3,249 research outputs found
Innovation Through Protection: Does Safeguard Protection Increase Investment in R and D?
We perform the first empirical study to focus on the relationship between trade protection and investment in Research and Development. Our results support predictions from the theoretical literature that temporary tariffs stimulate research and development, although we find no evidence that this effect diminishes as the termination of protection approaches as predicted by some theoretical models. We also find little evidence that quotas reduce research and development as predicted by multiple theoretical works. Finally, our results indicate that temporary tariffs result in decreased capital investment, perhaps because firms use periods of temporary protection to shutdown unprofitable facilities. This reveals an important distinction in firm behavior with regard to investment in tangible versus intangible capital during periods of trade protection.Research and Development, Strategic Protection
Echoes of Daniel in 1 and 2 Thessalonians
Over the last few decades there has been a growing interest regarding the use of the Hebrew Scriptures in the New Testament. One of the most frequently referenced books in the New Testament is the book of Daniel. However, the significance of Daniel as an influential source for the New Testament writers in general, and the apostle Paul in particular, has yet to be fully explored. Recognising this, the aims of the present study were to: 1) offer a methodological approach for identifying if and where Paul alludes to or echoes Daniel in 1 and 2 Thessalonians; 2) examine the effect these references have in their new context; and 3) explore how they inform us about Paul’s understanding of Daniel. vi Six potential references to Daniel were evaluated: four in 1 Thessalonians and two in 2 Thessalonians. Three of these were classified as probable (Dan 12:2 in 1 Thess 4:13-15; 5:10; Dan 7:13 in 1 Thess 4:17; Dan 11:31, 36 in 2 Thess 2:3-4) and three were classified as possible (Dan 8:23 in 1 Thess 2:16; Dan 2:21 in 1 Thess 5:1; Dan 7:9-10, 27 in 2 Thess 1:5-10). An examination of each of these references led us to conclude that: first, similarities with sayings of Jesus indicate that Paul had most likely re-read Daniel through the lens of the gospel tradition; second, Paul was not drawing on themes and passages that were disconnected from each other, but were part of the same apocalyptic narrative that had proved a source of comfort to many generations of believers in the midst of persecution; and third, as part of that, he understood himself and the believers to be living within that narrative, as indicated by his interpretation of the enemy of God’s people in Daniel 11:40-45 as still being future
Ionization, Kinematics, and Extent of the Diffuse Ionized Gas Halo of NGC 5775
We present key results from deep spectra of the Diffuse Ionized Gas (DIG)
halo of the edge-on galaxy NGC 5775. [NII]6583 has been detected up to about
z=13 kpc above the plane in one of two vertically oriented long slits -- making
this the spiral galaxy with the greatest spectroscopically detected halo extent
in emission. Key diagnostic line ratios have been measured up to about z=8 kpc,
allowing the source of ionization and physical state to be probed. Ionization
by a dilute radiation field from massive stars in the disk can explain some of
the line ratio behavior, but departures from this picture are clearly
indicated, most strongly by the rise of [OIII]/Halpha with z. Velocities of the
gas in both slits approach the systemic velocity of the galaxy at several kpc
above the plane. We interpret this trend as a decrease in rotation velocity
with z, with essentially no rotation at heights of several kpc. Such a trend
was observed in the edge-on galaxy NGC 891, but here much more dramatically.
This falloff is presumably due to the gravitational potential changing with z,
but will also depend on the hydrodynamic nature of the disk-halo cycling of gas
and projection effects. More detailed modeling of the ionization and kinematics
of this and other edge-ons will be presented in future papers.Comment: figures 1, 2a-d and 3 included. ApJ Letters, in pres
The Impact of Continuous Versus Intermittent Physical Activity on Vascular Function While Sitting
Previous studies demonstrate prolonged sitting impairs blood vessel function. However, these studies also demonstrate breaking up sitting time by exercise maintains endothelial function. No one has examined whether a continuous bout of exercise prior to sitting is as effective as breaks in sitting on maintaining endothelial function. PURPOSE: This study examined whether continuous versus intermittent bouts of exercise are more effective at maintaining vascular health while sitting. METHODS: 5 males (age: 36±18, BMI: 22±5) and 1 female participated in three randomized 3-hour sitting trials where popliteal endothelial function was measured via Doppler ultrasound every hour. In the sedentary trial (SED), subjects sat for 3 continuous hours with their leg in a 90° bend. In the continuous exercise trial (CON), the subjects walked for 30-minutes at 2-mph on a treadmill before sitting for 3-hours. During the intermittent exercise trial (INT), subjects sat for 3 hours similar to the SED condition; however, every 30-minutes they walked at 2-mph for 5-minutes. Flow-mediated dilation (FMD) was performed at baseline, 1-hr, 2-hr, and 3-hr in each trial. RESULTS: Percent change in FMD was unaltered between groups or across each trial (p\u3e0.05). CONCLUSIONS: These preliminary data suggest that endothelial function is unaltered across the groups. This is an ongoing study and we are actively recruiting more individuals to increase the power of this study due to our low sample size.https://digitalcommons.odu.edu/education_darden/1004/thumbnail.jp
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Quality and Publication of Emergency Medicine Trials Registered in ClinicalTrials.gov
Introduction: Promoting emergency medicine (EM) clinical trials research remains a priority. To characterize the status of clinical EM research, this study assessed trial quality, funding source, and publication of EM clinical trials and compared EM and non-EM trials on these key metrics. We also examined the volume of EM trials and their subspecialty areas.Methods: We abstracted data from ClinicalTrials.gov (February 2000 - September 2013) and used individual study National Clinical Trial numbers to identify published trials (January 2007 - September 2016). We used descriptive statistics and chi-square tests to examine study characteristics by EM and non-EM status, and Kaplan-Meier curves and log-rank tests to compare time to publication of completed EM and non-EM studies.Results: We found 638 interventional EM trials and 59,512 non-EM interventional trials conducted in the United States between February 2000 and September 2013, registered on ClinicalTrials.gov. EM studies were significantly less likely than non-EM studies to be National Institutes of Health-funded or to evaluate a drug or biologic. However, EM studies had significantly larger sample sizes, and were significantly more likely to use randomization and blinding. Overall, 34.3% of EM and 26.0% of non-EM studies were published in peer-reviewed journals. By subspecialty, more EM trials concerned medical/surgical and psychiatric/neurological conditions than trauma.Conclusion: Although EM studies were less likely to have received federal or industry funding, and the EM portfolio consisted of only 638 trials over the 14-year study period, the quality of EM trials surpassed that of non-EM trials, based on indices such as randomization and blinding. This novel finding bodes well for the future of clinical EM research, as does the higher proportion of published EM than non-EM trials. Our study also revealed that trauma studies were under-represented among EM studies. Periodic assessment of EM trials with the metrics used here could provide an informative and valuable longitudinal view of progress in clinical EM research
Lightweight Aggregate as Internal Curing Agent to Limit Concrete Skrinkage
The effectiveness of prewetted, vacuum saturated (PVS) lightweight aggregate (LWA) as an internal curing agent to reduce concrete shrinkage is evaluated for curing periods of 7 and 14 days. Normalweight aggregate is replaced by LWA at volume replacement levels ranging from 8.9 to 13.8%. Some mixtures contain a partial replacement of portland cement with slag cement while maintaining the paste content at approximately 24.1% of concrete volume. Comparisons are made with mixtures containing low-absorption granite and high-absorption limestone normalweight coarse aggregates. At the replacement levels used in this study, PVS LWA results in a small reduction in concrete density, no appreciable effect on concrete compressive strength, and a substantial decrease in concrete shrinkage for drying periods up to 365 days. Increasing the curing period from 7 to 14 days reduces concrete shrinkage. Thirty and 60% volume replacements of portland cement by slag cement result in reduced shrinkage when used with a porous LWA or normalweight aggregate. After 30 and 365 days of drying, all mixtures with LWA exhibited less shrinkage than the mixtures with either low- or high-absorption normalweight aggregates
Lightweight Aggregate as Internal Curing Agent to Limit Concrete Shrinkage
The effectiveness of prewetted, vacuum-saturated (PVS) lightweight aggregate (LWA) as an internal curing agent to reduce concrete shrinkage is evaluated for curing periods of 7 and 14 days. Normalweight aggregate is replaced by LWA at volume replacement levels ranging from 8.9 to 13.8%. Some mixtures contain a partial replacement of portland cement with slag cement while maintaining the paste content at approximately 24.1% of concrete volume. Comparisons are made with mixtures containing low-absorption granite and high absorption limestone normalweight coarse aggregates. At the replacement levels used in this study, PVS LWA results in a small reduction in concrete density, no appreciable effect on concrete compressive strength, and a
substantial decrease in concrete shrinkage for drying periods up to 365 days. Increasing the curing period from 7 to 14 days reduces concrete shrinkage. Thirty and 60% volume replacements of portland cement by slag cement result in reduced shrinkage when used with a porous LWA or normalweight aggregate. After
30 and 365 days of drying, all mixtures with LWA exhibited less shrinkage than the mixtures with either low- or high-absorption normalweight aggregates
Mathematical models of the roles of IL-2 and IL-7 in T cell homeostasis
We study the homeostasis of a peripheral naive T cell population through the use of deterministic mathematical models. A two compartment approach is used, where, naive T cells are assumed to be either in a resting state, or undergoing the cell cycle. We begin by assuming all rates are linear, then discuss the limitations in doing so. We next explore examples of published methods which improve this simple description. Finally, we introduce a model in which resting T cell survival and entry into the cell
cycle is assumed to be dependent on the amount of available IL-7.
To aid our description of T cell homeostasis, a stochastic model of IL-7 signalling is developed. In this model we consider the number of IL-7 receptors, either membrane bound or internalised, the extra-cellular
concentration of IL-7, and the amount of IL-7 induced signalling. The model is used to derive a relationship between the amount of IL-7 induced signalling to the extra-cellular concentration of IL-7. The survival and proliferative ability of the T cell population is then assumed to be dependent on the amount of IL-7 induced signalling with respect to IL-7 signalling thresholds for survival and division.
This signalling relation is then used with the model of T cell homeostasis. The model is fitted to experimental data measuring the expansion of transgenic naive T cells in lymphopenic mice. We show this approach can capture the homeostatic equilibrium, and notably, time scales required
to reach equilibrium. The model is then explored in the context of the human periphery.
In a separate piece of work we develop a stochastic Markov model of the peripheral CD4+ T cell pool, in which we consider sub-populations of naive, IL-2 producing, IL-2 non-producing and regulatory T cells. The balance between the IL-2 producing and regulatory sub-populations
is assumed to be determined by a recently proposed quorum-sensing hypothesis. This model is explored in scenarios where no antigen is presented to the CD4+ population, before and after a challenge, and when antigen is presented at a constant level. We show, amongst other results, that the number of regulatory T cells in equilibrium is greater
when antigen is presented, whilst the number of IL-2 producing T cells remains the same. We finally use the stochastic aspect of this model to explore probabilities of and times to extinction of the sub-populations
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