6,533 research outputs found
Improved RNA pseudoknots prediction and classification using a new topological invariant
We propose a new topological characterization of RNA secondary structures
with pseudoknots based on two topological invariants. Starting from the classic
arc-representation of RNA secondary structures, we consider a model that
couples both I) the topological genus of the graph and II) the number of
crossing arcs of the corresponding primitive graph. We add a term proportional
to these topological invariants to the standard free energy of the RNA
molecule, thus obtaining a novel free energy parametrization which takes into
account the abundance of topologies of RNA pseudoknots observed in RNA
databases.Comment: 9 pages, 6 figure
Passive exercise of the hind limbs after complete thoracic transection of the spinal cord promotes cortical reorganization.
Physical exercise promotes neural plasticity in the brain of healthy subjects and modulates pathophysiological neural plasticity after sensorimotor loss, but the mechanisms of this action are not fully understood. After spinal cord injury, cortical reorganization can be maximized by exercising the non-affected body or the residual functions of the affected body. However, exercise per se also produces systemic changes - such as increased cardiovascular fitness, improved circulation and neuroendocrine changes - that have a great impact on brain function and plasticity. It is therefore possible that passive exercise therapies typically applied below the level of the lesion in patients with spinal cord injury could put the brain in a more plastic state and promote cortical reorganization. To directly test this hypothesis, we applied passive hindlimb bike exercise after complete thoracic transection of the spinal cord in adult rats. Using western blot analysis, we found that the level of proteins associated with plasticity - specifically ADCY1 and BDNF - increased in the somatosensory cortex of transected animals that received passive bike exercise compared to transected animals that received sham exercise. Using electrophysiological techniques, we then verified that neurons in the deafferented hindlimb cortex increased their responsiveness to tactile stimuli delivered to the forelimb in transected animals that received passive bike exercise compared to transected animals that received sham exercise. Passive exercise below the level of the lesion, therefore, promotes cortical reorganization after spinal cord injury, uncovering a brain-body interaction that does not rely on intact sensorimotor pathways connecting the exercised body parts and the brain
Enumeration of RNA structures by Matrix Models
We enumerate the number of RNA contact structures according to their genus,
i.e. the topological character of their pseudoknots. By using a recently
proposed matrix model formulation for the RNA folding problem, we obtain exact
results for the simple case of an RNA molecule with an infinitely flexible
backbone, in which any arbitrary pair of bases is allowed. We analyze the
distribution of the genus of pseudoknots as a function of the total number of
nucleotides along the phosphate-sugar backbone.Comment: RevTeX, 4 pages, 2 figure
Unbiased estimates of galaxy scaling relations from photometric redshift surveys
Many physical properties of galaxies correlate with one another, and these
correlations are often used to constrain galaxy formation models. Such
correlations include the color-magnitude relation, the luminosity-size
relation, the Fundamental Plane, etc. However, the transformation from
observable (e.g. angular size, apparent brightness) to physical quantity
(physical size, luminosity), is often distance-dependent. Noise in the distance
estimate will lead to biased estimates of these correlations, thus compromising
the ability of photometric redshift surveys to constrain galaxy formation
models. We describe two methods which can remove this bias. One is a
generalization of the V_max method, and the other is a maximum likelihood
approach. We illustrate their effectiveness by studying the size-luminosity
relation in a mock catalog, although both methods can be applied to other
scaling relations as well. We show that if one simply uses photometric
redshifts one obtains a biased relation; our methods correct for this bias and
recover the true relation
Il censimento delle strade appartenenti alla rete extraurbana: aspetti metodologici e normativi
La mancata classificazione della rete comporta da un lato la quasi impossibile realizzazione dei Piani del Traffico della Viabilità Extraurbana (PTVE) e dall???altro determina la quasi impossibile definizione delle priorità in termini di manutenzione e ottimizzazione delle infrastrutture esistenti. A questi si aggiungono altri due aspetti: le Amministrazioni sono chiamate a perseguire l???innalzamento dei livelli di sicurezza stradale e dall???altro lato devono assicurare la totale accessibilità dei territori, il tutto in un contesto di totale contenimento della spesa
Vibrational properties of inclusion complexes: the case of indomethacin-cyclodextrin
Vibrational properties of inclusion complexes with cyclodextrins are studied
by means of Raman spectroscopy and numerical simulation. In particular, Raman
spectra of the non-steroidal, anti-inflammatory drug indomethacin undergo
notable changes in the energy range between 1600 and 1700 cm when
inclusion complexes with cyclodextrins are formed. By using both \emph{ab
initio} quantum chemical calculations and molecular dynamics, we studied how to
relate such changes to the geometry of the inclusion process, disentangling
single-molecule effects, from changes in the solid state structure or
dimerization processes.Comment: 14 file figure
Legacy and shockwaves: A spatial analysis of strengthening resilience of the power grid in Connecticut
Grid resilience and reliability are pivotal in the transition to low and zero carbon energy systems. Tree-trimming operations (TTOs) have become a pivotal tool for increasing the resilience power grids, especially in highly forested regions. Building on recent literature, we aim at assessing the temporal and spatial extents of the benefits that TTOs produce on the grid from three perspectives: the frequency, extent, and duration of outages. We use a unique dataset provided by Eversource Energy, New England's largest utility company, with outage events from 2009 to 2015. We employ spatial econometrics to investigate both the legacy and spatial extent of TTOs. Our results show TTOs benefits occur for all three metrics for at least 4 years, and benefits spillover to up to 2 km throughout the treated areas, with significant spatial spillovers across the state greater than direct effects. Implications lead to supporting TTOs as part of the hardening policies for utility companies, especially as home-based activities increase in importance in a post-COVID19 world
Hyperbolic Balance Laws with a Non Local Source
This paper is devoted to hyperbolic systems of balance laws with non local
source terms. The existence, uniqueness and Lipschitz dependence proved here
comprise previous results in the literature and can be applied to physical
models, such as Euler system for a radiating gas and Rosenau regularization of
the Chapman-Enskog expansion.Comment: 26 page
Market Power and Patent Strategies: Evidence from Renaissance Venice
This paper exploits the introduction of the first regularized patent system, which appeared in the Venetian Republic in 1474, to examine the factors shaping inventors\u2019 propensity to use a new form of intellectual property. We combine detailed information on craft guilds and patents in Renaissance Venice and show a negative association between patenting activity and guild statutory norms that strongly restricted entry and price competition. Our analysis shows that the heterogeneity in patenting activity documented by the industrial organization literature is not a special feature of modern technologies, but is rather a persistent phenomenon affected by market power
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