Do Start-Ups Pay Less?

The authors analyze Danish registry data from 1991 to 2006 to determine how firm age and firm size influence wages. Unadjusted statistics suggest that smaller firms paid less than larger firms paid, and that firm age had little or no bearing on wages. After adjusting for differences in the characteristics of employees hired by these firms, however, they observe both firm age and firm size effects. Larger firms paid more than did smaller firms for observationally equivalent individuals but, contrary to conventional wisdom, younger firms paid more than older firms. The size effect, however, dominates the age effect. Thus, although the typical start-up — being both young and small — paid less than a more established employer, the largest start-ups paid a wage premium

Education in Pediatrics in US Colleges and Schools of Pharmacy

Objective. To determine the extent to which pediatrics is taught at US doctor of pharmacy (PharmD) programs and to characterize what is being taught and how. Methods. A 40-question online survey instrument was sent to accredited and candidate-status US PharmD programs. Results. Of 86 participating programs (67.2% response rate), 81 (94.2%) indicated that pediatric topics were included in their required classroom curricula (mean, 21.9 contact hours). A pediatric elective course was offered by 61.0% of programs (mean, 25.9 contact hours). Advanced pharmacy practice experiences (APPEs) in pediatrics were offered by 97.4% of programs, with an average of 27 students per program completing this practice experience annually. Conclusions. Almost all responding programs incorporated pediatrics in their required curricula. Pediatric elective courses provided an adequate mean number of contact hours, but 39.0% of programs did not offer an elective course. One-fifth of students completed a pediatric APPE prior to graduation. Continued expansion of pediatric-focused classroom and experiential curricula across US PharmD programs is recommended

Measured acoustic properties of variable and low density bulk absorbers

Experimental data were taken to determine the acoustic absorbing properties of uniform low density and layered variable density samples using a bulk absober with a perforated plate facing to hold the material in place. In the layered variable density case, the bulk absorber was packed such that the lowest density layer began at the surface of the sample and progressed to higher density layers deeper inside. The samples were placed in a rectangular duct and measurements were taken using the two microphone method. The data were used to calculate specific acoustic impedances and normal incidence absorption coefficients. Results showed that for uniform density samples the absorption coefficient at low frequencies decreased with increasing density and resonances occurred in the absorption coefficient curve at lower densities. These results were confirmed by a model for uniform density bulk absorbers. Results from layered variable density samples showed that low frequency absorption was the highest when the lowest density possible was packed in the first layer near the exposed surface. The layers of increasing density within the sample had the effect of damping the resonances

Some Observations on Transitory Stall in Conical Diffusers

Results from an experimental investigation on the flow through conical diffusers are presented. The mean and fluctuating velocity fields are compared for three diffusers with total diffusion angles of 16, 20 and 24 degrees, in the throat Mach number (M sub t) range of 0.05 to 0.95. Each of the diffusers were 14 cm long and had a 5.08 cm inlet diameter, and the flow exited into the ambient. The boundary layer at the throat was thin with the throat diameter (D sub t) to momentum thickness (O) ratio being as high as 800 at M(sub t) = 0.4. While the 16 deg diffuser flow exited with a top-hat mean velocity profile, increasing losses due to increasing separation resulted in fuller profiles for the 20 and 24 degree cases. A detailed flow field study was conducted for the 16 deg. diffuser. The u'-spectrum, measured at the exit plane, exhibited a peak apparently due to the ensuing jet column instability throughout the M(sub t) range covered. In addition, a much lower frequency spectral peak also occurred in the M(sub t) range of 0.3 to 0.7. Both of the spectral peaks were due to axisymmetric flow fluctuations. A self-sustaining flow oscillation occurred in the M(sub t) range of 0.6 to 0.85, emitting a loud tone, when the jet column instability frequency matched the resonance frequency of the diffuser. Limited data showed that artificial acoustic excitation was effective in reducing the flow fluctuations, with a resultant increase in the pressure recovery, at low M(sub t)

Priorities for sustainable turfgrass management: a research and industry perspective

This paper provides a brief review and assessment of the key environmental, regulatory and technical issues facing the turfgrass sector with specific reference to the European context. It considers the range of externalities or ‘drivers for change' facing the industry, and the challenges and opportunities available for promoting and achieving more sustainable turfgrass management within the sports, landscape and amenity sectors. The analysis confirms that there are a number of key areas where a concerted research and industrial effort is required. These include responding to the pressures from government demands for greater environmental regulation, the increasing pressure on natural resources (notably water, energy and land), the emerging role of turf management in supporting ecosystem services and enhancing biodiversity, the continued need to promote integrated pest management, and the looming challenges posed by a changing climate, and urgent need to adapt. Whilst many of these externalities appear to be risks to the sports turf industry, there will also be significant opportunities, for those where the labour, energy and agronomic costs are minimized and where the drive to adopt a multifunctional approach to sportsturf management is embraced

The Really, Really Empty Nest: Single Parents Launching Only Children

When only children of single parents leave home, the nest is really, really empty. This situation requires particular understanding and certainly is an area for fruitful ministry

Characterisation and representation of non-dissipative electromagnetic medium with a double light cone

We study Maxwell's equations on a 4-manifold N with a medium that is non-dissipative and has a linear and pointwise response. In this setting, the medium can be represented by a suitable (2,2)-tensor on the 4-manifold N. Moreover, in each cotangent space on N, the medium defines a Fresnel surface. Essentially, the Fresnel surface is a tensorial analogue of the dispersion equation that describes the response of the medium for signals in the geometric optics limit. For example, in isotropic medium the Fresnel surface is at each point a Lorentz light cone. In a recent paper, I. Lindell, A. Favaro and L. Bergamin introduced a condition that constrains the polarisation for plane waves. In this paper we show (under suitable assumptions) that a slight strengthening of this condition gives a pointwise characterisation of all medium tensors for which the Fresnel surface is the union of two distinct Lorentz null cones. This is for example the behaviour of uniaxial medium like calcite. Moreover, using the representation formulas from Lindell et al. we obtain a closed form representation formula that pointwise parameterises all medium tensors for which the Fresnel surface is the union of two distinct Lorentz null cones. Both the characterisation and the representation formula are tensorial and do not depend on local coordinates