578 research outputs found
Regulatory Effectiveness in The Electric Utility Industry: An Empirical Analysis
An established result in the theory of the regulated firm is that an effective rate-of-return constraint induces the firm to employ larger proportions of capital inputs to noncapital inputs than would be the case in the absence of the regulatory constraint. This overcapitalization, often referred to as the Averch-Johnson effect, has been the subject of several recent empirical studies of the electric utility industry. The present study adds to this body of literature. It seeks to test for the effectiveness of utility regulation in the context of a cost minimization model which includes the allowed rate of return as an explanatory variable and permits arbitrary elasticities of substitution for any pair of inputs
Twice Chosen: Spouse Matching and Earnings Among Women in First and Second Marriages
This study examines spousal matching for females in second-order marriages. It is based on detailed data from longitudinal Swedish population data registers. We aim to follow women who marry, divorce, and subsequently remarry compared with females who marry and stay married over the course of the study interval. The earnings of both groups are modeled through regression analysis in the year prior to their marriages along with the earnings of each husband. The residuals from the regressions represent unobservables in the process of earnings generation. From the regressions we obtain spouse-to-be pairs of earnings residuals and we measure the correlation of residuals for each marital regime. Overall, we find significant positive correlations for all three of the marital partitions. The correlation tends to be smaller for the first of a sequence of marriages for women who divorce than for women who marry and stay so. For the second of the successive marriages, however, the correlation of the residuals is larger than that for women who marry but once. We also find evidence of “matching” between successive husbands. Women who marry men with unmeasured positive earnings capacities, in the event of divorce, tend to select and match in a similar fashion the second time around.Marital matching; Remarriage; Assortative mating; Earnings
Incidence of Reported Disability among Men: Accounting for Self Selection
A large volume of research has investigated consequences of physical and health impairments with respect to labor force attachments and earnings of persons with disabilities. Many of these studies are based on data sources in which individual disability status is self-reported. Considerably less attention has been devoted to factors that determine self-reported disability. The contribution of this paper is in its distinction between two aspects of endogenous selection in the transition from self-declared nondisability to disability status. On one hand, measured earnings and income might exert a direct effect on the individual’s propensity to report disability. On the other hand, some individuals possess unmeasured traits that might simultaneously affect their earnings and their propensity to report a disability. Based on samples of individuals from the U.S. Current Population Survey at two points in time, and using individuals who initially do not report a disability, this study looks for an explicit role of earnings per se in the reporting decision. Second, it examines whether transitions to disability between the two periods occur in the presence of correlation between unmeasured factors present in both earnings during the first period and the subsequent decision to report a disability
The Feasibility of Imaging Myocardial Ischemic/Reperfusion Injury Using \u3csup\u3e99m\u3c/sup\u3eTc-labeled Duramycin in a Porcine Model
When pathologically externalized, phosphatidylethanolamine (PE) is a potential surrogate marker for detecting tissue injuries. 99mTc-labeled duramycin is a peptide-based imaging agent that binds PE with high affinity and specificity. The goal of the current study was to investigate the clearance kinetics of 99mTc-labeled duramycin in a large animal model (normal pigs) and to assess its uptake in the heart using a pig model of myocardial ischemia–reperfusion injury.
Methods
The clearance and distribution of intravenously injected 99mTc-duramycin were characterized in sham-operated animals (n = 5). In a closed chest model of myocardial ischemia, coronary occlusion was induced by balloon angioplasty (n = 9). 99mTc-duramycin (10–15 mCi) was injected intravenously at 1 hour after reperfusion. SPECT/CT was acquired at 1 and 3 hours after injection. Cardiac tissues were analyzed for changes associated with acute cellular injuries. Autoradiography and gamma counting were used to determine radioactivity uptake. For the remaining animals, 99mTc-tetrafosamin scan was performed on the second day to identify the infarct site.
Results
Intravenously injected 99mTc-duramycin cleared from circulation predominantly via the renal/urinary tract with an α-phase half-life of 3.6 ± 0.3 minutes and β-phase half-life of 179.9 ± 64.7 minutes. In control animals, the ratios between normal heart and lung were 1.76 ± 0.21, 1.66 ± 0.22, 1.50 ± 0.20 and 1.75 ± 0.31 at 0.5, 1, 2 and 3 hours post-injection, respectively. The ratios between normal heart and liver were 0.88 ± 0.13, 0.80 ± 0.13, 0.82 ± 0.19 and 0.88 ± 0.14. In vivo visualization of focal radioactivity uptake in the ischemic heart was attainable as early as 30 min post-injection. The in vivo ischemic-to-normal uptake ratios were 3.57 ± 0.74 and 3.69 ± 0.91 at 1 and 3 hours post-injection, respectively. Ischemic-to-lung ratios were 4.89 ± 0.85 and 4.93 ± 0.57; and ischemic-to-liver ratios were 2.05 ± 0.30 to 3.23 ± 0.78. The size of 99mTc-duramycin positive myocardium was qualitatively larger than the infarct size delineated by the perfusion defect in 99mTc-tetrafosmin uptake. This was consistent with findings from tissue analysis and autoradiography.
Conclusion
99mTc-duramycin was demonstrated, in a large animal model, to have suitable clearance and biodistribution profiles for imaging. The agent has an avid target uptake and a fast background clearance. It is appropriate for imaging myocardial injury induced by ischemia/reperfusion
Public Concern About Monitoring Twitter Users and Their Conversations to Recruit for Clinical Trials: Survey Study
Background:
Social networks such as Twitter offer the clinical research community a novel opportunity for engaging potential study participants based on user activity data. However, the availability of public social media data has led to new ethical challenges about respecting user privacy and the appropriateness of monitoring social media for clinical trial recruitment. Researchers have voiced the need for involving users’ perspectives in the development of ethical norms and regulations. Objective:
This study examined the attitudes and level of concern among Twitter users and nonusers about using Twitter for monitoring social media users and their conversations to recruit potential clinical trial participants. Methods:
We used two online methods for recruiting study participants: the open survey was (1) advertised on Twitter between May 23 and June 8, 2017, and (2) deployed on TurkPrime, a crowdsourcing data acquisition platform, between May 23 and June 8, 2017. Eligible participants were adults, 18 years of age or older, who lived in the United States. People with and without Twitter accounts were included in the study. Results:
While nearly half the respondents—on Twitter (94/603, 15.6%) and on TurkPrime (509/603, 84.4%)—indicated agreement that social media monitoring constitutes a form of eavesdropping that invades their privacy, over one-third disagreed and nearly 1 in 5 had no opinion. A chi-square test revealed a positive relationship between respondents’ general privacy concern and their average concern about Internet research (PP=.001) and whether they consider Twitter monitoring for clinical trial recruitment as eavesdropping (PP=.003). As Twitter literacy increased, so did people’s concerns about researchers monitoring Twitter activity. Our data support the previously suggested use of the nonexceptionalist methodology for assessing social media in research, insofar as social media-based recruitment does not need to be considered exceptional and, for most, it is considered preferable to traditional in-person interventions at physical clinics. The expressed attitudes were highly contextual, depending on factors such as the type of disease or health topic (eg, HIV/AIDS vs obesity vs smoking), the entity or person monitoring users on Twitter, and the monitored information. Conclusions:
The data and findings from this study contribute to the critical dialogue with the public about the use of social media in clinical research. The findings suggest that most users do not think that monitoring Twitter for clinical trial recruitment constitutes inappropriate surveillance or a violation of privacy. However, researchers should remain mindful that some participants might find social media monitoring problematic when connected with certain conditions or health topics. Further research should isolate factors that influence the level of concern among social media users across platforms and populations and inform the development of more clear and consistent guidelines
On selection criteria for problems with moving inhomogeneities
We study mechanical problems with multiple solutions and introduce a
thermodynamic framework to formulate two different selection criteria in terms
of macroscopic energy productions and fluxes. Studying simple examples for
lattice motion we then compare the implications for both resting and moving
inhomogeneities.Comment: revised version contains new introduction, numerical simulations of
Riemann problems, and a more detailed discussion of the causality principle;
18 pages, several figure
О работе конференции "Лекарственные средства Республики Беларусь"
ЗДРАВООХРАНЕНИЕ РЕСПУБЛИКИ БЕЛАРУСЬЛЕКАРСТВАКОНГРЕСС
The population genomic basis of geographic differentiation in North American common ragweed (<i>Ambrosia artemisiifolia</i> L.)
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