Conditional preparation of states containing a definite number of photons

A technique for conditionally creating single- or multimode photon-number states is analyzed using Bayesian theory. We consider the heralded N-photon states created from the photons produced by an unseeded optical parametric amplifier when the heralding detector is the time-multiplexed photon-number-resolving detector recently demonstrated by Fitch, et al. [Phys. Rev. A 68, 043814 (2003).] and simultaneously by Achilles, et al. [Opt. Lett. 28, 2387 (2003).]. We find that even with significant loss in the heralding detector, fields with sub-Poissonian photon-number distributions can be created. We also show that heralded multimode fields created using this technique are more robust against detector loss than are single-mode fields.Comment: 6 pages, 6 figures, reference added, typos corrected, content update

Randomization in substance abuse clinical trials

BACKGROUND: A well designed randomized clinical trial rates as the highest level of evidence for a particular intervention's efficacy. Randomization, a fundamental feature of clinical trials design, is a process invoking the use of probability to assign treatment interventions to patients. In general, randomization techniques pursue the goal of providing objectivity to the assignment of treatments, while at the same time balancing for treatment assignment totals and covariate distributions. Numerous randomization techniques, each with varying properties of randomness and balance, are suggested in the statistical literature. This paper reviews common randomization techniques often used in substance abuse research and an application from a National Institute on Drug Abuse (NIDA)-funded clinical trial in substance abuse is used to illustrate several choices an investigator faces when designing a clinical trial. RESULTS: Comparisons and contrasts of randomization schemes are provided with respect to deterministic and balancing properties. Specifically, Monte Carlo simulation is used to explore the balancing nature of randomization techniques for moderately sized clinical trials. Results demonstrate large treatment imbalance for complete randomization with less imbalance for the urn or adaptive scheme. The urn and adaptive randomization methods display smaller treatment imbalance as demonstrated by the low variability of treatment allocation imbalance. For all randomization schemes, covariate imbalance between treatment arms was small with little variation between adaptive schemes, stratified schemes and unstratified schemes given that sample sizes were moderate to large. CONCLUSION: We develop this paper with the goal of reminding substance abuse researchers of the broad array of randomization options available for clinical trial designs. There may be too quick a tendency for substance abuse researchers to implement the fashionable urn randomization schemes and other highly adaptive designs. In many instances, simple or blocked randomization with stratification on a major covariate or two will accomplish the same objectives as an urn or adaptive design, and it can do so with more simply implemented schedules and without the dangers of overmatching. Furthermore, the proper analysis, fully accounting for the stratified design, can be conducted

Novel Pressure Induced Structural Phase Transition in AgSbTe2_{2}

We report a novel high pressure structural sequence for the functionally graded thermoelectric, narrow band gap semiconductor AgSbTe$_{2}$, using angle dispersive x-ray diffraction in a diamond anvil cell with synchrotron radiation at room temperature. The compound undergoes a B1 to B2 transition; the transition proceeds through an intermediate amorphous phase found between 17-26 GPa that is quenchable down to ambient conditions. The pressure induced structural transition observed in this compound is the first of its type reported in this ternary cubic family, and it is new for the B1-B2 transition pathway reported to date. Density Functional Theory (DFT) calculations performed for the B1 and B2 phases are in good agreement with the experimental results.Comment: 4 pages, 3 figure

Scenario Analysis: Risk and Return of Aluminium Tolerant Lucerne

Lucerne (Medicago sativa) yield is limited by aluminium stress associated with acid soils (Campbell et al. 1988; Scott et al. 2008). With the aid of transgenic technologies, the development of aluminium tolerant (Al Tol) lucerne is proposed. Modelled scenario analysis was conducted to explore the potential net benefits of Al Tol lucerne as part of a grazing system for a sheep production system in the high rainfall zone of south west Victoria

Wildlife and pollution: 2001-02 Annual Report

The Wildlife and Pollution contract covers a long-term monitoring programme, the Predatory Bird Monitoring Scheme (PBMS), that examines the levels of certain pollutants in selected wildlife species in Britain. The programme was started in the early 1960s, when there were serious concerns over the effects of organochlorine insecticides and organomercury fungicides on various species of birds and mammals. This early work demonstrated the effects of the organochlorines and eventually contributed to the ban on their use in the UK and abroad. The programme has subsequently assessed the success of these bans by measuring whether there has been a decline in the concentrations of organochlorine pesticides in the livers and eggs of predatory and freshwater fish-eating birds. Investigations have also been made into the levels of industrial polychlorinated biphenyls (PCBs), following their identification as pollutants in 1966. Mercury levels, derived from both agricultural and industrial sources, have also been tracked, although mercury concentrations were not measured in birds collected in 2001. In recent years, investigations have been made into the effects of the newest generation of rodenticides on barn owls Tyto alba. Northern gannet Morus bassanus eggs are also collected approximately biennially from two colonies and, when available, from other sites; eggs were last collected in 2000. This programme is now the longest-running of its kind anywhere in the world and the findings stimulate considerable interest internationally, as well as in Britain. Annual reports give an interim summary of results and every three years these annual results are gathered together into a more substantial report in which they are integrated with previous findings. The latest report of this type covers the period up to and including 2000 (Shore et al. 2005). Results are published periodically in the scientific literature. This current report presents the results of analyses carried out on material collected in 2001. It also includes a review of long-term trends in second-generation anticoagulant rodenticide residues in barn owls that occurred during the monitoring period up to and including the year 2001. The Wildlife and Pollution contract was the subject of scientific assessment within JNCC's rolling programme of peer review in autumn 1993 and was further assessed in 1996. As a result of the last two assessments, some monitoring was curtailed. Most notably, common kestrels Falco tinnunculus are no longer monitored for organochlorines. However, from 2001 onwards, kestrels will be monitored for second-generation anticoagulant rodenticides following the results from an individual study, carried out as part of the PBMS activities, which demonstrated that this species may be particularly vulnerable to exposure to these compounds (Shore et al. 2001). Carcasses and eggs of predatory bird species (such as peregrine falcon Falco peregrinus, common buzzard Buteo buteo, long-eared owl Asio otus, little owl Athene noctua, common kingfisher Alcedo atthis, great crested grebe Podiceps cristatus, and great bittern Botaurus stellaris) which do not form the core part of the PBMS, but are sent to the Centre for Ecology & Hydrology (CEH) by volunteers, are not analysed chemically. However, post-mortem examinations are carried out the carcasses, relevant information is recorded and the cause of death is determined (and reported back to the volunteer who submitted the carcass). Samples of the egg contents and body organs for these species, and samples for the species that do form part of the core monitoring, are all archived at -20°C as part of CEH's unique long-term tissue bank, and are often used in specific targeted research studies in subsequent years. Each section within the Wildlife and Pollution contract is summarised below. Each is dependent on the provision of material from amateur naturalists and other interested parties, and it is not always possible to obtain desired material for analysis, especially from remote areas

Wildlife and pollution: 2000-01 Annual Report

The Wildlife and Pollution contract covers a long-term monitoring programme that examines the levels of certain pollutants in selected wildlife species in Britain. The programme was started in the early 1960s, when there were serious concerns over the effects of organochlorine insecticides and organomercury fungicides on various species of birds and mammals. This early work demonstrated the effects of the organochlorines, and eventually contributed to the ban on their use in the UK and abroad. The programme has measured levels of these compounds in predatory and fish-eating birds since then. Investigations have also been made into the levels of industrial polychlorinated biphenyls (PCBs), following their identification as pollutants in 1966. Mercury levels, derived from both agricultural and industrial sources, have also been tracked. In recent years, investigations have been made into the effects of the latest generation of rodenticides on barn owls Tyto alba. Northern gannet Morus bassanus eggs are also collected approximately biennially from two colonies and, when available, from other sites; eggs were collected from one site in 2000. This programme is now the longest-running of its kind anywhere in the world and the findings stimulate considerable interest internationally, as well as in Britain. Annual reports give an interim summary of results. This current report presents the results of analyses carried out on material collected in 2000. Every three years these annual results are gathered together into a more substantial report in which they are integrated with previous findings. The last report of this type covered the period up to and including 1997 (Newton et al. 1998) and is updated here. The present report summarises the long-term trends in all contaminants (except rodenticides, analysed in Shore et al. 2005) that occurred during the monitoring period up to and including the year 2000. Results are published periodically in the scientific literature, and recent key papers are listed in the references to the present report. The Wildlife and Pollution contract was the subject of scientific assessment within JNCC's rolling programme of peer review in autumn 1993 and was further assessed in 1996. As a result of the last two assessments, some monitoring was curtailed. Specifically, common kestrels Falco tinnunculus were no longer monitored for organochlorines, although from 2001 this species will be monitored annually for second-generation anticoagulant rodenticides. The Centre for Ecology & Hydrology (CEH) still collects specimens for studying other contaminants as part of its core research programme. Similarly, other species (peregrine falcon Falco peregrinus, common buzzard Buteo buteo, long-eared owl Asio otus, little owl Athene noctua, common kingfisher Alcedo atthis, great crested grebe Podiceps cristatus, and great bittern Botaurus stellaris) that were received in small numbers in occasional years were also not analysed routinely, although some were analysed in specific one-off studies and tissues from all birds received at CEH in 2000 are archived in deep-freeze for future potential analyses. Each section within the Wildlife and Pollution contract is summarised below. Each is dependent on the provision of material from amateur naturalists and other interested parties, and it is not always possible to obtain desired material for analysis, especially from remote areas

Inflation without Inflaton(s)

We propose a model for early universe cosmology without the need for fundamental scalar fields. Cosmic acceleration and phenomenologically viable reheating of the universe results from a series of energy transitions, where during each transition vacuum energy is converted to thermal radiation. We show that this `cascading universe' can lead to successful generation of adiabatic density fluctuations and an observable gravity wave spectrum in some cases, where in the simplest case it reproduces a spectrum similar to slow-roll models of inflation. We also find the model provides a reasonable reheating temperature after inflation ends. This type of model may also be relevant for addressing the smallness of the vacuum energy today.Comment: 13 pages, 4 figures, published versio