Patients with schizophrenia have a higher risk of cardiovascular diseases and higher mortality from them than does the general population; however, the underlying mechanism remains unclear. Impaired cerebral autoregulation is associated with cerebrovascular diseases and their mortality. Increased or decreased cerebral blood flow in different brain regions has been reported in patients with schizophrenia, which implies impaired cerebral autoregulation. This study investigated the cerebral autoregulation in 21 patients with schizophrenia and 23 age- and sex-matched healthy controls. None of (...) the participants had a history of cardiovascular diseases, hypertension, or diabetes. All participants underwent 10-min blood pressure and cerebral blood flow recording through finger plethysmography and Doppler ultrasonography, respectively. Cerebral autoregulation was assessed by analyzing two autoregulation indices: the mean blood pressure and cerebral blood flow correlation coefficient (Mx), and the phase shift between the waveforms of blood pressure and cerebral blood flow determined using transfer function analysis. Compared with the controls, the patients had a significantly higher Mx (0.257 vs. 0.399, p = 0.036) and lower phase shift (44.3° vs. 38.7° in the 0.07–0.20 Hz frequency band, p = 0.019), which indicated impaired maintenance of constant cerebral blood flow and a delayed cerebrovascular autoregulatory response. Impaired cerebral autoregulation may be caused by schizophrenia and may not be an artifact of coexisting medical conditions. The mechanism underlying impaired cerebral autoregulation in schizophrenia and its probable role in the development of cerebrovascular diseases require further investigation. (shrink)

We have studied a number of long-term meditators in previous studies. The purpose of this study was to determine if there are differences in baseline brain function of experienced meditators compared to non-meditators. All subjects were recruited as part of an ongoing study of different meditation practices. We evaluated 12 advanced meditators and 14 non-meditators with cerebral blood flow SPECT imaging at rest. Images were analyzed with both region of interest and statistical parametric mapping. The CBF of long-term (...) meditators was significantly higher compared to non-meditators in the prefrontal cortex, parietal cortex, thalamus, putamen, caudate, and midbrain. There was also a significant difference in the thalamic laterality with long-term meditators having greater asymmetry. The observed changes associated with long-term meditation appear in structures that underlie the attention network and also those that relate to emotion and autonomic function. (shrink)

Modern readers view ancient theories of blood flow through the lens of circulation. Since the nineteenth century, scholarly work on the ancient understanding of the vascular system has run the gamut from attempting to prove that an ancient author had in fact, to some extent or another, pre-empted Harvey's discovery of the circulation of the blood or towards attempting, often with some empathetic embarrassment, to explain the failure on the part of an ancient author to notice something (...) that seems so obvious to the modern eye. Thus C.R.S. Harris's 1973 book The Heart and Vascular System in Ancient Greek Medicine, which remains the standard on the topic, opens with a sentence in which he marvels at how the otherwise admirable ancient Greek physicians could have ‘failed entirely to arrive at any conception of the circulation of the blood’. This modern vantage point has had an unfortunate effect. In the case of Aristotle in particular, understanding of his cardiovascular system has been diminished by a tendency to define it in contradistinction to our own modern understanding of circulation. By deliberately uncoupling from the framework of modern physiology, this paper will offer a richer and more accurate picture of his views. (shrink)

This article combines in-depth interviews and Karen Barad's work on materiality to think about the ways in which the materiality of blood might be understood in relation to sociality and blood-borne virus prevention among BDSM (bondage and domination, dominance and submission and sadomasochism) body modification practitioners in Sydney, Australia. In doing so, it confronts questions of how the materiality of blood can be theorized in ways that neither presume a fixed, a priori ontological status or essence, nor (...) exclude it from an active role in the production of realities. In taking account of both its co-constitutive role in practice, and its figurative power (as flow) in understanding the mind/body, discourse/materiality conjunctions at work in BDSM body modification practice, we aim to illuminate further the imbrication of materiality and meaning, and generate a more complex and fruitful account of blood for the purposes of blood-borne virus prevention and education. (shrink)

Aircraft with increasingly high performance were important to the war effort in World War II. Changes in technology allowed aircraft to reach faster speeds and to complete missions at higher altitudes. With these changes came new obstacles for pilots who had to tolerate these stresses. Of primary concern to the U.S. War Department was the loss of consciousness that often occurred with high-speed maneuvers and especially during pull-up after dive-bombing missions. In some cases, pilots would experience up to 9G of (...) force during rapid ascent, much more than the 6G threshold that typically leads to loss of consciousness. In 1941, a research team in Red Wing, MN, proposed experiments to elucidate the mechanism .. (shrink)

Experiential and behavioural aspects of emotions can be measured readily but developing a contactless measure of emotions’ physiological aspects has been a major challenge. We hypothesised that different emotion-evoking films can produce distinctive facial blood flow patterns that can serve as physiological signatures of discrete emotions. To test this hypothesis, we created a new Transdermal Optical Imaging system that uses a conventional video camera to capture facial blood flows in a contactless manner. Using this and deep machine (...) learning, we analysed videos of the faces of people as they viewed film clips that elicited joy, sadness, disgust, fear or a neutral state. We found that each of these elicited a distinct blood flow pattern in the facial epidermis, and that Transdermal Optical Imaging is an effective contactless and inexpensive tool to the reveal physiological correlates of discrete emotions. (shrink)

Concepts and experimental results taken frombehavioral pharmacology, functional brain imaging,brain physiology, and behavioral neuroscience, wereused to develop the hypothesis that behavioraltolerance can, in part, be attributed to cellulartolerance. It is argued that task specific activationof circumscribed neuronal populations gives rise tocorresponding increases in regional cerebral bloodflow such that neurons related to task performance areexposed to higher effective doses of blood-borne drugthan neuronal groups not highly activated by thebehavioral task. Through this cerebral hemodynamicregulatory mechanism cellular tolerance phenomena canat least partially (...) account for behavioral tolerance(i.e., tolerance conferred through drugged practice). (shrink)

BACKGROUND: Through their action on the locus coeruleus, ␣ 2-adrenoceptor agonists induce rapidly reversible sedation while partially preserving cognitive brain functions. Our goal in this observational study was to map brain regions whose activity is modified by clonidine infusion so as to better understand its loci of action, especially in relation to sedation. METHODS: Six ASA I–II right-handed volunteers were recruited. Electroencephalogram (EEG) was monitored continuously. After a baseline H215O activation scan, clonidine infusion was started at a rate ranging from (...) 6 to 10 ␮g ⅐ kgϪ1 ⅐ h Ϫ1. A sequence of 11 similar scans was then performed at 8 min intervals. Plasma clonidine concentration was measured. Using statistical parametric mapping, we sought linear correlations between normalized regional cerebral blood flow (rCBF), an indicator of regional brain activity, and plasma clonidine concentration or spindle EEG activity. RESULTS: Clonidine induced clinical sedation and EEG patterns (spindles) comparable to early stage nonrapid eye movement sleep. A significant negative linear correlation between clonidine concentration and rCBF or spindle activity was observed in the thalamus, prefrontal, orbital and parietal association cortex, posterior cingulate cortex, and precuneus. CONCLUSIONS: The EEG patterns and decreases in rCBF of specific brain regions observed during clonidine-induced sedation are similar to those of early stage nonrapid eye movement sleep. Patterns of deactivated brain regions are also comparable to those observed during general anesthesia or vegetative state, reinforcing the hypothesis that alterations in the activity of a common network occur during these modified conscious states. (shrink)

Ischemic stroke involves numerous and complex pathophysiological mechanisms including blood flow reduction, ionic exchanges, spreading depressions and cell death through necrosis or apoptosis. We used a mathematical model based on these phenomena to study the influences of intensity and duration of ischemia on the final size of the infarcted area. This model relies on a set of ordinary and partial differential equations. After a sensibility study, the model was used to carry out in silico experiments in various ischemic (...) conditions. The simulation results show that the proportion of apoptotic cells increases when the intensity of ischemia decreases, which contributes to the model validation. The simulation results also show that the influence of ischemia duration on the infarct size is more complicated. They suggest that reperfusion is beneficial when performed in the early stroke but may be either inefficacious or even deleterious when performed later after the stroke onset. This aggravation could be explained by the depolarisation waves which might continue to spread ischemic damage and by the speeding up of the apoptotic process leading to cell death. The effect of reperfusion on cell death through these two phenomena needs to be further studied in order to develop new therapeutic strategies for stroke patients. (shrink)

In this paper I first address what I consider a central issue in the account of perception in Plato’s Timaeus, namely, how the pathemata pass through the body to reach the soul, and thus become aistheseis. My point in Section 1 is that in tackling this issue Plato aims to provide a firm physiological basis to the notion of perception that starts to emerge in the Theaetetus and the Philebus and is crucial to the late development of his theory of (...) cognition. In the ensuing section I try to put the account of perception in the Timaeus into a historical perspective, aiming to highlight two points: a) Plato’s description of the way in which sensible impressions “travel” inside the body and interact with its parts and other constituents is largely indebted to previous theories, such as those we find, for example, in Empedocles and a few Hippocratic writers; b) The leading role in this story (where internal air plays a significant supporting role) is played by blood flowing through the vascular system and thus performing a crucial cognitive function. Moreover, emphasizing the role of blood as well as analyzing the elaborate way in which perceptions are transmitted through the body to the soul proves vital to appreciate (in Section 3) the cognitive status of the lower parts of the soul (which are more involved in perception) and their relation to reason. Overall, the paper adds further elements to our understanding of Plato’s embodied approach to cognition. I had already written (and submitted) this article when Johansen (2021) was published. The latter’s approach to the role of blood in Plato’s physiology of knowledge in the Timaeus converges in part with mine (as I was pleased to find out), partly due to our overlapping sources and bibliography. (shrink)

The subject of this paper is Georg Ernst Stahl's reflections on epilepsy. In the German physician's work, the concept of disease is stratified: it is the morbid idea which causes dysfunctions in the animal economy, as well as irregular motion, overabundance and ultimately an alteration of the corporeal humours. In particular, epilepsy is an affection deriving from an altered functioning of the bodily motions, caused by abnormal blood flow, intestinal worms, anatomical defects, foreign bodies, and the passions of (...) the soul. While a certain medical tradition attributed a nervous origin to epilepsy, Stahl, giving it a humoural genesis, openly shows the theoretical premises on which his physiology rests. So, Stahlian physiology appears to be a non-mechanistic, teleological-inspired, hydraulicism. (shrink)

. The subject of this paper is Georg Ernst Stahl's reflections on epilepsy. In the German physician's work, the concept of disease is stratified: it is the morbid idea which causes dysfunctions in the animal economy, as well as irregular motion, overabundance and ultimately an alteration of the corporeal humours. In particular, epilepsy is an affection deriving from an altered functioning of the bodily motions, caused by abnormal blood flow, intestinal worms, anatomical defects, foreign bodies, and the passions (...) of the soul. While a certain medical tradition attributed a nervous origin to epilepsy, Stahl, giving it a humoural genesis, openly shows the theoretical premises on which his physiology rests. So, Stahlian physiology appears to be a non-mechanistic, teleological-inspired, hydraulicism. (shrink)

Brain mapping studies using dynamic imaging methods demonstrate areas regional cerebral blood flow (rCBF) decreases, as well as areas where increases, during performance of various experimental tasks. Task holds for both sets of cerebral blood flow changes (CBF), providing the opportunity to investigate areas that become and “activated” in the experimental condition relative to control state. Such data yield the intriguing observation that in areas in emotional processing, such as the amygdala, the posteromedial cortex, and the (...) ventral anterior cingulate cortex, although flow as expected during specific emotion-related tasks, flow decreases performance of some attentionally demanding, cognitive tasks. Conversely, in some of the areas that appear to subserve cognitive functions, as the dorsal anterior cingulate and the dorsolateral prefrontal cortices, increases while performing attentionally demanding cognitive tasks, but during some experimentally induced and pathological emotional Although the specific nature of such reciprocal patterns of regional remains unclear, they may reflect an important cross-modal interaction during mental operations. The possibility that neural activity is less in areas required in emotional processing during some higher cognitive processes holds implications for the mechanisms underlying interactions cognition and emotion. Furthermore, the possibility that neural in some cognitive-processing areas is suppressed during intense states suggests mechanisms by which extreme fear or severe may interfere with cognitive performance. (shrink)

Brain mapping studies using dynamic imaging methods demonstrate areas regional cerebral blood flow (rCBF) decreases, as well as areas where increases, during performance of various experimental tasks. Task holds for both sets of cerebral blood flow changes (CBF), providing the opportunity to investigate areas that become and “activated” in the experimental condition relative to control state. Such data yield the intriguing observation that in areas in emotional processing, such as the amygdala, the posteromedial cortex, and the (...) ventral anterior cingulate cortex, although flow as expected during specific emotion-related tasks, flow decreases performance of some attentionally demanding, cognitive tasks. Conversely, in some of the areas that appear to subserve cognitive functions, as the dorsal anterior cingulate and the dorsolateral prefrontal cortices, increases while performing attentionally demanding cognitive tasks, but during some experimentally induced and pathological emotional Although the specific nature of such reciprocal patterns of regional remains unclear, they may reflect an important cross-modal interaction during mental operations. The possibility that neural activity is less in areas required in emotional processing during some higher cognitive processes holds implications for the mechanisms underlying interactions cognition and emotion. Furthermore, the possibility that neural in some cognitive-processing areas is suppressed during intense states suggests mechanisms by which extreme fear or severe may interfere with cognitive performance. (shrink)

The first of its kind, this book is an in-depth history of hydrodynamics from its eighteenth-century foundations to its first major successes in twentieth-century hydraulics and aeronautics. It documents the foundational role of fluid mechanics in developing a new mathematical physics. It gives full and clear accounts of the conceptual breakthroughs of physicists and engineers who tried to meet challenges in the practical worlds of hydraulics, navigation, blood circulation, meteorology, and aeronautics, and it shows how hydrodynamics at last began (...) to fulfill its early promise to unify the different worlds of flow. Richly illustrated, technically thorough, and sensitive to cross-cultural effects, this history should attract a broad range of historians, scientists, engineers, and philosophers and be a standard reference for anyone interested in fluid mechanics. (shrink)

This paper is an analysis of the symbolism of blood in Lucan’s epic poem Bellum Civile . The first part of the article discusses several examples that show Lucan’s interest in the value that blood has when it is flowing inside someone’s body, and conversely the loss of that value when the blood is shed in battle. It then reveals a parallel between the unusual descriptions of the flow of blood, and the more usual descriptions (...) of the natural flow of water. Various examples of this parallel suggest that Lucan develops a striking image of the bloodshed of Romans becoming as normal as natural phenomena. This bloodshed thus represents the inevitable death of Rome caused by this civil war, since Lucan subtly suggests that the bloodshed and death of individual Romans only translates into the bloodshed and death of Rome itself after the main battle of this war. The theory advanced by this paper can add to the theories of some recent scholarship on this poem, which generally argues that Lucan is not so optimistic about the future of Rome as was once believed. (shrink)

This paper is an analysis of the symbolism of blood in Lucan’s epic poem Bellum Civile. The first part of the article discusses several examples that show Lucan’s interest in the value that blood has when it is flowing inside someone’s body, and conversely the loss of that value when the blood is shed in battle. It then reveals a parallel between the unusual descriptions of the flow of blood, and the more usual descriptions of (...) the natural flow of water. Various examples of this parallel suggest that Lucan develops a striking image of the bloodshed of Romans becoming as normal as natural phenomena. This bloodshed thus represents the inevitable death of Rome caused by this civil war, since Lucan subtly suggests that the bloodshed and death of individual Romans only translates into the bloodshed and death of Rome itself after the main battle of this war. The theory advanced by this paper can add to the theories of some recent scholarship on this poem, which generally argues that Lucan is not so optimistic about the future of Rome as was once believed. (shrink)

The present study addresses the fluid transport behaviour of the flow of gold -copper /biomagnetic blood hybrid nanofluid in an inclined irregular stenosis artery as a consequence of varying viscosity and Lorentz force. The nonlinear flow equations are transformed into dimensionless form by using nonsimilar variables. The finite-difference technique is involved in computing the nonlinear transport dimensionless equations. The significant parameters like angle parameter, the Hartmann number, changing viscosity, constant heat source, the Reynolds number, and nanoparticle volume (...) fraction on the flow field are exhibited through figures. Present results disclose that the Lorentz force strongly lessens the hybrid nanofluid velocity. Elevating the Grashof number values enhances the rate of blood flow. Growing values of the angle parameter cause to reduce the resistance impedance on the wall. Hybrid nanoparticles have a superior wall shear stress than copper nanoparticles. The heat transfer rate is amplifying at the axial direction with the growing values of nanoparticles concentration. The applied Lorentz force significantly reduces the hybrid and unitary nanofluid flow rate in the axial direction. The hybrid nanoparticles expose a supreme rate of heat transfer than the copper nanoparticles in a blood base fluid. Compared to hybrid and copper nanofluid, the blood base fluid has a lower temperature. (shrink)

Blood coagulation is regulated through a complex network of biochemical reactions of blood factors. The main acting enzyme is thrombin whose propagation in blood plasma leads to fibrin clot formation. Spontaneous clot formation is normally controlled through the action of different plasma inhibitors, in particular, through the thrombin binding by antithrombin. In the current study we develop a mathematical model of clot formation both in quiescent plasma and in blood flow and determine the analytical conditions (...) on the antithrombin concentration corresponding to different regimes of blood coagulation. (shrink)

Blood coagulation is regulated through a complex network of biochemical reactions of blood factors. The main acting enzyme is thrombin whose propagation in blood plasma leads to fibrin clot formation. Spontaneous clot formation is normally controlled through the action of different plasma inhibitors, in particular, through the thrombin binding by antithrombin. In the current study we develop a mathematical model of clot formation both in quiescent plasma and in blood flow and determine the analytical conditions (...) on the antithrombin concentration corresponding to different regimes of blood coagulation. (shrink)

Correct interpretation of the data from integral laboratory tests, including Thrombin Generation Test, requires biochemistry-based mathematical models of blood coagulation. The purpose of this study is to describe the experimental TGT data from healthy donors and hemophilia A and B patients. We derive a simplified ODE model and apply it to analyze the TGT data from healthy donors and HA/HB patients with in vitro added tissue factor pathway inhibitor antibody. This model allows the characterization of hemophilia patients in the (...) space of three most important model parameters. The proposed approach may provide a new quantitative tool for the analysis of experimental TGT. Also, it gives a reduced model of coagulation verified against clinical data to be used in future theoretical large-scale modeling of thrombosis in flow. (shrink)

_Pluriverse_, the final work of the American poet and philosopher Benjamin Paul Blood, was published posthumously in 1920. After an experience of the anaesthetic nitrous oxide during a dental operation, Blood came to the conclusion that his mind had been opened, that he had undergone a mystical experience, and that he had come to a realisation of the true nature of reality. This title is the fullest exposition of Blood’s esoteric Christian philosophy-cum-theology, which, though deemed wildly eccentric (...) by commentators both during his lifetime and later in the twentieth century, was nonetheless one of the most influential sources for American mystical-empiricism. In particular, Blood’s thought was a major inspiration for William James, and can be seen to prefigure the latter’s concept of Sciousness directly. (shrink)

_Pluriverse_, the final work of the American poet and philosopher Benjamin Paul Blood, was published posthumously in 1920. After an experience of the anaesthetic nitrous oxide during a dental operation, Blood came to the conclusion that his mind had been opened, that he had undergone a mystical experience, and that he had come to a realisation of the true nature of reality. This title is the fullest exposition of Blood’s esoteric Christian philosophy-cum-theology, which, though deemed wildly eccentric (...) by commentators both during his lifetime and later in the twentieth century, was nonetheless one of the most influential sources for American mystical-empiricism. In particular, Blood’s thought was a major inspiration for William James, and can be seen to prefigure the latter’s concept of Sciousness directly. (shrink)

INTRODUCTION WHEN, in As You Like it, Shakespeare makes Touchstone ask William, "Hast any philosophy in thee, Shepherd?" the thing that Touchstone means is ...