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PubMed Journals Articles About "GALACTIC" RSS

17:36 EDT 19th April 2018 | BioPortfolio

GALACTIC PubMed articles on BioPortfolio. Our PubMed references draw on over 21 million records from the medical literature. Here you can see the latest GALACTIC articles that have been published worldwide.

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We have published hundreds of GALACTIC news stories on BioPortfolio along with dozens of GALACTIC Clinical Trials and PubMed Articles about GALACTIC for you to read. In addition to the medical data, news and clinical trials, BioPortfolio also has a large collection of GALACTIC Companies in our database. You can also find out about relevant GALACTIC Drugs and Medications on this site too.

Showing "GALACTIC" PubMed Articles 1–25 of 28

Two chemically similar stellar overdensities on opposite sides of the plane of the Galactic disk.

Our Galaxy is thought to have an active evolutionary history, dominated over the past ten billion years or so by star formation, the accretion of cold gas and, in particular, the merging of clumps of baryonic and dark matter. The stellar halo-the faint, roughly spherical component of the Galaxy-reveals rich 'fossil' evidence of these interactions, in the form of stellar streams, substructures and chemically distinct stellar components. The effects of interactions with dwarf galaxies on the content and morph...


Simulation of the GCR spectrum in the Mars curiosity rover's RAD detector using MCNP6.

The paper presents results from MCNP6 simulations of galactic cosmic ray (GCR) propagation down through the Martian atmosphere to the surface and comparison with RAD measurements made there. This effort is part of a collaborative modeling workshop for space radiation hosted by Southwest Research Institute (SwRI). All modeling teams were tasked with simulating the galactic cosmic ray (GCR) spectrum through the Martian atmosphere and the Radiation Assessment Detector (RAD) on-board the Curiosity rover. The de...

Dark Kinetic Heating of Neutron Stars and an Infrared Window on WIMPs, SIMPs, and Pure Higgsinos.

We identify a largely model-independent signature of dark matter (DM) interactions with nucleons and electrons. DM in the local galactic halo, gravitationally accelerated to over half the speed of light, scatters against and deposits kinetic energy into neutron stars, heating them to infrared blackbody temperatures. The resulting radiation could potentially be detected by the James Webb Space Telescope, the Thirty Meter Telescope, or the European Extremely Large Telescope. This mechanism also produces optic...


The radiation environment on the surface of Mars - Numerical calculations of the galactic component with GEANT4/PLANETOCOSMICS.

Galactic cosmic radiation and secondary particles produced in the interaction with the atmosphere lead to a complex radiation field on the Martian surface. A workshop ("1st Mars Space Radiation Modeling Workshop") organized by the MSL-RAD science team was held in June 2016 in Boulder with the goal to compare models capable to predict this radiation field with each other and measurements from the RAD instrument onboard the curiosity rover taken between November 15, 2015 and January 15, 2016. In this work the...

Recognizing Axionic Dark Matter by Compton and de Broglie Scale Modulation of Pulsar Timing.

Light axionic dark matter, motivated by string theory, is increasingly favored for the "no weakly interacting massive particle era". Galaxy formation is suppressed below a Jeans scale of ≃10^{8}  M_{⊙} by setting the axion mass to m_{B}∼10^{-22}  eV, and the large dark cores of dwarf galaxies are explained as solitons on the de Broglie scale. This is persuasive, but detection of the inherent scalar field oscillation at the Compton frequency ω_{B}=(2.5  months)^{-1}(m_{B}/10^{-22}  eV)...

Directional Sensitivity in Light-Mass Dark Matter Searches with Single-Electron-Resolution Ionization Detectors.

We propose a method using solid state detectors with directional sensitivity to dark matter interactions to detect low-mass weakly interacting massive particles (WIMPs) originating from galactic sources. In spite of a large body of literature for high-mass WIMP detectors with directional sensitivity, no available technique exists to cover WIMPs in the mass range

Comparing HZETRN, SHIELD, FLUKA and GEANT transport codes.

For the first time, the American (NASA) and Russian (ROSCOSMOS) space radiation transport codes, HZETRN and SHIELD respectively, are directly compared to each other. Calculations are presented for Galactic Cosmic Ray (GCR) minimum Hydrogen, Oxygen and Iron projectiles incident on a uniform Aluminum cylinder of varying thickness. Comparisons are made for the flux spectra of neutrons, light ions (Z≤ 2), heavy ions (Z> 2) and pions emitted from the back of the Aluminum cylinder. In order to provide more benc...

DEVELOPMENT, VALIDATION AND DEMONSTRATION OF THE NTHU FLIGHT DOSE CALCULATOR.

Galactic cosmic-ray-induced air showers constitute the largest source of radiation exposure for aircrew and passengers. To facilitate the evaluation of effective doses received by this population, a database containing dose rates of various radiation components in the atmosphere was established; the parameterization accounted for altitude, geomagnetic rigidity and solar modulation. Energy spectra of secondary cosmic rays and effective dose rates were calculated using the FLUKA Monte Carlo code. An auxiliary...

CONTRIBUTION OF DIFFERENT PARTICLES MEASURED WITH TRACK ETCHED DETECTORS ONBOARD ISS.

Cosmic radiation consists of primary high-energy galactic and solar particles. When passing through spacecraft walls and astronauts' bodies, the spectrum becomes even more complex due to generating of secondary particles through fragmentation and nuclear interactions. Total radiation exposure is contributed by both these components. With an advantage, space research uses track etched detectors from the group of passive detectors visualizing the tracks of particles, in this case by etching. The detectors can...

Search for Dark Matter Annihilation in Galaxy Groups.

We use 413 weeks of publicly available Fermi Pass 8 gamma-ray data combined with recently developed galaxy group catalogs to search for evidence of dark matter annihilation in extragalactic halos. In our study, we use luminosity-based mass estimates and mass-to-concentration relations to infer the J factors and associated uncertainties for hundreds of galaxy groups within a redshift range z≲0.03. We employ a conservative substructure boost factor model, which only enhances the sensitivity by an O(1) facto...

The radiation environment on the surface of Mars - Summary of model calculations and comparison to RAD data.

The radiation environment at the Martian surface is, apart from occasional solar energetic particle events, dominated by galactic cosmic radiation, secondary particles produced in their interaction with the Martian atmosphere and albedo particles from the Martian regolith. The highly energetic primary cosmic radiation consists mainly of fully ionized nuclei creating a complex radiation field at the Martian surface. This complex field, its formation and its potential health risk posed to astronauts on future...

Rotational Spectroscopy of the Lowest Energy Conformer of 2-Cyanobutane.

Iso-propyl cyanide was recently detected in space as the first branched alkyl compound. Its abundance with respect to n-propyl cyanide in the Galactic center source Sagittarius B2(N2) is about 0.4. Astrochemical model calculations suggest that for the heavier homolog butyl cyanide the branched isomers dominate over the unbranched n-butyl cyanide and that 2-cyanobutane is the most abundant isomer. We have studied the rotational spectrum of 2-cyanobutane between 2 and 24 GHz using Fourier transform microwave ...

Long-Term Deficits in Behavior Performances Caused by Low- and High-Linear Energy Transfer Radiation.

Efforts to protect astronauts from harmful galactic cosmic radiation (GCR) require a better understanding of the effects of GCR on human health. In particular, little is known about the lasting effects of GCR on the central nervous system (CNS), which may lead to behavior performance deficits. Previous studies have shown that high-linear energy transfer (LET) radiation in rodents leads to short-term declines in a variety of behavior tests. However, the lasting impact of low-, medium- and high-LET radiation ...

Evaluation of HZETRN on the Martian surface: Sensitivity tests and model results.

The Mars Science Laboratory Radiation Assessment Detector (MSLRAD) is providing continuous measurements of dose, dose equivalent, and particle flux on the surface of Mars. These measurements have been highly useful in validating environmental and radiation transport models that will be heavily relied upon for future deep space missions. In this work, the HZETRN code is utilized to estimate radiation quantities of interest on the Martian surface. A description of the modeling approach used with HZETRN is giv...

A large oxygen-dominated core from the seismic cartography of a pulsating white dwarf.

White-dwarf stars are the end product of stellar evolution for most stars in the Universe. Their interiors bear the imprint of fundamental mechanisms that occur during stellar evolution. Moreover, they are important chronometers for dating galactic stellar populations, and their mergers with other white dwarfs now appear to be responsible for producing the type Ia supernovae that are used as standard cosmological candles. However, the internal structure of white-dwarf stars-in particular their oxygen conten...

MMR Deficiency Does Not Sensitize or Compromise the Function of Hematopoietic Stem Cells to Low and High LET Radiation.

One of the major health concerns on long-duration space missions will be radiation exposure to the astronauts. Outside the earth's magnetosphere, astronauts will be exposed to galactic cosmic rays (GCR) and solar particle events that are principally composed of protons and He, Ca, O, Ne, Si, Ca, and Fe nuclei. Protons are by far the most common species, but the higher atomic number particles are thought to be more damaging to biological systems. Evaluation and amelioration of risks from GCR exposure will be...

A clumpy and anisotropic galaxy halo at redshift 1 from gravitational-arc tomography.

Every star-forming galaxy has a halo of metal-enriched gas that extends out to at least 100 kiloparsecs, as revealed by the absorption lines that this gas imprints on the spectra of background quasars. However, quasars are sparse and typically probe only one narrow beam of emission through the intervening galaxy. Close quasar pairs and gravitationally lensed quasars have been used to circumvent this inherently one-dimensional technique, but these objects are rare and the structure of the circumgalactic medi...

Radiation transport simulation of the Martian GCR surface flux and dose estimation using spherical geometry in PHITS compared to MSL-RAD measurements.

Planetary bodies and spacecraft are predominantly exposed to isotropic radiation environments that are subject to transport and interaction in various material compositions and geometries. Specifically, the Martian surface radiation environment is composed of galactic cosmic radiation, secondary particles produced by their interaction with the Martian atmosphere, albedo particles from the Martian regolith and occasional solar particle events. Despite this complex physical environment with potentially signif...

On the Formation of Hydroxylamine in Low-Temperature Interstellar Model Ices.

We irradiated binary ice mixtures of ammonia (NH3) and oxygen (O2) ices at astrophysically relevant temperatures of 5.5 K with energetic electrons to mimic the energy transfer process that occur in the track of galactic cosmic-rays (GCRs). By monitoring the newly formed molecules online and in situ utilizing Fourier transform infrared spectroscopy (FTIR) complemented by temperature programmed desorption (TPD) studies with single photon reflectron time-of-flight mass spectroscopy (PI-ReTOF-MS), the synthesis...

Effects of (1)H + (16)O Charged Particle Irradiation on Short-Term Memory and Hippocampal Physiology in a Murine Model.

Radiation from galactic cosmic rays (GCR) poses a significant health risk for deep-space flight crews. GCR are unique in their extremely high-energy particles. With current spacecraft shielding technology, some of the predominant particles astronauts would be exposed to are (1)H + (16)O. Radiation has been shown to cause cognitive deficits in mice. The hippocampus plays a key role in memory and cognitive tasks; it receives information from the cortex, undergoes dendritic-dependent processing and then relays...

Delayed effects of accelerated heavy ions on the induction of HPRT mutations in V79 hamster cells.

Fundamental research on the harmful effects of ionizing radiation on living cells continues to be of great interest. Recently, priority has been given to the study of high-charge and high-energy (HZE) ions that comprise a substantial part of the galactic cosmic ray (GCR) spectra that would be encountered during long-term space flights. Moreover, predictions of the delayed genetic effects of high linear energy transfer (LET) exposure is becoming more important as heavy ion therapy use is increasing. This wor...

NASA GeneLab Project: Bridging Space Radiation Omics with Ground Studies.

Accurate assessment of risks of long-term space missions is critical for human space exploration. It is essential to have a detailed understanding of the biological effects on humans living and working in deep space. Ionizing radiation from galactic cosmic rays (GCR) is a major health risk factor for astronauts on extended missions outside the protective effects of the Earth's magnetic field. Currently, there are gaps in our knowledge of the health risks associated with chronic low-dose, low-dose-rate ioniz...

A calculation of the radiation environment on the Martian surface.

In this work, the radiation environment on the Martian surface, as produced by galactic cosmic radiation incident on the atmosphere, is modeled using the Monte Carlo radiation transport code, High Energy Transport Code-Human Exploration and Development in Space (HETC-HEDS). This work is performed in participation of the 2016 Mars Space Radiation Modeling Workshop held in Boulder, CO, and is part of a larger collaborative effort to study the radiation environment on the surface of Mars. Calculated fluxes for...

Blazar spectral variability as explained by a twisted inhomogeneous jet.

Blazars are active galactic nuclei, which are powerful sources of radiation whose central engine is located in the core of the host galaxy. Blazar emission is dominated by non-thermal radiation from a jet that moves relativistically towards us, and therefore undergoes Doppler beaming. This beaming causes flux enhancement and contraction of the variability timescales, so that most blazars appear as luminous sources characterized by noticeable and fast changes in brightness at all frequencies. The mechanism t...

Quantitative Proteomic Analysis of the Hippocampus of Rats with GCR-Induced Spatial Memory Impairment.

NASA is planning future missions to Mars, which will result in astronauts being exposed to ∼13 cGy/year of galactic cosmic radiation (GCR). Previous ground-based experiments have demonstrated that low (15 cGy) doses of 1 GeV/n 56Fe ions impair hippocampus-dependent spatial memory in rats. However, some irradiated rats maintain a spatial memory performance comparable to that seen in the sham-irradiated rats, suggesting that some of these animals are able to ameliorate the deleterious effects of the GCR, wh...


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