Kilotesla plasmoid formation by a trapped relativistic laser beam.

A strong quasistationary magnetic field is generated in hollow targets with curved internal surface under the action of a relativistically intense picosecond laser pulse. Experimental data evidence the formation of quasistationary strongly magnetized plasma structures decaying on a hundred picoseconds timescale, with the magnetic field strength of the kilotesla scale. Numerical simulations unravel the importance of transient processes during the magnetic field generation and suggest the existence of fast and slow regimes of plasmoid evolution depending on the interaction parameters. The proposed setup is suited for perspective highly magnetized plasma application and fundamental studies.

Neural network analysis of quasistationary magnetic fields in microcoils driven by short laser pulses.

Optical generation of kilo-tesla scale magnetic fields enables prospective technologies and fundamental studies with unprecedentedly high magnetic field energy density. A question is the optimal configuration of proposed setups, where plenty of physical phenomena accompany the generation and complicate both theoretical studies and experimental realizations. Short laser drivers seem more suitable in many applications, though the process is tangled by an intrinsic transient nature. In this work, an artificial neural network is engaged for unravelling main features of the magnetic field excited with a picosecond laser pulse. The trained neural network acquires an ability to read the magnetic field values from experimental data, extremely facilitating interpretation of the experimental results. The conclusion is that the short sub-picosecond laser pulse may generate a quasi-stationary magnetic field structure living on a hundred picosecond time scale, when the induced current forms a closed circuit.

Dosimetric calibration of GafChromic HD-V2, MD-V3, and EBT3 films for dose ranges up to 100 kGy.

A dosimetric calibration of three types of radiochromic films (GafChromicTM HD-V2, MD-V3, and EBT3) was carried out for absorbed doses (D) ranging up to 100 kGy using a 130 TBq Co60 γ-ray source. The optical densities (ODs) of the irradiated films were acquired with the transmission-mode flatbed film scanner EPSON GT-X980. The calibration data were cross-checked using the 20-MeV proton beam from the azimuthally varying field cyclotron at the Research Center for Nuclear Physics in Osaka University. These experimental results not only present the measurable dose ranges of the films depending on the readout wavelength, but also show consistency with our hypothesis that the OD response curve [log(OD)-log(D) curve] is determined by the volumetric average of the absorption dose and does not strongly depend on the type of radiation for the excitation.

Relativistic magnetic reconnection in laser laboratory for testing an emission mechanism of hard-state black hole system.

Magnetic reconnection in a relativistic electron magnetization regime was observed in a laboratory plasma produced by a high-intensity, large energy, picoseconds laser pulse. Magnetic reconnection conditions realized with a laser-driven several kilotesla magnetic field is comparable to that in the accretion disk corona of black hole systems, i.e., Cygnus X-1. We observed particle energy distributions of reconnection outflow jets, which possess a power-law component in a high-energy range. The hardness of the observed spectra could explain the hard-state x-ray emission from accreting black hole systems.

Ultrafast probing of magnetic field growth inside a laser-driven solenoid.

We report on the detection of the time-dependent B-field amplitude and topology in a laser-driven solenoid. The B-field inferred from both proton deflectometry and Faraday rotation ramps up linearly in time reaching 210 ± 35 T at the end of a 0.75-ns laser drive with 1 TW at 351 nm. A lumped-element circuit model agrees well with the linear rise and suggests that the blow-off plasma screens the field between the plates leading to an increased plate capacitance that converts the laser-generated hot-electron current into a voltage source that drives current through the solenoid. ALE3D modeling shows that target disassembly and current diffusion may limit the B-field increase for longer laser drive. Scaling of these experimental results to a National Ignition Facility (NIF) hohlraum target size (∼0.2cm^{3}) indicates that it is possible to achieve several tens of Tesla.

Tuberculosis in HIV-positive patients: cellular response and immune activation in the lung.

The host response to Mycobacterium tuberculosis is dependent on the accumulation and activation of cytotoxic and memory CD4+ T cells, resulting in granuloma formation and delayed type hypersensitivity. We characterized the cellular response of radiographically involved lung segments from 17 HIV-positive and 11 HIV-negative patients with acute tuberculosis (TB) using bronchoalveolar lavage (BAL) and compared the response to uninvolved segments, normal control subjects and peripheral blood. In both HIV-positive and HIV-negative patients, radiographically involved segments had significantly increased numbers of total cells per milliliter, percent of neutrophils recovered, and percent of lymphocytes recovered compared with uninvolved segments or normal control subjects, but HIV-positive patients had a lower proportion of lymphocytes in the involved segments than HIV-negative patients with tuberculosis (19 +/- 5% versus 33 +/- 5%; p < 0.05). Lymphocyte subset analysis demonstrated that HIV-positive patients had markedly reduced percentages of CD4+ lymphocytes (CD4+ lymphocytes in HIV-positive TB involved site 25 +/- 6%; HIV-negative TB involved site 73 +/- 2%; p < 0.01) and an increase in the percentage of CD8+ lymphocytes (HIV positive involved site 61 +/- 6% versus HIV negative involved site 19 +/- 3%; p < 0.01). Immunohistochemistry of lung biopsy tissue in five HIV-negative patients showed similar lymphocyte subset profiles as BAL, indicating that BAL reflects cell populations in tissue granulomas. BAL lymphocytes from four HIV-positive and four HIV-negative tuberculosis patients demonstrated immune activation by staining with a murine antibody to TIA-1, a cytoplasmic protein associated with cytotoxicity and apoptosis (HIV positive 48 +/- 6%, HIV negative 31 +/- 7%, normals 11 +/- 5%). Steady state mRNA for gamma-interferon was decreased in four HIV-positive patients when compared with four HIV-negative patients. IL-8 production was comparable in HIV-negative and HIV-positive patients with focal disease but reduced in two patients with miliary tuberculosis. We conclude that HIV-positive patients with+ tuberculosis have a reduced enrichment and activation of immune cells in the lung, and this failure of a CD4+ alveolitis limits an effective immune response.

Pulmonary cryptococcosis mimicking methotrexate pneumonitis.

An 81-year-old man being treated with weekly low dose methotrexate (MTX) for psoriasis was admitted with a 2-month history of cough, shortness of breath and 7% eosinophilia in the peripheral blood. Chest roentgenogram revealed bilateral alveolar and interstitial infiltrates. Although the clinical presentation suggested MTX pneumonitis, a transbronchial lung biopsy established a diagnosis of pulmonary cryptococcosis. Pulmonary cryptococcosis should be included in the list of infectious processes that can mimic MTX pneumonitis.