Observation of vortex dipoles in an oblate Bose-Einstein condensate

We report experimental observations and numerical simulations of the formation, dynamics, and lifetimes of single and multiply charged quantized vortex dipoles in highly oblate dilute-gas Bose-Einstein condensates (BECs). We nucleate pairs of vortices of opposite charge (vortex dipoles) by forcing superfluid flow around a repulsive gaussian obstacle within the BEC. By controlling the flow velocity we determine the critical velocity for the nucleation of a single vortex dipole, with excellent agreement between experimental and numerical results. We present measurements of vortex dipole dynamics, finding that the vortex cores of opposite charge can exist for many seconds and that annihilation is inhibited in our highly oblate trap geometry. For sufficiently rapid flow velocities we find that clusters of like-charge vortices aggregate into long-lived dipolar flow structures.Comment: 4 pages, 4 figures, 1 EPAPS fil

The sovereign yield curve and credit ratings in GIIPS

© 2020 International Review of Finance Ltd. 2020 This paper studies the impact of sovereign credit rating and outlook changes on the shape of the sovereign yield curve using data for five European countries, namely, Greece, Ireland, Italy, Portugal, and Spain, known as the GIIPS for the period of 2001–2016. We use the dynamic Nelson–Siegel model to estimate the level, slope, and curvature of the yield curve. Subsequently, we employ the vector autoregressive model to estimate the effect of sovereign rating and outlook changes on the sovereign yield curve. We find a significant effect of rating downgrades and an insignificant effect of rating upgrades in all five countries; however, the results for the effect of changes in outlook status are mixed. Our results remain robust to various sensitivity tests

Blockchain-driven customer order management

Purpose The purpose of this paper is to investigate the effects of Blockchain on the customer order management process and operations. There is limited understanding of the use and benefits of Blockchain on supply chains, and less so at processes level. To date, there is no research on the effects of Blockchain in the customer order management process. Design/methodology/approach A twofold method is followed. First, a Blockchain is programmed and implemented in a large international firm. Second, a series of simulations are built based on three scenarios: current with no-Blockchain, 1-year and 5-year Blockchain use. Findings Blockchain improves the efficiency of the process: it reduces the number of operations, reduces the average time of orders in the system, reduces workload, shows traceability of orders and improves visibility to various supply chain participants. Research limitations/implications The research is based on a single in-depth case that has the scope to be tested in other contexts in future. Practical implications This is the first study that demonstrates with real data from an industrial firm the effects of Blockchain on the efficiency gains, reduction on the number of operations and human-processing savings. A detailed description of the Blockchain implementation is provided. Furthermore, this research shows a list of the resources and capabilities needed for building and maintaining a Blockchain in the context of supply chains. Originality/value This is the first study that demonstrates with real data from an industrial firm the effects of Blockchain on the efficiency gains, the reduction in the number of operations and human-processing savings. A detailed description of the Blockchain implementation is provided. This paper contributes to the resource-based view of the firm, by demonstrating two new competitive valuable capabilities and a new dynamic capability that organisations develop when implementing and using Blockchain in a supply–demand process. It also contributes to the information processing theory by highlighting the analytics capabilities required to sustain Blockchain-related operations. </jats:sec

Evalution of the Efficacy of the Photosystem II Inhibitor DCMU in Periphyton and Its Effects On Nontarget Microorganisms and Extracellular Enzymatic Reactions

We examined the efficacy of the photosystem II inhibitor 3-(3,4-diclorophenyl)-1,1-dimethyl urea (DCMU) for inhibition of algal photosynthesis in periphyton associated with submerged decomposing litter of Typha angustifolia. We also investigated the possible nontarget effects of DCMU exposure on heterotrophic microorganisms (i.e., bacteria and fungi) and extracellular enzyme activity associated with decaying litter. Standing-dead Typha leaf litter was submerged for 34 and 73 d, returned to the laboratory, and used for controlled laboratory experiments that examined the effect of DCMU on algal ([14C]bicarbonate, pulse-amplitude modulated fluorometry), bacterial ([3H]leucine), and fungal ([14C]acetate) production. Simultaneous assays also were conducted to examine the effect of DCMU on the activities of 4 extracellular enzymes (β-glucosidase, β-xylosidase, leucine-aminopeptidase, and phosphatase). DCMU significantly inhibited algal photosynthesis in light-exposed periphyton (p always \u3c 0.0003), with strong inhibitory effects occurring within 5 min after exposure to DCMU. In contrast, DCMU had no significant direct effect on bacterial (p \u3e 0.5) or fungal production (p \u3e 0.3). Extracellular enzyme activities also were not significantly affected by exposure to DCMU. Heterotrophic microbial and enzyme activity assays were conducted in darkness to avoid any indirect effects of DCMU (i.e., heterotrophic responses to the inhibition of photosynthesis, rather than to DCMU itself). The apparent lack of nontarget effects of DCMU on heterotrophic microbial processes, combined with good efficacy against algal photosynthesis, suggest that DCMU may a useful selective inhibitor for investigations of interactions among litter-inhabiting microbiota

Miscellaneous Fish Helminth Parasite (Trematoda, Cestoidea, Nematoda, Acanthocephala) Records from Arkansas

Between June 2012 and January 2014, 147 fishes (10 species) within five families were collected from watersheds in 8 counties of Arkansas and examined for helminth parasites. Almost every fish species examined harbored at least one or more helminth parasite, including 5 trematodes (Alloglossidium sp., Plagioporus sp., Crepidostomum sp., Clinostomum marginatum and unknown metacercaria), 2 cestodes (unknown cyclophyllidean cysticerci and Corallotaenia parva), 3 nematodes (Spiroxys sp., Capillaria catostomi, and Eustrongylides sp.), and 3 acanthocephalans (unknown cystacanths, Neoechinorhynchus sp., and Leptorhynchoides sp.). We document 16 new host and 2 new distributional records for these helminths. In addition, this is the first time any helminth has been reported from the Blackspot Shiner, Notropis atrocaudalis and Caddo Madtom, Noturus taylori

Phenotype standardization for statin-induced myotoxicity

Statins are widely used lipid-lowering drugs that are effective in reducing cardiovascular disease risk. Although they are generally well tolerated, they can cause muscle toxicity, which can lead to severe rhabdomyolysis. Research in this area has been hampered to some extent by the lack of standardized nomenclature and phenotypic definitions. We have used numerical and descriptive classifications and developed an algorithm to define statin-related myotoxicity phenotypes, including myalgia, myopathy, rhabdomyolysis, and necrotizing autoimmune myopathy.</p

Characteristics of Two-Dimensional Quantum Turbulence in a Compressible Superfluid

Under suitable forcing a fluid exhibits turbulence, with characteristics strongly affected by the fluid's confining geometry. Here we study two-dimensional quantum turbulence in a highly oblate Bose-Einstein condensate in an annular trap. As a compressible quantum fluid, this system affords a rich phenomenology, allowing coupling between vortex and acoustic energy. Small-scale stirring generates an experimentally observed disordered vortex distribution that evolves into large-scale flow in the form of a persistent current. Numerical simulation of the experiment reveals additional characteristics of two-dimensional quantum turbulence: spontaneous clustering of same-circulation vortices, and an incompressible energy spectrum with $k^{-5/3}$ dependence for low wavenumbers $k$ and $k^{-3}$ dependence for high $k$.Comment: 7 pages, 7 figures. Reference [29] updated for v