Mach-Zehnder optical configuration with Brewster window and two quarter-wave plates

Configuration is improvement because of the following: It provides higher efficiency. It reduces or eliminates feedthrough of untranslated local oscillator, which would produce a beat signal at shifted frequency of translator. When used without translator and with low-power detector, telescope secondary mirror reflects portion of output to local oscillator

Generation of coherent magnetic fields in sheared inhomogeneous turbulence: No need for rotation?

Coherent magnetic fields are often believed to be generated by the combination of stretching by differential rotation and turbulent amplification of magnetic field, via the so-called alpha effect. The latter is known to exist in helical turbulence, which is envisioned to arise due to both rotation and convection in solar-type stars. In this contribution, a turbulent flow driven by a nonhelical inhomogeneous forcing and its kinematic dynamo action are studied for a uniform magnetic field in the background of a linear shear flow. By using a quasilinear analysis and a nonperturbative method utilizing a time-dependent wave number, turbulence property and electromotive force are computed for arbitrary shear strength. Due to the large-scale shear flow, the turbulence is highly anisotropic, as a consequence, so is the electromotive force. The latter is found to exist even without rotation due to the combined effect of shear flow and inhomogeneous forcing, containing not only the alpha effect but also magnetic pumping (the gamma effect representing a transport of magnetic flux by turbulence). Specifically, without shear, only the magnetic pumping exists, aligned with the direction of inhomogeneity. For a weak but nonzero shear, the combined effects of shear and inhomogeneous forcing modify the structure of the magnetic pumping when the inhomogeneity is in the plane of the shear flow, the magnetic pumping becoming bidimensional in that plane. It also induces an alpha tensor which has nondiagonal components. When the inhomogeneity is perpendicular to the plane of the shear flow, the alpha effect has three nonzero diagonal components and one off-diagonal component. However, for a sufficiently strong shear, the gamma and alpha effects are suppressed due to shear stabilization which damps turbulence. A simplified dynamo model is then proposed where a large-scale dynamo arises due to the combined effect of shear flow and inhomogeneous forcing. In particular, the growth of a large-scale axisymmetric magnetic field is demonstrated in case of an inhomogeneity which is perpendicular to the plane of the shear flow. Interesting implications of these results for the structure of magnetic fields in star with slow rotation are discussed. (C) 2011 American Institute of Physics. [doi:10.1063/1.3551700

Nonlinear dynamo action in a precessing cylindrical container

It is numerically demonstrated by means of a magnetohydrodynamics (MHD) code that precession can trigger the dynamo effect in a cylindrical container. This result adds credit to the hypothesis that precession can be strong enough to be one of the sources of the dynamo action in some astrophysical bodies.Comment: 5 pages, 5 figures including subfigure

Developing a podcast series to promote maternal perinatal well-being

Background: The transition to motherhood for first-time mothers can be characterised by psychological distress, which can result from inadequate support during the perinatal period. Limited accessibility to support in rural and remote areas means that it is imperative we provide accessible, online resources. To this end, the BAMBOO WebApp will pair new mums with peer mentors and provide a digital resource centre, which contains a podcast series. This research examined the development of the podcast series. Method: A collaborative auto-ethnography was used to examine the podcast creators’ environment, interactions and reflections on the recording process. This was complemented by listener interviews, wherein discussions centred on opinions and suggestions pertaining to the podcast series’ purpose, applicability, content, and design. Results: The process describing the development of the podcast series will be outlined. With data collection still underway, thematic analyses of project data will identify themes concerning its content, design, applicability, and usability. Discussion of the findings will also address how the dissemination of health information to new mothers via podcasts can be optimized. Conclusions: The project findings have broad implications concerning the impact that a podcast series within a WebApp can have on supporting maternal well-being. Additionally, findings regarding the process of translating research findings into engaging, public-facing edutainment have implications for how to better produce health education materials

A scoping review examining how music listening can support intrapartum maternal well-being

Background: How might music listening support intrapartum well-being for mothers, when this period can be distressing for first time mothers? Moreover, what type of music listening resources are shown to support maternal intrapartum well-being? We have undertaken a scoping review to consolidate evidence-based knowledge on the role of music listening for maternal intrapartum well-being. Method: The PRISMA-ScR protocol was followed (Tricco et al., 2018). English language, peerreviewed publications between 2000 and 2023 about research specifically related to music listening were examined following a keyword search (music AND listen*, AND (spellings of) perinatal OR prenatal OR prenatal OR pregnan* OR labour OR birth OR antepartum OR intrapartum). Articles focused only on interventions other than music listening (e.g., music therapy, group lessons, and singing) and those focused only on fertility, contraception, or child outcomes were excluded. Results: Preliminary findings suggest that the impact of music listening can be grouped under three themes: while pregnant (e.g., reducing stress, anxiety and depression and improving sleep quality; while in labour (reducing mothers’ stress, anxiety, and fears, providing a distraction, reducing pain/medication), and regarding longer-term consequences (increasing maternal-infant bonding and self-efficacy, decreasing the risk of postanal depression). Conclusions: While there is varied reporting regarding the stimuli or resources used in these studies; consolidating the evidence-based music listening resources will result in an online resource centre for mothers. Doing so affords expectant mothers (especially those residing in rural and remote communities) access to low-cost, evidence-based resources, aimed at promoting their well-being pre-/post-natally

The mean electromotive force due to turbulence of a conducting fluid in the presence of mean flow

The mean electromotive force caused by turbulence of an electrically conducting fluid, which plays a central part in mean--field electrodynamics, is calculated for a rotating fluid. Going beyond most of the investigations on this topic, an additional mean motion in the rotating frame is taken into account. One motivation for our investigation originates from a planned laboratory experiment with a Ponomarenko-like dynamo. In view of this application the second--order correlation approximation is used. The investigation is of high interest in astrophysical context, too. Some contributions to the mean electromotive are revealed which have not been considered so far, in particular contributions to the $\alpha$--effect and related effects due to the gradient of the mean velocity. Their relevance for dynamo processes is discussed. In a forthcoming paper the results reported here will be specified to the situation in the laboratory and partially compared with experimental findings.Comment: 16 pages, 2 figures, in PRE pres

On the Bekenstein-Hawking Entropy, Non-Commutative Branes and Logarithmic Corrections

We extend earlier work on the origin of the Bekenstein-Hawking entropy to higher-dimensional spacetimes. The mechanism of counting states is shown to work for all spacetimes associated with a Euclidean doublet $(E_1,M_1)+(E_2,M_2)$ of electric-magnetic dual brane pairs of type II string-theory or M-theory wrapping the spacetime's event horizon plus the complete internal compactification space. Non-Commutativity on the brane worldvolume enters the derivation of the Bekenstein-Hawking entropy in a natural way. Moreover, a logarithmic entropy correction with prefactor 1/2 is derived.Comment: 17 pages, 2 figures; refs. adde

Development and testing of laser Doppler system components for wake vortex monitoring. Volume 1: Scanner development, laboratory and field testing and system modeling

A servo-controlled range/elevation scanner for the laser Doppler velocimeter (LDV) was developed and tested in the field to assess its performance in detecting and monitoring aircraft trailing vortices in an airport environment. The elevation scanner provides a capability to manually point the LDV telescope at operator chosen angles from 3.2 deg. to 89.6 deg within 0.2 deg, or to automatically scan the units between operator chosen limits at operator chosen rates of 0.1 Hz to 0.5 Hz. The range scanner provides a capability to manually adjust the focal point of the system from a range of 32 meters to a range of 896 meters under operator control, or to scan between operator chosen limits and at rates from 0.1 Hz to 6.9 Hz. The scanner controls are designed to allow simulataneous range and elevation scanning so as to provide finger scan patterns, arc scan patterns, and vertical line scan patterns. The development and testing of the unit is discussed, along with a fluid dynamic model of the wake vortex developed in a laser Doppler vortex sensor simulation program

Recognizing Personality Characteristics Related to Managerial Potential in Agriculture

This study was exploratory in nature. The sample was too· small to provide conclusive, refined prediction instruments. Given these limitations, however, the utilized approach indicates that farmers lacking personality characteristics necessary to become successful managers can be identified. However, additional testing and consideration of other independent variables may develop more reliable relationships than were developed in this study