39 research outputs found
Subsidies to Technology Adoption when Firms' Information is Endogenous
How should firms be incentivized to adopt new technologies when the technical merits and spillovers of such technologies are uncertain? We show that, when information is dispersed but exogenous, effciency can be induced with simple (constant) subsidies. When, instead, firms must also be incentivized to collect information effciently, subsidies must be conditioned on the ex-post profi tability of the new technology and, when the cost of information acquisition is unknown to the planner, on the aggregate investment in the new technology. The optimal policy has a Pigou's flavor but accounts for the non-observability of fi rms' acquisition and usage of information
Visualization of Amyloid Oligomers in the Brain of Patients with Alzheimer's Disease
In the pathogenesis of Alzheimer's disease (AD), highly neurotoxic amyloid-β (Aβ) oligomers appear early, they are thus considered to be deeply involved in the onset of Alzheimer's disease. However, Aβ oligomer visualization is challenging in human tissues due to their multiple forms (e.g., low- and high-molecular-weight oligomers, including protofibrils) as well as their tendency to rapidly change forms and aggregate. In this review, we present two visualization approaches for Aβ oligomers in tissues: an immunohistochemical (using the monoclonal antibody TxCo1 against toxic Aβ oligomer conformers) and imaging mass spectrometry using the small chemical Shiga-Y51 that specifically binds Aβ oligomers. TxCo1 immunohistochemistry revealed Aβ oligomer distributions in postmortem human brains with AD. Using Shiga-Y51, imaging mass spectrometry revealed Aβ oligomer distributions in the brain of a transgenic mouse model for AD. These two methods would potentially contribute to elucidating the pathological mechanisms underlying AD.journal articl
Association of step counts with cognitive function in apparently healthy middle-aged and older Japanese men
Background:
Increasing physical activity may prevent cognitive decline. Previous studies primarily focused on older adults and used self-reported questionnaires to assess physical activity. We examined the relationship between step count, an objective measure of physical activity, and cognitive function in community-based middle-aged and older Japanese men.
Methods:
The Shiga Epidemiological Study of Subclinical Atherosclerosis randomly recruited community-dwelling healthy men aged 40-79 years from Shiga, Japan, and measured their step counts over 7 consecutive days using a pedometer at baseline (2006-2008). Among men who returned for follow-up (2009-2014), we assessed their cognitive function using the Cognitive Abilities Screening Instrument (CASI) score. We restricted our analyses to those with valid 7-day average step counts at baseline and those who remained free of stroke at follow-up (n = 676). Using analysis of covariance, we calculated the adjusted means of the CASI score according to the quartiles of the average step counts.
Results:
The mean (standard deviation) of age and unadjusted CASI score were 63.8 (9.1) years and 90.8 (5.8), respectively. The CASI score was elevated in higher quartiles of step counts (90.2, 90.4, 90.6, and 91.8 from the lowest to the highest quartile, respectively, [p for trend = 0.004]) in a model adjusted for age and education. Further adjustment for smoking, drinking, and other cardiovascular risk factors resulted in a similar pattern of association (p for trend = 0.005).
Conclusion:
In apparently healthy middle-aged and older Japanese men, a greater 7-day average step count at baseline was associated with significantly higher cognitive function score.journal articl
Association of Arterial Stiffness and Atherosclerotic Burden With Brain Structural Changes Among Japanese Men
Background
Little is known regarding whether arterial stiffness and atherosclerotic burden are each independently associated with brain structural changes. Simultaneous assessments of both arterial stiffness and atherosclerotic burden in associations with brain could provide insights into the mechanisms of brain structural changes.
Methods and Results
Using data from the SESSA (Shiga Epidemiological Study of Subclinical Atherosclerosis), we analyzed data among 686 Japanese men (mean [SD] age, 67.9 [8.4] years; range, 46–83 years) free from history of stroke and myocardial infarction. Brachial‐ankle pulse wave velocity and coronary artery calcification on computed tomography scans were measured between March 2010 and August 2014. Brain volumes (total brain volume, gray matter, Alzheimer disease signature and prefrontal) and brain vascular damage (white matter hyperintensities) were quantified using brain magnetic resonance imaging from January 2012 through February 2015. In multivariable adjustment models including mean arterial pressure, when brachial‐ankle pulse wave velocity and coronary artery calcification were entered into the same models, the β (95% CI) for Alzheimer disease signature volume for each 1‐SD increase in brachial‐ankle pulse wave velocity was −0.33 (−0.64 to −0.02), and the unstandardized β (95% CI) for white matter hyperintensities for each 1‐unit increase in coronary artery calcification was 0.68 (0.05–1.32). Brachial‐ankle pulse wave velocity and coronary artery calcification were not statistically significantly associated with total brain and gray matter volumes.
Conclusions
Among Japanese men, higher arterial stiffness was associated with lower Alzheimer disease signature volumes, whereas higher atherosclerotic burden was associated with brain vascular damage. Arterial stiffness and atherosclerotic burden may be independently associated with brain structural changes via different pathways.journal articl
Money Growth, Dynamic Efficiency and Asset Bubbles in a Perpetual Youth Model
We consider a perpetual youth model in which real balances are an argument of the utility function. We show that dynamic efficiency is compatible with a positive inflation rate, and that the higher inflation, the larger is the size of the bubble required to remove the inefficiency
Risk-aversion, optimal leverage and the investment-uncertainty relation
We develop a partial equilibrium dynamic model in which firms are risk-averse. We analyse the determinants of the investment-uncertainty relationship by means of numerical techniques. When firms can borrow \ubfoutside\ubf resources at the riskless rate, an increase in price volatility depresses investment for realistic parameter values. In our model, portfolio considerations play an important role. When the marginal revenue of capital becomes more uncertain, the risk-averse firm\ubfs owners reduce their \ubfshort position\ubf in the risk-free asset, thus diminishing the firm\ubfs debt level. The contraction in leverage reduces the expected returns on investment because the expected marginal revenue product is higher than the user cost of capital. In turn, the reduction in expected returns tends to depress investment
Risk aversion heterogeneity and the investment-uncertainty relationship
We develop a dynamic macroeconomic model encompassing heterogeneity in households' attitudes towards risk, and we allow agents to share aggregate volatility by trading safe assets. In equilibrium, when volatility increases, low-risk-averse households, who hold a long position in risky assets, perceive a higher certainty-equivalent future return on capital. The perceived yield may also increase for high-risk-averse agents, who hold riskless assets. In response to a rise in certainty-equivalent expected returns, savings decrease due to a limited willingness to substitute consumption over time. This generates a negative response of aggregate investment to an increase in systematic volatility, showing that the aggregate behavior of an heterogeneous agents economy can be different from the behavior originating from an `average' representative agent. The appearance of degenerate wealth distributions is avoided by allowing the risk aversion of each household to change stochastically over time