Abstract
The scientific and technical advances continue to support novel discoveries by allowing scientists to acquire new insights into the structure and properties of matter using new tools and ...sources. Notably, neutrons are among the most valuable sources in providing such a capability. At the Institute of Laser Engineering, Osaka, the first steps are taken towards the development of a table-top laser-driven neutron source, capable of producing a wide range of energies with high brightness and temporal resolution. By employing a pure hydrogen moderator, maintained at cryogenic temperature, a cold neutron (
$$\le 25\hbox { meV}$$
≤
25
meV
) flux of
$$\sim 2\times 10^3\hbox { n/cm}^2$$
∼
2
×
10
3
n/cm
2
/pulse was measured at the proximity of the moderator exit surface. The beam duration of hundreds of ns to tens of
$$\upmu \hbox {s}$$
μ
s
is evaluated for neutron energies ranging from 100s keV down to meV via Monte-Carlo techniques. Presently, with the upcoming J-EPoCH high repetition rate laser at Osaka University, a cold neutron flux in orders of
$$\sim 1\times 10^{9}\hbox { n/cm}^2/\hbox {s}$$
∼
1
×
10
9
n/cm
2
/
s
is expected to be delivered at the moderator in a compact beamline.
Lipids and HCV Bassendine, M. F.; Sheridan, D. A.; Bridge, S. H. ...
Seminars in immunopathology,
2013/1, Volume:
35, Issue:
1
Journal Article
Peer reviewed
Chronic hepatitis C virus (HCV) infection is associated with an increase in hepatic steatosis and a decrease in serum levels of total cholesterol, low-density lipoprotein cholesterol (LDL) and ...apolipoprotein B (apoB), the main protein constituent of LDL and very low-density lipoprotein (VLDL). These changes are more marked in HCV genotype 3 infection, and effective treatment results in their reversal. Low lipid levels in HCV infection correlate not only with steatosis and more advanced liver fibrosis but also with non-response to interferon-based therapy. The clinical relevance of disrupted lipid metabolism reflects the fact that lipids play a crucial role in the life cycle of hepatitis C virus. HCV assembly and maturation in hepatocytes depend on microsomal triglyceride transfer protein and apoB in a manner that parallels the formation of VLDL. VLDL production from the liver occurs throughout the day with an estimated 10
18
particles produced every 24 h whilst the estimated hepatitis C virion production rate is 10
12
virions per day. HCV particles in the serum exist as a mixture of complete low-density infectious lipo-viral particles (LVP) and a vast excess of apoB-associated empty nucleocapsid-free sub-viral particles that are complexed with anti-HCV envelope antibodies. Apolipoprotein E (apoE) is also involved in HCV particle morphogenesis and is an essential apolipoprotein for HCV infectivity. ApoE is a critical ligand for the receptor-mediated removal of triglyceride rich lipoprotein (TRL) remnants by the liver. The dynamics of apoB-associated lipoproteins, including HCV-LVP, change post-prandially with an increase in large TRL remnants and very low density HCV-LVP which are rapidly cleared by the liver (at least three HCV receptors are cellular receptors for uptake of TRL remnants). In summary, HCV utilises triglyceride-rich lipoprotein pathways within the liver and the circulation to its advantage.
The water channel AQP4 is concentrated in perivascular and subpial membrane domains of brain astrocytes. These membranes form the interface between the neuropil and extracerebral liquid spaces. AQP4 ...is anchored at these membranes by its carboxyl terminus to α-syntrophin, an adapter protein associated with dystrophin. To test functions of the perivascular AQP4 pool, we studied mice homozygous for targeted disruption of the gene encoding$\alpha\!-\!syntrophin\>(\alpha\!-\!Syn^{-/-})$. These animals show a marked loss of AQP4 from perivascular and subpial membranes but no decrease in other membrane domains, as judged by quantitative immunogold electron microscopy. In the basal state, perivascular and subpial astroglial end-feet were swollen in brains of α-Syn-/-mice compared to WT mice, suggesting reduced clearance of water generated by brain metabolism. When stressed by transient cerebral ischemia, brain edema was attenuated in α-Syn-/-mice, indicative of reduced water influx. Surprisingly, AQP4 was strongly reduced but α-syntrophin was retained in perivascular astroglial end-feet in WT mice examined 23 h after transient cerebral ischemia. Thus α-syntrophin-dependent anchoring of AQP4 is sensitive to ischemia, and loss of AQP4 from this site may retard the dissipation of postischemic brain edema. These studies identify a specific, syntrophin-dependent AQP4 pool that is expressed at distinct membrane domains and which mediates bidirectional transport of water across the brain-blood interface. The anchoring of AQP4 to α-syntrophin may be a target for treatment of brain edema, but therapeutic manipulations of AQP4 must consider the bidirectional water flux through this molecule.
We report on the selective acceleration of carbon ions during the interaction of ultrashort, circularly polarized and contrast-enhanced laser pulses, at a peak intensity of 5.5 × 1020 W/cm2, with ...ultrathin carbon foils. Under optimized conditions, energies per nucleon of the bulk carbon ions reached significantly higher values than the energies of contaminant protons ( 33 MeV / nucleon vs 18 MeV), unlike what is typically observed in laser-foil acceleration experiments. Experimental data, and supporting simulations, emphasize different dominant acceleration mechanisms for the two ion species and highlight an (intensity dependent) optimum thickness for radiation pressure acceleration; it is suggested that the preceding laser energy reaching the target before the main pulse arrives plays a key role in a preferential acceleration of the heavier ion species.
Ion acceleration driven by the interaction of an ultraintense (2 × 1020 W cm−2) laser pulse with an ultrathin ( nm) foil target is experimentally and numerically investigated. Protons accelerated by ...sheath fields and via laser radiation pressure are angularly separated and identified based on their directionality and signature features (e.g. transverse instabilities) in the measured spatial-intensity distribution. A low divergence, high energy proton component is also detected when the heated target electrons expand and the target becomes relativistically transparent during the interaction. 2D and 3D particle-in-cell simulations indicate that under these conditions a plasma jet is formed at the target rear, supported by a self-generated azimuthal magnetic field, which extends into the expanded layer of sheath-accelerated protons. Electrons trapped within this jet are directly accelerated to super-thermal energies by the portion of the laser pulse transmitted through the target. The resulting streaming of the electrons into the ion layers enhances the energy of protons in the vicinity of the jet. Through the addition of a controlled prepulse, the maximum energy of these protons is demonstrated experimentally and numerically to be sensitive to the picosecond rising edge profile of the laser pulse.
The spatio-temporal and polarisation properties of intense light is important in wide-ranging topics at the forefront of extreme light-matter interactions, including ultrafast laser-driven particle ...acceleration, attosecond pulse generation, plasma photonics, high-field physics and laboratory astrophysics. Here, we experimentally demonstrate modifications to the polarisation and temporal properties of intense light measured at the rear of an ultrathin target foil irradiated by a relativistically intense laser pulse. The changes are shown to result from a superposition of coherent radiation, generated by a directly accelerated bipolar electron distribution, and the light transmitted due to the onset of relativistic self-induced transparency. Simulations show that the generated light has a high-order transverse electromagnetic mode structure in both the first and second laser harmonics that can evolve on intra-pulse time-scales. The mode structure and polarisation state vary with the interaction parameters, opening up the possibility of developing this approach to achieve dynamic control of structured light fields at ultrahigh intensities.
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