Analysis of a distributed fiber-optic temperature sensor using single-photon detectors

We demonstrate a high-accuracy distributed fiber-optic temperature sensor using superconducting nanowire single-photon detectors and single-photon counting techniques. Our demonstration uses inexpensive single-mode fiber at standard telecommunications wavelengths as the sensing fiber, which enables extremely low-loss experiments and compatibility with existing fiber networks. We show that the uncertainty of the temperature measurement decreases with longer integration periods, but is ultimately limited by the calibration uncertainty. Temperature uncertainty on the order of 3 K is possible with spatial resolution of the order of 1 cm and integration period as small as 60 seconds. Also, we show that the measurement is subject to systematic uncertainties, such as polarization fading, which can be reduced with a polarization diversity receiver

Off-diagonal hyperfine interaction between the 6p1/2 and 6p3/2 levels in 133Cs

The off-diagonal hyperfine interaction between the 6p1/2 and 6p3/2 states in 133Cs is evaluated in third-order MBPT giving 37.3 Hz and 48.3 Hz, respectively, for second-order energies of the 6p3/2 F=3 and F=4 levels. This result is a factor of 10 smaller than one obtained from an uncorrelated first-order Dirac-Hartree-Fock calculation and used in the analysis of a recent high-precision (< 2 kHz) measurement of the 6p3/2 hyperfine structure [Gerginov et al. Phys. Rev. Lett. 91, 72301 (2003)]. The factor of 10 difference has negligible effect on the conclusions of the recent experiment but will become important for experiments carried out at a precision of better than 1 kHz

A linear systems analysis of the yaw dynamics of a dynamically scaled insect model

Recent studies suggest that fruit flies use subtle changes to their wing motion to actively generate forces during aerial maneuvers. In addition, it has been estimated that the passive rotational damping caused by the flapping wings of an insect is around two orders of magnitude greater than that for the body alone. At present, however, the relationships between the active regulation of wing kinematics, passive damping produced by the flapping wings and the overall trajectory of the animal are still poorly understood. In this study, we use a dynamically scaled robotic model equipped with a torque feedback mechanism to study the dynamics of yaw turns in the fruit fly Drosophila melanogaster. Four plausible mechanisms for the active generation of yaw torque are examined. The mechanisms deform the wing kinematics of hovering in order to introduce asymmetry that results in the active production of yaw torque by the flapping wings. The results demonstrate that the stroke-averaged yaw torque is well approximated by a model that is linear with respect to both the yaw velocity and the magnitude of the kinematic deformations. Dynamic measurements, in which the yaw torque produced by the flapping wings was used in real-time to determine the rotation of the robot, suggest that a first-order linear model with stroke-average coefficients accurately captures the yaw dynamics of the system. Finally, an analysis of the stroke-average dynamics suggests that both damping and inertia will be important factors during rapid body saccades of a fruit fly

Computer program to assess impact of fatigue and fracture criteria on weight and cost of transport aircraft

A preliminary design analysis tool for rapidly performing trade-off studies involving fatigue, fracture, static strength, weight, and cost is presented. Analysis subprograms were developed for fatigue life, crack growth life, and residual strength; and linked to a structural synthesis module which in turn was integrated into a computer program. The part definition module of a cost and weight analysis program was expanded to be compatible with the upgraded structural synthesis capability. The resultant vehicle design and evaluation program is named VDEP-2. It is an accurate and useful tool for estimating purposes at the preliminary design stage of airframe development. A sample case along with an explanation of program applications and input preparation is presented

Silicon Solar Cell Process Development, Fabrication and Analysis, Phase 1

Solar cells from RTR ribbons, EFG (RF and RH) ribbons, dendritic webs, Silso wafers, cast silicon by HEM, silicon on ceramic, and continuous Czochralski ingots were fabricated using a standard process typical of those used currently in the silicon solar cell industry. Back surface field (BSF) processing and other process modifications were included to give preliminary indications of possible improved performance. The parameters measured included open circuit voltage, short circuit current, curve fill factor, and conversion efficiency (all taken under AM0 illumination). Also measured for typical cells were spectral response, dark I-V characteristics, minority carrier diffusion length, and photoresponse by fine light spot scanning. the results were compared to the properties of cells made from conventional single crystalline Czochralski silicon with an emphasis on statistical evaluation. Limited efforts were made to identify growth defects which will influence solar cell performance

Alteration of Perceptions of Safety Before and After Fit Testing among College of Dentistry Students

The COVID-19 pandemic has changed how hospitals and healthcare academic programs operate. This change has restricted services provided as well as educational opportunities for those training to be in healthcare. Further, personal protective equipment (PPE) has been required to help protect workers potentially having contact with patients who may have COVID-19. Dentistry workers are at particularly high risk due to repeated and continuous aerosol generating procedures. Healthcare students have traditionally been restricted to areas with minimal risk during clinical experiences; however, with the exposure occurring ubiquitously, avoiding the risk is nearly impossible. There is no uniform inclusion of students in respiratory protection programs within medical colleges currently; this limits knowledge surrounding perceptions of safety and application of safety behaviors by this population. To address this gap, we performed a cross-sectional study using a population of recently fit-tested dentistry students to gauge if safety perceptions change before and after being fit tested with N95 respirators. Sixty-five students completed pre- and post- fit testing for N95 personal respirators questionnaires. Over half of the participants (n=41) responded that their perception of safety changed from pre-fit testing to post-fit testing. All participants (n=65) responded that they knew how to wear an N95 respirator after fit testing. There was no significance found between pre- and post- fit responses on additional paired questions (p=0.313 and p=0.131). This data supports that fit testing for N95 respirators alters safety perceptions in this population and demonstrates the need to educate students regarding exposures in their educational environment

Formal definition of the Lower Jurassic McCoy Brook Formation, Fundy Rift Basin, eastern Canada

The name McCoy Brook Formation, presently in informal use, is formally proposed to designate outcrops of Lower Jurassic (Hettangian-Pliensbachian) strata overlying the North Mountain Basalt in the structural Minas Subbasin of the Fundy Rift Basin. It is also proposed that this designation be extended to include stratigraphically equivalent strata beneath the Bay of Fundy throughout the entire Fundy Rift Basin. It is further recommended that use of the name Scots Bay Formation, the current designation for post-basalt Jurassic sediments outcropping on the south side of the Minas Subbasin, be discontinued. The name Scots Bay Member of the McCoy Brook Formation is used here to designate distinctive lacustrine strata at the base of the McCoy Brook Formation outcropping on both sides of the Minas Subbasin. R&#xC9;SUM&#xC9; On propose officiellement le nom de Formation de McCoy Brook, qui est pr&#xE9;sentement utilise de mani&#xE8;re officieuse, pour d&#xE9;signer les affleurements ou les strates du Jurassique inf&#xE9;rieur (Hettangien-Pliensbachien) recouvrant le basalte du mont North dans le sous-bassin structurel Minas du bassin d'effondrement Fundy. Il est en outre propos&#xE9; que l’on &#xE9;tende ce nom pour qu'il cnglobe les strates stratigraphiquement &#xE9;quivalentes sous la baie de Fundy dans l'ensemble du bassin d'effondrement Fundy. Il est par ailleurs recommand&#xE9; que l'on cesse d'utiliser le nom de Formation de Scots Bay, nom actuel de l'affleurement de s&#xE9;diments du Jurassique post&#xE9;rieur au basalte sur la rive sud du sous-bassin Minas. On utilise ici le nom de membre Scots Bay de la Formation de McCoy Brook pour d&#xE9;signer les strates lacustres caract&#xE9;ristiques &#xE0; la base de l'affleurement de la Formation de McCoy Brook sur les deux rives du sous-basin Minas. [Traduit par la r&#xE9;daction

Investigation of the enhanced spatial density of submicron lunar ejecta between L values 1.2 and 3.0 in the earth's magnetosphere: Theory

Initial results from the measurement conducted by the dust particle experiment on the lunar orbiting satellite Lunar Explorer 35 (LE 35) were reported with the data interpreted as indicating that the moon is a significant source of micrometeroids. Primary sporadic and stream meteoroids impacting the surface of the moon at hypervelocity was proposed as the source of micron and submicron particles that leave the lunar craters with velocities sufficient to escape the moon's gravitational sphere of influence. No enhanced flux of lunar ejecta with masses greater than a nanogram was detected by LE 35 or the Lunar Orbiters. Hypervelocity meteoroid simulation experiments concentrating on ejecta production combined with extensive analyses of the orbital dynamics of micron and submicron lunar ejecta in selenocentric, cislunar, and geocentric space have shown that a pulse of these lunar ejecta, with a time correlation relative to the position of the moon relative to the earth, intercepts the earth's magnetopause surface (EMPs). As shown, a strong reason exists for expecting a significant enhancement of submicron dust particles in the region of the magnetosphere between L values of 1.2 and 3.0. This is the basis for the proposal of a series of experiments to investigate the enhancement or even trapping of submicron lunar ejecta in this region. The subsequent interaction of this mass with the upper-lower atmosphere of the earth and possible geophysical effects can then be studied