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.

Proof-of-Principle Experiment on the Dynamic Shell Formation for Inertial Confinement Fusion.

In the dynamic-shell (DS) concept [V. N. Goncharov et al., Novel Hot-Spot Ignition Designs for Inertial Confinement Fusion with Liquid-Deuterium-Tritium Spheres, Phys. Rev. Lett. 125, 065001 (2020).PRLTAO0031-900710.1103/PhysRevLett.125.065001] for laser-driven inertial confinement fusion the deuterium-tritium fuel is initially in the form of a homogeneous liquid inside a wetted-foam spherical shell. This fuel is ignited using a conventional implosion, which is preceded by a initial compression of the fuel followed by its expansion and dynamic formation of a high-density fuel shell with a low-density interior. This Letter reports on a scaled-down, proof-of-principle experiment on the OMEGA laser demonstrating, for the first time, the feasibility of DS formation. A shell is formed by convergent shocks launched by laser pulses at the edge of a plasma sphere, with the plasma itself formed as a result of laser-driven compression and relaxation of a surrogate plastic-foam ball target. Three x-ray diagnostics, namely, 1D spatially resolved self-emission streaked imaging, 2D self-emission framed imaging, and backlighting radiography, have shown good agreement with the predicted evolution of the DS and its stability to low Legendre mode perturbations introduced by laser irradiation and target asymmetries.

Spontaneous shunt independence in paediatric tumour-related hydrocephalus: case series and review of the literature.

PURPOSE: Hydrocephalus is commonly associated with paediatric posterior fossa tumours and their resection. This is commonly managed by ventriculoperitoneal shunt insertion, which is associated with a lifelong risk of malfunction, necessitating revisional surgery. Few opportunities ever arise for the patient to be free of the shunt and this risk. We describe three patients shunted for tumour-related hydrocephalus who subsequently developed spontaneous shunt independence. We discuss this in the context of the literature. METHODS: A single-centre retrospective case series analysis was performed using a departmental database. Case notes were retrieved from a local electronic records database, and images were reviewed using national Picture Archiving and Communication Systems. RESULTS: Over a 10-year period, 28 patients underwent ventriculoperitoneal shunt insertion for tumour-related hydrocephalus. Of these, 3 patients (10.7%) went on to have their shunts successfully removed. Age at presentation varied from 1 to 16 years. In all cases, the patient required shunt externalization due to shunt or intra-abdominal infection. This was used as an opportunity to challenge the need for ongoing cerebrospinal fluid (CSF) diversion. In one case, this occurred only several months after a shunt blockage with intracranial pressure monitoring that proved her shunt dependence. All three patients tolerated this challenge, their shunt systems were removed without complication, and they remain free of hydrocephalus at last follow-up. CONCLUSION: These cases reflect our poor understanding of the heterogenous physiology of patients with shunted hydrocephalus and underline the importance of challenging the need for CSF diversion at any appropriate opportunity.

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.

CELPI: trial protocol for a randomised controlled trial of a Carer End of Life Planning Intervention in people dying with dementia.

BACKGROUND: Dementia is a leading cause of death in developed nations. Despite an often distressing and symptom laden end of life, there are systematic barriers to accessing palliative care in older people dying of dementia. Evidence exists that 70% of people living with severe dementia attend an emergency department (ED) in their last year of life. The aim of this trial is to test whether a Carer End of Life Planning Intervention (CELPI), co-designed by consumers, clinicians and content specialists, improves access to end of life care for older people with severe dementia, using an ED visit as a catalyst for recognising unmet needs and specialist palliative care referral where indicated. METHODS: A randomised controlled trial (RCT) enrolling at six EDs across three states in Australia will be conducted, enrolling four hundred and forty dyads comprising a person with severe dementia aged ≥ 65 years, and their primary carer. Participants will be randomly allocated to CELPI or the control group. CELPI incorporates a structured carer needs assessment and referral to specialist palliative care services where indicated by patient symptom burden and needs assessment. The primary outcome measure is death of the person with dementia in the carer-nominated preferred location. Secondary outcomes include carer reported quality of life of the person dying of dementia, hospital bed day occupancy in the last 12 months of life, and carer stress. An economic evaluation from the perspective of a health funder will be conducted. DISCUSSION: CELPI seeks to support carers and provide optimal end of life care for the person dying of dementia. This trial will provide high level evidence as to the clinical and cost effectiveness of this intervention. TRIAL REGISTRATION: ACTRN12622000611729 registered 22/04/2022.

Insight into the effects of confined hydrocarbon species on the lifetime of methanol conversion catalysts.

The methanol-to-hydrocarbons reaction refers collectively to a series of important industrial catalytic processes to produce either olefins or gasoline. Mechanistically, methanol conversion proceeds through a 'pool' of hydrocarbon species. For the methanol-to-olefins process, these species can be delineated broadly into 'desired' lighter olefins and 'undesired' heavier fractions that cause deactivation in a matter of hours. The crux in further catalyst optimization is the ability to follow the formation of carbonaceous species during operation. Here, we report the combined results of an operando Kerr-gated Raman spectroscopic study with state-of-the-art operando molecular simulations, which allowed us to follow the formation of hydrocarbon species at various stages of methanol conversion. Polyenes are identified as crucial intermediates towards formation of polycyclic aromatic hydrocarbons, with their fate determined largely by the zeolite topology. Notably, we provide the missing link between active and deactivating species, which allows us to propose potential design rules for future-generation catalysts.

Direct Measurements of DT Fuel Preheat from Hot Electrons in Direct-Drive Inertial Confinement Fusion.

Hot electrons generated by laser-plasma instabilities degrade the performance of laser-fusion implosions by preheating the DT fuel and reducing core compression. The hot-electron energy deposition in the DT fuel has been directly measured for the first time by comparing the hard x-ray signals between DT-layered and mass-equivalent ablator-only implosions. The electron energy deposition profile in the fuel is inferred through dedicated experiments using Cu-doped payloads of varying thickness. The measured preheat energy accurately explains the areal-density degradation observed in many OMEGA implosions. This technique can be used to assess the viability of the direct-drive approach to laser fusion with respect to the scaling of hot-electron preheat with laser energy.

Experimentally Inferred Fusion Yield Dependencies of OMEGA Inertial Confinement Fusion Implosions.

Statistical modeling of experimental and simulation databases has enabled the development of an accurate predictive capability for deuterium-tritium layered cryogenic implosions at the OMEGA laser [V. Gopalaswamy et al.,Nature 565, 581 (2019)10.1038/s41586-019-0877-0]. In this letter, a physics-based statistical mapping framework is described and used to uncover the dependencies of the fusion yield. This model is used to identify and quantify the degradation mechanisms of the fusion yield in direct-drive implosions on OMEGA. The yield is found to be reduced by the ratio of laser beam to target radius, the asymmetry in inferred ion temperatures from the ℓ=1 mode, the time span over which tritium fuel has decayed, and parameters related to the implosion hydrodynamic stability. When adjusted for tritium decay and ℓ=1 mode, the highest yield in OMEGA cryogenic implosions is predicted to exceed 2×10^{14} fusion reactions.

Atomic layer deposited Al2O3passivation layer for few-layer WS2field effect transistors.

We have investigated the effect of an Al2O3passivation layer on the performance of few-layer WS2FETs. While the performance of WS2FETs is often limited by a substantial decrease in carrier mobility owing to charged impurities and a Schottky barrier between the WS2and metal electrodes, the introduction of an Al2O3overlayer by atomic layer deposition (ALD) suppressed the influence of charged impurities by high-κdielectric screening effect and reduced the effective Schottky barrier height. We argue that n-doping of WS2, induced by positive fixed charges formed at Al2O3/WS2interface during the ALD process, is responsible for the reduction of the effective Schottky barrier height in the devices. In addition, the Al2O3passivation layer protected the device from oxidation, and maintained stable electrical performance of the WS2FETs over 57 d. Thus, the ALD of Al2O3overlayer provides a facile method to enhance the performance of WS2FETs and to ensure ambient stability.

Fast electron transport dynamics and energy deposition in magnetized, imploded cylindrical plasma.

Inertial confinement fusion approaches involve the creation of high-energy-density states through compression. High gain scenarios may be enabled by the beneficial heating from fast electrons produced with an intense laser and by energy containment with a high-strength magnetic field. Here, we report experimental measurements from a configuration integrating a magnetized, imploded cylindrical plasma and intense laser-driven electrons as well as multi-stage simulations that show fast electrons transport pathways at different times during the implosion and quantify their energy deposition contribution. The experiment consisted of a CH foam cylinder, inside an external coaxial magnetic field of 5 T, that was imploded using 36 OMEGA laser beams. Two-dimensional (2D) hydrodynamic modelling predicts the CH density reaches [Formula: see text], the temperature reaches 920 eV and the external B-field is amplified at maximum compression to 580 T. At pre-determined times during the compression, the intense OMEGA EP laser irradiated one end of the cylinder to accelerate relativistic electrons into the dense imploded plasma providing additional heating. The relativistic electron beam generation was simulated using a 2D particle-in-cell (PIC) code. Finally, three-dimensional hybrid-PIC simulations calculated the electron propagation and energy deposition inside the target and revealed the roles the compressed and self-generated B-fields play in transport. During a time window before the maximum compression time, the self-generated B-field on the compression front confines the injected electrons inside the target, increasing the temperature through Joule heating. For a stronger B-field seed of 20 T, the electrons are predicted to be guided into the compressed target and provide additional collisional heating. This article is part of a discussion meeting issue 'Prospects for high gain inertial fusion energy (part 2)'.

Direct-drive laser fusion: status, plans and future.

Laser-direct drive (LDD), along with laser indirect (X-ray) drive (LID) and magnetic drive with pulsed power, is one of the three viable inertial confinement fusion approaches to achieving fusion ignition and gain in the laboratory. The LDD programme is primarily being executed at both the Omega Laser Facility at the Laboratory for Laser Energetics and at the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory. LDD research at Omega includes cryogenic implosions, fundamental physics including material properties, hydrodynamics and laser-plasma interaction physics. LDD research on the NIF is focused on energy coupling and laser-plasma interactions physics at ignition-scale plasmas. Limited implosions on the NIF in the 'polar-drive' configuration, where the irradiation geometry is configured for LID, are also a feature of LDD research. The ability to conduct research over a large range of energy, power and scale size using both Omega and the NIF is a major positive aspect of LDD research that reduces the risk in scaling from OMEGA to megajoule-class lasers. The paper will summarize the present status of LDD research and plans for the future with the goal of ultimately achieving a burning plasma in the laboratory. This article is part of a discussion meeting issue 'Prospects for high gain inertial fusion energy (part 2)'.

Enhancing titre and production stability of paenibacillin from Paenibacillus polymyxa by sequential drug resistance screening.

AIMS: Paenibacillin is a naturally biosynthesized antimicrobial lantibiotic peptide which is produced by wild-type Paenibacillus polymyxa OSY-DF in low but detectable levels. The aim was to increase paenibacillin titre and production consistency through sequential drug resistance screening. METHODS AND RESULTS: Spontaneous mutants of P. polymyxa OSY-DF were isolated by subjecting the bacterium to two rounds of screening for resistance to rifampicin, which targets RNA polymerase, and gentamicin, which targets ribosomes. Changes in antimicrobial production of the mutants were monitored using a bioassay method. A spontaneous mutant, P. polymyxa OSY-EC, capable of producing high paenibacillin titre, was selected and compared phenotypically to the wild-type strain. The mutant was found to produce paenibacillin at five-fold higher titre than the wild type. The mutant constantly produced paenibacillin while the wild type produced the antimicrobial agent variably. Fourier transformation mid-infrared spectroscopy revealed an interclass distance of 6·4 between the wild type and the mutant strain, suggesting significant phenotypic change during the mutation. CONCLUSIONS: P. polymyxa OSY-EC, a spontaneous mutant capable of consistent production of high paenibacillin titre, was isolated from the wild type after sequential screening on rationally selected antibiotics. SIGNIFICANCE AND IMPACT OF THE STUDY: The study will help make paenibacillin available for large-scale testing by interested researchers and industries seeking applications that improve food safety and quality.

Laboratory confirmation of C60(+) as the carrier of two diffuse interstellar bands.

The diffuse interstellar bands are absorption lines seen towards reddened stars. None of the molecules responsible for these bands have been conclusively identified. Two bands at 9,632 ångströms and 9,577 ångströms were reported in 1994, and were suggested to arise from C60(+) molecules (ref. 3), on the basis of the proximity of these wavelengths to the absorption bands of C60(+) measured in a neon matrix. Confirmation of this assignment requires the gas-phase spectrum of C60(+). Here we report laboratory spectroscopy of C60(+) in the gas phase, cooled to 5.8 kelvin. The absorption spectrum has maxima at 9,632.7 ± 0.1 ångströms and 9,577.5 ± 0.1 ångströms, and the full widths at half-maximum of these bands are 2.2 ± 0.2 ångströms and 2.5 ± 0.2 ångströms, respectively. We conclude that we have positively identified the diffuse interstellar bands at 9,632 ångströms and 9,577 ångströms as arising from C60(+) in the interstellar medium.

Opening and closure of intraventricular neuroendoscopic procedures in infants under 1 year of age: institutional technique, case series and review of the literature.

PURPOSE: Intraventricular neuroendoscopic techniques, particularly third ventriculostomy, are employed increasingly in the management of infantile hydrocephalus. However, surgical access to the ventricular cavities is associated with a risk of post-operative cerebrospinal fluid (CSF) leak. Here, we describe a structured, multi-layered approach to wound opening and closure which aims to maximise the natural tissue barriers against CSF leakage. We present a series of patients undergoing this technique and subsequently review the literature regarding opening and closure techniques in paediatric intraventricular neuroendoscopic procedures. METHODS: We performed a retrospective case series analysis of patients under 1 year of age who underwent intraventricular neuroendoscopic procedures in a single institution over a 5-year period. Patients were identified from an institutional operative database, and operation notes and clinical records were subsequently reviewed. RESULTS: 28 patients fulfilled the inclusion criteria for this study. The mean age at operation was 9 weeks. 27 patients underwent endoscopic third ventriculostomy whilst 1 underwent endoscopic septostomy, and all patients underwent our structured, multi-layered opening and closure technique. Follow-up ranged from 4 months to 5 years. There were no cases of post-operative CSF leak, infection or wound breakdown. 12 patients remained shunt-free at the last follow-up, with the remaining 16 requiring shunt insertion for progressive hydrocephalus at a mean of 24 days post-operatively. CONCLUSION: Various methods aiming to prevent post-operative CSF leak have been reported in the literature. We propose that our institutional technique may be of benefit in minimising this risk in infants undergoing endoscopic third ventriculostomy and similar intraventricular neuroendoscopic procedures.

Thin-film perfect infrared absorbers over single- and dual-band atmospheric windows.

A thin-film perfect electromagnetic absorber with a tunable response in the infrared (IR) region is proposed using a metal-dielectric-metal configuration, which consists of a Ti top layer and a Ge spacer layer on a Ti substrate. The thin-film structure simplifies the absorber design by tuning the thicknesses of the two layers, which is suitable for large-scale fabrication by matured deposition technologies. The absorber supports perfect IR absorption with tunability from 3 µm to over 15 µm. Furthermore, the total thickness is much smaller than the wavelength, and the absorption has small iridescence. Based on this design, we demonstrated two samples with one supporting single-band absorption in the atmospheric absorption window (5-8 µm) and the other one supporting dual-band absorption in the two atmospheric transmission windows (3-5 and 8-13 µm). These absorption signatures can find applications in IR invisibility and radiative cooling.

Novel Hot-Spot Ignition Designs for Inertial Confinement Fusion with Liquid-Deuterium-Tritium Spheres.

A new class of ignition designs is proposed for inertial confinement fusion experiments. These designs are based on the hot-spot ignition approach, but instead of a conventional target that is comprised of a spherical shell with a thin frozen deuterium-tritium (DT) layer, a liquid DT sphere inside a wetted-foam shell is used, and the lower-density central region and higher-density shell are created dynamically by appropriately shaping the laser pulse. These offer several advantages, including simplicity in target production (suitable for mass production for inertial fusion energy), absence of the fill tube (leading to a more-symmetric implosion), and lower sensitivity to both laser imprint and physics uncertainty in shock interaction with the ice-vapor interface. The design evolution starts by launching an ∼1-Mbar shock into a DT sphere. After bouncing from the center, the reflected shock reaches the outer surface of the sphere and the shocked material starts to expand outward. Supporting ablation pressure ultimately stops such expansion and subsequently launches a shock toward the target center, compressing the ablator and fuel, and forming a shell. The shell is then accelerated and fuel is compressed by appropriately shaping the drive laser pulse, forming a hot spot using the conventional or shock ignition approaches. This Letter demonstrates the feasibility of the new concept using hydrodynamic simulations and discusses the advantages and disadvantages of the concept compared with more-traditional inertial confinement fusion designs.

Correlates of the Abnormal Involuntary Movement Scale in Veterans With Tardive Dyskinesia.

PURPOSE/BACKGROUND: To add to limited evidence on the Abnormal Involuntary Movement Scale (AIMS) as a measure of tardive dyskinesia (TD) in clinical practice settings, the characteristics and correlates of AIMS scores were assessed. METHODS/PROCEDURES: Veterans with schizophrenia/schizoaffective, bipolar, or major depressive disorders receiving antipsychotics and at least 1 AIMS score during October 1, 2014, to September 30, 2015, were identified. Tardive dyskinesia was determined by the International Classification of Diseases, Ninth Revision, Clinical Modification, codes. Correlates of AIMS scores were examined using χ or t tests. Odds ratios and ß parameters with 95% confidence intervals for categorical and continuous variables associated with AIMS scores were derived from a multivariate logistic and linear regression, respectively. FINDINGS/RESULTS: Among 7985 veterans receiving antipsychotics, only 4706 (58.9%) had at least 1 AIMS examination. Of these, 229 (4.9%) were diagnosed with possible TD. The mean total AIMS scores and AIMS awareness/incapacitation scores were significantly higher for patients with TD (both P < 0.0001). Comparing diagnostic threshold criteria of AIMS ratings, only 17.5% to 37.1% of veterans with TD were successfully identified. Among TD patients, 21.4% had a total score of moderate-severe and 15.3% had ratings of at least mild movements in 2 or more body regions. In the regression analyses, being older, African-American, having schizophrenia/schizoaffective disorder, and receiving antipsychotics or benztropine significantly increased the severity of AIMS scores. Higher AIMS scores were not predictive of outcomes other than marital status in socioeconomic or healthcare domains. IMPLICATIONS/CONCLUSIONS: Although the AIMS is essential for TD research, its value in clinical practice without training and oversight remains unclear. Efforts to adapt screening procedures to clinical needs may be worthwhile.

Cumulative Burden of Illness in Veterans With Tardive Dyskinesia and Serious Mental Disorders.

PURPOSE/BACKGROUND: To inform cost-benefit decisions for veterans, the risk of tardive dyskinesia (TD) and its impact on comorbidities and outcomes were assessed. METHODS/PROCEDURES: In a retrospective study, veterans with schizophrenia/schizoaffective, and bipolar and major depressive disorders receiving antipsychotics during the period October 1, 2014, to September 30, 2015, were identified. Tardive dyskinesia was determined by International Classification of Diseases, Ninth Revision, Clinical Modification codes. Correlates of TD were examined using χ or t tests. Odds ratios (ORs) and ß parameters with 95% confidence intervals (CIs) for categorical and continuous variables associated with TD were derived from a multivariate logistic and linear regression, respectively. FINDINGS/RESULTS: Among 7985 veterans, 332 (4.2%) were diagnosed as having possible TD. The odds of having TD were higher for older veterans (OR, 1.04; 95% CI, 1.03-1.05; P < 0.0001) and veterans with schizophrenia/schizoaffective disorder (OR, 1.54; 95% CI, 1.23-1.91; P < 0.0001) or diabetes (OR, 1.64; 95% CI, 1.30-2.06; P < 0.0001). Veterans with TD received more antipsychotic prescriptions (mean ± SD, 18.4 ± 30.3 vs 13.3 ± 26.4; P = 0.003) and days of supply (233.9 ± 95.4 vs 211.4 ± 102.0; P < 0.0001). They were more likely to have received 2 or more antipsychotics (27.1% vs 19.7%, P = 0.0009) and benztropine (OR, 2.25: 95% CI 1.73-2.91; P < 0.0001). Veterans with TD had a higher Charlson Comorbidity Index score (ß = 0.32; SE, 0.09; 95% CI, 0.14-0.49; P = 0.0003) and higher odds of any medical hospitalization (OR, 1.45; 95% CI, 1.07-1.95; P = 0.001). IMPLICATIONS/CONCLUSIONS: The diagnosis of possible TD was associated with older age, schizophrenia/schizoaffective disorder, medical comorbidity, and hospitalization. Tardive dyskinesia may be a marker for patients at risk of adverse health care outcomes and diminished quality of life.

Structural configurations and Raman spectra of carbon nanoscrolls.

Three types of carbon nanoscroll (CNS) structures that are formed when scrolling up graphene sheets are investigated using Raman spectroscopy and atomic force microscopy (AFM). The CNSs were produced from exfoliated monolayer graphene deposited on a Si chip by applying a droplet of isopropyl alcohol (IPA) solution. The three types of CNS are classified as single-elliptical-core, double-elliptical-core (both with large internal volumes) and collapsed ribbon-like, based on AFM surface profile measurements. We discuss the structure and formation of CNS with much larger hollow cores than is commonly assumed and relate this to the large effective 2D bending stiffness of graphene in the IPA solution. The large elliptical core structures show Raman spectra similar to those previously reported for CNS and indicate little interaction between the scrolled layers. The Raman spectra from ribbon-like structures show additional features that are similar to that of folded graphene. These new features can be related to layer breathing modes combined with some resonance enhancement at specific regions of the ribbon-like CNSs that are due to specific twist angles produced when the structure folds/collapses.

Broadband infrared plasmonic metamaterial absorber with multipronged absorption mechanisms.

A broadband plasmonic metamaterial absorber with near perfect multiband absorption in the infrared region is designed using a metal-insulator-metal configuration and fabricated using photolithography. The metal-insulator-metal configuration consists of a Ti microdisk array, a SiO2 insulator spacer, and an Al bottom layer. The multiband absorption occurs with near perfect absorption at 4.8-7.5 µm and 9.7-10.5 µm. Ultra-broadband absorption in the mid-IR wavelength range between 3-14 µm is realized by adding a rough photoresist layer on top of the periodic microdisk structures. The multiband absorption is achieved through the combined mechanisms including plasmonic surface lattice resonance, gap plasmon resonance, Fabry-Perot cavity resonance, and the intrinsic phonon-polariton absorption of SiO2.