Energy and Flux Measurements of Ultra-High Energy Cosmic Rays Observed During the First ANITA Flight

The first flight of the Antarctic Impulsive Transient Antenna (ANITA) experiment recorded 16 radio signals that were emitted by cosmic-ray induced air showers. For 14 of these events, this radiation was reflected from the ice. The dominant contribution to the radiation from the deflection of positrons and electrons in the geomagnetic field, which is beamed in the direction of motion of the air shower. This radiation is reflected from the ice and subsequently detected by the ANITA experiment at a flight altitude of 36km. In this paper, we estimate the energy of the 14 individual events and find that the mean energy of the cosmic-ray sample is 2.9 EeV. By simulating the ANITA flight, we calculate its exposure for ultra-high energy cosmic rays. We estimate for the first time the cosmic-ray flux derived only from radio observations. In addition, we find that the Monte Carlo simulation of the ANITA data set is in agreement with the total number of observed events and with the properties of those events.Comment: Added more explanation of the experimental setup and textual improvement

The role of visceral and subcutaneous adipose tissue measurements and their ratio by magnetic resonance imaging in subjects with prediabetes, diabetes and healthy controls from a general population without cardiovascular disease.

Objective: To study the relationship of area- and volumetric-based visceral and subcutaneous adipose tissue (VAT and SAT) by MRI and their ratio in subjects with impaired glucose metabolism from the general population.Methods: Subjects from a population-based cohort with established prediabetes, diabetes and healthy controls without prior cardiovascular diseases underwent 3 T MRI. VAT and SAT were assessed as total volume and area on a single slice, and their ratio (VAT/SAT) was calculated. Clinical covariates and cardiovascular risk factors, such as hypertension and glycemic state were assessed in standardized fashion, Univariate and adjusted analyses were conducted.Results: Among 384 subjects (age: 56.2 +/- 9.2 years, 581% male) with complete MRI data available, volumetric and single-slice VAT, SAT and VAT/SAT ratio were strongly correlated (all >r = 0.89), Similarly, VAT/SAT(volum)(e). ratio was strongly correlated with VAT(volume), but not with SAT (r = 0.72 and r = -0.21, respectively). Significant higher levels of VAT, SAT and VAT/SAT ratio were found in subjects with impaired glucose metabolism (all p <= 0.01). After adjustment for potential cardiovascular confounders, VAT(volume) and VAT/SAT(volume) ratio remained significantly higher in subjects with impaired glucose metabolism (VAT(volume) = 6.9 +/- 2.5 I and 3.4 +/- 2.3 I; VAT/SAT(volume) ratio = 0.82 +/- 0.34 I and 0.49 +/- 0,29 I in patients with diabetes and controls, respectively, all p < 0.02), whereas the association for SAT(volume) attenuated. Additionally, there was a decreasing effect of glycemic status on VAT/SAT(volume) ratio with increasing body mass index and waist circumference (p < 0.05).Conclusions: VAT(volume) and VAT/SAT volume ratio are associated with impaired glucose metabolism, independent of cardiovascular risk factors or MRI-based quantification technique, with a decreasing effect of VAT/SAT(volume) ratio in obese subjects.Advances in knowledge: Quantification of VAT(volume) and VAT/SAT(volume). ratio by MRI represents a reproducable biomarker associated with cardiometabolic risk factors in subjects with impaired glucose metabolism, while the association of VAT/SAT(volume) ratio with glycemic state is attenuated in obese subjects

Myocardial tissue characterization by contrast-enhanced cardiac magnetic resonance imaging in subjects with prediabetes, diabetes, and normal controls with preserved ejection fraction from the general population.

Aims To characterize changes in the myocardium in subjects with prediabetes, diabetes, and healthy controls with preserved left ventricular ejection fraction (LVEF) by using cardiac magnetic resonance imaging (CMR) in a sample from the general population.Methods and results Subjects without history of cardiovascular disease and preserved LVEF but established diabetes, prediabetes, and controls from a population-based cohort underwent contrast-enhanced CMR. Obtained parameters included left ventricular (LV) function and morphology, late gadolinium enhancement as well as T1-mapping and derivation of extracellular volume fraction (ECV) by modified Look-Locker inversion recovery for diffuse fibrosis in a subset of patients. Fibrosis volume and cell volume were calculated and LV remodelling index was calculated by dividing the LV mass by its end-diastolic volume. Among 343 subjects (56.1 +/- 9.2 years, 57% males), 47 subjects were classified as diabetes, 78 as prediabetes, and 218 as controls. Haematocrit values and thus ECV parameters were available in 251 subjects. LV remodelling index was significantly higher in participants with prediabetes and diabetes, independent of body mass index (BMI), hypertension, age, and sex. ECV was decreased in subjects with prediabetes and diabetes compared with healthy controls (23.1 +/- 2.4% and 22.8 +/- 3.0%, both P < 0.007). In contrast, cell volume was significantly higher in subjects with prediabetes and diabetes as compared with controls (109.1 +/- 23.8 and 114.9 +/- 32.3 mL vs. 96.5 +/- 26.9 mL, both P < 0.03, respectively). However, differences in ECV and cell volume attenuated after the adjustment for cardiometabolic risk factors, including age, sex, BMI, and hypertension.Conclusion Subjects with prediabetes and diabetes but preserved LVEF had higher LV remodelling indices, suggesting early detectable changes in the disease process, while diffuse myocardial fibrosis appears to be less relevant at this stage

Atmosphere Impact Losses

Determining the origin of volatiles on terrestrial planets and quantifying atmospheric loss during planet formation is crucial for understanding the history and evolution of planetary atmospheres. Using geochemical observations of noble gases and major volatiles we determine what the present day inventory of volatiles tells us about the sources, the accretion process and the early differentiation of the Earth. We further quantify the key volatile loss mechanisms and the atmospheric loss history during Earth’s formation. Volatiles were accreted throughout the Earth’s formation, but Earth’s early accretion history was volatile poor. Although nebular Ne and possible H in the deep mantle might be a fingerprint of this early accretion, most of the mantle does not remember this signature implying that volatile loss occurred during accretion. Present day geochemistry of volatiles shows no evidence of hydrodynamic escape as the isotopic compositions of most volatiles are chondritic. This suggests that atmospheric loss generated by impacts played a major role during Earth’s formation. While many of the volatiles have chondritic isotopic ratios, their relative abundances are certainly not chondritic again suggesting volatile loss tied to impacts. Geochemical evidence of atmospheric loss comes from the He3/22Ne, halogen ratios (e.g., F/Cl) and low H/N ratios. In addition, the geochemical ratios indicate that most of the water could have been delivered prior to the Moon forming impact and that the Moon forming impact did not drive off the ocean. Given the importance of impacts in determining the volatile budget of the Earth we examine the contributions to atmospheric loss from both small and large impacts. We find that atmospheric mass loss due to impacts can be characterized into three different regimes: 1) Giant Impacts, that create a strong shock transversing the whole planet and that can lead to atmospheric loss globally. 2) Large enough impactors (mcap≳2ρ0(πhR)3/2, rcap∼25km for the current Earth), that are able to eject all the atmosphere above the tangent plane of the impact site, where h, R and ρ0 are the atmospheric scale height, radius of the target, and its atmospheric density at the ground. 3) Small impactors (mmin> 4 πρ0h3, rmin∼1km for the current Earth), that are only able to eject a fraction of the atmospheric mass above the tangent plane. We demonstrate that per unit impactor mass, small impactors with rmin< r< rcap are the most efficient impactors in eroding the atmosphere. In fact for the current atmospheric mass of the Earth, they are more than five orders of magnitude more efficient (per unit impactor mass) than giant impacts, implying that atmospheric mass loss must have been common. The enormous atmospheric mass loss efficiency of small impactors is due to the fact that most of their impact energy and momentum is directly available for local mass loss, where as in the giant impact regime a lot of energy and momentum is ’wasted’ by having to create a strong shock that can transverse the entirety of the planet such that global atmospheric loss can be achieved. In the absence of any volatile delivery and outgassing, we show that the population of late impactors inferred from the lunar cratering record containing 0.1% M⊕ is able to erode the entire current Earth’s atmosphere implying that an interplay of erosion, outgassing and volatile delivery is likely responsible for determining the atmospheric mass and composition of the early Earth. Combining geochemical observations with impact models suggest an interesting synergy between small and big impacts, where giant impacts create large magma oceans and small and larger impacts drive the atmospheric loss