Modelling Nonlinear Sequence Generators in terms of Linear Cellular Automata

In this work, a wide family of LFSR-based sequence generators, the so-called Clock-Controlled Shrinking Generators (CCSGs), has been analyzed and identified with a subset of linear Cellular Automata (CA). In fact, a pair of linear models describing the behavior of the CCSGs can be derived. The algorithm that converts a given CCSG into a CA-based linear model is very simple and can be applied to CCSGs in a range of practical interest. The linearity of these cellular models can be advantageously used in two different ways: (a) for the analysis and/or cryptanalysis of the CCSGs and (b) for the reconstruction of the output sequence obtained from this kind of generators.Comment: 15 pages, 0 figure

Constraints on Inflation in Einstein-Brans-Dicke Frame

The density perturbation during inflation seeds the large scale structure. We consider both new inflation-type and chaotic inflation-type potentials in the framework of Einstein-Brans-Dicke gravity. The density perturbation gives strong constraints on the parameters in these potentials. For both potentials, the constraints are not much different from those obtained in the original inflationary models by using of Einstein gravity.Comment: 6 pages, Revtex file, typos adde

Influence of transport and ocean ice extent on biogenic aerosol sulfur in the Arctic atmosphere

The recent decline in sea ice cover in the Arctic Ocean could affect the regional radiative forcing via changes in sea ice-atmosphere exchange of dimethyl sulfide (DMS) and biogenic aerosols formed from its atmospheric oxidation, such as methanesulfonic acid (MSA). This study examines relationships between changes in total sea ice extent north of 70 degrees N and atmospheric MSA measurement at Alert, Nunavut, during 1980-2009; at Barrow, Alaska, during 1997-2008; and at Ny-Alesund, Svalbard, for 1991-2004. During the 1980-1989 and 1990-1997 periods, summer (July-August) and June MSA concentrations at Alert decreased. In general, MSA concentrations increased at all locations since 2000 with respect to 1990 values, specifically during June and summer at Alert and in summer at Barrow and Ny-Alesund. Our results show variability in MSA at all sites is related to changes in the source strengths of DMS, possibly linked to changes in sea ice extent as well as to changes in atmospheric transport patterns. Since 2000, a late spring increase in atmospheric MSA at the three sites coincides with the northward migration of the marginal ice edge zone where high DMS emissions from ocean to atmosphere have previously been reported. Significant negative correlations are found between sea ice extent and MSA concentrations at the three sites during the spring and June. These results suggest that a decrease in seasonal ice cover influencing other mechanisms of DMS production could lead to higher atmospheric MSA concentrations

Development of polyamide 6 based single polymer composites reinforced by novel stitched plain fabrics

In the present study, novel woven reinforced single polymer composites (WSPC) based on polyamide 6 (PA6) is developed via a combination of powder-coating of PA6 textile reinforcements with PA6 empty microcapsules (EMC) and compression molding techniques. Activated anionic ring-opening polymerization of ε-caprolactam was employed to synthesize the PA6-EMC which was transformed during the compression molding into WSPC matrix without damaging the PA6 textile reinforcements. A promising novel class of PA6 woven fabrics, stitched plain, which are patented by Jakob Müller company AG® were used as reinforcements. The tensile properties of stitched plain reinforced WSPC were studied and compared to ones reinforced by the plain-woven structure and the PA6 neat matrix reference materials. The parametric studies are performed on the stress field along the elements of reinforcements, using image processing to correlate the influence of reinforcement architectures with the failure mechanism of WSPC.All authors gratefully acknowledge the support of the project TSSiPRO-NORTE-01-0145-FEDER-000015 funded by the regional operational program NORTE 2020, under the PORTUGAL 2020 Partnership Agreement, through the European Regional Development Fund. The partial support by FEDER funds through the COMPETE program and by national funds through FCT – Foundation for Science and Technology (Portugal) within the project POCI-01-0145-FEDER007136 is also acknowledged. SDT acknowledges FCT for the financial support through the project SFRH/BD/94759/2013. Moreover, the first author thanks for the financial support of the European Regional Development Fund ERDF, through the operational program for COMPETE 2020 and by FCT within the project PTDC/EMEEME/30967/2017 and NORTE-0145-FEDER-030967. Additionally, N. Dencheva is also grateful for the financial support of FCT in the frames of the strategic project UID/CTM/50025/2013 and the personal program contract CTTI-51/18-IPC

A Reproducible Approach to the Assembly of Microcapillaries for Double Emulsion Production

Double emulsions attract considerable interest for their potential utility in applications as diverse as drug delivery, contrast agents, and compartmentalizing analytes for fluorescence-activated cell sorting (FACS). Microfluidic platforms provide a particularly elegant approach to generating these structures, but the construction of devices to provide reproducible and stable production of double emulsions remains challenging. PDMS-based systems require specialized surface treatments that are difficult to implement and lack long-term stability, and current glass microcapillary systems, while offering some advantages, lack flexible and reproducible methods for capillary alignment. This article describes a microcapillary-based approach that addresses these key challenges. Our approach utilizes translational stage elements and alignment end caps that are fixed in place once configured, rather than tightly fitting capillaries. This new approach enables alignment to within ± 10 µm and allows greater flexibility in choosing the dimensions of the capillary, which contributes to the size and stability of formation of the double emulsion. Importantly, it also allows the user to compensate for the deviations from ideal shape that occur in pulled glass capillaries, which has been a source of failure with previous methods. A detailed description of the critical design and operational parameters that affect double emulsion generation in these capillary microfluidic devices is provided

Redshift-weighted constraints on primordial non-Gaussianity from the clustering of the eBOSS DR14 quasars in Fourier space

We present constraints on local primordial non-Gaussianity (PNG), parametrized through $f^{\rm loc}_{\rm NL}$, using the Sloan Digital Sky Survey IV extended Baryon Oscillation Spectroscopic Survey Data Release 14 quasar sample. We measure and analyze the anisotropic clustering of the quasars in Fourier space, testing for the scale-dependent bias introduced by primordial non-Gaussianity on large scales. We derive and employ a power spectrum estimator using optimal weights that account for the redshift evolution of the PNG signal. We find constraints of $-51<f^{\rm loc}_{\rm NL}<21$ at 95% confidence level. These are amont the tightest constraints from Large Scale Structure (LSS) data. Our redshift weighting improves the error bar by 15% in comparison to the unweighted case. If quasars have lower response to PNG, the constraint degrades to $-81<f^{\rm loc}_{\rm NL}<26$, with a 40% improvement over the standard approach. We forecast that the full eBOSS dataset could reach $\sigma_{f^{\rm loc}_{\rm NL}}\simeq 5\text{-}8$ using optimal methods and full range of scales.Comment: 28 pages, 12 figures. Comments welcome

f(R)f(R) Gravity and Crossing the Phantom Divide Barrier

The $f(R)$ gravity models formulated in Einstein conformal frame are equivalent to Einstein gravity together with a minimally coupled scalar field. We shall explore phantom behavior of $f(R)$ models in this frame and compare the results with those of the usual notion of phantom scalar field.Comment: 13 Pages, 9 figures. To appear in Physics Letters