4,632 research outputs found

    Evolution of Subjective Hurricane Risk Perceptions: A Bayesian Approach

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    This paper studies how individuals update subjective risk perceptions in response to hurricane track forecast information, using a unique data set from an event market, the Hurricane Futures Market (HFM). We derive a theoretical Bayesian framework which predicts how traders update their perceptions of the probability of a hurricane making landfall in a certain range of coastline. Our results suggest that traders behave in a way consistent with Bayesian updating but this behavior is based on the perceived quality of the information received.risk perceptions, learning, Bayesian learning, event markets, prediction markets, favorite-longshot bias, hurricanes

    Optimal Crop-Insurance Strategies under Climate Variability: Contrasting Insurer and Farmer Interests

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    This study analyzes the potential synergies and conflicts of interest between farmers and insurers in the selection of an optimal crop insurance contract. Special attention is given to how climate information influences this decision-making process. To do so, we consider a representative 40 hectares, rainfed, cotton-peanut farm located in Jackson County in Florida. Our results show that year-to-year ENSO-based climate variability affects farmers income and insurers gains according to crop insurance contracts. Additionally, introduction of ENSO-based climate forecasts presents a significant impact on the selection of a particular contract. We conclude that insurers and farmers can bridge their divergent interests by improving their understanding of the effect of climate conditions on the development of sustainable business plans.Environmental Economics and Policy, Risk and Uncertainty,

    Lucuma as an exotic high quality fruit imported into Portugal and the UE

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    This project has two different goals, one of them is to promote the consumption of exotic fruits with high quality. The other goal of the project is to look for the viability of turning this work project into a real business, focusing in two different channels to diversify its revenues: B2B and B2C. In order to achieve this second goal, this project aims to see the best way to commercialize this product (Lucuma powder and Pulp of Lucuma) and how to make it in an efficient way with right companies. Therefore, the project aims to create a company to commercialize the product between the producers in Peru and possibly small businesses interested in acquire the processed fruit and also individuals interested in own consumption in small quantities. This project, if successful, tries to diversify the consumption into other good organic healthy products in the long-term

    Solitons in Bose-Einstein condensates

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    Treballs Finals de Grau de Física, Facultat de Física, Universitat de Barcelona, Curs: 2022, Tutor: Ricardo Mayol SánchezIn this report we investigate the instability of a dark soliton imprinted in a twodimensional Bose-Einstein condensate. We have shown that depending on the form of the imprinted phase step, the soliton bends and then, via a snake instability, it decays into vortices. We have performed numerical simulations of the time evolution of the imprinted dark soliton in two-dimensions. Finally, we have qualitatively interpreted the theoretical framework that describes this phenomenon in the approximation of weakly interacting boson

    Bleach Imaged Plasmon Propagation (BIIPP) in Single Gold Nanowires

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    Here, we present a novel approach to visualize propagating surface plasmon polaritons through plasmon-exciton interactions between single gold nanowires and a thin film of a fluorescent polymer. A plasmon polariton was launched by exciting one end of a single gold nanowire with a 532 nm laser. The local near-field of the propagating plasmon modes caused bleaching of the polymer emission. The degree of photobleaching along the nanowire could be correlated with the propagation distance of the surface plasmon polaritons. Using this method of bleach-imaged plasmon propagation (BIIPP), we determined a plasmon propagation distance of 1.8 ± 0.4 μm at 532 nm for chemically grown gold nanowires. Our results are supported by finite difference time domain electromagnetic simulations

    Climate Variability and Agricultural Productivity: Evidence from Southeastern US

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    The goal of this study is to empirically evaluate the extent to which agricultural productivity estimates are affected by variation on climate. To do so, we explore the case of the agricultural sector in the Southeast US. This geographical region is influenced seasonally by the El Niño Southern Oscillation (ENSO) phenomena making it ideal for studying the interaction of climate variability and agricultural productivity. Although, different methodologies have been developed to study TE the stochastic production frontier (SPF) approach offers several advantages over other available alternatives (Kumbhakar and Lovell 2003). Thus, to assess the impact of climatic on TE we estimate alternative SPF models with and without climatic variables. We also test alternative variables to measure the influence of climate on TE; namely, seasonal rain fall and the ENSO phase.Climate Variability, Productivity, US, Production Economics,

    Maximum-Likelihood Estimation of Glandular Fraction for Mammography and its Effect on Microcalcification Detection

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    Objective: Breast tissue is a mixture of adipose and fibro-glandular tissue. The risk of undetected breast cancer increases with the amount of glandular tissue in the breast. Therefore, radiologists need to know quantitative glandular fraction when diagnosing a patient. Another increasingly popular mammography protocol is eliminating the anti-scatter grid and using software algorithms to reduce scatter. This work uses a Maximum Likelihood Expectation Maximization algorithm to estimate the pixel-wise glandular fraction from images taken with an anti-scatter grid or with scatter removed algorithmically. The work also studies if presenting the pixel-wise glandular fraction image alongside the usual mammography image has the potential to improve micro-calcification detection. Approach: The algorithms are implemented and evaluated with TOPAS Geant4-generated images with known glandular fractions. These images are also taken with and without microcalcifications present to study the effects of GF-estimation on microcalcification detection. We then applied the algorithm to a few clinical DICOM images with and without microcalcifications. Results: For the TOPAS simulated images, the glandular fraction was estimated with a root mean squared error of 3.2% and 2.5% for the without and with anti-scatter grid cases. Results from DICOM clinical images (where the proper glandular fraction is unknown) show that the algorithm gives a glandular fraction within the average range expected from the literature. For microcalcification detection, the contrast-to-noise ratio improved by 17.5-548% in DICOM images and 5.1-88% in TOPAS images. Significance: This work studied the accuracy of maximum likelihood estimation for a glandular fraction on simulated and clinical images and shows an improvement in contrast to noise ratio for detecting microcalcifications, a risk factor in breast cancer.Comment: Manuscipt under peer-revie

    Bleach Imaged Plasmon Propagation (BlIPP) of Metallic Nanoparticle Waveguides

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    The high speed transfer of information in materials with dimensions below the sub-diffraction limit is essential for future technological developments. Metallic nanoparticle (NP) waveguides serve a unique role in efficient energy transfer in this size regime. Light may be confined to metallic structures and propagate along the surface of the waveguide via propagating plasmon waves known as surface plasmon polaritons (SPPs). Plasmon propagation of energy in metallic structures is not perfect however and damping losses from the waveguide material lead to a characteristic exponential decay in the plasmon near field intensity. This decay length is known as the propagation length and serves as an excellent metric to compare various waveguide materials and structures to one another at particular excitation wavelengths. This thesis presents recent work in the development of a novel measurement technique termed bleach imaged plasmon propagation (BlIPP). BlIPP uses the photobleaching property of fluorophores and far field fluorescence microscopy to probe the near-field intensity of propagating plasmons and determine the propagation length. The experimental setup, image analysis, conditions, and application of BlIPP are developed within this thesis and an in depth review of the 1-photon photobleaching mechanism is also investigated. The BlIPP method is used to investigate long plasmon propagation lengths along straight chains of tightly packed Au NPs through the coupling of light to sub-radiant propagating modes, where radiative energy losses are suppressed. The findings of this work reveal, experimentally, the importance of small gap distances for the propagation of energy. Complex chain architectures are then explored using BlIPP measurements of tightly packed straight and bent chains of spherical silver NPs. We observe the highly efficient propagation of energy around sharp corners with no additional bending losses. The findings of this thesis demonstrate the advantages and capabilities of using BlIPP propagation length measurement. Further, BlIPP is used to reveal the advantage of coupling light to sub-radiant modes of NP chains, which demonstrate the ability to guide light efficiently across long distances and around complex structures, bringing us a step closer to the goal of applying plasmonic devices and circuitry in ultra compact opto-electronic devices

    Calidad de servicio y satisfacción del cliente del restaurante Amkha, Trujillo, 2022

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    El objetivo de la presente investigación es identificar la relación entre la calidad de servicio y la satisfacción del cliente del restaurante AMKHA, Trujillo, 2022, se desarrolló una investigación de tipo no experimental con diseño transversal – correlacional, tomando como muestra a 196 clientes del restaurante, se aplicó como instrumento de recolección de datos dos cuestionarios, el primero bajo el modelo SERVPERF de 22 preguntas con escala tipo Likert relacionadas a la calidad de servicio, y el segundo de 15 preguntas con escala tipo Likert según las dimensiones propuestas por Kotler y Amstrong. Luego de procesar la data recolectada se encontró que existe una relación significativa, directa y de magnitud alta entre la calidad de servicio y la satisfacción del cliente del restaurante AMKHA, Trujillo, 2022 con un coeficiente de correlación Rho de Spearman de 0.853 y un nivel de significancia de 0.000; asimismo se identificó que el nivel predominante en las percepciones de los clientes de la muestra es alto para la variable calidad de servicio (76.53%) y alto para la variable satisfacción del cliente (75%). Por tanto, se concluye que a mayor nivel de la variable calidad de servicio se obtendrá un mayor grado de satisfacción de sus clientes
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