944 resultados para Ultradian rhythm


Relevância:

10.00% 10.00%

Publicador:

Resumo:

Background: The biorhythm of serum uric acid was evaluated in a large sample of a clinical laboratory database by spectral analysis and the influence of the gender and age on uric acid variability. Methods: Serum uric acid values were extracted from a large database of a clinical laboratory from May 2000 to August 2006. Outlier values were excluded from the analysis and the remaining data (n = 73,925) were grouped by gender and age ranges. Rhythm components were obtained by the Lomb Scargle method and Cosinor analysis. Results: Serum uric acid was higher in men than in women older than 13 years (p<0.05). Compared with 0-12 year group, uric acid increased in men but not in women older than 13 years (p<0.05). Circannual (12 months) and transyear (17 months) rhythm components were detected, but they were significant only in adult individuals (>26 years, p<0.05). Cosinor analysis showed that midline estimating statistic of rhythm (MESOR) values were higher in men (range: 353-368 mu mol/L) than in women (range: 240-278 mu mol/L; p<0.05), independent of the age and rhythm component. The extent of predictable change within a cycle, approximated by the double amplitude, represented up to 20% of the corresponding MESOR. Conclusions: Serum uric acid biorhythm is dependent on gender and age and it may have relevant influence on preanalytical variability of clinical laboratory results.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The striatum, the largest component of the basal ganglia, is usually subdivided into associative, motor and limbic components. However, the electrophysiological interactions between these three subsystems during behavior remain largely unknown. We hypothesized that the striatum might be particularly active during exploratory behavior, which is presumably associated with increased attention. We investigated the modulation of local field potentials (LFPs) in the striatum during attentive wakefulness in freely moving rats. To this end, we implanted microelectrodes into different parts of the striatum of Wistar rats, as well as into the motor, associative and limbic cortices. We then used electromyograms to identify motor activity and analyzed the instantaneous frequency, power spectra and partial directed coherence during exploratory behavior. We observed fine modulation in the theta frequency range of striatal LFPs in 92.5 ± 2.5% of all epochs of exploratory behavior. Concomitantly, the theta power spectrum increased in all striatal channels (P < 0.001), and coherence analysis revealed strong connectivity (coefficients >0.7) between the primary motor cortex and the rostral part of the caudatoputamen nucleus, as well as among all striatal channels (P < 0.001). Conclusively, we observed a pattern of strong theta band activation in the entire striatum during attentive wakefulness, as well as a strong coherence between the motor cortex and the entire striatum. We suggest that this activation reflects the integration of motor, cognitive and limbic systems during attentive wakefulness.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Em conformidade com a dúvida de seu título, o difundido livro The New Brutalism: Ethic or Aesthetic? de Reyner Banham não é possível explicar o Brutalismo como manifestação artística coesa, dotada de consistência e reprodutibilidade formal. A citação de arquitetos famosos, porém divergentes, parece associar e comparar obras ásperas com a pretensão de reerguer uma arquitetura moderna considerada ascética, monótona e insuficiente e gera um teoricismo da aparência crua e do moralismo dos objetos. Discurso que oculta, ou desvia a atenção do retorno artístico à sublimidade e construção artesanal. O Brutalismo é aceito como evolução natural dos estágios modernos anteriores e sanciona artefatos toscos, pesados e inacabados como se fossem filiados ao processo moderno desinfestado. Esconde contradições e disfarça seu rompimento com o moderno para prolongar a expressão Movimento moderno. Mas o objeto claro, econômico e preciso é repudiado pelo consumidor e, por ser pouco representativo, o artista faz sua maquiagem com episódios contrastantes e monumentais na informalidade das cidades espontâneas. No entanto, parece possível suspender a noção positiva e corretiva do Brutalismo para entendê-lo como um recuo artístico vulgarizador que despreza aperfeiçoamento e afronta a atitude moderna com banalização conceptiva, exagero, figuralidade, musculação estrutural, grandeza tectônica, rudimento e rudeza. Assim, moralismo, retorno rústico e originalidade desqualificam a expressão International Style entendida como a culminação da arquitetura moderna do pós-guerra, ao depreciá-la como decadente, como produto imobiliário, comercial e corporativo a serviço do capital. Essa interpretação desvela uma crítica anti-industrial, portanto antimodernista e diversa da pós-modernidade, porém contestadora e realista para fornecer imagens à cultura e aos insensíveis à estrutura da forma moderna. Diverso da pós-modernidade pela dependência ao moderno e ausência de apelo popular. Tornada insignificante a configuração oportuna do artefato, o arquiteto tenta reter sua notabilidade artística, ou o prestígio que parece enfraquecer na aparência símile da especificação de catálogo, no rigor modular. Indispõe-se e repudia componentes, Standards e acabamentos impessoais da indústria da construção para insistir em autoria e inspiração, mas repete cacoetes estilísticos de época e o inexplicável uso intensivo de concreto bruto e aparente para sentir-se engajado e atualizado. Porém, é necessário distinguir obras de aparência severa concebidas pela atitude moderna mais autêntica das de concreto aparente em tipos ou configurações aberrantes. Para avançar na discussão do Brutalismo propõe-se entender este fenômeno com a substituição do juízo estético moderno de sentido visual postulado por Immanuel Kant (1724-1804) por um sentimento estético fácil e relacionado com a sensação da empatia, com a Einfühlung de Robert Vischer (1847-1933). Na época da cultura de massas, admite-se o rebaixamento das exigências no artefato e a adaptação brutalista com a transfiguração dos processos de arquitetura moderna. Assim, a forma é substituída pela figura ou pelo resumo material; a estrutura formal subjacente pelo ritmo e exposição da estrutura física; o reconhecimento visual pelo entusiasmo psicológico ou pelo impulso dionisíaco; a concepção substituída pelo partido, ou, ainda, pelo conceito; a sistematização e a ordem pela moldagem e a organização; a abstração e síntese pela originalidade e essencialidade, o sentido construtivo pela honestidade material; a identidade das partes pela fundição ou pela unicidade objetal e a residência pela cabana primitiva.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Abstract: Background: Nitric oxide synthase (NOS) is essential for the synthesis of nitric oxide (NO), a non-conventional neurotransmitter with an important role in synaptic plasticity underlying processes of hippocampus-dependent memory and in the regulation of biological clocks and circadian rhythms. Many studies have shown that both the NOS cytosolic protein content and its enzymatic activity present a circadian variation in different regions of the rodent brain, including the hippocampus. The present study investigated the daily variation of NOS enzymatic activity and the cytosolic content of nNOS in the hippocampus of pigeons. Results: Adult pigeons kept under a skeleton photoperiod were assigned to six different groups. Homogenates of the hippocampus obtained at six different times-of-day were used for NOS analyses. Both iNOS activity and nNOS cytosolic protein concentrations were highest during the subjective light phase and lowest in the subjective dark phase of the circadian period. ANOVA showed significant time differences for iNOS enzymatic activity (p < 0.05) and for nNOS protein content (p < 0.05) in the hippocampus. A significant daily rhythm for both iNOS and nNOS was confirmed by analysis with the Cosinor method (p < 0.05). The present findings indicate that the enzymatic activity of iNOS and content of nNOS protein in the hippocampus of pigeons exhibit a daily rhythm, with acrophase values occurring during the behavioral activity phase. Conclusions: The data corroborate the reports on circadian variation of NOS in the mammalian hippocampus and can be considered indicative of a dynamic interaction between hippocampus-dependent processes and circadian clock mechanisms.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The timing of larval release may greatly affect the survivorship and distribution of pelagic stages and reveal important aspects of life history tactics in marine invertebrates. Endogenous rhythms of breeding individuals and populations are valuable indicators of selected strategies because they are free of the neutral effect of stochastic environmental variation. The high-shore intertidal barnacle Chthamalus bisinuatus exhibits endogenous tidal and tidal amplitude rhythms in a way that larval release would more likely occur during fortnightly neap periods at high tide. Such timing would minimize larval loss due to stranding and promote larval retention close to shore. This fully explains temporal patterns in populations facing the open sea and inhabiting eutrophic areas. However, rhythmic activity breaks down to an irregular pattern in a population within the São Sebastião Channel subjected to large variation of food supply around a mesotrophic average. Peaks of chl a concentration precede release events by 6 d, suggesting resource limitation for egg production within the channel. Also, extreme daily temperatures imposing mortality risk correlate to release rate just 1 d ahead, suggesting a terminal reproductive strategy. Oceanographic conditions apparently dictate whether barnacles follow a rhythmic trend of larval release supported by endogenous timing or, alternatively, respond to the stochastic variation of key environmental factors, resulting in an erratic temporal pattern.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Background: Nitric oxide synthase (NOS) is essential for the synthesis of nitric oxide (NO), a non-conventional neurotransmitter with an important role in synaptic plasticity underlying processes of hippocampus-dependent memory and in the regulation of biological clocks and circadian rhythms. Many studies have shown that both the NOS cytosolic protein content and its enzymatic activity present a circadian variation in different regions of the rodent brain, including the hippocampus. The present study investigated the daily variation of NOS enzymatic activity and the cytosolic content of nNOS in the hippocampus of pigeons. Results: Adult pigeons kept under a skeleton photoperiod were assigned to six different groups. Homogenates of the hippocampus obtained at six different times-of-day were used for NOS analyses. Both iNOS activity and nNOS cytosolic protein concentrations were highest during the subjective light phase and lowest in the subjective dark phase of the circadian period. ANOVA showed significant time differences for iNOS enzymatic activity (p < 0.05) and for nNOS protein content (p < 0.05) in the hippocampus. A significant daily rhythm for both iNOS and nNOS was confirmed by analysis with the Cosinor method (p < 0.05). The present findings indicate that the enzymatic activity of iNOS and content of nNOS protein in the hippocampus of pigeons exhibit a daily rhythm, with acrophase values occurring during the behavioral activity phase. Conclusions: The data corroborate the reports on circadian variation of NOS in the mammalian hippocampus and can be considered indicative of a dynamic interaction between hippocampus-dependent processes and circadian clock mechanisms.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

AIMS: The circadian rhythm in mammalian pineal melatonin secretion is modulated by norepinephrine (NE) released at night. NE interaction with β1-adrenoceptors activates PKA that phosphorylates the transcription factor CREB, leading to the transcription and translation of the arylalkylamine-N-acetyltransferase (AANAT) enzyme. Several studies have reported the interplay between CREB and the nuclear factor-κB (NF-κB) and a circadian rhythm for this transcription factor was recently described in the rat pineal gland. In this work we studied a direct effect of NE on NF-κB activation and the role played by this factor on melatonin synthesis and Aanat transcription and activity. MAIN METHODS: Cultured rat pineal glands were incubated in the presence of two different NF-κB inhibitors, pyrrolidine-dithiocarbamate or sodium salicylate, and stimulated with NE. Melatonin content was quantified by HPLC with electrochemical detection. AANAT activity was measured by a radiometric assay and the expression of Aanat mRNA was analyzed by real-time PCR. Gel shift assay was performed to study the NF-κB activation in cultured rat pineal glands stimulated by NE. KEY FINDINGS: Our results showed that the p50/p50 homodimer of NF-κB is activated by NE and that it has a role in melatonin synthesis, acting on Aanat transcription and activity. SIGNIFICANCE: Here we present evidence that NF-κB is an important transcription factor that acts, directly or indirectly, on Aanat transcription and activity leading to a modulation of melatonin synthesis. NE plays a role in the translocation of NF-κB p50/p50 homodimer to the nucleus of pinealocytes, thus probably influencing the nocturnal pineal melatonin synthesis

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Estudo transversal que avaliou a qualidade dos registros de enfermagem sobre ressuscitação cardiopulmonar. Foram revisados 42 prontuários de pacientes em uma unidade de terapia intensiva, utilizando o protocolo Utstein. Houve predomínio de homens (54,8%), idade de 21 a 70 anos (38,1%), correção de cardiopatias adquiridas (42,7%), com mais de um dispositivo pré-existente (147). Como causa imediata de parada cardiorrespiratória, predominou hipotensão (48,3%) e como ritmo inicial, bradicardia (37,5%). Apenas a hora do óbito e hora da parada foram registradas em 100% da amostra. Não foi registrado treinamento dos profissionais em Suporte Avançado de Vida. As causas da parada e ritmo inicial foram registrados em 69% e 76,2% da amostra. Compressões torácicas, obtenção de vias aéreas pérvias e desfibrilação foram registradas em menos de 16%. Os registros foram considerados de baixa qualidade, podendo incorrer em sanções legais aos profissionais e não permitindo a comparação da efetividade das manobras com outros centros.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

[ES] Aplicación para dispositivos móviles Android que, ayudada por acelerómetros y giroscopios, da soporte al desarrollo de actividades físicas que necesiten un plan de trabajo basado en repeticiones y rutinas de ejercicios. El App ayuda a contabilizar las repeticiones de cada ejercicio, informando al usuario mediante sonido, para que este pueda mantener un ritmo continuo. El App permite la realización de ejercicios individuales hasta alcanzar un número objetivo de repeticiones o repeticiones libres; o permite la realización de una serie de ejercicios que forman parte de una rutina de ejercicios. Es posible crear rutinas de ejercicios personalizadas, eliminar rutinas o editar rutinas ya existentes (añadiendo o eliminando ejercicios y repeticiones). El reconocimiento de movimientos para la contabilización de repeticiones se realiza usando el valor absoluto del vector de aceleración generado a partir de los datos del acelerómetro del dispositivo. Este método, aunque no permite la precisión de reconocimiento de movimientos que permitiría el modelado tridimensional de la aceleración lineal del dispositivo, permite un reconocimiento menos computacionalmente costoso, ignorando ciertos factores exteriores y sin la necesidad de entrenamiento previo de la aplicación.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The cardiovascular regulation undergoes wide changes in the different states of sleepwake cycle. In particular, the relationship between spontaneous fluctuations in heart period and arterial pressure clearly shows differences between the two sleep states. In non rapid-eye-movement sleep, heart rhythm is under prevalent baroreflex control, whereas in rapid-eye-movement sleep central autonomic commands prevail (Zoccoli et al., 2001). Moreover, during rapid-eye-movement sleep the cardiovascular variables show wide fluctuations around their mean value. In particular, during rapid-eyemovement sleep, the arterial pressure shows phasic hypertensive events which are superimposed upon the tonic level of arterial pressure. These phasic increases in arterial pressure are accompanied by an increase in heart rate (Sei & Morita, 1996; Silvani et al., 2005). Thus, rapid-eye-movement sleep may represent an “autonomic stress test” for the cardiovascular system, able to unmask pathological patterns of cardiovascular regulation (Verrier et al. 2005), but this hypothesis has never been tested experimentally. The aim of this study was to investigate whether rapid-eye-movement sleep may reveal derangements in central autonomic cardiovascular control in an experimental model of essential hypertension. The study was performed in Spontaneously Hypertensive Rats, which represent the most widely used model of essential hypertension, and allow full control of genetic and environmental confounding factors. In particular, we analyzed the cardiovascular, electroencephalogram, and electromyogram changes associated with phasic hypertensive events during rapid-eyemovement sleep in Spontaneously Hypertensive Rats and in their genetic Wistar Kyoto control strain. Moreover, we studied also a group of Spontaneously Hypertensive Rats made phenotypically normotensive by means of a chronic treatment with an angiotensin converting enzyme inhibitor, the Enalapril maleate, from the age of four weeks to the end of the experiment. All rats were implanted with electrodes for electroencephalographic and electromyographic recordings and with an arterial catheter for arterial pressure measurement. After six days for postoperative recovery, the rats were studied for five days, at an age of ten weeks.The study indicated that the peak of mean arterial pressure increase during the phasic hypertensive events in rapid-eye-movement sleep did not differ significantly between Spontaneously Hypertensive Rats and Wistar Kyoto rats, while on the other hand Spontaneously Hypertensive Rats showed a reduced increase in the frequency of theta rhythm and a reduced tachicardia with respect to Wistar Kyoto rats. The same pattern of changes in mean arterial pressure, heart period, and theta frequency was observed between Spontaneously Hypertensive Rats and Spontaneously Hypertensive Rats treated with Enalapril maleate. Spontaneously Hypertensive Rats do not differ from Wistar Kyoto rats only in terms of arterial hypertension, but also due to multiple unknown genetic differences. Spontaneously Hypertensive Rats were developed by selective breeding of Wistar Kyoto rats based only on the level of arterial pressure. However, in this process, multiple genes possibly unrelated to hypertension may have been selected together with the genetic determinants of hypertension (Carley et al., 2000). This study indicated that Spontaneously Hypertensive Rats differ from Wistar Kyoto rats, but not from Spontaneously Hypertensive Rats treated with Enalapril maleate, in terms of arterial pH and theta frequency. This feature may be due to genetic determinants unrelated to hypertension. In sharp contrast, the persistence of differences in the peak of heart period decrease and the peak of theta frequency increase during phasic hypertensive events between Spontaneously Hypertensive Rats and Spontaneously Hypertensive Rats treated with Enalapril maleate demonstrates that the observed reduction in central autonomic control of the cardiovascular system in Spontaneously Hypertensive Rats is not an irreversible consequence of inherited genetic determinants. Rather, the comparison between Spontaneously Hypertensive Rats and Spontaneously Hypertensive Rats treated with Enalapril maleate indicates that the observed differences in central autonomic control are the result of the hypertension per se. This work supports the view that the study of cardiovascular regulation in sleep provides fundamental insight on the pathophysiology of hypertension, and may thus contribute to the understanding of this disease, which is a major health problem in European countries (Wolf-Maier et al., 2003) with its burden of cardiac, vascular, and renal complications.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

My work is focused on George Friel, a distinguished Scottish writer known for his witty style bristling with puns and more or less literary allusions. In particular I proposed an annotated translation of what can be considered his masterpiece “Mr Alfred M.A.” in which wordplay has a central role for its plot. In the first part of my thesis I outlined the fundamental features of Friel’s writing: the wide variety of registers and styles, the rhythm and irony. Additionally I pointed out the strategies that the translator has to face when translating this text. Finally I identified the number of problems which may arise while translating Friel’s “Mr Alfred M.A.” into Italian with particular concern on the strategies of supplementation and explicitation for wordplay.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

I Max Bill is an intense giornata of a big fresco. An analysis of the main social, artistic and cultural events throughout the twentieth century is needed in order to trace his career through his masterpieces and architectures. Some of the faces of this hypothetical mural painting are, among others, Le Corbusier, Walter Gropius, Ernesto Nathan Rogers, Kandinskij, Klee, Mondrian, Vatongerloo, Ignazio Silone, while the backcloth is given by artistic avant-gardes, Bauhaus, International Exhibitions, CIAM, war events, reconstruction, Milan Triennali, Venice Biennali, the School of Ulm. Architect, even though more known as painter, sculptor, designer and graphic artist, Max Bill attends the Bauhaus as a student in the years 1927-1929, and from this experience derives the main features of a rational, objective, constructive and non figurative art. His research is devoted to give his art a scientific methodology: each work proceeds from the analysis of a problem to the logical and always verifiable solution of the same problem. By means of composition elements (such as rhythm, seriality, theme and its variation, harmony and dissonance), he faces, with consistent results, themes apparently very distant from each other as the project for the H.f.G. or the design for a font. Mathematics are a constant reference frame as field of certainties, order, objectivity: ‘for Bill mathematics are never confined to a simple function: they represent a climate of spiritual certainties, and also the theme of non attempted in its purest state, objectivity of the sign and of the geometrical place, and at the same time restlessness of the infinity: Limited and Unlimited ’. In almost sixty years of activity, experiencing all artistic fields, Max Bill works, projects, designs, holds conferences and exhibitions in Europe, Asia and Americas, confronting himself with the most influencing personalities of the twentieth century. In such a vast scenery, the need to limit the investigation field combined with the necessity to address and analyse the unpublished and original aspect of Bill’s relations with Italy. The original contribution of the present research regards this particular ‘geographic delimitation’; in particular, beyond the deep cultural exchanges between Bill and a series of Milanese architects, most of all with Rogers, two main projects have been addressed: the realtà nuova at Milan Triennale in 1947, and the Contemporary Art Museum in Florence in 1980. It is important to note that these projects have not been previously investigated, and the former never appears in the sources either. These works, together with the most well-known ones, such as the projects for the VI and IX Triennale, and the Swiss pavilion for the Biennale, add important details to the reference frame of the relations which took place between Zurich and Milan. Most of the occasions for exchanges took part in between the Thirties and the Fifties, years during which Bill underwent a significant period of artistic growth. He meets the Swiss progressive architects and the Paris artists from the Abstraction-Création movement, enters the CIAM, collaborates with Le Corbusier to the third volume of his Complete Works, and in Milan he works and gets confronted with the events related to post-war reconstruction. In these years Bill defines his own working methodology, attaining an artistic maturity in his work. The present research investigates the mentioned time period, despite some necessary exceptions. II The official Max Bill bibliography is naturally wide, including spreading works along with ones more devoted to analytical investigation, mainly written in German and often translated into French and English (Max Bill himself published his works in three languages). Few works have been published in Italian and, excluding the catalogue of the Parma exhibition from 1977, they cannot be considered comprehensive. Many publications are exhibition catalogues, some of which include essays written by Max Bill himself, some others bring Bill’s comments in a educational-pedagogical approach, to accompany the observer towards a full understanding of the composition processes of his art works. Bill also left a great amount of theoretical speculations to encourage a critical reading of his works in the form of books edited or written by him, and essays published in ‘Werk’, magazine of the Swiss Werkbund, and other international reviews, among which Domus and Casabella. These three reviews have been important tools of analysis, since they include tracks of some of Max Bill’s architectural works. The architectural aspect is less investigated than the plastic and pictorial ones in all the main reference manuals on the subject: Benevolo, Tafuri and Dal Co, Frampton, Allenspach consider Max Bill as an artist proceeding in his work from Bauhaus in the Ulm experience . A first filing of his works was published in 2004 in the monographic issue of the Spanish magazine 2G, together with critical essays by Karin Gimmi, Stanislaus von Moos, Arthur Rüegg and Hans Frei, and in ‘Konkrete Architektur?’, again by Hans Frei. Moreover, the monographic essay on the Atelier Haus building by Arthur Rüegg from 1997, and the DPA 17 issue of the Catalonia Polytechnic with contributions of Carlos Martì, Bruno Reichlin and Ton Salvadò, the latter publication concentrating on a few Bill’s themes and architectures. An urge to studying and going in depth in Max Bill’s works was marked in 2008 by the centenary of his birth and by a recent rediscovery of Bill as initiator of the ‘minimalist’ tradition in Swiss architecture. Bill’s heirs are both very active in promoting exhibitions, researching and publishing. Jakob Bill, Max Bill’s son and painter himself, recently published a work on Bill’s experience in Bauhaus, and earlier on he had published an in-depth study on ‘Endless Ribbons’ sculptures. Angela Thomas Schmid, Bill’s wife and art historian, published in end 2008 the first volume of a biography on Max Bill and, together with the film maker Eric Schmid, produced a documentary film which was also presented at the last Locarno Film Festival. Both biography and documentary concentrate on Max Bill’s political involvement, from antifascism and 1968 protest movements to Bill experiences as Zurich Municipality councilman and member of the Swiss Confederation Parliament. In the present research, the bibliography includes also direct sources, such as interviews and original materials in the form of letters correspondence and graphic works together with related essays, kept in the max+binia+jakob bill stiftung archive in Zurich. III The results of the present research are organized into four main chapters, each of them subdivided into four parts. The first chapter concentrates on the research field, reasons, tools and methodologies employed, whereas the second one consists of a short biographical note organized by topics, introducing the subject of the research. The third chapter, which includes unpublished events, traces the historical and cultural frame with particular reference to the relations between Max Bill and the Italian scene, especially Milan and the architects Rogers and Baldessari around the Fifties, searching the themes and the keys for interpretation of Bill’s architectures and investigating the critical debate on the reviews and the plastic survey through sculpture. The fourth and last chapter examines four main architectures chosen on a geographical basis, all devoted to exhibition spaces, investigating Max Bill’s composition process related to the pictorial field. Paintings has surely been easier and faster to investigate and verify than the building field. A doctoral thesis discussed in Lausanne in 1977 investigating Max Bill’s plastic and pictorial works, provided a series of devices which were corrected and adapted for the definition of the interpretation grid for the composition structures of Bill’s main architectures. Four different tools are employed in the investigation of each work: a context analysis related to chapter three results; a specific theoretical essay by Max Bill briefly explaining his main theses, even though not directly linked to the very same work of art considered; the interpretation grid for the composition themes derived from a related pictorial work; the architecture drawing and digital three-dimensional model. The double analysis of the architectural and pictorial fields is functional to underlining the relation among the different elements of the composition process; the two fields, however, cannot be compared and they stay, in Max Bill’s works as in the present research, interdependent though self-sufficient. IV An important aspect of Max Bill production is self-referentiality: talking of Max Bill, also through Max Bill, as a need for coherence instead of a method limitation. Ernesto Nathan Rogers describes Bill as the last humanist, and his horizon is the known world but, as the ‘Concrete Art’ of which he is one of the main representatives, his production justifies itself: Max Bill not only found a method, but he autonomously re-wrote the ‘rules of the game’, derived timeless theoretical principles and verified them through a rich and interdisciplinary artistic production. The most recurrent words in the present research work are synthesis, unity, space and logic. These terms are part of Max Bill’s vocabulary and can be referred to his works. Similarly, graphic settings or analytical schemes in this research text referring to or commenting Bill’s architectural projects were drawn up keeping in mind the concise precision of his architectural design. As for Mies van der Rohe, it has been written that Max Bill took art to ‘zero degree’ reaching in this way a high complexity. His works are a synthesis of art: they conceptually encompass all previous and –considered their developments- most of contemporary pictures. Contents and message are generally explicitly declared in the title or in Bill’s essays on his artistic works and architectural projects: the beneficiary is invited to go through and re-build the process of synthesis generating the shape. In the course of the interview with the Milan artist Getulio Alviani, he tells how he would not write more than a page for an essay on Josef Albers: everything was already evident ‘on the surface’ and any additional sentence would be redundant. Two years after that interview, these pages attempt to decompose and single out the elements and processes connected with some of Max Bill’s works which, for their own origin, already contain all possible explanations and interpretations. The formal reduction in favour of contents maximization is, perhaps, Max Bill’s main lesson.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Objective: To study circadian rhythms (sleep-wake, body core temperature and melatonin circadian rhythms) in patients in vegetative state (VS) in basal condition and after nocturnal blue light exposure. Methods: Eight patients in VS underwent two experimental sessions of 48 consecutive hours polysomnography with body core temperature (BCT) measurement separated by a 1-week interval. For a week between the two experimental sessions, patients underwent nocturnal blue light exposure (470 nm; 58 μW/cm2 for 4 hours from 11.30 p.m. to 3.30 a.m.). Brain MRI, Level of Cognitive Functioning Scale (LCF) and Disability Rating Scale (DRS) were assessed just before polysomnography. Results: In all patients LCF and DRS confirmed vegetative state. All patients showed a sleep-wake cycle. All patients showed spindle or spindle-like activities. REM sleep was detected in only 7 patients. Patients displayed a greater fragmentation of nocturnal sleep due to frequent awakenings. Mean nocturnal sleep efficiency was significantly reduced (40±22 vs. 74±17) in VS patients respect to controls. A significantly increasing of phase 1 and a significantly reduction of phase 2 and phase 3 were observed too. A modification of diurnal sleep total time and of diurnal duration of REM sleep were found after 1-week nocturnal blue light exposure. All patients displayed a normal BCT 24-h rhythm in basal condition and after nocturnal blue light exposure. A reduction of mean nocturnal melatonin levels in basal condition were observed in VS patients. Melatonin suppression after blue light exposure was observed in only 2 patients in VS. Conclusions: We found disorganized sleep-wake cycle and a normal BCT rhythm in our patients in VS. A reduction of mean nocturnal melatonin levels in basal condition were observed too.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

During the wake sleep (W-S) cycle in mammals, the alternation of the different states, wake, NREM sleep (NREMS) and REM sleep (REMS), is associated not only with electroencephalographic or behavioural changes, but also with modifications in the physiological regulations of the organism. The most evident change is the existence of a suspension of the somatic and autonomic thermoregulatory responses during REMS. Since thermoregulation is prevalently controlled by the Preoptic Area-Anterior Hypothalamus (PO-AH), its suspension during REM sleep has been taken as a sign of an impairment of the hypothalamic integrative activity that could explain the modifications in physiological regulation observed in this sleep stage. The recent finding from our laboratory that the secretion of the antidiuretic hormone arginine-vasopressin (AVP) in response to a central osmotic stimulation is quantitatively the same throughout the different stages of the W-S cycle, has shown that hypothalamic osmoregulation is not suspended during REMS. In order to clarify the extent of the hypothalamic involvement in the regulation of the W-S cycle, we have studied the effects of three days of water deprivation and of two days of recovery during which animals were allowed a free access to water, on the architecture of the W-S cycle. The condition of water deprivation represents a severe challenge involving neuroendocrine and autonomic hypothalamic regulations. In contradiction with thermoregulatory studies, in which it has been clearly demonstrated that a thermal challenge selectively reduces REMS occurrence, the results of this study show that REMS occurrence is mildly reduced only in the third day of water deprivation. The most striking effects produced by water deprivation appear to concern NREMS, which shows a selective and significant reduction in its slow EEG activity (delta-power) but not in its duration. The recovery period is mainly characterized by a disruption of the normal circadian rhythm of REMS occurrence and by a rebound of the delta power in NREMS. Thus, an autonomic challenge different from those related to thermoregulation and an endocrine challenge as the continuous secretion of AVP show to exert different effects on the stages of the wake-sleep cycle. Also, this study demonstrates that the impairment of the hypothalamic integrative activity thought to characterize the occurrence of REMS only involves thermoregulatory structures.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Ventricular cells are immersed in a bath of electrolytes and these ions are essential for a healthy heart and a regular rhythm. Maintaining physiological concentration of them is fundamental for reducing arrhythmias and risk of sudden cardiac death, especially in haemodialysis patients and in the heart diseases treatments. Models of electrically activity of the heart based on mathematical formulation are a part of the efforts to improve the understanding and prediction of heart behaviour. Modern models incorporate the extensive and ever increasing amounts of experimental data in incorporating biophysically detailed mechanisms to allow the detailed study of molecular and subcellular mechanisms of heart disease. The goal of this project was to simulate the effects of changes in potassium and calcium concentrations in the extracellular space between experimental data and and a description incorpored into two modern biophysically detailed models (Grandi et al. Model; O’Hara Rudy Model). Moreover the task was to analyze the changes in the ventricular electrical activity, in particular by studying the modifications on the simulated electrocardiographic signal. We used the cellular information obtained by the heart models in order to build a 1D tissue description. The fibre is composed by 165 cells, it is divided in four groups to differentiate the cell types that compound human ventricular tissue. The main results are the following: Grandi et al. (GBP) model is not even able to reproduce the correct action potential profile in hyperkalemia. Data from hospitalized patients indicates that the action potential duration (APD) should be shorter than physiological state but in this model we have the opposite. From the potassium point of view the results obtained by using O’Hara model (ORD) are in agreement with experimental data for the single cell action potential in hypokalemia and hyperkalemia, most of the currents follow the data from literature. In the 1D simulations we were able to reproduce ECGs signal in most the potassium concentrations we selected for this study and we collected data that can help physician in understanding what happens in ventricular cells during electrolyte disorder. However the model fails in the conduction of the stimulus under hyperkalemic conditions. The model emphasized the ECG modifications when the K+ is slightly more than physiological value. In the calcium setting using the ORD model we found an APD shortening in hypocalcaemia and an APD lengthening in hypercalcaemia, i.e. the opposite to experimental observation. This wrong behaviour is kept in one dimensional simulations bringing a longer QT interval in the ECG under higher [Ca2+]o conditions and vice versa. In conclusion it has highlighted that the actual ventricular models present in literature, even if they are useful in the original form, they need an improvement in the sensitivity of these two important electrolytes. We suggest an use of the GBP model with modifications introduced by Carro et al. who understood that the failure of this model is related to the Shannon et al. model (a rabbit model) from which the GBP model was built. The ORD model should be modified in the Ca2+ - dependent IcaL and in the influence of the Iks in the action potential for letting it him produce a correct action potential under different calcium concentrations. In the 1D tissue maybe a heterogeneity setting of intra and extracellular conductances for the different cell types should improve a reproduction of the ECG signal.