Spatially Highly Resolved Solar-wind-induced Magnetic Field on Venus

The current work investigates the Venusian solar-wind-induced magnetosphere at a high spatial resolution using all Venus Express (VEX) magnetic observations through an unbiased statistical method. We first evaluate the predictability of the interplanetary magnetic field (IMF) during VEX’s Venusian magnetospheric transits and then map the induced field in a cylindrical coordinate system under different IMF conditions. Our mapping resolves structures on various scales, ranging from the ionopause to the classical IMF draping. We also resolve two recently reported structures, a low-ionosphere magnetization over the terminator, and a global “looping” structure in the near magnetotail. In contrast to the reported IMF-independent cylindrical magnetic field of both structures, our results illustrate their IMF dependence. In both structures, the cylindrical magnetic component is more intense in the hemisphere with an upward solar wind electric field (E SW) than in the opposite hemisphere. Under downward E SW, the looping structure even breaks, which is attributable to an additional draped magnetic field structure wrapping toward −E SW. In addition, our results suggest that these two structures are spatially separate. The low-ionosphere magnetization occurs in a very narrow region, at about 88°–95° solar zenith angle and 185–210 km altitude. A least-squares fit reveals that this structure is attributable to an antisunward line current with 191.1 A intensity at 179 ± 10 km altitude, developed potentially in a Cowling channel.

Coastal Wave Extremes around the Pacific and Their Remote Seasonal Connection to Climate Modes

At first order, wind-generated ocean surface waves represent the dominant forcing of open-coast morpho-dynamics and associated vulnerability over a wide range of time scales. It is therefore paramount to improve our understanding of the regional coastal wave variability, particularly the occurrence of extremes, and to evaluate how they are connected to large-scale atmospheric regimes. Here, we propose a new “2-ways wave tracking algorithm” to evaluate and quantify the open-ocean origins and associated atmospheric forcing patterns of coastal wave extremes all around the Pacific basin for the 1979–2020 period. Interestingly, the results showed that while extreme coastal events tend to originate mostly from their closest wind-forcing regime, the combined influence from all other remote atmospheric drivers is similar (55% local vs. 45% remote) with, in particular, ~22% coming from waves generated remotely in the opposite hemisphere. We found a strong interconnection between the tropical and extratropical regions with around 30% of coastal extremes in the tropics originating at higher latitudes and vice-versa. This occurs mostly in the boreal summer through the increased seasonal activity of the southern jet-stream and the northern tropical cyclone basins. At interannual timescales, we evidenced alternatingly increased coastal wave extremes between the western and eastern Pacific that emerge from the distinct seasonal influence of ENSO in the Northern and SAM in the Southern Hemisphere on their respective paired wind-wave regimes. Together these results pave the way for a better understanding of the climate connection to wave extremes, which represents the preliminary step toward better regional projections and forecasts of coastal waves.

Cortex: Gross Anatomy

The cerebral cortex consists of 2 hemispheres, the left and the right. These are divided by the falx cerebri, a dural-derived structure. The cerebral cortex receives input from various subcortical structures, often connecting through the thalamus and from other areas of the cortex by association fibers. The cortex then projects back to wide regions of the central nervous system, including the cortex, thalamus, basal nuclei, cerebellum, brainstem, and spinal cord. The types of fibers connecting areas of the central nervous system are designated according to the regions they connect. For instance, the fibers connecting the cortex to subcortical structures are called projection fibers. The fibers connecting 1 hemisphere to the opposite hemisphere are called callosal fibers, and the fibers connecting areas within the same hemisphere are called association fibers. Fibers connecting the cortex to the thalamus are designated corticothalamic fibers.

Paradoxical facilitation alongside interhemispheric inhibition

Neurophysiological experiments using transcranial magnetic stimulation (TMS) have sought to probe the function of the motor division of the corpus callosum. Primary motor cortex sends projections via the corpus callosum with a net inhibitory influence on the homologous region of the opposite hemisphere. Interhemispheric inhibition (IHI) experiments probe this inhibitory pathway. A test stimulus (TS) delivered to the motor cortex in one hemisphere elicits motor evoked potentials (MEPs) in a target muscle, while a conditioning stimulus (CS) applied to the homologous region of the opposite hemisphere modulates the effect of the TS. We predicted that large CS MEPs would be associated with increased IHI since they should be a reliable index of how effectively contralateral motor cortex was stimulated and therefore of the magnitude of interhemispheric inhibition. However, we observed a strong tendency for larger CS MEPs to be associated with reduced interhemispheric inhibition which in the extreme lead to a net effect of facilitation. This surprising effect was large, systematic, and observed in nearly all participants. We outline several hypotheses for mechanisms which may underlie this phenomenon to guide future research.

Effects of tidal heating in Proxima Centauri b's thermal evolution

<p>The recent discovery of a terrestrial planet orbiting Proxima Centauri, our closest neighbor (an M5.5V star of 0.1 M<sub>Sun</sub> mass and only 1.3 pc distance to the Sun), offers an excellent planet laboratory to study the most important theories of planet evolution and composition. The planet (Proxima b) is orbiting the star in its habitable zone at a separation of only ~0.05 AU and an orbital period of ~11 days, and most recent studies suggest a non-zero eccentricity of about 0.17. With a mass of >=1.2 M<sub>Earth</sub>, Proxima b is expected to have a rocky composition, which might resemble the Earth. It is therefore an excellent target to characterize terrestrial planets similar to Earth, avoiding the inherent biases of only studying the terrestrial planets of the solar system.</p> <p>Due to its close orbit and expected eccentricity, Proxima b most likely suffers from severe tidal heating, which can have an extreme incidence in the planet's habitability and the survival of an atmosphere. In this work, we perform a comprehensive analysis of the incidence that different distribution patterns of tidal heating can have on Proxima b's interior and thermal evolution. To accomplish this goal, we consider various possible geometries of the planet, from the simplest case, homogeneous distribution of the generated heat, to the more complicated cases, with an inhomogeneous distribution pattern that depends on the planet's interior structure (a stratified sphere, an incompressible homogeneous planet, or a two-layer structure with a differentiated core). The different models considered alter how tidal heat is distributed throughout the planet's interior, which can highly affect its overall thermal evolution.</p> <p>Furthermore, due to its proximity to the central star, Proxima b may as well be in synchronous rotation with Proxima Centauri. This can cause an extreme surface temperature variation between the hemisphere that permanently faces the star and the opposite hemisphere. In this work, the effect that synchronous rotation may have on Proxima b's interior is also thoroughly investigated.</p>

Impact of Antarctic Sudden Stratospheric Warming on Mid-Latitude Thermosphere and Ionosphere over USA and Europe

<p>Limited observational evidence indicates that ionospheric changes caused by Arctic SSWs propagate to at least the middle latitudes in the Southern Hemisphere. However, it is not known if similar ionospheric anomalies are produced by Antarctic SSWs, mostly because Antarctic SSWs occur less often than the Arctic events. The sudden stratospheric warming of September 2019 has provided a perfect opportunity to investigate whether SSW are linked to upper atmospheric anomalies at middle latitudes of the opposite hemisphere. In this study we provide an overview of thermospheric and ionospheric anomalies observed in September 2019 at middle latitudes in the Northern Hemisphere. Our results indicate persistent and strong positive anomalies in total electron content and thermospheric O/N2 ratio observed in the western region of USA. Central and eastern regions of USA do not experience similar positive perturbations and show mostly moderate suppression of TEC reaching 20-40% of the baseline. Both positive and negative anomalies are observed over the central Europe. We discuss potential mechanisms that could be responsible for the observed features and suggest that regional differences in TEC response could be related to modulation of thermospheric winds by SSW and large declination angle over Western US.</p>

Large-scale asymmetry in galaxy spin directions: evidence from the Southern hemisphere

Recent observations using several different telescopes and sky surveys showed patterns of asymmetry in the distribution of galaxies by their spin directions as observed from Earth. These studies were done with data imaged from the Northern hemisphere, showing excellent agreement between different telescopes and different analysis methods. Here, data from the DESI Legacy Survey was used. The initial dataset contains $\sim\!2.2\times 10^7$ galaxy images, reduced to $\sim\!8.1\times 10^5$ galaxies annotated by their spin direction using a symmetric algorithm. That makes it not just the first analysis of its kind in which the majority of the galaxies are in the Southern hemisphere, but also by far the largest dataset used for this purpose to date. The results show strong agreement between opposite parts of the sky, such that the asymmetry in one part of the sky is similar to the inverse asymmetry in the corresponding part of the sky in the opposite hemisphere. Fitting the distribution of galaxy spin directions to cosine dependence shows a dipole axis with probability of 4.66 $\sigma$ . Interestingly, the location of the most likely axis is within close proximity to the CMB Cold Spot. The profile of the distribution is nearly identical to the asymmetry profile of the distribution identified in Pan-STARRS, and it is within 1 $\sigma$ difference from the distribution profile in SDSS and HST. All four telescopes show similar large-scale profile of asymmetry.

Neurofunctional Components of Simple Calculation: A Magnetoencephalography Study

Our ability to calculate implies more than the sole retrieval of the correct solution. Essential processes for simple calculation are related to the spreading of activation through arithmetic memory networks. There is behavioral and electrophysiological evidence for these mechanisms. Their brain location is, however, still uncertain. Here, we measured magnetoencephalographic brain activity during the verification of simple multiplication problems. Following the operands, the solutions to verify could be preactivated correct solutions, preactivated table-related incorrect solutions, or unrelated incorrect solutions. Brain source estimation, based on these event-related fields, revealed 3 main brain networks involved in simple calculation: 1) bilateral inferior frontal areas mainly activated in response to correct, matching solutions; 2) a left-lateralized frontoparietal network activated in response to incorrect table-related solutions; and (3) a strikingly similar frontoparietal network in the opposite hemisphere activated in response to unrelated solutions. Directional functional connectivity analyses revealed a bidirectional causal loop between left parietal and frontal areas for table-related solutions, with frontal areas explaining the resolution of arithmetic competition behaviorally. Hence, this study isolated at least 3 neurofunctional networks orchestrated between hemispheres during calculation.

The current state of science on aphasia

We very often come across agraphy as a complication in any form of rupture disorder. This even in some forms of verbal speech is a direct consequence of it. For most people, even for many who have been, the right hand has the ability to write; it, therefore, is located under the influence of the center, which innervates the movements of the right hand. The paralysis of the right hand, in the face of a lesion in the center of the upper limb (the middle third of both central gyri), will, of course, destroy the careful movement necessary for writing. Sometimes, on the other hand, agraphia without the slightest damage to the motor function of the hand is subject to even greater doubt. Even Pitres's remarkable case showed mild motor and sensory disorders. Such disorders, perhaps, are easier to detect on the hands, than similar disorders with local aphasia on the lips, tongue, etc., since there can be corrected in the result of external infiltration from the opposite hemisphere, which is impossible here. But in any case, there is a connection on one side of the r between the normal state of the hand and the ability to write on the other side between agraphia and paralysis of the right hand.

Restorative processes of the vascular bed of the brain in the progressive course of ischemic stroke

The objective is to study morphometry of the restoration processes of the cerebral vascular bed in the progressive course of ischemic stroke. We studied the structure of the vessels and parenchyma of the brain of patients who died of ischemic stroke in the angio-neurological department of the National Hospital under the Ministry of Health of the Kyrgyz Republic. With a progressive course of ischemic stroke, brain vessel lesions are characterized by peculiar changes in the shape and contents of the vessels, different from the vessels surrounding the ischemic area, and tissues of the opposite hemisphere. The study showed that reparative processes appear early and are expressed by a change in the number of capillaries, angiogenesis and recalibration of existing vessels. With a progressive ischemic stroke, dystrophic processes prevail over the compensatory-adaptive reactions of the central nervous system, while the latter are insufficient to restore lost functions.