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Helium or neopentane can be used as surrogate gas fill for deuterium (D2) or deuterium-tritium (DT) in laser-plasma interaction studies. Surrogates are convenient to avoid flammability hazards or the integration of cryogenics in an experiment. To test the degree of equivalency between deuterium and helium, experiments were conducted in the Pecos target chamber at Sandia National Laboratories. Observables such as laser propagation and signatures of laser-plasma instabilities (LPI) were recorded for multiple laser and target configurations. It was found that some observables can differ significantly despite the apparent similarity of the gases with respect to molecular charge and weight. While a qualitative behaviour of the interaction may very well be studied by finding a suitable compromise of laser absorption, electron density, and LPI cross sections, a quantitative investigation of expected values for deuterium fills at high laser intensities is not likely to succeed with surrogate gases.
Early identification of individuals at risk for dementia provides an opportunity for risk reduction strategies. Many older adults (30-60%) report specific subjective cognitive complaints, which has also been shown to increase risk for dementia. The purpose of this study is to identify whether there are particular types of complaints that are associated with future: 1) progression from a clinical diagnosis of normal to impairment (either Mild Cognitive impairment or dementia) and 2) longitudinal cognitive decline.
Participants and Methods:
415 cognitively normal older adults were monitored annually for an average of 5 years. Subjective cognitive complaints were measured using the Everyday Cognition Scales (ECog) across multiple cognitive domains (memory, language, visuospatial abilities, planning, organization and divided attention). Cox proportional hazards models were used to assess associations between self-reported ECog items at baseline and progression to impairment. A total of 114 individuals progressed to impairment over an average of 4.9 years (SD=3.4 years, range=0.8-13.8). A subset of individuals (n=352) underwent repeat cognitive assessments for an average of 5.3 years. Mixed effects models with random intercepts and slopes were used to assess associations between baseline ECog items and change in episodic memory or executive function on the Spanish and English Neuropsychological Assessment Scales. Time in years since baseline, the ECog items, and the interaction were key terms of interest in the models. Separate models for both the progression analyses and mixed effects models were fit for each ECog item that included age at the baseline visit, gender, and years of education as covariates.
Results:
More complaints on five of the eight memory items, three of the nine language items, one of the seven visuospatial items, two of the five planning items, and one of the six organization items were associated with progression to impairment (HR=1.25 to 1.59, ps=0.003 to 0.03). No items from the divided attention domain were significantly associated with progression to impairment. In individuals reporting no difficulty on ECog items at the baseline visit there was no significant change over time in episodic memory(p>0.4). More complaints on seven of the eight memory items, two of the nine language items, and three of the seven visuospatial items were associated with more decline in episodic memory (ps=0.003 to 0.04). No items from the planning, organization, or divided attention domains were significantly associated with episodic memory decline. Among those reporting no difficulty on ECog items at the baseline visit there was slight decline in executive function (ps=<0.001 to 0.06). More complaints on three of the eight memory items and three of the nine language items were associated with decline in executive function (ps=0.002 to 0.047). No items from the visuospatial, planning, organization, or divided attention domains were significantly associated with decline in executive function.
Conclusions:
These findings suggest that, among cognitively normal older adults at baseline, specific complaints across several cognitive domains are associated with progression to impairment. Complaints in the domains of memory and language are associated with decline in both episodic memory and executive function.
An intepretation of Leo Strausss chapter on The Prince in Thoughts on Machiavelli. Strausss main intent is to show his students how to understand an esoteric work.
Machiavelli cannot accomplish conversion of the world by himself. He has to convince future philosophers to follow or obey him. This is his succession problem.
An interpretation of Machiavellis play Mandragola, showing that the most ridiculous figure in the play is also its master conspirator, and represents Machiavelli himself.
Machiavelli creates the modern world of necessities that can be understood and controlled. He invented a world in the modern sense of a whole by itself, not explained by ideas or essences, and not followed by the next world.