The Ghost of Extinction: Preservation Values and Minimum Viable Population in Wildlife Models

The inclusion of a minimum viable population in bioeconomic modeling creates at least two complications that are not resolved by using a modified logistic growth function. The first complication can be dealt with by choosing a different depensational growth function. The second complication relates to the inclusion of the in situ benefits of wildlife into the analysis. Knowledge about the magnitude of the in situ benefits provides no guide for policy about conservation management. Simply knowing that people are willing to pay a large amount each year to protect a species says nothing about whether one should manage habitat to protect or enhance the species numbers, unless the species is in imminent danger of extinction. If willingness to pay is to be a guide, it needs to be better tied to population numbers, especially the minimum viable population.marginal willingness to pay, endangered species and extinction, minimum viable population, Resource /Energy Economics and Policy, Q20, Q24, C61,

Persistence-driven durotaxis: Generic, directed motility in rigidity gradients

Cells move differently on substrates with different elasticities. In particular, the persistence time of their motion is higher on stiffer substrates. We show that this behavior will result in a net transport of cells directed up a soft-to-stiff gradient. Using simple random walk models with controlled persistence and stochastic simulations, we characterize this propensity to move in terms of the durotactic index measured in experiments. A one-dimensional model captures the essential features of this motion and highlights the competition between diffusive spreading and linear, wavelike propagation. Since the directed motion is rooted in a non-directional change in the behavior of individual cells, the motility is a kinesis rather than a taxis. Persistence-driven durokinesis is generic and may be of use in the design of instructive environments for cells and other motile, mechanosensitive objects.Comment: 5 pages, 4 figure

Modeling and Compensation of Nonlinear Distortion in Horn Loudspeakers

Horn loaded compression drivers are widely used in the area where high sound pressure levels together with good directivity characteristics are needed. Major disadvantage of this kind of drivers is the considerable amount of nonlinear distortion. Due to the quite high air pressures in the driver the air is driven into its nonlinear range. This paper describes a technique to reduce the distortion caused by this phenomenon. Using a Digital Signal Processor (DSP), a feedforward compensation technique, based on an equivalent lumped parameter circuit, is implemented and tested in real–time in series with the loudspeaker. Measurement and simulation results are given. The overall conclusion is that a distortion reduction is obtained in the frequency span from 600 to 1050 Hz

Ovarian reserve and anti-Mullerian hormone (AMH) in mothers of dizygotic twins

This study aimed to explore if natural dizygotic (DZ) twinning is associated with earlier menopause and lower anti-Mullerian hormone (AMH) values. We investigated if advanced biological reproductive aging, which can be responsible for the multiple follicle growth in familial twinning, is similar to mechanisms that occur in normal ovarian aging, reflected by earlier menopause in mothers of DZ twins and lower levels of AMH. A total of 16 mothers of DZ twins enrolled with the Netherlands Twin Register (average age at first assessment: 35.9 +/- 3.0 years) and 14 control mothers (35.1 +/- 3 years) took part in a prospective study. Fifteen years after entry into the study, which included follicle-stimulating hormone (FSH) assessment, AMH was measured in stored serum samples and menopause status was evaluated. Average AMH levels were not significantly different between DZ twin mothers and controls (2.1 +/- 2.4 mu g/L vs. 1.9 +/- 1.9 mu g/L). Among the 16 mothers of twins, 7 had an elevated (FSH) value over 10 U/L at first assessment. Their AMH levels were lower than the nine twin mothers with normal FSH values: 0.6 +/- 0.4 versus 3.4 +/- 2.6 mu g/L (p = .01). Of the mothers of twins, eight mothers had entered menopause at the second assessment compared with only one control mother (p = .07). Thus, slightly more DZ mothers were in menopause than the control mothers, although this difference was not significant. The subgroup of DZ twin mothers who had an increased FSH concentration 15 years ago had a limited ovarian reserve as reflected by lower AMH levels. These data indicate that advanced ovarian aging can be a feature in familial DZ twinning, particularly with elevated early follicular phase FSH

GHG emissions of supply chains from different retail systems in Europe

An approach has been developed to collect data and measure energy use and GHG emissions from logistics activities for product supply chains. This approach has been used to assess the GHG efficiency of several supply chains of the same product marketed through different types of retail systems in Europe. The retail types considered are hyper and supermarkets, corner shops, open-air markets, producer's basket direct sale, farm shops and e-commerce; Their GHG efficiencies are quantified and compared for food products, considering whole supply chains from the farm gate where they are grown to the consumer's home. This supply chain efficiency approach highlights the importance of the various operations carried out within the supply chains, such as transport, warehousing, the shop itself, and even consumer behaviour for the last mile. While supermarkets in towns, shops included in a delivery system, or open air markets in town centre appears to be very efficient, rural area and independent shops with lower turnover are less favourable. Indeed, the outcomes of an online consumer survey show large differences amongst the GHG efficiency values for all these retail systems. Therefore, potential logistics choices for improving the supply chain performance could be identified

Regional Economic growth and accessibility: The case of the Netherlands

Shift-share is a popular, relatively easy to apply, tool in spatial analysis. Upon its initial development and use in the 1970s the literature has shown that serious drawbacks of the shift-share technique should be noted (e.g., lack of theoretical basis, sensitivity to level of aggregation). But several solutions have been proposed, and besides, when a technique is simple and apparently useful, it will be both widely used and heavily criticized. The aim of this paper was to apply a shift- share analysis for the labour volume and value added. This was done for 40 so-called COROP-regions in the Netherlands over several subperiods of the most recent decades (1973-1993). It was shown that the development over time of the three shift-share effects for labour volume and value added were much the same. This was not only shown by means of a Geographic Information System but also statistically proved. Other relationships between the outcomes of the shift-share analysis and a few, more or less, economic variables were investigated as well. And lastly, an interesting aspect was the course of the regional growth of value added and employment over time. This development was illustrated by using a concentration-coefficient.

Considerations on the Transverse Emittance of the Fixed-Target Beam in the SPS in the PS2 Era

The range of the acceptable transverse emittances the Fixed-Target beams delivered to the SPS in the PS2 era is determined based on acceptance and other beam dynamics considerations in the SPS