Laboratory evidence of Weibel magnetogenesis driven by temperature gradient using three-dimensional synchronous proton radiography.

The origin of the cosmic magnetic field remains an unsolved mystery, relying not only on specific dynamo processes but also on the seed field to be amplified. Recently, the diffuse radio emission and Faraday rotation observations reveal that there has been a microgauss-level magnetic field in intracluster medium in the early universe, which places strong constraints on the strength of the initial field and implies the underlying kinetic effects; the commonly believed Biermann battery can only provide extremely weak seed of 10-21 G. Here, we present evidence for the spontaneous Weibel-type magnetogenesis in laser-produced weakly collisional plasma with the three-dimensional synchronous proton radiography, where the distribution anisotropy directly arises from the temperature gradient, even without the commonly considered interpenetrating plasmas or shear flows. This field can achieve sufficient strength and is sensitive to Coulomb collision. Our results demonstrate the importance of kinetics in magnetogenesis in weakly collisional astrophysical scenarios.

Reduction of Backward Scatterings at the Low-Coherence Kunwu Laser Facility.

We report the first experimental observation on the reduction of backward scatterings by an instantaneous broadband laser with 0.6% bandwidth in conditions of interest for inertial confinement fusion at the low-coherence Kunwu laser facility. The backscatter of stimulated Brillouin scattering (SBS) was robustly reduced by half at intensities of 1-5×10^{14} W/cm^{2} with the 0.53-µm broadband laser in comparison with the monochromatic laser. As SBS dominates energy loss of laser-plasma interactions, the reduction of that demonstrates the enhancement of laser-target coupling by the use of broadband laser. The mitigation of filamentation leads to the reduction of stimulated Raman backscattering at low intensities. In addition, the three-halves harmonic emission was reduced with the broadband laser as well.

An exploratory investigation into the influence of risk factors on driver injury severity in angle crashes: A random parameter bivariate ordered probit model approach.

OBJECTIVE: Angle crashes have been acknowledged as a concerning issue in the traffic safety field, though there is limited understanding of the contributions of risk factors to injury severity. This article aims to examine the impact of risk factors and unobserved heterogeneity on the severity of driver injuries in angle collisions by utilizing angle crash data in the United States from 2016 to 2021. METHODS: The relationship between risk factors and driver injury severities in angle crashes was investigated using a random parameter bivariate ordered probit model (RPBOP) with 4 categories of injury severity classified as outcome variables, including no injury, possible injury, minor injury, and serious jury. Risk factors were considered as explanatory variables, classified as driver characteristics, vehicle characteristics, road characteristics, environmental characteristics, time characteristics, and crash characteristics. Bayesian inference was used to assess the unobserved heterogeneity in risk factors, and marginal effects were computed to analyze the effect of each factor on injury outcomes. RESULTS: The findings demonstrate that risk factors have varying effects on driver involvement in angle crashes. Certain factors exhibited unobserved heterogeneity, including young drivers (ages 25-44), older drivers (over age 59), road grade, and collision point orientation. On the other hand, other factors, such as female gender, motorcycles, intersections, speed limit (>50 mph), poor lighting conditions, adverse weather, urban areas, and workdays, were shown to significantly increase the likelihood of driver injury in angle collisions, as well as increase susceptibility to fatal injury. CONCLUSIONS: This article offers new insights into reducing driver injuries in angle crashes and has the potential to inform policy development aimed at preventing such incidents. Further research could utilize multisource data fusion and investigate the spatiotemporal stability of risk factors to enhance the generalizability of angle collision prevention strategies.

Double-spherically bent crystal scheme of stigmatic x ray monochromatic backlit imaging.

We propose an aberration-free monochromatic x ray backlit imaging scheme using a combination of convex and concave spherically bent crystals. This configuration works with a wide range of Bragg angles, satisfying the conditions for stigmatic imaging at a particular wavelength. However, the assembly accuracy of the crystals must meet the Bragg relation criteria for spatial resolution to increase the detection efficiency. Here, we develop a collimator prism with a cross reference line engraved on a plane mirror to adjust a matched pair of Bragg angles as well as the intervals between the two crystals and the object to be coupled with the detector. We explore the realization of monochromatic backlighting imaging with a concave Si-533 crystal and a convex α-Quartz-2023 crystal, obtaining a spatial resolution of approximately 7 µm and a field of view of at least 200 µm. To the best of our knowledge, this is the best spatial resolution of monochromatic images of a double-spherically bent crystal to date. Our experimental results are presented to demonstrate the feasibility of this imaging scheme with x rays.

Laboratory Study on Disconnection Events in Comets.

When comets interacting with solar wind, straight and narrow plasma tails will be often formed. The most remarkable phenomenon of the plasma tails is the disconnection event, in which a plasma tail is uprooted from the comet's head and moves away from the comet. In this paper, the interaction process between a comet and solar wind is simulated by using a laser-driven plasma cloud to hit a cylinder obstacle. A disconnected plasma tail is observed behind the obstacle by optical shadowgraphy and interferometry. Our particle-in-cell simulations show that the difference in thermal velocity between ions and electrons induces an electrostatic field behind the obstacle. This field can lead to the convergence of ions to the central region, resulting in a disconnected plasma tail. This electrostatic-field-induced model may be a possible explanation for the disconnection events of cometary tails.

Eight-channel Kirkpatrick-Baez microscope for multiframe x-ray imaging diagnostics in laser plasma experiments.

Because grazing-incidence Kirkpatrick-Baez (KB) microscopes have better resolution and collection efficiency than pinhole cameras, they have been widely used for x-ray imaging diagnostics of laser inertial confinement fusion. The assembly and adjustment of a multichannel KB microscope must meet stringent requirements for image resolution and reproducible alignment. In the present study, an eight-channel KB microscope was developed for diagnostics by imaging self-emission x-rays with a framing camera at the Shenguang-II Update (SGII-Update) laser facility. A consistent object field of view is ensured in the eight channels using an assembly method based on conical reference cones, which also allow the intervals between the eight images to be tuned to couple with the microstrips of the x-ray framing camera. The eight-channel KB microscope was adjusted via real-time x-ray imaging experiments in the laboratory. This paper describes the details of the eight-channel KB microscope, its optical and multilayer design, the assembly and alignment methods, and results of imaging in the laboratory and at the SGII-Update.

Laparoscopy-Assisted D2 Radical Gastrectomy for Advanced Gastric Cancer.

BACKGROUND/AIMS: The aim of this study was to investigate the efficacy and advantages of laparoscopy-assisted gastrectomy (LAG) with D2 lymphadenectomy versus conventional open D2 gastrectomy (ODG) in advanced gastric cancer (AGC) patients. METHODOLOGY: From June 2009 to June 2014, 233 patients who were treated by conventional radical ODG and 188 cases who underwent radical LAG for AGC at our department were enrolled in this study. Clinical data recorded in hospital database was retrospectively reviewed and analyzed. RESULTS: There were no significant differences in age, gender or preoperative laboratory tests distribution between the LAG group and the ODG group. Two (1%) of the patients who underwent LAG required conversion to ODG. The advantages of minimally invasive surgery including earlier recovery of bowel movements and shorter postoperative hospitalization time were observed in LAG group. The number of harvested lymph nodes was 24.3 ± 3.3 in the LAG group and 25.0 ± 2.8 in ODG (p = 0.110). CONCLUSIONS: Although prospective randomized trials with long follow-up period are needed to identify the feasibility, we have shown the safety and advantages of LAG with D2 lymphadenectomy for treating AGC patients in this study.

Sentinel lymph node and skip metastases in gastric cancer: a prospective study.

BACKGROUND/AIMS: The aim of the present study was to investigate localization and distribution of sentinel lymph node (SLN) in gastric cancer and influenced factors of skip metastasis. METHODOLOGY: Eighty-nine cases with solitary or single station metastatic lymph nodes (LNs) among 779 gastric cancer patients were included in this study. D2 or D2+ lymph node dissection with total or distal gastrectomy had been performed. The location of SLNs and characteristics were analyzed retrospectively. RESULTS: Seventy-one patients (79.8%) had SLNs at the first level of the regional LN group and 18 cases (20.2%) had skip metastases SLNs. NO.7 (44.4%) and NO.8a (27.8%) were the most common sites of skip metastases. Multivariate analysis identified the differentiated degree of tumor as the only significant influenced factor of skip metastases (p=0.031). The number of metastatic SLNS was significantly greater in advanced gastric cancer patients (2.4 ± 1.4) than early gastric cancer patients (1.5 ± 0.9) (pT4 vs. pT1, p=0.002; pT4 vs. pT2, p=0.014; pT3 vs. pT1, p=0.018). CONCLUSIONS: The differentiated degree of gastric cancer is the most important influenced factor of skip metastases and NO.7 and NO.8a are the most important N2 LN stations that should be observed when lymphadenectomy is performed.