The frequency spectrum of finite samples from the intermittent silence process

It has been argued that the actual distribution of word frequencies could be reproduced or explained by generating a random sequence of letters and spaces according to the so-called intermittent silence process. The same kind of process could reproduce or explain the counts of other kinds of units from a wide range of disciplines. Taking the linguistic metaphor, we focus on the frequency spectrum, i.e., the number of words with a certain frequency, and the vocabulary size, i.e., the number of different words of text generated by an intermittent silence process. We derive and explain how to calculate accurately and efficiently the expected frequency spectrum and the expected vocabulary size as a function of the text size.Peer ReviewedPostprint (author's final draft

Optimization in complex networks

Many complex systems can be described in terms of networks of interacting units. Recent studies have shown that a wide class of both natural and artificial nets display a surprisingly widespread feature: the presence of highly heterogeneous distributions of links, providing an extraordinary source of robustness against perturbations. Although most theories concerning the origin of these topologies use growing graphs, here we show that a simple optimization process can also account for the observed regularities displayed by most complex nets. Using an evolutionary algorithm involving minimization of link density and average distance, four major types of networks are encountered: (a) sparse exponential-like networks, (b) sparse scale-free networks, (c) star networks and (d) highly dense networks, apparently defining three major phases. These constraints provide a new explanation for scaling of exponent about -3. The evolutionary consequences of these results are outlined.Peer ReviewedPostprint (author's final draft

Patterns in syntactic dependency networks

Many languages are spoken on Earth. Despite their diversity, many robust language universals are known to exist. All languages share syntax, i.e., the ability of combining words for forming sentences. The origin of such traits is an issue of open debate. By using recent developments from the statistical physics of complex networks, we show that different syntactic dependency networks (from Czech, German, and Romanian) share many nontrivial statistical patterns such as the small world phenomenon, scaling in the distribution of degrees, and disassortative mixing. Such previously unreported features of syntax organization are not a trivial consequence of the structure of sentences, but an emergent trait at the global scale.Peer ReviewedPostprint (published version

Selection, tinkering and emergence in complex networks: crossing the land of tinkering

Complex biological networks have very different origins than technologic ones. The latter involve extensive design and, as engineered structures, include a high level of optimization. The former involve (in principle) contingency and structural constraints, with new structures being incorporated through tinkering with previously evolved modules or units. However, the observation of the topological features of different biological nets suggests that nature can have a limited repertoire of ”attractors” that essentially optimize communication under some basic constraints of cost and architecture or that allow the biological nets to reach a high degree of homeostasis. Conversely, the topological features exhibited by some technology graphs indicate that tinkering and internal constraints play a key role, in spite of the ”designed” nature of these structures. Previous scenarios suggested to explain the overall trends of evolution are re-analyzed in light of topological patterns.Peer ReviewedPostprint (author's final draft

Current treatment of nosocomial pneumonia and ventilator-associated pneumonia

Nosocomial pneumonia; Treatment; Ventilator-associated pneumoniaPneumònia nosocomial; Tractament; Pneumònia associada al ventiladorNeumonía nosocomial; Tratamiento; Neumonía asociada al ventiladorHospital-acquired pneumonia and ventilator-associated pneumonia are severe nosocomial infections leading to high morbidity and mortality. Broad-spectrum antibiotics with coverage against all likely pathogens are recommended by the international guidelines. Inappropriate empirical treatment is one of the most important prognostic factors. Knowledge of local epidemiology and continuous microbiological surveillance is crucial for improving clinical approaches to empirical antimicrobial treatment. The development of protocols and policies for training healthcare professionals on preventive strategies, such as the "Pneumonia Zero" project, and improved implementation of antimicrobial stewardship practices, will aid early de-escalation of antibiotics and prevent resistance

Trinocular ystem for 3D motion and dense structure estimation

The relief of the seafloor is an important source of data for many scientists. In this paper we present an optical system to deal with underwater 3D reconstruction. This system is formed by three cameras that take images synchronously in a constant frame rate scheme. We use the images taken by these cameras to compute dense 3D reconstructions. We use Bundle Adjustment to estimate the motion of the trinocular rig. Given the path followed by the system, we get a dense map of the observed scene by registering the different dense local reconstructions in a unique and bigger one.Peer Reviewe

Predicting the Electronic Absorption Band Shape of Azobenzene Photoswitches

Simulations based on molecular dynamics coupled to excitation energy calculations were used to generate simulated absorption spectra for a family of halide derivatives of azobenzene, a family of photoswitch molecules with a weak absorption band around 400-600 nm and potential uses in living tissue. This is a case where using the conventional approach in theoretical spectroscopy (estimation of absorption maxima based on the vertical transition from the potential energy minimum on the ground electronic state) does not provide valid results that explain how the observed band shape extends towards the low energy region of the spectrum. The method affords a reasonable description of the main features of the low-energy UV-Vis spectra of these compounds. A bathochromic trend was detected linked to the size of the halide atom. Analysis of the excitation reveals a correlation between the energy of the molecular orbital where excitation starts and the energy of the highest occupied atomic orbital of the free halide atom. This was put to the test with a new brominated compound with good results. The energy level of the highest occupied orbital on the free halide was identified as a key factor that strongly affects the energy gap in the photoswitch. This opens the way for the design of bathochromically shifted variants of the photoswitch with possible applications

On the Computational Design of Azobenzene-Based Multi-State Photoswitches

In order to theoretically design multi-state photoswitches with specific properties, an exhaustive computational study is first carried out for an azobenzene dimer that has been recently synthesized and experimentally studied. This study allows for a full comprehension of the factors that govern the photoactivated isomerization processes of these molecules so to provide a conceptual/computational protocol that can be applied to generic multi-state photoswitches. From this knowledge a new dimer with a similar chemical design is designed and also fully characterized. Our theoretical calculations predict that the new dimer proposed is one step further in the quest for a double photoswitch, where the four metastable isomers could be selectively interconverted through the use of different irradiation sequences

Adjunctive Hemoadsorption Therapy with CytoSorb in Patients with Septic/Vasoplegic Shock: A Best Practice Consensus Statement

Hemoadsorption; Hyperinflammation; Septic shockHemoadsorción; Hiperinflamación; Shock sépticoHemoadsorció; Hiperinflamació; Shock sèpticA dysregulated host response is a common feature in critically ill patients due to both infectious and non-infectious origins that can lead to life-threatening organ dysfunction, which is still the primary cause of death in intensive care units worldwide. In its course, pathologic, unregulated levels of inflammatory mediators are often released into the circulation, a phenomenon also referred to as a “cytokine storm”. To date, there are no approved therapies to modulate the excessive immune response and limit hyperinflammation with the goal of preventing related organ failure and death. In this context, extracorporeal blood purification therapies aiming at the alteration of the host inflammatory response through broad-spectrum, non-selective removal of inflammatory mediators have come into focus. A novel hemoadsorption device (CytoSorb®, CytoSorbents Inc., Princeton, NJ, USA) has shown promising results in patients with hyperinflammation from various origins. Although a significant body of literature exists, there is ongoing research to address many important remaining questions, including the optimal selection of patient groups who might benefit the most, optimal timing for therapy initiation, optimal schedule for adsorber exchanges and therapy duration, as well as an investigation into the potential removal of concomitant antibiotics and other medications. In this review, we discuss the existing evidence and provide a consensus-based best practice guidance for CytoSorb® hemoadsorption therapy in patients with vasoplegic shock.This work was partially funded (artwork, editing) by CytoSorbents Inc. US Monmouth Junction, NJ, USA