227 research outputs found

    Turbulence properties and kinetic signatures of electron in Kelvin-Helmholtz waves during a geomagnetic storm

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    We present a comprehensive study of Magnetospheric Multiscale (MMS) spacecraft encounter with KHI during a geomagnetic storm, focusing on elucidating key turbulence properties and reconnection signatures observed at the edges of KH vortices. The spectral slope for electric field stays approximately constant for frequencies below the ion cyclotron frequency and exhibits a break around the lower hybrid frequency, indicating wave activity. Furthermore, MMS observes a current sheet accompanied by intense electron jets and features consistent with strong guide-field asymmetric reconnection across the magnetopause. Substantial agyrotropy (by a factor of 10) in electron distribution functions is observed in the reconnecting current sheet and at the edges of KH. Our observation presents a multi-scale view into KH turbulence under strongly driven conditions and into the dynamics occurring at electron dissipation scales.Comment: 10 pages, including 4 figure

    Real-world word learning: exploring children's developing semantic representations of a science term

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    Assessments of lexical acquisition are often limited to pre-school children on forced choice comprehension measures. This study assessed the understandings 30 school-age children (mean age = 6;7) acquired about the science term, eclipse following a naturalistic exposure to a solar eclipse. The knowledge children acquired about eclipses and a control term, comet was assessed at three points in time (baseline-test, two-week post-test and five-month post-test) using a range of assessment tasks (multiple-choice comprehension, picture-naming, drawing and a model of a solar system task). Children's knowledge was compared to 15 adult controls during the baseline-test and two-week post-test. Children acquired extensive knowledge about eclipses, but not comets; at the two-week post-test and five-month post-test, the majority of children named and drew eclipses and „made? an eclipse using models of the sun, moon and earth. Also, children's eclipse knowledge more closely approximated adult-level understandings at the two-week post-test than at the baseline-test. Implications for the study of lexical acquisition in later development are discussed

    Cyclotron resonance in the layered perovskite superconductor Sr2RuO4

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    We report a detailed study of the magnetic-field-orientation dependence of the millimetre-wave magnetoconductivity of the superconductor Sr2RuO4 We find two harmonic series of cyclotron resonances. We assign the first, corresponding to a quasiparticle mass of 4.29±0.05me4.29 \pm 0.05 m_{\rm e}, where mem_{\rm e} is the free-electron mass, to the β\beta Fermi-surface section. We assign the second series, which contains only odd harmonics, to cyclotron resonance of the γ\gamma Fermi-surface section, yielding a quasiparticle mass of 12.35±0.20me12.35 \pm 0.20 m_{\rm e}. A third, single cyclotron resonance, corresponding to a quasiparticle mass of 5.60±0.03me5.60 \pm 0.03 m_{\rm e}, is attributed to the α\alpha Fermi-surface section. In addition, we find a very strong absorption mode in the presence of a magnetic field component parallel to the quasi-two-dimensional planes of the sample. Its dependence on the orientation of the magnetic field cannot be described in the context of conventional cyclotron resonance, and the origin of this mode is not yet clear.Comment: Submitted to J. Phys. Cond. Ma

    Psilocybin prevents symptoms of hyperarousal and enhances novel object recognition in rats exposed to the single prolonged stress paradigm

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    Pharmacotherapy for stress-related psychological disorders remains inadequate. Patients who are treated with conventional pharmacological agents frequently report negligeable symptom reduction, and, in most cases, less than 50% experience full remission. Clearly, there is a need for additional pharmaceutical research into both established and novel approaches to alleviate these conditions. Over the past several years, there has been a renewed interest in the use of psychedelics to aid in the treatment of psychological disorders. Several studies have reported promising results in patients with major depression, anxiety disorders, and post-traumatic stress disorder (PTSD) following treatment with psychedelic agents such as lysergic acid diethylamide (LSD), 3,4-methylenedioxymethamphetamine (MDMA), ayahuasca, ketamine, and psilocybin. However, the precise behavioral and neurobiological mechanisms for these effects remain unclear. Thus, we aimed to develop an animal model of PTSD that involved prophylactic treatment with psilocybin, a 5-HT2A agonist, that could be used to further understand the mechanisms underlying the benefit of psychedelic substances in treating these disorders. Adult male and female Sprague-Dawley rats were subjected to the single prolonged stress (SPS) paradigm, including 2 hours of physical restraint, 15 minutes of forced swim, and ether vapor exposure until loss of consciousness. Five minutes following ether-induced loss of consciousness, the rats were intraperitoneally injected with vehicle (0.9% saline) or psilocybin (1 mg/kg). One week later, the rats underwent a battery of behavioral tests, including the elevated plus maze (EPM), startle response assessment, open field testing, and novel object recognition (NOR) testing. No effects of SPS or psilocybin were observed for EPM behavior. SPS led to enhanced startle responses in males, but not females, which was prevented by psilocybin. SPS also increased locomotor activity in the open field in males, but not females, and this effect was not prevented by psilocybin. SPS had no impact on NOR memory in males, but enhanced memory in females. Interestingly, psilocybin administration, alone or in combination with SPS, enhanced NOR memory in males only. These findings support a complex interaction between the administration of psilocybin and the prevention of stress-induced behavioral sequelae that depends on both sex and the type of behavioral task

    Low-dose psilocybin enhances novel object recognition but not inhibitory avoidance in adult rats

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    Given the recently renewed interest in using psychedelics to aid in the treatment of psychological disorders, we aimed to examine the impact of psilocybin, a 5-HT2A agonist, on learning and memory in rodents. Previous work has demonstrated that psilocybin and other 5-HT2A agonists can enhance fear conditioning, fear extinction, and novel object recognition (NOR). Thus, we predicted that low doses of psilocybin would enhance inhibitory avoidance (IA) and NOR memory. In the first experiment, adult male and female Sprague-Dawley rats underwent step-through IA training (involving 0.45, 0.65, or 1 mA scrambled footshock) and were injected intraperitoneally (i.p.) with vehicle (0.9% saline) or psilocybin (1 mg/kg) immediately afterward. Rats were tested for their IA memory two days later. In the second experiment, adult male and female Sprague-Dawley rats were acclimated to an open field apparatus for 5 minutes on Day 1. The next day, the rats were given i.p. injections of vehicle or psilocybin (0.1 mg/kg) 10 minutes before undergoing NOR training, during which they were exposed to two replicas of an identical object for 3 minutes. On Day 3, one of the objects from NOR training was exchanged for a novel object; rats were exposed to this novel object and a new replica of the object from Day 2 (i.e., familiar object) for 5 minutes. The results showed that psilocybin had no significant impact on IA memory but enhanced novel object recognition memory in both males and females. The differential impact of psilocybin on IA memory and novel object recognition could be explained by the different doses of psilocybin or the different times of drug administration used for each task. Alternatively, they may suggest that psilocybin exerts distinct effects on different types of learning

    Whale Baleen To Monitor Per- and Polyfluoroalkyl Substances (PFAS) in Marine Environments

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    Per- and polyfluoroalkyl substances (PFAS) comprise \u3e10 000 synthetic compounds that are globally distributed and highly persistent but remain challenging to monitor. Here we assess the utility of baleen─an accreting, keratinaceous tissue that baleen whales use for filter-feeding─to track PFAS dynamics in marine food webs. In six species investigated, PFAS were detected in all baleen tested (n = 18 plates, 220 samples, ∑10PFAS range of 0.02–60.5 ng/g of dry weight), at levels higher than those of other tissue types besides liver. Three of the species in our data set had not been tested for PFAS contamination previously, and two of those species (blue whale and North Atlantic right whale) are internationally endangered species. Apparent links were observed between PFAS and life-history events by testing successive subsamples along the growth axis of the baleen plates. These results establish baleen as a viable sample matrix for assessing PFAS contamination in marine ecosystems by enabling multiyear time-series analyses through single-tissue sampling with seasonal resolution

    Differential Regulation of Lipoprotein and Hepatitis C Virus Secretion by Rab1b

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    Secretory cells produce diverse cargoes, yet how they regulate concomitant secretory traffic remains insufficiently explored. Rab GTPases control intracellular vesicular transport. To map secretion pathways, we generated a library of lentivirus-expressed dominant-negative Rab mutants and used it in a large-scale screen to identify regulators of hepatic lipoprotein secretion. We identified several candidate pathways, including those mediated by Rab11 and Rab8. Surprisingly, inhibition of Rab1b, the major regulator of transport from the endoplasmic reticulum to the Golgi, differently affected the secretion of the very-low-density lipoprotein components ApoE and ApoB100, despite their final association on mature secreted lipoprotein particles. Since hepatitis C virus (HCV) incorporates ApoE and ApoB100 into its virus particle, we also investigated infectious HCV secretion and show that its regulation by Rab1b mirrors that of ApoB100. These observations reveal differential regulation of hepatocyte secretion by Rab1b and advance our understanding of lipoprotein assembly and lipoprotein and HCV secretion

    ABA Criminal Justice Section Task Force on College Due Process Rights and Victim Protections: Recommendations for Colleges and Universities in Resolving Allegations of Campus Sexual Misconduct

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    The Executive Committee of the ABA Criminal Justice Section commissioned the Task Force on College Due Process Rights and Victim Protections in November 2016. Immediately after, extensive efforts were made to find members that represented all interested parties: victims, the accused, universities, other stakeholders, and national experts. The Task Force was fully constituted in the winter of 2017, and it ended up including two voting members who were originally liaisons from the ABA Commission on Domestic and Sexual Violence and the ABA Section of Civil Rights and Social Justice. This elevation was made in recognition of their significant contributions

    The Intriguing Effects of Substituents in the N-Phenethyl Moiety of Norhydromorphone: A Bifunctional Opioid from a Set of “Tail Wags Dog” Experiments

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    This work is licensed under a Creative Commons Attribution 4.0 International License.(−)-N-Phenethyl analogs of optically pure N-norhydromorphone were synthesized and pharmacologically evaluated in several in vitro assays (opioid receptor binding, stimulation of [35S]GTPγS binding, forskolin-induced cAMP accumulation assay, and MOR-mediated β-arrestin recruitment assays). “Body” and “tail” interactions with opioid receptors (a subset of Portoghese’s message-address theory) were used for molecular modeling and simulations, where the “address” can be considered the “body” of the hydromorphone molecule and the “message” delivered by the substituent (tail) on the aromatic ring of the N-phenethyl moiety. One compound, N-p-chloro-phenethynorhydromorphone ((7aR,12bS)-3-(4-chlorophenethyl)-9-hydroxy-2,3,4,4a,5,6-hexahydro-1H-4,12-methanobenzofuro[3,2-e]isoquinolin-7(7aH)-one, 2i), was found to have nanomolar binding affinity at MOR and DOR. It was a potent partial agonist at MOR and a full potent agonist at DOR with a δ/μ potency ratio of 1.2 in the ([35S]GTPγS) assay. Bifunctional opioids that interact with MOR and DOR, the latter as agonists or antagonists, have been reported to have fewer side-effects than MOR agonists. The p-chlorophenethyl compound 2i was evaluated for its effect on respiration in both mice and squirrel monkeys. Compound 2i did not depress respiration (using normal air) in mice or squirrel monkeys. However, under conditions of hypercapnia (using air mixed with 5% CO2), respiration was depressed in squirrel monkeys.NIDA grant P30 DA13429NIDA grant DA039997NIDA grant DA018151NIDA grant DA035857NIDA grant DA047574NIH Intramural Research Programs of the National Institute on Drug AbuseNational Institute of Alcohol Abuse and AlcoholismNIH Intramural Research Programs of the National Institute on Drug AbuseNIH Intramural Research Program through the Center for Information TechnologyNIH Intramural Research Programs of the National Institute on Drug Abus

    Nantenine: an antagonist of the behavioral and physiological effects of MDMA in mice

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    No selective antagonists for the effects of MDMA have yet been identified. The structurally-similar, naturally-occurring plant alkaloid nantenine (9,10-methylenedioxy-1,2 dimethoxyaporphine) may represent such a compound.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/46360/1/213_2003_Article_1741.pd
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