2,543 research outputs found

    Implications of sudden oak death for wildland fire management

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    Human activities and climate change have altered historical disturbance regimes, introduced disturbances, and encouraged novel interactions between multiple disturbances. Ecosystems and the species that comprise them may be poorly equipped to withstand or recover from these altered disturbance regimes. In the fire-prone coastal forests of California and Oregon, sudden oak death (SOD), caused by the pathogen Phytophthora ramorum, is an emerging, non-native plant disease that causes widespread tree mortality and associated implications for fire regimes. Disease-related tree mortality alters fuel loads, with patterns of fuel accumulation varying depending on stand composition, disease severity, and time since pathogen invasion. Simulations and observational studies suggest these altered fuel profiles can impact subsequent fire behavior, and the extent of this interaction may depend on the severity and timing of disease impacts. Initial tree death can elevate the risk of crown ignition, while latter stages can increase surface fuel loading and have been linked to increased fire severity in wildfires. Further, disease history can also influence fire severity with cascading effects leading to unexpected increases in mortality of non-susceptible tree species and changes in nutrient cycling. The longer-term impacts of SOD-fire interactions on system resilience and recovery remain to be seen, but increased fire severity, changed stand structure, and altered biogeochemical cycling may have important consequences for post-fire regeneration and future ecosystem function. Fuels management strategies that diminish crown fire hazards at early stages and mitigate surface fuel hazards at later stages offer some promise, but have yet to be tested in large landscapes. Given SOD-wildfire interactions, further integration of disease- and fire-related management plans will be essential to minimizing impacts of these compounded disturbances

    Altered Anesthetic Sensitivity of Mice Lacking Ndufs4, a Subunit of Mitochondrial Complex I

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    RDP and AQ were supported by the Howard Hughes Medical Institute (HHMI). AQ was a recipient of MICINN postdoctoral mobility program fellowship from the Spanish Ministerio de Ciencia e Innovación. PGM and MMS were supported by National Institutes of Health (NIH) grant GM58881. These studies were also supported in part by the Mitochondrial Research Guild. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Anesthetics are in routine use, yet the mechanisms underlying their function are incompletely understood. Studies in vitro demonstrate that both GABAA and NMDA receptors are modulated by anesthetics, but whole animal models have not supported the role of these receptors as sole effectors of general anesthesia. Findings in C. elegans and in children reveal that defects in mitochondrial complex I can cause hypersensitivity to volatile anesthetics. Here, we tested a knockout (KO) mouse with reduced complex I function due to inactivation of the Ndufs4 gene, which encodes one of the subunits of complex I. We tested these KO mice with two volatile and two non-volatile anesthetics. KO and wild-type (WT) mice were anesthetized with isoflurane, halothane, propofol or ketamine at post-natal (PN) days 23 to 27, and tested for loss of response to tail clamp (isoflurane and halothane) or loss of righting reflex (propofol and ketamine). KO mice were 2.5 - to 3- fold more sensitive to isoflurane and halothane than WT mice. KO mice were 2-fold more sensitive to propofol but resistant to ketamine. These changes in anesthetic sensitivity are the largest recorded in a mammal

    Brief of Scholars of the History and Original Meaning of the Fourth Amendment as Amici Curiae in Support of Petitioner, Carpenter v. United States, No. 16-402 (U.S. Aug. 14, 2017)

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    Obtaining and examining cell site location records to find a person is a “search” in any normal sense of the word — a search of documents and a search for a person and her personal effects. It is therefore a “search” within the meaning of the Fourth Amendment in that it constitutes “examining,” “exploring,” “looking through,” “inquiring,” “seeking,” or “trying to find.” Nothing about the text of the Fourth Amendment, or the historical backdrop against which it was adopted, suggests that “search” should be construed more narrowly as, for example, intrusions upon subjectively manifested expectations of privacy that society is prepared to recognize as reasonable.Entrusting government agents with unfettered discretion to conduct searches using cell site location information undermines Fourth Amendment rights. The Amendment guarantees “[t]he right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches.” The Framers chose that language deliberately. It reflected the insecurity they suffered at the hands of “writs of assistance,” a form of general warrant that granted state agents broad discretion to search wherever they pleased. Such arbitrary power was “unreasonable” to the Framers, being “against the reason of the common law,” and it was intolerable because of its oppressive impact on “the people” as a whole. As emphasized in one of the seminal English cases that inspired the Amendment, this kind of general power to search was “totally subversive of the liberty of the subject.” James Otis’s famous speech denouncing a colonial writ of assistance similarly condemned those writs as “the worst instrument of arbitrary power,” placing “the liberty of every man in the hands of every petty officer.” Thus, although those who drafted and ratified the Fourth Amendment could not have anticipated cellphone technology, they would have recognized the dangers inherent in any state claim of unlimited authority to conduct searches for evidence of criminal activity. Cell site location information provides insight into where we go and what we do. Because this information is constantly generated and can be retrieved by the government long after the activities it memorializes have taken place, unfettered government access to cell site location information raises the specter of general searches and undermines the security of “the people.

    Complement and humoral adaptive immunity in the human choroid plexus: roles for stromal concretions, basement membranes, and epithelium

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    The choroid plexus (CP) provides a barrier to entry of toxic molecules from the blood into the brain and transports vital molecules into the cerebrospinal fluid. While a great deal is known about CP physiology, relatively little is known about its immunology. Here, we show immunohistochemical data that help define the role of the CP in innate and adaptive humoral immunity. The results show that complement, in the form of C1q, C3d, C9, or C9neo, is preferentially deposited in stromal concretions. In contrast, immunoglobulin (Ig) G (IgG) and IgA are more often found in CP epithelial cells, and IgM is found in either locale. C4d, IgD, and IgE are rarely, if ever, seen in the CP. In multiple sclerosis CP, basement membrane C9 or stromal IgA patterns were common but were not specific for the disease. These findings indicate that the CP may orchestrate the clearance of complement, particularly by deposition in its concretions, IgA and IgG preferentially via its epithelium, and IgM by either mechanism

    Frontal and parietal theta burst TMS impairs working memory for visual-spatial conjunctions

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    Open Access funded by Wellcome Trust Under a Creative Commons license Acknowledgments This research was supported by the Wellcome Trust (grant number 077185/Z/05/Z) and the Welsh Assembly Government through the Wales Institute of Cognitive Neuroscience.Peer reviewedPublisher PD

    Glutamatergic neurotransmission links sensitivity to volatile anesthetics with mitochondrial function

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    Actualment, Albert Quintana Romero desenvolupa la seva recerca a l'Institut de Neurociències de la Universitat Autònoma de BarcelonaAn enigma of modern medicine has persisted for over 150 years. The mechanisms by which volatile anesthetics (VAs) produce their effects (loss of consciousness, analgesia, amnesia, and immobility) remain an unsolved mystery. Many attractive putative molecular targets have failed to produce a significant effect when genetically tested in whole-animal models [1-3]. However, mitochondrial defects increase VA sensitivity in diverse organisms from nematodes to humans [4-6]. Ndufs4 knockout (KO) mice lack a subunit of mitochondrial complex I and are strikingly hypersensitive to VAs yet resistant to the intravenous anesthetic ketamine [7]. The change in VA sensitivity is the largest reported for a mammal. Limiting NDUFS4 loss to a subset of glutamatergic neurons recapitulates the VA hypersensitivity of Ndufs4(KO) mice, while loss in GABAergic or cholinergic neurons does not. Baseline electrophysiologic function of CA1 pyramidal neurons does not differ between Ndufs4(KO) and control mice. Isoflurane concentrations that anesthetize only Ndufs4(KO) mice (0.6%) decreased the frequency of spontaneous excitatory postsynaptic currents (sEPSCs) only in Ndufs4(KO) CA1 neurons, while concentrations effective in control mice (1.2%) decreased sEPSC frequencies in both control and Ndufs4(KO) CA1 pyramidal cells. Spontaneous inhibitory postsynaptic currents (sIPSCs) were not differentially affected between genotypes. The effects of isoflurane were similar on evoked field excitatory postsynaptic potentials (fEPSPs) and paired pulse facilitation (PPF) in KO and control hippocampal slices. We propose that CA1 presynaptic excitatory neurotransmission is hypersensitive to isoflurane in Ndufs4(KO) mice due to the inhibition of pre-existing reduced complex I function, reaching a critical reduction that can no longer meet metabolic demands
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