Microcanonical versus Canonical Analysis of Protein Folding

The microcanonical analysis is shown to be a powerful tool to characterize the protein folding transition and to neatly distinguish between good and bad folders. An off-lattice model with parameter chosen to represent polymers of these two types is used to illustrate this approach. Both canonical and microcanonical ensembles are employed. The required calculations were performed using parallel tempering Monte Carlo simulations. The most revealing features of the folding transition are related to its first-order-like character, namely, the S-bend pattern in the caloric curve, which gives rise to negative microcanonical specific heats, and the bimodality of the energy distribution function at the transition temperatures. Models for a good folder are shown to be quite robust against perturbations in the interaction potential parameters.Comment: 4 pages, 4 figure

Kinematic study of planetary nebulae in NGC 6822

By measuring precise radial velocities of planetary nebulae (which belong to the intermediate age population), H II regions, and A-type supergiant stars (which are members of the young population) in NGC 6822, we aim to determine if both types of population share the kinematics of the disk of H I found in this galaxy. Spectroscopic data for four planetary nebulae were obtained with the high spectral resolution spectrograph Magellan Inamori Kyocera Echelle (MIKE) on the Magellan telescope at Las Campanas Observatory. Data for other three PNe and one H II region were obtained from the SPM Catalog of Extragalactic Planetary Nebulae which employed the Manchester Echelle Spectrometer attached to the 2.1m telescope at the Observatorio Astron\'omico Nacional, M\'exico. In the wavelength calibrated spectra, the heliocentric radial velocities were measured with a precision better than 5-6 km s$^{-1}$. Data for three additional H II regions and a couple of A-type supergiant stars were collected from the literature. The heliocentric radial velocities of the different objects were compared to the velocities of the H i disk at the same position. From the analysis of radial velocities it is found that H II regions and A-type supergiants do share the kinematics of the H I disk at the same position, as expected for these young objects. On the contrary, planetary nebula velocities differ significantly from that of the H I at the same position. The kinematics of planetary nebulae is independent from the young population kinematics and it is closer to the behavior shown by carbon stars, which are intermediate-age members of the stellar spheroid existing in this galaxy. Our results are confirming that there are at least two very different kinematical systems in NGC 6822

Forage Yield and Quality of Signal Grass-Clitoria Mixture Grazed at Different Frequencies

A Signal grass-Clitoria mixture provides good quality forage in the dry tropic of southern Mexico. Grazing frequency is a management tool that determines yield, botanical components and quality of pastures. The objective of this study was to determine forage yield, quality and botanical components in a Signal grass (Brachiaria decumbens)-Clitoria (Clitoria ternatea) mixture when grazed at different frequencies

Yield Components in a Signal Grass-Clitoria Mixture Grazed at Different Herbage Allowance

A Signal grass-Clitoria mixture provides good quality forage in the dry tropic of southern Mexico. However, its response in leaf and stem yields to grazing at different daily herbage allowances is not well documented. The objective of this study was to determine available and residual leaf and stem yields in a Signal grass (Brachiaria decumbens)-Clitoria (Clitoria ternatea) mixture grazed at different daily herbage allowance

Hospitalizations and mortality of patients with heart failure in the COVID-19 era in Peru

Objectives: The worldwide heart failure (HF) prevalence is 8.52 per 1000 inhabitants, with a global economic burden of 346.17 billion dollars. With the COVID-19 pandemic, the focus of medical care has changed to treating the morbidity and mortality of patients with COVID-19 and reducing medical procedures or visits to patients with HF, with the impact being greater in low- and middle-income countries. Methods: We performed an interrupted time series analysis of HF to determine the changes in the trend of hospitalizations and in-hospital mortality of HF patients before and after the mandatory lockdown in Peru. Results: A total of 18,514 adults were included in the analysis. Monthly hospital admissions immediately decreased by 599 (95% confidence interval [CI]: 113 to 1085) and the difference in slope before and after the lockdown was 6.4 hospital admissions (95% CI: −4 to 18). In-hospital mortality increased by 18% (95% CI: −8%–43%) and the difference in slope before and after the lockdown was −0.3% (95% CI: −0.9%–0.25%). Conclusions: There was a reduction in hospitalizations and an increase in the in-hospital mortality of patients with HF before and after the mandatory lockdown due to the COVID-19 pandemic in Peru.Revisión por pare

Effects of trapping site on the spectroscopy of 1P1 excited group 12 metal atoms in rare gas matrices

A molecular dynamics deposition model has been used to simulate the growth of rare gas matrices doped with atoms of the group 12 elements zinc, cadmium and mercury. This study investigates the sites occupied by Zn, Cd and Hg metal atoms when isolated in the solid rare gases. To probe the results, the resonance 1 P 1-1 S 0 transitions of the matrix-isolated metal atoms were calculated and compared with the recorded spectra of the M/RG solids. The theoretical spectroscopy obtained in this work was generated using the molecular dynamics with quantum transitions method. In Ne matrices the metal atoms preferably occupy tetra- and hexa-vacancy sites while in the case of Xe matrices, only the single vacancy site is formed. For Ar and Kr matrices Zn but especially Cd can be trapped in tetra- and hexa-vacancy sites in addition to single-vacancy sites, while Hg atoms show exclusive occupancy in single vacancy sites.Fil: Lara Moreno, M.. Universidad de La Habana; Cuba. Instituto Superior de Tecnologías y Ciencias Aplicadas.; Cuba. Université de Bordeaux; Francia. Centre National de la Recherche Scientifique; FranciaFil: Alvarez Hernández, J.. Universidad de La Habana; Cuba. Instituto Superior de Tecnologías y Ciencias Aplicadas.; Cuba. University of Rochester. Department of Chemistry; Estados UnidosFil: Negrín Yuvero, Lázaro Hassiel. Universidad de La Habana; Cuba. Instituto Superior de Tecnologías y Ciencias Aplicadas.; Cuba. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: McCaffrey, J. G.. National University of Ireland. Maynooth University. Department of Chemistry; IrlandaFil: Rojas Lorenzo, G.. Universidad de La Habana; Cuba. Instituto Superior de Tecnologías y Ciencias Aplicadas.; Cub

Examination of the Feynman-Hibbs Approach in the Study of NeN_N-Coronene Clusters at Low Temperatures

Feynman-Hibbs (FH) effective potentials constitute an appealing approach for investigations of many-body systems at thermal equilibrium since they allow us to easily include quantum corrections within standard classical simulations. In this work we apply the FH formulation to the study of Ne$_N$-coronene clusters ($N=$ 1-4, 14) in the 2-14 K temperature range. Quadratic (FH2) and quartic (FH4) contributions to the effective potentials are built upon Ne-Ne and Ne-coronene analytical potentials. In particular, a new corrected expression for the FH4 effective potential is reported. FH2 and FH4 cluster energies and structures -obtained from energy optimization through a basin-hoping algorithm as well as classical Monte Carlo simulations- are reported and compared with reference path integral Monte Carlo calculations. For temperatures $T> 4$ K, both FH2 and FH4 potentials are able to correct the purely classical calculations in a consistent way. However, the FH approach fails at lower temperatures, especially the quartic correction. It is thus crucial to assess the range of applicability of this formulation and, in particular, to apply the FH4 potentials with great caution. A simple model of $N$ isotropic harmonic oscillators allows us to propose a means of estimating the cut-off temperature for the validity of the method, which is found to increase with the number of atoms adsorbed on the coronene molecule

Prevalence of Resistant Strains of Rhipicephalus microplus to Acaricides in Cattle Ranch in the Tropical Region of Tecpan of Galeana, Guerrero, Mexico

Tick and tick borne diseases cause many problems to the cattle industry worldwide. The prevalence of resistant strains of Rhipicephalus microplus to different acaricides on cattle farms in the tropical region of Tecpan of Galeana, Guerrero, Mexico, and risk factors related to prevalence of resistant strains of R. microplus. Sixty one ranches infested were sampled; in each ranch were collected 30-50 fully-engorged female R. microplus ticks, of 10 cattle randomly selected, and evaluated in their progeny resistance to acaricides, using the larval packet test. The prevalence of resistant strains was total pyrethroids and amitraz. In organophosphorus 31.1, 48.3 and 82.2% of strains were resistant to clorpyriphos, coumaphos and diazinon, respectively. Risk factors favored (P<0.05) the development of resistant strains of acaricides. We concluded that the resistance of R. microplus to acaricides used to control a problem, and risk factors (livestock management) have accelerated the development of resistance