Entanglement Cost of Nonlocal Measurements

For certain joint measurements on a pair of spatially separated particles, we ask how much entanglement is needed to carry out the measurement exactly. For a class of orthogonal measurements on two qubits with partially entangled eigenstates, we present upper and lower bounds on the entanglement cost. The upper bound is based on a recent result by D. Berry [Phys. Rev. A 75, 032349 (2007)]. The lower bound, based on the entanglement production capacity of the measurement, implies that for almost all measurements in the class we consider, the entanglement required to perform the measurement is strictly greater than the average entanglement of its eigenstates. On the other hand, we show that for any complete measurement in d x d dimensions that is invariant under all local Pauli operations, the cost of the measurement is exactly equal to the average entanglement of the states associated with the outcomes.Comment: 14 pages; new result in v4: cost of an arbitrary measurement invariant under local Pauli operation

Primary neurons that express the L2/HNK-1 carbohydrate during early development in the zebrafish

In zebrafish, many nerve pathways in both the CNS and periphery are pioneered by a small and relatively simple set of ‘primary’ neurons that arise in the early embryo. We now have used monoclonal antibodies to show that, as they develop, primary neurons of several functional classes express on their surfaces the L2/HNK-1 tetrasaccharide that is associated with a variety of cell surface adhesion molecules. We have studied the early labeling patterns of these neurons, as well as some non-neural cells, and found that the time of onset and intensity of immunolabeling vary specifically according to cell type. The first neuronal expression is by Rohon-Beard and trigeminal ganglion neurons, both of which are primary sensory neurons that mediate touch sensitivity. These cells express the epitope very strongly on their growth cones and axons, permitting study of their development unobscured by labeling in other cells. Both types initiate axogenesis at the same early time, and appear to be the first neurons in the embryo to do so. Their peripheral neurites display similar branching patterns and have similar distinctive growth cone morphologies. Their central axons grow at the same rate along the same longitudinal fiber pathway, but in opposite directions, and where they meet they appear to fasciculate with one another. The similarities suggest that Rohon-Beard and trigeminal ganglion neurons, despite their different positions, share a common program of early development. Immunolabeling is also specifically present on a region of the brain surface where the newly arriving trigeminal sensory axons will enter the brain. Further, the trigeminal expression of the antigen persists in growth cones during the time that they contact an individually identified central target neuron, the Mauthner cell, which also expresses the epitope. These findings provide descriptive evidence for possible roles of L2/HNK-1 immunoreactive molecules in axonal growth and synaptogenesis

The origin of ultra diffuse galaxies: stellar feedback and quenching

We test if the cosmological zoom-in simulations of isolated galaxies from the FIRE project reproduce the properties of ultra diffuse galaxies. We show that stellar feedback-generated outflows that dynamically heat galactic stars, together with a passively aging stellar population after imposed quenching (from e.g. infall into a galaxy cluster), naturally reproduce the observed population of red UDGs, without the need for high spin halos or dynamical influence from their host cluster. We reproduce the range of surface brightness, radius and absolute magnitude of the observed z=0 red UDGs by quenching simulated galaxies at a range of different times. They represent a mostly uniform population of dark matter-dominated galaxies with M_star ~1e8 Msun, low metallicity and a broad range of ages. The most massive simulated UDGs require earliest quenching and are therefore the oldest. Our simulations provide a good match to the central enclosed masses and the velocity dispersions of the observed UDGs (20-50 km/s). The enclosed masses of the simulated UDGs remain largely fixed across a broad range of quenching times because the central regions of their dark matter halos complete their growth early. A typical UDG forms in a dwarf halo mass range of Mh~4e10-1e11 Msun. The most massive red UDG in our sample requires quenching at z~3 when its halo reached Mh ~ 1e11 Msun. If it, instead, continues growing in the field, by z=0 its halo mass reaches > 5e11 Msun, comparable to the halo of an L* galaxy. If our simulated dwarfs are not quenched, they evolve into bluer low-surface brightness galaxies with mass-to-light ratios similar to observed field dwarfs. While our simulation sample covers a limited range of formation histories and halo masses, we predict that UDG is a common, and perhaps even dominant, galaxy type around Ms~1e8 Msun, both in the field and in clusters.Comment: 20 pages, 13 figures; match the MNRAS accepted versio

Quickest Paths in Simulations of Pedestrians

This contribution proposes a method to make agents in a microscopic simulation of pedestrian traffic walk approximately along a path of estimated minimal remaining travel time to their destination. Usually models of pedestrian dynamics are (implicitly) built on the assumption that pedestrians walk along the shortest path. Model elements formulated to make pedestrians locally avoid collisions and intrusion into personal space do not produce motion on quickest paths. Therefore a special model element is needed, if one wants to model and simulate pedestrians for whom travel time matters most (e.g. travelers in a station hall who are late for a train). Here such a model element is proposed, discussed and used within the Social Force Model.Comment: revised version submitte

The effects of temperature on Bosmina longirostris susceptibility to microcystin-LR acute toxicity

Harmful algal blooms are an ongoing threat to many aquatic systems throughout the world. In the Chowan River, North Carolina, the frequency of toxin producing Microcystis aeruginosa blooms has increased since 1975 along with an average 0.71°C rise in water temperature. The combined effect of microcystin-LR toxin and rising temperatures on a dominant zooplankter in the system, Bosmina longirostris, was the focus of this study. Laboratory studies were conducted to determine how microcystin-LR, produced from M. aeruginosa blooms, affected B. longirostris mortality under different temperature regimes. At 25°C, the LC50 for B. longirostris was 26.3 μg L-1 suggesting that B. longirostris can survive typical current bloom microcystin-LR concentrations ranging 0.1μg L-1 to 2.0 μg L-1, but would be susceptible to higher concentrations they may be periodically exposed to. Mortality was assessed at a constant microcystin-LR concentration of 26.3 μg L-1 over 15–35°C, and it was found that B. longirostris mortality increased at higher temperatures. B. longirostris mortality increased approximately 18% due to microcystin-LR alone over 2°C between 25°C and 27°C when exposed to the LC50 concentration. The increased prevalence of toxic M. aeruginosa blooms and increasing temperatures due to climate change may reduce B. longirostris populations, potentially affecting larval fish and fisheries in the Chowan River, North Carolina

Josephson Coupling through a Quantum Dot

We derive, via fourth order perturbation theory, an expression for the Josephson current through a gated interacting quantum dot. We analyze our expression for two different models of the superconductor-dot-superconductor (SDS) system. When the matrix elements connecting dot and leads are featureless constants, we compute the Josephson coupling J_c as a function of the gate voltage and Coulomb interaction. In the diffusive dot limit, we compute the probability distribution P(J_c) of Josephson couplings. In both cases, pi junction behavior (J_c < 0) is possible, and is not simply dependent on the parity of the dot occupancy.Comment: 9 pages; 3 encapsulated PostScript figure

Production of Astaxanthin Using Modified E. coli Cells

There are several promising markets for naturally synthesized Astaxanthin, a carotenoid found in krill, shrimp, salmon, and other marine life that imparts to these creatures a pink coloring of the flesh and has demonstrated human health-promoting anti-inflammatory and antioxidant activity. Compared to Astaxanthin produced through chemical synthesis, Astaxanthin synthesized through natural fermentative processes (in yeast and algae) is esterified, imparting greater antioxidant activity as well as bioavailability and making it the preferred ingredient for nutraceutical formulations. Additionally, as consumer preferences trend toward natural production processes free from the use of petrochemical solvents which may pose hazards to health hazards, fermentative production coupled with an extraction process featuring more environment- and health-friendly solvents is desired. Recently, a strain of E.coli has been genetically optimized to produce Astaxanthin, offering a cheaper synthesis route compared with algal cultivation. Herein, the authors propose a process for the production of natural Astaxanthin through fermentation in genetically modified E.coli and recovery of the compound from biomass via supercritical CO2 extraction. The fermentation seed train is composed of three pre-seed, two seed, and three production fed-batch fermenters. Biomass from the production stage is collected in a harvest/surge tank for continuous downstream processing. The biomass is concentrated in broth, the cells are lysed, and the slurry of lysed cells are dried. The lysis product is loaded with fructose and diatomaceous earth in order to produce biomass pellets that are appropriate for the extraction phase. Supercritical CO2 with ethanol co-solvent is used to extract Astaxanthin from these pellets. Astaxanthin is heat-sensitive and has low accumulation in cells. Despite the expensive equipment necessary to preserve the structure and activity of the product and the low yearly production rate, the high selling price of Astaxanthin makes this process economically profitable, with an investor’s rate of return of 125%, net present value of $468 million, and return on investment of 171%

Dispositions in the Twenty First Century School Library Profession

Within the school library profession there is an emerging focus on dispositions, defined as a tendency to exhibit frequently, consciously, and voluntarily a pattern of behavior that is directed to a broad goal (Katz, 1993). Directed focus groups of practicing school librarians were asked to articulate their vision for school libraries of the future. Data from these groups informed development of six dispositional continua to guide both school library education and school librarianship in the 21st century. This study clarifies the dispositions needed by school librarians in the future

Culturally Relevant Booktalking: Using a Mixed Reality Simulation With Preservice School Librarians

The role of school librarians is often overlooked in advancing a respect for cultural diversity among youth, yet librarians are in key positions to champion for social justice reform in educational settings. In this qualitative study, we examine preservice school librarians\u27 experiences with booktalking multicultural literature in a mixed reality simulation environment, as a vehicle to introduce social justice issues. Our purpose was to explore the booktalking experience as a means of developing preservice librarians\u27 understanding of culturally relevant pedagogy, a stance concerned with developing cultural competence and critical consciousness. Our findings revealed that preservice librarians gained different levels of understanding of culturally relevant pedagogy yet, the experience provided them with an opportunity for engaging in critical reflection regarding personal bias and systemic racism in schools and literature