Time-resolved dynamics of granular matter by random laser emission

Because of the huge commercial importance of granular systems, the second-most used material in industry after water, intersecting the industry in multiple trades, like pharmacy and agriculture, fundamental research on grain-like materials has received an increasing amount of attention in the last decades. In photonics, the applications of granular materials have been only marginally investigated. We report the first phase-diagram of a granular as obtained by laser emission. The dynamics of vertically-oscillated granular in a liquid solution in a three-dimensional container is investigated by employing its random laser emission. The granular motion is function of the frequency and amplitude of the mechanical solicitation, we show how the laser emission allows to distinguish two phases in the granular and analyze its spectral distribution. This constitutes a fundamental step in the field of granulars and gives a clear evidence of the possible control on light-matter interaction achievable in grain-like system.Comment: 16 pages, 7 figure

Gender Differences in Dispute Resolution Practice: Report on the ABA Section of Dispute Resolution Practice Snapshot Survey

Some of the goals of the WIDR Committee were to change how neutral selection occurs in disputes, to increase the number of women who serve as neutrals, and to ensure that women and minorities were proportionally represented as neutrals.9 The first step, before suggesting changes, was to understand the current situation in the world of dispute resolution. In fall 2012, the Section of Dispute Resolution surveyed the lawyers belonging to the Section to determine how mediators and arbitrators are selected in legal cases and the types of cases being resolved through the many available dispute resolution processes. Specifically, the survey was designed to examine who is being selected as a neutral, by whom, using what process, and for what types of cases. This report explains the methodology of the survey, the demographics of the respondents and neutrals involved in particular cases, and, most importantly, the information about neutral selection

Shaken Granular Lasers

Granular materials have been studied for decades, also driven by industrial and technological applications. These very simple systems, composed by agglomerations of mesoscopic particles, are characterized, in specific regimes, by a large number of metastable states and an extreme sensitivity (e.g., in sound transmission) on the arrangement of grains; they are not substantially affected by thermal phenomena, but can be controlled by mechanical solicitations. Laser emission from shaken granular matter is so far unexplored; here we provide experimental evidence that it can be affected and controlled by the status of motion of the granular, we also find that competitive random lasers can be observed. We hence demonstrate the potentialities of gravity affected moving disordered materials for optical applications, and open the road to a variety of novel interdisciplinary investigations, involving modern statistical mechanics and disordered photonics.Comment: 4 pages, 3 figures. To be published in Physical Review Letter

Quiescent low-mass galaxies observed by JWST in the Epoch of Reionization

The surprising JWST discovery of a quiescent, low-mass ($M_\star=10^{8.7} \rm M_\odot$) galaxy at redshift $z=7.3$ (JADES-GS-z7-01-QU) represents a unique opportunity to study the imprint of feedback processes on early galaxy evolution. We build a sample of 130 low-mass ($M_\star\lesssim 10^{9.5} \rm M_\odot$) galaxies from the SERRA cosmological zoom-in simulations, which show a feedback-regulated, bursty star formation history (SFH). The fraction of time spent in an active phase increases with the stellar mass from $f_{duty}\approx 0.6$ at $M_\star\approx 10^{7.5} \rm M_\odot$ to $\approx 0.99$ at $M_\star\geq 10^{9} \rm M_\odot$, and it is in agreement with the value $f_{duty}\approx 0.75$ estimated for JADES-GS-z7-01-QU. On average, 30% of the galaxies are quiescent in the range $6 < z < 8.4$; they become the dominant population at $M_\star\lesssim 10^{8.3} \rm M_\odot$. However, none of these quiescent systems matches the Spectral Energy Distribution of JADES-GS-z7-01-QU, unless their SFH is artificially truncated a few Myr after the main star formation peak. As supernova feedback can only act on a longer timescale ($\gtrsim 30 \rm \, Myr$), this implies that the observed abrupt quenching must be caused by a faster physical mechanism, such as radiation-driven winds.Comment: submitted to ApJ Letters, 5 pages, 4 figure

Dwarf satellites of high-z Lyman Break Galaxies: a free lunch for JWST

We show that the James Webb Space Telescope will be able to detect dwarf satellites of high-$z$ Lyman Break Galaxies (LBGs). To this aim, we use cosmological simulations following the evolution of a typical $M_\star\simeq10^{10}\rm M_\odot$ LBG up to $z\simeq6$, and analyse the observational properties of its five satellite dwarf galaxies ($10^7{\rm M_\odot}<M_\star<10^9{\rm M_\odot}$). Modelling their stellar emission and dust attenuation, we reconstruct their rest-frame UV-optical spectra for $6<z<6.5$. JWST/NIRCam synthetic images show that the satellites can be spatially resolved from their host, and their emission is detectable by planned deep surveys. Moreover, we build synthetic spectral energy distributions and colour-magnitude diagrams for the satellites. We conclude that the color $\rm F200W-F356W$ is a powerful diagnostic tool for understanding their physical properties once they have been identified. For example, $\rm F200W-F356W~\lesssim-0.25$ can be used to identify star-bursting ($\rm SFR\sim5~M_\odot yr^{-1}$), low-mass ($M_\star\lesssim5\times 10^8\rm M_\odot$) systems, with $\sim80\%$ of their stars being young and metal-poor ($\log(Z_\star/Z_\odot) < -0.5$).Comment: 8 pages, 3 figures, accepted for publication in ApJ

University students' discourse about irreducible polynomials

The purpose of this paper is to analyse, following Sfard’s theoretical framework, the students’ discourse about irreducible polynomials in order to understand their difficulties. Through the students’ explanations, given during the interviews conducted after carrying out the questionnaire, it is possible to study which processes were triggered by them to solve the task. In particular, we focused on the concept of the irreducible polynomials and the link between the roots of the polynomial and its reducibility in university students

Microbial status and quality of rabbit meat after rabbits feed supplementation with phyto-additives

Nowdays, there is an increasing  interest in public health issue due to consumption of healthy and nutritive food, e.i. rich in proteins, low in cholesterol and lipid contents. The aim of this study was to examine if oregano, sage and Eleutherococcus senticosus extracts, commercial Xtract as well can influence microbial status of rabbit meat after their supplementation of rabbit feed. Reduction of enterococci, coagulase-negative staphylococci and Staphylococcus aureus after feed supplementation by the sage and oregano was more detectable at the end of the experiment (at day 42) than after their application (at day 21). In animals with Xtract addition, antibacterial effect has been noted already at day 21. Our in vivo results confirmed in vitro antibacterial effect of the tested extracts and showed that maintaining of rabbit meat quality by plant extracts is very promising

Using Business Intelligence Tools to Support Medical Validation of Laboratory Tests

Modern clinical laboratories have to confirm that the procedures used for specific tests are reliable and valid. There are several sources of errors and interferences that can invalidate the results. Medical validation refers to the plausibility check of the test results. Implausible results indicate that something might went wrong with a sample retrieved from the patient, e.g., the blood sample got contaminated with another fluid, which requires re-examination. Here, we describe how an integrated R-based business intelligence (BI) tool can be developed that increase the efficiency of the medical validation at the Institute of Clinical Chemistry (ICC) of the University Hospital Zurich. A BI software environment allowed us to digitalize steps in the validation process that were manually done in Excel worksheets, e.g., importing the data, calculating percentiles, and producing graphical outputs