229 research outputs found
Construction of wedge-local nets of observables through Longo-Witten endomorphisms. II
In the first part, we have constructed several families of interacting
wedge-local nets of von Neumann algebras. In particular, there has been
discovered a family of models based on the endomorphisms of the U(1)-current
algebra of Longo-Witten.
In this second part, we further investigate endomorphisms and interacting
models. The key ingredient is the free massless fermionic net, which contains
the U(1)-current net as the fixed point subnet with respect to the U(1) gauge
action. Through the restriction to the subnet, we construct a new family of
Longo-Witten endomorphisms on the U(1)-current net and accordingly interacting
wedge-local nets in two-dimensional spacetime. The U(1)-current net admits the
structure of particle numbers and the S-matrices of the models constructed here
do mix the spaces with different particle numbers of the bosonic Fock space.Comment: 33 pages, 1 tikz figure. The final version is available under Open
Access. CC-B
On Multifractal Structure in Non-Representational Art
Multifractal analysis techniques are applied to patterns in several abstract
expressionist artworks, paintined by various artists. The analysis is carried
out on two distinct types of structures: the physical patterns formed by a
specific color (``blobs''), as well as patterns formed by the luminance
gradient between adjacent colors (``edges''). It is found that the analysis
method applied to ``blobs'' cannot distinguish between artists of the same
movement, yielding a multifractal spectrum of dimensions between about 1.5-1.8.
The method can distinguish between different types of images, however, as
demonstrated by studying a radically different type of art. The data suggests
that the ``edge'' method can distinguish between artists in the same movement,
and is proposed to represent a toy model of visual discrimination. A ``fractal
reconstruction'' analysis technique is also applied to the images, in order to
determine whether or not a specific signature can be extracted which might
serve as a type of fingerprint for the movement. However, these results are
vague and no direct conclusions may be drawn.Comment: 53 pp LaTeX, 10 figures (ps/eps
All-passive pixel super-resolution of time-stretch imaging
Based on image encoding in a serial-temporal format, optical time-stretch
imaging entails a stringent requirement of state-of-the- art fast data
acquisition unit in order to preserve high image resolution at an ultrahigh
frame rate --- hampering the widespread utilities of such technology. Here, we
propose a pixel super-resolution (pixel-SR) technique tailored for time-stretch
imaging that preserves pixel resolution at a relaxed sampling rate. It
harnesses the subpixel shifts between image frames inherently introduced by
asynchronous digital sampling of the continuous time-stretch imaging process.
Precise pixel registration is thus accomplished without any active
opto-mechanical subpixel-shift control or other additional hardware. Here, we
present the experimental pixel-SR image reconstruction pipeline that restores
high-resolution time-stretch images of microparticles and biological cells
(phytoplankton) at a relaxed sampling rate (approx. 2--5 GSa/s) --- more than
four times lower than the originally required readout rate (20 GSa/s) --- is
thus effective for high-throughput label-free, morphology-based cellular
classification down to single-cell precision. Upon integration with the
high-throughput image processing technology, this pixel-SR time- stretch
imaging technique represents a cost-effective and practical solution for large
scale cell-based phenotypic screening in biomedical diagnosis and machine
vision for quality control in manufacturing.Comment: 17 pages, 8 figure
Growing pains in children
We review the clinical manifestations of "growing pains", the most common form of episodic childhood musculoskeletal pain. Physicians should be careful to adhere to clear clinical criteria as described in this review before diagnosing a child with growing pain. We expand on current theories on possible causes of growing pains and describe the management of these pains and the generally good outcome in nearly all children
What drives sound symbolism? Different acoustic cues underlie sound-size and sound-shape mappings
Sound symbolism refers to the non-arbitrary mappings that exist between phonetic properties of speech sounds and their meaning. Despite there being an extensive literature on the topic, the acoustic features and psychological mechanisms that give rise to sound symbolism are not, as yet, altogether clear. The present study was designed to investigate whether different sets of acoustic cues predict size and shape symbolism, respectively. In two experiments, participants judged whether a given consonant-vowel speech sound was large or small, round or angular, using a size or shape scale. Visual size judgments were predicted by vowel formant F1 in combination with F2, and by vowel duration. Visual shape judgments were, however, predicted by formants F2 and F3. Size and shape symbolism were thus not induced by a common mechanism, but rather were distinctly affected by acoustic properties of speech sounds. These findings portray sound symbolism as a process that is not based merely on broad categorical contrasts, such as round/unround and front/back vowels. Rather, individuals seem to base their sound-symbolic judgments on specific sets of acoustic cues, extracted from speech sounds, which vary across judgment dimensions
Ischemia reperfusion dysfunction changes model-estimated kinetics of myofilament interaction due to inotropic drugs in isolated hearts
BACKGROUND: The phase-space relationship between simultaneously measured myoplasmic [Ca(2+)] and isovolumetric left ventricular pressure (LVP) in guinea pig intact hearts is altered by ischemic and inotropic interventions. Our objective was to mathematically model this phase-space relationship between [Ca(2+)] and LVP with a focus on the changes in cross-bridge kinetics and myofilament Ca(2+ )sensitivity responsible for alterations in Ca(2+)-contraction coupling due to inotropic drugs in the presence and absence of ischemia reperfusion (IR) injury. METHODS: We used a four state computational model to predict LVP using experimentally measured, averaged myoplasmic [Ca(2+)] transients from unpaced, isolated guinea pig hearts as the model input. Values of model parameters were estimated by minimizing the error between experimentally measured LVP and model-predicted LVP. RESULTS: We found that IR injury resulted in reduced myofilament Ca(2+ )sensitivity, and decreased cross-bridge association and dissociation rates. Dopamine (8 μM) reduced myofilament Ca(2+ )sensitivity before, but enhanced it after ischemia while improving cross-bridge kinetics before and after IR injury. Dobutamine (4 μM) reduced myofilament Ca(2+ )sensitivity while improving cross-bridge kinetics before and after ischemia. Digoxin (1 μM) increased myofilament Ca(2+ )sensitivity and cross-bridge kinetics after but not before ischemia. Levosimendan (1 μM) enhanced myofilament Ca(2+ )affinity and cross-bridge kinetics only after ischemia. CONCLUSION: Estimated model parameters reveal mechanistic changes in Ca(2+)-contraction coupling due to IR injury, specifically the inefficient utilization of Ca(2+ )for contractile function with diastolic contracture (increase in resting diastolic LVP). The model parameters also reveal drug-induced improvements in Ca(2+)-contraction coupling before and after IR injury
Bi-allelic variants in TSPOAP1, encoding the active zone protein RIMBP1, cause autosomal recessive dystonia
Dystonia is a debilitating hyperkinetic movement disorder, which can be transmitted as a monogenic trait. Here, we describe homozygous frameshift, nonsense and missense variants in TSPOAP1, encoding the active zone RIM-binding protein 1 (RIMBP1), as a novel genetic cause of autosomal recessive dystonia in seven subjects from three unrelated families. Subjects carrying loss-of-function variants presented with juvenile-onset progressive generalized dystonia, associated with intellectual disability and cerebellar atrophy. Conversely, subjects carrying a pathogenic missense variant (p.Gly1808Ser) presented with isolated adult-onset focal dystonia. In mice, complete loss of RIMBP1, known to reduce neurotransmission, led to motor abnormalities reminiscent of dystonia, decreased Purkinje cell dendritic arborization, and reduced numbers of cerebellar synapses. In vitro analysis of the p.Gly1808Ser variant showed larger spike-evoked calcium transients and enhanced neurotransmission, suggesting that RIMBP1-linked dystonia can be caused by either reduced or enhanced rates of spike-evoked release in relevant neural networks. Our findings establish a direct link between dysfunction of the presynaptic active zone and dystonia and highlight the critical role played by well-balanced neurotransmission in motor control and disease pathogenesis
A critical look at 50 years particle theory from the perspective of the crossing property
The crossing property is perhaps the most subtle aspect of the particle-field
relation. Although it is not difficult to state its content in terms of certain
analytic properties relating different matrixelements of the S-matrix or
formfactors, its relation to the localization- and positive energy spectral
principles requires a level of insight into the inner workings of QFT which
goes beyond anything which can be found in typical textbooks on QFT. This paper
presents a recent account based on new ideas derived from "modular
localization" including a mathematic appendix on this subject. Its main novel
achievement is the proof of the crossing property of formfactors from a
two-algebra generalization of the KMS condition. The main content of this
article is the presentation of the derailments of particle theory during more
than 4 decades: the S-matrix bootstrap, the dual model and its string theoretic
extension. Rather than being related to crossing, string theory is the (only
known) realization of a dynamic infinite component one-particle wave function
space and its associated infinite component field. Here "dynamic" means that,
unlike a mere collection of infinitely many irreducible unitary Poincar\'e
group representation or free fields, the formalism contains also operators
which communicate between the different irreducible Poincar\'e represenations
(the levels of the "infinite tower") and set the mass/spin spectrum. Wheras in
pre-string times there were unsuccessful attempts to achieve this in analogy to
the O(4,2) hydrogen spectrum by the use of higher noncompact groups, the
superstring in d=9+1, which uses instead (bosonic/fermionic) oscillators
obtained from multicomponent chiral currents is the only known unitary positive
energy solution of the dynamical infinite component pointlike localized field
project.Comment: 66 pages, addition of new results, addition of references, will
appear in this form in Foundations of Physic
Wastewater-based epidemiology in hazard forecasting and early-warning systems for global health risks
With the advent of the SARS-CoV-2 pandemic, Wastewater-Based Epidemiology (WBE) has been applied to track community infection in cities worldwide and has proven succesful as an early warning system for identification of hotspots and changingprevalence of infections (both symptomatic and asymptomatic) at a city or sub-city level. Wastewater is only one of environmental compartments that requires consideration. In this manuscript, we have critically evaluated the knowledge-base and preparedness for building early warning systems in a rapidly urbanising world, with particular attention to Africa, which experiences rapid population growth and urbanisation. We have proposed a Digital Urban Environment Fingerprinting Platform (DUEF) – a new approach in hazard forecasting and early-warning systems for global health risks and an extension to the existing concept of smart cities. The urban environment (especially wastewater) contains a complex mixture of substances including toxic chemicals, infectious biological agents and human excretion products. DUEF assumes that these specific endo- and exogenous residues, anonymously pooled by communities’ wastewater, are indicative of community-wide exposure and the resulting effects. DUEF postulates that the measurement of the substances continuously and anonymously pooled by the receiving environment (sewage, surface water, soils and air), can provide near real-time dynamic information about the quantity and type of physical, biological or chemical stressors to which the surveyed systems are exposed, and can create a risk profile on the potential effects of these exposures. Successful development and utilisation of a DUEF globally requires a tiered approach including: Stage I: network building, capacity building, stakeholder engagement as well as a conceptual model, followed by Stage II: DUEF development, Stage III: implementation, and Stage IV: management and utilization. We have identified four key pillars required for the establishment of a DUEF framework: (1) Environmental fingerprints, (2) Socioeconomic fingerprints, (3) Statistics and modelling and (4) Information systems. This manuscript critically evaluates the current knowledge base within each pillar and provides recommendations for further developments with an aim of laying grounds for successful development of global DUEF platforms
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