Optomechanical Stochastic Resonance in a Macroscopic Torsion Oscillator

Linear mechanical oscillators have been applied to measure very small forces, mostly with the help of noise suppression. In contrast, adding noise to non-linear oscillators can improve the measurement conditions. Here, this effect of stochastic resonance is demonstrated in a macroscopic torsion oscillator, for an optomechanical non-linear potential. The signal output is enhanced for a sub-threshold electronic signal. This non-linear oscillator serves as a model system for the enhancement of signal-to-noise ratio in high precision optomechanical experiments.Comment: 4 pages (double column), 3 figure

Characterization of Neuroimage Coupling Between EEG and FMRI Using Within-Subject Joint Independent Component Analysis

The purpose of this dissertation was to apply joint independent component analysis (jICA) to electroencephalography (EEG) and functional magnetic resonance imaging (fMRI) to characterize the neuroimage coupling between the two modalities. EEG and fMRI are complimentary imaging techniques which have been used in conjunction to investigate neural activity. Understanding how these two imaging modalities relate to each other not only enables better multimodal analysis, but also has clinical implications as well. In particular, Alzheimer’s, Parkinson’s, hypertension, and ischemic stroke are all known to impact the cerebral blood flow, and by extension alter the relationship between EEG and fMRI. By characterizing the relationship between EEG and fMRI within healthy subjects, it allows for comparison with a diseased population, and may offer ways to detect some of these conditions earlier. The correspondence between fMRI and EEG was first examined, and a methodological approach which was capable of informing to what degree the fMRI and EEG sources corresponded to each other was developed. Once it was certain that the EEG activity observed corresponded to the fMRI activity collected a methodological approach was developed to characterize the coupling between fMRI and EEG. Finally, this dissertation addresses the question of whether the use of jICA to perform this analysis increases the sensitivity to subcortical sources to determine to what degree subcortical sources should be taken into consideration for future studies. This dissertation was the first to propose a way to characterize the relationship between fMRI and EEG signals using blind source separation. Additionally, it was the first to show that jICA significantly improves the detection of subcortical activity, particularly in the case when both physiological noise and a cortical source are present. This new knowledge can be used to design studies to investigate subcortical signals, as well as to begin characterizing the relationship between fMRI and EEG across various task conditions

LAPR: An experimental aircraft pushbroom scanner

A three band Linear Array Pushbroom Radiometer (LAPR) was built and flown on an experimental basis by NASA at the Goddard Space Flight Center. The functional characteristics of the instrument and the methods used to preprocess the data, including radiometric correction, are described. The radiometric sensitivity of the instrument was tested and compared to that of the Thematic Mapper and the Multispectral Scanner. The radiometric correction procedure was evaluated quantitatively, using laboratory testing, and qualitatively, via visual examination of the LAPR test flight imagery. Although effective radiometric correction could not yet be demonstrated via laboratory testing, radiometric distortion did not preclude the visual interpretation or parallel piped classification of the test imagery

Status Consumption and the Millennial Consumer: An Exploratory Study

This paper focuses on millennial consumers’ perceptions about the motivation to purchase luxury and status items for the young working professional. It defines and addresses the relationship between status symbols and what drives the millennial generation’s purchases and desires to purchase. Research was conducted through a detailed literature review, qualitative pre-test and focus group. Through the pre-test, themes of luxury and status items were found. Common product categories to represent status items included: accessories, clothing, technology, travel, pet ownership, home ownership, expensive cars, and entertainment. The focus group was conducted in a classroom setting discussion with thirty students. Students participating in the focus group were asked various open-ended questions regarding what products and brands they consider luxury and status items for the young working professional as well as questions regarding perceptions and motivations when it comes to the purchase of these products. The results of the focus group matched well with the themes provided in the pre-test and provided more specific products as well as information regarding perceptions of those who purchase these items and the motivation behind the purchase. When it came to how focus group participants perceive those who buy and display these status items to the public, both positive and negative opinions were expressed. When asked what participants think about young working professionals who display status items, the collective opinion tended to be more negative than positive. However, when asked how participants would feel about themselves if they owned these status items, reactions were more positive

Efficient coupling to an optical resonator by exploiting time-reversal symmetry

The interaction of a cavity with an external field is symmetric under time reversal. Thus, coupling to a resonator is most efficient when the incident light is the time reversed version of a free cavity decay, i.e. when it has a rising exponential shape matching the cavity lifetime. For light entering the cavity from only one side, the maximally achievable coupling efficiency is limited by the choice of the cavity mirrors' reflectivities. Such an empty-cavity experiment serves also as a model system for single-photon single-atom absorption dynamics. We present experiments coupling exponentially rising pulses to a cavity system which allows for high coupling efficiencies. The influence of the time constant of the rising exponential is investigated as well as the effect of a finite pulse duration. We demonstrate coupling 94% of the incident TEM00 mode into the resonator.Comment: 7 pages, 5 figure

Académie impériale de l’Opéra: Tannhäuser, Opéra en trois actes, de Richard Wagner

Transcript of ACADÉMIE IMPÉRIALE DE L’OPÉRA: TANNHÄUSER, OPÉRA EN TROIS ACTES, DE RICHARD WAGNER, by Jacques-Léopold Heugel, appearing in LE MÉNESTREL, 17 mars 1861, pp. 121 -123

Classical many-body time crystals

Discrete time crystals are a many-body state of matter where the extensive system's dynamics are slower than the forces acting on it. Nowadays, there is a growing debate regarding the specific properties required to demonstrate such a many-body state, alongside several experimental realizations. In this work, we provide a simple and pedagogical framework by which to obtain many-body time crystals using parametrically coupled resonators. In our analysis, we use classical period-doubling bifurcation theory and present a clear distinction between single-mode time-translation symmetry breaking and a situation where an extensive number of degrees of freedom undergo the transition. We experimentally demonstrate this paradigm using coupled mechanical oscillators, thus providing a clear route for time crystals realizations in real materials.Comment: 23 pages, 5 figures, comments are welcom

SEMAINE THÉÂTRALE ET MUSICALE .

Transcript of SEMAINE THÉÂTRALE ET MUSICALE by Arthur Pougin and Henri Heugel, appearing in LE MÉNESTREL, 7 mars 1875, pp. 106-108