Simulating the city traffic complexity induced by traffic light periods.

We revisited the global traffic light optimization problem through a cellular automata model, which allows us to address the relationship between the traffic lights and car routing. We conclude that both aspects are not separable. Our results show that a good routing strategy weakens the importance of the traffic light period for mid-densities, thus limiting the parameter space where such optimization is relevant. This is confirmed by analyzing the travel time normalized by the shortest path between the origin and destination. As an unforeseen result, we report what seems to be a power-law distribution for such quantities, indicating that the travel time distribution slowly decreases for long travel times. The power-law exponent depends on the density, traffic light period, and routing strategy, which in this case is parametrized by the tendency of agents to abandon a route if it becomes stagnant. These results could have relevant consequences on how to improve the overall traffic efficiency in a particular city, thus providing insight into useful measurements, which are often counter-intuitive, which may be valuable to traffic controllers that operate through traffic light periods and phases.

Does following optimized routes for single cars improve car routing?

We study the impact of deserting a pre-established path, determined by a navigation software, on the overall city traffic. To do so, we consider a cellular automaton model for vehicular traffic, where the cars travel between two randomly assigned points in the city following three different navigation strategies based on the minimization of the individual paths or travel times. We found, in general, that, above a critical car density, the transport improves in all strategies if we decrease the time that the vehicles persist in trying to follow a particular strategy when a route is blocked, namely, the mean flux increases, the individual travel times decrease, and the fluctuations of density in the streets decrease; consequently, deserting helps prevent traffic jams.

Solar wind thermally induced magnetic fluctuations.

A kinetic description of Alfvén-cyclotron magnetic fluctuations for anisotropic electron-proton quasistable plasmas is studied. An analytical treatment, based on the fluctuation-dissipation theorem, consistently shows that spontaneous fluctuations in plasmas with stable distributions significantly contribute to the observed magnetic fluctuations in the solar wind, as seen, for example, in [S. D. Bale et al., Phys. Rev. Lett. 103, 211101 (2009)], even far below from the instability thresholds. Furthermore, these results, which do not require any adjustable parameters or wave excitations, are consistent with the results provided by hybrid simulations. It is expected that this analysis contributes to our understanding of the nature of magnetic fluctuations in the solar wind.

Pedestrian flow in two dimensions: Optimal psychological stress leads to less evacuation time and decongestion.

Collective motion is an innate ability of all living systems, which depends on physiological and psychosocial factors in the case of humans. Such a collective organization is becoming of great interest in collective motion in human crowds. Using a cellular automaton (CA) simulation model, we demonstrate that emergency egress from a two-dimensional corridor with optimal stress leads to less evacuation time and efficient mass evacuations. We study how three types of stress (i.e., mild stress, optimal stress, and anxiety) described in the literature have a significant impact on the collective dynamics. We found that low-stress levels could decrease the evacuation time in an entire occupied room since agents choose alternative routes rather than the shortest path to the exit and display cooperative behavior. Therefore, the combination of mild and optimal stress can lead to efficient evacuations. Also CA simulations may be used to find safer and more efficient ways to conduct mass evacuation procedures.

Characterization of the nontrivial and chaotic behavior that occurs in a simple city traffic model.

We explore in detail the nontrivial and chaotic behavior of the traffic model proposed by Toledo et al. [Phys. Rev. E 70, 016107 (2004)] due to the richness of behavior present in the model, in spite of the fact that it is a minimalistic representation of basic city traffic dynamics. The chaotic behavior, previously shown for a given lower bound in acceleration/brake ratio, is examined more carefully and the region in parameter space for which we observe this nontrivial behavior is found. This parameter region may be related to the high sensitivity of traffic flow that eventually leads to traffic jams. Approximate scaling laws are proposed.

Magnetostatic interaction between two bubble skyrmions.

A detailed analytic and numerical analysis of the interaction between two bubble skyrmions has been carried out. The results from the micromagnetic calculations show that when the skyrmions are in the same plane, the magnetic parameters vary weakly as a function of the separation between them. On the other hand, when the skyrmions are located in the same vertical axis, the magnetic parameters show a strong variation as a function of the separation of the skyrmions. In particular, when a magnetic disk is over another, there is a transition from a Bloch-like skyrmion configuration to a Néel-like skyrmion configuration as the distance between the disks decreases, as a consequence of the magnetostatic interaction. Therefore, it is possible to stabilize a bubble skyrmion with a Néel configuration without the Dzyaloshinskii-Moriya interaction. Thus, these results can be used for the control of the skyrmion parameters in magnetic spintronic devices that need to use these configurations.

Knowledge, attitude, and practice regarding COVID-19 outbreak in Bangladesh: An online-based cross-sectional study.

In Bangladesh, an array of measures have been adopted to control the rapid spread of the COVID-19 epidemic. Such general population control measures could significantly influence perception, knowledge, attitudes, and practices (KAP) towards COVID-19. Here, we assessed KAP towards COVID-19 immediately after the lock-down measures were implemented and during the rapid rise period of the outbreak. Online-based cross-sectional study conducted from March 29 to April 19, 2020, involving Bangladeshi residents aged 12-64 years, recruited via social media. After consenting, participants completed an online survey assessing socio-demographic variables, perception, and KAP towards COVID-19. Of the 2017 survey participants, 59.8% were male, the majority were students (71.2%), aged 21-30 years (57.9%), having a bachelor's degree (61.0%), having family income >30,000 BDT (50.0%), and living in urban areas (69.8). The survey revealed that 48.3% of participants had more accurate knowledge, 62.3% had more positive attitudes, and 55.1% had more frequent practices regarding COVID-19 prevention. Majority (96.7%) of the participants agreed 'COVID-19 is a dangerous disease', almost all (98.7%) participants wore a face mask in crowded places, 98.8% agreed to report a suspected case to health authorities, and 93.8% implemented washing hands with soap and water. In multiple logistic regression analyses, COVID-19 more accurate knowledge was associated with age and residence. Sociodemographic factors such as being older, higher education, employment, monthly family income >30,000 BDT, and having more frequent prevention practices were the more positive attitude factors. More frequent prevention practice factors were associated with female sex, older age, higher education, family income > 30,000 BDT, urban area residence, and having more positive attitudes. To improve KAP of general populations is crucial during the rapid rise period of a pandemic outbreak such as COVID-19. Therefore, development of effective health education programs that incorporate considerations of KAP-modifying factors is needed.

New variants of polar glycopeptidolipids detected in Mycobacterium simiae, including 'habana' strains, as evidenced by electrospray ionization-ion trap-mass spectrometry.

AIMS: To determine the composition of polar glycopeptidolipids (pGPLs) of Mycobacterium simiae and, particularly, those of 'habana' strains, in a search for specific markers given the immunogenic potential of 'habana' TMC 5135 in experimental tuberculosis. METHODS AND RESULTS: pGPLs were determined in free lipid extracts using electrospray ionization-ion trap-mass spectrometry (ESI-IT-MS), working in both negative- and positive-ion mode. In the case of TMC 5135, the presence of the previously characterized GPL-II (containing 2,4-di-O-CH(3) glucuronic acid as distal sugar in the oligosaccharide antigenic moiety) and GPL-III (containing 4-O-CH(3) glucuronic acid as distal sugar) was confirmed using MS/MS and MS/MS/MS approaches. Interestingly, some 'habana' strains presented variants of GPL-II, designated GPL-II'-A and GPL-II'-B. A di-O-CH(3)-deoxy-hexose (tentatively, 2,3-di-O-CH(3)-fucose) was identified as the penultimate sugar in the oligosaccharide moiety of GPL-II'-A, whereas in GPL-II'-B the penultimate sugar was fucose (tentative identification). On the contrary, the distal sugar of the oligosaccharide chain of pGPLs of Myco. simiae ATCC 25275(T) was identified as tri-O-CH(3)-glucuronic acid (designated GPL-sim(T)-I, with two variants: GPL-sim(T)-I-A and GPL-sim(T)-I-B), O-CH(3)-glucuronic acid (designated GPL-sim(T)-II) and di-O-CH(3)-glucuronic acid (GPL-II'-A and GPL-II'-B). The penultimate sugar of the oligosaccharide chain of GPL-sim(T)-I-A and GPL-sim(T)-II was identified as di-O-CH(3)-deoxy-hexose (tentatively, 2,3-di-O-CH(3) fucose), and that of GPL-sim(T)-I-B as deoxy-hexose (tentatively, fucose). In all strains studied, each [M-H](-) and [M+Na](+) ion was revealed as a mixture of homologous compounds varying in the number of -O-CH(3) groups present in the oligosaccharide moiety and in the length of the fatty acyl linked to the peptide. CONCLUSIONS: The present work indicates that, within a similar general pattern of pGPLs, different strains of Myco. simiae present some variations, so that new compounds (GPL-II'-A, GPL-II'-B, GPL-sim(T)-I-A, GPL-sim(T)-I-B and GPL-sim(T)-II) were defined. Noteworthy was the fact that the 'habana' strains clearly differed from the type strain of Myco. simiae. SIGNIFICANCE AND IMPACT OF THE STUDY: The data obtained can be used in the delineation of the 'habana' group of Myco. simiae, including the quality control of the immunogenic strain 'habana' TMC 5135.

Optimal control in a noisy system.

We describe a simple method to control a known unstable periodic orbit (UPO) in the presence of noise. The strategy is based on regarding the control method as an optimization problem, which allows us to calculate a control matrix A. We illustrate the idea with the Rossler system, the Lorenz system, and a hyperchaotic system that has two exponents with positive real parts. Initially, a UPO and the corresponding control matrix are found in the absence of noise in these systems. It is shown that the strategy is useful even if noise is added as control is applied. For low noise, it is enough to find a control matrix such that the maximum Lyapunov exponent lambda(max)<0, and with a single non-null entry. If noise is increased, however, this is not the case, and the full control matrix A may be required to keep the UPO under control. Besides the Lyapunov spectrum, a characterization of the control strategies is given in terms of the average distance to the UPO and the control effort required to keep the orbit under control. Finally, particular attention is given to the problem of handling noise, which can affect considerably the estimation of the UPO itself and its exponents, and a cleaning strategy based on singular value decomposition was developed. This strategy gives a consistent manner to approach noisy systems, and may be easily adapted as a parametric control strategy, and to experimental situations, where noise is unavoidable.

Universal and nonuniversal features in a model of city traffic.

The complex behavior that occurs when traffic lights are synchronized is studied. Two strategies are considered: all lights in phase, and a "green wave" with a propagating green signal. It is found that traffic variables such as traveling time, velocity, and fuel consumption, near resonance, follow critical scaling laws. For the green wave, it is shown that time and velocity scaling laws hold even for random separation between traffic lights. These results suggest the concept of transient resonances, which can be induced by adaptively changing the phase of traffic lights. This may be important to consider when designing strategies for traffic control in cities, where short trajectories, and thus transient solutions, are likely to be relevant.

Lipids of 'Mycobacterium habana', a synonym of Mycobacterium simiae with vaccine potential.

'Mycobacterium habana' was proposed as a distinct species within the genus Mycobacterium; however, it is actually a synonym of Mycobacterium simiae and included in the serotype I of this species. The potential use of 'M. habana' as a vaccine in both leprosy and tuberculosis has led to the analysis of its lipid composition in an attempt to define distinctive markers that could be used in the quality control of true strains of this bacterium. Lipids of taxonomic value (fatty and mycolic acids) are similar in 'M. habana' and M. simiae; nevertheless, they clearly differ on the basis of glycopeptidolipid (GPL) composition. Thus, contrary to M. simiae, most strains of 'M. habana' can be defined by the presence of three polar compounds, designated GPL-I, GPL-II and GPL-III, easily determined by thin-layer chromatography, and characterized, respectively, by the content of l-fucose, 2,4-di-O-Me-d-glucuronic acid, and 4-O-Me-d-glucuronic acid, as epitopes.

Minimally invasive vein harvest and wound healing using the SaphLITE Retractor System.

BACKGROUND: In response to reported wound complication rates of 19% to 43% for traditional saphenous vein harvest, several minimally invasive vein harvest (MIVH) techniques have been developed. The purpose of this investigation is to determine the effectiveness of one such MIVH technology, the Genzyme SaphLITE Retractor System (Genzyme Biosurgery, Cambridge, MA). METHODS: Since May 2000, saphenectomy was undertaken in 305 coronary artery bypass graft (CABG) patients using SaphLITE in a prospective, nonrandomized trial at three centers. Patients were assessed for wound healing (ASEPSIS tool) and incisional pain (numeric scale) through the postoperative visit. Harvest times, incision lengths, and vein lengths were recorded. RESULTS: ASEPSIS indicated satisfactory healing in 96.0%. Infection rate was 1.3% with four patients requiring antibiotics and debridement of one incision. Of hospitalized patients, 85.4% had no or minimal affected leg pain. Additional mean data include: harvest time 43.4 +/- 17.6 minutes, incision number 3.0 +/- 1.2, incision length 2.9 +/- 1.4 cm, and vein length 46.0 +/- 15.2 cm. CONCLUSIONS: SaphLITE provides an effective alternative to traditional saphenous vein harvest, with improved wound healing, decreased pain, and acceptable harvest times.

Molecular epidemiology of tuberculosis in Cuba outside of Havana, July 1994-June 1995: utility of spoligotyping versus IS6110 restriction fragment length polymorphism.

SETTING: Molecular typing has become an important tool for examining the extent of active transmission of tuberculosis. OBJECTIVES: To examine transmission of tuberculosis in Cuba using IS6110 restriction fragment length polymorphism (RFLP) typing and to evaluate the utility of spoligotyping. DESIGN: One hundred and sixty Mycobacterium tuberculosis strains isolated over a one year period in Cuba were subjected to RFLP and spoligotyping. RESULTS: Forty-eight percent of the isolates were found in 19 clusters of strains with identical RFLP patterns. In general, cluster sizes were limited, except for two large institutional outbreaks. Age was strongly inversely correlated to clustering. Most streptomycin-resistant isolates were found in clusters. Fifteen spoligotype clusters comprised 78% of the isolates. Significantly different IS6110 RFLP types subdivided 11 spoligotype clusters, whereas none of the IS6110 clusters were subdivided by spoligotyping. CONCLUSIONS: Considering the short study period, 48% clustering is high, indicating that recent transmission plays an important role in Cuba. Although resistance is still a minor problem, transmission of streptomycin-resistant strains occurs. The high polymorphism observed with IS6110 RFLP indicates that this marker is useful for future molecular epidemiological studies in Cuba. Spoligotyping appeared less suitable for population-based studies.

Molecular epidemiological study on transmission of tuberculosis in a hospital for mentally handicapped patients in Havana, Cuba.

The IS 6110 restriction fragment length polymorphism (RFLP) analysis of Mycobacterium tuberculosis isolates has revolutionized the description of the epidemiology of tuberculosis. This technique has been used to confirm suspected cases of transmission in several institutional settings. In this study, we analysed by conventional and molecular epidemiological methods the unexpectedly high number of tuberculosis cases which occurred among 14 mentally handicapped patients and a healthcare worker in Havana's Psychiatric Hospital in the period from 1995 to 1998. Twelve M. tuberculosis isolates of the respective patients showed the same DNA fingerprint, consisting of nine bands. Three other different IS 6110 RFLP patterns with 10, eight, and 10 bands were observed. The results of RFLP analysis and of an additional epidemiological investigation allowed the identification of the probable source of this chain of transmission in the healthcare facility. This would not have been possible without the aid of DNA fingerprinting. Delays in diagnosis of the source patient and of the secondary cases, a tardy and deficient tuberculin skin test and the difficulties of management of mentally handicapped patients probably contributed to spread the M. tuberculosis strain in Havana's Psychiatric Hospital.

Modeling traffic through a sequence of traffic lights.

We introduce a microscopic traffic model, based on kinematic behavior, which consists of a single vehicle traveling through a sequence of traffic lights that turn on and off with a specific frequency. The reconstructed function that maps the state of the vehicle from light to light displays complex behavior for certain conditions. This chaotic behavior, which arises by the discontinuous nature of the map, displays an essential ingredient in traffic patterns and could be of relevance in studying traffic situations.

Self-modulation of nonlinear Alfvén waves in a strongly magnetized relativistic electron-positron plasma.

We study the self-modulation of a circularly polarized Alfvén wave in a strongly magnetized relativistic electron-positron plasma with finite temperature. This nonlinear wave corresponds to an exact solution of the equations, with a dispersion relation that has two branches. For a large magnetic field, the Alfvén branch has two different zones, which we call the normal dispersion zone (where dω/dk>0) and the anomalous dispersion zone (where dω/dk<0). A nonlinear Schrödinger equation is derived in the normal dispersion zone of the Alfvén wave, where the wave envelope can evolve as a periodic wave train or as a solitary wave, depending on the initial condition. The maximum growth rate of the modulational instability decreases as the temperature is increased. We also study the Alfvén wave propagation in the anomalous dispersion zone, where a nonlinear wave equation is obtained. However, in this zone the wave envelope can evolve only as a periodic wave train.

Wavelet-based multifractal analysis of nonlinear time series: the earthquake-driven tsunami of 27 February 2010 in Chile.

We study general multifractal properties of tidal gauge and long-wave time series which show a well defined transition between two states, as is the case of sea level when a tsunami arrives. We adopt a method based on discrete wavelets, called wavelet leaders, which has been successfully used in a wide range of applications from image analysis to biomedical signals. First, we analyze an empirical time series of tidal gauge from the tsunami event of 27 February 2010 in Chile. Then, we study a numerical solution of the driven-damped regularized long-wave equation (RLWE) which displays on-off intermittency. Both time series are characterized by a sudden change between two sharply distinct dynamical states. Our analysis suggests a correspondence between the pre- and post-tsunami states (ocean background) and the on state in the RLWE, and also between the tsunami state (disturbed ocean) and the off state in the RLWE. A qualitative similarity in their singularity spectra is observed, and since the RLWE is used to model shallow water dynamics, this result could imply an underlying dynamical similarity.

Resonance, criticality, and emergence in city traffic investigated in cellular automaton models.

The complex behavior that occurs when traffic lights are synchronized is studied for a row of interacting cars. The system is modeled through a cellular automaton. Two strategies are considered: all lights in phase and a "green wave" with a propagating green signal. It is found that the mean velocity near the resonant condition follows a critical scaling law. For the green wave, it is shown that the mean velocity scaling law holds even for random separation between traffic lights and is not dependent on the density. This independence on car density is broken when random perturbations are considered in the car velocity. Random velocity perturbations also have the effect of leading the system to an emergent state, where cars move in clusters, but with an average velocity which is independent of traffic light switching for large injection rates.

[Mycobacterium cubense. A new pigmented species of slow growth]. / Mycobacterium cubense. Nueva especie pigmentada y de crecimiento lento.

The isolation of an acid-fast microorganism of the genus Mycobacterium is reported. Its most relevant characteristics are the intense red color and the initial spheric shape of colonies which furtherly evolve to a peculiar division. The biochemical products from test bacteria as niacin, nitrase, lipase, phosphatase, TCH, catalase, peroxidase and a series of 11 amides as well as the tests for susceptibility against antibacillary drugs and biological tests are described. The patterns obtained permit the characterization of this species as one non previously described. The name Mycobacterium cubense, n. sp. is suggested.

[Evaluation of an ELISA for the serologic diagnosis of tuberculosis]. / Evaluación de un ELISA para el diagnóstico serológico de tuberculosis.

The use of an ELISA method for the serological diagnosis of tuberculosis was assessed through the study of the presence of circulating IgG antibodies to PPD in 220 serum samples. An 82% sensibility was determined in 50 serum samples from patients with pulmonary tuberculosis, and a specificity of 95.33% in 150 serum samples from apparently healthy subjects. 20 serum samples from patients with disorders other than tuberculosis were included in the study to determine possible cross reactions.