Stock return autocorrelations revisited: A quantile regression approach

The aim of this study is to provide a comprehensive description of the dependence pattern of stock returns by studying a range of quantiles of the conditional return distribution using quantile autoregression. This enables us in particular to study the behavior of extreme quantiles associated with large positive and negative returns in contrast to the central quantile which is closely related to the conditional mean in the least-squares regression framework. Our empirical results are based on 30 years of daily, weekly and monthly returns of the stocks comprised in the Dow Jones Stoxx 600 index. We find that lower quantiles exhibit positive dependence on past returns while upper quantiles are marked by negative dependence. This pattern holds when accounting for stock specific characteristics such as market capitalization, industry, or exposure to market risk. --stock return distribution,quantile autoregression,overreaction and underreaction

Evaluating Educational Inputs in Undergraduate Education

This paper examines the input-output relationship for private undergraduate education. The motivation for such a study stems from a long-standing concern within academe for a better understanding of the relationships between student quality, faculty effort, campus environment, and the end result of an “educated” person. Though precise and objective measures of education output are difficult to formulate, we would argue that alumni achievement is an important and measurable output. Specifically we focus on the number of baccalaureate alumni who went on to earn a Ph.D. But even with an acceptable output measure, research assessments of the educational process are not dealing with a production function in the classical supply-and-demand sense. For example, the purchaser of the product-the student-is also among the more important factor inputs. The implication is that the educational process is far more complicated than a simple, production-function rendering indicates. Consequently, this study formulates a three-equation simultaneous model of student quality, faculty quality, and output. The study’s objective is to identify the relative contribution of the many human and nonhuman resources commonly regarded as producing quality undergraduate education

Research Issues in the Economics of Education and Growth

Economic growth and public education are two areas which in recent years have been the objects of increasing interest and concern. From the standpoint of economic growth, the decade of the 70s brought some alarming developments. Adverse supply shocks, declining productivity, and intense international competition combined to foster a new awareness and advocacy with respect to strategies for economic growth. Over roughly the same period, observers of our educational process cited mounting evidence of the gradual deterioration in the quality of public schools. In 1983 the President\u27s own blue-ribbon committee lent its official determination that, from an educational standpoint, we are indeed a nation at risk. The national reaction tot his report has been dramatic, swift, and still growing. In short, it seems clear that in the decade of the 80s the issues of economic growth and public education will remain at the top of the political agendas on the national, state, and local levels

Evaluating Educational Inputs in Undergraduate Education

This paper examines the input-output relationship for private undergraduate education. The motivation for such a study stems from a long-standing concern within academe for a better understanding of the relationships between student quality, faculty effort, campus environment, and the end result of an educated person. Though precise and objective measures of educational output are difficult to formulate, we would argue that alumni achievement is an important and measurable output. Specifically, we focus on the number of baccalaureate alumni who went on to earn a Ph.D. But even with an acceptable output measure, research assessments of the educational process are not dealing with a production function in the classical supply-and-demand sense. For example, the purchaser of the product—the student—is also among the more important factor inputs. The implication is that the educational process is far more complicated than a simple, production-function rendering indicates. Consequently, this study formulates a three-equation simultaneous model of student quality, faculty quality and output. The study\u27s objective is to identify the relative contribution of the many human and nonhuman resources commonly regarded as producing quality undergraduate education

T lymphocytes from patients with primary biliary cirrhosis produce reduced amounts of lymphotoxin, tumor necrosis factor and interferon-gamma upon mitogen stimulation

Primary biliary cirrhosis (PBC) is considered an autoimmune disease characterized by destruction of small intrahepatic bile ducts by lymphocytes. Altered functions of these lymphocytes might reflect an abnormal immune response leading to tissue damage. We investigated lymphokine secretion by mitogen-stimulated T lymphocytes from the liver biopsies of patients with PBC and for comparison also peripheral blood. In PBC, diminished synthesis of lymphotoxin (TNFP), tumor necrosis factor (TNFa) and interferon-y (IFIVy) was found both in T-cell lines from liver tissue and in peripheral blood. The reduction was most prominent for TNFP in early histological stages of PBC, and appeared to be a stable phenomenon when T cells were tested after long-term tissue culture. Analysis of mRNA levels indicates a possible link between reduced TNFP production and a defect in interleukin-2 transcription. The data suggest that diminished lymphokine production in patients with PBC may play ;In important role in the immanopathogenesis of this disease

Pubertal timing and breast density in young women: a prospective cohort study.

BACKGROUND:Earlier age at onset of pubertal events and longer intervals between them (tempo) have been associated with increased breast cancer risk. It is unknown whether the timing and tempo of puberty are associated with adult breast density, which could mediate the increased risk. METHODS:From 1988 to 1997, girls participating in the Dietary Intervention Study in Children (DISC) were clinically assessed annually between ages 8 and 17 years for Tanner stages of breast development (thelarche) and pubic hair (pubarche), and onset of menses (menarche) was self-reported. In 2006-2008, 182 participants then aged 25-29 years had their percent dense breast volume (%DBV) measured by magnetic resonance imaging. Multivariable, linear mixed-effects regression models adjusted for reproductive factors, demographics, and body size were used to evaluate associations of age and tempo of puberty events with %DBV. RESULTS:The mean (standard deviation) and range of %DBV were 27.6 (20.5) and 0.2-86.1. Age at thelarche was negatively associated with %DBV (p trend = 0.04), while pubertal tempo between thelarche and menarche was positively associated with %DBV (p trend = 0.007). %DBV was 40% higher in women whose thelarche-to-menarche tempo was 2.9 years or longer (geometric mean (95%CI) = 21.8% (18.2-26.2%)) compared to women whose thelarche-to-menarche tempo was less than 1.6 years (geometric mean (95%CI) = 15.6% (13.9-17.5%)). CONCLUSIONS:Our results suggest that a slower pubertal tempo, i.e., greater number of months between thelarche and menarche, is associated with higher percent breast density in young women. Future research should examine whether breast density mediates the association between slower tempo and increased breast cancer risk

Analysis of At-Altitude LTE Power Spectra for C2 Communications for UAS Traffic Management

The National Aeronautics and Space Administrations (NASA) Unmanned Aircraft Systems Traffic Management (UTM) project works to develop tools and technologies essential for safely enabling civilian low-altitude small Unmanned Aerial Systems (sUAS, also known as drones) operations. This paper presents results of work completed in the paper [1] presented at the 2018 ICNS conference where proposed approaches were explored for evaluating and analyzing sUAS Command and Control (C2) links based on commercial cellular networks. This paper focuses on the UTM Projects Technology Capability Level 3 (TCL-3) test results which address the communications portion identified within the same paper. A software defined radio (SDR) was flown as a sUAS payload to capture received signal spectrum in Long Term Evolution (LTE) frequency bands of interest. The purpose was to measure the RF environment at UTM altitudes to characterize the interference potential. The SDR payload was flown at various stationary altitudes where the LTE over-the-air complex (I/Q) samples were captured by the SDR and later post-processed. The SDR received inputs through an omnidirectional antenna. The complex samples captured were an aggregate of transmissions received from all line-of-sight (LOS) towers within the geographic area for the specific radio frequency bandwidth the SDR is programmed to capture. Using this approach, the complex samples captured do not distinguish between the various eNodeB's (Long Term Evolution (LTE) transmitting towers). The complex samples were post processed via a Discrete Fourier Transform (DFT) algorithm to view the captured spectrum along with the power levels across the captured LTE bandwidth. This SDR payload process of capturing complex samples was done at two different regions within the US: 1) NASA's Ames Research Center (ARC) in Moffett Field, CA, and 2) Griffiss Airfield in Rome, NY. The data capture at the ARC site was done at two physical locations within the Ames campus where many stationary altitude captures where done as high as 800 ft. above ground level (AGL). The data captured at the Griffiss Airport (also known as the NY Corridor Site) were acquired at one location with three specific stationary altitude levels {Ground Level (GL), 300 ft., and 400 ft.}. The LTE spectrum power levels were captured for two LTE carriers, AT&T and Verizon, at both sites where their respective spectra and power levels were measured and compared at various altitudes. The overall results show that there is an increase in LTE spectrum power levels at higher altitudes for drones. A detailed analysis of this data and conclusions drawn from the results are presented in this paper