436 research outputs found
Microbial Production of Short Chain Fatty Acids from Lignocellulosic Biomass:Current Processes and Market
Biological production of organic acids from conversion of biomass derivatives has received increased attention among scientists and engineers and in business because of the attractive properties such as renewability, sustainability, degradability, and versatility. The aim of the present review is to summarize recent research and development of short chain fatty acids production by anaerobic fermentation of nonfood biomass and to evaluate the status and outlook for a sustainable industrial production of such biochemicals. Volatile fatty acids (VFAs) such as acetic acid, propionic acid, and butyric acid have many industrial applications and are currently of global economic interest. The focus is mainly on the utilization of pretreated lignocellulosic plant biomass as substrate (the carbohydrate route) and development of the bacteria and processes that lead to a high and economically feasible production of VFA. The current and developing market for VFA is analyzed focusing on production, prices, and forecasts along with a presentation of the biotechnology companies operating in the market for sustainable biochemicals. Finally, perspectives on taking sustainable product of biochemicals from promise to market introduction are reviewed
Fundamental aspects of cardiovascular regulation in predisposition to atrial fibrillation
Background: Atrial fibrillation is the most common sustained arrhythmia in cardiology. The structural factors leading to atrial fibrillation are well known, but there should be also regarded the functional factors. In 2014, the Task Force published guidelines for atrial fibrillation describing the importance of the vegetative nervous system in creating predisposition to atrial fibrillation although it describes that the mechanism is not completely clear. Furthermore, it is important to understand this mechanism, regarding the increasing number of patients affected by atrial fibrillation without any structural heart diseases. The aim of this work is to understand the physiological background of the predisposition to the appearance and recurrence of atrial fibrillation regarding the role of neural regulatory systems of the heart, especially when no structural heart diseases are present. Therefore, the following is a fundamental analysis of the neural regulation of heart rhythm, including the vegetative nervous system at its medullar and central levels and also the cerebral cortex input in heart regulation. Conclusions: The predisposition to atrial fibrillation regarding the neural regulatory systems of the heart can be pinpointed to three key factors: 1. Central over-activity; 2. Sympathetic efferent overflow towards the heart in rest state; 3. Parasympathetic exhaustion and break-down of the parasymphatetic protective function
New approach to heart rate variability analysis based on cardiophysiological biomarkers
Background: The heart rate variability (HRV) analysis is a well-known method demonstrating its value over the years in different medical fields. However, it still has its known limitations. Material and methods: The new approach to HRV analysis is based on a complementary HRV standard analysis with new cardiophysiological biomarkers. The biomarkers are assessed on cardiorhythmograms obtained by a 5-minute ECG recording using a specialized hardware (Polyspectrum-HRV-device, Neurosoft). Results: A possible applicative value of the biomarkers is shown on examples of how a prognosis for recurrence of atrial fibrillation (AFib) could be made. When in a rest-state cardiorhythmogram are observed LF drops and are followed by a pathological counterregulation, prognostically, recurrence of atrial fibrillation is expected. When in a cardiorhythmogram LF drops are observed and are followed by a physiological counterregulation, prognostically, sinus rhythm is expected. Physiological background of the biomarkers: increased central modulation of the heart in rest state of a patient, a sympathetic overflow of the heart in calm state and insufficiency of compensatory parasymphatetic counteractivation. Limitations of the paper: this is a methodological paper without description of patients. This paper will be followed by a clinical paper in which we are going to describe the validation of these cardiophysiological biomarkers on patients with AFib. Conclusions: Complementary to the standard HRV analysis, cardiophysiological biomarkers should be assessed: LF drops and HF counterregulation could be used for prognosis construction in cardiology
Closed-loop auditory stimulation method to modulate sleep slow waves and motor learning performance in rats
Slow waves and cognitive output have been modulated in humans by phase-targeted auditory stimulation. However, to advance its technical development and further our understanding, implementation of the method in animal models is indispensable. Here, we report the successful employment of slow waves’ phase-targeted closed-loop auditory stimulation (CLAS) in rats. To validate this new tool both conceptually and functionally, we tested the effects of up- and down-phase CLAS on proportions and spectral characteristics of sleep, and on learning performance in the single-pellet reaching task, respectively. Without affecting 24 hr sleep-wake behavior, CLAS specifically altered delta (slow waves) and sigma (sleep spindles) power persistently over chronic periods of stimulation. While up-phase CLAS does not elicit a significant change in behavioral performance, down-phase CLAS exerted a detrimental effect on overall engagement and success rate in the behavioral test. Overall CLAS-dependent spectral changes were positively correlated with learning performance. Altogether, our results provide proof-of-principle evidence that phase-targeted CLAS of slow waves in rodents is efficient, safe, and stable over chronic experimental periods, enabling the use of this high-specificity tool for basic and preclinical translational sleep research.Fil: Moreira, Carlos G. Universitat Zurich; SuizaFil: Baumann, Christian R.. Universitat Zurich; Suiza. Neuroscience Center Zurich; SuizaFil: Scandella, Maurizio. Universitat Zurich; SuizaFil: Nemirovsky, Sergio Ivan. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales; ArgentinaFil: Leach, Sven. University Children's Hospital Zurich; SuizaFil: Huber, Reto. University Children's Hospital Zurich; Suiza. Universitat Zurich; SuizaFil: Noain, Daniela Maria Clara. University Hospital Zurich; Suiza. Universitat Zurich; Suiz
Unitary Positive-Energy Representations of Scalar Bilocal Quantum Fields
The superselection sectors of two classes of scalar bilocal quantum fields in
D>=4 dimensions are explicitly determined by working out the constraints
imposed by unitarity. The resulting classification in terms of the dual of the
respective gauge groups U(N) and O(N) confirms the expectations based on
general results obtained in the framework of local nets in algebraic quantum
field theory, but the approach using standard Lie algebra methods rather than
abstract duality theory is complementary. The result indicates that one does
not lose interesting models if one postulates the absence of scalar fields of
dimension D-2 in models with global conformal invariance. Another remarkable
outcome is the observation that, with an appropriate choice of the Hamiltonian,
a Lie algebra embedded into the associative algebra of observables completely
fixes the representation theory.Comment: 27 pages, v3: result improved by eliminating redundant assumptio
Supervised Learning in SNN via Reward-Modulated Spike-Timing-Dependent Plasticity for a Target Reaching Vehicle
Spiking neural networks (SNNs) offer many advantages over traditional artificial neural networks (ANNs) such as biological plausibility, fast information processing, and energy efficiency. Although SNNs have been used to solve a variety of control tasks using the Spike-Timing-Dependent Plasticity (STDP) learning rule, existing solutions usually involve hard-coded network architectures solving specific tasks rather than solving different kinds of tasks generally. This results in neglecting one of the biggest advantages of ANNs, i.e., being general-purpose and easy-to-use due to their simple network architecture, which usually consists of an input layer, one or multiple hidden layers and an output layer. This paper addresses the problem by introducing an end-to-end learning approach of spiking neural networks constructed with one hidden layer and reward-modulated Spike-Timing-Dependent Plasticity (R-STDP) synapses in an all-to-all fashion. We use the supervised reward-modulated Spike-Timing-Dependent-Plasticity learning rule to train two different SNN-based sub-controllers to replicate a desired obstacle avoiding and goal approaching behavior, provided by pre-generated datasets. Together they make up a target-reaching controller, which is used to control a simulated mobile robot to reach a target area while avoiding obstacles in its path. We demonstrate the performance and effectiveness of our trained SNNs to achieve target reaching tasks in different unknown scenarios
Large non-Gaussian Halo Bias from Single Field Inflation
We calculate Large Scale Structure observables for non-Gaussianity arising
from non-Bunch-Davies initial states in single field inflation. These scenarios
can have substantial primordial non-Gaussianity from squeezed (but observable)
momentum configurations. They generate a term in the halo bias that may be more
strongly scale-dependent than the contribution from the local ansatz. We also
discuss theoretical considerations required to generate an observable
signature.Comment: 30 pages, 14 figures, typos corrected and minor changes to match
published version JCAP09(2012)00
The Evolution of Fangs, Venom, and Mimicry Systems in Blenny Fishes
Venom systems have evolved on multiple occasions
across the animal kingdom, and they can act as key
adaptations to protect animals from predators.
Consequently, venomous animals serve as models
for a rich source of mimicry types, as non-venomous
species benefit from reductions in predation risk by
mimicking the coloration, body shape, and/or movement
of toxic counterparts. The frequent evolution
of such deceitful imitations provides notable
examples of phenotypic convergence and are often
invoked as classic exemplars of evolution by natural
selection. Here, we investigate the evolution of fangs,
venom, and mimetic relationships in reef fishes from
the tribe Nemophini (fangblennies). Comparative
morphological analyses reveal that enlarged canine
teeth (fangs) originated at the base of the Nemophini
radiation and have enabled a micropredatory feeding
strategy in non-venomous Plagiotremus spp. Subsequently,
the evolution of deep anterior grooves and
their coupling to venom secretory tissue provide
Meiacanthus spp. with toxic venom that they effectively
employ for defense. We find that fangblenny
venom contains a number of toxic components that
have been independently recruited into other animal
venoms, some of which cause toxicity via interactions
with opioid receptors, and result in a multifunctional
biochemical phenotype that exerts potent hypotensive
effects. The evolution of fangblenny venom has
seemingly led to phenotypic convergence via the formation
of a diverse array of mimetic relationships that
provide protective (Batesian mimicry) and predatory
(aggressive mimicry) benefits to other fishes.
Our results further our understanding of how novel
morphological and biochemical adaptations stimulate
ecological interactions in the natural world
Anisotropic flow of charged hadrons, pions and (anti-)protons measured at high transverse momentum in Pb-Pb collisions at TeV
The elliptic, , triangular, , and quadrangular, , azimuthal
anisotropic flow coefficients are measured for unidentified charged particles,
pions and (anti-)protons in Pb-Pb collisions at TeV
with the ALICE detector at the Large Hadron Collider. Results obtained with the
event plane and four-particle cumulant methods are reported for the
pseudo-rapidity range at different collision centralities and as a
function of transverse momentum, , out to GeV/.
The observed non-zero elliptic and triangular flow depends only weakly on
transverse momentum for GeV/. The small dependence
of the difference between elliptic flow results obtained from the event plane
and four-particle cumulant methods suggests a common origin of flow
fluctuations up to GeV/. The magnitude of the (anti-)proton
elliptic and triangular flow is larger than that of pions out to at least
GeV/ indicating that the particle type dependence persists out
to high .Comment: 16 pages, 5 captioned figures, authors from page 11, published
version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/186
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