2,836 research outputs found
Quantitative spatial economics
The observed uneven distribution of economic activity across space is influenced by variation in exogenous geographical characteristics and endogenous interactions between agents in goods and factor markets. Until recently, the theoretical literature on economic geography had focused on stylized settings that could not easily be taken to the data. This paper reviews more recent research that has developed quantitative models of economic geography. These models are rich enough to speak to first-order features of the data, such as many heterogenous locations and gravity equation relationships for trade and commuting. Yet at the same time these models are sufficiently tractable to undertake realistic counterfactuals exercises to study the effect of changes in amenities, productivity, and public policy interventions such as transport infrastructure investments. We provide an extensive taxonomy of the different building blocks of these quantitative spatial models and discuss their main properties and quantification
Commuting, migration and local employment elasticities
Many changes in the economic environment are local, including policy changes and infrastructure investments. The effect of these changes depends crucially on the ability of factors to move in response. Therefore a key object of interest for policy evaluation and design is the elasticity of local employment to these changes in the economic environment. We develop a quantitative general equilibrium model that incorporates spatial linkages between locations in goods markets (trade) and factor markets (commuting and migration). We find substantial heterogeneity across locations in local employment elasticities. We show that this heterogeneity can be well explained with theoretically motivated measures of commuting flows. Without taking into account this dependence, estimates of the local employment elasticity for one location are not generalizable to other locations. We also find that commuting flows and their importance cannot be accounted for with standard measures of size or wages at the county or commuting zone levels
The Influence of a Slow-Breathing Protocol on Heart Rate and Blood Pressure from Exercise in Moderately Trained Females
International Journal of Exercise Science 12(2): 714-725, 2019. Heart rate recovery (HRR) and blood pressure recovery (BPR) from exercise are both important indicators of health and fitness and are strongly associated with cardiovascular disease. The purpose of this study was to compare the effects of a slow-breathing technique, upright passive recovery (PASS), and active recovery (ACT) on HRR and BPR from exercise. Nine moderately trained, college-aged (20.22 ± 0.97 yrs) female participants cycled three times on an ergometer for 15 mins at 70% of their heart rate maximum (HRmax), each of which was followed by one of three 5 min recovery interventions with heart rate (HR) and blood pressure (BP) objectively measured. Each participant completed all three recovery protocols. One recovery protocol consisted of breathing at a rate of 6 breaths per minute (BRE), another involved PASS and the third was ACT at 60 RPM and 25 W. A repeated measures ANOVA revealed there was a significant effect of protocol (p= 0.00, hp2= 0.67) with HRR. BRE resulted in the fastest HRR of 69 ± 9.31 bpm (40.12%) at the end of the 5 min recovery compared to 63 ± 10.60 bpm (36.57%) and 47 ± 12.54 bpm (27.34%) for PASS and ACT, respectively. A second repeated measures ANOVA indicated there was no effect of protocol (P = 0.43), nor was there a significant interaction with time (p= 0.68), for BPR. The results indicated that BRE increased HRR after exercise more rapidly than PASS or ACT with no influence on BPR. These findings lead to future research needed to explore different breathing protocols following exercise in at-risk populations, such as individuals with cardiovascular disease
Soft wearable robots can reduce the energy cost of poststroke walking: a proof-of-concept study
Progress toward curing HIV infection with hematopoietic cell transplantation.
HIV-1 infection afflicts more than 35 million people worldwide, according to 2014 estimates from the World Health Organization. For those individuals who have access to antiretroviral therapy, these drugs can effectively suppress, but not cure, HIV-1 infection. Indeed, the only documented case for an HIV/AIDS cure was a patient with HIV-1 and acute myeloid leukemia who received allogeneic hematopoietic cell transplantation (HCT) from a graft that carried the HIV-resistant CCR5-∆32/∆32 mutation. Other attempts to establish a cure for HIV/AIDS using HCT in patients with HIV-1 and malignancy have yielded mixed results, as encouraging evidence for virus eradication in a few cases has been offset by poor clinical outcomes due to the underlying cancer or other complications. Such clinical strategies have relied on HIV-resistant hematopoietic stem and progenitor cells that harbor the natural CCR5-∆32/∆32 mutation or that have been genetically modified for HIV-resistance. Nevertheless, HCT with HIV-resistant cord blood remains a promising option, particularly with inventories of CCR5-∆32/∆32 units or with genetically modified, human leukocyte antigen-matched cord blood
IBIS/PICsIT in-flight performances
PICsIT (Pixellated Imaging CaeSium Iodide Telescope) is the high energy
detector of the IBIS telescope on-board the INTEGRAL satellite. PICsIT operates
in the gamma-ray energy range between 175 keV and 10 MeV, with a typical energy
resolution of 10% at 1 MeV, and an angular resolution of 12 arcmin within a
\~100 square degree field of view, with the possibility to locate intense point
sources in the MeV region at the few arcmin level. PICsIT is based upon a
modular array of 4096 independent CsI(Tl) pixels, ~0.70 cm^2 in cross-section
and 3 cm thick. In this work, the PICsIT on-board data handling and science
operative modes are described. This work presents the in-flight performances in
terms of background count spectra, sensitivity limit, and imaging capabilities.Comment: 8 pages, 4 figures. Accepted for publication on A&A, special issue on
First Science with INTEGRA
Combining spectral induced polarization with x-ray tomography to investigate the importance of DNAPL geometry in sand samples
Whilst many studies have been performed to investigate the spectral induced polarization (SIP) response of Non-aqueous Phase Liquid (NAPL) contaminated soil samples there are still many uncertainties in the interpretation of the data. A key issue is that altered pore space geometries due to the presence of a NAPL phase will change the measured IP spectra. However, without any information on the NAPL distribution in the pore space, assumptions are necessary for the SIP data interpretation. Therefore, experimental data of SIP signals directly associated with different NAPL distributions is needed. We use high-resolution x-ray tomography and 3D image processing to quantitatively assess NAPL distributions in samples of fine-grained sand containing different concentrations of tetrachloroethylene (PCE) and link this to SIP measurements on the same samples. The total concentration of the sample constituents as well as the volumes of the individual NAPL blobs were calculated and used for the interpretation of the associated SIP responses. The x-ray tomography and image analysis showed that the real sample properties (porosity and NAPL distributions) differed from the targeted ones. Both contaminated samples contained less NAPL than expected from the manual sample preparation. The SIP results showed higher real conductivity and lower imaginary conductivity in the contaminated samples compared to a clean sample. This is interpreted as an effect of increased surface conductivity along interconnected NAPL blobs and decreased surface areas in the samples due to NAPL blobs larger than and enclosing grains. We conclude that the combination of SIP, x-ray tomography and image analysis is a very promising approach to achieve a better understanding of the measured SIP responses of NAPL contaminated samples
Detection of Ly\beta auto-correlations and Ly\alpha-Ly\beta cross-correlations in BOSS Data Release 9
The Lyman- forest refers to a region in the spectra of distant quasars
that lies between the rest-frame Lyman- and Lyman- emissions.
The forest in this region is dominated by a combination of absorption due to
resonant Ly and Ly scattering. When considering the 1D Ly
forest in addition to the 1D Ly forest, the full statistical
description of the data requires four 1D power spectra: Ly and
Ly auto-power spectra and the Ly-Ly real and imaginary
cross-power spectra. We describe how these can be measured using an optimal
quadratic estimator that naturally disentangles Ly and Ly
contributions. Using a sample of approximately 60,000 quasar sight-lines from
the BOSS Data Release 9, we make the measurement of the one-dimensional power
spectrum of fluctuations due to the Ly resonant scattering. While we
have not corrected our measurements for resolution damping of the power and
other systematic effects carefully enough to use them for cosmological
constraints, we can robustly conclude the following: i) Ly power
spectrum and Ly-Ly cross spectra are detected with high
statistical significance; ii) the cross-correlation coefficient is
on large scales; iii) the Ly measurements are contaminated by the
associated OVI absorption, which is analogous to the SiIII contamination of the
Ly forest. Measurements of the Ly forest will allow extension of
the usable path-length for the Ly measurements while allowing a better
understanding of the physics of intergalactic medium and thus more robust
cosmological constraints.Comment: 26 pages, 10 figures; matches version accepted by JCA
Anti-Hyperon Enhancement through Baryon Junction Loops
The baryon junction exchange mechanism recently proposed to explain valence
baryon number transport in nuclear collisions is extended to study midrapidity
anti-hyperon production. Baryon junction-anti-junction (J anti-J) loops are
shown to enhance anti-Lambda, anti-Xi, anti-Omega yields as well as lead to
long range rapidity correlations. Results are compared to recent WA97 Pb + Pb
-> Y + anti-Y + X data.Comment: 10 pages, 4 figure
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