Comparing cavity and ordinary laser cooling within the Lamb-Dicke regime

Cavity-mediated cooling has the potential to become one of the most efficient techniques to cool molecular species down to very low temperatures. In this paper we analyse cavity cooling with single-laser driving for relatively large cavity decay rates kappa and relatively large phonon frequencies nu. It is shown that cavity cooling and ordinary laser cooling are essentially the same within the validity range of the Lamb-Dicke approximation. This is done by deriving a closed set of rate equations and calculating the corresponding stationary state phonon number and cooling rate. For example, when nu is either much larger or much smaller than kappa, the minimum stationary state phonon number scales as kappa^2/16 nu^2 (strong confinement regime) and as kappa / 4 nu (weak confinement regime), respectively.Comment: 12 pages, 8 figures, final version accepted for publicatio

A rate equation approach to cavity mediated laser cooling

The cooling rate for cavity mediated laser cooling scales as the Lamb-Dicke parameter eta squared. A proper analysis of the cooling process hence needs to take terms up to eta^2 in the system dynamics into account. In this paper, we present such an analysis for a standard scenario of cavity mediated laser cooling with eta << 1. Our results confirm that there are many similarities between ordinary and cavity mediated laser cooling. However, for a weakly confined particle inside a strongly coupled cavity, which is the most interesting case for the cooling of molecules, numerical results indicate that even more detailed calculations are needed to model the cooling process accurately.Comment: 15 pages, 10 figures, minor corrections, PRA (in press

Applying the Submerged Jet Erosion Test to Embankment Dam Breach Modeling

The submerged jet erosion test (JET) is one of several methods available for quantifying erodibility of cohesive soils, a crucial input for modeling erosion and breach of embankment dams with models such as WinDAM, EMBREA (Morris 2011), and DL BREACH (Wu 2013; 2016a; 2016b). The JET was initially developed in the late 1980s as a relatively large-scale device with a 13-mm diameter nozzle creating an impinging jet that erodes a soil sample submerged in a 61-cm diameter tank. This first device was documented in an ASTM standard (D5852-1995), but the standard was withdrawn in 2016. In the last 15 to 20 years, smaller scale devices have become common, including one described as the “original JET” (6.4-mm nozzle operating within a 30.5-cm tank) (Hanson and Cook 2004) and the newer “mini-JET” (3 mm nozzle and 10-cm tank) (Al-Madhhachi et al. 2013b). New methods for analyzing the scour-vs.-time data obtained from the JET have also been proposed, some (Daly et al. 2013) based on the traditional linear excess stress equation describing the soil etachment process, and others (Al-Madhhachi et al. 2013a) based on nonlinear soil erosion models such as the mechanistic Wilson model (Wilson 1993a, 1993b). This paper provides an overview of JET history and development and then summarizes a recent study (Wahl 2021) comparing JET data analysis methods. Fifty-two JET experiments on four different soil types (lean clay, silty clay, clayey sand, and silty sand) were analyzed by nine different methods. The results give indications of the practical value of linear vs. nonlinear soil erosion models and the effectiveness of different curve-fitting methods for estimating erodibility parameters. Suggestions for the use of the JET in dam breach modeling are offered

Strongly Coupled Electron–Phonon Dynamics in Few-Layer TiSe_2 Exfoliates

Ultrafast electron diffraction is used to probe the time-resolved dynamics in a few-layer TiSe_2 sample. At normal incidence, the suppression of the Bragg diffraction peak intensities following photoexcitation displays strongly biexponential behavior. For tilted samples, changes in the diffraction peak positions reveal coherent acoustic vibrations that are dependent on the sample thickness and that further permit a calculation of the Young’s modulus. The complex room temperature lattice dynamics observed are attributed to strong electron–phonon coupling and electron–lattice equilibration processes, which support a Jahn–Teller origin of the charge density wave behavior in TiSe_2. Additionally, the significant role that the related Kohn anomalies may play in the electron transport dynamics and transition mechanism of this material is emphasized. These results demonstrate the importance of strongly coupled electron–phonon dynamics in the relaxation of electronically excited room temperature TiSe2, which is expected to impact its applicability in optoelectronics

Separation and Characterization of Respirable Amphibole Fibers from Libby, Montana

The vermiculite mine in Libby, Montana, was in operation for over 70 yr and was contaminated with asbestos-like amphibole fibers. The mining, processing, and shipping of this vermiculite led to significant fiber inhalation exposure throughout the community, and residents of Libby have developed numerous pulmonary diseases such as lung cancer and mesothelioma. The present study describes the separation of Libby 6-mix into respirable and nonrespirable size fractions by means of aqueous elutriation. The elutriator, designed to separate fibers with aerodynamic diameters smaller than 2.5 μm (respirable) from larger fibers, used an upward flow rate of 3.4 × 10−4 cm s−1. The resultant respirable fraction constituted only 13% of the raw Libby 6-mix mass, and less than 2% of the fibers in the elutriated fraction had aerodynamic diameters exceeding 2.5 μm. Surface area of the elutriated fibers was 5.3 m−2 g−1, compared to 0.53 m−2 g−1 for the raw fibers. There were no detectable differences in chemical composition between the larger and smaller fibers. Such harvesting of respirable fractions will allow toxicological studies to be conducted within a controlled laboratory setting, utilizing fiber sizes that may more accurately simulate historical exposure of Libby residents’ lungs. Importantly, this work describes a method that allows the use of material enriched in more uniform respirable material than raw Libby 6-mix, making comparisons with other known fiber preparations more valid on a mass basis

Strongly Coupled Electron–Phonon Dynamics in Few-Layer TiSe_2 Exfoliates

Ultrafast electron diffraction is used to probe the time-resolved dynamics in a few-layer TiSe_2 sample. At normal incidence, the suppression of the Bragg diffraction peak intensities following photoexcitation displays strongly biexponential behavior. For tilted samples, changes in the diffraction peak positions reveal coherent acoustic vibrations that are dependent on the sample thickness and that further permit a calculation of the Young’s modulus. The complex room temperature lattice dynamics observed are attributed to strong electron–phonon coupling and electron–lattice equilibration processes, which support a Jahn–Teller origin of the charge density wave behavior in TiSe_2. Additionally, the significant role that the related Kohn anomalies may play in the electron transport dynamics and transition mechanism of this material is emphasized. These results demonstrate the importance of strongly coupled electron–phonon dynamics in the relaxation of electronically excited room temperature TiSe2, which is expected to impact its applicability in optoelectronics

More than a Drop in the Bucket: The Social and Economic Costs of Dropouts and Grade Retentions Associated With Exclusionary Discipline

Each year many students are subject to exclusionary discipline, in fact, 60% of students in Texas are disciplined at-least once between grades 7 through 12. The purpose of this study is to examine the impact of school discipline contact on students’ risk for grade retention and school dropout using a statewide sample of nearly one million 7th grade students tracked through their 12th grade year. Results indicate that school discipline relates to a 24% increase in high school dropout. These additional dropouts are associated with an economic effect of between $750 million and$1.35 billion per year. Results also indicate that school discipline is associated with approximately 6,600 grade retentions per year in the state of Texas. The delayed workforce entry related to grade retention has an effect of over $100 million for the state, including$5.7 million in lost tax revenue. Given the higher discipline rate for minorities, these costs disproportionately affect them. Further, the additional year of instruction costs the state over $76 million dollars

EPINEST, an agent-based model to simulate epidemic dynamics in large-scale poultry production and distribution networks

The rapid intensification of poultry production raises important concerns about the associated risks of zoonotic infections. Here, we introduce EPINEST (EPIdemic NEtwork Simulation in poultry Transportation systems): an agent-based modelling framework designed to simulate pathogen transmission within realistic poultry production and distribution networks. We provide example applications to broiler production in Bangladesh, but the modular structure of the model allows for easy parameterization to suit specific countries and system configurations. Moreover, the framework enables the replication of a wide range of eco-epidemiological scenarios by incorporating diverse pathogen life-history traits, modes of transmission and interactions between multiple strains and/or pathogens. EPINEST was developed in the context of an interdisciplinary multi-centre study conducted in Bangladesh, India, Vietnam and Sri Lanka, and will facilitate the investigation of the spreading patterns of various health hazards such as avian influenza, Campylobacter, Salmonella and antimicrobial resistance in these countries. Furthermore, this modelling framework holds potential for broader application in veterinary epidemiology and One Health research, extending its relevance beyond poultry to encompass other livestock species and disease systems