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.

Management of Undifferentiated Solitary Mucinous Cystic Lesion of the Pancreas: A Clinical Dilemma

BACKGROUND

Management of solitary mucinous cystic lesions of the pancreas (MCLs) relies on correct differentiation between branch duct intraductal papillary mucinous neoplasm (BD-IPMN) and mucinous cystic neoplasm (MCN). Current international consensus guidelines recommend resection for MCN, and unifocal BD-IPMN can be followed in the absence of worrisome features/high-risk stigmata. We hypothesized that preoperative differentiation of solitary MCLs is suboptimal, and that all solitary MCLs should be treated similarly.

STUDY DESIGN

A retrospective review of an institutional database (2003 to 2016) identified 711 patients who underwent resection for pancreatic cyst. Only lesions that met cytologic or biochemical criteria for diagnosis of MCLs were included. Mucinous cystic neoplasms were defined by presence of ovarian stroma on pathology. Patients with formal preoperative diagnosis of BD-IPMN (multifocality, GNAS mutation) were excluded.

RESULTS

One hundred and eighty solitary MCLs were identified on preoperative imaging (mean age 54 years, 24% men). On surgical pathology, 108 were MCNs and 72 BD-IPMNs. There was no difference in invasive rate (7 of 108 [6.5%] MCNs vs 4 of 72 [5.6%] BD-IPMN; p ≈ 1). Pancreatic ductal connectivity was reported on imaging/endoscopy in 10 of 108 (9%) MCNs and 22 of 72 (31%) BD-IPMNs, representing 67% accuracy in differentiating MCNs from BD-IPMNs. On multivariate analysis, typical risk factors failed to predict invasiveness in either MCNs or BD-IPMNs. When all undifferentiated solitary MCLs were analyzed together, older age (p = 0.03) and cyst size (p = 0.04) were associated with increased invasive rate in multivariate analysis.

CONCLUSIONS

Unreliable differentiation and limited ability to predict invasiveness make solitary MCLs clinically challenging. With similar invasive rates, MCN and unifocal BD-IPMNs should be merged into one new entity for management, the undifferentiated solitary MCL.

Combined effects of angiostatin and ionizing radiation in antitumour therapy

Angiogenesis, the formation of new capillaries from pre-existing vessels, is essential for tumour progression. Angiostatin, a proteolytic fragment of plasminogen that was first isolated from the serum and urine of tumour-bearing mice, inhibits angiogenesis and thereby growth of primary and metastatic tumours. Radiotherapy is important in the treatment of many human cancers, but is often unsuccessful because of tumour cell radiation resistance. Here we combine radiation with angiostatin to target tumour vasculature that is genetically stable and therefore less likely to develop resistance. The results show an antitumour interaction between ionizing radiation and angiostatin for four distinct tumour types, at doses of radiation that are used in radiotherapy. The combination produced no increase in toxicity towards normal tissue. In vitro studies show that radiation and angiostatin have combined cytotoxic effects on endothelial cells, but not tumour cells. In vivo studies show that these agents, in combination, target the tumour vasculature. Our results provide support for combining ionizing radiation with angiostatin to improve tumour eradication without increasing deleterious effects.