Frank Springer and New Mexico: From the Colfax County War to the Emergence of Modern Santa Fe

Review of: "Frank Springer and New Mexico: From the Colfax County War to the Emergence of Modern Santa Fe," by David L. Caffey

Turbulent Chemical Diffusion in Convectively Bounded Carbon Flames

It has been proposed that mixing induced by convective overshoot can disrupt the inward propagation of carbon deflagrations in super-asymptotic giant branch stars. To test this theory, we study an idealized model of convectively bounded carbon flames with 3D hydrodynamic simulations of the Boussinesq equations using the pseudospectral code Dedalus. Because the flame propagation timescale is much longer than the convection timescale, we approximate the flame as fixed in space, and only consider its effects on the buoyancy of the fluid. By evolving a passive scalar field, we derive a {\it turbulent} chemical diffusivity produced by the convection as a function of height, $D_{\rm t}(z)$. Convection can stall a flame if the chemical mixing timescale, set by the turbulent chemical diffusivity, $D_{\rm t}$, is shorter than the flame propagation timescale, set by the thermal diffusivity, $\kappa$, i.e., when $D_{\rm t}>\kappa$. However, we find $D_{\rm t}<\kappa$ for most of the flame because convective plumes are not dense enough to penetrate into the flame. Extrapolating to realistic stellar conditions, this implies that convective mixing cannot stall a carbon flame and that "hybrid carbon-oxygen-neon" white dwarfs are not a typical product of stellar evolution.Comment: Accepted to Ap

Cognitive Constraints on Valuing Annuities

This paper documents consumers’ difficulty valuing life annuities. Using a purpose-built experiment in the American Life Panel, we show that the prices at which people are willing to buy annuities are substantially below the prices at which they are willing to sell them. We also find that buy values are negatively correlated with sell values and that the sell–buy valuation spread is negatively correlated with cognition. This spread is larger for those with less education, weaker numerical abilities, and lower levels of financial literacy. Our evidence contributes to the emerging literature on heterogeneity in financial decision-making abilities, particularly regarding retirement payouts

Behavioral Impediments to Valuing Annuities: Complexity and Choice Bracketing

This paper examines two behavioral factors that diminish people’s ability to value a lifetime income stream or annuity, drawing on a survey of about 4,000 adults in a U.S. nationally representative sample. By experimentally varying the degree of complexity, we provide the first causal evidence that increasing the complexity of the annuity choice reduces respondents’ ability to value the annuity, measured by the difference between the sell and buy values people assign to the annuity. We also find that people’s ability to value an annuity increases when we experimentally induce them to think jointly about the annuitization decision as well as how quickly or slowly to spend down assets in retirement. Accordingly, we conclude that narrow choice bracketing is an impediment to annuitization, yet this impediment can be mitigated with a relatively straightforward intervention

Corticospinal Motor Neurons and Related Subcerebral Projection Neurons Undergo Early and Specific Neurodegeneration in hSOD1G93AhSOD1^{G93A} Transgenic ALS Mice

Amyotrophic lateral sclerosis (ALS) is characterized by predominant vulnerability and central degeneration of both corticospinal/corticobulbar motor neurons (CSMN; “upper motor neurons”) in cerebral cortex, and spinal/bulbar motor neurons (SMN; “lower motor neurons”) in spinal cord and brainstem. Increasing evidence indicates broader cerebral cortex pathology in cognitive, sensory, and association systems in select cases. It remains unclear whether widely accepted transgenic ALS models, in particular $hSOD1^{G93A}$ mice, undergo degeneration of CSMN and molecularly/developmentally closely related populations of nonmotor projection neurons [e.g., other subcerebral projection neurons (SCPN)], and whether potential CSMN/SCPN degeneration is specific and early. This relative lack of knowledge regarding upper motor neuron pathology in these ALS model mice has hindered both molecular-pathophysiologic understanding of ALS and their use toward potential CSMN therapeutic approaches. Here, using a combination of anatomic, cellular, transgenic labeling, and newly available neuronal subtype-specific molecular analyses, we identify that CSMN and related nonmotor SCPN specifically and progressively degenerate in $hSOD1^{G93A}$ mice. Degeneration starts quite early and presymptomatically, by postnatal day 30. Other neocortical layers, cortical interneurons, and other projection neuron populations, even within layer V, are not similarly affected. Nonneuronal pathology in neocortex (activated astroglia and microglia) is consistent with findings in human ALS cortex and in affected mouse and human spinal cord. These results indicate previously unknown neuron type-specific vulnerability of CSMN/sensory and association SCPN, and identify that characteristic dual CSMN and SMN degeneration is conserved in $hSOD1^{G93A}$ mice. These results provide a foundation for detailed investigation of CSMN/SCPN vulnerability and toward potential CSMN therapeutics in ALS.Stem Cell and Regenerative Biolog