Search

Abstract High-intensity, short-pulse lasers are crucial for generating energetic electrons that produce high-energy-density (HED) states in matter, offering potential applications in igniting dense fusion fuels for fast ignition laser fusion. High-density targets heated by these electrons exhibit spatially non-uniform and highly transient conditions, which have been challenging to characterize due to limitations in diagnostics that provide simultaneous high spatial and temporal resolution. Here, we employ an X-ray Free Electron Laser (XFEL) to achieve spatiotemporally resolved measurements at sub-micron and femtosecond scales on a solid-density copper foil heated by laser-driven fast electrons. Our X-ray transmission imaging reveals the formation of a solid-density hot plasma localized to the laser spot size, surrounded by Fermi degenerate, warm dense matter within a picosecond, and the energy relaxation occurring within the hot plasma over tens of picoseconds. These results validate 2D particle-in-cell simulations incorporating atomic processes and provide insights into the energy transfer mechanisms beyond current simulation capabilities. This work significantly advances our understanding of rapid fast electron heating and energy relaxation in solid-density matter, serving as a key stepping stone towards efficient high-density plasma heating and furthering the fields of HED science and inertial fusion energy research using intense, short-pulse lasers.

Currently, software systems must be appropriately developed to support an amount of variability for accommodating different requirements. To support such development, a diversity of tools has already been designed for variability management (i.e., identification, modeling, evaluation, and realization). However, due to this diversity, there is a lack of consensus on what in fact software variability tools are and even what functionalities they should provide. Besides that, the building of new tools is still an effort- and time-consuming task. To support their building, we present VMTools-RA, a reference architecture that encompasses knowledge and practice for developing and evolving variability tools. Designed in a systematic way, VMTools-RA was evaluated throughout: a controlled experiment with software developer practitioners; and an instantiation of the VMTools-RA architecture to implement a software variability tool, named SMartyModeling. As a result, VMTools-RA is evidenced to be feasible and it can be considered an important contribution to the software variability and developers of variability-intensive software systems community, which require specific tools developed in a faster manner with less risk, what a reference architecture could provide.

High performance liquid chromatography methods were established for separation of alkenylacyl, alkylacyl, and diacyl acetylglycerols derived from ethanolamine glycerophospholipids (EGP) and for separation of the individual molecular species from each of the separated classes. The EGP were isolated from bovine brain, hydrolyzed with phospholipase C, and acetylated with acetic anhydride. The three classes of diradylacetylglycerols were separated quantitatively on a mu Porasil silica column. Individual classes were further fractionated on a Zorbax ODS reverse phase column. By gas--liquid chromatographic quantitation of each peak, 29-33 different molecular species were identified within each class. For alkenylacyl-GPE, the major species were 18:1-18:1, 21.8%, and 16:0-18:1, 14.8%. Polyenoic fatty acids predominated at the 2-position of diacyl-GPE. The major species were 18:0-22:6 (n-3), 25.5%, and 18:0-20:4 (n-6), 15.8%. Three species of alkylacyl-GPE, 18:0-20:6 (n-3), 16:0-22:4 (n-6), and 18:0-22:4 (n-6), each accounted for 10%.

The ethanolamine glycerophospholipids (EGP) contain most of the arachidonate (20:4, n-6) and adrenate (22:4, n-6), potential precursors of biologically potent prostaglandins and related compounds. Much better methods utilizing high performance liquid chromatography (HPLC) techniques are now available for the study of the molecular species of all three classes, namely diacyl, alkenylacyl (plasmalogen), and alkylacyl. Different molecular species may have different functions. This possibility was studied by examining the rates of incorporation of [3H]arachidonic acid into the three major molecular species of each of the three classes of ethanolamine glycerophospholipids. After the intracerebral injection of [3H]20:4 into rat brain, it was rapidly converted to 22:4(n-6). Of the total radioactivity, 10-20% was located in 22:4 in alkenylacyl and diacyl-GPE. In the alkylacyl-GPE, labeled 22:4 was preferentially incorporated and accounted for 50-60% of the total radioactivity. The primary arachidonoyl molecular species of alkenylacyl, alkylacyl, and diacyl-GPE were the 18:1-20:4, 16:0-20:4, and 18:0-20:4 species. The alkylacyl class contained almost equal proportions of these three molecular species. On the other hand, the 20:4 in alkenylacyl and diacyl classes was combined largely with 18:0 groups at the sn-1 position. In particular, the 18:0-20:4 species comprised about 80% of arachidonoyl molecular species of the diacyl class. In all three classes, the highest specific radioactivities were found in the 18:1-20:4 species, whereas the 18:0-20:4 species had the lowest specific radioactivity. Over the period 60 min-24 hr, the diacyl 18:0-20:4 and all three arachidonoyl molecular species of the alkenylacyl class increased in specific radioactivity more rapidly than the other arachidonoyl molecular species.

Full-aperture ion optics simulations have been conducted for the inhomogeneous plasma source of a miniature ion propulsion system (MIPS) to design a high-efficiency accelerator grid that provides high degree of the neutral confinement and absence of direct ion impingement. The designed accelerator grid has flat upstream and smoothly curved downstream surfaces with straight holes for easy low-cost manufacture. The diameter of the accelerator aperture was changed from the nominal value of 0.40 mm to 0.25 mm, which decreased neutral leakage and increased the propellant utilization efficiency from 31 to 50%. The direct impingement of ions caused by decreasing the accelerator aperture diameter was compensated by reducing the thickness of the accelerator grid while taking into account the inhomogeneous ion beam current density profile of the MIPS. An off-design performance simulation was conducted to validate the proposed grid design; the obtained results showed that the ion beam could be accelerated smoothly even during throttling the beam current between 75 and 150%. A grid wear simulation was also performed to compare the changes in the propellant utilization efficiency between the nominal and high-efficiency grids caused by erosion. It was found that the propellant utilization efficiency of the high-efficiency grid was greater than that of the nominal grid within the first 5,000 h of operation and that its lifetime exceeded 10,000 h of the accumulated operation time. By using the proposed high-efficiency accelerator grid and MIPS plasma source, the propellant utilization efficiency was increased, while the accelerator impingement current became negligible.

A significant enhancement of radiation doses is expected for aircrews during ground-level enhancement (GLE) events, while the possible radiation hazard remains an open question during non-GLE solar energetic particle (SEP) events. Using a new air-shower simulation driven by the proton flux data obtained from GOES satellites, we show the possibility of significant enhancement of the effective dose rate of up to 4.5 μSv h−1 at a conventional flight altitude of 12 km during the largest SEP event that did not cause a GLE. As a result, a new GOES-driven model is proposed to give an estimate of the contribution from the isotropic component of the radiation dose in the stratosphere during non-GLE SEP events.

The gang of four design patterns are widely adopted in industry as best practices and their effect on software quality has been long investigated in academia, with both positive and negative consequences being observed. One important parameter that relates to the effect of patterns on quality is the deterioration of pattern instances due to the buildup of artifacts unrelated to the pattern structure. This is called pattern grime and can potentially diminish some of the benefits of using patterns in the first place. In this paper we investigate the relation between pattern grime and three qualities, namely performance, security, and correctness. To this end, we conducted a case study with five industrial projects (approx. 260 000 lines of code) implemented by 16 developers. Our findings suggest a correlation between the accumulation of grime and decreased levels of performance, security, and correctness. Moreover, factors such as the project itself, pattern type and the developer can influence this relation. The obtained results can benefit both researchers and practitioners, as we provide evidence on the accumulation of pattern grime and its correlation to performance, security and correctness, and how different factors affect these correlations.

We administered various memory tests and neuroimaging examinations to four pure cases who met Hodges' clinical criteria for transient global amnesia (TGA), during and after the attack. The purpose of the present study was to determine whether procedural learning is acquired during TGA and whether priming effects are preserved during TGA, and to investigate the anatomical basis of various memory subcomponents through these cases. Episodic memory was severely disturbed only during TGA, consistent with previous studies. Procedural learning during TGA examined by a drawing skill test and a reading skill test developed by us, and the Tower of Toronto, was preserved during TGA, consistent with one earlier report dealing with procedural memory during TGA. Priming effects during TGA have never been assessed. A word completion priming task with Kanji letters developed by us demonstrated that priming effects were preserved during TGA. Neuroradiologically, single photon emission computed tomograph hippocampal images clearly revealed a hypoperfusion confined to the medial portion of the bilateral temporal lobe only during the attack. These findings indicate that the medial portion of the temporal lobe is important for episodic memory as described in previous reports, but did not play an important role in procedural memory and priming effects.

We investigated completion phenomenon for proverbs in cases demonstrating transcortical sensory aphasia due to a variety of diseases. Lack of this completion was exclusively observed in patients with focal atrophy. These patients showed a selective and consistent impairment in word comprehension without phonemic cue effects in naming. The completion phenomenon was present in patients demonstrating transcortical sensory aphasia due to other cerebral diseases. In these patients, comprehension deficits were not selective for words, or words not comprehended were inconsistent and some phonemic cue effects were observed. In a previous study, we reported that completion phenomena for multiplication tables, serial numbers and names of days were frequently noted in patients with focal atrophy. Together with the present findings, these results suggest that lack of proverb completion may be attributed to a selective, systematic and complete loss of the meaning representations for language units such as words and proverbs. In addition, pathological processes of focal atrophy with temporal predominance might selectively affect the semantic memory for language as a unit.