Superfluid and Mott Insulating shells of bosons in harmonically confined optical lattices

Weakly interacting atomic or molecular bosons in quantum degenerate regime and trapped in harmonically confined optical lattices, exhibit a wedding cake structure consisting of insulating (Mott) shells. It is shown that superfluid regions emerge between Mott shells as a result of fluctuations due to finite hopping. It is found that the order parameter equation in the superfluid regions is not of the Gross-Pitaeviskii type except near the insulator to superfluid boundaries. The excitation spectra in the Mott and superfluid regions are obtained, and it is shown that the superfluid shells posses low energy sound modes with spatially dependent sound velocity described by a local index of refraction directly related to the local superfluid density. Lastly, the Berezinskii-Kosterlitz-Thouless transition and vortex-antivortex pairs are discussed in thin (wide) superfluid shells (rings) limited by three (two) dimensional Mott regions.Comment: 11 pages, 9 figures

On the "Fake" Inferred Entanglement Associated with the Maximum Entropy Inference of Quantum States

The inference of entangled quantum states by recourse to the maximum entropy principle is considered in connection with the recently pointed out problem of fake inferred entanglement [R. Horodecki, {\it et al.}, Phys. Rev. A {\it 59} (1999) 1799]. We show that there are operators $\hat A$, both diagonal and non diagonal in the Bell basis, such that when the expectation value $$ is taken as prior information the problem of fake entanglement is not solved by adding a new constraint associated with the mean value of $\hat A^2$ (unlike what happens when the partial information is given by the expectation value of a Bell operator). The fake entanglement generated by the maximum entropy principle is also studied quantitatively by comparing the entanglement of formation of the inferred state with that of the original one.Comment: 25 Revtex pages, 5 Postscript figures, submitted to J. Phys. A (Math. Gen.

On two-dimensional surface attractors and repellers on 3-manifolds

We show that if $f: M^3\to M^3$ is an $A$-diffeomorphism with a surface two-dimensional attractor or repeller $\mathcal B$ and $M^2_ \mathcal B$ is a supporting surface for $\mathcal B$, then $\mathcal B = M^2_{\mathcal B}$ and there is $k\geq 1$ such that: 1) $M^2_{\mathcal B}$ is a union $M^2_1\cup...\cup M^2_k$ of disjoint tame surfaces such that every $M^2_i$ is homeomorphic to the 2-torus $T^2$. 2) the restriction of $f^k$ to $M^2_i$ $(i\in\{1,...,k\})$ is conjugate to Anosov automorphism of $T^2$

Detection of cannabinoids in hair after cosmetic application of hemp oil.

The detection of cannabis constituents and metabolites in hair is an established procedure to provide evidence of exposure to cannabis. We present the frst known evidence to suggest that applying hemp oil to hair, as cosmetic treatment, may result in the incorporation of Δ9-tetrahydrocannabinol (THC), cannabinol (CBN), cannabidiol (CBD) and in one instance, the metabolite 11-hydroxy-Δ9- tetrahydrocannabinol (THC-OH). 10 volunteers treated their head hair daily with commercially available hemp oil for a period of 6 weeks. Head hair samples were collected before and after the application period. Hair samples were washed with methanol and subjected to clean up via liquid/ liquid and solid phase extraction procedures, and then GC-MS/MS for the analysis of THC, CBN, CBD, THC-OH and THC-COOH. Application of hemp oil to hair resulted in the incorporation of one or more cannabis constituents in 89% of volunteers, and 33% of the group tested positive for the three major constituents, THC, CBN and CBD. One volunteer showed low levels of the metabolite THC-OH. We suggest that cosmetic use of hemp oil should be recorded when sampling head hair for analysis, and that the interpretative value of cannabinoid hair measurements from people reporting application of hemp oil is treated with caution in both criminology and public health

Using the Arts for Food Research and Dialogue

This Briefing Paper is intended to share ideas and learning arising from the authors’ experiences of using arts-based methods in food research and engagement, as well as to give some insights into the issues that arose from a workshop for academics and Civil Society Organisations (CSOs) developed by Brighton and Sussex Universities Food Network (BSUFN) and hosted by the Food Research Collaboration (FRC) in 2016. It examines the use of participatory and community-centred approaches to explore pressing food policy questions, as well as providing guidance on how to apply these methods in practice. It is intended to be relevant to academics, particularly those interested in using participatory action research methods, and CSOs working with community groups on food issues. The authors’ main interest is the way in which arts-based methods provide a set of tools which can reveal, and give voice to, perspectives on food issues which remain otherwise absent from research and policy debates. In the authors' experience, this happens either because community members are not asked for their views or because of the way in which much traditional/positivist/biomedical academic research is based around pre-determined research questions that do not provide adequate space for community members to explore and voice their own concerns. It could be said that to date, much food research has failed to meaningfully engage with the general public, both during the research process itself and in raising awareness and achieving changes in the food system, which the research evidence indicates needs to happen. The paper firstly outlines why food research is a necessary and important area of exploration. Following this it examines the development, lineage and underlying principles of participatory and arts-based methodologies as approaches to research. Three arts-based and participatory methods are then reviewed in greater detail: i. Photography and film ii. Drama, and iii. Collage. These three methods were the focus of the BSUFN/FRC workshop in 2016. For each of these three examples, theoretical and methodological implications and ethical issues are discussed, enabling readers to fully consider how and why they might apply these approaches. In reviewing these emerging and alternative approaches for engaging communities in research processes, this paper presents a consideration of ideas, narratives, positions and actions relating to food, research and knowledge construction. The authors believe this paper to be an important addition to debates around how arts based and participatory methods might improve the processes, impact and contribution of food research. The paper presents a collaborative effort between academics, researchers and civil society organisations (CSOs) all of whom are concerned with improving research, learning and engagement in relation to food. The paper concludes with recommendations and suggestions on how academics and CSOs might use these methods as part of their research and/or practice

Turbulent drag on a low-frequency vibrating grid in superfluid He-4 at very low temperatures

We present measurements of the dissipative turbulent drag on a vibrating grid in superfluid He-4 over a wide range of (low) frequencies. At high velocities, the dissipative drag is independent of frequency and is approximately the same as that measured in normal liquid He-4. We present measurements on a similar grid in superfluid He-3-B at low temperatures which shows an almost identical turbulent drag coefficient at low frequencies. However, the turbulent drag in He-3-B is substantially higher at higher frequencies. We also present measurements of the inertial drag coefficient for grid turbulence in He-4. The inertial drag coefficient is significantly reduced by turbulence in both superfluid and normal liquid He-4

MeV measurements of γ-ray bursts by CGRO-COMPTEL: Revised catalog

The imaging COMPTEL telescope has accumulated 0.1–30 MeV spectra, time-histories, and positions of more than forty γ-ray bursts within its ∼3 sr field of view in the eight years since its launch. CGRO-COMPTEL measures in both imaging “telescope” and single detector “burst spectroscopy” mode. In an ongoing collaboration with BACODINE/GCN, bursts are imaged automatically, with localizations relayed to a global network of multiwavelength observers in near real time (∼10 minutes). We have updated our burst search procedure in two ways: 1) using more sensitive search algorithms; and 2) using data from more detectors. The first are double change-point algorithms. With these we can find regions of significant excess flux with no assumptions on the wide range of burst time-scales (e.g., rise-times or decay-times) or intensities, and only one adjustable parameter (the time-averaged count-rate of the detectors). This makes it simpler to combine information on burst time-histories from the larger effective area (but cruder time bins) burst spectroscopy detectors, and hence better pinpoint the best times for imaging each burst. We report the eight bursts detected during 1998–1999

Spectra of a recent bright burst measured by CGRO-COMPTEL: GRB 990123

CGRO-COMPTEL measures gamma-ray burst positions, time-histories and spectra in the 0.1–30 MeV energy range, in both imaging “telescope” and single detector “burst spectroscopy” mode. GRB 990123, one of the most recent bright bursts seen by COMPTEL, was caught in the optical while the gamma-ray emission was ongoing. The burst spectral shape can be characterized by a peak in ν−Fν just below 1 MeV and a power-law tail above(photon index∼−2.4,) and flattening below. There is also spectral evolution by downward movement of the peak and/or softening of the power laws. We present light-curves, time resolved spectra and an image map for this burst

Use of the EPIC model to predict runoff transport of surface-applied inorganic fertilizer and poultry manure constituents

The Erosion Productivity Impact Calculator (EPIC) model was applied to four fields established in 'tall' fescue (Festuca arundinacea Schreb.) in northwestern Arkansas to predict runoff and transport of nitrogen, phosphorus, and sediment. Fertilizer form varied among the fields with two receiving inorganic fertilizer, one receiving poultry (Gallus gallus domesticus) litter, and one receiving poultry manure. Soil and grazing parameters also differed among fields. Runoff and nutrient/sediment transport observed over 20 months were compared to EPIC predictions generated without calibration. Significant correlation between event predictions and observations were found in half the cases. There was significant correlation between observed and predicted calendar year total transport for all outputs except nitrate-nitrogen. The findings indicate that EPIC can accurately reflect runoff quality trends when executed without calibration for pasture fields in northwestern Arkansas