151,042 research outputs found
Systematic Behavior in Real Estate Investment Risk: Performance Persistence in NCREIF Returns
Serial dependence of total annual returns in the NCREIF database is shown to be statistically significant in the first and fourth quartiles of disaggregated data between 1978 and 1994. More precisely, superior performance is generally followed by continued superior performance, and inferior performance is generally followed by continued inferior performance. In contrast, there is virtually no evidence to support serial dependence in the second or third quartiles, whether combined or taken separately. The empirical rejection of serial independence among real estate returns calls into question the conclusions of research based upon models that incorporate the assumption of serial independence.
University Endowment Growth: Assessing Policy Proposals
The growth of college and university endowments, particularly those of elite schools, have drawn the attention of policymakers and pundits. Using a decomposition of the growth of endowments between 1991 and 2010 we simulate the effects of three prominent proposed policies had they been implemented in 1991 on endowment payouts through 2010: (1) a minimum spending rule, (2) removing full income tax deductibility of donations, and (3) taxing total endowment sizes beyond a given size. We find that a minimum spending rule increases the average size of endowment payouts for all quartiles of the endowment distribution in nearly all years of the sample period and has a modestly larger relative impact on richer schools. Removing tax deductibility decreases endowment payouts with its effect increasing over time. It has a larger relative impact on schools with smaller endowments than on richer schools
Ambient Air Toxic Releases and Adverse Pregnancy Outcomes in Allegheny County, Pennsylvania
Previous studies have shown that women exposed to certain air pollutants are at an increased risk for preterm delivery and/or delivering a low birth weight newborn. Preterm delivery and low birth weight are associated with an increased risk for morbidity and mortality. In an effort to better understand the impact of local environmental factors on pregnancy health, duration and outcomes, this study investigated the relationship of hazardous air pollutant chemicals released by local industries and the adverse pregnancy outcomes of preterm delivery and term low birth weight in Allegheny County, PA.This study included 2,798 singleton birth records for deliveries that occurred in Allegheny County in January through March of 2004. The Toxic Release Inventory provided data for 2003 fugitive and stack air releases of all facilities in Allegheny County reporting air releases of lead and toluene. This data was used for determining proxy maternal exposure measurements. ArcGIS software was used to calculate the distance from each maternal residence to each TRI facility. The distances and reported total pounds of release from each facility were then used to calculate a total lead and toluene exposure value for every birth record. Binary logistic regression was used to assess maternal characteristics' effects on birth outcomes. Chi square tests were used to assess maternal characteristics and levels of exposure to lead and toluene. Chi square tests and binary logistic regression were then used to assess pregnancy outcomes in relation to quartiles of exposure.This study found that mothers with certain age, race, education, and marital characteristics were significantly associated with lower exposure levels of lead and toluene. However, exposure to higher levels of lead or toluene, as measured in this study, was not significantly associated with an increased risk for preterm delivery or term low birth weight.Adverse pregnancy outcomes negatively impact an individual's immediate and lifelong health. Decreasing the incidence of preterm delivery and low birth weight are of great importance to public health. Research that helps to identify environmental determinants of adverse pregnancy outcomes is of vital public health significance
Maximum Entropy Production Principle for Stock Returns
In our previous studies we have investigated the structural complexity of
time series describing stock returns on New York's and Warsaw's stock
exchanges, by employing two estimators of Shannon's entropy rate based on
Lempel-Ziv and Context Tree Weighting algorithms, which were originally used
for data compression. Such structural complexity of the time series describing
logarithmic stock returns can be used as a measure of the inherent (model-free)
predictability of the underlying price formation processes, testing the
Efficient-Market Hypothesis in practice. We have also correlated the estimated
predictability with the profitability of standard trading algorithms, and found
that these do not use the structure inherent in the stock returns to any
significant degree. To find a way to use the structural complexity of the stock
returns for the purpose of predictions we propose the Maximum Entropy
Production Principle as applied to stock returns, and test it on the two
mentioned markets, inquiring into whether it is possible to enhance prediction
of stock returns based on the structural complexity of these and the mentioned
principle.Comment: 14 pages, 5 figure
Submillimeter Atmospheric Transparency at Maunakea, at the South Pole, and at Chajnantor
For a systematic assessment of submillimeter observing conditions at
different sites, we constructed tipping radiometers to measure the broad band
atmospheric transparency in the window around 350 m wavelength. The
tippers were deployed on Maunakea, Hawaii, at the South Pole, and in the
vicinity of Cerro Chajnantor in northern Chile. Identical instruments permit
direct comparison of these sites. Observing conditions at the South Pole and in
the Chajnantor area are better than on Maunakea. Simultaneous measurements with
two tippers demonstrate conditions at the summit of Cerro Chajnantor are
significantly better than on the Chajnantor plateau.Comment: Accepted by PAS
Vitamin D and Disease Severity in Multiple Sclerosis-Baseline Data From the Randomized Controlled Trial (EVIDIMS)
Objective: To investigate the associations between hypovitaminosis D and disease activity in a cohort of relapsing remitting multiple sclerosis (RRMS) and clinically isolated syndrome (CIS) patients.
Methods: In 51 RRMS and 2 CIS patients on stable interferon-β-1b (IFN-β-1b) treatment recruited to the EVIDIMS study (Efficacy of Vitamin D Supplementation in Multiple Sclerosis (NCT01440062) baseline serum vitamin D levels were evaluated. Patients were dichotomized based on the definition of vitamin D deficiency which is reflected by a < 30 vs. ≥ 30 ng/ml level of 25-hydroxyvitamin D (25(OH)D). Possible associations between vitamin D deficiency and both clinical and MRI features of the disease were analyzed.
Results: Median (25, 75% quartiles, Q) 25(OH)D level was 18 ng/ml (12, 24). Forty eight out of 53 (91%) patients had 25(OH)D levels < 30 ng/ml (p < 0.001). Patients with 25(OH)D ≥ 30 ng/ml had lower median (25, 75% Q) T2-weighted lesion counts [25 (24, 33)] compared to patients with 25(OH)D < 30 ng/ml [60 (36, 84), p = 0.03; adjusted for age, gender and disease duration: p < 0.001]. Expanded disability status scale (EDSS) score was negatively associated with serum 25(OH)D levels in a multiple linear regression, including age, sex, and disease duration (adjusted: p < 0.001).
Interpretation: Most patients recruited in the EVIDIMS study were vitamin D deficient. Higher 25(OH)D levels were associated with reduced T2 weighted lesion count and lower EDSS scores
Differing instructional needs for children of similar reading achievement grades two, four, and six
Thesis (Ed.M.)--Boston Universit
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