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.

Dynamics and Power Balance of Near Unity Target Gain Inertial Confinement Fusion Implosions

The change in the power balance, temporal dynamics, emission weighted size, temperature, mass, and areal density of inertially confined fusion plasmas have been quantified for experiments that reach target gains up to 0.72. It is observed that as the target gain rises, increased rates of self-heating initially overcome expansion power losses. This leads to reacting plasmas that reach peak fusion production at later times with increased size, temperature, mass and with lower emission weighted areal densities. Analytic models are consistent with the observations and inferences for how these quantities evolve as the rate of fusion self-heating, fusion yield, and target gain increase. At peak fusion production, it is found that as temperatures and target gains rise, the expansion power loss increases to a near constant ratio of the fusion self-heating power. This is consistent with models that indicate that the expansion losses dominate the dynamics in this regime.

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.

Electron microscopic observations of Rb particles and pitting in 129Xe spin-exchange optical pumping cells

High-volume production of hyperpolarized ¹²⁹Xe by spin-exchange optical pumping (SEOP) has historically fallen short of theoretical predictions. Recently, this shortfall was proposed to be caused by the formation of alkali metal clusters during optical pumping. However, this hypothesis has yet to be verified experimentally. Here, we seek to detect the presence of alkali particles using a combination of both transmission (TEM) and scanning (SEM) electron microscopy. From TEM studies, we observe the presence of particles exhibiting sizes ranging from approximately 0.2 to 1 μm and present at densities of order 10 s of particles per 100 square microns. Particle formation was more closely associated with extensive cell usage history than short-term ([Formula: see text]1 h) SEOP exposure. From the SEM studies, we observe pits on the cell surface. These pits are remarkably smooth, were frequently found adjacent to Rb particles, and located predominantly on the front face of the cells; they range in size from 1 to 5 μm. Together, these findings suggest that Rb particles do form during the SEOP process and at times can impart sufficient energy to locally alter the Pyrex surface.

A study of CR-39 plastic charged-particle detector replacement by consumer imaging sensors

Consumer imaging sensors (CIS) are examined for real-time charged-particle detection and CR-39 plastic detector replacement. Removing cover glass from CIS is hard if not impossible, in particular for the latest inexpensive webcam models. We show that $10-class CIS are sensitive to MeV and higher energy protons and α-particles by using a ⁹⁰Sr β-source with its cover glass in place. Indirect, real-time, high-resolution detection is also feasible when combining CIS with a ZnS:Ag phosphor screen and optics. Noise reduction in CIS is nevertheless important for the indirect approach.

Characterizing and modeling the efficiency limits in large-scale production of hyperpolarized 129Xe

The ability to produce liter volumes of highly spin-polarized 129Xe enables a wide range of investigations, most notably in the fields of materials science and biomedical MRI. However, for nearly all polarizers built to date, both peak 129Xe polarization and the rate at which it is produced fall far below those predicted by the standard model of Rb metal vapor, spin-exchange optical pumping (SEOP). In this work, we comprehensively characterized a high-volume, flow-through 129Xe polarizer using three different SEOP cells with internal volumes of 100, 200 and 300 cc and two types of optical sources: a broad-spectrum 111-W laser (FWHM = 1.92 nm) and a line-narrowed 71-W laser (FWHM = 0.39 nm). By measuring 129Xe polarization as a function of gas flow rate, we extracted peak polarization and polarization production rate across a wide range of laser absorption levels. Peak polarization for all cells consistently remained a factor of 2-3 times lower than predicted at all absorption levels. Moreover, although production rates increased with laser absorption, they did so much more slowly than predicted by the standard theoretical model and basic spin exchange efficiency arguments. Underperformance was most notable in the smallest optical cells. We propose that all these systematic deviations from theory can be explained by invoking the presence of paramagnetic Rb clusters within the vapor. Cluster formation within saturated alkali vapors is well established and their interaction with resonant laser light was recently shown to create plasma-like conditions. Such cluster systems cause both Rb and 129Xe depolarization, as well as excess photon scattering. These effects were incorporated into the SEOP model by assuming that clusters are activated in proportion to excited-state Rb number density and by further estimating physically reasonable values for the nanocluster-induced, velocity-averaged spin-destruction cross-section for Rb (<σcluster-Rbv> ≈4×10-7 cm3s-1), 129Xe relaxation cross-section (<σcluster-Xev> ≈ 4×10-13 cm3s-1), and a non-wavelength-specific, photon-scattering cross-section (σcluster ≈ 1×10-12 cm2). The resulting modified SEOP model now closely matches experimental observations.

Exposing rodents to a combination of tobacco smoke and lipopolysaccharide results in an exaggerated inflammatory response in the lung

BACKGROUND AND PURPOSE

Acute exacerbations of chronic obstructive pulmonary disease (COPD), which are often associated with respiratory infections, are defined as a worsening of symptoms that require a change in medication. Exacerbations are characterized by a reduction in lung function, quality of life and are associated with increased pro-inflammatory mediators in the lung. Our aim was to develop an animal model to mimic aspects of this exaggerated inflammatory response by combining key etiological factors, tobacco smoke (TS) and bacterial lipopolysaccharide (LPS).

EXPERIMENTAL APPROACH

Rats were exposed to TS for 30 min twice a day for 2 days. On day 3 animals were exposed to LPS for 30 min followed by exposure to TS 5 h later. Inflammation, mucus and lung function were assessed 24 h after LPS.

KEY RESULTS

Neutrophils, mucus, oedema and cytotoxicity in lung and/or bronchoalveolar lavage was increased in animals exposed to combined LPS and TS, compared with either stimulus alone. Lung function was impaired in animals exposed to combined LPS and TS. Inflammatory cells, oedema and mucus were unaffected by pretreatment with the corticosteroid, budesonide, but were reduced by the phosphodiesterase 4 selective inhibitor roflumilast. Additionally, lung function was improved by roflumilast.

CONCLUSIONS AND IMPLICATIONS

We have established an in vivo model mimicking characteristic features of acute exacerbations of COPD including lung function decline and increased lung inflammation. This model may be useful to investigate molecular and cellular mechanisms underlying such exacerbations, to identify new targets and to discover novel therapeutic agents.

Heritability of features of the insulin resistance syndrome in a community-based study of healthy families

AIMS

To investigate genetic and environmental influences on anthropometric, metabolic and fibrinolytic traits of the insulin resistance syndrome (IRS) in a population not characterized by a high degree of insulin resistance.

METHODS

We recruited 537 adults from 89 randomly ascertained healthy families of white north European origin from the general population. We used maximum likelihood analysis to estimate the heritabilities and effects of environmental covariates on traits of the IRS in these families.

RESULTS

Adjusted for age, sex and body mass index, the traits showed considerable heritability. For waist-hip ratio, heritability was 15%. The heritabilities of fasting glucose, insulin and estimated insulin resistance were 20%, 23% and 23%, respectively. Heritabilities were 20%, 24% and 43% for triglycerides, LDL-cholesterol and HDL-cholesterol, respectively. For PAI-1 Ag and t-PA Ag they were 20% and 26%. Covariates explained 20-25% of the variance of lipids and insulin resistance and 35-36% of fibrinolytic factors. Childhood household influences significantly affected variance for waist-hip ratio (4%), fasting insulin (11%) and estimated insulin resistance (12%).

CONCLUSIONS

These family data demonstrate significant genetic influence on anthropometric, fibrinolytic and glucose-related traits of the IRS in a healthy white North European population.

Genetic contribution to circulating levels of hemostatic factors in healthy families with effects of known genetic polymorphisms on heritability

Levels of fibrinogen, factor VII (FVII), factor XIII (FXIII), plasminogen activator inhibitor (PAI)-1, and tissue plasminogen activator have been associated with coronary artery disease as have genetic polymorphisms. Quantitative genetic analyses allow determination of the genetic contribution to phenotypic variation. We investigated familial influences on these hemostatic factors in 537 adults from 89 randomly ascertained healthy families of white North European origin. We used maximum likelihood analysis to estimate the heritabilities of these factors and effects of covariates on the factors in these families. After adjustment for age and sex, the factors showed considerable heritability, varying from 26% (PAI-1) to 47% (FXIII complex). The influence of known polymorphisms was negligible for fibrinogen and contributed 2% to the variance of the FXIII complex and PAI-1 and 11% to the variance of FVII coagulant activity. Age, sex, body mass index, lifestyle, and metabolic covariates explained between 10% (FXIII) and 44% (PAI-1) of phenotypic variance. Childhood household influences significantly affected FVII (11%) and FXIII (18%). A significant degree of phenotypic variance of several hemostatic factors can be explained by additive genes and known covariates. The impact of certain well-characterized polymorphisms to the heritability is small in this population of healthy families, indicating the need to localize new genes influencing hemostatic factor levels.

Spectrum: the clinician and the "difficult" patient

Through the years, practitioners have attempted to discover more successful and empathic responses to address the needs of what has been referred to as the "difficult" patient. Writers in the past found it useful to define and cull out the distinctions that separated one type of "difficulty" in working with patients from another so as to "handle" some patients more effectively. Recently, it has been recognized and generally accepted that the "difficulty" in caring for patients frequently arises out of an interactional process between the patient and caregiver. This understanding requires practitioner self-awareness as well as reflection about motivations and responses to difficult clinical encounters. Two poems from the medical literature are explored as "clinical" examples that broaden our experience and understanding of the mystery and complexity of all human relationships.

Endoscopic techniques for rejuvenation of the midface

This article intends to give insight into the modern procedures available to facial plastic surgeons to accomplish aesthetic improvement of the midface. Emphasis is placed on repositioning of the malar pad and SOOF pad, which the author believes provides the greatest benefit to the patient.

Microdermabrasion

Particle-beam resurfacing is a tool that is useful in the management of epidermal abnormalities of the skin, including fine lines and wrinkles, actinic damage, clogged pores, comedonal acne, and mild acne scarring. For the procedure to be economically viable for the physician, it should be incorporated into a skin treatment program that can be managed safely and effectively by an appropriately trained nurse, aesthetician, or physician's assistant. This technique should be used to treat only the epidermis, because aluminum hydroxide crystals can be deposited into the dermis if the stratum basale is violated.

Aluminium deposition in liver and kidney following acute intravenous administration of aluminium chloride or citrate in conscious rats

1. Plasma, urinary, liver and kidney cell aluminium (Al) levels were monitored in the rat, 1h after intravenous administration of 29630 nmol (800 micrograms) Al as either Al chloride or as Al citrate (Al chloride plus excess sodium citrate). Al levels were measured in plasma, urine and liver by atomic absorption spectroscopy (AAS). Liver and kidney Al content was measured at the cellular and subcellular level by electron probe X-ray microanalysis (EPXMA). 2. Urinary excretion of Al was significantly higher (P < 0.01), when Al was given as the citrate than as the chloride. After 1h, plasma Al levels were significantly lower in the Al citrate group than the Al chloride group (59 +/- 3.7 vs 877 +/- 214 nmol ml-1, respectively; P < 0.01). 3. Al concentrations were significantly higher in the livers of rats receiving Al chloride (818 +/- 252 nmol g-1 wet weight; P < 0.05), than in either control or Al citrate groups (122 +/- 41 and 107 +/- 26 nmol g-1 wet weight, respectively). Al concentrations derived from EPXMA measurements were in agreement with AAS values for the three groups, with significantly higher Al concentrations in the Al chloride group (1.7 +/- 0.4 nmol mg-1 dry weight; P < 0.05) than in the control or Al citrate groups, where Al was not detectable. EPXMA analysis showed that Al was distributed in all liver organelles analysed (cytoplasm, mitochondria, nucleus, ER) and was not preferentially taken up by any one organelle in Al chloride treated rats. 4. Significant amounts of Al were found in cytoplasm and mitochondria of proximal tubule cells of rats given Al citrate (0.64 +/- 0.15 and 0.80 +/- 0.11 nmol mg-1 dry weight, respectively), but not in nuclei or lysosomes of these cells. Al levels were not detectable in control kidneys, in proximal tubule cells after Al chloride administration or distal tubule cells after either Al treatment.

Surgical therapy of the eyelids in patients with facial paralysis

Patients with facial paralysis have a degree of lagophthalmos and paralytic ectropion. We present our experience in the surgical management of 25 consecutive patients treated for these problems. Paralytic lagophthalmos was corrected using gold weights inserted into the upper eyelid. The advantages and disadvantages of this surgical technique are reviewed. Medial canthoplasty and lateral canthoplasty were performed to rectify paralytic ectropion. Ancillary procedures included browpexy, upper-lid blepharoplasty, and temporalis sling. The results were excellent in 23 of 25 patients and good in the remaining two. After a minimum of 6 months' follow-up, there were no complications. The authors believe that the above procedures will yield consistently excellent cosmetic and functional results in patients with paralysis of the eyelids.

Incision planning and basic soft-tissue surgery

Incisions in the head and neck region need not result in unsightly scars. For open incisions, use of the RSTL or skin creases, along with good soft-tissue technique and attention to detail on closure, will yield excellent cosmetic results.

Analysis of patient response to preoperative computerized video imaging

Preoperative computer-assisted video imaging was performed on 50 consecutive rhinoplasty candidates, along with routine preoperative photographs and assessment. Each patient then completed a questionnaire dealing with the imaging process. Patient acceptance of the imaging process was excellent. Responses indicated that most patients felt that video imaging improved communication between patient and surgeon, increased patient confidence in surgery and surgeon, and enhanced the patient-physician relationship. The future use of computer-assisted video imaging in teaching, preoperative planning, and improved post-operative patient satisfaction is discussed.

Clavicular division technique. A new approach for lengthening the pectoralis flap

Complications associated with using the pectoralis major myocutaneous flap increase significantly when a portion of the paddle is randomized and/or the flap is closed under tension. The clavicular division technique was devised to increase the length of the flap to help alleviate this problem. Thirty pectoralis major muscle flaps were dissected in fresh cadavers, using the clavicular division technique. The length of the flap after transposition was measured and recorded before and after clavicular division. The distance from the sternal notch to the clavicular division point was also recorded. The average gain in length was found to be 2.9 cm, with a range of 0.5 cm to 6.5 cm. The clavicular division technique has been used since in five patients. The increase in length has allowed us to discard some or all of the random portion of the flap. We advocate the use of this procedure on any patient where the surgeon is concerned about the viability of the random portion of the flap and/or when it is felt that the tension on the suture line is excessive.

Giant acquired tracheoesophageal fistulas: strategy for successful management

Giant tracheoesophageal fistulas (TEF) present a significant management problem for the head and neck surgeon. Chronic aspiration and sepsis are associated complications that occur in these patients, who are frequently already debilitated from pre-existing medical calamities. The combination results in prolonged morbidity and frequent mortality. Recently, we have managed two patients with this difficult problem. The first patient was managed using conventional methods well described in the literature with an unsuccessful outcome. The second was managed differently using a two-stage approach. The esophageal stream was first excluded from the respiratory system via a surgical approach, which to the best of our knowledge has not been previously described in the literature. After a period of convalescence, the patient's alimentary tract is reconstituted with a gastric pull-up, reversed gastric tube, or colon interposition. We propose this as an alternative method of management for TEF.