On their way through the heliosphere, galactic cosmic rays (GCRs) are modulated by various effects before they can be detected at Earth. This process can be described by the Parker equation, which ...calculates the phase space distribution of GCRs depending on the main modulation processes: convection, drifts, diffusion, and adiabatic energy changes. A first‐order approximation of this equation is the force field approach, reducing it to a one‐parameter dependency, the solar modulation potential ϕ. Utilizing this approach, it is possible to reconstruct ϕ from ground‐based and spacecraft measurements. However, it has been shown previously that ϕ depends not only on the local interstellar spectrum (LIS) but also on the energy range of interest. We have investigated this energy dependence further, using published proton intensity spectra obtained by PAMELA and heavier nuclei measurements from IMP‐8 and ACE/CRIS. Our results show severe limitations at lower energies including a strong dependence on the solar magnetic epoch. Based on these findings, we will outline a new tool to describe GCR proton spectra in the energy range from a few hundred MeV to tens of GeV over the last solar cycles. In order to show the importance of our modification, we calculate the global production rates of the cosmogenic radionuclide 10Be which is a proxy for the solar activity ranging back thousands of years.
Key Points
We demonstrate significant rigidity dependence of force field approach
We introduce two‐parameter modification as simple and sufficient work‐around
We provide rigidity‐dependent solar modulation potential for 1973‐2016
Can human listeners use implicit temporal contingencies in auditory input to form temporal predictions, and if so, how are these predictions represented endogenously? To assess this question, we ...implicitly manipulated temporal predictability in an auditory pitch discrimination task: unbeknownst to participants, the pitch of the standard tone could either be deterministically predictive of the temporal onset of the target tone, or convey no predictive information. Predictive and non-predictive conditions were presented interleaved in one stream, and separated by variable inter-stimulus intervals such that there was no dominant stimulus rhythm throughout. Even though participants were unaware of the implicit temporal contingencies, pitch discrimination sensitivity (the slope of the psychometric function) increased when the onset of the target tone was predictable in time (N = 49, 28 female, 21 male). Concurrently recorded EEG data (N = 24) revealed that standard tones that conveyed temporal predictions evoked a more negative N1 component than non-predictive standards. We observed no significant differences in oscillatory power or phase coherence between conditions during the foreperiod. Importantly, the phase angle of delta oscillations (1–3 Hz) in auditory areas in the post-standard and pre-target time windows predicted behavioral pitch discrimination sensitivity. This suggests that temporal predictions are encoded in delta oscillatory phase during the foreperiod interval. In sum, we show that auditory perception benefits from implicit temporal contingencies, and provide evidence for a role of slow neural oscillations in the endogenous representation of temporal predictions, in absence of exogenously driven entrainment to rhythmic input.
People with lipedema or Dercum's disease (DD) can have a similar distribution of excess painful nodular subcutaneous adipose tissue (SAT), making them difficult to differentiate.
Case series of 94 ...patients with DD, 160 with lipedema and 18 with both diagnoses (Lip+DD) from a single clinic in an academic medical center to improve identification and differentiation of these disorders by comparison of clinical findings, prevalence of type 2 diabetes (DM2), hypermobility by the Beighton score and assessment of a marker of inflammation, Total complement activity (CH50).
Differences between groups were by Student's t-test with α of 0.05. The Lipedema Group had significantly greater weight, body mass index (BMI), gynoid distributed nodular SAT and fibrotic and heavy tissue than the DD Group. Hypermobility was significantly higher in the Lipedema (58±0.5%) than DD Group (23±0.4%; P<0.0001). DM2 was significantly greater in the DD (16±0.2%; P=0.0007) than the Lipedema Group (6±0.2%). Average pain by an analog scale was significantly higher in the DD (6±2.5%) than the Lipedema Group (4±2.1%; P<0.0001). Fatigue and swelling were common in both groups. Easy bruising was more common in the Lipedema Group, whereas abdominal pain, shortness of breath, fibromyalgia, migraines and lipomas were more prevalent in the DD Group. The percentage of patients with elevated CH50 was significantly positive in both groups.
The significantly lower prevalence of DM2 in people with lipedema compared with DD may be due to the greater amount of gynoid fat known to be protective against metabolic disorders. The high percentage of hypermobility in lipedema patients indicates that it may be a comorbid condition. The location of fat, high average daily pain, presence of lipomas and comorbid painful disorders in DD patients may help differentiate from lipedema.
The threat that solar storms pose to our ever‐modernizing society has gathered significant interest in the recent past. This is partly due to the discoveries of large peaks in the content of ...cosmogenic radionuclides such as radiocarbon (14C) in tree rings and beryllium‐10 (10Be) and chlorine‐36 (36Cl) in ice cores that were linked to extreme solar storms dated to the past millennia. To better assess the threat that they represent, we need to better quantify the relationship between their energy spectrum and their magnitude with respect to the content of the radionuclides that we measure in environmental archives such as ice cores. Here, we model the global production rate that the 59 largest particle storms coming from the Sun have induced for 10Be, 14C, and 36Cl during the past 70 years. We also consider the deposition flux in 10Be and 36Cl over the high latitudes where all Greenland ice cores are located. Our analysis shows that it is unlikely that any recent solar particle event can be detected in 10Be from ice cores. By relating these values to empirical data from ice cores, we are able to quantify different detection limits and uncertainties for 10Be and 36Cl. Due to different sensitivities to solar energetic particles, we assess that 10Be may only be suitable to detect a limited number of extreme solar storms, while 36Cl is suitable to detect any extreme particle event. This implies that the occurrence‐rate estimates of extreme solar storms, based mainly on 14C and 10Be, relate to a small population of potential events.
Plain Language Summary
Solar storms occur when the sun expels charged energetic particles and magnetic material towards Earth. They are a threat to astronauts, spacecraft, and electronic infrastructures on the ground. On rare occasions, solar storms can lead to a significant atmospheric production of radioactive isotopes. If extreme enough, this signal can be retrieved from environmental archives such as ice cores and tree rings. The last known instance of this occurred about a millennium ago. It is therefore paramount to better understand to what extent solar particles can produce these isotopes so that we can, in turn, better identify and quantify the events that generated them. In this study, we combine energy distribution profiles of 59 contemporary solar storms with production functions of the previously mentioned isotopes to model their atmospheric production. This enables us to assess the minimum magnitude of a solar storm required to be detected in ice cores. We also show that one of these isotopes‐chlorine‐36 can be used to detect a considerably wider range of extreme events, relative to the other isotopes. These results have important implications for our current assumptions on the likelihood of an extreme solar storm to hit Earth in the near future.
Key Points
We model the production rate of the radionuclides 10Be, 14C, and, 36Cl by 59 ground level enhancement events
We provide a sensitivity test for ice‐core 10Be and 36Cl produced by extreme solar storms and infer detection limits
36Cl is best to detect past solar storms and its lack of data may lead to an underestimate of the occurrence rate of softer events
The impact of COVID-19 on research Harper, L.; Kalfa, N.; Beckers, G.M.A. ...
Journal of pediatric urology,
10/2020, Letnik:
16, Številka:
5
Journal Article
Rhythmic activity in the delta frequency range (0.5-3 Hz) is a prominent feature of brain dynamics. Here, we examined whether spontaneous delta oscillations, as found in invasive recordings in awake ...animals, can be observed in non-invasive recordings performed in humans with magnetoencephalography (MEG). In humans, delta activity is commonly reported when processing rhythmic sensory inputs, with direct relationships to behaviour. However, rhythmic brain dynamics observed during rhythmic sensory stimulation cannot be interpreted as an endogenous oscillation. To test for endogenous delta oscillations we analysed human MEG data during rest. For comparison, we additionally analysed two conditions in which participants engaged in spontaneous finger tapping and silent counting, arguing that internally rhythmic behaviours could incite an otherwise silent neural oscillator. A novel set of analysis steps allowed us to show narrow spectral peaks in the delta frequency range in rest, and during overt and covert rhythmic activity. Additional analyses in the time domain revealed that only the resting state condition warranted an interpretation of these peaks as endogenously periodic neural dynamics. In sum, this work shows that using advanced signal processing techniques, it is possible to observe endogenous delta oscillations in non-invasive recordings of human brain dynamics.
With Voyager1 crossing the outer boundary of our solar system at the end of 2012, for the first time in the instrumental era an unmodulated local interstellar spectrum (LIS) at galactic particle ...energies below ~500 MeV has been measured. On the basis of these as well as Payload for Antimatter Matter Exploration and Light‐nuclei Astrophysics (PAMELA) and Alpha Magnetic Spectrometer (AMS02) measurements, most recently, three new LIS models have been proposed in the literature. In this study we compare the newest LIS models to previously most often used ones. Thereby, we investigate and discuss the influence of these LIS models on the terrestrial production rates of the cosmogenic radionuclides 10Be and 14C, which are produced due to the interaction of galactic and solar cosmic rays with atmospheric constituents. After being transported within the atmosphere they are preserved in natural archives such as, e.g., ice sheets or tree rings, forming a unique tool to study the solar modulation of thousands of years back in time. To parameterize the heliospheric modulation we apply the force‐field approximation for the individual LIS models from which LIS‐dependent solar modulation parameter (ϕ) values are derived. Furthermore, we present updated sets of linear regression functions containing the opportunity to convert the LIS‐dependent ϕ values between the investigated LIS models. The results are then applied to a long‐term reconstruction of the solar modulation parameter.
Key Points
Comparison of the new LIS models with previously used models
Investigation of the LIS‐dependent differences in the 10Be and 14C production rates
Updated reconstruction of the solar activity over the past 1000 years
The atmospheres of small, potentially rocky exoplanets are expected to cover a diverse range in composition and mass. Studying such objects therefore requires flexible and wide-ranging modeling ...capabilities. We present in this work the essential development steps that lead to our flexible radiative transfer module, REDFOX, and validate REDFOX for the solar system planets Earth, Venus, and Mars, as well as for steam atmospheres. REDFOX is a k-distribution model using the correlated-k approach with the random overlap method for the calculation of opacities used in the δ-two-stream approximation for radiative transfer. Opacity contributions from Rayleigh scattering, UV/visible cross sections, and continua can be added selectively. With the improved capabilities of our new model, we calculate various atmospheric scenarios for K2-18b, a super-Earth/sub-Neptune with ∼8 M⊕ orbiting in the temperate zone around an M star, with recently observed H2O spectral features in the infrared. We model Earth-like, Venus-like, and H2-He primary atmospheres of different solar metallicity and show resulting climates and spectral characteristics compared to observed data. Our results suggest that K2-18b has an H2-He atmosphere with limited amounts of H2O and CH4. Results do not support the possibility of K2-18b having a water reservoir directly exposed to the atmosphere, which would reduce atmospheric scale heights, and with it the amplitudes of spectral features, making the latter inconsistent with the observations. We also performed tests for H2-He atmospheres up to 50 times solar metallicity, all compatible with the observations.
Aims.
The first relativistic solar proton event of solar cycle 25 was detected on 28 October 2021 by neutron monitors (NMs) on the ground and particle detectors on board spacecraft in near-Earth ...space. This is the first ground-level enhancement (GLE) of the current cycle. A detailed reconstruction of the NM response together with the identification of the solar eruption that generated these particles is investigated based on in situ and remote-sensing measurements.
Methods.
In situ proton observations from a few MeV to ∼500 MeV were combined with the detection of a solar flare in soft X-rays, a coronal mass ejection, radio bursts, and extreme ultraviolet (EUV) observations to identify the solar origin of the GLE. Timing analysis was performed, and a relation to the solar sources was outlined.
Results.
GLE73 reached a maximum particle rigidity of ∼2.4 GV and is associated with type III, type II, and type IV radio bursts and an EUV wave. A diversity of time profiles recorded by NMs was observed. This points to the event having an anisotropic nature. The peak flux at
E
> 10 MeV was only ∼30 pfu and remained at this level for several days. The release time of ≥1 GV particles was found to be ∼15:40 UT. GLE73 had a moderately hard rigidity spectrum at very high energies (
γ
∼ 5.5). Comparison of GLE73 to previous GLEs with similar solar drivers is performed.
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