The interpretation of TIROS radiation data for practical use in synoptic weather analysis

Interpretation of TIROS III radiation data to demonstrate practical applications in synoptic weather analyse

Long-term variations of turbulent transport coefficients in a solar-like convective dynamo simulation

The Sun, aside from its eleven year sunspot cycle is additionally subject to long term variation in its activity. In this work we analyse a solar-like convective dynamo simulation, containing approximately 60 magnetic cycles, exhibiting equatorward propagation of the magnetic field, multiple frequencies, and irregular variability, including a missed cycle and complex parity transitions between dipolar and quadrupolar modes. We compute the turbulent transport coefficients, describing the effects of the turbulent velocity field on the mean magnetic field, using the test-field method. The test-field analysis provides a plausible explanation of the missing cycle in terms of the reduction of $\alpha_{\phi\phi}$ in advance of the reduced surface activity, and enhanced downward turbulent pumping during the event to confine some of the magnetic field at the bottom of the convection zone, where local maximum of magnetic energy is observed during the event. At the same time, however, a quenching of the turbulent magnetic diffusivities is observed, albeit differently distributed in depth compared to the other transport coefficients. Therefore, dedicated mean-field modelling is required for verification.Comment: 11 pages, 12 figures, accepted by AN for 14th Potsdam Thinksho

First semester academic functioning of college students : the role of stressful and traumatic life events.

A large number of the nearly 20 million students who were attending American colleges in 2015 will not graduate. One factor that may affect the success of students is the influence of past experiences, including past adversity, or exposure to traumatic or non-traumatic stressors. The present study sought to better describe and understand the role of stress/trauma history in college students from low socioeconomic backgrounds. The potential relationship this history has with academic outcomes was explored. Additionally, as not all students with a history of stressful and traumatic life events struggle academically, self-reported resilience, as well as resiliency factors, were included in analyses to determine the potential role these variables may have. Self-reported history of stressful/traumatic life events, resilience, and various demographic factors was collected at college orientation for a group of students (N = 54) with low socioeconomic backgrounds (family income below 150% of the poverty level). Academic record information was collected at the end of the first semester. Overall, the present sample was similar to other college students in terms of event exposure (93% total, 57% traumatic), as well as mental health symptoms and self-reported resilience and resiliency factors. Resiliency variables were correlated with one another, but not with event vi exposure or academic outcomes. Total event exposure was significantly correlated with fall course withdrawals, and for each event reported, a student was 24% more likely to withdraw from a course. Exploratory regressions examining event exposure weighted by perceived effect on life predicting fall GPA and fall D/F grades revealed that this accounted for 14% and 11% of the variance, respectively. Including one potential resiliency factor in the regression model did not improve the model in a hierarchical regression. This research has implications for educators, mental health professionals, and college administrators

A Quasi-Global Presentation of TIROS III Radiation Data

The TIROS III meteorological satellite was equipped with a five-channel medium resolution radiometer to measure the reflected solar radiation as well as the infrared emission of the earth-atmosphere system in five different spectral regions (Reference 1). According to the initial design of this radiation experiment, one of the most useful applications of the infrared measurements was to be the derivation of day and nighttime cloudiness from Channel 2, which was sensitive within the atmospheric "window" region (8 to 12 microns). Several authors already have demonstrated and discussed the principal usefulness of these data for this particular purpose (References 2, 3, and 4). This present study was performed to investigate and demonstrate the utility of the TIROS radiation data for global synoptic analyses

Non-random inversion landscapes in prokaryotic genomes are shaped by heterogeneous selection pressures

Inversions are a major contributor to structural genome evolution in prokaryotes. Here, using a novel alignment-based method, we systematically compare 1,651 bacterial and 98 archaeal genomes to show that inversion landscapes are frequently biased toward (symmetric) inversions around the origin–terminus axis. However, symmetric inversion bias is not a universal feature of prokaryotic genome evolution but varies considerably across clades. At the extremes, inversion landscapes in Bacillus–Clostridium and Actinobacteria are dominated by symmetric inversions, while there is little or no systematic bias favoring symmetric rearrangements in archaea with a single origin of replication. Within clades, we find strong but clade-specific relationships between symmetric inversion bias and different features of adaptive genome architecture, including the distance of essential genes to the origin of replication and the preferential localization of genes on the leading strand. We suggest that heterogeneous selection pressures have converged to produce similar patterns of structural genome evolution across prokaryotes

On the standing wave mode of giant pulsations

Both odd-mode and even-mode standing wave structures have been proposed for giant pulsations. Unless a conclusion is drawn on the field-aligned mode structure, little progress can be made in understanding the excitation mechanism of giant pulsations. In order to determine the standing wave mode, we have made a systematic survey of magnetic field data from the AMPTE CCE spacecraft and from ground stations located near the geomagnetic foot point of CCE. We selected time intervals when CCE was close to the magnetic equator and also magnetically close to Syowa and stations in Iceland, and when either transverse or compressional Pc 4 waves were observed at CCE. Magnetograms from the ground stations were then examined to determine if there was a giant pulsation in a given time interval. One giant pulsation was associated with a compressional wave, while no giant pulsation was observed in association with transverse wave events. The CCE magnetic field record for the giant pulsation exhibited a remarkable similarity to a giant pulsation observed from the ATS 6 geostationary satellite near the magnetic equator (Hillebrand et al., 1982). In agreement with Hillebrand et al., we conclude that the compressional nature of the giant pulsation is due to an odd-mode standing wave structure. This conclusion places a strong constraint on the generation mechanism of giant pulsations. In particular, if giant pulsations are excited through the drift bounce resonance of ions with standing Alfvén waves, ω - mωd = ±Nωb, where ω is the wave frequency, m is the azimuthal wave number, ωd is the ion drift frequency,N is an integer, and ωb is the ion bounce frequency, then the resonance must occur at an even N

Stellar X-rays and magnetic activity in 3D MHD coronal models

Observations suggest a power-law relation between the coronal emission in X-rays, $L_{\rm{X}}$, and the total (unsigned) magnetic flux at the stellar surface, $\Phi$. The physics basis for this relation is poorly understood. We use three-dimensional (3D) magnetohydrodynamics (MHD) numerical models of the coronae above active regions, that is, strong concentrations of magnetic field, to investigate the $L_{\rm{X}}$ versus $\Phi$ relation and illustrate this relation with an analytical model based on simple well-established scaling relations. In the 3D MHD model horizontal (convective) motions near the surface induce currents in the coronal magnetic field that are dissipated and heat the plasma. This self-consistently creates a corona with a temperature of 1 MK. We run a series of models that differ in terms of the (unsigned) magnetic flux at the surface by changing the (peak) magnetic field strength while keeping all other parameters fixed. In the 3D MHD models we find that the energy input into the corona, characterized by either the Poynting flux or the total volumetric heating, scales roughly quadratically with the unsigned surface flux $\Phi$. This is expected from heating through field-line braiding. Our central result is the nonlinear scaling of the X-ray emission as $L_{\rm{X}}\propto \Phi^{3.44}$. This scaling is slightly steeper than found in recent observations that give power-law indices of up to only 2 or 3. Assuming that on a real star, not only the peak magnetic field strength in the active regions changes but also their number (or surface filling factor), our results are consistent with observations. Our model provides indications of what causes the steep increase in X-ray luminosity by four orders of magnitude from solar-type activity to fast rotating active stars.Comment: Updated version after review: 15 pages, 12 figures, Accepted for publication in Astronomy and Astrophysic