Quantum-Noise Power Spectrum of Fields with Discrete Classical Components

We present an algorithmic approach to calculate the quantum-noise spectral density of photocurrents generated by optical fields with arbitrary discrete classical spectrum in coherent or squeezed states. The measurement scheme may include an arbitrary number of demodulations of the photocurrent. Thereby, our method is applicable to the general heterodyne detection scheme which is implemented in many experiments. For some of these experiments, e.g. in laser-interferometric gravitational-wave detectors, a reliable prediction of the quantum noise of fields in coherent and squeezed states plays a decisive role in the design phase and detector characterization. Still, our investigation is limited in two ways. First, we only consider coherent and squeezed states of the field and second, we demand that the photocurrent depends linearly on the field's vacuum amplitudes which means that at least one of the classical components is comparatively strong.Comment: 8 pages, 2 figure

Experimental demonstration of higher-order Laguerre-Gauss mode interferometry

The compatibility of higher-order Laguerre-Gauss (LG) modes with interferometric technologies commonly used in gravitational wave detectors is investigated. In this paper we present the first experimental results concerning the performance of the LG33 mode in optical resonators. We show that the Pound-Drever-Hall error signal for a LG33 mode in a linear optical resonator is identical to that of the more commonly used LG00 mode, and demonstrate the feedback control of the resonator with a LG33 mode. We succeeded to increase the mode purity of a LG33 mode generated using a spatial-light modulator from 51% to 99% upon transmission through a linear optical resonator. We further report the experimental verification that a triangular optical resonator does not transmit helical LG modes

Exercises integrating reading skills with social studies for third grade

Thesis (Ed.M.)--Boston Universit

Higher order Laguerre-Gauss mode degeneracy in realistic, high finesse cavities

Higher order Laguerre-Gauss (LG) beams have been proposed for use in future gravitational wave detectors, such as upgrades to the Advanced LIGO detectors and the Einstein Telescope, for their potential to reduce the effects of the thermal noise of the test masses. This paper details the theoretical analysis and simulation work carried out to investigate the behaviour of LG beams in realistic optical setups, in particular the coupling between different LG modes in a linear cavity. We present a new analytical approximation to compute the coupling between modes, using Zernike polynomials to describe mirror surface distortions. We apply this method in a study of the behaviour of the LG33 mode within realistic arm cavities, using measured mirror surface maps from the Advanced LIGO project. We show mode distortions that can be expected to arise due to the degeneracy of higher order spatial modes within such cavities and relate this to the theoretical analysis. Finally we identify the mirror distortions which cause significant coupling from the LG33 mode into other order 9 modes and derive requirements for the mirror surfaces.Comment: 12 pages Submitted to PRD 19/07/201

Antidotal potential of specific diets in Norway rats

Jacob, J., Freise, J.F

Experimental test of higher-order Laguerre–Gauss modes in the 10 m Glasgow prototype interferometer

Brownian noise of dielectric mirror coatings is expected to be one of the limiting noise sources, at the peak sensitivity, of next generation ground based interferometric gravitational wave (GW) detectors. The use of higher-order Laguerre–Gauss (LG) beams has been suggested to reduce the effect of coating thermal noise in future generations of gravitational wave detectors. In this paper we describe the first test of interferometry with higher-order LG beams in an environment similar to a full-scale gravitational wave detector. We compare the interferometric performance of higher-order LG modes and the fundamental mode beams, injected into a 10 m long suspended cavity that features a finesse of 612, a value chosen to be typical of future gravitational wave detectors. We found that the expected mode degeneracy of the injected LG3, 3 beam was resolved into a multiple peak structure, and that the cavity length control signal featured several nearby zero crossings. The break up of the mode degeneracy is due to an astigmatism (defined as |Rcy − Rcx|) of 5.25 ± 0.5 cm on one of our cavity mirrors with a radius of curvature (Rc) of 15 m. This observation agrees well with numerical simulations developed with the FINESSE software. We also report on how these higher-order mode beams respond to the misalignment and mode mismatch present in our 10 m cavity. In general we found the LG3, 3 beam to be considerably more susceptible to astigmatism and mode mismatch than a conventional fundamental mode beam. Therefore the potential application of higher-order Laguerre–Gauss beams in future gravitational wave detectors will impose much more stringent requirements on both mode matching and mirror astigmatism

Double layer in ionic liquids: Overscreening vs. crowding

We develop a simple Landau-Ginzburg-type continuum theory of solvent-free ionic liquids and use it to predict the structure of the electrical double layer. The model captures overscreening from short-range correlations, dominant at small voltages, and steric constraints of finite ion sizes, which prevail at large voltages. Increasing the voltage gradually suppresses overscreening in favor of the crowding of counterions in a condensed inner layer near the electrode. The predicted ion profiles and capacitance-voltage relations are consistent with recent computer simulations and experiments on room-temperature ionic liquids, using a correlation length of order the ion size.Comment: 4 pages + supplementary informatio

ranacapa: An R package and Shiny web app to explore environmental DNA data with exploratory statistics and interactive visualizations.

Environmental DNA (eDNA) metabarcoding is becoming a core tool in ecology and conservation biology, and is being used in a growing number of education, biodiversity monitoring, and public outreach programs in which professional research scientists engage community partners in primary research. Results from eDNA analyses can engage and educate natural resource managers, students, community scientists, and naturalists, but without significant training in bioinformatics, it can be difficult for this diverse audience to interact with eDNA results. Here we present the R package ranacapa, at the core of which is a Shiny web app that helps perform exploratory biodiversity analyses and visualizations of eDNA results. The app requires a taxonomy-by-sample matrix and a simple metadata file with descriptive information about each sample. The app enables users to explore the data with interactive figures and presents results from simple community ecology analyses. We demonstrate the value of ranacapa to two groups of community partners engaging with eDNA metabarcoding results

Antikoagulantien-Resistenz bei kommensalen Nagern

Zusammenfassung Punktmutationen im Gen VKORC1 vermitteln Resistenz gegenüber Antikoagulantien und bilden damit die Voraussetzung für die Entwicklung rodentizidresistenter Wanderratten- und Hausmauspopulationen. In verschiedenen geographischen Regionen sind an unterschiedlichen Positionen des Gens jeweils gebietsspezifische Mutationen mehrfach unabhängig entstanden. Während Hausmäuse auch mit Akutgift (Zinkphosphid) oder bei kleineren Vorkommen mit Fallen bekämpft werden können, sind Antikoagulantien derzeit die einzigen verfügbaren Mittel zur wirksamen Bekämpfung von Wanderratten. Die Mutation vermittelt Resistenz gegenüber Warfarin, wobei die Erfahrung zeigt, dass bei anhaltendem Selektionsdruck innerhalb kurzer Zeit nach dem ersten Auftreten von Warfarin-Resistenz auch Resistenzprobleme gegenüber anderen Wirkstoffen (Chlorphacinon, Coumatetralyl, Bromadiolon und teilweise Difenacoum) auftreten. Somit sind fünf der acht in Deutschland zugelassenen Wirkstoffe der Antikoagulantien betroffen. Neu entwickelte molekulargenetische Resistenztests können nicht nur mit Gewebe, sondern auch mit Kotproben der Nager durchgeführt werden und erlauben eine vollständig nicht–invasive Probenahme. Sie bieten eine relativ einfache und zeitsparende Methodik für das Resistenzmonitoring bei Wanderratten und Hausmäusen. In Zusammenarbeit mit verschiedenen Institutionen und Privatpersonen wurde unter Anwendung dieser Methodik in den Jahren 2005 bis 2008 ein Wanderratten-Resistenzmonitoring mit Schwerpunkt Nordwestdeutschland durchgeführt. Die Ergebnisse zeigen, dass sich das nordwestdeutsche Resistenzgebiet mittlerweile auf rund 25.000 km2 ausgedehnt hat und damit etwa 7 % der Fläche Deutschlands einnimmt. Sobald sich die Resistenzmutation etabliert hat, lassen sich Wanderrattenpopulationen mit den betroffenen Wirkstoffen nicht mehr in der gewohnt effizienten Weise bekämpfen. Es muss dann auf die hochpotenten Wirkstoffe Brodifacoum, Flocoumafen und Difethialon zurückgegriffen werden, bei deren Anwendung, gute Köderannahme vorausgesetzt, keine Bekämpfungsprobleme zu erwarten sind. Besonders in den Randbereichen des Resistenzgebietes müssen die betroffenen Anwender rechtzeitig informiert werden, um eine erfolgreiche Schadnagerbekämpfung zu gewährleisten und die Ausbringung unwirksamer Rodentizide zu vermeiden. Außerhalb des Resistenzgebietes sollten die geringer toxischen und weniger persistenten Wirkstoffe der Antikoagulantiern bevorzugt zur Anwendung kommen