The study of plasmonics in nanohole metallic metamaterials

Plasmonics is the study of light-matter interaction. The interaction of incident light (photons) with surface plasmons present in metamaterials results in unique optical properties. Nanohole arrays are a metamaterial consisting of an array of sub-wavelength holes perforated in an optically thin metallic film which resides upon a dielectric material. The interaction of light with the surface plasmons present in the nanohole array leads to extraordinary optical transmission which produces resonance peaks with a higher intensity than the incident light. By changing the physical parameters of the nanohole array, such as hole size and periodicity, the resonance peaks can be tuned to different locations. This is used in applications such as surface plasmon resonance sensing and surface enhanced Raman spectroscopy studied in this thesis. Previous derivations of transmission and absorption coefficients show that the transmission is only dependent on the periodicity of the nanohole array. However, numerous simulated and experimental results have shown that the periodicity and hole size have an effect on the transmission and absorption of nanohole arrays

Tunable 3D Plasmonic Cavity Nanosensors for Surface-enhanced Raman Spectroscopy with Sub Femtomolar Limit of Detection

Metallic nanohole arrays (NHAs) with a high hole density have emerged with potential applications for surface-enhanced Raman spectroscopy (SERS) including the detection of analytes at ultra-low concentrations. However, these NHA structures generally yield weak localized surface plasmon resonance (LSPR) which is a prerequisite for SERS measurements. In this work, a compact three-dimensional (3D) tunable plasmonic cavity with extraordinary optical transmission properties serves as a molecular sensor with sub-femtomolar detection. The 3D nanosensor consists of a gold film containing a NHA with an underlying cavity and a gold nanocone array at the bottom of the cavity. These nanosensors provide remarkable surface plasmon polariton (SPP) and LSPR coupling resulting in a significantly improved detection performance. The plasmonic tunability is evaluated both experimentally and theoretically. A SERS limit of detection of 10-16 M for 4-Nitrothiophenol (4-NTP) is obtained along with distribution mapping of the molecule on the 3D plasmonic nanosensor. This results in an improved SERS enhancement factor (EF) of 106 obtained from a femtolitre plasmonic cavity volume. The tunability of these sensors can give rise to a potential opportunity for use in optical trapping while providing SERS sensing of a molecule of interest

Measures of a sustainable commute as a predictor of happiness

The ways in which we travel—by what mode, for how long, and for what purpose—can affect our sense of happiness and well-being. This paper assesses the relationships between measures of the sustainability of transportation systems in U.S. metropolitan areas and subjective well-being. Associations between self-reported happiness levels from the Gallup Healthways Well-being Index and commute data were examined for 187 core-based statistical areas (CBSA). Wealsosupplementthisquantitativeanalysisthroughbriefcasestudiesofhigh-andlow-performing happiness cities. Our quantitative results indicate that regions with higher commute mode shares by non-automobile modes generally had higher well-being scores, even when controlling for important economic predictors of happiness. We also find that pro-sustainable transportation policies can have implications for population-wide happiness and well-being. Our case studies indicate that both high and low scoring happiness cities demonstrate a dedicated commitment to improving sustainable transportation infrastructure. Our study suggests that cities that provide incentives for residents to use more sustainable commute modes may offer greater opportunity for happiness than those that do not

Philosophers and their body : biographical tradictions and the building of the philosopher’s persona in Diogenes Laertius

À partir de l’analyse des traditions biographiques compilées et conservées par Diogène Laërce, cette thèse cherche à évaluer l’intérêt des anecdotes mettant en scène le corps des philosophes dans l’élaboration d’une figure du philosophe idéal ou bien dans la construction de la personne du philosophe. Si les philosophes anciens nous sont avant tout connus comme un ensemble de textes ou de systèmes doctrinaux, les témoignages biographiques antiques fournissent en effet également la mémoire de pratiques corporelles ou d’interrogations sur certaines pratiques corporelles (régime alimentaire, activité physique, vêtement, santé) qu’il convient d’analyser. Cette étude vise à savoir dans quelle mesure et de quelles manières le corps peut être compris comme un terrain de mise en pratique de théories ou de préceptes philosophiques, et par la même, de voir comment le corps intervient dans la reconnaissance du philosophe. Cette recherche envisage successivement ce que peut être un régime de vie philosophique (vêtement, barbe et pilosité, accessoires) avant d’interroger le rapport des philosophes à leurs propres corps mortels (maladie, vieillesse et mort). L’enquête aussi à une lecture pragmatique de l’œuvre de Diogène Laërce, envisagée comme un auteur et non comme un compilateur.Based on an analysis of the biographical traditions compiled and preserved by Diogenes Laertius, this thesis assesses the significance of anecdotes depicting the body of philosophers in the development of the figure of an ideal philosopher and in these philosopher’ building of their own persona. Whilst ancient philosophers are primarly known to us through texts and doctrinal systems, the insights into their bodily pratcices and their reflections on the subject – diet, physical activity, clothing health – which are reported in ancient biographical testimonies are also worth investigating. This study examines the extent to which and the different ways in which the body can be ssen as the field of practice for the theories and for the philosopher’s relationship to their own mortal body (disease, old age and death). The investigation also provides a pragmatic reading of the work of Diogene Laertius, considered as an author and not merely as a compiler

Montrer le corps : prouver le philosophe ? Le corps des philosophes dans la statuaire antique

After recalling the conditions of preservation and transmission of statues of Greek philosophers, the article tries in a first time to question the criteria used to identify the philosophical typein ancient statuary (seated, beard and clothing), before analyzing the meanings of sculpted bodies from the example of three statues of philosophers (Diogenes, Chrysippus, Epicurus)

64 MHz RF Exposure System for Testing of Implanted Medical Devices in MRI Applications

Currently whole-body transmit RF coils are the most common RF environment for testing. These RF exposure systems designed for testing of devices are commercially available and currently used in a clinical setting; however, even though head-only transmit/receive (TX/RCV) coils are available on MRI scanners, there is not a validated head-only RF exexposure system available for either 64 or 128 MHz. Testing of active implantable medical devices (AIMDs) is guided by the requirements described in ISO 10974:2018(E). Determining the effects radiofrequency (RF) fields have on AIMDS in an MRI system are of paramount importance. Implanted medical devices in the head and neck experience a different local electric field when being imaged head-only exexposure system. This is a significant difference in local electric field when exposed to a head-only transmit coil versus being exposed to a whole-body transmit coil. To adequately evaluate the safety of these devices in that environment, head-only RF exposure systems are needed. In this paper we summarize the steps in developing and validating a head-only RF exexposure system that is properly tuned to 64 MHz and matched to 50 ω for the testing of implanted medical devices. These steps include the methods for simulating and developing a head-only RF exexposure system

Machine Learning Predicts Aperiodic Laboratory Earthquakes

In this paper we find a pattern of aperiodic seismic signals that precede earthquakes at any time in a laboratory earthquake’s cycle using a small window of time. We use a data set that comes from a classic laboratory experiment having several stick-slip displacements (earthquakes), a type of experiment which has been studied as a simulation of seismologic faults for decades. This data exhibits similar behavior to natural earthquakes, so the same approach may work in predicting the timing of them. Here we show that by applying random forest machine learning technique to the acoustic signal emitted by a laboratory fault, we can predict the time remaining before failure with 1.61 seconds mean absolute error at any moment of earthquake’s cycle. These predictions are based solely on the acoustical signal\u27s statistical features derived from the local, moving 0.3 second time windows and do not make use of its history. Essential improvements in providing new understanding of fault physics may be brought by applying this technique to acoustic seismic data

HEAT TRANSFER LIMITATIONS IN HYDROGEN PRODUCTION VIA STEAM REFORMATION: THE EFFECT OF REACTOR GEOMETRY

ABSTRACT Hydrogen can be produced in a variety of methods including steam-reformation of hydrocarbon fuels. In past studies the quasi non-dimensional space velocity parameter (inverse residence time) has been shown to be insufficient in accurately predicting fuel conversion in hydrocarbon-steam reformation. Heat transfer limitations have been manifest with reactors of different geometries. In order to achieve ideal fuel conversion, the heat transfer limitations and the changes of these limitations with respect to geometry must be considered in the reactor design. In this investigation, axial and radial temperature profiles are presented from reactors of different aspect ratios while holding space velocity constant. Using both the temperature profile information as well as the traditional space velocity limitations one may be able to develop an optimal reactor design

Heat Transfer Limitations in Hydrogen Production Via Steam Reformation: The Effect of Reactor Geometry

Proceedings of the ASME 4th International Conference on Fuel Cell Science, Engineering and Technology, Irvine, CA, June 19 - 21, 2006Hydrogen can be produced in a variety of methods including steam-reformation of hydrocarbon fuels. In past studies the quasi non-dimensional space velocity parameter (inverse residence time) has been shown to be insufficient in accurately predicting fuel conversion in hydrocarbon-steam reformation. Heat transfer limitations have been manifest with reactors of different geometries. In order to achieve ideal fuel conversion, the heat transfer limitations and the changes of these limitations with respect to geometry must be considered in the reactor design. In this investigation, axial and radial temperature profiles are presented from reactors of different aspect ratios while holding space velocity constant. Using both the temperature profile information as well as the traditional space velocity limitations one may be able to develop an optimal reactor design

Heat Transfer Limitations in Hydrogen Production Via Steam Reformation: The Effect of Reactor Geometry

Proceedings of the ASME 4th International Conference on Fuel Cell Science, Engineering and Technology, Irvine, CA, June 19 - 21, 2006 Hydrogen can be produced in a variety of methods including steam-reformation of hydrocarbon fuels. In past studies the quasi non-dimensional space velocity parameter (inverse residence time) has been shown to be insufficient in accurately predicting fuel conversion in hydrocarbon-steam reformation. Heat transfer limitations have been manifest with reactors of different geometries. In order to achieve ideal fuel conversion, the heat transfer limitations and the changes of these limitations with respect to geometry must be considered in the reactor design. In this investigation, axial and radial temperature profiles are presented from reactors of different aspect ratios while holding space velocity constant. Using both the temperature profile information as well as the traditional space velocity limitations one may be able to develop an optimal reactor design.UCD-ITS-PS-06-01, Civil Engineering