The Mars Science Laboratory spacecraft, containing the Curiosity rover, was launched to Mars on 26 November 2011, and for most of the 253-day, 560-million-kilometer cruise to Mars, the Radiation ...Assessment Detector made detailed measurements of the energetic particle radiation environment inside the spacecraft. These data provide insights into the radiation hazards that would be associated with a human mission to Mars. We report measurements of the radiation dose, dose equivalent, and linear energy transfer spectra. The dose equivalent for even the shortest round-trip with current propulsion systems and comparable shielding is found to be 0.66 ± 0.12 sievert.
Computation of the ionization and radiation dose in arbitrary (exo‐) planetary atmospheres due to energetic particles is recently becoming more important due to several reasons that are either ...correlated with the detection of trace gases for life on exoplanets or with computing dose rates at arbitrary altitudes in the Earth atmosphere. We previously presented Atmospheric Radiation Interaction Simulator, a new Geant4‐based code tailored specifically to enable parametric studies of radiation propagation through exoplanetary atmospheres (Banjac et al., 2019 https://doi.org/10.1029/2018JA026042). Therein, the calculation of ion‐electron pair production rates, which are a mandatory input for chemical and atmospheric modeling, has been presented and validated against Earth measurements and also other, similar, but solar‐system‐specific Geant4‐based codes (PLANETOCOSMICS). In addition to providing input for atmospheric modeling of exoplanets, with AtRIS we aim to directly characterize the habitability by calculating the absorbed dose. In this technical validation study, after showing a detailed analysis of the secondary particles contributing to the atmospheric radiation, we describe a feature of the code which makes direct parametric studies of the interrelation of incident radiation and the resulting absorbed dose throughout the atmosphere possible. In a validation case study configured using an atmospheric model obtained with NRLMSISE‐00 and a primary proton and helium GCR flux calculated using a recent improvement of the force‐field approach, we have compared simulation results with measurements obtained with the Flight Radiation Environment Detector (FRED). We show that Atmospheric Radiation Interaction Simulator (AtRIS) can reproduce the measured dose rate dependence on altitude.
Key Points
Atmospheric Radiation Interaction Simulator AtRIS, a new Geant4‐based code, has been designed to calculate absorbed and equivalent dose rate in a water phantom
A detailed investigation of the secondary particle populations and their contribution to the absorbed dose and dose equivalent is presented
We show that our simulation results are in good agreement with measurements made on a stratospheric balloon
From primates to bees, social status regulates reproduction. In the cichlid fish Astatotilapia (Haplochromis) burtoni, subordinate males have reduced fertility and must become dominant to reproduce. ...This increase in sexual capacity is orchestrated by neurons in the preoptic area, which enlarge in response to dominance and increase expression of gonadotropin-releasing hormone 1 (GnRH1), a peptide critical for reproduction. Using a novel behavioral paradigm, we show for the first time that subordinate males can become dominant within minutes of an opportunity to do so, displaying dramatic changes in body coloration and behavior. We also found that social opportunity induced expression of the immediate-early gene egr-1 in the anterior preoptic area, peaking in regions with high densities of GnRH1 neurons, and not in brain regions that express the related peptides GnRH2 and GnRH3. This genomic response did not occur in stable subordinate or stable dominant males even though stable dominants, like ascending males, displayed dominance behaviors. Moreover, egr-1 in the optic tectum and the cerebellum was similarly induced in all experimental groups, showing that egr-1 induction in the anterior preoptic area of ascending males was specific to this brain region. Because egr-1 codes for a transcription factor important in neural plasticity, induction of egr-1 in the anterior preoptic area by social opportunity could be an early trigger in the molecular cascade that culminates in enhanced fertility and other long-term physiological changes associated with dominance.
The Radiation Assessment Detector (RAD) on the Mars Science Laboratory (MSL) is an energetic particle detector designed to measure a broad spectrum of energetic particle radiation. It will make the ...first-ever direct radiation measurements on the surface of Mars, detecting galactic cosmic rays, solar energetic particles, secondary neutrons, and other secondary particles created both in the atmosphere and in the Martian regolith. The radiation environment on Mars, both past and present, may have implications for habitability and the ability to sustain life. Radiation exposure is also a major concern for future human missions. The RAD instrument combines charged- and neutral-particle detection capability over a wide dynamic range in a compact, low-mass, low-power instrument. These capabilities are required in order to measure all the important components of the radiation environment.
RAD consists of the RAD Sensor Head (RSH) and the RAD Electronics Box (REB) integrated together in a small, compact volume. The RSH contains a solid-state detector telescope with three silicon PIN diodes for charged particle detection, a thallium doped Cesium Iodide scintillator, plastic scintillators for neutron detection and anti-coincidence shielding, and the front-end electronics. The REB contains three circuit boards, one with a novel mixed-signal ASIC for processing analog signals and an associated control FPGA, another with a second FPGA to communicate with the rover and perform onboard analysis of science data, and a third board with power supplies and power cycling or “sleep”-control electronics. The latter enables autonomous operation, independent of commands from the rover. RAD is a highly capable and highly configurable instrument that paves the way for future compact energetic particle detectors in space.
Endoscopic therapy is the first-line treatment of choice for control of acute variceal bleeding (AVB). In high-risk patients with persistent AVB despite pharmacological treatment and endoscopic ...intervention, percutaneous transjugular intrahepatic portosystemic shunting (TIPS) provides a minimally invasive salvage method to reduce portal pressure and control bleeding.
To evaluate factors influencing in-hospital mortality after salvage TIPS (sTIPS) in patients with exsanguinating variceal bleeding despite medical treatment and endoscopic intervention.
Clinical and laboratory data were analysed in all patients treated with sTIPS following failed endoscopic therapy for AVB between August 1991 and November 2020. Factors associated with and predictors of death were determined using bivariate analysis and univariate logistic regression analysis.
Thirty-four patients (29 men, 5 women), mean age 52 years (range 31 - 80), received sTIPS for uncontrolled (n=11) or refractory (n=23) AVB. The causes of portal hypertension were alcohol-related (n=24) and non-alcohol-related cirrhosis. Salvage TIPS controlled bleeding in 32 patients, with recurrence in 1. Ten patients died in hospital (mean 4.8 days, range 1 - 10) of liver failure (n=4), multiorgan failure (n=3), alcoholic cardiomyopathy (n=2) and uncontrolled gastric variceal bleeding (n=1). On bivariate analysis, factors associated with death were Child-Pugh (C-P) score ≥10 (p=0.006), sodium Model for End-stage Liver Disease (MELD-Na) score ≥22 (p<0.001), ≥8 units of blood transfused (p<0.001), Sengstaken-Blakemore balloon tube placement (p<0.001), endotracheal intubation (p<0.001), inotropic support (p<0.001) and endoscopically uncontrolled bleeding (p<0.001). Univariate logistic regression analysis showed that the most significant predictors of mortality were inotrope dependency (odds ratio (OR) 134; p<0.001), endotracheal intubation (OR 99; p<0.001), endoscopically uncontrolled bleeding (OR 28; p=0.001), grade 3 ascites (OR 20.9; p=0.012) and C-P grade C (OR 8.8; p=0.011).
Salvage TIPS controlled variceal bleeding in 94% of patients after failed endoscopic therapy with 29% in-hospital mortality. The most significant predictors of mortality were C-P grade C, grade 3 ascites, inotrope requirement, endotracheal intubation and endoscopically uncontrolled bleeding.
The 10–12 September Solar Energetic Particle event produced the strongest increase of the radiation environment measured by the Radiation Assessment Detector on the surface of Mars since landing in ...August 2012. We report the details of the measurements of the energetic particle environment from Radiation Assessment Detector in Gale crater during this event. The Solar Energetic Particle event increased the low‐energy proton flux (below 100 MeV) by a factor of 30, and the higher‐energy proton flux by a factor of 4, above preevent levels. The 4He flux (below 100 MeV/nuc) rose by factors up to 10, and neutral particles by a factor of 2 above background. The increase started on 10 September around 19:50 UTC, peak‐level fluxes were reached on the morning of 11 September and prevailed for about 10 hr before decreasing toward background levels. The onset of a Forbush decrease on 13 September decreased the proton flux below preevent intensities.
Plain Language Summary
On 10 September 2017, increased solar activity produced a solar energetic particle (SEP)event. This SEP event arrived at Mars around UTC 20:00 the same day in form of energetic particles accelerated to high enough energies to reach the Martian surface. We report here measurements of the energetic particle environment during the event in Gale crater on Mars, made with the Radiation Assessment Detector on board NASA's Curiosity rover. The SEPs increased the Martian surface proton flux below 100‐MeV energy by a factor of 30, and by a factor of 4 at higher energies. The neutral particle environment doubled during the event, which is of particular interest for the planning of solar storm shelters, as the shielding is less effective against neutrons as it is against charged particles. The increase in proton flux was the highest so far observed by Radiation Assessment Detector since landing on Mars in August 2012. However, stronger SEP events are possible that can increase the Martian radiation environment by orders of magnitude more. This makes monitoring the effect of SEPs crucial as radiation remains one of the major health risks for astronauts on exploration missions.
Key Points
On 11 September 2017, RAD observed the strongest solar particle event on the Martian surface since landing
Proton fluxes at the Martian surface increased by factors of up to 30, helium fluxes by factors up to 10
Doubling of neutral particle counts is important for planning of future storm shelter shielding, which is not as effective against neutrons
BACKGROUND: Endoscopic therapy is the first-line treatment of choice for control of acute variceal bleeding (AVB). In high-risk patients with persistent AVB despite pharmacological treatment and ...endoscopic intervention, percutaneous transjugular intrahepatic portosystemic shunting (TIPS) provides a minimally invasive salvage method to reduce portal pressure and control bleeding OBJECTIVES: To evaluate factors influencing in-hospital mortality after salvage TIPS (sTIPS) in patients with exsanguinating variceal bleeding despite medical treatment and endoscopic intervention METHODS: Clinical and laboratory data were analysed in all patients treated with sTIPS following failed endoscopic therapy for AVB between August 1991 and November 2020. Factors associated with and predictors of death were determined using bivariate analysis and univariate logistic regression analysis RESULTS: Thirty-four patients (29 men, 5 women), mean age 52 years (range 31 - 80), received sTIPS for uncontrolled (n=11) or refractory (n=23) AVB. The causes of portal hypertension were alcohol-related (n=24) and non-alcohol-related cirrhosis. Salvage TIPS controlled bleeding in 32 patients, with recurrence in 1. Ten patients died in hospital (mean 4.8 days, range 1 - 10) of liver failure (n=4), multiorgan failure (n=3), alcoholic cardiomyopathy (n=2) and uncontrolled gastric variceal bleeding (n=1). On bivariate analysis, factors associated with death were Child-Pugh (C-P) score >10 (p=0.006), sodium Model for End-stage Liver Disease (MELD-Na) score >22 (p<0.001), > 8 units of blood transfused (p<0.001), Sengstaken-Blakemore balloon tube placement (p<0.001), endotracheal intubation (p<0.001), inotropic support (p<0.001) and endoscopically uncontrolled bleeding (p<0.001). Univariate logistic regression analysis showed that the most significant predictors of mortality were inotrope dependency (odds ratio (OR) 134; p<0.001), endotracheal intubation (OR 99; p<0.001), endoscopically uncontrolled bleeding (OR 28; p=0.001), grade 3 ascites (OR 20.9; p=0.012) and C-P grade C (OR 8.8; p=0.011 CONCLUSION: Salvage TIPS controlled variceal bleeding in 94% of patients after failed endoscopic therapy with 29% in-hospital mortality. The most significant predictors of mortality were C-P grade C, grade 3 ascites, inotrope requirement, endotracheal intubation and endoscopically uncontrolled bleeding
The Radiation Assessment Detector (RAD), onboard the Mars Science Laboratory (MSL) rover Curiosity, measures the energetic charged and neutral particles and the radiation dose rate on the surface of ...Mars. An important factor for determining the biological impact of the Martian surface radiation is the specific contribution of neutrons, with their deeper penetration depth and ensuing high biological effectiveness. This is very difficult to measure quantitatively, resulting in considerable uncertainties in the total radiation dose. In contrast to charged particles, neutral particles (neutrons and gamma rays) are generally only measured indirectly. Measured spectra are a complex convolution of the incident particle spectrum with the detector response function and must be unfolded. We apply an inversion method (based on a maximum likelihood estimation) to calculate the neutron and gamma spectra from the RAD neutral particle measurements. Here we show the first spectra on the surface of Mars and compare them to theoretical predictions. The measured neutron spectrum (ranging from 8 to 740 MeV) translates into a radiation dose rate of 14±4μGy/d and a dose equivalent rate of 61±15μSv/d. This corresponds to 7% of the measured total surface dose rate and 10% of the biologically relevant surface dose equivalent rate on Mars. Measuring the Martian neutron and gamma spectra is an essential step for determining the mutagenic influences to past or present life at or beneath the Martian surface as well as the radiation hazard for future human exploration, including the shielding design of a potential habitat.
Key Points
We calculated the Martian neutron and gamma spectra
We compare the results to Planetocosmics simulations
We calculate dose and dose equivalent rate for the neutron spectrum
The nominal radiation environment in low Earth orbit, especially for the International Space Station (ISS), is dominated by two sources. The first is galactic cosmic radiation, which is modulated by ...the interplanetary and the Earth's magnetic fields, and the second is trapped radiation in the form of the Van Allen belts. The trapped radiation inside the ISS is mostly due to protons of the inner radiation belt. In addition to these sources sporadic solar particle events (SPEs) can produce high doses inside and outside the ISS, depending on the intensity and energy spectrum of the event. Before 2017, the last SPE observed inside the ISS with relevant radiation detectors occurred in May 2012. Even though we are currently approaching the next solar minimum, an SPE was observed in September 2017, which was (a) a ground‐level enhancement, (b) measured with various radiation detector systems onboard the ISS, and (c) observed on the surface of Mars. This paper gives an overview of the 10 September 2017 SPE measured with the DOSIS 3D‐DOSTEL and the ISS‐RAD (Radiation Assessment Detector) instruments, both located at this time in close proximity to each other in the Columbus Laboratory of the ISS. The additional dose received during the SPE was 146.2 μGy in Si as measured by ISS‐RAD and 67.8 μGy in Si as measured by the DOSIS 3D‐DOSTEL instruments. In comparison, the dose measured on the surface of Mars with the Mars Science Laboratory‐RAD instrument accounted to 418 μGy in Si.
Plain Language Summary
Severe solar particle events can be the source for deterministic radiation effects on humans, commonly summarized under the term “radiation sickness.” We examine the evolution of the solar particle event from 10 September 2017, which was the first event since May 2012 seen inside the International Space Station. Radiation dose values are provided by two instruments (DOSIS 3D‐DOSTEL and ISS‐RAD) positioned in close proximity to each other in the Columbus Laboratory.
Key Points
A solar particle event—also seen as GLE 72 on Earth—was measured in September 2017 inside the International Space Station
Data were provided by two detector systems, DOSIS 3D‐DOSTEL and ISS‐RAD, both in close proximity to each other in the Columbus Laboratory
The additional absorbed dose due to the 10 September 2017 solar particle event was in the range of 67.8 to 146.2 μGy in Si
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