Добірка наукової літератури з теми "Cadiac rhythm"

Clients report more pain at some times of day than at others due, in part, to the temporal variation of the body's inhibitory pain response. The analgesic effectiveness of morphine varies with the time of day, perhaps due to the inhibiting or enhancing effects of the drug on plasma beta-endorphin (BE). This experiment was designed to examine the timed effects of morphine on the pain-induced BE response. Six groups of treatment mice (injected with morphine sulfate) and 6 groups of control mice (injected with saline) were exposed to an acute pain stimulus at 4-h intervals, and blood was collected. Plasma BE was analyzed using radioimmunoassay. Control mice showed a robust cir-cadian BE-response rhythm with a peak at 0000 and a nadir at 1200, whereas the BE response of mice that received morphine was arrhythmic. Animals that received morphine tolerated the noxious stimulus longer, but the analgesia varied with time of day. These results indicate that morphine abolishes the rhythmic BE response to pain and does not inhibit pain equally at all times of day. Morphine doses should be titrated to maximize the endogenous pain control system while achieving analgesia with decreased dosages.

Purpose. Purpose: In addition to the static observation of intraocular pressure at an arbitrary time point, the dynamic observation of intraocular pressure in the 24-hour rhythm is considered to be clinically useful in order to better assess the extent of day-night fluctuations. Material and Methods. The literature review includes the current state of knowledge regarding the 24-hour fluctua- tions in intraocular pressure as an independent risk factor for primary open-angle glaucoma. The literature search was performed with PubMed. Results. The intraocular pressure is neuronally regulated and is involved in the circadian regulation via the nucleus supra- chiasmaticus; the normal fluctuation in intraocular pressure is 5 mmHg. In the context of systemic neurodegeneration in primary open-angle glaucoma, there is also a disturbance of the cir- cadian rhythm. The fluctuations in intraocular pressure can be 10 mmHg or more and are an independent risk factor for glaucoma progression. Conclusion. Thus, the goal of successful glaucoma therapy is not only to achieve an individual target pressure range, but also to normalise abnormal circadian intraocular pressure fluctuations. Keywords glaucoma, circadian rhythm, neurodegeneration, oxidative stress

Oscillatory phase coupling within large-scale brain networks is a topic of increasing interest within systems, cognitive, and theoretical neuroscience. Evidence shows that brain rhythms play a role in controlling neuronal excitability and response modulation (Haider B, McCormick D. Neuron 62: 171–189, 2009) and regulate the efficacy of communication between cortical regions (Fries P. Trends Cogn Sci 9: 474–480, 2005) and distinct spatiotemporal scales (Canolty RT, Knight RT. Trends Cogn Sci 14: 506–515, 2010). In this view, anatomically connected brain areas form the scaffolding upon which neuronal oscillations rapidly create and dissolve transient functional networks (Lakatos P, Karmos G, Mehta A, Ulbert I, Schroeder C. Science 320: 110–113, 2008). Importantly, testing these hypotheses requires methods designed to accurately reflect dynamic changes in multivariate phase coupling within brain networks. Unfortunately, phase coupling between neurophysiological signals is commonly investigated using suboptimal techniques. Here we describe how a recently developed probabilistic model, phase coupling estimation (PCE; Cadieu C, Koepsell K Neural Comput 44: 3107–3126, 2010), can be used to investigate changes in multivariate phase coupling, and we detail the advantages of this model over the commonly employed phase-locking value (PLV; Lachaux JP, Rodriguez E, Martinerie J, Varela F. Human Brain Map 8: 194–208, 1999). We show that the N-dimensional PCE is a natural generalization of the inherently bivariate PLV. Using simulations, we show that PCE accurately captures both direct and indirect (network mediated) coupling between network elements in situations where PLV produces erroneous results. We present empirical results on recordings from humans and nonhuman primates and show that the PCE-estimated coupling values are different from those using the bivariate PLV. Critically on these empirical recordings, PCE output tends to be sparser than the PLVs, indicating fewer significant interactions and perhaps a more parsimonious description of the data. Finally, the physical interpretation of PCE parameters is straightforward: the PCE parameters correspond to interaction terms in a network of coupled oscillators. Forward modeling of a network of coupled oscillators with parameters estimated by PCE generates synthetic data with statistical characteristics identical to empirical signals. Given these advantages over the PLV, PCE is a useful tool for investigating multivariate phase coupling in distributed brain networks.

Let me walk. Let me go at my own pace. Let me feel life as it moves through me and around me. Give me drama. Give me unexpected curvilinear corners. Give me unsettling churches and beautiful storefronts and parks I can lie down in. The city turns you on, gets you going, moving, thinking, wanting, engaging (Elkin 37, emphasis our own). Walking Is ThinkingAs feet pound the pavement, synaptic movement follows. To clear the head, one must get up and walk.In her 2016 book Flaneuse: Women Walk the City in Paris, New York, Tokyo, Venice and London, Lauren Elkin traces the figure of the walking woman— often herself—through literary and artistic movements and the metropolis. She explores the act of flânerie, of wandering the city, as performed by George Sand, Virginia Woolf and Martha Gellhorn, amongst other peripatetic female thinkers. For Elkin, walking is at once an act of protest, of pleasure, a way to navigate personal pain, but also a way of thinking. She writes, “sometimes I walk because I have things on my mind, and walking helps me sort them out” (21).In “On the Rhythms of Walking and Seeing: Two Walks across the Page”, Evija Trofimova and Sophie Nicholls take this further, and amble towards one another thoughtfully, but from other sides of the globe. They address Elkins’s “sorting out” by coming together, not in the physical, but on the page. They address the frustration that can occur before the words appear on the page, when we as writers are “stuck”—and how moving away from the static confines of the office, away from the desk, and going for a walk, makes the work much richer when we return. Yet walking is more than that again: Trofimova and Nicholls also demonstrate how companionable the act of walking is, and how co-writing can achieve this simpatico too. Their essay is a conversation, a walk together, a work together. It is rhythmic and roaming, and like Elkin, references thinkers who have relied on the ramble to relieve the block.Walking Is WritingWhile we were editing this issue, Rebecca Solnit’s book Wanderlust: A History of Walking appeared on the reference list of many articles we received. Wanderlust, first published in 2001, has become a contemporary classic—part of a “Walking Canon”, if you will—for its exhaustive study of walking and its artistic, philosophical, and political histories. Like Trofimova and Nicholls, Daniel Juckes also engages with Solnit’s work in his article “Walking as Practice and Prose as Path Making: How Life Writing and Journey can Intersect.” Reflecting on W. G. Sebald, Marcel Proust, and the family memoir he was writing, Juckes refers to Solnit’s discussion of the connection between place, path, and memory. He writes that “if a person is searching for some kind of possible-impossible grounding in the past, then walking pace is the pace at which to achieve that sensation (both in the world and on the page).” Like in dreams, this realm of im/possibility can occur through writing, but is also fostered through walking. As Solnit reminds us, “exploring the world is one of the best ways of exploring the mind, and walking travels both terrains” (13). In Juckes’s work we see how walking and memory can be intimately connected; how both, as Juckes puts it, are bound up in “the making of connections between present and past,” as we tread across old associations and they are made anew.Walking Is PrivilegeAs we discuss the pedestrian benefits of walking, it would be remiss to fail to acknowledge those with restricted mobility due to a disability or illness. Ableism permeates the world we live in. As such, an important aspect of this issue is examining how issues relating to dis/ability are a critical part of discourses around walking, and highlight inequities in access and the language we use to discuss it.We are particularly proud of Chingshun Sheu’s article, “Forced Excursion: Walking as Disability in Joshua Ferris’s The Unnamed”, which engages with disability theory in its discussion of Ferris’s 2010 novel. In Ferris’s text, the protagonist’s involuntary stints of walking to exhaustion appear as disability, affecting his work, relationships and ultimately, his mortality. Sheu uses the text to explore the complexity and limitations of disability models, noting that “disability exists only at the confluence of differently abled minds and bodies and unaccommodating social and physical environs.”Walking Is PosthumanChantelle Bayes approaches these unaccommodating environs from a different angle, discussing how “marginalised groups are usually the most impacted by the strict control and ordering of contemporary urban spaces in response to utopian imaginaries of who and what belong.” Bayes’s article, “The Cyborg Flâneur: Reimagining Urban Nature through the Act of Walking”, recasts Benjamin’s flâneur as cyborg, drawing on feminist writings from Debra Benita Shaw, Rob Shields, and Donna Haraway—the latter of whom is particularly influential for her recent contributions to eco-feminist thought. Bayes takes us into virtual urban spaces, by examining how a revisionist concept of flânerie can be reconfigured online, allowing “for new environmental imaginaries to be created.” Bayes’s concept is at once exciting and daunting: is walking through an app what we have to look forward to in the age of the Anthropocene? Will our cities continue to be more accommodating to the lucky few? Walking as a non-corporeal action is an unsettling thought, and intriguing for this discomfort. Walking Is GentrificationLet us guide you through these city streets to our next article, as Craig Lyons, Alexandra Crosby and H. Morgan Harris take us to Sydney’s inner West, an area becoming increasingly unaccommodating for many thanks to rising living costs. Their article, “Going on a Field Trip: Critical Geographical Walking Tours and Tactical Media as Urban Praxis in Sydney, Australia”, situates us in Marrickville, which they remind us is “unceded land of the Cadigal and Wangal people of the Eora nation who call the area Bulanaming.” Already this space is contested, as all Australian urban spaces all, palimpsests of Indigeneity, colonisation, and capital. Field Trip recognises this layering, operating as “a critical geographical walking tour through an industrial precinct,” prompting participants to take part in an act of resistance merely by walking the space.It recalls Mirror Sydney, writer Vanessa Berry’s blog (a book of the same name was published this year) that maps Sydney’s disappearing quirks. In a June entry, she notes after a walk that “in the last week new signs have gone up, signs for the impending auction of the two warehouses that make up the green building: ‘Invest, Occupy or Redevelop.’ It’s the last option that has Marrickvillians nervous” (Berry). These redevelopment nerves are confronted by Lyons, Crosby, and Harris as they examine gentrification in the area, as developers seek to exploit the area’s diverse population to attract wealth. They see their walking tour as a work of activism, a way of confronting the rapid gentrification of their city, stating that “via a community-led, participatory walking tour like Field Trip, threads of knowledge and new information are uncovered. These help create new spatial stories and readings of the landscape, broadening the scope of possibility for democratic participation in cities.”Walking Is PoliticalBeing able to walk is to exercise democracy. Last year in Australia, Clinton Pryor, a Wajuk, Balardung, Kija and a Yulparitja man, walked from Perth, near his home in Western Australia, to Canberra, to protest the treatment of First Nations peoples in Australia (Morelli). Indeed, one of the places where Pryor, dubbed “the Spirit Walker”, met his most rapturous welcome was in Sydney’s Redfern, not far from Marrickville. When Pryor reached Redfern, and the crowd that awaited him, he said, “I just walked in here and can’t tell you what Redfern has meant to us all over the years. Everyone knows Redfern is where we made our stand,” referring to the place’s reputation as the heartland of Australia’s Black Power movement (Murphy).Pryor’s walk demonstrates ambulatory political power—it became a march. Alina Haliliuc transports us to Bucharest, far from Australia’s dusty roads, in her article “Walking into Democratic Citizenship: Anti-Corruption Protests in Romania’s Capital”. Like Pryor, the subjects of her article “have been using their bodies in public spaces to challenge politicians’ disregard for the average citizen.” Haliliuc draws attention to the how the Romanian public have mobilised, marching the streets and affecting real change, striving—or striding—for democracy in a region plagued by increasing political instability. Walking Is ArtFor about three years, from 1972, American artist Adrian Piper would dress up as a man she dubbed the “Mythic Being”, donning an afro wig, a moustache and sunglasses, walking the streets of New York City presenting as a man. She documented some of these public appearances in works that appeared in her 2018 retrospective at New York’s Museum of Modern Art (MoMA) titled “Adrian Piper: A Synthesis of Intuitions 1965-2016”. John Bowles writes that Piper, who is mixed race, uses the Mythic Being figure to “engage critically with popular representations of race, gender, sexuality, and class, challenging viewers to accept personal responsibility for xenophobia, discrimination, and the conditions that allow them to persist” (257). After being lucky enough to view the MoMA exhibition earlier this year, I was reminded of the Mythic Being when reading Derrais Carter’s article, “Black Wax(ing): On Gil Scott-Heron and the Walking Interlude”. Carter examines Scott-Heron’s walks through Washington, DC as shown in the 1982 film about the musician, Black Wax. Like much of Piper’s oeuvre, the film is a meditation on race and power in the United States, splicing footage of live performances with “walking interludes” such as Scott-Heron strolling past the White House with his toddler daughter. Carter remarks that he is “interested in the film as a wandering text, one that pushes at tensions in order to untether the viewer from a constricting narrative about who they might be”. Walking can perform this untethering, at once generating and diffusing tension about identity and space. Scott-Heron’s cinematic strolls through DC, filmed when conservative President Ronald Reagan was at the height of his power, demonstrate how walking can be a subversive, revolutionary form of artistic expression. Walking Is WayfindingIn the feature article of this special issue, “Walking as Memorial Ritual: Pilgrimage to the Past”, Susan Sigre Morrison explores the complex relationship between the human and the nonhuman and centres on pilgrimage to shape this discussion. Morrison traces four pilgrimages she has taken as a young child through to her adulthood, reflecting on memory, ecocriticism, the sacred, and the Anthropocene along the way. Thickly woven, Morrison’s writing ranges between her own memories, the limestone of the Jurassic, the life of a small insect she encounters in a meal, and extracts from her mother’s diary entries telling of hikes she undertook with the child Morrison. Throughout, Morrison dwells on Donna Haraway’s concept of “making kin”, and asks, “How can narrative avoid the anthropocentric centre of writing, which is inevitable given the human generator of such a piece?”In thinking about walking and her body, walking and memory, walking and the nonhuman world, walking in the city and the country, Morrison lays down the suggestions of paths that many of the articles in this special issue then follow. “Landscape not only changes the writer, but writing transforms the landscape and our interaction with it”, Morrison writes, voicing a sentiment that, in various ways, many of the authors in this issue, and the scholars and writers they discuss, hold to be true, and fascinating, and from which so much work and thought around walking springs.Why do we walk? This is the question that we as editors kept returning to, when first we had the idea to collate a special issue on walking. While the history of walking is a well-trodden path, reaching back to the Romantics in England, the flâneurs in Paris, and the psychogeographers in cities everywhere, we resolved to look to the walkers of the contemporary world for this issue. In an age of increasingly sophisticated and prevalent technology, what is the role of the embodied act, the lived experience, of walking? With this special issue, it is our pleasure to offer a selection of work that speaks to why we walk, how we walk, and what walking means in contemporaneity. We thank the contributors, and those who expressed their interest in contributing, as well as the anonymous peer reviewers, for their work—and we hope that this issue might inspire, or prompt, or remind you, the reader, to search out your own walks.ReferencesBerry, Vanessa. “The Ming On Building”. Mirror Sydney, 15 June 2018. 4 Oct. 2018 <https://mirrorsydney.wordpress.com/2018/06/15/the-ming-on-building/>.Bowles, John Parish. Adrian Piper: Race, Gender, and Embodiment. Durham: Duke University Press, 2011.Elkin, Lauren. Flâneuse: Women Walk the City in Paris, New York, Tokyo, Venice and London. London: Vintage, 2016.Morelli, Laura. “Spirit Walker, Clinton Pryor Reaches Redfern on His Walk for Justice.” NITV, 11 Aug. 2017. 4 Oct. 2018 <https://www.sbs.com.au/nitv/nitv-news/article/2017/08/11/spirit-walker-clinton-pryor-reaches-redfern-his-walk-justice>.Murphy, Damien. “Long Walk for Justice: ‘Spiritual Walker’ Clinton Pryor Crosses the Country for His People.” Sydney Morning Herald, 10 Aug. 2017. 4 Oct. 2018 <https://www.smh.com.au/national/nsw/long-walk-for-justice-spiritual-walker-clinton-pryor-crosses-the-country-for-his-people-20170810-gxtsnt.html>.Solnit, Rebecca. Wanderlust: A History of Walking. London: Granta, 2014.

Il recettore N-Metil-D-Aspartato è un recettore dell'acido glutammico ampiamente studiato nel sistema nervoso centrale. È costituito da 4 subunità, le quali unite costituiscono il canale ionotropico che permette il flusso di vari ioni attraverso la membrana plasmatica. Parecchi studi hanno evidenziato l’importanza dei recettori NMDA nel processo di neurotrasmissione, mentre pochi studi sono stati eseguiti per valutare l’impatto della funzione del recettore nel sistema cardiovascolare. Il lavoro presentato in questa tesi è stato sviluppato come progetto di ricerca internazionale congiunto iniziato nell’anno 2012, con la collaborazione tra due gruppi di ricerca, quello della Sezione di Cardiochirurgia del Dipartimento di Chirurgia - Università di Verona (I) e dell'Istituto di Fisiologia Veterinaria - Università di Zurigo (CH). Il progetto di ricerca vuole indagare il ruolo dei recettori NMDA nel cuore del mammifero sano e nel cuore del mammifero malato. Gli obiettivi di questo lavoro sono stati: • caratterizzare la composizione del recettore NMDA nelle sue subunità; • descrivere la distribuzione dei recettori attivi nelle cavità del cuore sia umano che animale (ratto); • valutare il compito di questi recettori nel ratto giovanile e invecchiato; • definire se il rimodellamento miocardico post-patologico nell’uomo può essere collegato alla funzione dei recettori NMDA cardiaci. Nello studio del cuore isolato del ratto mediante la perfusione con il sangue dell’animale stesso è risultato evidente l’effetto della somministrazione dei farmaci agonisti/antagonisti dei recettori NMDA sull’attività elettrica miocardica. Si è notato come i farmaci agonisti provocano sul miocardio reazioni tipo tachiaritmiche mentre i farmaci antagonisti producono una lieve bradicardia e stabilizzano il ritmo cardiaco. Nello studio sul cuore umano si è osservato che l’espessione di subunità GluN2A e GluN2C risultava significativamente inferiore nei pazienti con fibrillazione atriale cronica che nei pazienti con ritmo sinusale.
The N-methyl-D-aspartate (NMDA) receptor is glutamate receptor that has been widely studied in central nervous system. It consists of 4 subunits that build ionotropic channel allowing ion flow through the cell membrane. Many studies showed the importance of NMDA receptors in the process of neurotransmission but few studies has been performed to evaluate the impact of receptors' function to cardiovascular system. The work presented in this doctoral thesis has been within the international joint research project established in 2012 between two scientific groups of Division of Cardiac Surgery, Department of Surgery at the University of Verona (Italy) and the Institute of Veterinary Physiology at the University of Zurich (Switzerland). The project focused on the role of receptors in healthy and diseased mammalian heart. The aims of current work were: • to perform a basic characterisation of the subunit composition of NMDA receptor; • to describe the distribution of the active receptors within the heart chambers of human and animal (rat); • to evaluate the role of these receptors in young and old rats; • to define if pathological remodelling of myocardium in human may be connected with cardiac receptors' properties. In the isolated blood perfused rat heart study evidenced the effect of intracoronary administration of agonists and antagonists of the NMDA receptors on electrical activity of myocardium. It has been shown that exposure to agonists provoke tachyarrhythmic reactions while antagonists produce mild bradycardia and stabilise the heart rhythm. In the study on the human heart it was observed that the expression of GluN2A and GluN2C subunits was significantly lower in patients with chronic atrial fibrillation rather than in patients with sinus rhythm.

This thesis is a French-Czech contrastive study which deals with schwa (mute E) in the two languages. It is conducted in a pedagogical perspective. After comparing the principal phonetic/phonological characteristics of the two languages, the topic of the theoretical part is schwa in spoken French. One of the chapters concerns the treatment of mute E in French songs and its treatment in poetry. The second part consists in an experimental study ; it contains the description and the results of three experiments concerning the two languages. The acoustic realization of schwa (or a "schwa-like" vocalic segment) is observed through production tasks and perception tests of syllabicity in French and Czech words. The acoustic analyses seem to support the well-known hypotheses that it is not just the effect of the phonological cribble, but also a mental representation of the graphical form that is operating in the process of the perception of a foreign language. Furthermore, the representation of the graphical form seems to play a role for French listeners when hearing their own language. The articulatory habits of native speakers can considerably influence not only the production of a foreign language being studied, but also its perception. In the case of our first two perception tests the French listeners were...