Propagation of Rarefaction Pulses in Discrete Materials with Strain-Softening Behavior

Discrete materials composed of masses connected by strongly nonlinear links with anomalous behavior (reduction of elastic modulus with strain) have very interesting wave dynamics. Such links may be composed of materials exhibiting repeatable softening behavior under loading and unloading. These discrete materials will not support strongly nonlinear compression pulses due to nonlinear dispersion but may support stationary rarefaction pulses or rarefaction shock-like waves. Here we investigate rarefaction waves in nonlinear periodic systems with a general power-law relationship between force and displacement $F \propto \delta^{n}$, where $0 < n < 1$. An exact solution of the long-wave approximation is found for the special case of $n = 1/2$, which agrees well with numerical results for the discrete chain. Theoretical and numerical analysis of stationary solutions are discussed for different values of $n$ in the interval $0 < n < 1$. The leading solitary rarefaction wave followed by a dispersive tail was generated by impact in numerical calculations.Comment: 15 pages, 4 figure

A method validation for simultaneous determination of phthalates and bisphenol A released from plastic water containers

Phthalates (or phthalate esters, PAEs) and bisphenol A (BPA) are widely used in various industries, particularly in the fields of cosmetics and packaging, and they increase the malleability and workability of materials. As a result of their use, some international health organizations have begun to study them. In this study, the authors developed a methodology for the simultaneous determination of dimethyl phthalate (DMP), diethyl phthalate (DEP), diisobutyl phthalate (DiBP); dibutyl phthalate (DBP), bis(2-ethylhexyl) phthalate (DEHP); di-n-octyl-phthalate (DnOP) and bisphenol A (BPA) from drinking and non-potable waters. The extraction of PAEs and BPA was performed using a solvent-based dispersive liquid-liquid microextraction (SB-DLLME) method. The analytical determination was performed using a gas chromatography-ion trap mass spectrometry (GC-IT/MS) analysis. The entire procedure was validated as recoveries were studied according to the volume and the extraction solvent used, pH, and ionic strength. Dynamic linearity ranges and linear equations of all the compounds were experimentally determined as well as the limit of detection (LOD) (1-8 ng mL-1) and the limit of quantification (LOQ) (5-14 ng mL-1), reproducibility, and sensitivity. The method was applied to 15 water samples (mineral water and tap water) for determining PAEs and BPA released from the plastic container. After the release simulation, four PAEs (i.e., DiBP, DBP, DHEP, and DnOP) were determined at very low concentrations (below 1.2 ng mL-1) in two water samples from (sport) bottles

Increasing future gravitational-wave detectors sensitivity by means of amplitude filter cavities and quantum entanglement

The future laser interferometric gravitational-wave detectors sensitivity can be improved using squeezed light. In particular, recently a scheme which uses the optical field with frequency dependent squeeze factor, prepared by means of a relatively short (~30 m) amplitude filter cavity, was proposed \cite{Corbitt2004-3}. Here we consider an improved version of this scheme, which allows to further reduce the quantum noise by exploiting the quantum entanglement between the optical fields at the filter cavity two ports.Comment: 10 pages, 7 figure

A survey on energy efficiency in information systems

Concerns about energy and sustainability are growing everyday involving a wide range of fields. Even Information Systems (ISs) are being influenced by the issue of reducing pollution and energy consumption and new fields are rising dealing with this topic. One of these fields is Green Information Technology (IT), which deals with energy efficiency with a focus on IT. Researchers have faced this problem according to several points of view. The purpose of this paper is to understand the trends and the future development of Green IT by analyzing the state-of-the-art and classifying existing approaches to understand which are the components that have an impact on energy efficiency in ISs and how this impact can be reduced. At first, we explore some guidelines that can help to understand the efficiency level of an organization and of an IS. Then, we discuss measurement and estimation of energy efficiency and identify which are the components that mainly contribute to energy waste and how it is possible to improve energy efficiency, both at the hardware and at the software level

Who brings home the bacon? The influence of context on partners&apos; contributions to the household income

Background: Female-breadwinner families represent a relatively new phenomenon in Europe. Little is known about the determinants of this couple type, which sensibly diverts from the traditional economic superiority of men within the household.Objective: This paper studies the contextual correlates of partners’ contribution to the household income, distinguishing between female-breadwinner, male-breadwinner, and equal-income couples. In particular, it focuses on the role of male unemployment rate and the prevalence of gender-egalitarian attitudes as possible explanations for the emergence of female-breadwinner and equal-income couples across European regions and countries.Methods: Using data from the fifth round (2010/2011) of the European Social Survey, integrated with data from the Eurostat database, we model the categorical variable identifying the couple type (male-breadwinner, female-breadwinner, or equal-income couple) by using a multilevel multinomial logistic regression model where individuals are nested within regions and countries.Results: The prevalence of female-breadwinner, male-breadwinner, and equal-income couples varies considerably across European countries as well as within countries. The prevalence of female-breadwinner couples is positively associated with male unemployment, while it is not influenced by the diffusion of gender-egalitarian attitudes. However, the diffusion of gender-egalitarian attitudes matters for explaining the variation in the prevalence of equal-income couples across Europe.Contribution: We add to the literature on partners’ contributions to household income by analysing the spatial distribution and the contextual correlates of female-breadwinner, male-breadwinner, and equal-income couples across European countries and regions.<br/

Self-cooling of a movable mirror to the ground state using radiation pressure

We show that one can cool a micro-mechanical oscillator to its quantum ground state using radiation pressure in an appropriately detuned cavity (self-cooling). From a simple theory based on Heisenberg-Langevin equations we find that optimal self-cooling occurs in the good cavity regime, when the cavity bandwidth is smaller than the mechanical frequency, but still larger than the effective mechanical damping. In this case the intracavity field and the vibrational mechanical mode coherently exchange their fluctuations. We also present dynamical calculations which show how to access the mirror final temperature from the fluctuations of the field reflected by the cavity.Comment: 4 pages, 3 figure

Quantum-limited force measurement with an optomechanical device

We study the detection of weak coherent forces by means of an optomechanical device formed by a highly reflecting isolated mirror shined by an intense and highly monochromatic laser field. Radiation pressure excites a vibrational mode of the mirror, inducing sidebands of the incident field, which are then measured by heterodyne detection. We determine the sensitivity of such a scheme and show that the use of an entangled input state of the two sideband modes improves the detection, even in the presence of damping and noise acting on the mechanical mode.Comment: 8 pages, 4 figure

Comment on: Evidence and Stability Field of fcc Superionic Water Ice Using Static Compression

Weck et al. (1) report on the existence and stability fields of two superionic (SI) phases of H2O ice at high P-T (P-T) conditions, which has been a topic of static and dynamic experiments and theoretical calculations (see Ref. (2) and references therein). They confirm Ref. (2) in that there are two SI phases with bcc and fcc oxygen sublattices with the stability at low- and high-P. However, they report on an extended stability field of fcc-SI ice toward lower T but no sign of it below 57 GPa. Here we argue that the reported phase boundaries of fcc-SI phase are not well experimentally justified due to difficulties to perform adequate X-ray diffraction (XRD) and radiometric measurements.Comment: 2 pages, 2 figures, 2 reference

Computer vision approach for the determination of microbial concentration and growth kinetics using a low cost sensor system

The measurement of microbial contamination is of primary importance in different fields, from environmental monitoring to food safety and clinical analysis. Today, almost all microbiology laboratories make microbial concentration measurements using the standard Plate Count Technique (PCT), a manual method that must be performed by trained personnel. Since manual PCT analysis can result in eye fatigue and errors, in particular when hundreds of samples are processed every day, automatic colony counters have been built and are commercially available. While quick and reliable, these instruments are generally expensive, thus, portable colony counters based on smartphones have been developed and are of low cost but also not accurate as the commercial benchtop instruments. In this paper, a novel computer vision sensor system is presented that can measure the microbial concentration of a sample under test and also estimate the microbial growth kinetics by monitoring the colonies grown on a Petri dish at regular time intervals. The proposed method has been in-house validated by performing PCT analysis in parallel under the same conditions and using these results as a reference. All the measurements have been carried out in a laboratory using benchtop instruments, however, such a system can also be realized as an embedded sensor system to be deployed for microbial analysis outside a laboratory environment

High-Pressure Synthesis of a Pentazolate Salt

The pentazolates, the last all-nitrogen members of the azole series, have been notoriously elusive for the last hundred years despite enormous efforts to make these compounds in either gas or condensed phases. Here we report a successful synthesis of a solid state compound consisting of isolated pentazolate anions N5-, which is achieved by compressing and laser heating cesium azide (CsN3) mixed with N2 cryogenic liquid in a diamond anvil cell. The experiment was guided by theory, which predicted the transformation of the mixture at high pressures to a new compound, cesium pentazolate salt (CsN5). Electron transfer from Cs atoms to N5 rings enables both aromaticity in the pentazolates as well as ionic bonding in the CsN5 crystal. This work provides a critical insight into the role of extreme conditions in exploring unusual bonding routes that ultimately lead to the formation of novel high nitrogen content species