Filling the void in confined polymer nematics: phase transitions in a minimal model of dsDNA packing

Inspired to understand the complex spectrum of space-filling organizations the dsDNA genome within the capsid of bacterial viruses, we study a minimal, coarse-grained model of single chains densely-packed into a finite spherical volume. We build the three basic elements of the model--i) the absence of chain ends ii) the tendency of parallel-strand alignment and iii) a preference of uniform areal density of chain segments--into a polymer nematic theory for confined chains. Given the geometric constraints of the problem, we show that axially symmetric packings fall into one of three topologies: the coaxial spool; the simple solenoid; and the twisted-solenoid. Among these, only the twisted-solenoid fills the volume without the presence of line-like disclinations, or voids, and are therefore generically preferred in the incompressible limit. An analysis of the thermodynamics behavior of this simple model reveals a rich behavior, a generic sequence of phases from the empty state for small container sizes, to the coaxial spool configuration at intermediate sizes, ultimately giving way, via a second-order, symmetry-breaking transition, to the twisted-solenoid structure above a critical sphere size.Comment: 7 pages; 3 figure

The Milky Way Galaxy as a Strong Gravitational Lens

We study the gravitational lensing effects of spiral galaxies by taking a model of the Milky Way and computing its lensing properties. The model is composed of a spherical Hernquist bulge, a Miyamoto-Nagai disc and an isothermal halo. As a strong lens, a spiral galaxy like the Milky Way can give rise to four different imaging geometries. They are (i) three images on one side of the galaxy centre (`disc triplets'), (ii) three images with one close to the centre (`core triplets'), (iii) five images and (iv) seven images. Neglecting magnification bias, we show that the core triplets, disc triplets and fivefold imaging are roughly equally likely. Even though our models contain edge-on discs, their image multiplicities are not dominated by disc triplets. The halo has a small effect on the caustic structure, the time delays and brightnesses of the images. The Milky Way model has a maximum disc (i.e., the halo is not dynamically important in the inner parts). Strong lensing by nearly edge-on disc galaxies breaks the degeneracy between the relative contribution of the disc and halo to the overall rotation curve. If a spiral galaxy has a sub-maximum disc, then the astroid caustic shrinks dramatically in size, whilst the radial caustic shrinks more modestly. This causes changes in the relative likelihood of the image geometries, specifically (i) core triplets are now 9/2 times more likely than disc triplets, (ii) the cross section for threefold imaging is reduced by a factor of 2/3, whilst (iii) the cross section for fivefold imaging is reduced by 1/2. Although multiple imaging is less likely (the cross sections are smaller), the average total magnification is greater.Comment: MNRAS, in pres

Thermal And Mechanical Analysis of High-power Light-emitting Diodes with Ceramic Packages

In this paper we present the thermal and mechanical analysis of high-power light-emitting diodes (LEDs) with ceramic packages. Transient thermal measurements and thermo-mechanical simulation were performed to study the thermal and mechanical characteristics of ceramic packages. Thermal resistance from the junction to the ambient was decreased from 76.1 oC/W to 45.3 oC/W by replacing plastic mould to ceramic mould for LED packages. Higher level of thermo-mechanical stresses in the chip were found for LEDs with ceramic packages despite of less mismatching coefficients of thermal expansion comparing with plastic packages. The results suggest that the thermal performance of LEDs can be improved by using ceramic packages, but the mounting process of the high power LEDs with ceramic packages is critically important and should be in charge of delaminating interface layers in the packages.Comment: Submitted on behalf of TIMA Editions (http://irevues.inist.fr/tima-editions

Development of Streams Classification System for Nutrient Criteria in Illinois

USEPApublished or submitted for publicationis peer reviewe

Queueing analysis of a canonical model of real-time multiprocessors

A logical classification of multiprocessor structures from the point of view of control applications is presented. A computation of the response time distribution for a canonical model of a real time multiprocessor is presented. The multiprocessor is approximated by a blocking model. Two separate models are derived: one created from the system's point of view, and the other from the point of view of an incoming task

Technical note: Absorption aerosol optical depth components from AERONET observations of mixed dust plumes

© Author(s) 2019.Absorption aerosol optical depth (AAOD) as obtained from sun–sky photometer measurements provides a measure of the light-absorbing properties of the columnar aerosol loading. However, it is not an unambiguous aerosol-type-specific parameter, particularly if several types of absorbing aerosols, for instance black carbon (BC) and mineral dust, are present in a mixed aerosol plume. The contribution of mineral dust to total aerosol light absorption is particularly important at UV wavelengths. In this study we refine a lidar-based technique applied to the separation of dust and non-dust aerosol types for the use with Aerosol Robotic Network (AERONET) direct sun and inversion products. We extend the methodology to retrieve AAOD related to non-dust aerosol (AAODnd) and BC (AAODBC). We test the method at selected AERONET sites that are frequently affected by aerosol plumes that contain a mixture of Saharan or Asian mineral dust and biomass-burning smoke or anthropogenic pollution, respectively. We find that aerosol optical depth (AOD) related to mineral dust as obtained with our methodology is frequently smaller than coarse-mode AOD. This suggests that the latter is not an ideal proxy for estimating the contribution of mineral dust to mixed dust plumes. We present the results of the AAODBC retrieval for the selected AERONET sites and compare them to coincident values provided in the Copernicus Atmosphere Monitoring System aerosol reanalysis.We find that modelled and AERONET AAODBC are most consistent for Asian sites or at Saharan sites with strong local anthropogenic sources.Peer reviewe

Feedback effects on the current correlations in Y-shaped conductors

We study current fluctuations in a Y-shaped conductor connected to external leads with finite impedances. We show that, due to voltage fluctuations in the circuit, the moments of the transferred charges cannot be obtained from simple rescaling of the bare values already in the second moments. The cross-correlation between the output terminals can change from negative to positive under certain parameter regimes.Comment: 4 pages, figures attached separatel