Ultra-high-pressure generation in the relativistic transparency regime in laser-irradiated nanowire arrays.

We show that an ultra-high-pressure plasma can be generated when an aligned nanowire is irradiated by a laser with relativistic transparent intensity. Using a particle-in-cell simulation, we demonstrate that the expanded plasma following the z pinch becomes relativistically transparent and compressed longitudinally by the oscillating component of the ponderomotive force. The compressed structure persists throughout the pulse duration with a maximum pressure of 40Tbar when irradiated with a laser at an intensity of 10^{23}Wcm^{-2}, 5× higher than the z-pinch pressure. These results suggest an alternative approach to extending the current attainable pressure in the laboratory.

Luminous, relativistic, directional electron bunches from an intense laser driven grating plasma.

Bright, energetic, and directional electron bunches are generated through efficient energy transfer of relativistic intense (~ 1019 W/cm2), 30 femtosecond, 800 nm high contrast laser pulses to grating targets (500 lines/mm and 1000 lines/mm), under surface plasmon resonance (SPR) conditions. Bi-directional relativistic electron bunches (at 40° and 150°) are observed exiting from the 500 lines/mm grating target at the SPR conditions. The surface plasmon excited grating target enhances the electron flux and temperature by factor of 6.0 and 3.6, respectively, compared to that of the plane substrate. Particle-in-Cell simulations indicate that fast electrons are emitted in different directions at different stages of the laser interaction, which are related to the resultant surface magnetic field evolution. This study suggests that the SPR mechanism can be used to generate multiple, bright, ultrafast relativistic electron bunches for a variety of applications.

Enhancement of laser-focused intensity greater than 10 times through a re-entrant cone in the petawatt regime.

A versatile method to enhance the laser pulse intensity by one order of magnitude from 8×1020W/cm2 using a single plastic micro-cone target is proposed in this Letter. We found an increase of the initial laser pulse intensity by more than 10 times for a micro-cone tip diameter of 5 µm upon performing two-dimensional particle-in-cell simulations. Numerical simulations of the spatio-temporal electromagnetic field distribution are used to replicate similar dependence of the maximum laser intensity to the cone tip diameter.

Direct observation of imploded core heating via fast electrons with super-penetration scheme.

Fast ignition (FI) is a promising approach for high-energy-gain inertial confinement fusion in the laboratory. To achieve ignition, the energy of a short-pulse laser is required to be delivered efficiently to the pre-compressed fuel core via a high-energy electron beam. Therefore, understanding the transport and energy deposition of this electron beam inside the pre-compressed core is the key for FI. Here we report on the direct observation of the electron beam transport and deposition in a compressed core through the stimulated Cu Kα emission in the super-penetration scheme. Simulations reproducing the experimental measurements indicate that, at the time of peak compression, about 1% of the short-pulse energy is coupled to a relatively low-density core with a radius of 70 µm. Analysis with the support of 2D particle-in-cell simulations uncovers the key factors improving this coupling efficiency. Our findings are of critical importance for optimizing FI experiments in a super-penetration scheme.

A ten-inch manipulator (TIM) based fast-electron spectrometer with multiple viewing angles (OU-ESM).

The measurement of angularly resolved energy distributions of mega-electron-volt electrons is important for gaining a better understanding of the interaction of ultra-intense laser pulses with plasma, especially for fast-ignition laser-fusion research. It is also crucial when evaluating the production of suprathermal (several 10-keV) electrons through laser-plasma instabilities in conventional hot-spot-ignition and shock-ignition research. For these purposes, we developed a 10-in. manipulator-based multichannel electron spectrometer-the Osaka University electron spectrometer (OU-ESM)-that combines angular resolution with high-energy resolution. The OU-ESM consists of five small electron spectrometers set at every 5°, with an energy range from ∼40 keV to ∼40 MeV. A low-magnetic-field option provides a higher spectral resolution for an energy range of up to ∼5 MeV. We successfully obtained angularly resolved electron spectra for various experiments on the OMEGA and OMEGA EP laser systems.

Elevated fibrinogen, von Willebrand factor, and Factor VIII confer resistance to dilutional coagulopathy and activated protein C in normal pregnant women.

BACKGROUND: Gestational changes in coagulation factor concentrations include elevations in fibrinogen, Factor VIII, and von Willebrand factor (vWF). We hypothesised that blood samples from term pregnant (TP) subjects are less prone to coagulation disturbances from haemodilution compared with those from non-pregnant (NP) females. METHODS: Blood samples were collected from 15 NP and 15 TP subjects. In vitro haemodilution with normal saline was assessed by modified Clauss fibrinogen assay, factor activity, flow-chamber assay, and thromboelastometry. The impact of human fibrinogen concentrate (hFC), cryoprecipitate, and vWF/Factor VIII (FVIII) concentrate replacement in diluted TP and NP blood was compared. Thrombin generation and activated protein C sensitivity were assessed. RESULTS: TP blood contained twice the concentrations of fibrinogen, FVIII, and vWF relative to NP blood (P<0.0001). Platelet thrombus formation (PTF) under flow was reduced by 99.2% and 69.2% in diluted NP and TP blood, respectively. Platelet thrombus formation was partially restored by adding vWF/FVIII, but not hFC or cryoprecipitate. Fibrin clot firmness approached the threshold of 10 mm in diluted NP blood, and clot firmness was effectively restored by hFC, but not by vWF/FVIII. In the presence of thrombomodulin, peak thrombin generation was decreased by 86.7% in NP plasma, but by 31.8% in TP plasma (P<0.0001 vs NP plasma), indicating reduced activated protein C sensitivity in TP plasma. Both elevated FVIII and haemodilution contributed to activated protein C insensitivity. CONCLUSIONS: Our in vitro model showed relative resistance of TP blood to dilutional coagulation changes with respect to platelet adhesion, fibrin polymerisation, and thrombin generation. Careful therapeutic monitoring for different pro-haemostatic agents in pregnant women is warranted.

Advanced high resolution x-ray diagnostic for HEDP experiments.

High resolution X-ray imaging is crucial for many high energy density physics (HEDP) experiments. Recently developed techniques to improve resolution have, however, come at the cost of a decreased field of view. In this paper, an innovative experimental detector for X-ray imaging in the context of HEDP experiments with high spatial resolution, as well as a large field of view, is presented. The platform is based on coupling an X-ray backligther source with a Lithium Fluoride detector, characterized by its large dynamic range. A spatial resolution of 2 µm over a field of view greater than 2 mm2 is reported. The platform was benchmarked with both an X-ray free electron laser (XFEL) and an X-ray source produced by a short pulse laser. First, using a non-coherent short pulse laser-produced backlighter, reduced penumbra blurring, as a result of the large size of the X-ray source, is shown. Secondly, we demonstrate phase contrast imaging with a fully coherent monochromatic XFEL beam. Modeling of the absorption and phase contrast transmission of X-ray radiation passing through various targets is presented.

Factor IX from prothrombin complex concentrate augments low dose tissue factor-triggered thrombin generation in vitro.

BACKGROUND: Prothrombin complex concentrate (PCC) is increasingly used to correct acquired coagulopathy in trauma and surgery. Dosing of PCC is guided by the prothrombin time, which only reflects the onset of thrombin generation, but does not account for variations in intrinsic pathway coagulation factors, including factor IX (FIX). We hypothesised that FIX contained in PCC could strongly influence thrombin generation patterns. METHODS: Pooled normal, FIX-deficient, and warfarinised plasma were used to analyse the effects of FIX contained in PCC. PCC was evaluated at final concentrations of 0.2 and 0.4 IU ml-1 in FIX-deficient and normal plasma, and at 0.6 IU ml-1 in warfarinised plasma with elevated FVIII (1.5 IU ml-1), 40% dilution with saline, or both. The effects on thrombin generation were assessed by measuring both procoagulant and inhibitory segments. RESULTS: FIX-deficient plasma had lower peak thrombin generation [30.6 (20.5-35.8) nM vs 130.2 (107-168) nM] and endogenous thrombin potential [472 (391-532) nM vs 1096 (958-1190) nM] than normal plasma. PCC addition resulted in significant increases of peak thrombin generation [81.8 (37.3-98.3) nM] and endogenous thrombin potential [808 (472-842) nM] in FIX-deficient plasma. The combination of FVIII and PCC resulted in greater increases relative to each agent alone, restoring normal thrombin generation. After 40% dilution, adding PCC, FVIII, or both, to FIX-deficient plasma increased peak thrombin generation, and prolonged the inhibitory phase of the endogenous thrombin potential. CONCLUSIONS: FIX derived from PCC strongly enhances tissue factor-triggered thrombin generation in the presence of elevated FVIII activity. Haemodilution further enhances procoagulant effects of FIX and FVIII by slowing down inhibition of procoagulant enzymes. Dosing of PCC per prothrombin time may underestimate PCC's procoagulant potential because it does not account for intrinsic tenase or antithrombin activity.

The extreme light infrastructure-nuclear physics (ELI-NP) facility: new horizons in physics with 10 PW ultra-intense lasers and 20 MeV brilliant gamma beams.

The European Strategy Forum on Research Infrastructures (ESFRI) has selected in 2006 a proposal based on ultra-intense laser fields with intensities reaching up to 1022-1023 W cm-2 called 'ELI' for Extreme Light Infrastructure. The construction of a large-scale laser-centred, distributed pan-European research infrastructure, involving beyond the state-of-the-art ultra-short and ultra-intense laser technologies, received the approval for funding in 2011-2012. The three pillars of the ELI facility are being built in Czech Republic, Hungary and Romania. The Romanian pillar is ELI-Nuclear Physics (ELI-NP). The new facility is intended to serve a broad national, European and International science community. Its mission covers scientific research at the frontier of knowledge involving two domains. The first one is laser-driven experiments related to nuclear physics, strong-field quantum electrodynamics and associated vacuum effects. The second is based on a Compton backscattering high-brilliance and intense low-energy gamma beam (<20 MeV), a marriage of laser and accelerator technology which will allow us to investigate nuclear structure and reactions as well as nuclear astrophysics with unprecedented resolution and accuracy. In addition to fundamental themes, a large number of applications with significant societal impact are being developed. The ELI-NP research centre will be located in Magurele near Bucharest, Romania. The project is implemented by 'Horia Hulubei' National Institute for Physics and Nuclear Engineering (IFIN-HH). The project started in January 2013 and the new facility will be fully operational by the end of 2019. After a short introduction to multi-PW lasers and multi-MeV brilliant gamma beam scientific and technical description of the future ELI-NP facility as well as the present status of its implementation of ELI-NP, will be presented. The science and examples of societal applications at reach with these electromagnetic probes with much improved performances provided at this new facility will be discussed with a special focus on day-one experiments and associated novel instrumentation.

Channel optimization of high-intensity laser beams in millimeter-scale plasmas.

Channeling experiments were performed at the OMEGA EP facility using relativistic intensity (>10^{18}W/cm^{2}) kilojoule laser pulses through large density scale length (∼390-570 µm) laser-produced plasmas, demonstrating the effects of the pulse's focal location and intensity as well as the plasma's temperature on the resulting channel formation. The results show deeper channeling when focused into hot plasmas and at lower densities, as expected. However, contrary to previous large-scale particle-in-cell studies, the results also indicate deeper penetration by short (10 ps), intense pulses compared to their longer-duration equivalents. This new observation has many implications for future laser-plasma research in the relativistic regime.

Perioperative management of rare coagulation factor deficiency states in cardiac surgery.

Rare bleeding disorders (RBDs) include the hereditary deficiency of fibrinogen, factor (F)II, FV, FV + FVIII, FVII, FX, FXI or FXIII. RBDs do not confer a protective effect against atheromatous plaque formation, and thus the need for cardiovascular (CV) surgery in RBD patients is expected to increase with improved healthcare access (diagnosis and management) and longevity of the population. Clinical data regarding the management of RBDs in this setting are sparse, but the perioperative care team is obliged to gain a better understanding on available biological and pharmacological hemostatic agents. Perioperative management of RBDs in CV surgery is further complicated by heparin anticoagulation, haemodilution, and consumption of procoagulant and anticoagulant proteins associated with cardiopulmonary bypass (CPB). The aims of this review are to summarize pathophysiology of RBDs and laboratory monitoring pertinent to CV surgery, available factor replacement agents, and to provide the framework for perioperative coagulation management of RBD patients.

Coherent X-ray beam metrology using 2D high-resolution Fresnel-diffraction analysis.

Direct metrology of coherent short-wavelength beamlines is important for obtaining operational beam characteristics at the experimental site. However, since beam-time limitation imposes fast metrology procedures, a multi-parametric metrology from as low as a single shot is desirable. Here a two-dimensional (2D) procedure based on high-resolution Fresnel diffraction analysis is discussed and applied, which allowed an efficient and detailed beamline characterization at the SACLA XFEL. So far, the potential of Fresnel diffraction for beamline metrology has not been fully exploited because its high-frequency fringes could be only partly resolved with ordinary pixel-limited detectors. Using the high-spatial-frequency imaging capability of an irradiated LiF crystal, 2D information of the coherence degree, beam divergence and beam quality factor M2 were retrieved from simple diffraction patterns. The developed beam metrology was validated with a laboratory reference laser, and then successfully applied at a beamline facility, in agreement with the source specifications.

Density and temperature characterization of long-scale length, near-critical density controlled plasma produced from ultra-low density plastic foam.

The ability to produce long-scale length (i.e. millimeter scale-length), homogeneous plasmas is of interest in studying a wide range of fundamental plasma processes. We present here a validated experimental platform to create and diagnose uniform plasmas with a density close or above the critical density. The target consists of a polyimide tube filled with an ultra low-density plastic foam where it was heated by x-rays, produced by a long pulse laser irradiating a copper foil placed at one end of the tube. The density and temperature of the ionized foam was retrieved by using x-ray radiography and proton radiography was used to verify the uniformity of the plasma. Plasma temperatures of 5-10 eV and densities around 10(21) cm(-3) are measured. This well-characterized platform of uniform density and temperature plasma is of interest for experiments using large-scale laser platforms conducting High Energy Density Physics investigations.

Slowdown mechanisms of ultraintense laser propagation in critical density plasma.

We use one- and two-dimensional particle-in-cell simulations to demonstrate that the propagation of an ultraintense laser (I=10(19)W/cm(2)) in critical density plasma can be interfered with by a high density plasma wall region generated at the propagation front. When the electron flow speed of the wall region exceeds a certain relativistic threshold, the region behaves as an overdense plasma due to a decrease of the effective critical density. The region forms then very small overdense plasma islands. The islands impede the propagation intermittently and slow down the propagation speed significantly.

Channeling of multikilojoule high-intensity laser beams in an inhomogeneous plasma.

Channeling experiments were performed that demonstrate the transport of high-intensity (>10(18)W/cm(2)), multikilojoule laser light through a millimeter-sized, inhomogeneous (∼300-µm density scale length) laser-produced plasma up to overcritical density, which is an important step forward for the fast-ignition concept. The background plasma density and the density depression inside the channel were characterized with a novel optical probe system. The channel progression velocity was measured, which agrees well with theoretical predictions based on large scale particle-in-cell simulations, confirming scaling laws for the required channeling laser energy and laser pulse duration, which are important parameters for future integrated fast-ignition channeling experiments.

Thromboelastometry-guided intraoperative haemostatic management reduces bleeding and red cell transfusion after paediatric cardiac surgery.

BACKGROUND: Thromboelastometric evaluation of coagulation might be useful for prediction and management of bleeding after paediatric cardiac surgery. We tested the hypothesis that the use of a thromboelastometry-guided algorithm for blood product management reduces blood loss and transfusion requirements. METHODS: We studied 78 patients undergoing paediatric cardiac surgery with cardiopulmonary bypass (CPB) for the initial 12 h after operation. Stepwise multiple linear regression was used to develop an algorithm to guide blood product transfusions. Thereafter, we randomly assigned 100 patients to conventional or algorithm-guided blood product management, and assessed bleeding and red cell transfusion requirements. RESULTS: CPB time, post-bypass rotational thromboelastometry (ROTEM(®)) EXTEM amplitude at 10 min (A10), and FIBTEM-A10 were independently associated with chest tube drainage volume during the initial 12 h after operation. Discriminative analysis determined cut-off values of 30 mm for EXTEM-A10 and 5 mm for FIBTEM-A10, and estimated optimal intraoperative fresh-frozen plasma and platelet concentrate transfusion volumes. Thromboelastometry-guided post-bypass blood product management significantly reduced postoperative bleeding (9 vs 16 ml kg(-1), P<0.001) and packed red cell transfusion requirement (11 vs 23 ml kg(-1), P=0.005) at 12 h after surgery, and duration of critical care stay (60 vs 71 h, P=0.014). CONCLUSIONS: Rotational thromboelastometry-guided early haemostatic intervention by rapid intraoperative correction of EXTEM-A10 and FIBTEM-A10 reduced blood loss and red cell transfusion requirements after CPB, and reduced critical care duration in paediatric cardiac surgical patients. CLINICAL TRIAL REGISTRATION: UMIN Clinical Trials Registry UMIN000006832 (December 4, 2011).

Usefulness of standard plasma coagulation tests in the management of perioperative coagulopathic bleeding: is there any evidence?

Standard laboratory coagulation tests (SLTs) such as prothrombin time/international normalized ratio or partial thromboplastin time are frequently used to assess coagulopathy and to guide haemostatic interventions. However, this has been challenged by numerous reports, including the current European guidelines for perioperative bleeding management, which question the utility and reliability of SLTs in this setting. Furthermore, the arbitrary definition of coagulopathy (i.e. SLTs are prolonged by more than 1.5-fold) has been questioned. The present study aims to review the evidence for the usefulness of SLTs to assess coagulopathy and to guide bleeding management in the perioperative and massive bleeding setting. Medline was searched for investigations using results of SLTs as a means to determine coagulopathy or to guide bleeding management, and the outcomes (i.e. blood loss, transfusion requirements, mortality) were reported. A total of 11 guidelines for management of massive bleeding or perioperative bleeding and 64 studies investigating the usefulness of SLTs in this setting were identified and were included for final data synthesis. Referenced evidence for the usefulness of SLTs was found in only three prospective trials, investigating a total of 108 patients (whereby microvascular bleeding was a rare finding). Furthermore, no data from randomized controlled trials support the use of SLTs. In contrast, numerous investigations have challenged the reliability of SLTs to assess coagulopathy or guide bleeding management. There is actually no sound evidence from well-designed studies that confirm the usefulness of SLTs for diagnosis of coagulopathy or to guide haemostatic therapy.

Measuring the strong electrostatic and magnetic fields with proton radiography for ultra-high intensity laser channeling on fast ignition.

In order to investigate the intense laser propagation and channel formation in dense plasma, we conducted an experiment with proton deflectometry on the OMEGA EP Laser facility. The proton image was analyzed by tracing the trajectory of mono-energetic protons, which provides understanding the electric and magnetic fields that were generated around the channel. The estimated field strengths (E ∼ 10(11) V/m and B ∼ 10(8) G) agree with the predictions from 2D-Particle-in-cell (PIC) simulations, indicating the feasibility of the proton deflectometry technique for over-critical density plasma.