Macroeconomic implications of changes in micro volatility

We review evidence on the Great Moderation in conjunction with evidence about volatility trends at the micro level. We combine the two types of evidence to develop a tentative story for important components of the aggregate volatility decline and its consequences. The key ingredients of the story are declines in firm-level volatility and aggregate volatility – most dramatically in the durable goods sector – but the absence of a decline in the volatility of household consumption and individual earnings. Our explanation for volatility reduction stresses improved supply chain management, particularly in the durable goods sector, and a shift in production and employment from goods to services. We also provide some evidence for a specific mechanism, namely shorter lead times for materials orders. The tentative conclusion we draw is that, although better supply chain management involves potentially large efficiency gains with first-order effects on welfare, it does not imply (nor is there much evidence for) a reduction in uncertainty faced by individuals.

Effect of Socio-Demographics, Health-Related Problems, and Family Structure on Chronic Absenteeism Among Children

Purpose/Background: From 5 to 7.5 million school children are chronically absent, defined as missing ≥15 days of school within a year. Students miss schools due to various reasons such as health, socioeconomic status, and environmental factors. We examined child’s health and behavior, family structure, and socio-demographics to understand chronic absenteeism. Materials & Methods: The population included children ages 6 to 17 years from the Medical Expenditure Panel Survey (MEPS) years 2008-2013. Multivariable logistic regressions were used to identify the risk factors of chronic absenteeism, adjusting for the complex sampling design. Results: Among socio-demographic variables, age ≥14 years, race/ethnicity, lower-income family, public health insurance, US-born, and speaking English at home were associated with chronic absenteeism. Asians, Mexican Hispanics, and blacks have lower chronic absenteeism than whites. Among health-related variables, children using an inhaler for asthma, having behavioral problems, and less healthy than other children were more likely to be chronically absent. Among family variables, a smaller family size was a risk factor for chronic absenteeism. Discussion/Conclusion: Asthma and behavioral problems were highly associated with chronic absenteeism. The identification of children at risk for chronic absenteeism will help the educational professionals identify the barriers to academic achievements and develop integrated educational interventions and policies to support disadvantaged children

Type Ia supernova diversity: Standardizing the candles

Future use of type Ia supernovae for cosmology aims not only to determine the equation of state of dark energy, but also to constrain possible variations in its value. To achieve this goal, supernovae need to become better calibrated standard candles - not only to improve the precision of the measurement, but more importantly to gain better control over systematic uncertainties in order to ensure the accuracy of the result. Here we report on a project to quantify the diversity in type Ia supernovae, and to look for trends and/or sub-types that can be used to improve their calibration as standard candles. We implement a version of principal component analysis on type Ia supernova spectra. Although the quantity of data is not sufficient to draw any firm conclusions we show that this method holds promise for, at the very least, effectively separating peculiar supernovae. Whether it can be further used to improve the calibration of normal type Ia's remains a project for future study.Comment: Conference Proceedings. Cefalu 2006, The multicoloured landscape of compact objects and their explosive origins. Six pages, three figure

Peak-to-mean power control and error correction for OFDM transmission using Golay sequences and Reed-Muller codes

A coding scheme for OFDM transmission is proposed, exploiting a previously unrecognised connection between pairs of Golay complementary sequences and second-order Reed-Muller codes. The scheme solves the notorious problem of power control in OFDM systems by maintaining a peak-to-mean envelope power ratio of at most 3dB while allowing simple encoding and decoding at high code rates for binary, quaternary or higher-phase signalling together with good error correction

FLOWERING LOCUS C -dependent and -independent regulation of the circadian clock by the autonomous and vernalization pathways

Background The circadian system drives pervasive biological rhythms in plants. Circadian clocks integrate endogenous timing information with environmental signals, in order to match rhythmic outputs to the local day/night cycle. Multiple signaling pathways affect the circadian system, in ways that are likely to be adaptively significant. Our previous studies of natural genetic variation in Arabidopsis thaliana accessions implicated FLOWERING LOCUS C (FLC) as a circadian-clock regulator. The MADS-box transcription factor FLC is best known as a regulator of flowering time. Its activity is regulated by many regulatory genes in the "autonomous" and vernalization-dependent flowering pathways. We tested whether these same pathways affect the circadian system. Results Genes in the autonomous flowering pathway, including FLC, were found to regulate circadian period in Arabidopsis. The mechanisms involved are similar, but not identical, to the control of flowering time. By mutant analyses, we demonstrate a graded effect of FLC expression upon circadian period. Related MADS-box genes had less effect on clock function. We also reveal an unexpected vernalization-dependent alteration of periodicity. Conclusion This study has aided in the understanding of FLC's role in the clock, as it reveals that the network affecting circadian timing is partially overlapping with the floral-regulatory network. We also show a link between vernalization and circadian period. This finding may be of ecological relevance for developmental programing in other plant species