Trade Models with Heterogeneous Firms: What About Importing?

Intermediate goods make up a large share of world trade. Yet trade models with heterogeneous firms focus almost exclusively on firms’ export decisions rather than their import decisions. We develop an analytically solvable model of a small open economy in which heterogeneous firms make endogenous import decisions. We view decisions about importing as decisions about technology adoption. In our model, firms weigh the benefit of operating a technology that uses imported intermediate goods against the fixed cost of developing trade relationships with foreign input suppliers. Similar to the selection effect in standard export-decision models, only the most efficient firms choose to import. In addition, the model features a technology upgrading effect, where importing improves a firm’s labor efficiency. The calibrated model quantifies the selection and technology upgrading effects, captures the large performance advantage associated with using imported intermediate goods, and generates large increases in trade from small decreases in tariffs.hetrogenious firms, importing, Chile, fixed costs

High-resolution N-body Simulations of Galactic Cannibalism: The Magellanic Stream

Hierarchical clustering represents the favoured paradigm for galaxy formation throughout the Universe; due to its proximity, the Magellanic system offers one of the few opportunities for astrophysicists to decompose the full six-dimensional phase-space history of a satellite in the midst of being cannibalised by its host galaxy. The availability of improved observational data for the Magellanic Stream and parallel advances in computational power has led us to revisit the canonical tidal model describing the disruption of the Small Magellanic Cloud and the consequent formation of the Stream. We suggest improvements to the tidal model in light of these recent advances.Comment: 6 pages, 4 figures, LaTeX (gcdv.sty). Refereed contribution to the 5th Galactic Chemodynamics conference held in Swinburne, July 2003. Accepted for publication in PASA. Version with high resolution figures available at http://astronomy.swin.edu.au/staff/tconnors/publications.htm

Design of a scientific probe for obtaining Mars surface material

The objective is to return a 1 Kg Martian soil sample from the surface of Mars to a mothership in a 60 km Mars orbit. Given here is information on the mission profile, the structural design and component placement, thermal control and guidance, propulsion systems, orbital mechanics, and specialized structures

Trade Models with Heterogeneous Firms: What About Importing?

Intermediate goods make up a large share of world trade. Yet trade models with heterogeneous firms focus almost exclusively on firms’ export decisions rather than their import decisions. We develop an analytically solvable model of a small open economy in which heterogeneous firms make endogenous import decisions. We view decisions about importing as decisions about technology adoption. In our model, firms weigh the benefit of operating a technology that uses imported intermediate goods against the fixed cost of developing trade relationships with foreign input suppliers. Similar to the selection effect in standard export-decision models, only the most efficient firms choose to import. In addition, the model features a technology upgrading effect, where importing improves a firm’s labor efficiency. The calibrated model quantifies the selection and technology upgrading effects, captures the large performance advantage associated with using imported intermediate goods, and generates large increases in trade from small decreases in tariffs

Differentiation of Agaricus species and other homobasidiomycetes based on volatile production patterns using an electronic nose system

Comparisons of the qualitative volatile production patterns between seven species of Agaricus, and between two of Volvariella and Pleurotus and one Coprinus species when grown at 25°C on agar media for 14d were made. There was good reproducibility between the volatile production patterns of the same species using an electronic nose unit with a 14 conducting sensor polymer array. Principle Component Analysis (PCA) showed that it was possible to discriminate between five of the seven Agaricus species, but that some overlap occurred between the others. Cluster analysis showed that there was also overlap between some species with the tropical collection of A. bitorquis separating out from the others. The volatile production profile of the commercial A. bisporus was close to that of a wild species, A. campestris. A. bisporus could be readily differentiated from other non-Agaricus species. This study demonstrates the potential for using electronic nose systems to rapidly differentiate mycelial cultures of homobasidiomycete mushrooms

Determination of output factor for CyberKnife using scintillation dosimetry and deep learning

Objective. Small-field dosimetry is an ongoing challenge in radiotherapy quality assurance (QA) especially for radiosurgery systems such as CyberKnife TM. The objective of this work is to demonstrate the use of a plastic scintillator imaged with a commercial camera to measure the output factor of a CyberKnife system. The output factor describes the dose on the central axis as a function of collimator size, and is a fundamental part of CyberKnife QA and integral to the data used in the treatment planning system. Approach. A self-contained device consisting of a solid plastic scintillator and a camera was build in a portable Pelicase. Photographs were analysed using classical methods and with convolutional neural networks (CNN) to predict beam parameters which were then compared to measurements. Main results. Initial results using classical image processing to determine standard QA parameters such as percentage depth dose (PDD) were unsuccessful, with 34% of points failing to meet the Gamma criterion (which measures the distance between corresponding points and the relative difference in dose) of 2 mm/2%. However, when images were processed using a CNN trained on simulated data and a green scintillator sheet, 92% of PDD curves agreed with measurements with a microdiamond detector to within 2 mm/2% and 78% to 1%/1 mm. The mean difference between the output factors measured using this system and a microdiamond detector was 1.1%. Confidence in the results was enhanced by using the algorithm to predict the known collimator sizes from the photographs which it was able to do with an accuracy of less than 1 mm. Significance. With refinement, a full output factor curve could be measured in less than an hour, offering a new approach for rapid, convenient small-field dosimetry. </p

Correction of Dropped Frames in High-resolution Push-broom Hyperspectral Images for Cultural Heritage

Dropped frames can occur in line-scan cameras, which result in non-uniform spatial sampling of the scene. A dropped frame occurs when data from an image sensor is not successfully recorded. When mosaicking multiple line-scan images, such as in high-resolution imaging, this can cause misalignment. Much previous work to identify dropped frames in video prioritises fast computation over high accuracy, whereas in heritage imaging, high accuracy is often preferred over short computation time. Two approaches to identify the position of dropped frames are presented, both using the A* search algorithm to correct dropped frames. One method aligns overlapping sections of push-broom images and the other aligns the push-broom image to a lower resolution reference image. The two methods are compared across a range of test images, and the method aligning overlapping sections is shown to perform better than the method using a reference image under most circumstances. The overlap method was applied to hyperspectral images acquired of La Ghirlandata, an 1873 oil on canvas painting by D. G. Rossetti, enabling a high-resolution hyperspectral image mosaic to be produced. The resulting composite image is 10,875 $\times$ 14,697 pixels each with 500 spectral bands from 400–2,500 nm. This corresponds to a spatial resolution of 80 \,\mathrm{\upmu }\mathrm{m} and a spectral resolution of 3–6 nm

Multiphoton Microscopy for Ophthalmic Imaging

We review multiphoton microscopy (MPM) including two-photon autofluorescence (2PAF), second harmonic generation (SHG), third harmonic generation (THG), fluorescence lifetime (FLIM), and coherent anti-Stokes Raman Scattering (CARS) with relevance to clinical applications in ophthalmology. The different imaging modalities are discussed highlighting the particular strength that each has for functional tissue imaging. MPM is compared with current clinical ophthalmological imaging techniques such as reflectance confocal microscopy, optical coherence tomography, and fluorescence imaging. In addition, we discuss the future prospects for MPM in disease detection and clinical monitoring of disease progression, understanding fundamental disease mechanisms, and real-time monitoring of drug delivery