Burning plasma achieved in inertial fusion.

Obtaining a burning plasma is a critical step towards self-sustaining fusion energy1. A burning plasma is one in which the fusion reactions themselves are the primary source of heating in the plasma, which is necessary to sustain and propagate the burn, enabling high energy gain. After decades of fusion research, here we achieve a burning-plasma state in the laboratory. These experiments were conducted at the US National Ignition Facility, a laser facility delivering up to 1.9 megajoules of energy in pulses with peak powers up to 500 terawatts. We use the lasers to generate X-rays in a radiation cavity to indirectly drive a fuel-containing capsule via the X-ray ablation pressure, which results in the implosion process compressing and heating the fuel via mechanical work. The burning-plasma state was created using a strategy to increase the spatial scale of the capsule2,3 through two different implosion concepts4-7. These experiments show fusion self-heating in excess of the mechanical work injected into the implosions, satisfying several burning-plasma metrics3,8. Additionally, we describe a subset of experiments that appear to have crossed the static self-heating boundary, where fusion heating surpasses the energy losses from radiation and conduction. These results provide an opportunity to study α-particle-dominated plasmas and burning-plasma physics in the laboratory.

Cost-effectiveness of immediate total-body CT in patients with severe trauma (REACT-2 trial).

BACKGROUND: The effect of immediate total-body CT (iTBCT) on health economic aspects in patients with severe trauma is an underreported issue. This study determined the cost-effectiveness of iTBCT compared with conventional radiological imaging with selective CT (standard work-up (STWU)) during the initial trauma evaluation. METHODS: In this multicentre RCT, adult patients with a high suspicion of severe injury were randomized in-hospital to iTBCT or STWU. Hospital healthcare costs were determined for the first 6 months after the injury. The probability of iTBCT being cost-effective was calculated for various levels of willingness-to-pay per extra patient alive. RESULTS: A total of 928 Dutch patients with complete clinical follow-up were included. Mean costs of hospital care were €25 809 (95 per cent bias-corrected and accelerated (bca) c.i. €22 617 to €29 137) for the iTBCT group and €26 155 (€23 050 to €29 344) for the STWU group, a difference per patient in favour of iTBCT of €346 (€4987 to €4328) (P = 0.876). Proportions of patients alive at 6 months were not different. The proportion of patients alive without serious morbidity was 61.6 per cent in the iTBCT group versus 66.7 per cent in the STWU group (difference -5.1 per cent; P = 0.104). The probability of iTBCT being cost-effective in keeping patients alive remained below 0.56 for the whole group, but was higher in patients with multiple trauma (0.8-0.9) and in those with traumatic brain injury (more than 0.9). CONCLUSION: Economically, from a hospital healthcare provider perspective, iTBCT should be the diagnostic strategy of first choice in patients with multiple trauma or traumatic brain injury.

Record Energetics for an Inertial Fusion Implosion at NIF.

Inertial confinement fusion seeks to create burning plasma conditions in a spherical capsule implosion, which requires efficiently absorbing the driver energy in the capsule, transferring that energy into kinetic energy of the imploding DT fuel and then into internal energy of the fuel at stagnation. We report new implosions conducted on the National Ignition Facility (NIF) with several improvements on recent work [Phys. Rev. Lett. 120, 245003 (2018)PRLTAO0031-900710.1103/PhysRevLett.120.245003; Phys. Rev. E 102, 023210 (2020)PRESCM2470-004510.1103/PhysRevE.102.023210]: larger capsules, thicker fuel layers to mitigate fuel-ablator mix, and new symmetry control via cross-beam energy transfer; at modest velocities, these experiments achieve record values for the implosion energetics figures of merit as well as fusion yield for a NIF experiment.

Enhancing the communication of functional neurological disorder diagnosis: a multidisciplinary education session.

BACKGROUND AND PURPOSE: Functional neurological disorder (FND) is a common diagnosis within neurology. Effective communication of the diagnosis is known to be an important part of treatment and can result in reduction or cessation of symptoms, as well as decreased healthcare utilisation. A single group education session, facilitated by professionals commonly involved in the care of patients with FND, was developed to further enhance patients' and relatives' understanding and acceptance of diagnosis. METHODS: Patients and relatives attending a single education session were asked to complete self-report ratings of understanding of diagnosis, acceptance of diagnosis, belief in treatability and hopefulness regarding recovery, at the beginning and end of the session. Satisfaction data were also collected. RESULTS: Data were obtained from 193 patients and 153 relatives. Patients had experienced a median duration of symptoms of 4 years, and more than 80% of patients reported more than one functional neurological symptom. There were significant increases in terms of understanding, acceptance, belief in treatability and hopefulness for patients and relatives. Effect sizes ranged from large for improved understanding of FND to small-to-medium for increased agreement with FND diagnosis. High levels of satisfaction were also reported. CONCLUSIONS: A multidisciplinary, single group education session is an effective and acceptable method of increasing understanding and acceptance of an FND diagnosis, even for patients with a long duration of symptoms and high symptom burden. It could help improve readiness for further treatment.

Hypomimia in Parkinson's disease: an axial sign responsive to levodopa.

BACKGROUND AND PURPOSE: Hypomimia is a prominent clinical feature in people with Parkinson's disease (PD), but it remains under-investigated. We aimed to examine the clinical correlates of hypomimia in PD and to determine whether this is a levodopa-responsive sign. METHODS: We included 89 people with PD. Hypomimia was assessed from digital video recordings by movement disorder specialists. Clinical evaluation included use of the Unified Parkinson's Disease Rating Scale part III (UPDRS-III), and assessment of motor and non-motor symptoms using standardized clinical scales. The relationships between hypomimia and other clinical data were analysed using Mann-Whitney U-tests and regression analysis. RESULTS: Hypomimia occurred in up to 70% of patients with PD. Patients with hypomimia had worse UPDRS-III 'off-medication' scores, mainly driven by bradykinesia and rigidity subscores. Patients with hypomimia also had worse apathy than patients without hypomimia. Finally, we found that hypomimia was levodopa-responsive and its improvement mirrored the change by levodopa in axial motor symptoms. CONCLUSION: Our study provides novel information regarding the clinical correlates of hypomimia in people with PD. A better understanding of hypomimia may be relevant for improving treatment and quality of life in PD.

Contingent negative variation: a biomarker of abnormal attention in functional movement disorders.

BACKGROUND AND PURPOSE: Contingent negative variation (CNV) is a negative cortical wave that precedes a pre-cued imperative stimulus requiring a quick motor response. It has been related to motor preparation and anticipatory attention. The aim was to ascertain whether the clinical improvement of functional movement disorders after physiotherapy would be associated with faster reaction times and modulation of CNV. METHODS: Motor performance and CNV were analysed during a pre-cued choice reaction time task with varying cue validity. Twenty-one patients with functional movement disorders and 13 healthy controls at baseline were compared. Patients then underwent physiotherapy. At follow-up after physiotherapy, patients were categorized as clinically improved (responders) or not improved (non-responders) and retested. RESULTS: At baseline, patients did not generate CNV, contrary to controls [mean amplitude (µV) at the end of preparation to move: patients -0.47 (95% CI -1.94, 1.00) versus controls -2.59 (95% CI -4.46, -0.72)]. Responders performed faster after physiotherapy [mean natural logarithm (ln) reaction time (RT) (ms): follow-up 6.112 (95% CI 5.923, 6.301) versus baseline 6.206 (95% CI 6.019, 6.394), P = 0.010], contrary to non-responders. Simultaneously, responders showed a recovery of CNV after physiotherapy [follow-up -1.95 (95% CI -3.49, -0.41) versus baseline -0.19 (95% CI -1.73, 1.35), P < 0.001], contrary to non-responders [follow-up -0.32 (95% CI -1.79, 1.14) versus baseline -0.72 (95% CI -2.19, 0.75), P = 0.381]. CONCLUSIONS: Clinical improvement of functional movement disorders after physiotherapy was associated with faster reaction times and normalization of CNV, which was absent at baseline. These findings suggest that CNV may constitute a useful neurophysiological biomarker related to abnormal attention in functional movement disorders.

Randomised feasibility study of physiotherapy for patients with functional motor symptoms.

OBJECTIVE: To determine the feasibility of conducting a randomised controlled trial of a specialist physiotherapy intervention for functional motor symptoms (FMS). METHODS: A randomised feasibility study was conducted recruiting patients with a clinically established diagnosis of FMS from a tertiary neurology clinic in London, UK. Participants were randomised to the intervention or a treatment as usual control. Measures of feasibility and clinical outcome were collected and assessed at 6 months. RESULTS: 60 individuals were recruited over a 9-month period. Three withdrew, leaving 29 intervention and 28 controls participants in the final analysis. 32% of patients with FMS met the inclusion criteria, of which 90% enrolled. Acceptability of the intervention was high and there were no adverse events. At 6 months, 72% of the intervention group rated their symptoms as improved, compared to 18% in the control group. There was a moderate to large treatment effect across a range of outcomes, including three of eight Short Form 36 (SF36) domains (d=0.46-0.79). The SF36 Physical function was found to be a suitable primary outcome measure for a future trial; adjusted mean difference 19.8 (95% CI 10.2 to 29.5). The additional quality adjusted life years (QALY) with intervention was 0.08 (95% CI 0.03 to 0.13), the mean incremental cost per QALY gained was £12 087. CONCLUSIONS: This feasibility study demonstrated high rates of recruitment, retention and acceptability. Clinical effect size was moderate to large with high probability of being cost-effective. A randomised controlled trial is needed. TRIAL REGISTRATION NUMBER: NCT02275000; Results.

High rates of clinically relevant incidental findings by total-body CT scanning in trauma patients; results of the REACT-2 trial.

OBJECTIVES: To determine whether there is a difference in frequency and clinical relevance of incidental findings detected by total-body computed tomography scanning (TBCT) compared to those by the standard work-up (STWU) with selective computed tomography (CT) scanning. METHODS: Trauma patients from five trauma centres were randomized between April 2011 and January 2014 to TBCT imaging or STWU consisting of conventional imaging with selective CT scanning. Incidental findings were divided into three categories: 1) major finding, may cause mortality; 2) moderate finding, may cause morbidity; and 3) minor finding, hardly relevant. Generalized estimating equations were applied to assess differences in incidental findings. RESULTS: In total, 1083 patients were enrolled, of which 541 patients (49.9 %) were randomized for TBCT and 542 patients (50.1 %) for STWU. Major findings were detected in 23 patients (4.3 %) in the TBCT group compared to 9 patients (1.7 %) in the STWU group (adjusted rate ratio 2.851; 95%CI 1.337-6.077; p < 0.007). Findings of moderate relevance were detected in 120 patients (22.2 %) in the TBCT group compared to 86 patients (15.9 %) in the STWU group (adjusted rate ratio 1.421; 95%CI 1.088-1.854; p < 0.010). CONCLUSIONS: Compared to selective CT scanning, more patients with clinically relevant incidental findings can be expected by TBCT scanning. KEY POINTS: • Total-body CT scanning in trauma results in 1.5 times more incidental findings. • Evaluation by TBCT in trauma results in more patients with incidental findings. • In every category of clinical relevance, TBCT detects more incidental findings.

Mind the gap: temporal discrimination and dystonia.

BACKGROUND AND PURPOSE: One of the most widely studied perceptual measures of sensory dysfunction in dystonia is the temporal discrimination threshold (TDT) (the shortest interval at which subjects can perceive that there are two stimuli rather than one). However the elevated thresholds described may be due to a number of potential mechanisms as current paradigms test not only temporal discrimination but also extraneous sensory and decision-making parameters. In this study two paradigms designed to better quantify temporal processing are presented and a decision-making model is used to assess the influence of decision strategy. METHODS: 22 patients with cervical dystonia and 22 age-matched controls completed two tasks (i) temporal resolution (a randomized, automated version of existing TDT paradigms) and (ii) interval discrimination (rating the length of two consecutive intervals). RESULTS: In the temporal resolution task patients had delayed (P = 0.021) and more variable (P = 0.013) response times but equivalent discrimination thresholds. Modelling these effects suggested this was due to an increased perceptual decision boundary in dystonia with patients requiring greater evidence before committing to decisions (P = 0.020). Patient performance on the interval discrimination task was normal. CONCLUSIONS: Our work suggests that previously observed abnormalities in TDT may not be due to a selective sensory deficit of temporal processing as decision-making itself is abnormal in cervical dystonia.

Generation and Beaming of Early Hot Electrons onto the Capsule in Laser-Driven Ignition Hohlraums.

In hohlraums for inertial confinement fusion (ICF) implosions on the National Ignition Facility, suprathermal hot electrons, generated by laser plasma instabilities early in the laser pulse ("picket") while blowing down the laser entrance hole (LEH) windows, can preheat the capsule fuel. Hard x-ray imaging of a Bi capsule surrogate and of the hohlraum emissions, in conjunction with the measurement of time-resolved bremsstrahlung spectra, allows us to uncover for the first time the directionality of these hot electrons and infer the capsule preheat. Data and Monte Carlo calculations indicate that for most experiments the hot electrons are emitted nearly isotropically from the LEH. However, we have found cases where a significant fraction of the generated electrons are emitted in a collimated beam directly towards the capsule poles, where their local energy deposition is up to 10× higher than the average preheat value and acceptable levels for ICF implosions. The observed "beaming" is consistent with a recently unveiled multibeam stimulated Raman scattering model [P. Michel et al., Phys. Rev. Lett. 115, 055003 (2015)], where laser beams in a cone drive a common plasma wave on axis. Finally, we demonstrate that we can control the amount of generated hot electrons by changing the laser pulse shape and hohlraum plasma.

Abnormal movement-related suppression of sensory evoked potentials in upper limb dystonia.

BACKGROUND: Gating of sensory evoked potentials (SEPs) around the onset of a voluntary movement is a physiological phenomenon with centripetal and central components, and may reflect sensorimotor integration required for normal movement control. OBJECTIVE: Our objective was the investigation of SEP suppression at the onset of movement and the interaction between SEP suppression and vibration of the limb. METHODS: Fourteen patients with primary focal/segmental dystonia and 17 age-matched healthy volunteers were studied. SEPs were elicited after electrical stimulation of the median nerve at the wrist. Electroencephalograms (EEGs) were recorded over the scalp at three sites according to the International 10-20 System (F3, C3 and P3). SEPs were recorded in four conditions: at rest, at the onset of movement (a self-paced abduction movement of the right thumb), both in the absence and in the presence of vibration of the limb. RESULTS: Repeated measures anova revealed that there was a significant main effect of group [F(1, 11.1) = 0.471, P = 0.002]. Post hoc exploration of this effect revealed it to be due to an absence of SEP suppression at movement onset in patients (mean ratio SEP movement onset/rest 1.15 at F3, 1.13 at C3, 1.01 at P3) compared to controls, who had SEP suppression at movement onset (mean ratio SEP movement onset/rest 0.79 at F3, 0.78 at C3, 0.77 at P3). With vibration, SEP suppression reduced in both patients and controls to a similar extent. CONCLUSION: These results demonstrate abnormal SEP suppression at the onset of movement in patients with primary dystonia, and in addition that vibration of the limb reduces SEP suppression in patients and controls.

Process evaluation of the Bristol girls dance project.

BACKGROUND: The Bristol Girls Dance Project was a cluster randomised controlled trial that aimed to increase objectively measured moderate-to-vigorous physical activity (MVPA) levels of Year 7 (age 11-12) girls through a dance-based after-school intervention. The intervention was delivered in nine schools and consisted of up to forty after-school dance sessions. This paper reports on the main findings from the detailed process evaluation that was conducted. METHODS: Quantitative and qualitative data were collected from intervention schools. Dose and fidelity were reported by dance instructors at every session. Intervention dose was defined as attending two thirds of sessions and was measured by attendance registers. Fidelity to the intervention manual was reported by dance instructors. On four randomly-selected occasions, participants reported their perceived level of exertion and enjoyment. Reasons for non-attendance were self-reported at the end of the intervention. Semi-structured interviews were conducted with all dance instructors who delivered the intervention (n = 10) and school contacts (n = 9) in intervention schools. A focus group was conducted with girls who participated in each intervention school (n = 9). RESULTS: The study did not affect girls' MVPA. An average of 31.7 girls participated in each school, with 9.1 per school receiving the intervention dose. Mean attendance and instructors' fidelity to the intervention manual decreased over time. The decline in attendance was largely attributed to extraneous factors common to after-school activities. Qualitative data suggest that the training and intervention manual were helpful to most instructors. Participant ratings of session enjoyment were high but perceived exertion was low, however, girls found parts of the intervention challenging. CONCLUSIONS: The intervention was enjoyed by participants. Attendance at the intervention sessions was low but typical of after-school activities. Participants reported that the intervention brought about numerous health and social benefits and improved their dance-based knowledge and skills. The intervention could be improved by reducing the number of girls allowed to participate in each school and providing longer and more in-depth training to those delivering the intervention. TRIAL REGISTRATION: ISRCTN52882523 Registered 25th April 2013.

Alpha Heating and Burning Plasmas in Inertial Confinement Fusion.

Estimating the level of alpha heating and determining the onset of the burning plasma regime is essential to finding the path towards thermonuclear ignition. In a burning plasma, the alpha heating exceeds the external input energy to the plasma. Using a simple model of the implosion, it is shown that a general relation can be derived, connecting the burning plasma regime to the yield enhancement due to alpha heating and to experimentally measurable parameters such as the Lawson ignition parameter. A general alpha-heating curve is found, independent of the target and suitable to assess the performance of all laser fusion experiments whether direct or indirect drive. The onset of the burning plasma regime inside the hot spot of current implosions on the National Ignition Facility requires a fusion yield of about 50 kJ.

Demonstration of High Performance in Layered Deuterium-Tritium Capsule Implosions in Uranium Hohlraums at the National Ignition Facility.

We report on the first layered deuterium-tritium (DT) capsule implosions indirectly driven by a "high-foot" laser pulse that were fielded in depleted uranium hohlraums at the National Ignition Facility. Recently, high-foot implosions have demonstrated improved resistance to ablation-front Rayleigh-Taylor instability induced mixing of ablator material into the DT hot spot [Hurricane et al., Nature (London) 506, 343 (2014)]. Uranium hohlraums provide a higher albedo and thus an increased drive equivalent to an additional 25 TW laser power at the peak of the drive compared to standard gold hohlraums leading to higher implosion velocity. Additionally, we observe an improved hot-spot shape closer to round which indicates enhanced drive from the waist. In contrast to findings in the National Ignition Campaign, now all of our highest performing experiments have been done in uranium hohlraums and achieved total yields approaching 10^{16} neutrons where more than 50% of the yield was due to additional heating of alpha particles stopping in the DT fuel.

Improved Performance of High Areal Density Indirect Drive Implosions at the National Ignition Facility using a Four-Shock Adiabat Shaped Drive.

Hydrodynamic instabilities can cause capsule defects and other perturbations to grow and degrade implosion performance in ignition experiments at the National Ignition Facility (NIF). Here, we show the first experimental demonstration that a strong unsupported first shock in indirect drive implosions at the NIF reduces ablation front instability growth leading to a 3 to 10 times higher yield with fuel ρR>1 g/cm(2). This work shows the importance of ablation front instability growth during the National Ignition Campaign and may provide a path to improved performance at the high compression necessary for ignition.

Thin shell, high velocity inertial confinement fusion implosions on the national ignition facility.

Experiments have recently been conducted at the National Ignition Facility utilizing inertial confinement fusion capsule ablators that are 175 and 165 µm in thickness, 10% and 15% thinner, respectively, than the nominal thickness capsule used throughout the high foot and most of the National Ignition Campaign. These three-shock, high-adiabat, high-foot implosions have demonstrated good performance, with higher velocity and better symmetry control at lower laser powers and energies than their nominal thickness ablator counterparts. Little to no hydrodynamic mix into the DT hot spot has been observed despite the higher velocities and reduced depth for possible instability feedthrough. Early results have shown good repeatability, with up to 1/2 the neutron yield coming from α-particle self-heating.

A positive diagnosis of functional (psychogenic) tics.

BACKGROUND AND PURPOSE: Functional tics, also called psychogenic tics or pseudo-tics, are difficult to diagnose because of the lack of diagnostic criteria and their clinical similarities to organic tics. The aim of the present study was to report a case series of patients with documented functional tics and to describe their clinical characteristics, risk factors and psychiatric comorbidity. Also clinical tips are suggested which might help the differential diagnosis in clinical practice. METHODS AND RESULTS: Eleven patients (mean age at onset 37.2, SD 13.5; three females) were included with a documented or clinically established diagnosis of functional tics, according to consultant neurologists who have specific expertise in functional movement disorders or in tic disorders. Adult onset, absent family history of tics, inability to suppress the movements, lack of premonitory sensations, absence of pali-, echo- and copro-phenomena, presence of blocking tics, the lack of the typical rostrocaudal tic distribution and the coexistence of other functional movement disorders were common in our patients. CONCLUSIONS: Our data suggest that functional tics can be differentiated from organic tics on clinical grounds, although it is also accepted that this distinction can be difficult in certain cases. Clinical clues from history and examination described here might help to identify patients with functional tics.

All in the blink of an eye: new insight into cerebellar and brainstem function in DYT1 and DYT6 dystonia.

BACKGROUND AND PURPOSE: Traditionally dystonia has been considered a disorder of basal ganglia dysfunction. However, recent research has advocated a more complex neuroanatomical network. In particular, there is increasing interest in the pathophysiological role of the cerebellum. Patients with cervical and focal hand dystonia have impaired cerebellar associative learning using the paradigm eyeblink conditioning. This is perhaps the most direct evidence to date that the cerebellum is implicated in patients. METHODS: Eleven patients with DYT1 dystonia and five patients with DYT6 dystonia were examined and rates of eyeblink conditioning were compared with age-matched controls. A marker of brainstem excitability, the blink reflex recovery, was also studied in the same groups. RESULTS: Patients with DYT1 and DYT6 dystonia have a normal ability to acquire conditioned responses. Blink reflex recovery was enhanced in DYT1 but this effect was not seen in DYT6. CONCLUSIONS: If the cerebellum is an important driver in DYT1 and DYT6 dystonia our data suggest that there is specific cerebellar dysfunction such that the circuits essential for conditioning function normally. Our data are contrary to observations in focal dystonia and suggest that the cerebellum may have a distinct role in different subsets of dystonia. Evidence of enhanced blink reflex recovery in all patients with dystonia was not found and recent studies calling for the blink recovery reflex to be used as a diagnostic test for dystonic tremor may require further corroboration.

2D X-ray radiography of imploding capsules at the national ignition facility.

First measurements of the in-flight shape of imploding inertial confinement fusion (ICF) capsules at the National Ignition Facility (NIF) were obtained by using two-dimensional x-ray radiography. The sequence of area-backlit, time-gated pinhole images is analyzed for implosion velocity, low-mode shape and density asymmetries, and the absolute offset and center-of-mass velocity of the capsule shell. The in-flight shell is often observed to be asymmetric even when the concomitant core self-emission is round. A ∼ 15 µm shell asymmetry amplitude of the Y(40) spherical harmonic mode was observed for standard NIF ICF hohlraums at a shell radius of ∼ 200 µm (capsule at ∼ 5× radial compression). This asymmetry is mitigated by a ∼ 10% increase in the hohlraum length.