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.

Interrelations of Cerebral Hemodynamics with Parameters of Cardiac Function and Brain Tissue in Patients with Ischemic Stroke.

We analyzed interrelations between the cerebral blood flow, cardiac output, and condition of the brain substance in 530 patients with ischemic stroke. Dependencies between the linear blood flow velocities in all arteries supplying the brain, as well as between the total volume blood flow through the internal carotid arteries and left ventricular stroke volume were revealed. The severity of atrophy was maximum in the parietal lobes (median 1.5 (1.0; 2.0)) and minimum in the occipital lobes (median 0.5 (0; 1.0)). Temporal lobes cortical atrophy significantly correlated with changes in the limbic system and in the periventricular and deep white matter; a significant weak inverse correlation of this parameter with blood flow in the middle cerebral artery was also found. Changes in the periventricular white matter (but not in deep white matter) demonstrated a significant inverse correlation with blood flow in the middle and anterior cerebral arteries.

Observations of neutron radiation environment during Odyssey cruise to Mars.

In April 2001, Mars Odyssey spacecraft with the High Energy Neutron Detector (HEND) onboard was launched to Mars. HEND/Odyssey was switched on measurement mode for most of transit to Mars to monitor variations of spacecraft background and solar activity. Although HEND/Odyssey was originally designed to measure Martian neutron albedo and to search for Martian subsurface water/water ice, its measurements during cruise phase to Mars are applicable to evaluate spacecraft ambient radiation background. The biological impact of the neutron component of this radiation background should be understood, as it must be taken into account in planning future human missions to Mars. We have modeled the spacecraft neutron spectral density and compared it with HEND measurements to estimate neutron dose equivalent rates during Odyssey cruise phase, which occurred during the maximum period of solar cycle 23. We find that the Odyssey ambient neutron environment during May - September 2001 yields 10.6 ± 2.0 µSv per day in the energy range from 0 to 15 MeV, and about 29 µSv per day when extrapolated to the 0-1000 MeV energy range during solar quiet time (intervals without Solar Particle Events, SPEs). We have also extrapolated HEND/Odyssey measurements to different periods of solar cycle and find that during solar minimum (maximum of GCR flux), the neutron dose equivalent rate during cruise to Mars could be as high as 52 µSv per day with the same shielding. These values are in good agreement with results reported for a similar measurement made with an instrument aboard the Mars Science Laboratory during its cruise to Mars in 2011-2012.

A bright γ-ray flare interpreted as a giant magnetar flare in NGC 253.

Soft γ-ray repeaters exhibit bursting emission in hard X-rays and soft γ-rays. During the active phase, they emit random short (milliseconds to several seconds long), hard-X-ray bursts, with peak luminosities1 of 1036 to 1043 erg per second. Occasionally, a giant flare with an energy of around 1044 to 1046 erg is emitted2. These phenomena are thought to arise from neutron stars with extremely high magnetic fields (1014 to 1015 gauss), called magnetars1,3,4. A portion of the second-long initial pulse of a giant flare in some respects mimics short γ-ray bursts5,6, which have recently been identified as resulting from the merger of two neutron stars accompanied by gravitational-wave emission7. Two γ-ray bursts, GRB 051103 and GRB 070201, have been associated with giant flares2,8-11. Here we report observations of the γ-ray burst GRB 200415A, which we localized to a 20-square-arcmin region of the starburst galaxy NGC 253, located about 3.5 million parsecs away. The burst had a sharp, millisecond-scale hard spectrum in the initial pulse, which was followed by steady fading and softening over 0.2 seconds. The energy released (roughly 1.3 × 1046 erg) is similar to that of the superflare5,12,13 from the Galactic soft γ-ray repeater SGR 1806-20 (roughly 2.3 × 1046 erg). We argue that GRB 200415A is a giant flare from a magnetar in NGC 253.

Proof-of-principle experiment for laser-driven cold neutron source.

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 ([Formula: see text]) flux of [Formula: see text]/pulse was measured at the proximity of the moderator exit surface. The beam duration of hundreds of ns to tens of [Formula: see text] 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 [Formula: see text] is expected to be delivered at the moderator in a compact beamline.

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.

Electromagnetic Burst Generation during Annihilation of Magnetic Field in Relativistic Laser-Plasma Interaction.

We present the results of theoretical studies of formation and evolution of the current sheet in a colliosionless plasma during magnetic reconnection in relativistic limit. Relativistic magnetic reconnection is driven by parallel laser pulses interacting with underdense plasma target. Annihilation of laser created magnetic field of opposite polarity generates strong non-stationary electric field formed in between the region with opposite polarity magnetic field accelerating charged particles within the current sheet. This laser-plasma target configuration is discussed in regard with the laboratory modeling of charged particle acceleration and gamma flash generation in astrophysics. We present the results of 3-dimensional kinetic simulations and theoretical studies on the formation and evolution of the current sheet in a collisionless plasma during magnetic field annihilation in the ultra-relativistic limit. Annihilation of oppositively directed magnetic fields driven by two laser pulses interacting with underdense plasma target is accompanied by an electromagnetic burst generation. The induced strong non-stationary longitudinal electric field accelerates charged particles within the current sheet. Properties of the laser-plasma target configuration are discussed in the context of the laboratory modeling for charged particle acceleration and gamma flash generation in astrophysics.

The ADRON-RM Instrument Onboard the ExoMars Rover.

This overview presents the physical principles, design, measurement capabilities, and summary of planned operations of the autonomous detector of radiation of neutrons onboard rover at Mars (ADRON-RM) on the surface of Mars. ADRON-RM is a Russian project selected for the joint European Space Agency-Roscosmos ExoMars 2020 landing mission. A compact passive neutron spectrometer, ADRON-RM, was designed to study the abundance and distribution of water and neutron absorption elements (such as Cl, Fe, and others) in the martian subsurface along the path of the ExoMars rover. Key Words: Mars exploration-Surface-Neutron Spectroscopy-Water. Astrobiology 17, 585-594.

A comparative study of LaBr3(Ce(3+)) and CeBr3 based gamma-ray spectrometers for planetary remote sensing applications.

The recent availability of large volume cerium bromide crystals raises the possibility of substantially improving gamma-ray spectrometer limiting flux sensitivities over current systems based on the lanthanum tri-halides, e.g., lanthanum bromide and lanthanum chloride, especially for remote sensing, low-level counting applications or any type of measurement characterized by poor signal to noise ratios. The Russian Space Research Institute has developed and manufactured a highly sensitive gamma-ray spectrometer for remote sensing observations of the planet Mercury from the Mercury Polar Orbiter (MPO), which forms part of ESA's BepiColombo mission. The Flight Model (FM) gamma-ray spectrometer is based on a 3-in. single crystal of LaBr3(Ce(3+)) produced in a separate crystal development programme specifically for this mission. During the spectrometers development, manufacturing, and qualification phases, large crystals of CeBr3 became available in a subsequent phase of the same crystal development programme. Consequently, the Flight Spare Model (FSM) gamma-ray spectrometer was retrofitted with a 3-in. CeBr3 crystal and qualified for space. Except for the crystals, the two systems are essentially identical. In this paper, we report on a comparative assessment of the two systems, in terms of their respective spectral properties, as well as their suitability for use in planetary mission with respect to radiation tolerance and their propensity for activation. We also contrast their performance with a Ge detector representative of that flown on MESSENGER and show that: (a) both LaBr3(Ce(3+)) and CeBr3 provide superior detection systems over HPGe in the context of minimally resourced spacecraft and (b) CeBr3 is a more attractive system than LaBr3(Ce(3+)) in terms of sensitivities at lower gamma fluxes. Based on the tests, the FM has now been replaced by the FSM on the BepiColombo spacecraft. Thus, CeBr3 now forms the central gamma-ray detection element on the MPO spacecraft.

[Ocular and orbital blood flow in apparently healthy adults].

Doppler measurements of ocular and orbital blood flow at rest were studied using duplex ultrasonography in 30 apparently healthy adult volunteers. The following linear and calculated Doppler measurements were estimated at rest: blood flow in ophthalmic artery (OA), central retinal artery (CRA), posterior ciliary arteries, central retinal vein and superior ophthalmic vein (SOV). In 10 patients Doppler measurements of blood flow in OA, CRA SOV were estimated 5 times by 2 observers with different level of skills in ultrasonographic ophthalmologic examination. Statistic analysis showed strong correlation of linear and calculated measurements in OA, CRA and venous blood flow velocity. A number of Doppler measurements with the most significant inter- and intraobserver variation were revealed. Measurements with high reproducibility were determined. Thus, a unique technique should be performed in estimation of Doppler measurements of blood flow in ocular and orbital vessels. The velocities in the main arteries (OA, CRA) and veins (SOV) were showed to have significant strong interobserver correlation. The highest reproducibility and accuracy was revealed for maximal systolic velocity in OA and CRA and maximal velocity for cardiac cycle in SOV.

Hydrogen mapping of the lunar south pole using the LRO neutron detector experiment LEND.

Hydrogen has been inferred to occur in enhanced concentrations within permanently shadowed regions and, hence, the coldest areas of the lunar poles. The Lunar Crater Observation and Sensing Satellite (LCROSS) mission was designed to detect hydrogen-bearing volatiles directly. Neutron flux measurements of the Moon's south polar region from the Lunar Exploration Neutron Detector (LEND) on the Lunar Reconnaissance Orbiter (LRO) spacecraft were used to select the optimal impact site for LCROSS. LEND data show several regions where the epithermal neutron flux from the surface is suppressed, which is indicative of enhanced hydrogen content. These regions are not spatially coincident with permanently shadowed regions of the Moon. The LCROSS impact site inside the Cabeus crater demonstrates the highest hydrogen concentration in the lunar south polar region, corresponding to an estimated content of 0.5 to 4.0% water ice by weight, depending on the thickness of any overlying dry regolith layer. The distribution of hydrogen across the region is consistent with buried water ice from cometary impacts, hydrogen implantation from the solar wind, and/or other as yet unknown sources.

Experiment LEND of the NASA Lunar Reconnaissance Orbiter for high-resolution mapping of neutron emission of the Moon.

The scientific objectives of neutron mapping of the Moon are presented as 3 investigation tasks of NASA's Lunar Reconnaissance Orbiter mission. Two tasks focus on mapping hydrogen content over the entire Moon and on testing the presence of water-ice deposits at the bottom of permanently shadowed craters at the lunar poles. The third task corresponds to the determination of neutron contribution to the total radiation dose at an altitude of 50 km above the Moon. We show that the Lunar Exploration Neutron Detector (LEND) will be capable of carrying out all 3 investigations. The design concept of LEND is presented together with results of numerical simulations of the instrument's sensitivity for hydrogen detection. The sensitivity of LEND is shown to be characterized by a hydrogen detection limit of about 100 ppm for a polar reference area with a radius of 5 km. If the presence of ice deposits in polar "cold traps" is confirmed, a unique record of many millions of years of lunar history would be obtained, by which the history of lunar impacts could be discerned from the layers of water ice and dust. Future applications of a LEND-type instrument for Mars orbital observations are also discussed.

[Sex chromatin in oncomorphology]. / Polovoi khromatin v onkomorfologii.

SCr body is a label of repression of one of the sex chromosomes (X chromosome in women or Y chromosome in men) in the interphase nucleus. By the end of the synthesis period these chromosomes undergo derepression since DNA replication occurs. Thus, by the end of the synthetic and in premitotic periods of the cellular cycle the SCr body disappears. In tumors of various locations, a clear-cut inverse proportional dependence between a decrease in the number of nuclei with SCr bodies and an increase in the mitotic index was demonstrated. Therefore, the CSr test is an index of the growth rate (proliferative activity) of the examined tumor. By this test it is possible to determine the degree of the tumor progression, to assess the mitotic activity in small pieces of biopsy materials. The SCr test may be an additional method for differential diagnosis of malignant tumors.

[APUD cells and apudomas]. / APUD-kletki i apudomy.

Synthesis of biologically active amines and peptides, and accumulation of them in the cytoplasm in the form of secretory granules of "neuroendocrine" type are among the most important characteristics of APUD cells. Apudomas, tumors consisting of cells with the properties of APUD elements, have many common morphological and functional features, although they are quite heterogeneous by clinical behavior and histogenesis. Histological diagnosis of apudomas requires the assessment of the endocrine function of the tumor cells for which histochemical and electron microscopic methods must be employed, as well as consideration of the clinical and biochemical indices of the hormonal activity of the tumors.

[Angiomyolipoma of the kidneys]. / Angiomiolipomy pochek.

The histological structure and histogenesis of three renal angiomyolipomas have been studied. Of special interest are peculiar small cells showing all kinds of transition to mature components of angiomyolipoma: fat tissue, smooth muscles, vessels. These cells are referred to as cambial tumor elements, which presumably arise from mature renal tissues of the mesodermal nature through their dedifferentiation. The specific feature of angiolipomas as true tumors is varied differentiation of the tumor cambium that conditions great variety of their histological structure.

[So-called lymphoepithelioma of the lymphoid pharyngeal ring]. / Tak nazyvaemaia limfoépitelioma limfoidnogo glotochnogo kol'tsa.

A retrospective analysis of 43 observations of "lymphoepitheliomas" has shown that in 34 cases this diagnosis was referred to low-differentiated cancer with lymphocytic infiltration, and in 9 cases--to reticulosarcomas (an epitheliod variant). The authors suggest some signs as an adjunct for the differential diagnosis between an epithelioid variant of reticulosarcoma and low-differentiated cancer. It is necessary to exclude lymphocytic epithelioma as an onconosollogical unit, since it does not exist as a double-tissue tumor.

[Follicular lymphoma]. / Follikuliarnaia limfoma.

Follicular lymphoma is regarded as reticulosarcoma in situ. Tumor nodules are represented by neoplastic foci of the tumor tissue. They can show the structure of lymphoblastic, reticulocellular and polymorphocellular reticulosarcoma. The Maximov cambial lymphocyte is assumed to be the most reliable cell source. The Willis teaching on tumor field holds good of the morphogenesis of follicular lymphomas. The problem of the differential diagnosis between follicular lymphomas and follicular reactive hyperplasia is discussed.