk for developing Alzheimer's

The need for a reliable, simple, and inexpensive blood test for Alzheimer's disease (AD) suitable for use in a primary care setting is widely recognized. This has led to a large number of publications describing blood tests for AD, which have, for the most part, not been replicable. We have chosen to examine transcripts expressed by the cellular, leukocyte compartment of blood. We have used hypothesis-based cDNA arrays and quantitative PCR to quantify the expression of selected sets of genes followed by multivariate analyses in multiple independent samples. Rather than a single study with no replicates, we chose an experimental design in which there were multiple replicates using different platforms and different sample populations. We have divided 177 blood samples and 27 brain samples into multiple replicates to demonstrate the ability to distinguish early clinical AD (Clinical Dementia Rating scale 0.5), Parkinson's disease (PD), and cognitively unimpaired APOE4 homozygotes, as well as to determine persons at risk for future cognitive impairment with significant accuracy. We assess our methods in a training/test set and also show that the variables we use distinguish AD, PD, and control brain. Importantly, we describe the variability of the weights assigned to individual transcripts in multivariate analyses in repeated studies and suggest that the variability we describe may be the cause of inability to repeat many earlier studies. Our data constitute a proof of principle that multivariate analysis of the transcriptome related to cell stress and inflammation of peripheral blood leukocytes has significant potential as a minimally invasive and inexpensive diagnostic tool for diagnosis and early detection of risk for AD.

Systematic Fuel Cavity Asymmetries in Directly Driven Inertial Confinement Fusion Implosions

We present narrow-band self-emission x-ray images from a titanium tracer layer placed at the fuel-shell interface in 60-laser-beam implosion experiments at the OMEGA facility. The images are acquired during deceleration with inferred convergences of ∼9-14. Novel here is that a systematically observed asymmetry of the emission is linked, using full sphere 3D implosion modeling, to performance-limiting low mode asymmetry of the drive.

Thalamic DBS with a constant-current device in essential tremor: A controlled clinical trial

INTRODUCTION

This study of thalamic deep brain stimulation (DBS) investigated whether a novel constant-current device improves tremor and activities of daily living (ADL) in patients with essential tremor (ET).

METHODS

A prospective, controlled, multicenter study was conducted at 12 academic centers. We investigated the safety and efficacy of unilateral and bilateral constant-current DBS of the ventralis intermedius (VIM) nucleus of the thalamus in patients with essential tremor whose tremor was inadequately controlled by medications. The primary outcome measure was a rater-blinded assessment of the change in the target limb tremor score in the stimulation-on versus stimulation-off state six months following surgery. Multiple secondary outcomes were assessed at one-year follow-up, including motor, mood, and quality-of-life measures.

RESULTS

127 patients were implanted with VIM DBS. The blinded, primary outcome variable (n = 76) revealed a mean improvement of 1.25 ± 1.26 points in the target limb tremor rating scale (TRS) score in the arm contralateral to DBS (p < 0.001). Secondary outcome variables at one year revealed significant improvements (p ≤ 0.001) in quality of life, depression symptoms, and ADL scores. Forty-seven patients had a second contralateral VIM-DBS, and this group demonstrated reduction in second-sided tremor at 180 days (p < 0.001). Serious adverse events related to the surgery included infection (n = 3), intracranial hemorrhage (n = 3), and device explantation (n = 3).

CONCLUSION

Unilateral and bilateral constant-current VIM DBS significantly improves upper extremity tremor, ADL, quality of life, and depression in patients with severe ET.

Publisher's Note: Demonstration of Fuel Hot-Spot Pressure in Excess of 50 Gbar for Direct-Drive, Layered Deuterium-Tritium Implosions on OMEGA [Phys. Rev. Lett. 117, 025001 (2016)]

This corrects the article DOI: 10.1103/PhysRevLett.117.025001.

Demonstration of Fuel Hot-Spot Pressure in Excess of 50 Gbar for Direct-Drive, Layered Deuterium-Tritium Implosions on OMEGA

A record fuel hot-spot pressure P_{hs}=56±7  Gbar was inferred from x-ray and nuclear diagnostics for direct-drive inertial confinement fusion cryogenic, layered deuterium-tritium implosions on the 60-beam, 30-kJ, 351-nm OMEGA Laser System. When hydrodynamically scaled to the energy of the National Ignition Facility, these implosions achieved a Lawson parameter ∼60% of the value required for ignition [A. Bose et al., Phys. Rev. E 93, 011201(R) (2016)], similar to indirect-drive implosions [R. Betti et al., Phys. Rev. Lett. 114, 255003 (2015)], and nearly half of the direct-drive ignition-threshold pressure. Relative to symmetric, one-dimensional simulations, the inferred hot-spot pressure is approximately 40% lower. Three-dimensional simulations suggest that low-mode distortion of the hot spot seeded by laser-drive nonuniformity and target-positioning error reduces target performance.

Core conditions for alpha heating attained in direct-drive inertial confinement fusion

It is shown that direct-drive implosions on the OMEGA laser have achieved core conditions that would lead to significant alpha heating at incident energies available on the National Ignition Facility (NIF) scale. The extrapolation of the experimental results from OMEGA to NIF energy assumes only that the implosion hydrodynamic efficiency is unchanged at higher energies. This approach is independent of the uncertainties in the physical mechanism that degrade implosions on OMEGA, and relies solely on a volumetric scaling of the experimentally observed core conditions. It is estimated that the current best-performing OMEGA implosion [Regan et al., Phys. Rev. Lett. 117, 025001 (2016)10.1103/PhysRevLett.117.025001] extrapolated to a 1.9 MJ laser driver with the same illumination configuration and laser-target coupling would produce 125 kJ of fusion energy with similar levels of alpha heating observed in current highest performing indirect-drive NIF implosions.

Natural history of multiple system atrophy in the USA: a prospective cohort study

Background

Multiple system atrophy (MSA) is a rare, fatal neurodegenerative disorder exhibiting a combination of parkinsonism and/or cerebellar ataxia with autonomic failure. We report the first North American prospective natural history study of MSA, and the effects of phenotype and autonomic failure on prognosis.

Methods

175 subjects with probable MSA, both MSA-P and MSA-C, were recruited and prospectively followed for 5 years with evaluations every 6 months in 12 centers. Natural history was evaluated by Kaplan-Meier survival analysis. We compared MSA-P with MSA-C and evaluated predictors of outcome. These subjects were evaluated with UMSARS I (a functional score of symptoms and ability to undertake activities of daily living), UMSARS II (neurological motor evaluation), and the Composite Autonomic Symptoms Scale (COMPASS)-select (a measure of autonomic symptoms and autonomic functional status.

Findings

Mean age of symptom onset was 63.4 (SD 8.57) years. Median survival from symptom onset by Kaplan-Meier analysis was 9.8 years (95% CI 8.8-10.7). Subjects with severe symptomatic autonomic failure (symptomatic orthostatic hypotension, urinary incontinence) at diagnosis had a worse prognosis, surviving 8.0 years (95% CI, 6.5-9.5, n=62) while remaining subjects survived a median of 10.3 years (95% CI, 9.3-11.4, n=113). At baseline MSA-P (n=126) and MSA-C (n=49) were not different in symptoms and function, UMSARS I, 25.2 (8.08) vs 24.6 (8.34), p=0.835; UMSARS II, 26.4 (8.77) vs 25.4 (10.51), p=0.7635; COMPASS_select), 43.5 (18.66) vs 42.8 (19.56), p=0.835. Progression, evaluated by change in UMSARS I, UMSARS II, COMPASS_select over the next 5 years, was not significantly different between MSA-P and MSA-C. Median time to death from enrollment baseline was 1.8 (95% CI, 0.9-2.7) years.

Interpretation

Probable MSA represents late-stage disease with short survival. Natural history of MSA-P and MSA-C are similar. Severe symptomatic autonomic failure at diagnosis is associated with worse prognosis.

Funding

National Institutes of Health (P01 NS044233), Mayo CTSA (UL1 TR000135), the Kathy Shih Memorial Foundation, and Mayo funds.

Gigabar spherical shock generation on the OMEGA laser

This Letter presents the first experimental demonstration of the capability to launch shocks of several-hundred Mbar in spherical targets--a milestone for shock ignition [R. Betti et al., Phys. Rev. Lett. 98, 155001 (2007)]. Using the temporal delay between the launching of the strong shock at the outer surface of the spherical target and the time when the shock converges at the center, the shock-launching pressure can be inferred using radiation-hydrodynamic simulations. Peak ablation pressures exceeding 300 Mbar are inferred at absorbed laser intensities of ∼3×10(15)  W/cm2. The shock strength is shown to be significantly enhanced by the coupling of suprathermal electrons with a total converted energy of up to 8% of the incident laser energy. At the end of the laser pulse, the shock pressure is estimated to exceed ∼1  Gbar because of convergence effects.

The NIF x-ray spectrometer calibration campaign at Omega

The calibration campaign of the National Ignition Facility X-ray Spectrometer (NXS) was carried out at the Omega laser facility. Spherically symmetric, laser-driven, millimeter-scale x-ray sources of K-shell and L-shell emission from various mid-Z elements were designed for the 2-18 keV energy range of the NXS. The absolute spectral brightness was measured by two calibrated spectrometers. We compare the measured performance of the target design to radiation hydrodynamics simulations.

Masked-backlighter technique used to simultaneously image x-ray absorption and x-ray emission from an inertial confinement fusion plasma

A method to simultaneously image both the absorption and the self-emission of an imploding inertial confinement fusion plasma has been demonstrated on the OMEGA Laser System. The technique involves the use of a high-Z backlighter, half of which is covered with a low-Z material, and a high-speed x-ray framing camera aligned to capture images backlit by this masked backlighter. Two strips of the four-strip framing camera record images backlit by the high-Z portion of the backlighter, while the other two strips record images aligned with the low-Z portion of the backlighter. The emission from the low-Z material is effectively eliminated by a high-Z filter positioned in front of the framing camera, limiting the detected backlighter emission to that of the principal emission line of the high-Z material. As a result, half of the images are of self-emission from the plasma and the other half are of self-emission plus the backlighter. The advantage of this technique is that the self-emission simultaneous with backlighter absorption is independently measured from a nearby direction. The absorption occurs only in the high-Z backlit frames and is either spatially separated from the emission or the self-emission is suppressed by filtering, or by using a backlighter much brighter than the self-emission, or by subtraction. The masked-backlighter technique has been used on the OMEGA Laser System to simultaneously measure the emission profiles and the absorption profiles of polar-driven implosions.

Soft x-ray backlighting of cryogenic implosions using a narrowband crystal imaging system (invited)

A high-performance cryogenic DT inertial confinement fusion implosion experiment is an especially challenging backlighting configuration because of the high self-emission of the core at stagnation and the low opacity of the DT shell. High-energy petawatt lasers such as OMEGA EP promise significantly improved backlighting capabilities by generating high x-ray intensities and short emission times. A narrowband x-ray imager with an astigmatism-corrected bent quartz crystal for the Si Heα line at ∼1.86 keV was developed to record backlit images of cryogenic direct-drive implosions. A time-gated recording system minimized the self-emission of the imploding target. A fast target-insertion system capable of moving the backlighter target ∼7 cm in ∼100 ms was developed to avoid interference with the cryogenic shroud system. With backlighter laser energies of ∼1.25 kJ at a 10-ps pulse duration, the radiographic images show a high signal-to-background ratio of >100:1 and a spatial resolution of the order of 10 μm. The backlit images can be used to assess the symmetry of the implosions close to stagnation and the mix of ablator material into the dense shell.

Exploration of the transition from the hydrodynamiclike to the strongly kinetic regime in shock-driven implosions

Clear evidence of the transition from hydrodynamiclike to strongly kinetic shock-driven implosions is, for the first time, revealed and quantitatively assessed. Implosions with a range of initial equimolar D3He gas densities show that as the density is decreased, hydrodynamic simulations strongly diverge from and increasingly overpredict the observed nuclear yields, from a factor of ∼2 at 3.1  mg/cm3 to a factor of 100 at 0.14  mg/cm3. (The corresponding Knudsen number, the ratio of ion mean-free path to minimum shell radius, varied from 0.3 to 9; similarly, the ratio of fusion burn duration to ion diffusion time, another figure of merit of kinetic effects, varied from 0.3 to 14.) This result is shown to be unrelated to the effects of hydrodynamic mix. As a first step to garner insight into this transition, a reduced ion kinetic (RIK) model that includes gradient-diffusion and loss-term approximations to several transport processes was implemented within the framework of a one-dimensional radiation-transport code. After empirical calibration, the RIK simulations reproduce the observed yield trends, largely as a result of ion diffusion and the depletion of the reacting tail ions.

Experience, knowledge, and opinions about childhood genetic testing in Batten disease

BACKGROUND AND OBJECTIVES

Policies for genetic testing in children (GTIC) focus on medical or psychosocial benefit to the child, discouraging or prohibiting carrier testing, and advising caution regarding pre-symptomatic diagnosis if no treatment exists. This study sought to understand parents' perspectives on these issues and determine their experiences and knowledge related to genetic testing for Batten disease - a set of inherited neurodegenerative diseases of childhood onset for which no disease modifying therapies yet exist.

METHODS

Parents of children with Batten disease completed a survey of their knowledge of genetics, experience with genetic testing, and opinions regarding GTIC.

RESULTS

54% had sought genetic testing for non-affected family members, including predictive diagnosis of healthy, at-risk children. Participation in any genetic counseling was associated with greater knowledge on questions about genetics. The majority of parents felt it was better to know ahead of time that a child would develop Batten disease, believed that this knowledge would not alter how they related to their child, and that parents should have the final say in deciding whether to obtain GTIC.

CONCLUSIONS

Parents of children with an inherited disease are knowledgeable about genetics and wish to establish predictive or carrier status of at-risk children.

Classification and natural history of the neuronal ceroid lipofuscinoses

The neuronal ceroid lipofuscinoses represent a group of disorders characterized by neurodegeneration and intracellular accumulation of an auto-fluorescent lipopigment (ceroid lipofuscin). Together, they represent the most prevalent class of childhood neurodegenerative disease. The neuronal ceroid lipofuscinoses encompass several distinct biological entities that vary in age of onset, specific neurologic phenotype, and rate of progression. In this review, we describe 9 major forms and present a classification scheme. Understanding the age of onset, clinical features, and natural history can inform rational diagnostics. Better knowledge of the natural histories of these disorders is necessary to shed light on the underlying pathobiology and to develop new therapeutics.

Methodology of clinical research in rare diseases: development of a research program in juvenile neuronal ceroid lipofuscinosis (JNCL) via creation of a patient registry and collaboration with patient advocates

INTRODUCTION

Juvenile neuronal ceroid lipofuscinosis (JNCL; Batten disease) is a rare, inherited, fatal lysosomal storage childhood disorder. True for many rare diseases, there are no treatments that impact the course of JNCL. The University of Rochester Batten Center's (URBC) mission is to find treatments to slow, halt, or prevent JNCL.

OBJECTIVES

Our initial objective was to develop clinical research infrastructure preparatory to clinical trials, establish a JNCL research cohort, construct a disease-specific clinical outcome measure, and validate a non-invasive diagnostic sampling method. The long-term objective is to design and implement JNCL clinical trials.

METHODS

The Unified Batten Disease Rating Scale (UBDRS) was developed. The Batten Disease Support and Research Association (BDSRA) referred participants; annual BDSRA meetings provided a mobile research setting for registry enrollment and UBDRS piloting. Neuropsychological examinations were performed, enabling external validation of the UBDRS. Buccal epithelial cell collection for genotyping was introduced. Telemedicine for remote UBDRS assessment was piloted.

RESULTS

The registry enrolled 198 families representing 237 children with NCL. The UBDRS was piloted, was validated and has been used to collect natural history data from 120 subjects. Funding and regulatory approval were obtained for a recently launched phase II clinical trial. Several additional lines of inquiry were reported.

CONCLUSION

The registry and BDSRA collaboration have enabled development of a clinical rating scale, natural history and neuropsychological studies, and genetic studies for disease confirmation. This work highlights an approach for preparatory natural history research and infrastructure development needed to facilitate efficient implementation of clinical trials in rare diseases.

Laser-beam zooming to mitigate crossed-beam energy losses in direct-drive implosions

Spherically symmetric direct-drive-ignition designs driven by laser beams with a focal-spot size nearly equal to the target diameter suffer from energy losses due to crossed-beam energy transfer (CBET). Significant reduction of CBET and improvements in implosion hydrodynamic efficiency can be achieved by reducing the beam diameter. Narrow beams increase low-mode perturbations of the targets because of decreased illumination uniformity that degrades implosion performance. Initiating an implosion with nominal beams (equal in size to the target diameter) and reducing the beam diameter by ∼ 30%-40% after developing a sufficiently thick target corona, which smooths the perturbations, mitigate CBET while maintaining low-mode target uniformity in ignition designs with a fusion gain ≫ 1.

Compact Kirkpatrick-Baez microscope mirrors for imaging laser-plasma x-ray emission

Compact Kirkpatrick-Baez microscope mirror components for use in imaging laser-plasma x-ray emission have been manufactured, coated, and tested. A single mirror pair has dimensions of 14 × 7 × 9 mm and a best resolution of ~5 μm. The mirrors are coated with Ir providing a useful energy range of 2-8 keV when operated at a grazing angle of 0.7°. The mirrors can be circularly arranged to provide 16 images of the target emission a configuration best suited for use in combination with a custom framing camera [F. J. Marshall, J. A. Oertel, and P. J. Walsh, Rev. Sci. Instrum. 75, 4045 (2004)]. An alternative arrangement of the mirrors would allow alignment of the images with a four-strip framing camera such as described in D. K. Bradley et al. [Rev. Sci. Instrum. 66, 716 (1995)].

A new compact, high sensitivity neutron imaging system

We have developed a new small neutron imaging system (SNIS) diagnostic for the OMEGA laser facility. The SNIS uses a penumbral coded aperture and has been designed to record images from low yield (10(9)-10(10) neutrons) implosions such as those using deuterium as the fuel. This camera was tested at OMEGA in 2009 on a rugby hohlraum energetics experiment where it recorded an image at a yield of 1.4 × 10(10). The resolution of this image was 54 μm and the camera was located only 4 meters from target chamber centre. We recently improved the instrument by adding a cooled CCD camera. The sensitivity of the new camera has been fully characterized using a linear accelerator and a (60)Co γ-ray source. The calibration showed that the signal-to-noise ratio could be improved by using raw binning detection.

Note: spatial resolution of Fuji BAS-TR and BAS-SR imaging plates

The spatial resolution of two types of imaging plates, Fuji BAS-TR and Fuji BAS-SR, has been measured using a knife-edge x-ray source of 8-keV Cu K(α) radiation. The values for the spatial resolution, defined as the distance between 10% and 90% levels of the edge spread function, are 94 μm and 109 μm, respectively. The resolution values are important for quantitative analysis of x-ray and particle imaging and spectroscopic diagnostics.

Approach to the elderly patient with gait disturbance

The prevalence of gait disturbances and falls increases dramatically with age, but these problems are not universal in the elderly. They should trigger a systematic search for underlying disease states, many of which can be treated medically or surgically, or significantly ameliorated through provision of physical therapy focused on gait training and aids to ambulation, removal of safety hazards in the environment, and the elimination of polypharmacy. While cardiovascular, orthopedic, and rheumatologic diseases account for the majority of gait disturbances in the elderly, the aim here is to outline an approach to the diagnosis and treatment of a broad array of neurologic conditions causing gait disturbance in the elderly.

Females experience a more severe disease course in Batten disease

Juvenile neuronal ceroid lipofuscinosis (JNCL; CLN3 disease; Batten disease) is an autosomal recessive neurodegenerative disease of childhood. Symptoms typically present at school age with vision loss followed by progressive cognitive decline, motor dysfunction, seizures, and behavior problems. Studies on sex differences in JNCL have yielded mixed results, but parent anecdotes suggest that females experience a more precipitous disease course. Therefore, we sought to determine if sex-based differences exist in JNCL. We used data from the Unified Batten Disease Rating Scale (UBDRS), the Batten Disease Support and Research Association (BDSRA) database, and the PedsQL quality of life (QoL) survey to evaluate sex-based differences in functional independence and time from symptom onset to death. On average, females had JNCL symptom onset one year later and death one year earlier than did males. Despite a later age at onset, females had lower functional capability, earlier loss of independent function, and lower physical QoL. Future research in sex differences in JNCL may help to further understand the biological mechanisms underpinning the disease course and may point to targeted therapies.

Increasing hydrodynamic efficiency by reducing cross-beam energy transfer in direct-drive-implosion experiments

A series of experiments to determine the optimum laser-beam radius by balancing the reduction of cross-beam energy transfer (CBET) with increased illumination nonuniformities shows that the hydrodynamic efficiency is increased by ∼35%, which leads to a factor of 2.6 increase in the neutron yield when the laser-spot size is reduced by 20%. Over this range, the absorption is measured to increase by 15%, resulting in a 17% increase in the implosion velocity and a 10% earlier bang time. When reducing the ratio of laser-spot size to a target radius below 0.8, the rms amplitudes of the nonuniformities imposed by the smaller laser spots are measured at a convergence ratio of 2.5 to exceed 8  μm and the neutron yield saturates despite increasing absorbed energy, implosion velocity, and decreasing bang time. The results agree well with hydrodynamic simulations that include both nonlocal and CBET models.

Development of the large neutron imaging system for inertial confinement fusion experiments

Inertial confinement fusion (ICF) requires a high resolution (~10 μm) neutron imaging system to observe deuterium and tritium (DT) core implosion asymmetries. A new large (150 mm entrance diameter: scaled for Laser MégaJoule [P. A. Holstein, F. Chaland, C. Charpin, J. M. Dufour, H. Dumont, J. Giorla, L. Hallo, S. Laffite, G. Malinie, Y. Saillard, G. Schurtz, M. Vandenboomgaerde, and F. Wagon, Laser and Particle Beams 17, 403 (1999)]) neutron imaging detector has been developed for such ICF experiments. The detector has been fully characterized using a linear accelerator and a (60)Co γ-ray source. A penumbral aperture was used to observe DT-gas-filled target implosions performed on the OMEGA laser facility. [T. R. Boehly, D. L. Brown, R. S. Craxton, R. L. Keck, J. P. Knauer, J. H. Kelly, T. J. Kessler, S. A. Kumpan, S. J. Loucks, S. A. Letzring, F. J. Marshall, R. L. McCrory, S. F. B. Morse, W. Seka, J. M. Soures, and C. P. Verdon, Opt. Commun. 133, 495 (1997)] Neutron core images of 14 MeV with a resolution of 15 μm were obtained and are compared to x-ray images of comparable resolution.

Quantifying physical decline in juvenile neuronal ceroid lipofuscinosis (Batten disease)

OBJECTIVE

To use the Unified Batten Disease Rating Scale (UBDRS) to measure the rate of decline in physical and functional capability domains in patients with juvenile neuronal ceroid lipofuscinosis (JNCL) or Batten disease, a neurodegenerative lysosomal storage disorder. We have evaluated the UBDRS in subjects with JNCL since 2002; during that time, the scale has been refined to improve reliability and validity. Now that therapies are being proposed to prevent, slow, or reverse the course of JNCL, the UBDRS will play an important role in quantitatively assessing clinical outcomes in research trials.

METHODS

We administered the UBDRS to 82 subjects with JNCL genetically confirmed by CLN3 mutational analysis. Forty-four subjects were seen for more than one annual visit. From these data, the rate of physical impairment over time was quantified using multivariate linear regression and repeated-measures analysis.

RESULTS

The UBDRS Physical Impairment subscale shows worsening over time that proceeds at a quantifiable linear rate in the years following initial onset of clinical symptoms. This deterioration correlates with functional capability and is not influenced by CLN3 genotype.

CONCLUSION

The UBDRS is a reliable and valid instrument that measures clinical progression in JNCL. Our data support the use of the UBDRS to quantify the rate of progression of physical impairment in subjects with JNCL in clinical trials.

Quantitative telemedicine ratings in Batten disease: implications for rare disease research

OBJECTIVE

To determine if remote administration of the Unified Batten Disease Rating Scale (UBDRS) Physical Impairment subscale by telemedicine is reliable and feasible across a broad range of disease severity.

METHODS

For the majority (n = 10) of subjects, the examination was performed by a nonphysician who had been trained to perform the examination but not to score the subjects. A trained rater scored the subjects via live video; a second trained rater performed a separate examination in person and scored that examination. For 3 telemedicine evaluations, examinations were performed and scored by a trained rater while a second trained rater simultaneously scored the subjects via live video. Reliability was determined by intraclass correlation coefficient (ICC).

RESULTS

Subjects (n = 13) represented a wide range of disease severity. Remote administration of the UBDRS Physical Impairment subscale had high interrater reliability across all subjects (ICC = 0.94). When only the subjects (n = 10) who had been examined by the nonphysician and scored remotely were included in the analysis, the reliability was unchanged (ICC = 0.95).

CONCLUSIONS

The UBDRS Physical Impairment subscale is reliable and feasible for remote administration. Telemedicine has the potential to be a useful tool in rare neurologic disease research and clinical assessment.

Parent-reported benefits of flupirtine in juvenile neuronal ceroid lipofuscinosis (Batten disease; CLN3) are not supported by quantitative data

Juvenile neuronal ceroid lipofuscinosis (JNCL; CLN3 disease; Batten disease) is an autosomal recessive neurodegenerative disease of childhood that typically presents at school age with vision loss followed by progressive cognitive decline, motor dysfunction, seizures, and behavior problems. No therapy has been shown to slow the progression of disease in JNCL patients, and all current treatments are symptomatic. Flupirtine has been shown in vitro to reduce apoptosis in CLN3 lymphocytes. Based on that preclinical study, several children with JNCL were given flupirtine by their parents. The purpose of this study was to determine if there was evidence of attenuated disease progression in any JNCL symptom domain. We administered a survey to parents of JNCL children to qualitatively assess flupirtine efficacy. We used the Unified Batten Disease Rating Scale (UBDRS) to determine specific aspects of disease progression and investigated three age-related factors: loss of independent ambulation, loss of intelligible speech, and loss of ability to perform independent activities of daily living. The median scores for the UBDRS physical, behavior, and capability subscales were determined in flupirtine-exposed subjects and compared to age-, sex-, and genotype-matched subjects who had never taken flupirtine. Twenty-one percent of survey responders reported administering flupirtine to their JNCL child, and 56% of these families perceived beneficial changes that they attributed to flupirtine. However, our quantitative, prospectively obtained data did not show any change in JNCL disease progression that could be attributed to flupirtine. This study highlights the need for prospective experimental therapeutic research.

Fusion yield enhancement in magnetized laser-driven implosions

Enhancement of the ion temperature and fusion yield has been observed in magnetized laser-driven inertial confinement fusion implosions on the OMEGA Laser Facility. A spherical CH target with a 10 atm D2 gas fill was imploded in a polar-drive configuration. A magnetic field of 80 kG was embedded in the target and was subsequently trapped and compressed by the imploding conductive plasma. As a result of the hot-spot magnetization, the electron radial heat losses were suppressed and the observed ion temperature and neutron yield were enhanced by 15% and 30%, respectively.

Group patient visits for Parkinson disease: a randomized feasibility trial

BACKGROUND

Group patient visits are medical appointments shared among patients with a common medical condition. This care delivery method has demonstrated benefits for individuals with chronic conditions but has not been evaluated for Parkinson disease (PD).

METHODS

We conducted a 12-month, randomized trial of group patient visits vs usual (one-on-one) care for patients with PD. Visits were led by one of 3 study physicians, included patients and caregivers, and lasted approximately 90 minutes. Those receiving group visits had 4 sessions over 12 months. The primary outcome measure was feasibility as measured by the ability to recruit participants and by the proportion of participants who completed the study. The primary efficacy outcome was quality of life as measured by the PD Questionnaire-39.

RESULTS

Thirty patients and 27 caregivers enrolled in the study. Thirteen of the 15 patients randomized to group patient visits and 14 of the 15 randomized to usual care completed the study. Quality of life measured 12 months after baseline between the 2 groups was not different (25.9 points for group patient visits vs 26.0 points for usual care; p = 0.99).

CONCLUSIONS

Group patient visits may be a feasible means of providing care to individuals with PD and may offer an alternative or complementary method of care delivery for some patients and physicians.

CLASSIFICATION OF EVIDENCE

This study provides Class II evidence that group patient visits did not improve quality of life for individuals with PD over a 1-year period.

A U.S. survey of patients with Parkinson's disease: satisfaction with medical care and support groups

Relatively little is known about patient satisfaction with Parkinson's disease (PD) care and the use of support groups in the United States. We surveyed members of the Muhammad Ali Parkinson's Disease Registry to assess satisfaction with medical care and to evaluate support group use. Satisfaction was measured on a 5-point Likert scale, with high satisfaction defined as a four or five. We used multiple logistic regression to identify factors associated with high satisfaction and support group use. The response rate was 38% (726 of 1923). Most (57%) expressed high satisfaction with PD care. Individuals were most satisfied with the time their provider spent with them (61%) and PD education (56%) but least satisfied with prognostic information (35%) and information about non-drug interventions (28%). Patients seeing a PD specialist were three times more satisfied with their care than those seeing a general neurologist (OR = 3.00, 95% CI: 1.92-4.71; P < 0.0001). Support group use is common, and 61% of survey respondents had attended one at any point. Caucasian race (OR = 2.85, 95% CI: 1.45-5.61), PD duration (OR = 1.05 per year, CI: 1.01-1.10), and PD specialist care (OR = 1.80, CI: 1.16-2.77) were associated with greater support group attendance. Overall, 49% reported high satisfaction with their support group. The greatest concerns were specific needs not being addressed (15%) and insufficient expertise within the group (14%). Most individuals with Parkinson's disease expressed high levels of satisfaction, especially with specialist care. Specialty care and improved education, in the clinic or through support groups, may enhance satisfaction and health care quality.

Charge-injection-device performance in the high-energy-neutron environment of laser-fusion experiments

Charge-injection devices (CIDs) are being used to image x rays in laser-fusion experiments on the University of Rochester's OMEGA Laser System. The CID cameras are routinely used up to the maximum neutron yields generated (∼10(14) DT). The detectors are deployed in x-ray pinhole cameras and Kirkpatrick-Baez microscopes. The neutron fluences ranged from ∼10(7) to ∼10(9) neutrons/cm(2) and useful x-ray images were obtained even at the highest fluences. It is intended to use CID cameras at the National Ignition Facility (NIF) as a supporting means of recording x-ray images. The results of this work predict that x-ray images should be obtainable on the NIF at yields up to ∼10(15), depending on distance and shielding.

Demonstration of the highest deuterium-tritium areal density using multiple-picket cryogenic designs on OMEGA

The performance of triple-picket deuterium-tritium cryogenic target designs on the OMEGA Laser System [T. R. Boehly, Opt. Commun. 133, 495 (1997)] is reported. These designs facilitate control of shock heating in low-adiabat inertial confinement fusion targets. Areal densities up to 300 mg/cm2 (the highest ever measured in cryogenic deuterium-tritium implosions) are inferred in the experiments with an implosion velocity approximately 3x10(7) cm/s driven at peak laser intensities of 8x10(14) W/cm2. Extension of these designs to ignition on the National Ignition Facility [J. A. Paisner, Laser Focus World 30, 75 (1994)] is presented.

Plasma-density determination from x-ray radiography of laser-driven spherical implosions

The fuel layer density of an imploding laser-driven spherical shell is inferred from framed x-ray radiographs. The density distribution is determined by using Abel inversion to compute the radial distribution of the opacity kappa from the observed optical depth tau. With the additional assumption of the mass of the remaining fuel, the absolute density distribution is determined. This is demonstrated on the OMEGA laser system with two x-ray backlighters of different mean energies that lead to the same inferred density distribution independent of backlighter energy.

Diagnostics hardening for harsh environment in Laser Megajoule (invited)

The diagnostic designs for the Laser Megajoule (LMJ) will require components to operate in environments far more severe than those encountered in present facilities. This harsh environment will be induced by fluxes of neutrons, gamma rays, energetic ions, electromagnetic radiations, and, in some cases, debris and shrapnel, at levels several orders of magnitude higher than those experienced today on existing facilities. The lessons learned about the vulnerabilities of present diagnostic parts fielded mainly on OMEGA for many years, have been very useful guide for the design of future LMJ diagnostics. The present and future LMJ diagnostic designs including this vulnerability approach and their main mitigation techniques will be presented together with the main characteristics of the LMJ facility that provide for diagnostic protection.

A versatile high-resolution x-ray imager (HRXI) for laser-plasma experiments on OMEGA

A high-resolution x-ray imager (HRXI) devoted to laser-plasma experiments combines two state-of-the-art technologies developed in France: a high-resolution x-ray microscope and a high-speed x-ray streak camera. The resulting streaked imager achieves spatial and temporal resolutions of approximately 5 microm and approximately 10 ps, respectively. The HXRI has recorded enhanced spatial and temporal resolution radiographs of indirectly driven targets on OMEGA. This paper describes the main features of the instrument and details the activation process on OMEGA (particularly the alignment). Recent results obtained on joint CEA/LLE radiographic OMEGA experiments will also be presented.

High-areal-density fuel assembly in direct-drive cryogenic implosions

The first observation of ignition-relevant areal-density deuterium from implosions of capsules with cryogenic fuel layers at ignition-relevant adiabats is reported. The experiments were performed on the 60-beam, 30-kJUV OMEGA Laser System [T. R. Boehly, Opt. Commun. 133, 495 (1997)10.1016/S0030-4018(96)00325-2]. Neutron-averaged areal densities of 202+/-7 mg/cm2 and 182+/-7 mg/cm2 (corresponding to estimated peak fuel densities in excess of 100 g/cm3) were inferred using an 18-kJ direct-drive pulse designed to put the converging fuel on an adiabat of 2.5. These areal densities are in good agreement with the predictions of hydrodynamic simulations indicating that the fuel adiabat can be accurately controlled under ignition-relevant conditions.

Proton radiography of inertial fusion implosions

A distinctive way of quantitatively imaging inertial fusion implosions has resulted in the characterization of two different types of electromagnetic configurations and in the measurement of the temporal evolution of capsule size and areal density. Radiography with a pulsed, monoenergetic, isotropic proton source reveals field structures through deflection of proton trajectories, and areal densities are quantified through the energy lost by protons while traversing the plasma. The two field structures consist of (i) many radial filaments with complex striations and bifurcations, permeating the entire field of view, of magnetic field magnitude 60 tesla and (ii) a coherent, centrally directed electric field of order 10(9) volts per meter, seen in proximity to the capsule surface. Although the mechanism for generating these fields is unclear, their effect on implosion dynamics is potentially consequential.

Potential outcome measures and trial design issues for multiple system atrophy

Multiple system atrophy (MSA) is a neurodegenerative disorder exhibiting a combination of parkinsonism, cerebellar ataxia, and autonomic failure. A disease-specific scale, the Unified Multiple System Atrophy Rating Scale (UMSARS), has been developed and validated to measure progression of MSA, but its use as an outcome measure for therapeutic trials has not been evaluated. On the basis of twelve months of follow-up from an observational study of 67 patients with probable MSA, we evaluated three disease-specific scores: Activities of Daily Living, Motor Examination, and a combined score from the UMSARS and two general health scores, the Physical Health and Mental Health scores of the SF-36 health survey, for their use as outcome measures in a therapeutic trial. We discuss related design issues and provide sample size estimates. Scores based on the disease-specific UMSARS seemed to be equal or superior to scores based on the SF-36 health survey. They appeared to capture disease progression, were well correlated and required the smallest sample size. The UMSARS Motor Examination score exhibited the most favorable characteristics as an outcome measure for a therapeutic trial in MSA with 1 year of follow-up.

Spectroscopic determination of temperature and density spatial profiles and mix in indirect-drive implosion cores

In the field of inertial confinement fusion (ICF), work has been consistently progressing in the past decade toward a more fundamental understanding of the plasma conditions in ICF implosion cores. The research presented here represents a substantial evolution in the ability to diagnose plasma temperatures and densities, along with characteristics of mixing between fuel and shell materials. Mixing is a vital property to study and quantify, since it can significantly affect implosion quality. We employ a number of new spectroscopic techniques that allow us to probe these important quantities. The first technique developed is an emissivity analysis, which uses the emissivity ratio of the optically thin Lybeta and Hebeta lines to spectroscopically extract temperature profiles, followed by the solution of emissivity equations to infer density profiles. The second technique, an intensity analysis, models the radiation transport through the implosion core. The nature of the intensity analysis allows us to use an optically thick line, the Lyalpha, to extract information on mixing near the core edge. With this work, it is now possible to extract directly from experimental data not only detailed temperature and density maps of the core, but also spatial mixing profiles.

G2019S mutation in the leucine-rich repeat kinase 2 gene is not associated with multiple system atrophy

Multiple system atrophy (MSA) is characterized clinically by Parkinsonism, cerebellar dysfunction, and autonomic impairment. Multiple mutations in the LRRK2 gene are associated with parkinsonian disorders, and the most common one, the G2019S mutation, has been found in approximately 1% of sporadic cases of Parkinsonism. In a well-characterized cohort of 136 subjects with probable MSA and 110 neurologically evaluated control subjects, none carried the G2019S mutation. We conclude that the G2019S mutation in the LRRK2 gene is unlikely to be associated with MSA.