2,761 research outputs found
Neuroimaging evidence implicating cerebellum in support of sensory/cognitive processes associated with thirst.
Recent studies implicate the cerebellum, long considered strictly a motor control structure, in cognitive, sensory, and affective phenomenon. The cerebellum, a phylogenetically ancient structure, has reciprocal ancient connections to the hypothalamus, a structure important in vegetative functions. The present study investigated whether the cerebellum was involved in vegetative functions and the primal emotions engendered by them. Using positron emission tomography, we examined the effects on the cerebellum of the rise of plasma sodium concentration and the emergence of thirst in 10 healthy adults. The correlation of regional cerebral blood flow with subjects' ratings of thirst showed major activation in the vermal central lobule. During the development of thirst, the anterior and posterior quadrangular lobule, lingula, and the vermis were activated. At maximum thirst and then during irrigation of the mouth with water to alleviate dryness, the cerebellum was less activated. However, 3 min after drinking to satiation, the anterior quadrangular lobule and posterior cerebellum were highly activated. The increased cerebellar activity was not related to motor behavior as this did not occur. Instead, responses in ancient cerebellar regions (vermis, fastigal nucleus, archicerebellum) may be more directly related to vegetative and affective aspects of thirst experiences, whereas activity in neocerebellar (posterior) regions may be related to sensory and cognitive aspects. Moreover, the cerebellum is apparently not involved in the computation of thirst per se but rather is activated during changes in thirst/satiation state when the brain is "vigilant" and is monitoring its sensory systems. Some neocerebellar activity may also reflect an intentionality for gratification by drinking inherent in the consciousness of thirst
Charge Renormalization, Effective Interactions, and Thermodynamics of Deionized Colloidal Suspensions
Thermodynamic properties of charge-stabilised colloidal suspensions depend
sensitively on the effective charge of the macroions, which can be
substantially lower than the bare charge in the case of strong
counterion-macroion association. A theory of charge renormalization is
proposed, combining an effective one-component model of charged colloids with a
thermal criterion for distinguishing between free and associated counterions.
The theory predicts, with minimal computational effort, osmotic pressures of
deionized suspensions of highly charged colloids in close agreement with
large-scale simulations of the primitive model.Comment: 15 pages, 7 figure
The Unveiling of Lodgism vs. Christianity: Positively Discussed Only In The Light of Its Most Friendly and Authorized Source of Information by Representative Men of God
https://digitalcommons.acu.edu/crs_books/1061/thumbnail.jp
Decision Making about Risk of Infection by Young Adults with CF
Young people with cystic fibrosis (CF) are asked to avoid a number of environments associated with increased infection risk, but in practice they need to balance this with competing priorities such as building and sustaining relationships with friends and family. This study explored the process by which young people make these decisions. Mixed methods were used: a vignette study presenting choices around engaging in activities involving a degree of infection risk and a thematic analysis of participant's accounts of their decision making. The eight participants chose to engage in high risk behaviours in 59% of the choices. All participants chose to engage in at least one risky behavior, though this was less likely when the risk was significant. Thematic analysis revealed large areas of misunderstanding and lack of knowledge, leading to some potentially worrying misconceptions about the nature of infections and risk. Young people with CF are not currently making informed decisions around activities that involve increased risk of infection, and there is an urgent need for CF teams to address this in information provision
Weighted-density approximation for general nonuniform fluid mixtures
In order to construct a general density-functional theory for nonuniform
fluid mixtures, we propose an extension to multicomponent systems of the
weighted-density approximation (WDA) of Curtin and Ashcroft [Phys. Rev. A 32,
2909 (1985)]. This extension corrects a deficiency in a similar extension
proposed earlier by Denton and Ashcroft [Phys. Rev. A 42, 7312 (1990)], in that
that functional cannot be applied to the multi-component nonuniform fluid
systems with spatially varying composition, such as solid-fluid interfaces. As
a test of the accuracy of our new functional, we apply it to the calculation of
the freezing phase diagram of a binary hard-sphere fluid, and compare the
results to simulation and the Denton-Ashcroft extension.Comment: 4 pages, 4 figures, to appear in Phys. Rev. E as Brief Repor
Stability of Colloidal Quasicrystals
Freezing of charge-stabilized colloidal suspensions and relative stabilities
of crystals and quasicrystals are studied using thermodynamic perturbation
theory. Macroion interactions are modelled by effective pair potentials
combining electrostatic repulsion with polymer-depletion or van der Waals
attraction. Comparing free energies -- counterion terms included -- for
elementary crystals and rational approximants to icosahedral quasicrystals,
parameters are identified for which one-component quasicrystals are stabilized
by a compromise between packing entropy and cohesive energy.Comment: 6 pages, 4 figure
Recurrent episodes of Takotsubo cardiomyopathy in systemic sclerosis
Systemic sclerosis is an autoimmune disease characterized by fibrosis and small vessel vasculopathy, which affects various organ systems, such as the heart. Takotsubo cardiomyopathy is a transient cardiomyopathy in reaction to an emotional or physical trigger. There may be clinical and pathogenetic overlap between Takotsubo cardiomyopathy and primary systemic sclerosis heart disease, and some patients with systemic sclerosis have been diagnosed with recurrent Takotsubo cardiomyopathy. Our large systemic sclerosis clinical cohort was reviewed to identify cases diagnosed with Takotsubo cardiomyopathy. The clinical features, laboratory and imaging results were reviewed and evaluated to perform a comparison between cases. We identified five patients with systemic sclerosis, all female (age 68.6 ± 5.7 years), who were diagnosed with Takotsubo cardiomyopathy. Two of these patients had recurrent episodes: one case with a history of multiple episodes and the other with one recurrence. Typical features included repolarization abnormalities on the electrocardiogram and transient left ventricular dysfunction observed using echocardiography or cardiac magnetic resonance imaging. Our findings build upon previous reports and observations that systemic sclerosis may cause Takotsubo cardiomyopathy. To our knowledge, this is the largest case series of Takotsubo syndrome in patients with systemic sclerosis. This association may provide novel insights into the aetiopathogenesis of Takotsubo cardiomyopathy as part of primary systemic sclerosis heart involvement
Reconstruction of three-dimensional porous media using generative adversarial neural networks
To evaluate the variability of multi-phase flow properties of porous media at
the pore scale, it is necessary to acquire a number of representative samples
of the void-solid structure. While modern x-ray computer tomography has made it
possible to extract three-dimensional images of the pore space, assessment of
the variability in the inherent material properties is often experimentally not
feasible. We present a novel method to reconstruct the solid-void structure of
porous media by applying a generative neural network that allows an implicit
description of the probability distribution represented by three-dimensional
image datasets. We show, by using an adversarial learning approach for neural
networks, that this method of unsupervised learning is able to generate
representative samples of porous media that honor their statistics. We
successfully compare measures of pore morphology, such as the Euler
characteristic, two-point statistics and directional single-phase permeability
of synthetic realizations with the calculated properties of a bead pack, Berea
sandstone, and Ketton limestone. Results show that GANs can be used to
reconstruct high-resolution three-dimensional images of porous media at
different scales that are representative of the morphology of the images used
to train the neural network. The fully convolutional nature of the trained
neural network allows the generation of large samples while maintaining
computational efficiency. Compared to classical stochastic methods of image
reconstruction, the implicit representation of the learned data distribution
can be stored and reused to generate multiple realizations of the pore
structure very rapidly.Comment: 21 pages, 20 figure
Pharmacology of DB844, an orally active aza analogue of pafuramidine, in a monkey model of second stage human African trypanosomiasis
Novel drugs to treat human African trypanosomiasis (HAT) are still urgently needed despite the recent addition of nifurtimox-eflornithine combination therapy (NECT) to WHO Model Lists of Essential Medicines against second stage HAT, where parasites have invaded the central nervous system (CNS). The pharmacology of a potential orally available lead compound, N-methoxy-6-{5-[4-(N-methoxyamidino) phenyl]-furan-2-yl}-nicotinamidine (DB844), was evaluated in a vervet monkey model of second stage HAT, following promising results in mice. DB844 was administered orally to vervet monkeys, beginning 28 days post infection (DPI) with Trypanosoma brucei rhodesiense KETRI 2537. DB844 was absorbed and converted to the active metabolite 6-[5-(4-phenylamidinophenyl)-furanyl-2-yl]-nicotinamide (DB820), exhibiting plasma C(max) values of 430 and 190 nM for DB844 and DB820, respectively, after the 14th dose at 6 mg/kg qd. A 100-fold reduction in blood trypanosome counts was observed within 24 h of the third dose and, at the end of treatment evaluation performed four days post the last drug dose, trypanosomes were not detected in the blood or cerebrospinal fluid of any monkey. However, some animals relapsed during the 300 days of post treatment monitoring, resulting in a cure rate of 3/8 (37.5%) and 3/7 (42.9%) for the 5 mg/kg×10 days and the 6 mg/kg×14 days dose regimens respectively. These DB844 efficacy data were an improvement compared with pentamidine and pafuramidine both of which were previously shown to be non-curative in this model of CNS stage HAT. These data show that synthesis of novel diamidines with improved activity against CNS-stage HAT was possible
Crowding of Polymer Coils and Demixing in Nanoparticle-Polymer Mixtures
The Asakura-Oosawa-Vrij (AOV) model of colloid-polymer mixtures idealizes
nonadsorbing polymers as effective spheres that are fixed in size and
impenetrable to hard particles. Real polymer coils, however, are intrinsically
polydisperse in size (radius of gyration) and may be penetrated by smaller
particles. Crowding by nanoparticles can affect the size distribution of
polymer coils, thereby modifying effective depletion interactions and
thermodynamic stability. To analyse the influence of crowding on polymer
conformations and demixing phase behaviour, we adapt the AOV model to mixtures
of nanoparticles and ideal, penetrable polymer coils that can vary in size. We
perform Gibbs ensemble Monte Carlo simulations, including trial
nanoparticle-polymer overlaps and variations in radius of gyration. Results are
compared with predictions of free-volume theory. Simulation and theory
consistently predict that ideal polymers are compressed by nanoparticles and
that compressibility and penetrability stabilise nanoparticle-polymer mixtures.Comment: 18 pages, 4 figure
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