Investigating dark matter substructure with pulsar timing: I. Constraints on ultracompact minihalos

Small-scale dark matter structure within the Milky Way is expected to affect pulsar timing. The change in gravitational potential induced by a dark matter halo passing near the line of sight to a pulsar would produce a varying delay in the light travel time of photons from the pulsar. Individual transits produce an effect that would either be too rare or too weak to be detected in 30-year pulsar observations. However, a population of dark matter subhalos would be expected to produce a detectable effect on the measured properties of pulsars if the subhalos constitute a significant fraction of the total halo mass. The effect is to increase the dispersion of measured period derivatives across the pulsar population. By statistical analysis of the ATNF pulsar catalogue, we place an upper limit on this dispersion of $\log \sigma_{\dot{P}} \leq -17.05$. We use this to place strong upper limits on the number density of ultracompact minihalos within the Milky Way. These limits are completely independent of the particle nature of dark matter.Comment: 9 pages, 5 figues, includes erratum published in MNRA

Heating of galactic gas by dark matter annihilation in ultracompact minihalos

The existence of substructure in halos of annihilating dark matter would be expected to substantially boost the rate at which annihilation occurs. Ultracompact minihalos of dark matter (UCMHs) are one of the more extreme examples of this. The boosted annihilation can inject significant amounts of energy into the gas of a galaxy over its lifetime. Here we determine the impact of the boost factor from UCMH substructure on the heating of galactic gas in a Milky Way-type galaxy, by means of N-body simulation. If $1\%$ of the dark matter exists as UCMHs, the corresponding boost factor can be of order $10^5$. For reasonable values of the relevant parameters (annihilation cross section $3\times10^{-26} ~\textrm{cm}^3~ \textrm{s}^{-1}$, dark matter mass 100 GeV, 10% heating efficiency), we show that the presence of UCMHs at the 0.1% level would inject enough energy to eject significant amounts of gas from the halo, potentially preventing star formation within $\sim$1 kpc of the halo centre.Comment: 14 pages, 3 figure

A Theory of Claim Resolution

We study claim resolution. A claim consists of a global fact and a local fact. The global fact is observed by the principal and the agent. The local fact is observed by the agent alone. The agent resolves the claim; the principal decides whether the agent is more likely wrong or right. The principal and agent can disagree about the weight to accord each fact or the overall evidence threshold. The agent cares whether the principal follows or ignores her advice. We characterize how the equilibrium varies with the nature of disagreement. Despite lacking commitment power, we nd that the principal grants the agent decision-making authority over an interval of global facts

THE COST OF FORWARD CONTRACTING

The cost of forward contracting corn is estimated with weekly pre-harvest forward bases for seven regions of Illinois from 1975 to 2002. Given the panel structure of the forward basis dataset, we extend Townsend and Brorsen's univariate unit root model for forward bases to a panel unit root model. With the time series of forward bases modeled as unit root processes, the cost of forward contracting is estimated. The empirical results from the estimation show that the cost of forward contracting corn is about 1¢/bushel, one hundred days before the harvest, for all regions in Illinois as a whole. The results also indicates that the cost could vary across regions and that the cost of forward contracting could be substantially higher than that of futures hedging, especially at the beginning of the pre-harvest period.Marketing,

The Pricing Performance of Market Advisory Services in Corn and Soybeans Over 1995-2003: A Non-Technical Summary

The purpose of this research report is to summarize the pricing performance of professional market advisory services for the 1995-2003 corn and soybean crops. First, advisory programs in corn do not consistently beat market benchmarks, but tend to consistently beat the farmer benchmark. Second, advisory programs in soybeans exhibit just the opposite pattern, consistently beating the market benchmarks but not the farmer benchmark. Third, in terms of 50/50 revenue, advisory programs show marginal consistency in beating both the market benchmarks and the farmer benchmark. So, the results provide mixed performance evidence with respect to both the market benchmarks and the farmer benchmark.Agricultural Finance,

The Pricing Performance of Market Advisory Services in Corn and Soybeans over 1995-2003

The purpose of this research report is to evaluate the pricing performance of market advisory services for the 1995-2003 corn and soybean crops. Four basic indicators of performance are applied to advisory program prices and revenues over 1995-2003. Test results provide little evidence that advisory programs as a group outperform market benchmarks, particularly after considering risk. The evidence is somewhat more positive with respect to the farmer benchmark, even after taking risk into account. For example, the average advisory return relative to the farmer benchmark is $7 per acre with only a negligible increase in risk. While this return is small it nonetheless represents a non-trivial increase in net farm income per acre for grain farms in Illinois. Test results also suggest that it is difficult to usefully predict the year-to-year pricing performance of advisory programs based on past pricing performance. However, there is some evidence that performance is more predictable over longer time horizons, particularly at the extremes of performance rankings.Marketing,

Top Tips for healthier providers of health-care in Merseyside and Cheshire

Top tips for healthier providers of health-care aims to support organisations in focusing on the actions they can take to improve the health their patients, their staff, and the wider community that they serve. It builds on a previous report that was carried out by Liverpool Public Health Observatory in 2006, which focused on hospitals. The report is a review of secondary data, alongside examples of local delivery from Merseyside and Cheshire

Rapid Health Impact Assessment for Royal Liverpool and Broadgreen University Hospitals Trust - ‘A New Health Service for Liverpool, World Class Hospitals, World Class Services’

The overall aim of this HIA was to maximise the health benefits, which could result from implementation of the proposals by the Royal Liverpool and Broadgreen Hospitals to redesign its services, develop a new hospital to replace the Royal Liverpool University Hospital (RLUH) on its existing site, and make further investment at Broadgreen Hospital. In order to do this, the following objectives had to be achieved; Identify and profile the population groups who will be affected by the proposal. Identify the potential positive and negative health impacts of the proposal and set out clearly who will be affected by these impacts. Make recommendations for the elimination or mitigation of negative impacts (or compensation for those affected). Make recommendations for the maximisation of positive impacts

Robustness, efficiency, and optimality in the Fenna-Matthews-Olson photosynthetic pigment-protein complex

Pigment-protein complexes (PPCs) play a central role in facilitating excitation energy transfer (EET) from light-harvesting antenna complexes to reaction centres in photosynthetic systems; understanding molecular organisation in these biological networks is key to developing better artificial light-harvesting systems. In this article, we combine quantum-mechanical simulations and a network-based picture of transport to investigate how chromophore organization and protein environment in PPCs impacts on EET efficiency and robustness. In a prototypical PPC model, the Fenna-Matthews-Olson (FMO) complex, we consider the impact on EET efficiency of both disrupting the chromophore network and changing the influence of (local and global) environmental dephasing. Surprisingly, we find a large degree of resilience to changes in both chromophore network and protein environmental dephasing, the extent of which is greater than previously observed; for example, FMO maintains EET when 50% of the constituent chromophores are removed, or when environmental dephasing fluctuations vary over two orders-of-magnitude relative to the in vivo system. We also highlight the fact that the influence of local dephasing can be strongly dependent on the characteristics of the EET network and the initial excitation; for example, initial excitations resulting in rapid coherent decay are generally insensitive to the environment, whereas the incoherent population decay observed following excitation at weakly coupled chromophores demonstrates a more pronounced dependence on dephasing rate as a result of the greater possibility of local exciton trapping. Finally, we show that the FMO electronic Hamiltonian is not particularly optimised for EET; instead, it is just one of many possible chromophore organisations which demonstrate a good level of EET transport efficiency following excitation at different chromophores. Overall, these robustness and efficiency characteristics are attributed to the highly connected nature of the chromophore network and the presence of multiple EET pathways, features which might easily be built into artificial photosynthetic systems