Depolarization Channel Research Articles

Genetic Insights and Epidemiological Models in Understanding Primary Open Angle Glaucoma

Primary open-angle glaucoma (POAG) is a multifactorial chronic optic neuropathy with significant genetic heterogeneity. The pathogenesis of POAG involves an imbalance between the production and drainage of aqueous humor (AH). Genetic theories suggest that transgenic mice demonstrating the GLU50LYS mutation in optineurin (OPTN) experience retinal ganglion cell apoptosis, while mutant myocilin (MYOC) proteins induce endoplasmic reticulum (ER) stress, leading to an unfolded protein response (UPR) and subsequent apoptosis of trabecular meshwork cells (TMC). Furthermore, the interaction between MYOC and mitochondria in the trabecular meshwork (TM) and astrocytes may lead to mitochondrial membrane depolarization and calcium channel dysregulation, contributing to POAG. Overexpression of MYOC variants (P370L, Q368X) is also implicated, as are epigenetic modifications and signaling pathways such as histone and DNA modification. POAG has been associated with autosomal dominant inheritance, with mutations in MYOC and OPTN being prominent causative factors, although many cases involve multiple genetic loci. Currently, over 20 genetic loci have been linked to POAG, with 14 chromosomal loci (GLC1A to GLC1N) identified, 5 of which contribute to juvenile-onset open-angle glaucoma (JOAG). Of these loci, MYOC, OPTN, WD repeat domain 36 (WDR36), and neurotrophin-4 (NTF4) are the most studied causative genes. The ongoing study of molecular genetics offers potential pathways for future therapeutic advances in the treatment of POAG.

Interior pH-sensing residue of human voltage-gated proton channel Hv1 is histidine 168

The molecular mechanisms governing the human voltage-gated proton channel hHv1 remain elusive. Here, we used membrane-enabled hybrid-solvent continuous constant pH molecular dynamics (CpHMD) simulations with pH replica exchange to further evaluate the structural models of hHv1 in the closed (hyperpolarized) and open (depolarized) states recently obtained with MD simulations and explore potential pH-sensing residues. The CpHMD titration at a set of symmetric pH conditions revealed three residues that can gain or lose protons upon channel depolarization. Among them, residue H168 at the intracellular end of the S3 helix switches from the deprotonated to the protonated state and its protonation is correlated with the increased tilting of the S3 helix during the transition from the closed to the open state. Thus, the simulation data suggest H168 as an interior pH sensor, in support of a recent finding based on electrophysiological experiments of Hv1 mutants. We propose that protonation of H168 acts as a key that unlocks the closed channel configuration by increasing the flexibility of the S2-S3 linker, which increases the tilt angle of S3 and enhances the mobility of the S4 helix, thus promoting channel opening. Our work represents an important step toward deciphering the pH-dependent gating mechanism of hHv1.

Polar Stratospheric Cloud Observations at Concordia Station by Remotely Controlled Lidar Observatory

Polar stratospheric clouds (PSCs) form in polar regions, typically between 15 and 25 km above mean sea level, when the local temperature is sufficiently low. PSCs play an important role in the ozone chemistry and the dehydration and denitrification of the stratosphere. Lidars with a depolarization channel may be used to detect and classify different classes of PSCs. The main PSC classes are water ice, nitric acid trihydrate (NAT), and supercooled ternary solutions (STSs), the latter being liquid droplets consisting of water, nitric acid, and sulfuric acid. PSCs have been observed at the lidar observatory at Concordia Station from 2014 onward. The harsh environmental conditions at Concordia during winter render successful lidar operation difficult. To facilitate the operation of the observatory, several measures have been put in place to achieve an almost complete remote control of the system. PSC occurrence is strongly correlated with local temperatures and is affected by dynamics, as the PSC coverage during the observation season shows. PSC observations in 2021 are shown as an example of the capability and functionality of the lidar observatory. A comparison of the observations with the satellite-borne CALIOP (Cloud-Aerosol Lidar with Orthogonal Polarization) lidar has been made to demonstrate the quality of the data and their representativeness for the Antarctic Plateau.

New indoor propagation model proposed for future B5G/6G rollout

Abstract The rollout of the fifth-generation (5G) mobile network was completed in 2020. Now, the focus shifts towards exploring the new perspectives of Beyond 5G (B5G) and 6G. Despite being a key enabler of 5G, millimeter wave technology has not yet been fully implemented due to various deployment challenges. Over the past decade, numerous efforts have been dedicated to modeling the propagation channel across the spectrum from 0.5 to 100 GHz. Propagation models such as Close-In (CI), Floating Intercept (FI), and single frequency Alpha-Beta-Gamma (ABG) have been extensively utilized. However, a significant deviation between co- and cross-polarization models has been observed in many estimated models in the literature. In this paper, we propose an optimization of the classic CI model by considering both TX and RX antenna heights, along with a correction coefficient. Initially, we estimate the propagation channel using the classic CI model in indoor environments, revealing a notable deviation between co- and cross-polarization models. Subsequently, we introduce a new model aimed at reducing this deviation and optimizing the Path Loss Exponent (PLE). With our proposed model, the estimated channel depolarization in Line-of-Sight (LOS) conditions stands at 2.8 dB, 5.6 dB, and 2.9 dB for room, corridor, and stairwell environments, respectively. In contrast, utilizing the conventional model yields channel depolarization figures of 4.8 dB, 8.2 dB, and 7 dB for the same environments. This disparity in channel depolarization can have significant implications for millimeter wave propagation, particularly during meteorological events such as rainfall.

All–potassium channel CRISPR screening reveals a lysine-specific pathway of insulin secretion

ObjectiveGenome-scale CRISPR–Cas9 knockout coupled with single-cell RNA sequencing (scRNA-seq) has been used to identify function-related genes. However, this method may knock out too many genes, leading to low efficiency in finding genes of interest. Insulin secretion is controlled by several electrophysiological events, including fluxes of KATP depolarization and K+ repolarization. It is well known that glucose stimulates insulin secretion from pancreatic β-cells, mainly via the KATP depolarization channel, but whether other nutrients directly regulate the repolarization K+ channel to promote insulin secretion is unknown. MethodsWe used a system involving CRISPR–Cas9-mediated knockout of all 83 K+ channels and scRNA-seq in a pancreatic β cell line to identify genes associated with insulin secretion. ResultsThe expression levels of insulin genes were significantly increased after all–K+ channel knockout. Furthermore, Kcnb1 and Kcnh6 were the two most important repolarization K+ channels for the increase in high-glucose-dependent insulin secretion that occurred upon application of specific inhibitors of the channels. Kcnh6 currents, but not Kcnb1 currents, were reduced by one of the amino acids, lysine, in both transfected cells, primary cells and mice with β-cell-specific deletion of Kcnh6. ConclusionsOur function-related CRISPR screen with scRNA-seq identifies Kcnh6 as a lysine-specific channel.

Entanglement-enabled decoherence-free transmission of two-color photons through a single mode fiber.

We demonstrate decoherence-tolerant transmission of a Bell state through a single-mode fiber (SMF) using the photon frequency degree of freedom. To this end, a slightly non-degenerate polarization-entangled singlet, |Ψ -⟩=(|HV⟩-|VH⟩)/2, is localized at the SMF as the depolarization channel subject to random noise due to incessant fiber bending. Two-photon beats and quantum state tomography jointly verify the absence of collective decoherence, showing that |Ψ -⟩ is the sought-after one-dimensional decoherence-free subspace (DFS) pertaining to SMF. Efficient splitting and combining of photon streams in our DFS help outperform the DFS in time domain. This motivates us to attempt DFS-enabled fault-tolerant fiber transmission of biphoton qubits. Two-photon BB84 protocol is implemented in a polarization-maintaining fiber to which dephasing noise is relevant so that a two-dimensional DFS is appropriate. A low bit error rate 5.4% is achieved by encoding one-qubit information onto the biphoton state in spite of significant polarization fluctuation. Our scalable frequency-based DFS has a natural affinity for wavelength division multiplexing in fiber communication by design and as such is extensible to multi-particle entanglement.

Analysis Of Differentially Expressed Genes By RNA-Sequencing In 38 Cases of Rasmussen Encephalitis: New Insights on Non-Inflammatory Pathways (P12-9.002)

<h3>Objective:</h3> To analyze aberrant gene expression pathways involved in the pathophysiology of Rasmussen Encephalitis (RE) in a large cohort of brain specimens from affected children. <h3>Background:</h3> RE is a rare cause of pharmacoresistant epilepsy, characterized by progressive hemispheric inflammation resulting in seizures and, if left untreated, hemiplegia, hemianopia and cognitive decline. Data on gene expression in this condition are lacking. <h3>Design/Methods:</h3> We conducted RNA-sequencing of flash-frozen resected epileptogenic tissue from 38 children with RE. Control brain tissue included 10 brain specimens from perilesional resected areas in different patients with focal cortical dysplasia. RNA-sequencing was performed using standard protocol on Illumina HiSeq 2x150bp sequencing, single index platform with polyA selection library prep. After extraction of normalized gene hit counts, we utilized the <i>DESeq2</i> package with R version 4.2.1. The Wald test was used to generate p-values and log2 fold changes. Genes with an adjusted p-value &lt; 0.05 were called as differentially expressed genes (DEG) for each comparison. Gene enrichment analysis was then performed with the Reactome platform. <h3>Results:</h3> We identified 6184 upregulated and 3789 downregulated genes in RE vs. controls. Functional gene clustering analysis showed overrepresentation of several pathways involved in neuroinflammation including interferon alpha/beta (p=7.77E-11) and gamma (p=1.17E-12) signaling, IL-4/IL-13 (p=1.15E-2), IL-10 (p=2.18E-2) signaling, class I MHC-mediated antigen processing (p=4.22E-5), and non-inflammatory pathways such as nonsense-mediated RNA decay (p=2.04E-3), translation elongation cycle (p=5.42E-4). We observed downregulation of multiple neuronal pathways: neurotransmitter receptors and postsynaptic signal transmission (p=3.79E-7), activation of NMDA receptors (p=1.72E-5), GABA receptor activation (p=3.19E-2), glutamate binding (p=2.1E-2), presynaptic depolarization and Ca channel opening (p=1.49E-2). Extra-neuronal downregulated genes included: transcriptional regulation of MECP2 (p=4.49E-4), L1CAM interactions (p=1.51E-3), signaling by NTRKs (p=3.93E-2), calmodulin pathway (p=2.05E-1). <h3>Conclusions:</h3> With this study, we contribute to expanding the knowledge of pathophysiological inflammatory and non-inflammatory processes involved in Rasmussen’s encephalitis. <b>Disclosure:</b> Dr. Bartolini has received personal compensation in the range of $10,000-$49,999 for serving as an Editor, Associate Editor, or Editorial Advisory Board Member for American Academy of Neurology. The institution of Dr. Chan has received research support from TSC Alliance. Ms. Lob has nothing to disclose. Ms. Wu has nothing to disclose. Dr. Uzun has nothing to disclose. Dr. Oluigbo has nothing to disclose. The institution of Dr. Gaillard has received research support from all federal or foundation grants, NINDS, NIDCD, NICHD, NSF ,PERF. Dr. Chang has nothing to disclose. Gary W. Mathern has nothing to disclose. The institution of Dr. Liu has received research support from NIH/NINDS.

Entanglement dynamics of noisy random circuits

The process by which open quantum systems thermalize with an environment is both of fundamental interest and relevant to noisy quantum devices. As a minimal model of this process, we consider a qudit chain evolving under local random unitaries and local depolarization channels. After mapping to a statistical mechanics model, the depolarization (noise) acts like a symmetry-breaking field, and we argue that it causes the system to thermalize within a timescale independent of system size. We show that various bipartite entanglement measures---mutual information, operator entanglement, and entanglement negativity---grow at a speed proportional to the size of the bipartition boundary. As a result, these entanglement measures obey an area law: Their maximal value during the dynamics is bounded by the boundary instead of the volume. In contrast, if the depolarization only acts at the system boundary, then the maximum value of the entanglement measures obeys a volume law. We complement our analysis with scalable simulations involving Clifford gates, for both one- and two-dimensional systems.

UAV-Correlated MIMO Channels: 3-D Geometrical-Based Polarized Model and Capacity Analysis

The unmanned aerial vehicle (UAV) communication with the multiple-input–multiple-output (MIMO) system has attracted lots of attention to improve spectral efficiency and channel capacity. The large antenna spacing is often required to reduce the spatial correlation between subchannels. However, this requirement cannot be well satisfied in practical scenarios due to the limited dimension of UAV platforms. Therefore, polarization diversity is a promising approach for UAV MIMO systems. In this work, we propose a three-dimensional (3-D) geometrical-based polarized model for UAV-correlated MIMO channels. By utilizing the geometrical theory of polarization, we describe the channel depolarization caused by the terrestrial scattering environment based on the multicylinder geometrical model and then acquire the channel polarization function and polarized channel impulse response (CIR). Furthermore, we investigate the impact of the key factors, such as the UAV tilt rotation, cross-polarization, and limited antenna spacing on the UAV MIMO channel capacity. To validate the proposed UAV channel model, we compare the spatial correlations of the numerical simulation and UAV field measurement results for the co- and cross-polarized channels, and the close agreements between them are observed. This work can provide useful guidance and support for the design and performance evaluation of UAV communication networks.

A simple analytical expression of quantum Fisher and Skew information and their dynamics under decoherence channels

In statistical estimation theory, it has been shown previously that the Wigner–Yanase skew information is bounded by the quantum Fisher information associated with the phase parameter. Besides, the quantum Cramér–Rao inequality is expressed in terms of skew information. Since these two fundamental quantities are based on the concept of quantum uncertainty, we derive here their analytical formulas for arbitrary two qubit X-states using the same analytical procedures. A comparison of these two informational quantifiers for two quasi-Werner states composed of two bipartite superposed coherent states is examined. Moreover, we investigated the decoherence effects on such quantities generated by the phase damping, depolarization and amplitude damping channels. We showed that decoherence strongly influences the quantum criteria during the evolution and these quantities exhibit similar dynamic behaviors. This current work is characterized by the fact that these two concepts play the same role and capture similar properties in quantum estimation protocols.

Muscarinic Acetylcholine Receptors Modulate HCN Channel Properties in Vestibular Ganglion Neurons.

Efferent modulation of vestibular afferent excitability is linked to muscarinic signaling cascades that close low-voltage-gated potassium channels (i.e., KCNQ). Here, we show that muscarinic signaling cascades also depolarize the activation range of hyperpolarization-activated cyclic-nucleotide gated (HCN) channels. We compared the voltage activation range and kinetics of HCN channels and induced firing patterns before and after administering the muscarinic acetylcholine receptor (mAChR) agonist oxotremorine-M (Oxo-M) in dissociated vestibular ganglion neurons (VGNs) from rats of either sex using perforated whole-cell patch-clamp methods. Oxo-M depolarized HCN channels' half-activation voltage (V 1/2) and sped up the rate of activation near resting potential twofold. HCN channels in large-diameter and/or transient firing VGN (putative cell bodies of irregular firing neuron from central epithelial zones) had relatively depolarized V 1/2 in control solution and were less sensitive to mAChR activation than those found in small-diameter VGN with sustained firing patterns (putatively belonging to regular firing afferents). The impact of mAChR on HCN channels is not a direct consequence of closing KCNQ channels since pretreating the cells with Linopirdine, a KCNQ channel blocker, did not prevent HCN channel depolarization by Oxo-M. Efferent signaling promoted ion channel configurations that were favorable to highly regular spiking in some VGN, but not others. This is consistent with previous observations that low-voltage gated potassium currents in VGN are conducted by mAChR agonist-sensitive and -insensitive channels. Connecting efferent signaling to HCN channels is significant because of the channel's impact on spike-timing regularity and nonchemical transmission between Type I hair cells and vestibular afferents.SIGNIFICANCE STATEMENT Vestibular afferents express a diverse complement of ion channels. In vitro studies identified low-voltage activated potassium channels and hyperpolarization-activated cyclic-nucleotide gated (HCN) channels as crucial for shaping the timing and sensitivity of afferent responses. Moreover, a network of acetylcholine-releasing efferent neurons controls afferent excitability by closing a subgroup of low-voltage activated potassium channels on the afferent neuron. This work shows that these efferent signaling cascades also enhance the activation of HCN channels by depolarizing their voltage activation range. The size of this effect varies depending on the endogenous properties of the HCN channel and on cell type (as determined by discharge patterns and cell size). Simultaneously controlling two ion-channel groups gives the vestibular efferent system exquisite control over afferent neuron activity.

Prolonging valley polarization lifetime through gate-controlled exciton-to-trion conversion in monolayer molybdenum ditelluride

Monolayer 2D semiconductors provide an attractive option for valleytronics due to valley-addressability. But the short valley-polarization lifetimes for excitons have hindered potential valleytronic applications. In this paper, we demonstrate a strategy for prolonging the valley-polarization lifetime by converting excitons to trions through efficient gate control and exploiting the much longer valley-polarization lifetimes for trions than for excitons. At charge neutrality, the valley lifetime of monolayer MoTe2 increases by a factor of 1000 to the order of nanoseconds from excitons to trions. The exciton-to-trion conversion changes the dominant depolarization mechanism from the fast electron-hole exchange for excitons to the slow spin-flip process for trions. Moreover, the degree of valley polarization increases to 38% for excitons and 33% for trions through electrical manipulation. Our results reveal the depolarization dynamics and the interplay of various depolarization channels for excitons and trions, providing an effective strategy for prolonging the valley polarization.

A Systematic Review and Meta-Analysis of the Effect of Intraoperative Bupivacaine in Gynaecologic Surgery After 24 Hours or 9 Half-Lives.

To review all high quality available evidence regarding the effect of intraoperative bupivacaine 24 hours (or 8.9 half-lives) after intraoperative administration at time of gynaecologic surgery and to ascertain whether a second mechanism of action, beyond the initial prevention of sodium channel depolarization and blockade of nerve impulses, may be occurring. We searched all major databases with an algorithm designed to include all randomized trials that used any form of local bupivacaine, regardless of dose or route of administration, at the time of any gynaecologic surgery and compared its use with saline placebo. As expected, we found that bupivacaine showed a significant improvement for all gynaecologic surgeries with respect to pain intensity at 6 hours after surgery when compared with a saline group (mean difference [MD] -1.28; 95% CI -1.96 to -0.61], P=0.07). We also found a significant difference at 24 hours after surgery, giving evidence to the possibility of a second mechanism of action (MD -0.57; 95% CI -1.10 to -0.05], P=0.01). Further subgroup analysis for pain levels at 24 hours showed significant decreases in pain for the laparoscopy (MD -0.74; 95% CI -0.93 to -0.54, P < 0.01) and laparotomy (MD -2.60; 95% CI -2.93 to -2.27, P < 0.01)) subgroups but not for the vaginal hysterectomy (MD 0.20; 95% CI -0.69 to 1.09, P=0.66) or prolapse surgery (MD -0.11; 95% CI -0.41 to 0.19, P=0.48) subgroups. There was no significant difference with respect to the length of hospital stay (MD -0.11; 95% CI -0.59 to 0.38, P=0.67). As expected, bupivacaine significantly reduced visual analog pain scores when compared with placebo at 6 hours after surgery, but also showed a significant difference at 24 hours after surgery, giving evidence of a second mechanism of action following the initial sodium channel blockade.

Analysis of a High-Dimensional Extended B92 Protocol

Quantum key distribution (QKD) allows two parties to establish a shared secret key that is secure against adversaries with unlimited computational power. One such protocol named B92 is quite appealing due to its simplicity but is highly sensitive to channel noise. In this work, we investigate a high-dimensional variant of an extended version of the B92 protocol and show that it can distill a key over high noise channels. The protocol we consider requires that Alice sends only three high-dimensional states and Bob only performs partial measurements. We perform an information-theoretic security analysis of our protocol and compare its key rate to that of a high-dimensional BB84 protocol over depolarization and amplitude damping channels.

Soft decoding of short/medium length codes using ordered statistics for quantum key distribution

Quantum key distribution (QKD) is a cryptographic communication protocol that utilizes quantum mechanical properties for provable absolute security against an eavesdropper. The communication is carried between two terminals using random photon polarization states represented through quantum states. Both these terminals are interconnected through disjoint quantum and classical channels. Information reconciliation using delay controlled joint decoding is performed at the receiving terminal. Its performance is characterized using data and error rates. Achieving low error rates is particularly challenging for schemes based on error correcting codes with short code lengths. This article addresses the decoding process using ordered statistics decoding for information reconciliation of both short and medium length Bose–Chaudhuri–Hocquenghem codes over a QKD link. The link’s quantum channel is modeled as a binary symmetric quantum depolarization channel, whereas the classical channel is configured with additive white Gaussian noise. Our results demonstrate the achievement of low bit error rates, and reduced decoding complexity when compared to other capacity achieving codes of similar length and configuration.

Low-loss belief propagation decoder with Tanner graph in quantum error-correction codes

Quantum error-correction codes are immeasurable resources for quantum computing and quantum communication. However, the existing decoders are generally incapable of checking node duplication of belief propagation (BP) on quantum low-density parity check (QLDPC) codes. Based on the probability theory in the machine learning, mathematical statistics and topological structure, a GF(4) (the Galois field is abbreviated as GF) augmented model BP decoder with Tanner graph is designed. The problem of repeated check nodes can be solved by this decoder. In simulation, when the random perturbation strength p=0.0115–0.0116 and number of attempts N = 60–70, the highest decoding efficiency of the augmented model BP decoder is obtained, and the low-loss frame error rate (FER) decreases to 7.1975 ×10−5. Hence, we design a novel augmented model decoder to compare the relationship between GF(2) and GF(4) for quantum code [[450,200]] on the depolarization channel. It can be verified that the proposed decoder provides the widely application range, and the decoding performance is better in QLDPC codes.

Ageing contributes to phenotype transition in a mouse model of periodic paralysis.

BackgroundPeriodic paralysis (PP) is a rare genetic disorder in which ion channel mutation causes episodic paralysis in association with hyper‐ or hypokalaemia. An unexplained but consistent feature of PP is that a phenotype transition occurs around the age of 40, in which the severity of potassium‐induced muscle weakness declines but onset of fixed, progressive weakness is reported. This phenotype transition coincides with the age at which muscle mass and optimal motor function start to decline in healthy individuals. We sought to determine if the phenotype transition in PP is linked to the normal ageing phenotype transition and to explore the mechanisms involved.MethodsA mouse model of hyperkalaemic PP was compared with wild‐type littermates across a range of ages (13–104 weeks). Only male mice were used as penetrance is incomplete in females. We adapted the muscle velocity recovery cycle technique from humans to examine murine muscle excitability in vivo. We then examined changes in potassium‐induced weakness or caffeine contracture force with age using ex vivo muscle tension testing. Muscles were further characterized by either Western blot, histology or energy charge measurement. For normally distributed data, a student's t‐test (± Welch correction) or one‐ or two‐way analysis of variance (ANOVA) was performed to determine significance. For data that were not normally distributed, Welch rank test, Mann Whitney U test or Kruskal–Wallis ANOVA was performed. When an ANOVA was significant (P < 0.05), post hoc Tukey testing was used.ResultsBoth WT (P = 0.009) and PP (P = 0.007) muscles exhibit increased resistance to potassium‐induced weakness with age. Our data suggest that healthy‐old muscle develops mechanisms to maintain force despite sarcolemmal depolarization and sodium channel inactivation. In contrast, reduced caffeine contracture force (P = 0.00005), skeletal muscle energy charge (P = 0.004) and structural core pathology (P = 0.005) were specific to Draggen muscle, indicating that they are caused, or at least accelerated by, chronic genetic ion channel dysfunction.ConclusionsThe phenotype transition with age is replicated in a mouse model of PP. Intrinsic muscle ageing protects against potassium‐induced weakness in HyperPP mice. However, it also appears to accelerate impairment of sarcoplasmic reticulum calcium release, mitochondrial impairment and the development of core‐like regions, suggesting acquired RyR1 dysfunction as the potential aetiology. This work provides a first description of mechanisms involved in phenotype transition with age in PP. It also demonstrates how studying phenotype transition with age in monogenic disease can yield novel insights into both disease physiology and the ageing process itself.

Optimal measurement preserving qubit channels

We consider the problem of discriminating qubit states that are sent over a quantum channel and derive a necessary and sufficient condition for an optimal measurement to be preserved by the channel. We apply the result to the characterization of optimal measurement preserving (OMP) channels for a given qubit ensemble, e.g., a set of two states or a set of multiple qubit states with equal a priori probabilities. Conversely, we also characterize qubit ensembles for which a given channel is OMP, such as unitary and depolarization channels. Finally, we show how the sets of OMP channels for a given ensemble can be constructed.

Monitoring Dust Events Using Doppler Lidar and Ceilometer in Iceland

Ground-based lidars and ceilometers are widely used for dust and volcanic ash observation around the world. This is particularly interesting in Iceland where high-altitude dust events occur frequently during strong wind conditions and volcanic eruptions. To explore the possible application of such technologies in Iceland for monitoring dust events, we used a combination of Doppler wind lidars with depolarization channels, ceilometers, and other instruments, to monitor two dust events that occurred in Iceland during summer 2019. We applied a verified ceilometer data processing procedure with customized local corrections and developed a new procedure to process Doppler lidar data for aerosols measurements. Both lidar and ceilometer observations can be used to detect the dust layer and reveal the temporal and vertical distribution of dust aerosols in Iceland. The depolarization ratio measurements indicate that the weather conditions, e.g., relative humidity, could have a significant impact on lidar measurements. We conclude that using Doppler wind lidar and ceilometer measurements to monitor volcanic and sedimentary aerosols is possible and may be used to provide important information to the scientific community.

4-Oxatricyclo[5.2.1.02,6]dec-8-ene-3,5-dione Derivatives as NMDA Receptor- and VGCC Blockers with Neuroprotective Potential.

The impact of excitotoxicity mediated by N-methyl-D-aspartate (NMDA) receptor overactivation and voltage gated calcium channel (VGCC) depolarization is prominent among the postulated processes involved in the development of neurodegenerative disorders. NGP1-01, a polycyclic amine, has been shown to be neuroprotective through modulation of the NMDA receptor and VGCC, and attenuation of MPP+-induced neurotoxicity. Recently, we reported on the calcium modulating effects of tricycloundecene derivatives, structurally similar to NGP1-01, on the NMDA receptor and VGCC of synaptoneurosomes. In the present study, we investigated novel 4-oxatricyclo[5.2.1.02,6]dec-8-ene-3,5-dione derivatives for their cytotoxicity, neuroprotective effects via attenuation of MPP+-induced neurotoxicity and calcium influx inhibition abilities through the NMDA receptor and VGCC using neuroblastoma SH-SY5Y cells. All compounds, in general, showed low or no toxicity against neuroblastoma cells at 10–50 µM concentrations. At 10 µM, all compounds significantly attenuated MPP+-induced neurotoxicity as evident by the enhancement in cell viability between 23.05 ± 3.45% to 53.56 ± 9.29%. In comparison to known active compounds, the derivatives demonstrated mono or dual calcium modulating effect on the NMDA receptor and/or VGCC. Molecular docking studies using the NMDA receptor protein structure indicated that the compounds are able to bind in a comparable manner to the crystallographic pose of MK-801 inside the NMDA ion channel. The biological characteristics, together with results from in silico studies, suggest that these compounds could act as neuroprotective agents for the purpose of halting or slowing down the degenerative processes in neuronal cells.