Stock and Bond Returns with Moody Investors

We present a tractable, linear model for the simultaneous pricing of stock and bond returns that incorporates stochastic risk aversion. In this model, analytic solutions for endogenous stock and bond prices and returns are readily calculated. After estimating the parameters of the model by the general method of moments, we investigate a series of classic puzzles of the empirical asset pricing literature. In particular, our model is shown to jointly accommodate the mean and volatility of equity and long term bond risk premia as well as salient features of the nominal short rate, the dividend yield, and the term spread. Also, the model matches the evidence for predictability of excess stock and bond returns. However, the stock-bond return correlation implied by the model is somewhat higher than in the data.

Quantitative modeling of \textit{in situ} x-ray reflectivity during organic molecule thin film growth

Synchrotron-based x-ray reflectivity is increasingly employed as an \textit{in situ} probe of surface morphology during thin film growth, but complete interpretation of the results requires modeling the growth process. Many models have been developed and employed for this purpose, yet no detailed, comparative studies of their scope and accuracy exists in the literature. Using experimental data obtained from hyperthermal deposition of pentane and diindenoperylene (DIP) on SiO$_2$, we compare and contrast three such models, both with each other and with detailed characterization of the surface morphology using ex-situ atomic force microscopy (AFM). These two systems each exhibit particular phenomena of broader interest: pentacene/SiO$_2$ exhibits a rapid transition from rough to smooth growth. DIP/SiO$_2$, under the conditions employed here, exhibits growth rate acceleration due to a different sticking probability between the substrate and film. In general, \textit{independent of which model is used}, we find good agreement between the surface morphology obtained from fits to the \insitu x-ray data with the actual morphology at early times. This agreement deteriorates at later time, once the root-mean squared (rms) film roughness exceeds about 1 ML. A second observation is that, because layer coverages are under-determined by the evolution of a single point on the reflectivity curve, we find that the best fits to reflectivity data --- corresponding to the lowest values of $\chi_\nu^2$ --- do not necessarily yield the best agreement between simulated and measured surface morphologies. Instead, it appears critical that the model reproduce all local extrema in the data. In addition to showing that layer morphologies can be extracted from a minimal set of data, the methodology established here provides a basis for improving models of multilayer growth by comparison to real systems.Comment: 34 pages (double-spaced, including figures and references), 10 figures, 3 appendice

Patterns of Early Lake Ontogeny in Glacier Bay as Inferred from Diatom Assemblages

We studied a series of recently formed lakes along a deglaciation chronosequence in Glacier Bay National Park to examine changes in water chemistry, primary production, and biotic composition that accompany the early ontogeny of north-temperate lakes. Successional trends in these freshwater ecosystems have been explored with a two-tiered approach that includes (1) the comparison of limnological conditions among lakes of known age and in different stages of primary catchment succession, and (2) the inference of water-chemistry trends in individual sites based on fossil diatom stratigraphy. This paper emphasizes the reconstruction of limnological trends from fossil diatom assemblages. The modem distribution of diatoms in relation to water-chemistry gradients within 32 lakes of varied age is used to derive a transfer function for the reconstruction of chemical trends from fossil assemblages in sediment cores. The modem data suggest that pH and TN (total nitrogen) exert significant and independent controls on diatom distributions, and thus trends in these variables are reconstructed for Bartlett Lake, as an example of our approach. Core reconstruction corroborates patterns in pH suggested by the modem chronosequence and shows a gradual decline in lake water pH after about 100 years. The Bartlett Lake core also follows the chronosequence pattern in TN concentration, with an initial increase followed by a decline after ca. 100 years. Reconstructions from other sites, however, suggest that trends in total nitrogen concentration are variable, and thus that localized patterns of plant colonization and soil development may result in regional variability in lake water nitrogen concentration over time

Patterns of Early Lake Ontogeny in Glacier Bay as Inferred from Diatom Assemblages

We studied a series of recently formed lakes along a deglaciation chronosequence in Glacier Bay National Park to examine changes in water chemistry, primary production, and biotic composition that accompany the early ontogeny of north-temperate lakes. Successional trends in these freshwater ecosystems have been explored with a two-tiered approach that includes (1) the comparison of limnological conditions among lakes of known age and in different stages of primary catchment succession, and (2) the inference of water-chemistry trends in individual sites based on fossil diatom stratigraphy. This paper emphasizes the reconstruction of limnological trends from fossil diatom assemblages. The modem distribution of diatoms in relation to water-chemistry gradients within 32 lakes of varied age is used to derive a transfer function for the reconstruction of chemical trends from fossil assemblages in sediment cores. The modem data suggest that pH and TN (total nitrogen) exert significant and independent controls on diatom distributions, and thus trends in these variables are reconstructed for Bartlett Lake, as an example of our approach. Core reconstruction corroborates patterns in pH suggested by the modem chronosequence and shows a gradual decline in lake water pH after about 100 years. The Bartlett Lake core also follows the chronosequence pattern in TN concentration, with an initial increase followed by a decline after ca. 100 years. Reconstructions from other sites, however, suggest that trends in total nitrogen concentration are variable, and thus that localized patterns of plant colonization and soil development may result in regional variability in lake water nitrogen concentration over time

Noise-free high-efficiency photon-number-resolving detectors

High-efficiency optical detectors that can determine the number of photons in a pulse of monochromatic light have applications in a variety of physics studies, including post-selection-based entanglement protocols for linear optics quantum computing and experiments that simultaneously close the detection and communication loopholes of Bell's inequalities. Here we report on our demonstration of fiber-coupled, noise-free, photon-number-resolving transition-edge sensors with 88% efficiency at 1550 nm. The efficiency of these sensors could be made even higher at any wavelength in the visible and near-infrared spectrum without resulting in a higher dark-count rate or degraded photon-number resolution.Comment: 4 pages, 4 figures Published in Physical Review A, Rapid Communications, 17 June 200

R ates and factors associated with falls in older European Americans, Afro-Caribbeans, African-Americans, and Hispanics

Purpose: To evaluate rates and factors associated with older adult falls in different ethnic groups. Participants and methods: Information on demographics, medical and falls history, and pain and physical activity levels was collected from 550 community-dwelling older adults (75±9 years old, 222 European Americans, 109 Afro-Caribbeans, 106 African-Americans, and 113 Hispanics). Results: Taking medications for anxiety (risk ratio [RR] =1.4, 95% confidence interval [CI] =1.1–2.0), having incontinence (RR =1.4, 95% CI =1.1–1.8, P=0.013), back pain (RR =1.4, 95% CI =1.0–1.8), feet swelling (RR =1.3, 95% CI =1.1–1.7), and age $75 years (RR =1.3, 95$75 years were associated with falls, and Afro-Caribbeans presented lower prevalence of falls. These findings need to be taken into consideration in clinical interventions in aging. Keywords: ethnicity, falls, risks, community dwelling, older adult

The role of earth observation in an integrated deprived area mapping “system” for low-to-middle income countries

Urbanization in the global South has been accompanied by the proliferation of vast informal and marginalized urban areas that lack access to essential services and infrastructure. UN-Habitat estimates that close to a billion people currently live in these deprived and informal urban settlements, generally grouped under the term of urban slums. Two major knowledge gaps undermine the efforts to monitor progress towards the corresponding sustainable development goal (i.e., SDG 11—Sustainable Cities and Communities). First, the data available for cities worldwide is patchy and insufficient to differentiate between the diversity of urban areas with respect to their access to essential services and their specific infrastructure needs. Second, existing approaches used to map deprived areas (i.e., aggregated household data, Earth observation (EO), and community-driven data collection) are mostly siloed, and, individually, they often lack transferability and scalability and fail to include the opinions of different interest groups. In particular, EO-based-deprived area mapping approaches are mostly top-down, with very little attention given to ground information and interaction with urban communities and stakeholders. Existing top-down methods should be complemented with bottom-up approaches to produce routinely updated, accurate, and timely deprived area maps. In this review, we first assess the strengths and limitations of existing deprived area mapping methods. We then propose an Integrated Deprived Area Mapping System (IDeAMapS) framework that leverages the strengths of EO- and community-based approaches. The proposed framework offers a way forward to map deprived areas globally, routinely, and with maximum accuracy to support SDG 11 monitoring and the needs of different interest groups

Development of high-gain gaseous photomultipliers for the visible spectral range

We summarize the development of visible-sensitive gaseous photomultipliers, combining a semitransparent bi-alkali photocathode with a state-of-the-art cascaded electron multiplier. The latter has high photoelectron collection efficiency and a record ion blocking capability. We describe in details the system and methods of photocathode production and characterization, their coupling with the electron multiplier and the gaseous-photomultiplier operation and characterization in a continuous mode. We present results on the properties of laboratory-produced K$_2$CsSb, Cs$_3$Sb and Na$_2$KSb photocathodes and report on their stability and QE in gas; K$_2$CsSb photocathodes yielded QE values in Ar/CH$_4$(95/5) above 30% at wavelengths of 360-400 nm. The novel gaseous photomultiplier yielded stable operation at gains of 10$^5$, in continuous operation mode, in 700 Torr of this gas; its sensitivity to single photons was demonstrated. Other properties are described. The successful detection of visible light with this gas-photomultiplier pave ways towards further development of large-area sealed imaging detectors, of flat geometry, insensitive to magnetic fields, which might have significant impact on light detection in numerous fields.Comment: 22 pages, 12 figures, for submission to JINS

Health Coaching in Primary Care: A Pilot Study

Undergraduate Research Opportunity Program (UROP)http://deepblue.lib.umich.edu/bitstream/2027.42/116124/1/Health_Coaching_In_Primary_Care.pd