Glassy phases of the Gaussian core model.

We present results from molecular dynamics simulations exploring the supercooled dynamics of the Gaussian Core Model in the low- and intermediate-density regimes. In particular, we analyse the transition from the low-density hard-sphere-like glassy dynamics to the high-density one. The dynamics at low densities is well described by the caging mechanism, giving rise to intermittent dynamics. At high densities, the particles undergo a more continuous motion in which the concept of cage loses its meaning. We elaborate on the idea that these different supercooled dynamics are in fact the precursors of two different glass states.

The Comorbidities, Radiographic Findings, Age, and Lymphopenia (CORAL) Tool: A Diagnostic Ally for Emergency Physicians Created for the COVID-19 Crisis and Beyond.

BACKGROUND: This study aimed to develop a novel clinical approach to predict intensive care unit (ICU) admission and mortality among coronavirus disease 2019 (COVID-19) patients in the emergency department (ED). METHODS: A retrospective cohort study was conducted including adults ≥ 18 years diagnosed with COVID-19 in the emergency department and admitted to the ICU between March and July 2020 in an academic hospital. The outcome variables were mortality and ICU admission. Additional variables that were collected included sex, age, comorbidities, symptom phenotype, and laboratory (lymphopenia) and imaging findings. A logistic regression model was used to construct and validate the risk models. RESULTS: A total of 808 patients were included in the study; 61.9% were men. The mean age was 57.8 ± 15.9 years, and high blood pressure (HBP) was the most prevalent comorbidity (31.8%). Seventy-six (9.4%) patients were admitted to the ICU. Age ≥ 60 years, chronic obstructive pulmonary disease (COPD), lymphopenia, and imaging findings correlated with mortality. Age ≥ 60 years, lymphopenia (<1,000 cells per microliter), and hypothyroidism correlated with ICU admission. These variables were incorporated into a scoring system (Comorbidities, Radiographic findings, Age, and Lymphopenia (CORAL) tool) to predict mortality and ICU admission. CONCLUSIONS: Our Comorbidities, Radiographic findings, Age, and Lymphopenia (CORAL) tool is a practical tool for different clinical settings independent of access to advanced medical resources or technologies. CORAL is suitable for emergency physicians in low- and middle-income countries.

Analysis of the costs incurred by patients with Chagas disease: The experience in endemic municipalities in Colombia.

BACKGROUND: Out-of-pocket expenditure (OOP) are key costs (medical and non-medical) that many individuals incur to receive health services. They have been identified as a key access barrier for vulnerable populations, in particular for populations affected by neglected diseases with a chronic progression, such as Chagas disease. It is important to understand the costs of accessing healthcare services that are borne by patients with T. cruzi infection. METHODOLOGY: We prepared a structured survey for patients with T. cruzi infection/Chagas disease who were all treated by the healthcare system in endemic municipalities in Colombia. The results were analyzed according to three categories: 1. The socioeconomic profiling of the patients; 2. The costs of accommodation, food and transportation, in addition to the time spent commuting; and 3. the income losses (money that was not earned due to absence from work) related to treatment at the local primary care hospital or at the high-complexity reference hospital. MAIN FINDINGS: Ninety-one patients answered the survey voluntarily. The data revealed that, when treated at the specialized reference hospital, patients spent 5.5 times more on food and accommodation, transportation costs were five times higher, and the loss of earnings was three times higher than when they were treated at the local primary care hospital. Moreover, the amount of time spent on transportation was 4 times higher at the reference hospital. CONCLUSIONS: Providing comprehensive healthcare services for Chagas management at local primary healthcare hospitals would allow the most vulnerable patients to save on expenses related to medical and non-medical costs, in turn leading to higher adhesion to treatment thus benefiting the health system as a whole. These findings are in alignment with the WHO's World Health Assembly 2010 Resolution on the importance of treating Chagas at local primary care hospitals, thereby saving patients time and money, allowing for timely care, and promoting access to healthcare.

One-particle engine with a porous piston.

We propose a variation of the classical Szilard engine that uses a porous piston. Such an engine requires neither information about the position of the particle, nor the removal and subsequent insertion of the piston when resetting the engine to continue doing work by lifting a mass against a gravitational field. Though the engine operates in contact with a single thermal reservoir, the reset mechanism acts as a second reservoir, dissipating energy when a mass that has been lifted by the engine is removed to initiate a new operation cycle.

Colloidal model of two-step protocol for epitaxial growth in one dimension.

We explore the application of a two-step growth protocol to a one-dimensional colloidal model. The evolution of the system is described in terms of the time-dependence of both monomer and island densities,N1andN, while its structure is characterized by using distributions of the gap length, the capture zone, the inter-island distance, and the island length. Analytical results obtained from rate equations are compared with these from molecular dynamics simulations. Since the two-step growth protocol deals with nucleation and aggregation processes in two completely separated time regimes, it makes possible to gain better understanding and control on the island formation mechanism than the standard one-step protocol. The predicted features and advantages of the two-step process could be experimentally tested using deposition of colloidal spheres on pattern substrates.

On-site experience of a project to increase access to diagnosis and treatment of Chagas disease in high-risk endemic areas of Colombia.

Colombia has one of the largest burdens of Chagas disease globally, with about 438,000 people affected according to 2015 estimates. Despite this, < 1% of the population has had access to diagnosis and treatment. A patient-centered roadmap for Chagas disease was developed from 2015 onwards to address access barriers and increase diagnostic and therapeutic coverage and was implemented in five municipalities where Chagas disease is endemic. The mean number of people tested per year increased from 37 before the project to 262 following implementation, and the average days between medical order and diagnostic confirmation results decreased from 258 to 19. The mean days from diagnostic confirmation to treatment initiation decreased from 354 before the project to 135 after implementation. The 5,654 people tested included 3,467 women of childbearing age. The prevalence of T. cruzi infection was 11.5%, and thus far 266 people have received antitrypanosomal treatment. Collaborative creation and implementation of a patient-centered roadmap can address access barriers in specific contexts, helping to reduce the invisibility and burden of this neglected disease.

Discovering generative models from event logs: data-driven simulation vs deep learning.

A generative model is a statistical model capable of generating new data instances from previously observed ones. In the context of business processes, a generative model creates new execution traces from a set of historical traces, also known as an event log. Two types of generative business process models have been developed in previous work: data-driven simulation models and deep learning models. Until now, these two approaches have evolved independently, and their relative performance has not been studied. This paper fills this gap by empirically comparing a data-driven simulation approach with multiple deep learning approaches for building generative business process models. The study sheds light on the relative strengths of these two approaches and raises the prospect of developing hybrid approaches that combine these strengths.

Effect of softness on glass melting and re-entrant solidification in mixtures of soft and hard colloids.

We present a systematic investigation of the structure and dynamic properties of model soft-hard colloidal mixtures. Results of a coarse-grained theoretical model are contrasted with rheological data, where the soft and hard colloids are mimicked by large star polymers with high functionality as the soft component and smaller stars with ultrahigh functionality as the hard one. Previous work by us revealed the recovery of the ergodicity of glassy soft star solutions and subsequent arrested phase separation and re-entrant solid transition upon progressive addition of small hard depletants. Here, we use different components to show that a small variation in softness has a significant impact on the state diagram of such mixtures. In particular, we establish that rendering the soft component more penetrable and modifying the size ratio bring about a remarkable shift in both the phase separation region and the glass-melting line so that the region of restored ergodicity can be notably enhanced and extended to much higher star polymer concentrations than for pure systems. We further rationalize our findings by analyzing the features of the depletion interaction induced by the smaller component that result from the interplay between the size ratio and the softness of the large component. These results demonstrate the great sensitivity of the phase behavior of entropic mixtures to small changes in the molecular architecture of the soft stars and point to the importance of accounting for details of the internal microstructure of soft colloidal particles for tailoring the flow properties of soft composites.

Dynamical Properties of Concentrated Suspensions of Block Copolymer Stars in Shear Flow.

Block copolymer stars (BCSs) have been demonstrated to constitute versatile, self-assembling building blocks with tunable softness, functionalization, and shape. We investigate the dynamical properties of suspensions of short-arm BCSs under linear shear flow by means of extensive particle-based multiscale simulations. We determine the properties of the system for representative values of monomer packing fraction ranging from semidilute to concentrate regimes. We systematically analyze the formed network structures as a function of both shear rate and packing fraction, the reorganization of solvophobic patches, and the corresponding radial correlation functions. Connecting our findings with rheology, we calculate the viscosity as a function of shear rate and discuss the implications of the found shear thinning behavior.

Multi-particle collision dynamics for a coarse-grained model of soft colloids.

The growing interest in the dynamical properties of colloidal suspensions, both in equilibrium and under an external drive such as shear or pressure flow, requires the development of accurate methods to correctly include hydrodynamic effects due to the suspension in a solvent. In the present work, we generalize Multiparticle Collision Dynamics (MPCD) to be able to deal with soft, polymeric colloids. Our methods build on the knowledge of the monomer density profile that can be obtained from monomer-resolved simulations without hydrodynamics or from theoretical arguments. We hereby propose two different approaches. The first one simply extends the MPCD method by including in the simulations effective monomers with a given density profile, thus neglecting monomer-monomer interactions. The second one considers the macromolecule as a single penetrable soft colloid (PSC), which is permeated by an inhomogeneous distribution of solvent particles. By defining an appropriate set of rules to control the collision events between the solvent and the soft colloid, both linear and angular momenta are exchanged. We apply these methods to the case of linear chains and star polymers for varying monomer lengths and arm number, respectively, and compare the results for the dynamical properties with those obtained within monomer-resolved simulations. We find that the effective monomer method works well for linear chains, while the PSC method provides very good results for stars. These methods pave the way to extend MPCD treatments to complex macromolecular objects such as microgels or dendrimers and to work with soft colloids at finite concentrations.

Island size distribution with hindered aggregation.

We study the effect of hindered aggregation on the island formation processes for a one-dimensional model of epitaxial growth with arbitrary nucleus size i. In the proposed model, the attachment of monomers to islands is hindered by an aggregation barrier, ε_{a}, which decreases the hopping rate of monomers to the islands. As ε_{a} increases, the system exhibits a crossover between two different regimes; namely, from diffusion-limited aggregation to attachment-limited aggregation. The island size distribution, P(s), is calculated for different values of ε_{a} by a self-consistent approach involving the nucleation and aggregation capture kernels. The results given by the analytical model are compared with those from kinetic Monte Carlo simulations, finding a close agreement between both sets of data for all considered values of i and ε_{a}. As the aggregation barrier increases, the spatial effect of fluctuations on the density of monomers can be neglected and P(s) smoothly approximates to the limit distribution P(s)=δ_{s,i+1}. In the crossover regime the system features a complex and rich behavior, which can be explained in terms of the characteristic timescales of different microscopic processes.

Star Block-Copolymers in Shear Flow.

Star block-copolymers (SBCs) have been demonstrated to constitute self-assembling building blocks with specific softness, functionalization, shape, and flexibility. In this work, we study the behavior of an isolated SBC under a shear flow by means of particle-based multiscale simulations. We systematically analyze the conformational properties of low-functionality stars, as well as the formation of attractive patches on their corona as a function of the shear rate. We cover a wide range of system parameters, including functionality, amphiphilicity, and solvent quality. It is shown that SBCs display a richer structural and dynamical behavior than athermal star polymers in a shear flow [ Ripoll Phys. Rev. Lett. , 2006 , 96 , 188302 ], and, therefore, they are also interesting candidates to tune the viscoelastic properties of complex fluids. We identify three factors of patch reorganization under shear that lead to patch numbers and orientations depending on the shear rate, namely, free arms joining existing patches, fusion of medium-sized patches into bigger ones, and fission of large patches into two smaller ones under high shear rates. Because the conformation of single SBC is expected to be preserved in low-density bulk phases, the presented results are a first step in understanding and predicting the rheological properties of semidilute suspensions of this kind of polymers.

Rotation Dynamics of Star Block Copolymers under Shear Flow.

Star block-copolymers (SBCs) are macromolecules formed by a number of diblock copolymers anchored to a common central core, being the internal monomers solvophilic and the end monomers solvophobic. Recent studies have demonstrated that SBCs constitute self-assembling building blocks with specific softness, functionalization, shape and flexibility. Depending on different physical and chemical parameters, the SBCs can behave as flexible patchy particles. In this paper, we study the rotational dynamics of isolated SBCs using a hybrid mesoscale simulation technique. We compare three different approaches to analyze the dynamics: the laboratory frame, the non-inertial Eckart's frame and a geometrical approximation relating the conformation of the SBC to the velocity profile of the solvent. We find that the geometrical approach is adequate when dealing with very soft systems, while in the opposite extreme, the dynamics is best explained using the laboratory frame. On the other hand, the Eckart frame is found to be very general and to reproduced well both extreme cases. We also compare the rotational frequency and the kinetic energy with the definitions of the angular momentum and inertia tensor from recent publications.

First Colombian consensus on congenital Chagas and clinical approach for women of child-bearing age diagnosed with Chagas / Primer consenso colombiano sobre Chagas congénito y orientación clínica a mujeres en edad fértil con diagnóstico de Chagas

Congenital transmission of Chagas disease has not been extensively studied in Colombia, and there are no standardized processes in the health system regarding the specific diagnosis, treatment and follow-up of this disease. To generate recommendations on congenital Chagas disease and Chagas in women of childbearing age in Colombia, a consensus of experts was developed. An extensive literature search through the Medline database was carried out using the MeSH terms: «Chagas disease/congenital¼, «prevention and control¼, «diagnosis¼, «therapeutics¼ and «pregnancy¼. Appropriate abstracts were selected and the full texts were analyzed. The relevant information was synthesized, classified, and organized into tables and figures and was presented to a panel of experts, which was composed of 30 professionals from various fields. Based on the Delphi methodology, three rounds of consultation were conducted. The first and second rounds were based on electronic questionnaires that measured the level of consensus of each question among the participants. The third round was based on a face-to-face discussion focusing on those questions without consensus in the previous consultations. The evidence was adapted to national circumstances on a case-by-case basis, and the content the final document was approved. These recommendations are proposed for use in routine medical practice by health professionals in Colombia.

La transmisión congénita de la enfermedad de Chagas ha sido poco estudiada en Colombia y existen pocos procedimientos rutinarios en el sistema de salud para el manejo de esta enfermedad. Por ello se desarrolló un consenso de expertos dirigido a generar recomendaciones de diagnóstico y tratamiento de Chagas con- génito y orientación a mujeres en edad fértil. Con ese propósito se realizó una búsqueda extensiva de la literatura, empleando una combinación de términos Mes (Chagas, Chagas congénito, prevención, control, diagnóstico, tratamiento y embarazo) para reflejar el estado del arte en cada tema de interés. Después de ello, se leyeron los resúmenes y aquellos seleccionados para análisis del texto completo. La literatura relevante se sintetizo, clasifico y organizo en tablas y se presentó al panel de expertos, el cual estaba constituido por 30 profesionales en diferentes áreas. Mediante la metodología Delphi se realizaron 2 rondas de cuestionarios virtuales y una reunión presencial en los cuales se evaluaron los niveles de acuerdo entre los participantes. Los puntos con falta de consenso durante las 2 rondas virtuales se expusieron durante las mesas de discusión en la ronda presencial. La evidencia utilizada se adaptó a las particularidades nacionales según el caso y se aprobó el contenido del documento final. Se propone que estas recomendaciones sean usadas por profesionales de la salud en Colombia.

Validity of the Stokes-Einstein Relation in Soft Colloids up to the Glass Transition.

We investigate the dynamics of kinetically frozen block copolymer micelles of different softness across a wide range of particle concentrations, from the fluid to the onset of glassy behavior, through a combination of rheology, dynamic light scattering, and pulsed field gradient NMR spectroscopy. We additionally perform Brownian dynamics simulations based on an ultrasoft coarse-grained potential, which are found to be in quantitative agreement with experiments, capturing even the very details of dynamic structure factors S(Q,t) on approaching the glass transition. We provide evidence that for these systems the Stokes-Einstein relation holds up to the glass transition; given that it is violated for dense suspensions of hard colloids, our findings suggest that its validity is an intriguing signature of ultrasoft interactions.

Depletion, melting and reentrant solidification in mixtures of soft and hard colloids.

We present extensive experimental and theoretical investigations on the structure, phase behavior, dynamics and rheology of model soft-hard colloidal mixtures realized with large, multiarm star polymers as the soft component and smaller, compact stars as the hard one. The number and length of the arms in star polymers control their softness, whereas the size ratio, the overall density and the composition are additional parameters varied for the mixtures. A coarse-grained theoretical strategy is employed to predict the structure of the systems as well as their ergodicity properties on the basis of mode coupling theory, for comparison with rheological measurements on the samples. We discovered that dynamically arrested star-polymer solutions recover their ergodicity upon addition of colloidal additives. At the same time the system displays demixing instability, and the binodal of the latter meets the glass line in a way that leads, upon addition of a sufficient amount of colloidal particles, to an arrested phase separation and reentrant solidification. We present evidence for a subsequent solid-to-solid transition well within the region of arrested phase separation, attributed to a hard-sphere-mixture type of glass, due to osmotic shrinkage of the stars at high colloidal particle concentrations. We systematically investigated the interplay of star functionality and size ratio with glass melting and demixing, and rationalized our findings by the depletion of the big stars due to the smaller colloids. This new depletion potential in which, contrary to the classic colloid-polymer case, the hard component depletes the soft one, has unique and novel characteristics and allows the calculation of phase diagrams for such mixtures. This work covers a broad range of soft-hard colloidal mixture compositions in which the soft component exceeds the hard one in size and provides general guidelines for controlling the properties of such complex mixtures.

Dynamic phase diagram of soft nanocolloids.

We present a comprehensive experimental and theoretical study covering micro-, meso- and macroscopic length and time scales, which enables us to establish a generalized view in terms of structure-property relationship and equilibrium dynamics of soft colloids. We introduce a new, tunable block copolymer model system, which allows us to vary the aggregation number, and consequently its softness, by changing the solvophobic-to-solvophilic block ratio (m : n) over two orders of magnitude. Based on a simple and general coarse-grained model of the colloidal interaction potential, we verify the significance of interaction length σint governing both structural and dynamic properties. We put forward a quantitative comparison between theory and experiment without adjustable parameters, covering a broad range of experimental polymer volume fractions (0.001 ≤ϕ≤ 0.5) and regimes from ultra-soft star-like to hard sphere-like particles, that finally results in the dynamic phase diagram of soft colloids. In particular, we find throughout the concentration domain a strong correlation between mesoscopic diffusion and macroscopic viscosity, irrespective of softness, manifested in data collapse on master curves using the interaction length σint as the only relevant parameter. A clear reentrance in the glass transition at high aggregation numbers is found, recovering the predicted hard-sphere (HS) value in the hard-sphere like limit. Finally, the excellent agreement between our new experimental systems with different but already established model systems shows the relevance of block copolymer micelles as a versatile realization of soft colloids and the general validity of a coarse-grained approach for the description of the structure and dynamics of soft colloids.

Primer consenso colombiano sobre Chagas congénito y orientación clínica a mujeres en edad fértil con diagnóstico de Chagas / First Colombian consensus on congenital Chagas and clinical approach to women of fertile age diagnosed with Chagas

La transmisión congénita de la enfermedad de Chagas ha sido poco estudiada en Colombia y existen pocos procedimientos rutinarios en el sistema de salud para el manejo de esta enfermedad. Por ello se desarrolló un consenso de expertos dirigido a generar recomendaciones de diagnóstico y tratamiento de Chagas congénito y orientación a mujeres en edad fértil. Con ese propósito se realizó una búsqueda extensiva de la literatura, empleando una combinación de términos MeSH (Chagas, Chagas congénito, prevención, control, diagnóstico, tratamiento y embarazo) para reflejar el estado del arte en cada tema de interés. Después de ello, se leyeron los resúmenes y aquellos seleccionados para análisis del texto completo. La literatura relevante se sintetizó, clasificó y organizó en tablas y se presentó al panel de expertos, el cual estaba constituido por 30 profesionales en diferentes áreas. Mediante la metodología Delphi se realizaron 2 rondas de cuestionarios virtuales y una reunión presencial en los cuales se evaluaron los niveles de acuerdo entre los participantes. Los puntos con falta de consenso durante las 2 rondas virtuales se expusieron durante las mesas de discusión en la ronda presencial. La evidencia utilizada se adaptó a las particularidades nacionales según el caso y se aprobó el contenido del documento final. Se propone que estas recomendaciones sean usadas por profesionales de la salud en Colombia.

Congenital transmission of Chagas disease has not been extensively studied in Colombia, and there are no standardized processes in the health system regarding the specific diagnosis, treatment and follow-up of this disease. In order to generate recommendations on congenital Chagas disease and Chagas in women of childbearing age in Colombia, a consensus of experts was developed. An extensive literature search through the Medline database was carried out using the MeSH terms: " Chagas disease/congenital " , " prevention and control " , " diagnosis " , " therapeutics " and " pregnancy " . Appropriate abstracts were selected and the full texts were analyzed. The relevant information was synthesized, classified, and organized into tables and figures and was presented to a panel of experts, which was composed of 30 professionals from various fields. Based on the Delphi methodology, three rounds of consultation were conducted. The first and second rounds were based on electronic questionnaires that measured the level of consensus of each question among the participants. The third round was based on a face-toface discussion focusing on those questions without consensus in the previous consultations. The evidence was adapted to national circumstances on a case-by-case basis, and the content the final document was approved. These recommendations are proposed for use in routine medical practice by health professionals in Colombia.

Glassy states in asymmetric mixtures of soft and hard colloids.

By employing rheological experiments, mode coupling theory, and computer simulations based on realistic coarse-grained models, we investigate the effects of small, hard colloids on the glassy states formed by large, soft colloids. Multiarm star polymers mimic hard and soft colloids by appropriately varying the number and size of their arms. The addition of hard colloids leads, depending on their concentration, to either melting of the soft glass or the emergence of two distinct glassy states. We explain our findings by depletion of the colloids adjacent to the stars, which leads to an arrested phase separation when the repulsive glass line meets the demixing binodal. The parameter-free agreement between experiment, theory, and simulations suggests the generic nature of our results and opens the route for designing soft-hard colloidal composites with tunable rheology.