1,273 research outputs found
The Effect of Medical Marijuana Laws on the Labor Supply of Older Adults: Evidence from the Health and Retirement Study
We study the effect of state medical marijuana laws on labor supply among older adults; the demographic group with the highest rates of many health conditions for which marijuana may be an effective treatment. We use the Health and Retirement Study to study this question and estimate differences-in-differences regression models. We find that passage of a state medical marijuana law leads to increases in labor supply among older adults. These effects should be considered as policymakers determine how best to regulate access to medical marijuana
Propellant Vaporization as a Criterion for Rocket-Engine Design; Experimental Performance, Vaporization and Heat-Transfer Rates with Various Propellant Combinations
Experimental combustion efficiencies of eleven propellant combinations were determined as a function of chamber length. Efficiencies were measured in terms of characteristic exhaust velocities at three chamber lengths and in terms of gas velocities. The data were obtained in a nominal 200-pound-thrust rocket engine. Injector and engine configurations were kept essentially the same to allow comparison of the performance. The data, except for those on hydrazine and ammonia-fluorine, agreed with predicted results based on the assumption that vaporization of the propellants determines the rate of combustion. Decomposition in the liquid phase may be.responsible for the anomalous behavior of hydrazine. Over-all heat-transfer rates were also measured for each combination. These rates were close to the values predicted by standard heat-transfer calculations except for the combinations using ammonia
Influence of diffraction on the spectrum and wavefunctions of an open system
In this paper, we demonstrate the existence and significance of diffractive
orbits in an open microwave billiard, both experimentally and theoretically.
Orbits that diffract off of a sharp edge of the system are found to have a
strong influence on the transmission spectrum of the system, especially in the
regime where there are no stable classical orbits. On resonance, the
wavefunctions are influenced by both classical and diffractive orbits. Off
resonance, the wavefunctions are determined by the constructive interference of
multiple transient, nonperiodic orbits. Experimental, numerical, and
semiclassical results are presented.Comment: 27 pages, 29 figures, and 3 tables. Submitted to Physical Review E. A
copy with higher resolution figures is available at
http://monsoon.harvard.edu/~hersch/papers.htm
Information on 'overdiagnosis' in breast cancer screening on prominent United Kingdom- and Australia-oriented health websites
Objectives: Health-related websites are an important source of information for the public. Increasing public awareness of overdiagnosis and ductal carcinoma in situ (DCIS) in breast cancer screening may facilitate more informed decision-making. This study assessed the extent to which such information was included on prominent health websites oriented towards the general public, and evaluated how it was explained. Design: Cross-sectional study. Setting: Websites identified through Google searches in England (United Kingdom) and New South Wales (Australia) for “breast cancer screening” and further websites included based on our prior knowledge of relevant organisations. Main outcomes: Content analysis was used to determine whether information on overdiagnosis or DCIS existed on each site, how the concepts were described, and what statistics were used to quantify overdiagnosis. Results: After exclusions, ten UK websites and eight Australian websites were considered relevant and evaluated. They originated from charities, health service providers, government agencies, and an independent health organisation. Most contained some information on overdiagnosis (and/or DCIS). Descriptive information was similar across websites. In the UK sample, statistical information was often based on estimates from the Independent UK Panel on Breast Cancer Screening; the most commonly provided statistic was the ratio of breast cancer deaths prevented to overdiagnosed cases (1:3). A range of other statistics was included, such as the yearly number of overdiagnosed cases and the proportion of women screened who would be overdiagnosed. Information on DCIS and statistical information were found less commonly on the Australian websites. Conclusions: Online information about overdiagnosis has become more widely available in 2015-16 compared with the limited accessibility indicated by older research. However, there may be scope to offer more information on DCIS and overdiagnosis statistics on Australian websites. Moreover, the variability in how estimates are presented across UK websites may be confusing for the general public
Improving communication about cancer screening: moving towards informed decision making
For decades, public communications about cancer screening have used persuasive techniques with the aim of maximising the number of people being screened. However, perspectives have changed more recently to acknowledge that screening can lead to harm as well as benefit, and that it is important for service users to consider both. For some types of cancer screening, there is professional contention about whether benefits clearly outweigh harms. In light of this, an emerging trend in cancer screening communication is to try to support informed decision making - that is, to help people understand both the advantages and disadvantages of screening, allowing them to make individual decisions about their screening participation that reflect their informed preferences. In this review, we provide an overview of key theoretical and practical aspects of improving communication and supporting informed decision making about cancer screening, highlight relevant research and discuss future implications
Maximizing Neumann fundamental tones of triangles
We prove sharp isoperimetric inequalities for Neumann eigenvalues of the
Laplacian on triangular domains.
The first nonzero Neumann eigenvalue is shown to be maximal for the
equilateral triangle among all triangles of given perimeter, and hence among
all triangles of given area. Similar results are proved for the harmonic and
arithmetic means of the first two nonzero eigenvalues
Translation Initiation Rate Determines the Impact of Ribosome Stalling on Bacterial Protein Synthesis
Ribosome stalling during translation can be caused by a number of characterized mechanisms. However, the impact of elongation stalls on protein levels is variable, and the reasons for this are often unclear. To investigate this relationship, we examined the bacterial translation elongation factor P (EF-P), which plays a critical role in rescuing ribosomes stalled at specific amino acid sequences including polyproline motifs. In previous proteomic analyses of both Salmonella and Escherichia coli efp mutants, it was evident that not all proteins containing a polyproline motif were dependent on EF-P for efficient expression in vivo . The α- and β-subunits of ATP synthase, AtpA and AtpD, are translated from the same mRNA transcript, and both contain a PPG motif; however, proteomic analysis revealed that AtpD levels are strongly dependent on EF-P, whereas AtpA levels are independent of EF-P. Using these model proteins, we systematically determined that EF-P dependence is strongly influenced by elements in the 5′-untranslated region of the mRNA. By mutating either the Shine-Dalgarno sequence or the start codon, we find that EF-P dependence correlates directly with the rate of translation initiation where strongly expressed proteins show the greatest dependence on EF-P. Our findings demonstrate that polyproline-induced stalls exert a net effect on protein levels only if they limit translation significantly more than initiation. This model can be generalized to explain why sequences that induce pauses in translation elongation to, for example, facilitate folding do not necessarily exact a penalty on the overall production of the protein
Observation of diffractive orbits in the spectrum of excited NO in a magnetic field
We investigate the experimental spectra of excited NO molecules in the
diamagnetic regime and develop a quantitative semiclassical framework to
account for the results. We show the dynamics can be interpreted in terms of
classical orbits provided that in addition to the geometric orbits, diffractive
effects are appropriately taken into account. We also show how individual
orbits can be extracted from the experimental signal and use this procedure to
reveal the first experimental manifestation of inelastic diffractive orbits.Comment: 4 fig
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