234 research outputs found
Absolute instruments and perfect imaging in geometrical optics
We investigate imaging by spherically symmetric absolute instruments that
provide perfect imaging in the sense of geometrical optics. We derive a number
of properties of such devices, present a general method for designing them and
use this method to propose several new absolute instruments, in particular a
lens providing a stigmatic image of an optically homogeneous region and having
a moderate refractive index range.Comment: 20 pages, 9 image
On God-Belief and Feeling Clean
Recent work has shown robust associations between morality and cleanliness. However, it is not known whether this association is equally consequential for everyone. I predicted that individuals high (vs. low) in God-belief would be more likely to draw upon feelings of cleanliness to represent their moral concerns. To test this hypothesis, I used a 2-week daily sampling protocol. In an initial session, I measured participants’ ( N = 135) level of God-belief. I then measured participants’ levels of daily cleanliness, neuroticism, impulsivity, and prosocial behaviors every evening. Daily feelings of cleanliness predicted lower levels of neuroticism but only for those high in God-belief. Daily impulsive behaviors predicted lower feelings of cleanliness, and daily prosocial behaviors predicted higher feelings of cleanliness. God-belief moderated these effects such that they were stronger for those higher, than lower, in God-belief. In closing, I discuss potential reasons for these moderation effects and other theoretical considerations. </jats:p
Symplectic connections and Fedosov's quantization on supermanifolds
A (biased and incomplete) review of the status of the theory of symplectic
connections on supermanifolds is presented. Also, some comments regarding
Fedosov's technique of quantization are made.Comment: Submitted to J. of Phys. Conf. Se
Cohomology of Filippov algebras and an analogue of Whitehead's lemma
We show that two cohomological properties of semisimple Lie algebras also
hold for Filippov (n-Lie) algebras, namely, that semisimple n-Lie algebras do
not admit non-trivial central extensions and that they are rigid i.e., cannot
be deformed in Gerstenhaber sense. This result is the analogue of Whitehead's
Lemma for Filippov algebras. A few comments about the n-Leibniz algebras case
are made at the end.Comment: plain latex, no figures, 29 page
ICP curve morphology and intracranial flow-volume changes: a simultaneous ICP and cine phase contrast MRI study in humans
Background: The intracranial pressure (ICP) curve with its different peaks has been extensively studied, but the exact physiological mechanisms behind its morphology are still not fully understood. Both intracranial volume change (ΔICV) and transmission of the arterial blood pressure have been proposed to shape the ICP curve. This study tested the hypothesis that the ICP curve correlates to intracranial volume changes. Methods: Cine phase contrast magnetic resonance imaging (MRI) examinations were performed in neuro-intensive care patients with simultaneous ICP monitoring. The MRI was set to examine cerebral arterial inflow and venous cerebral outflow as well as flow of cerebrospinal fluid over the foramen magnum. The difference in total flow into and out from the cranial cavity (Flowtot) over time provides the ΔICV. The ICP curve was compared to the Flowtot and the ΔICV. Correlations were calculated through linear and logarithmic regression. Student’s t test was used to test the null hypothesis between paired samples. Results: Excluding the initial ICP wave, P1, the mean R2 for the correlation between the ΔICV and the ICP was 0.75 for the exponential expression, which had a higher correlation than the linear (p = 0.005). The first ICP peaks correlated to the initial peaks of Flowtot with a mean R2 = 0.88. Conclusion: The first part, or the P1, of the ICP curve seems to be created by the first rapid net inflow seen in Flowtot while the rest of the ICP curve seem to correlate to the ΔICV
Mind Perception Is the Essence of Morality
Mind perception entails ascribing mental capacities to other entities, whereas moral judgment entails labeling entities as good or bad or actions as right or wrong. We suggest that mind perception is the essence of moral judgment. In particular, we suggest that moral judgment is rooted in a cognitive template of two perceived minds—a moral dyad of an intentional agent and a suffering moral patient. Diverse lines of research support dyadic morality. First, perceptions of mind are linked to moral judgments: dimensions of mind perception (agency and experience) map onto moral types (agents and patients), and deficits of mind perception correspond to difficulties with moral judgment. Second, not only are moral judgments sensitive to perceived agency and experience, but all moral transgressions are fundamentally understood as agency plus experienced suffering—that is, interpersonal harm—even ostensibly harmless acts such as purity violations. Third, dyadic morality uniquely accounts for the phenomena of dyadic completion (seeing agents in response to patients, and vice versa), and moral typecasting (characterizing others as either moral agents or moral patients). Discussion also explores how mind perception can unify morality across explanatory levels, how a dyadic template of morality may be developmentally acquired, and future directions
Effect of Dietary Zinc Oxide on Morphological Characteristics, Mucin Composition and Gene Expression in the Colon of Weaned Piglets
The trace element zinc is often used in the diet of weaned piglets, as high
doses have resulted in positive effects on intestinal health. However, the
majority of previous studies evaluated zinc supplementations for a short
period only and focused on the small intestine. The hypothesis of the present
study was that low, medium and high levels of dietary zinc (57, 164 and 2,425
mg Zn/kg from zinc oxide) would affect colonic morphology and innate host
defense mechanisms across 4 weeks post-weaning. Histological examinations were
conducted regarding the colonic morphology and neutral, acidic, sialylated and
sulphated mucins. The mRNA expression levels of mucin (MUC) 1, 2, 13, 20,
toll-like receptor (TLR) 2, 4, interleukin (IL)-1β, 8, 10, interferon-γ
(IFN-γ) and transforming growth factor-β (TGF-β) were also measured. The
colonic crypt area increased in an age-depending manner, and the greatest area
was found with medium concentration of dietary zinc. With the high
concentration of dietary zinc, the number of goblet cells containing mixed
neutral-acidic mucins and total mucins increased. Sialomucin containing goblet
cells increased age-dependently. The expression of MUC2 increased with age and
reached the highest level at 47 days of age. The expression levels of TLR2 and
4 decreased with age. The mRNA expression of TLR4 and the pro-inflammatory
cytokine IL-8 were down-regulated with high dietary zinc treatment, while
piglets fed with medium dietary zinc had the highest expression. It is
concluded that dietary zinc level had a clear impact on colonic morphology,
mucin profiles and immunological traits in piglets after weaning. Those
changes might support local defense mechanisms and affect colonic physiology
and contribute to the reported reduction of post-weaning diarrhea
Multiplicity of cerebrospinal fluid functions: New challenges in health and disease
This review integrates eight aspects of cerebrospinal fluid (CSF) circulatory dynamics: formation rate, pressure, flow, volume, turnover rate, composition, recycling and reabsorption. Novel ways to modulate CSF formation emanate from recent analyses of choroid plexus transcription factors (E2F5), ion transporters (NaHCO3 cotransport), transport enzymes (isoforms of carbonic anhydrase), aquaporin 1 regulation, and plasticity of receptors for fluid-regulating neuropeptides. A greater appreciation of CSF pressure (CSFP) is being generated by fresh insights on peptidergic regulatory servomechanisms, the role of dysfunctional ependyma and circumventricular organs in causing congenital hydrocephalus, and the clinical use of algorithms to delineate CSFP waveforms for diagnostic and prognostic utility. Increasing attention focuses on CSF flow: how it impacts cerebral metabolism and hemodynamics, neural stem cell progression in the subventricular zone, and catabolite/peptide clearance from the CNS. The pathophysiological significance of changes in CSF volume is assessed from the respective viewpoints of hemodynamics (choroid plexus blood flow and pulsatility), hydrodynamics (choroidal hypo- and hypersecretion) and neuroendocrine factors (i.e., coordinated regulation by atrial natriuretic peptide, arginine vasopressin and basic fibroblast growth factor). In aging, normal pressure hydrocephalus and Alzheimer's disease, the expanding CSF space reduces the CSF turnover rate, thus compromising the CSF sink action to clear harmful metabolites (e.g., amyloid) from the CNS. Dwindling CSF dynamics greatly harms the interstitial environment of neurons. Accordingly the altered CSF composition in neurodegenerative diseases and senescence, because of adverse effects on neural processes and cognition, needs more effective clinical management. CSF recycling between subarachnoid space, brain and ventricles promotes interstitial fluid (ISF) convection with both trophic and excretory benefits. Finally, CSF reabsorption via multiple pathways (olfactory and spinal arachnoidal bulk flow) is likely complemented by fluid clearance across capillary walls (aquaporin 4) and arachnoid villi when CSFP and fluid retention are markedly elevated. A model is presented that links CSF and ISF homeostasis to coordinated fluxes of water and solutes at both the blood-CSF and blood-brain transport interfaces
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