Response to “Comment on ‘Elasticity of flexible and semiflexible polymers with extensible bonds in the Gibbs and Helmholtz ensembles”’ [J. Chem. Phys. 138, 157101 (2013)]

No abstract: this is a "response" to a Comment

Monte Carlo simulations of single polymer force-extension relations

We present Monte Carlo simulations for studying the statistical mechanics of arbitrarily long single molecules under stretching. In many cases in which the thermodynamic limit is not satisfied, different statistical ensembles yield different macroscopic force-displacement curves. In this work we provide a description of the Monte Carlo simulations and discuss in details the assumptions adopted

RoboJam: A Musical Mixture Density Network for Collaborative Touchscreen Interaction

RoboJam is a machine-learning system for generating music that assists users of a touchscreen music app by performing responses to their short improvisations. This system uses a recurrent artificial neural network to generate sequences of touchscreen interactions and absolute timings, rather than high-level musical notes. To accomplish this, RoboJam's network uses a mixture density layer to predict appropriate touch interaction locations in space and time. In this paper, we describe the design and implementation of RoboJam's network and how it has been integrated into a touchscreen music app. A preliminary evaluation analyses the system in terms of training, musical generation and user interaction

Understanding the determinants of stability and folding of small globular proteins from their energetics

The results of minimal model calculations suggest that the stability and the kinetic accessibility of the native state of small globular proteins are controlled by few "hot" sites. By mean of molecular dynamics simulations around the native conformation, which simulate the protein and the surrounding solvent at full--atom level, we generate an energetic map of the equilibrium state of the protein and simplify it with an Eigenvalue decomposition. The components of the Eigenvector associated with the lowest Eigenvalue indicate which are the "hot" sites responsible for the stability and for the fast folding of the protein. Comparison of these predictions with the results of mutatgenesis experiments, performed for five small proteins, provide an excellent agreement

Comparative Assessment Of Different Constellation Geometries For Space-Based Application

As services from space are becoming an asset for life on Earth and the demand for data from space increases, the international interest in satellite constellations is increasingly growing. GPS (Global Positioning System) provides positioning and navigation. Iridium contains a relatively larger number of satellites for communication purpose. Molniya is a high elliptical orbits constellation providing high latitude coverage. Disaster Monitoring constellation consists of remote sensing satellites and brings responsiveness needed for emergencies. Recently, some companies, such as OneWeb, Samsung and Space-X, have made public their plan to deploy mega constellations of nanosatellites for global internet. Different constellation geometries have been proposed to meet various mission requirements, each one having specific advantages in terms of coverage, responsiveness, cost, etc. Thus, designing a constellation is a trade-off choice. The choice for a constellation is highly influenced by many factors, such as the system cost, the interaction with space environment (radiation and space debris), and the targeted terrestrial coverage. The design of a constellation requires selecting the parameters that best meet the mission requirements. To accomplish this, several studies on the comparison of satellite constellations proposed detailed analysis, e.g. the multi-criteria comparison for responsive constellations, the coverage assessment of elliptical constellations. However, most of them only focused on one or few performances, lacking of generalisation. A general study of constellation geometry can provide a basis for understanding the constellation design. This will allow the process of constellation design to be expedited by offering a proposal of an existing constellation style. This paper comparatively assesses different constellation geometries, including the classical proposed geometries and some less used configurations, and chooses the constellation geometry best suitable for a given mission (e.g. remote sensing, global internet). In this work, several parameters of constellation design will be considered to make a quantitative assessment: coverage (global or local), frequency of ground track repetition, responsiveness (i.e., how fast a satellite can be launched and the data return to Earth after launch), robustness to failure and speed of replenishment, end of life disposal, number of satellites and orbital altitude. The assessment will be conducted in a parametric approach. Each factor will be quantitatively evaluated by deriving a fitness function. Then, a series of weighting coefficients adapted to the given mission requirements will be chosen for the global fitness functions. Through multi objective optimisation, the constellation geometry best suitable for the given mission requirements will be derived

Digital Artefacts and The Role of Digital Affordance

This work investigates how the concept of affordance should be revised following the digital evolution. Starting from a review of the literature about affordance, the most acknowledged constructs are compared with the variegated definitions of digital artefacts. The paper proposes a definition of digital affordance, overcoming the inconsistencies identified in the literature. The study is enriched by a series of interviews to investigate the final users' perception of affordance. Finally, the paper shows the application of the proposed model with a case study related to food delivery services

Optical Spectroscopy of X-Mega targets in the Carina Nebula - VI. FO 15: a new O-Type double-lined eclipsing binary

We report the discovery of a new O-type double-lined spectroscopic binary with a short orbital period of 1.4 days. We find the primary component of this binary, FO 15, to have an approximate spectral type O5.5Vz, i.e. a Zero-Age-Main-Sequence star. The secondary appears to be of spectral type O9.5V. We have performed a numerical model fit to the public ASAS photometry, which shows that FO 15 is also an eclipsing binary. We find an orbital inclination of ~ 80 deg. From a simultaneous light-curve and radial velocity solution we find the masses and radii of the two components to be 30 +/- 1 and 16 +/- 1 solar masses and 7.5 +/- 0.5 and 5.3 +/- 0.5 solar radii. These radii, and hence also the luminosities, are smaller than those of normal O-type stars, but similar to recently born ZAMS O-type stars. The absolute magnitudes derived from our analysis locate FO 15 at the same distance as Eta Carinae. From Chandra and XMM X-ray images we also find that there are two close X-ray sources, one coincident with FO 15 and another one without optical counterpart. This latter seems to be a highly variable source, presumably due to a pre-main-sequence stellar neighbour of FO 15.Comment: 11 pages, 9 figures, 3 tables. Accepted for publication in MNRAS. Higher resolution version available at http://lilen.fcaglp.unlp.edu.ar/papers2006.htm

Theory and Monte Carlo simulations for the stretching of flexible and semiflexible single polymer chains under external fields

Stretching experiments on single molecules of arbitrary length opened the way for studying the statistical mechanics of small systems. In many cases in which the thermodynamic limit is not satisfied, different macroscopic boundary conditions, corresponding to different statistical mechanics ensembles, yield different force-displacement curves. We formulate analytical expressions and develop Monte Carlo simulations to quantitatively evaluate the difference between the Helmholtz and the Gibbs ensembles for a wide range of polymer models of biological relevance. We consider generalizations of the freely jointed chain and of the worm-like chain models with extensible bonds. In all cases we show that the convergence to the thermodynamic limit upon increasing contour length is described by a suitable power law and a specific scaling exponent, characteristic of each model. (C) 2012 American Institute of Physics

Virome-associated antibiotic-resistance genes in an experimental aquaculture facility

We report the comprehensive characterization of viral and microbial communities within an aquaculture wastewater sample, by a shotgun sequencing and 16S rRNA gene profiling metagenomic approach. Caudovirales had the largest representation within the sample, with over 50% of the total taxonomic abundance, whereas approximately 30% of the total open reading frames (ORFs) identified were from eukaryotic viruses (Mimiviridae and Phycodnaviridae). Antibiotic resistance genes (ARGs) within the virome accounted for 0.85% of the total viral ORFs and showed a similar distribution both in virome and in microbiome. Among the ARGs, those encoding proteins involved in the modulation of antibiotic efflux pumps were the most abundant. Interestingly, the taxonomy of the bacterial ORFs identified in the viral metagenome did not reflect the microbial taxonomy as deduced by 16S rRNA gene profiling and shotgun metagenomic analysis. A limited number of ARGs appeared to be mobilized from bacteria to phages or vice versa, together with other bacterial genes encoding products involved in general metabolic functions, even in the absence of any antibiotic treatment within the aquaculture plant. Thus, these results confirm the presence of a complex phage-bacterial network in the aquaculture environment