1,109 research outputs found
Giant field enhancement in high-index dielectric subwavelength particles
Besides purely academic interest, giant field enhancement within
subwavelength particles at light scattering of a plane electromagnetic wave is
important for numerous applications ranging from telecommunications to medicine
and biology. In this paper, we experimentally demonstrate the enhancement of
the intensity of the magnetic field in a high-index dielectric cylinder at the
proximity of the dipolar Mie resonances by more than two orders of magnitude
for both the TE and TM polarizations of the incident wave. We present a
complete theoretical explanation of the effect and show that the phenomenon is
very general - it should be observed for any high-index particles. The results
explain the huge enhancement of nonlinear effects observed recently in optics,
suggesting a new landscape for all-dielectric nonlinear nanoscale photonics.Comment: 8 pages, 4 figure
Ichthyo-parasitological Characteristic of Lake Vokhtozero Roach
The article presents the results of ichthyo-parasitological studies of roach Lake Vokhtozero in the area of economic activity of the cage farm OOO Raduzhnaya forel (rainbow trout). It is shown that the age structure of the roach population is represented by fish aged 3+ to 10+ years. It is based on sexually mature individuals of middle age: 4+ (25%), 5+ (31%) and 6+ (21%). Of these, 61% are females and 39% are males. Roach is infected with parasites of 14 species belonging to five systematic groups: Myxosporea - 5 species, Trematoda - 5, Ciliophora - 2, Nematoda - 1 and Monogenea - 1. The most common ones are mixosporidia and trematodes. The parasitofauna of roach corresponds to a wide spectrum of nutrition of this species with a predominance of benthic herbivorous type in older individuals
Relation between size of mixing zone and intermediate concentration in miscible displacement
We investigate the miscible displacement of a viscous liquid by a less
viscous one in a porous medium, which frequently leads to the formation of a
mixing zone characterized by thin fingers. The mixing zone grows in time due to
the difference in speed between the leading and trailing edges. The transverse
flow equilibrium (TFE) model provides estimates of these speeds. We propose an
enhancement for the TFE estimates. It is based on the assumption that an
intermediate concentration exists near the tip of the finger, which allows to
reduce the integration interval in the speed estimate. Numerical simulations of
the computational fluid dynamics model were conducted to validate the new
estimates. The refined estimates offer greater accuracy than those provided by
the original TFE model.Comment: 16 pages, 11 figure
Anatomy of the band structure of the newest apparent near-ambient superconductor LuHN
Recently it was claimed that nitrogen-doped lutetium hydride exhibited a
near-ambient superconducting transition with a temperature of 294 K at a
pressure of only 10 kbar, this pressure being several orders of magnitude lower
than previously demonstrated for hydrides under pressure. In this paper, we
investigate within DFT+U the electronic structure of both parent lutetium
hydride LuH and nitrogen doped lutetium hydride LuHN. We
calculated corresponding bands, density of states and Fermi surfaces. It is
shown that in the stoichiometric system the Lu-5d states cross the Fermi level
while the H-1s states make almost no contribution at the Fermi level. However,
with nitrogen doping, the N-2p states enter the Fermi level in large quantities
and bring together a significant contribution from the H-1s states. The
presence of N-2p and H-1s states at the Fermi level in a doped compound can
facilitate the emergence of superconductivity. For instance, nitrogen doping
almost doubles the value of DOS at the Fermi level. Simple BCS analysis shows
that the nitrogen doping of LuH can provide T more than 100K and even
increase it with further hole doping.Comment: 7 pages, 5 figure
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Statistical Properties and Predictability of Extreme Epileptic Events
The use of extreme events theory for the analysis of spontaneous epileptic brain activity is a relevant multidisciplinary problem. It allows deeper understanding of pathological brain functioning and unraveling mechanisms underlying the epileptic seizure emergence along with its predictability. The latter is a desired goal in epileptology which might open the way for new therapies to control and prevent epileptic attacks. With this goal in mind, we applied the extreme event theory for studying statistical properties of electroencephalographic (EEG) recordings of WAG/Rij rats with genetic predisposition to absence epilepsy. Our approach allowed us to reveal extreme events inherent in this pathological spiking activity, highly pronounced in a particular frequency range. The return interval analysis showed that the epileptic seizures exhibit a highly-structural behavior during the active phase of the spiking activity. Obtained results evidenced a possibility for early (up to 7 s) prediction of epileptic seizures based on consideration of EEG statistical properties
Cerebral venous circulatory disturbance as an informative prognostic marker for neonatal hemorrhagic stroke
Neonatal hemorrhagic stroke (NHS) is a major problem of future generation’s health due to the high rate of death and cognitive disability of newborns after NHS. The incidence of NHS in neonates cannot be predicted by standard diagnostic methods. Therefore, the identification of prognostic markers of NHS is crucial. There is evidence that stress-related alterations of cerebral blood flow (CBF) may contribute to NHS. Here, we assessed the stroke-associated CBF abnormalities for high prognosis of NHS using a new model of NHS induced by sound stress in the pre- and post-stroke state. With this aim, we used interdisciplinary methods such as a histological assay of brain tissues, laser speckle contrast imaging and Doppler coherent tomography to monitor cerebral circulation. Our results suggest that the venous stasis with such symptoms as progressive relaxation of cerebral veins, decrease the velocity of blood flow in them are prognostic markers for a risk of NHS and are an informative platform for a future study of corrections of cerebral venous circulatory disturbance related to NHS
Stress plays provoking role in hypertension-related stroke: Injuries of blood-brain barrier function
Chronic hypertension itself does not cause stroke but significantly decreases the resistant to stroke induced by stress due to exhausting of adaptive capacity of cerebral endothelium and decrease resistance of blood-brain barrier to stress
The stress and vascular catastrophes in newborn rats: mechanisms preceding and accompanying the brain hemorrhages
In this study, we analyzed the time-depended scenario of stress response cascade preceding and accompanying brain hemorrhages in newborn rats using an interdisciplinary approach based on: a morphological analysis of brain tissues, coherent-domain optical technologies for visualization of the cerebral blood flow, monitoring of the cerebral oxygenation and the deformability of red blood cells (RBCs). Using a model of stress-induced brain hemorrhages (sound stress, 120 dB, 370 Hz), we studied changes in neonatal brain 2, 4, 6, 8 h after stress (the pre-hemorrhage, latent period) and 24 h after stress (the post-hemorrhage period). We found that latent period of brain hemorrhages is accompanied by gradual pathological changes in systemic, metabolic, and cellular levels of stress. The incidence of brain hemorrhages is characterized by a progression of these changes and the irreversible cell death in the brain areas involved in higher mental functions. These processes are realized via a time-depended reduction of cerebral venous blood flow and oxygenation that was accompanied by an increase in RBCs deformability. The significant depletion of the molecular layer of the prefrontal cortex and the pyramidal neurons, which are crucial for associative learning and attention, is developed as a consequence of homeostasis imbalance. Thus, stress-induced processes preceding and accompanying brain hemorrhages in neonatal period contribute to serious injuries of the brain blood circulation, cerebral metabolic activity and structural elements of cognitive function. These results are an informative platform for further studies of mechanisms underlying stress-induced brain hemorrhages during the first days of life that will improve the future generation's health
A Novel Method to Stimulate Lymphatic Clearance of Beta-Amyloid from Mouse Brain Using Noninvasive Music-Induced Opening of the Blood–Brain Barrier with EEG Markers
The lymphatic system of the brain meninges and head plays a crucial role in the clearance of amyloid-β protein (Aβ), a peptide thought to be pathogenic in Alzheimer’s disease (AD), from the brain. The development of methods to modulate lymphatic clearance of Aβ from the brain coild be a revolutionary step in the therapy of AD. The opening of the blood–brain barrier (OBBB) by focused ultrasound is considered as a possible tool for stimulation of clearance of Aβ from the brain of humans and animals. Here, we propose an alternative method of noninvasive music-induced OBBB that is accompanied by the activation of clearance of fluorescent Aβ (Fαβ) from the mouse brain. Using confocal imaging, fluorescence microscopy, and magnetic resonance tomography, we clearly demonstrate that OBBB by music stimulates the movement of Fαβ and Omniscan in the cerebrospinal fluid and lymphatic clearance of Fαβ from the brain. We propose the extended detrended fluctuation analysis (EDFA) as a promising method for the identification of OBBB markers in the electroencephalographic (EEG) patterns. These pilot results suggest that music-induced OBBB and the EDFA analysis of EEG can be a noninvasive, low-cost, labeling-free, clinical perspective and completely new approach for the treatment and monitoring of AD.Peer Reviewe
Measurement of differential cross sections for top quark pair production using the lepton plus jets final state in proton-proton collisions at 13 TeV
National Science Foundation (U.S.
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