Kinetically driven helix formation during the homopolymer collapse process

Using Langevin simulations, we find that simple 'generic' bead-and-spring homopolymer chains in a sufficiently bad solvent spontaneously develop helical order during the process of collapsing from an initially stretched conformation. The helix formation is initiated by the unstable modes of the straight chain, which drive the system towards a long-lived metastable transient state. The effect is most pronounced if hydrodynamic interactions are screened.Comment: 4 pages, 4 figure

Global weak solutions to magnetic fluid flows with nonlinear Maxwell-Cattaneo heat transfer law

28We discuss the equations describing the dynamic of the heat transfer in a magnetic fluid flow under the action of an applied magnetic field. Instead of the usual heat transfer equation we use a generalization given by the Maxwell-Cattaneo law which is a system satisfied by the temperature and the heat flux. We prove a global existence of weak solutions to the system having a finite energy

Seismic Hazard Assessment and Its Uncertainty for the Central Part of Northern Algeria

This study presents a probabilistic seismic hazard assessment for the central part of northern Algeria using two complementary seismic models: a fault-based model and a gridded seismicity model. Two ground-motion attenuation equations were chosen using the Pacific Earthquake Engineering Research Center Next-Generation models, as well as local and regional ones. The ranking method was used to assess their ability to gather accurate data. To account for epistemic uncertainty in both components of the assessment, the seismic hazard was computed using a logic tree approach. Expert judgment and data testing were used to evaluate the weights assigned to individual ground-motion prediction equations. The seismic hazard maps depicted the obtained results in terms of spectral accelerations at oscillation periods of 0.0, 0.2, and 1.0 s, with 10% and 5% probabilities of exceedance in 50 years, and for soil types B, B/C, C, and C/D, as defined by the National Earthquake Hazards Reduction Program. From the analysis, the uncertainty is expressed as both a 95% confidence band and the coefficient of variation (COV). Annual frequencies of exceedance and hazard curves were estimated for the selected cities, as well as uniform hazard spectra for the previously quoted probabilities of exceedance and the soil types considered. Peak ground acceleration values of 0.44±0.17 g and 0.38±0.06 g were reported for the B/C soil type in the cities of Algiers and Blida, respectively, for a return period of 475 years. Seismic maps for the selected return periods depicting the classification of the estimated values are also displayed in terms of very high, high, medium, low and very low degrees of reliability. Furthermore, a seismic hazard disaggregation analysis in terms of magnitude, distance, and azimuth was carried out. The primary goal of such analyses is to determine the relative contribution of different seismic foci and sources to seismic hazard at specific locations. Thus, for each studied city, for the considered return periods and for the soil type B/C, the so-called control or modal earthquake was estimated. At Algiers, events with magnitudes Mw 5.0–5.5 and distances of less than 10 km contribute the most to the mean seismic hazard over a 475-year period. However, for the same return period, those events with Mw 7.0–7.5 and located between 10 and 20 km away contribute the most to the seismic hazard at Tipaza

Stochastic Modeling of the Al Hoceima (Morocco) Aftershock Sequences of 1994, 2004 and 2016

The three aftershock sequences that occurred in Al Hoceima, Morocco, in May 1994 (Mw 6.0), February 2004 (Mw 6.4) and January 2016 (Mw 6.3) were stochastically modeled to investigate their temporal and energetic behavior. A form of the restricted trigger model known as the restricted epidemic type aftershock sequence (RETAS) was used for the temporal analysis of the selected series. The best-determined fit models for each sequence differ based on the Akaike information criteria. The revealed discrepancies suggest that, although the activated fault systems are close (within 10 to 20 km), their stress regimes change and shift across each series. In addition, a stochastic model was presented to study the strain release following a specific strong earthquake. This model was constructed using a compound Poisson process and depicted the progression of the strain release during the aftershock sequence. The proposed model was then applied to the data. After the RETAS model was used to evaluate the behavior of the aftershock decay rate, the best-fit model was obtained and integrated into the strain-release stochastic analysis. By detecting the potential disparities between the observed data and model, the applied stochastic model of strain release allows for a more comprehensive examination. Furthermore, comparing the observed and expected cumulative energy release numbers revealed some variations at the start of all three sequences. This demonstrates that significant aftershock clusters occur more frequently shortly after the mainshock at the start of the sequence rather than if they are assumed to occur randomly.Consejeria de Economia, Conocimiento, Empresa y Universidad, in the frame of the Programa Operativo FEDER Andalucia Junta de Andalucia CGL2016-80687-R B-RNM-301UGR18 RNM148 P18-RT-327

Comparative genome analysis of Bacillus spp. and its relationship with bioactive nonribosomal peptide production

Bacillus genus comprises an important number of species which produce a wide range of secondary metabolites displaying a broad spectrum of activity and great structural diversity. The genome sequences of an important number of species have been published and a large number of orphan genes reported. This review, covering all the literature in this field up to end of 2011, summarizes and compares the genetic potential of these organisms from the point of view of bioactive nonribosomal peptide production and their application as antibiotics, plant pathogen biocontrol, promotion of plant growth, etc. The biological and structural studies of the peptides isolated from Bacillus species are revised and some aspects of the biosynthesis of these metabolites and related compounds are discussed

Global Newtonian limit for the Relativistic Boltzmann Equation near Vacuum

We study the Cauchy Problem for the relativistic Boltzmann equation with near Vacuum initial data. Unique global in time "mild" solutions are obtained uniformly in the speed of light parameter $c \ge 1$. We furthermore prove that solutions to the relativistic Boltzmann equation converge to solutions of the Newtonian Boltzmann equation in the limit as $c\to\infty$ on arbitrary time intervals $[0,T]$, with convergence rate $1/c^{2-\epsilon}$ for any $\epsilon \in(0,2)$. This may be the first proof of unique global in time validity of the Newtonian limit for a Kinetic equation.Comment: 35 page

Distributional and classical solutions to the Cauchy Boltzmann problem for soft potentials with integrable angular cross section

This paper focuses on the study of existence and uniqueness of distributional and classical solutions to the Cauchy Boltzmann problem for the soft potential case assuming $S^{n-1}$ integrability of the angular part of the collision kernel (Grad cut-off assumption). For this purpose we revisit the Kaniel--Shinbrot iteration technique to present an elementary proof of existence and uniqueness results that includes large data near a local Maxwellian regime with possibly infinite initial mass. We study the propagation of regularity using a recent estimate for the positive collision operator given in [3], by E. Carneiro and the authors, that permits to study such propagation without additional conditions on the collision kernel. Finally, an $L^{p}$-stability result (with $1\leq p\leq\infty$) is presented assuming the aforementioned condition.Comment: 19 page