Volatility and Dispersion in Business Growth Rates: Publicly Traded versus Privately Held Firms

We study the variability of business growth rates in the U.S. private sector from 1976 onwards. To carry out our study, we exploit the recently developed Longitudinal Business Database (LBD), which contains annual observations on employment and payroll for all U.S. businesses. Our central finding is a large secular decline in the cross sectional dispersion of firm growth rates and in the average magnitude of firm level volatility. Measured the same way as in other recent research, the employment-weighted mean volatility of firm growth rates has declined by more than 40% since 1982. This result stands in sharp contrast to previous findings of rising volatility for publicly traded firms in COMPUSTAT data. We confirm the rise in volatility among publicly traded firms using the LBD, but we show that its impact is overwhelmed by declining volatility among privately held firms. This pattern holds in every major industry group. Employment shifts toward older businesses account for 27 percent or more of the volatility decline among privately held firms. Simple cohort effects that capture higher volatility among more recently listed firms account for most of the volatility rise among publicly traded firms.

Turmoil and Growth: Young Businesses, Economic Churning, and Productivity Gains

Summarizes research on how the establishment or failure of businesses contribute to job creation or destruction, how a young firm's contribution evolves as it matures, and how this process of new firms displacing old ones enhances productivity growth

Infrared Thermographic Evaluation of Commercially Available Incandescent Heat Lamps

Infrared thermography is a useful tool in visualizing and quantifying spatial distribution in radiant heat of incandescent heat lamps. Radial temperature profiles of six commercially available heat lamps (100W to 250W) were comparatively characterized. Heat lamps with the same power output do not necessarily produce the same temperature profiles on the heated surface because the shape of the temperature profiles was shown to be greatly affected by the lamp lens prescription. At a lamp height of 45.7 cm (18 in.), the net usable area (NUA) for the piglets was 0.102, 0.155, 0.146, 0.275, 0.139 and 0.113 m2 (1.10, 1.67, 1.57, 2.96, 1.50, and 1.22 ft2), respectively, for 100W Retrolite (100CZ20), 125W Hogslat (125HOG), 125W SLI Lighting (125SLI), 175W Retrolite (175CZ20), 175W Phillips (175PLP), and 250W SLI Lighting (250SLI). The 175CZ20 had the largest NUA and was the most efficient lamp on the basis of NUA per rated Watt. Although the 250SLI had the largest lamp heated area, it and the 175PLP were the least efficient lamps due to the large hotspots they produced. Lamp height affects the size of heated area, hotspot area and NUA for most of the lamps tested. These results suggest that in a commercial swine farrowing system, the 175CZ20 has the most potential among the incandescent heat lamps tested for meeting the thermal needs of the piglets and improving energy efficiency of the localized supplemental heating

Measuring the Dynamics of Young and Small Businesses: Integrating the Employer and Nonemployer Universes

We develop a preliminary version of an Integrated Longitudinal Business Database (ILBD) that combines administrative records and survey data for all employer and nonemployer business units in the United States. Unlike other large-scale business databases, the ILBD tracks business transitions from nonemployer to employer status. This feature of the ILBD opens a new frontier for the study of business formation, early lifecycle dynamics and the precursors to job creation in the U.S. economy. There are 5.4 million nonfarm business firms with employees as of 2000 and another 15.5 million with no employees. Our analysis focuses on 40 industries that account for nearly half of nonemployers and 36 percent of nonemployer revenues. Within these industries, nonemployers account for 14 percent of business revenues. About 220,000 of the seven million nonemployers in our selected industries hire workers and migrate to the employer universe over a three-year horizon. These Migrants account for 20 percent of revenue among young employers (three years or less since first hire). Compared to other nonemployers, the revenue of Migrants grows very rapidly in the year prior to and the year of transition to employer status.

Infrared Thermography Evaluation of Commercially Available Infrared Heat Lamps

The objectives of this study were i) to comparatively characterize the radial temperature distribution of six commercially available heat lamps (100W to 250W) at different heights (45-66 cm or 18-26 in) when used with a commercially available plastic lamp fixture and ii) to evaluate the operation of a commercially available power controller used with the 175SYL heat lamp at a 51-cm (20-in) height for three power settings of 100, 125 and 175W.Heat lamps with the same power output do not necessarily produce the same temperature profiles along the heated surface. Lamp lens prescriptions greatly affect the shape of the profile. By using a power controller with a given bulb, varying temperature ranges can be achieved while reducing overall energy as compared to varying height with same bulb

Fish recolonization in temperate Australian rockpools: a quantitative experimental approach

Understanding recolonization processes of intertidal fish assemblages is integral for predicting the consequences of significant natural or anthropogenic impacts on the intertidal zone. Recolonization of experimentally defaunated intertidal rockpools by fishes at Bass Point, New South Wales (NSW), Australia, was assessed quantitatively by using one long-term and two short-term studies. Rockpools of similar size and position at four sites within the intertidal zone were repeatedly defaunated of their fish fauna after one week, one month, and three months during two shortterm studies in spring and autumn (5 months each), and every six months for the long-term study (12 months). Fish assemblages were highly resilient to experimental perturbations—recolonizing to initial fish assemblage structure within 1−3 months. This recolonization was primarily due to subadults (30−40 mm TL) and adults (>40 mm TL) moving in from adjacent rockpools and presumably to abundant species competing for access to vacant habitat. The main recolonizers were those species found in highest numbers in initial samples, such as Bathygobius cocosensis, Enneapterygius rufopileus, and Girella elevata. Defaunation did not affect the size composition of fishes, except during autumn and winter when juveniles (<30 mm TL) recruited to rockpools. It appears that Bass Point rockpool fish assemblages are largely controlled by postrecruitment density-dependent mechanisms that indicate that recolonization may be driven by deterministic mechanisms

Significance Analysis of Time Course Microarray Experiments

Characterizing the genome-wide dynamic regulation of gene expression is important and will be of much interest in the future. However, there is currently no established method for identifying differentially expressed genes in a time course study. Here we propose a significance method for analyzing time course microarray studies that can be applied to the typical types of comparisons and sampling schemes. This method is applied to two studies on humans. In one study, genes are identified that show differential expression over time in response to in vivo endotoxin administration. Using our method 7409 genes are called significant at a 1% FDR level, whereas several existing approaches fail to identify any genes. In another study, 417 genes are identified at a 10% FDR level that show expression changing with age in the kidney cortex. Here it is also shown that as many as 47% of the genes change with age in a manner more complex than simple exponential growth or decay. The methodology proposed here has been implemented in the freely distributed and open-source EDGE software package

Definition of the mole (IUPAC Recommendation 2017)

In 2011 the General Conference on Weights and Measures (CGPM) noted the intention of the International Committee for Weights and Measures (CIPM) to revise the entire International System of Units (SI) by linking all seven base units to seven fundamental physical constants. Of particular interest to chemists, new definitions for the kilogram and the mole have been proposed. A recent IUPAC Technical Report discussed these new definitions in relation to immediate consequences for the chemical community. This IUPAC Recommendation on the preferred definition of the mole follows from this Technical Report. It supports a definition of the mole based on a specified number of elementary entities, in contrast to the present 1971 definition.Peer reviewed: YesNRC publication: Ye