Inefficient Worker Turnover

This paper considers the efficiency properties of risk-neutral workers mobility decisions in an equilibrium model with search frictions, but no search externalities, when the rent accruing to a match is split through bargaining. Matches are ex ante homogeneous and their true productivity is learnt after the match is formed. It is shown that the efficiency of worker turnover depends on contract enforceability, and that in the absence of complete enforceability the equilibrium fails to be efficient. This is because without complete enforceability firms cannot credibly offer workers contracts that will guarantee them the entire future of all potential future matches.On-the-Job Search, Learning, Bargaining, contracts, Enforceability

Inefficient Worker Turnover

This paper considers the efficiency properties of risk-neutral workers’ mobility decisions in an equilibrium model with search frictions, but no search externalities, when the rent accruing to a match is split through bargaining. Matches are ex ante homogeneous and their true productivity is learnt after the match is formed. It is shown that the efficiency of worker turnover depends on contract enforceability, and that in the absence of complete enforceability the equilibrium fails to be efficient. This is because without complete enforceability firms cannot credibly offer workers contracts that will guarantee them the entire future of all potential future matches.On-the-Job Search; Learning; Bargaining; Contracts; Enforceability

Sound clocks and sonic relativity

Sound propagation within certain non-relativistic condensed matter models obeys a relativistic wave equation despite such systems admitting entirely non-relativistic descriptions. A natural question that arises upon consideration of this is, "do devices exist that will experience the relativity in these systems?" We describe a thought experiment in which 'acoustic observers' possess devices called sound clocks that can be connected to form chains. Careful investigation shows that appropriately constructed chains of stationary and moving sound clocks are perceived by observers on the other chain as undergoing the relativistic phenomena of length contraction and time dilation by the Lorentz factor, with c the speed of sound. Sound clocks within moving chains actually tick less frequently than stationary ones and must be separated by a shorter distance than when stationary to satisfy simultaneity conditions. Stationary sound clocks appear to be length contracted and time dilated to moving observers due to their misunderstanding of their own state of motion with respect to the laboratory. Observers restricted to using sound clocks describe a universe kinematically consistent with the theory of special relativity, despite the preferred frame of their universe in the laboratory. Such devices show promise in further probing analogue relativity models, for example in investigating phenomena that require careful consideration of the proper time elapsed for observers.Comment: (v2) consistent with published version; (v1) 15 pages, 9 figure

Organic farm incomes in England and Wales 2010/11 (OF 0373)

This report presents results of research on the financial performance of organic farms in the 2010/11 financial year (with 2009/10 data for reference. Carried out for the Department for Environment, Food and Rural Affairs (Defra), this research continues project OF0373. An analysis of the FBS/Defra Data Archive for 2010/11 found a total of 250 businesses with some organic land. To ensure the analysis undertakes a reasonable comparison of organic and conventional farms, the organic sample comprises holdings with at least 70% fully organic land (>=70% of UAA ha). Farms identified as “in-conversion” or those with less than 70% fully organic certified land were excluded from the analysis, providing a sample of 217 organic holdings. In total, data from 212 organic farms were suitable for inclusion in the analysis, as it was not possible to identify comparable conventional businesses for four organic farms, and one organic specialist pig farm was also not utilised (due to minimum sample size restrictions). The data was analysed as two samples; a full sample and an identical sample. The full sample analysis utilised data from all 212 organic farms and provides the best comparison of organic and comparable conventional farm income data in 2010/11, (2009/10 data is only provided for reference). The identical sample identifies year to year changes within systems, though the sample sizes are smaller as not all farms will be part of the FBS dataset for two years

On the Segmentation of Markets

This paper endogenizes the market structure of an economy with heterogeneous agents who want to form bilateral matches in the presence of search frictions and when utility is non-transferable. We depart from standard matching models where all agents are assumed to be in a unique meeting place by assuming the existence of infinitely many meeting places and allowing each agent to choose which meeting place to be in. The market is thus allowed to be segmented into dierent meeting places, and agents not only get to choose who to match with, but also who they meet with. We show that in equilibrium all market structures feature perfect segmentation where agents match with the rst person they meet. All these market structures have the same matching pattern, implying that the value of search to each agent is the same. Although perfect assortative matching cannot be obtained in equilibrium, the degree of assortativeness is nevertheless greater than in standard models.search, matching, segmentation, market structure

Spin-Cooling of the Motion of a Trapped Diamond

Observing and controlling macroscopic quantum systems has long been a driving force in research on quantum physics. In this endeavor, strong coupling between individual quantum systems and mechanical oscillators is being actively pursued. While both read-out of mechanical motion using coherent control of spin systems and single spin read-out using pristine oscillators have been demonstrated, temperature control of the motion of a macroscopic object using long-lived electronic spins has not been reported. Here, we observe both a spin-dependent torque and spin-cooling of the motion of a trapped microdiamond. Using a combination of microwave and laser excitation enables the spin of nitrogen-vacancy centers to act on the diamond orientation and to cool the diamond libration via a dynamical back-action. Further, driving the system in the non-linear regime, we demonstrate bistability and self-sustained coherent oscillations stimulated by the spin-mechanical coupling, which offers prospects for spin-driven generation of non-classical states of motion. Such a levitating diamond operated as a compass with controlled dissipation has implications in high-precision torque sensing, emulation of the spin-boson problem and probing of quantum phase transitions. In the single spin limit and employing ultra-pure nano-diamonds, it will allow quantum non-demolition read-out of the spin of nitrogen-vacancy centers under ambient conditions, deterministic entanglement between distant individual spins and matter-wave interferometry.Comment: New version with a calibration of angular resolution and sensitivity. Fig. 1 is also replaced to show an ODMR when the diamond is static to avoid spin-torque induced distortion

Weighted embedding theorems for radial Besov and Triebel-Lizorkin spaces

We study the continuity and compactness of embeddings for radial Besov and Triebel-Lizorkin spaces with weights in the Muckenhoupt class $A_\infty$. The main tool is a discretization in terms of an almost orthogonal wavelet expansion adapted to the radial situation

Arrow's theorem for weak orders

We characterize binary decision rules which are independent and strongly paretian,or independent and almost strongly paretian when the individual preferences and the collective preference are weak orders.Binary decision rule, lexicographic dictatorship