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

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

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

Earthquake Magnitude and Frequency Forecasting in Northeastern Algeria using Time Series Analysis

This study uses two different time series forecasting approaches (parametric and non-parametric) to assess a frequency and magnitude forecasting of earthquakes above Mw 4.0 in Northeastern Algeria. The Autoregressive Integrated Moving Average (ARIMA) model encompasses the parametric approach, while the non-parametric method employs the Singular Spectrum Analysis (SSA) approach. The ARIMA and SSA models were then used to train and forecast the annual number of earthquakes and annual maximum magnitude events occurring in Northeastern Algeria between 1910 and 2019, including 287 main events larger than Mw 4.0. The SSA method is used as a forecasting algorithm in this case, and the results are compared to those obtained by the ARIMA model. Based on the root mean square error (RMSE) criterion, the SSA forecasting model appears to be more appropriate than the ARIMA model. The consistency between the observation and the forecast is analyzed using a statistical test in terms of the total number of events, denoted as N-test. As a result, the findings indicate that the annual maximum magnitude in Northeastern Algeria between 2020 and 2030 will range from Mw 4.8 to Mw 5.1, while between four and six events with a magnitude of at least Mw 4.0 will occur annually

Seismotectonics zoning of Morocco and adjacent region

In the present work, a new seismotectonics zoning of the Morocco and adjacent region is proposed. It is supported on a new database including recent geological (active faults, slip rates, geometrical characteristics, chronology of some recent tectonic phases) and geophysical (both instrumental and historical seismicity, focal mechanisms, nature of the crust) studies. In addition, the geodynamic context of the convergence of the Africa-Europe plates in the area, going from the Atlantic Ocean to the Mediterranean Sea through the Strait of Gibraltar, has been taken into account. The newly suggested seismotectonics zoning is not limited to the borders of northern Morocco. It considers all the seismic sources (up to 400 km of distance) able to generate large and destructive earthquakes, such as the 1755 Lisbon earthquake, located in the Azores-Gibraltar transforming fault. New catalogues including the historical and instrumental seismicity since 1045 to 2005, and active faults were elaborated and used in this work. The most influential parameters having effects on the definition of the source area characteristics were determined with a suitable accuracy. The new performed zoning includes 12 shallow seismotectonics sources, each one corresponding to a certain volume of the Earth’s crust, whose known data were used to determine its static and dynamic conditions. Each seismotectonics zone has been analysed and interpreted, presenting certain homogeneity in the seismic potential and mode of deformation, obtained from the seismicity data, the strain and the stresses. For zones including faults, we have specified the geometrical characteristics, the chronology of the different movements corresponding to the successive tectonic episodes, and the associated seismicity. This new zoning will provide an improved contribution for both future probabilistic studies on seismic hazard, determining the ground acceleration, and seismic risk in the north of Morocco

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

Energetic and spatial characterization of seismicity in the Algeria–Morocco region

We estimate the energetic and spatial characteristics of seismicity in the Algeria–Morocco region using a variety of seismic and statistical parameters, as a first step in a detailed investigation of regional seismic hazard. We divide the region into five seismotectonic regions, comprising the most important tectonic domains in the studied area: the Moroccan Meseta, the Rif, the Tell, the High Plateau, and the Atlas. Characteristic seismic hazard parameters, including the Gutenberg–Richter b-value, mean seismic activity rate, and maximum possible earthquake magnitude, were computed using an extension of the Aki–Utsu procedure for incomplete earthquake catalogs for each domain, based on recent earthquake catalogs compiled for northern Morocco and northern Algeria. Gutenberg–Richter b-values for each zone were initially estimated using the approach of Weichert (Bull Seismol Soc Am 70:1337–1346, 1980): the estimated b-values are 1.04 ± 0.04, 0.93 ± 0.10, 0.72 ± 0.03, 0.87 ± 0.02, and 0.77 ± 0.02 for the Atlas, Meseta, High Plateau, Rif, and Tell seismogenic zones, respectively. The fractal dimension D2 was also estimated for each zone. From the ratio D2/b, it appears that the Tell and Rif zones, with ratios of 2.09 and 2.12, respectively, have the highest potential earthquake hazard in the region. The Gutenberg–Richter relationship analysis allows us to derive that in the Tell and Rif, the number of earthquake with magnitude above Mw 4.0, since 1925 normalized to decade and to square cell with 100-km sides is equal to 2.6 and 1.91, respectively. This study provides the first detailed information about the potential seismicity of these large domains, including maximum regional magnitudes, characteristics of spatial clustering, and distribution of seismic energy release.The Algerian CRAAG, the Spanish Seismic Hazard and Active Tectonics research group, and the Spanish MINECO CGL2015- 65602-R project.http://link.springer.com/journal/110692018-04-30hb2016Physic

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