Coherence in a cold atom photon transistor

Recent experiments have realized an all-optical photon transistor using a cold atomic gas. This approach relies on electromagnetically induced transparency (EIT) in conjunction with the strong interaction among atoms excited to high-lying Rydberg states. The transistor is gated via a so-called Rydberg spinwave, in which a single Rydberg excitation is coherently shared by the whole ensemble. In its absence the incoming photon passes through the atomic ensemble by virtue of EIT while in its presence the photon is scattered rendering the atomic gas opaque. An important current challenge is to preserve the coherence of the Rydberg spinwave during the operation of the transistor, which would enable for example its coherent optical read-out and its further processing in quantum circuits. With a combined field theoretical and quantum jump approach and by employing a simple model description we investigate systematically and comprehensively how the coherence of the Rydberg spinwave is affected by photon scattering. With large-scale numerical calculations we show how coherence becomes increasingly protected with growing interatomic interaction strength. For the strongly interacting limit we derive analytical expressions for the spinwave fidelity as a function of the optical depth and bandwidth of the incoming photon

Decay of Escherichia Coli in Biosolids Applied to Agricultural Soil

There is little scientific data available on the survival patterns of pathogenic microorganisms introduced into the soil through the broad acre application of biosolids. This study was conducted to investigate the decay rates of Escherichia coli in agricultural soil amended with biosolids during two different growing seasons in a dry temperature cropping region in Western Australia.Biosolids-amended and unamended soil were inoculated with E. coli (ACM 1803), inserted into sentinel chambers and placed into the topsoil (0-10 cm) of a wheat crop. Biosolids were applied to designated biosolids plots, according to normal district practice, and E. coli numbers within the sentinel chambers were monitored over time. E. coli numbers in biosolids-amended soil reached detection limits (>10 cfu/mL) within 6 to 7 months. The decay patterns of E. coli, by treatment difference (biosolids-amended or unamended), linear and quadratic relationships of sampling time, and their interactions were highly significant. The T90 or time taken for a 90% reduction in numbers in the biosolids-amended soil was estimated to be 74, 143, 183 days (2006) and 173, 211 days (2008) as compared with 188 days (2006) and 156, 242 days (2008) in the unamended soil. This research provides scientific data on the survival times of E. coli in agricultural soil, with and without biosolids and can thus be helpful to public health policy

Decay of human enteric pathogens in agricultural soil amended with biosolids: Key findings from a comprehensive research project to examine potential health risks.

A comprehensive study was undertaken to examine the survival potential of enteric microorganisms in biosolids-amended soil, wheat plant phyllosphere, and stored grains. The presence of these microorganisms in the dust at harvesting time was also evaluated. In situ field experiments were conducted to examine the decay of E. coli (indicator bacteria), Salmonella enterica, bacteriophage MS2 and human adenovirus in biosolids-amended soils and in dust generated during harvesting of wheat. Glasshouse experiments were conducted to determine the survival potential of enteric microorganisms in the wheat phyllosphere and stored grains to determine any possible risks to humans or livestock through consumption of contaminated grains or fodder. The results of this study suggest that the target microorganisms decayed faster in the biosolids-amended soil compared with the unamended soil in the field, that the decay times were specific to the microorganism type; and that microorganism decay was correlated to declining soil moisture levels and increasing soil temperature. The risk of transmission of disease-causing microorganisms (human pathogens) from cereal crops fertilised with biosolids was considered to be low

Low-Voltage Continuous Electrospinning Patterning

Electrospinning is a versatile technique for the construction of microfibrous and nanofibrous structures with considerable potential in applications ranging from textile manufacturing to tissue engineering scaffolds. In the simplest form, electrospinning uses a high voltage of tens of thousands volts to draw out ultrafine polymer fibers over a large distance. However, the high voltage limits the flexible combination of material selection, deposition substrate, and control of patterns. Prior studies show that by performing electrospinning with a well-defined "near-field" condition, the operation voltage can be decreased to the kilovolt range, and further enable more precise patterning of fibril structures on a planar surface. In this work, by using solution dependent "initiators", we demonstrate a further lowering of voltage with an ultralow voltage continuous electrospinning patterning (LEP) technique, which reduces the applied voltage threshold to as low as 50 V, simultaneously permitting direct fiber patterning. The versatility of LEP is shown using a wide range of combination of polymer and solvent systems for thermoplastics and biopolymers. Novel functionalities are also incorporated when a low voltage mode is used in place of a high voltage mode, such as direct printing of living bacteria; the construction of suspended single fibers and membrane networks. The LEP technique reported here should open up new avenues in the patterning of bioelements and free-form nano- to microscale fibrous structures.Studentship and scholarship funding supports from the China Scholarship Council scholarship, EPSRC doctoral training partnership, Schlumberger Foundation, WD Armstrong Trus

CPTCPT Violating Electrodynamics and Chern-Simons Modified Gravity

The electrodynamics with a Chern-Simons term $p_{\mu}A_{\nu}\widetilde{F}^{\mu\nu}$ violates Lorentz and $CPT$ symmetries with a non-vanishing $p_{\mu}$. For a fixed vector $p_{\mu}$, in this paper we point out that the energy-momentum tensor of this theory coupled to the gravity minimally is symmetric but not divergence free, which consequently makes the gravitational field equation inconsistent. To preserve the consistency, we introduce a Chern-Simons term in the gravity sector with the coefficient determined by the Lorentz and $CPT$ violating term in the electromagnetic field. Further we study the phenomenologies of the model on the cosmic microwave background radiation and the relic gravitational waves.Comment: 11 pages, 1 figure, the version to appear in Physics Letters

Plant species with extremely small populations (PSESP) in China: A seed and spore biology perspective

AbstractApproximately one fifth of the world's plants are at risk of extinction. Of these, a significant number exist as populations of few individuals, with limited distribution ranges and under enormous pressure due to habitat destruction. In China, these most-at-risk species are described as ‘plant species with extremely small populations’ (PSESP). Implementing conservation action for such listed species is urgent. Storing seeds is one of the main means of ex situ conservation for flowering plants. Spore storage could provide a simple and economical method for fern ex situ conservation. Seed and spore germination in nature is a critical step in species regeneration and thus in situ conservation. But what is known about the seed and spore biology (storage and germination) of at-risk species? We have used China's PSESP (the first group listing) as a case study to understand the gaps in knowledge on propagule biology of threatened plant species. We found that whilst germination information is available for 28 species (23% of PSESP), storage characteristics are only known for 8% of PSESP (10 species). Moreover, we estimate that 60% of the listed species may require cryopreservation for long-term storage. We conclude that comparative biology studies are urgently needed on the world's most threatened taxa so that conservation action can progress beyond species listing

Attention-based High-order Feature Interactions to Enhance the Recommender System for Web-based Knowledge-Sharing Servic

Providing personalized online learning services has become a hot research topic. Online knowledge-sharing services represents a popular approach to enable learners to use fragmented spare time. User asks and answers questions in the platform, and the platform also recommends relevant questions to users based on their learning interested and context. However, in the big data era, information overload is a challenge, as both online learners and learning resources are embedded in data rich environment. Offering such web services requires an intelligent recommender system to automatically filter out irrelevant information, mine underling user preference, and distil latent information. Such a recommender system needs to be able to mine complex latent information, distinguish differences between users efficiently. In this study, we refine a recommender system of a prior work for web-based knowledge sharing. The system utilizes attention-based mechanisms and involves high-order feature interactions. Our experimental results show that the system outperforms known benchmarks and has great potential to be used for the web-based learning service

Behaviors that Predict Personality Components in Adult free-Ranging Tibetan Macaques (Macaca thibetana)

To further the potential for applied personality studies, we present a methodology for assessing personality in nonhuman animals without a priori assumptions, using behavioral measures to discriminate personality survey results. Our study group consisted of 12 free-ranging, provisioned, adult Tibetan macaques (Macaca thibetana) at the Valley of the Wild Monkeys, China. We asked familiar Chinese park guards and scientists to rate each of the 12 macaques using 27-item personality surveys. We also recorded behavioral observations (\u3e 100 hrs) from August–September, 2012. The personality surveys showed reliability in 22 of the items that were then utilized in a principal component analysis that revealed five components: Insecurity, Reactivity, Boldness, Sociability, and Leadership. Prior personality research on Macaca show comparable components. In order to determine which behaviors would best predict those five personality components, we conducted ­discriminant analyses using behavioral measures as predictors. We found that behavioral measures of avoidance, lunging, fear-grinning, self-directed behaviors, touching, proximity and chasing could significantly predict personality component scores in certain situations. Finally, we analyzed the effects of situation (provisioning and tourists) and found situation influenced proximity and rates of avoidance and self-directed behaviors. Wider implementation of this methodology may permit long-term analysis of personality using behavioral proxies for established personality traits, in particular on research investigating the effects of tourism and provisioning on personality