1,049 research outputs found
Quantum walks on two-dimensional grids with multiple marked locations
The running time of a quantum walk search algorithm depends on both the
structure of the search space (graph) and the configuration of marked
locations. While the first dependence have been studied in a number of papers,
the second dependence remains mostly unstudied.
We study search by quantum walks on two-dimensional grid using the algorithm
of Ambainis, Kempe and Rivosh [AKR05]. The original paper analyses one and two
marked location cases only. We move beyond two marked locations and study the
behaviour of the algorithm for an arbitrary configuration of marked locations.
In this paper we prove two results showing the importance of how the marked
locations are arranged. First, we present two placements of marked
locations for which the number of steps of the algorithm differs by
factor. Second, we present two configurations of and
marked locations having the same number of steps and probability to
find a marked location
Quantum search by continuous-time quantum walk on t-designs
This work examines the time complexity of quantum search algorithms on
combinatorial -designs with multiple marked elements using the
continuous-time quantum walk. Through a detailed exploration of -designs and
their incidence matrices, we identify a subset of bipartite graphs that are
conducive to success compared to random-walk-based search algorithms. These
graphs have adjacency matrices with eigenvalues and eigenvectors that can be
determined algebraically and are also suitable for analysis in the
multiple-marked vertex scenario. We show that the continuous-time quantum walk
on certain symmetric -designs achieves an optimal running time of
, where is the number of points and blocks, even when
accounting for an arbitrary number of marked elements. Upon examining two
primary configurations of marked elements distributions, we observe that the
success probability is consistently , but it approaches 1 asymptotically
in certain scenarios.Comment: 15 page
Inhomogeneous freeze-out in relativistic heavy-ion collisions
A QCD phase transition may reflect in a inhomogeneous decoupling surface of
hadrons produced in relativistic heavy-ion collisions. We show that due to the
non-linear dependence of the particle densities on the temperature and
baryon-chemical potential such inhomogeneities should be visible even in the
integrated, inclusive abundances. We analyze experimental data from Pb+Pb
collisions at CERN-SPS and Au+Au collisions at BNL-RHIC to determine the
amplitude of inhomogeneities.Comment: 8 pages, 5 figure
Tissue-nonspecific alkaline phosphatase promotes axonal growth of hippocampal neurons
Axonal growth is essential for establishing neuronal circuits during brain development and for regenerative processes in the adult brain. Unfortunately, the extracellular signals controlling axonal growth are poorly understood. Here we report that a reduction in extracellular ATP levels by tissue-nonspecific alkaline phosphatase (TNAP) is essential for the development of neuritic processes by cultured hippocampal neurons. Selective blockade of TNAP activity with levamisole or specific TNAP knockdown with short hairpin RNA interference inhibited the growth and branching of principal axons, whereas addition of alkaline phosphatase (ALP) promoted axonal growth. Neither activation nor inhibition of adenosine receptors affected the axonal growth, excluding the contribution of extracellular adenosine as a potential hydrolysis product of extracellular ATP to the TNAP-mediated effects. TNAP was colocalized at axonal growth cones with ionotropic ATP receptors (P2X7 receptor), whose activation inhibited axonal growth. Additional analyses suggested a close functional interrelation of TNAP and P2X7 receptors whereby TNAP prevents P2X7 receptor activation by hydrolyzing ATP in the immediate environment of the receptor. Furthermore inhibition of P2X7 receptor reduced TNAP expression, whereas addition of ALP enhanced P2X7 receptor expression. Our results demonstrate that TNAP, regulating both ligand availability and protein expression of P2X7 receptor, is essential for axonal development
Economic analysis of the supercritical fluid extraction of lupane-triterpenoids from Acacia dealbata Link bark
The supercritical fluid extraction of Acacia dealbata Link. bark was performed with carbon dioxide at different pressures (10â30 MPa), temperatures (40â80 °C), and cosolvents contents (0â10 wt% of ethyl acetate or ethanol) to analyse their effect on various performance indicators whose best values were: total extraction yield of 1.57 wt%; lupenyl acetate (LA) and lupenone (Lu) extraction yields of 777.5 mg kgbark-1 and 679.8 mg kgbark-1; and LA and Lu extract concentrations of 15.8 wt% and 12.8 wt%. Two extraction curves were measured, and an economic analysis was accomplished. The impact of pressure, temperature, cosolvent content, and extraction time on the cost of manufacturing (COM) and productivity were evaluated, reaching a minimum of 52.3 ⏠kgextract-1. A sensitivity analysis showed that the electricity price is the most impactful variable on the COM. Overall, the increase of pressure, temperature and cosolvents content favoured the productivity, decreasing the production cost.publishe
Nesting behaviour influences species-specific gas exchange across avian eggshells
Carefully controlled gas exchange across the eggshell is essential for the development of the avian embryo. Water vapour conductance (GH2O) across the shell, typically measured as mass loss during incubation, has been demonstrated to optimally ensure the healthy development of the embryo while avoiding desiccation. Accordingly, eggs exposed to sub-optimal gas exchange have reduced hatching success. We tested the association between eggshell GH2O and putative life-history correlates of adult birds, ecological nest parameters and physical characteristics of the egg itself to investigate how variation in GH2O has evolved to maintain optimal water loss across a diverse set of nest environments. We measured gas exchange through eggshell fragments in 151 British breeding bird species and fitted phylogenetically controlled, general linear models to test the relationship between GH2O and potential predictor parameters of each species. Of our 17 life-history traits, only two were retained in the final model: wet-incubating parent and nest type. Eggs of species where the parent habitually returned to the nest with wet plumage had significantly higher GH2O than those of parents that returned to the nest with dry plumage. Eggs of species nesting in ground burrows, cliffs and arboreal cups had significantly higher GH2O than those of species nesting on the ground in open nests or cups, in tree cavities and in shallow arboreal nests. Phylogenetic signal (measured as Pagel's λ) was intermediate in magnitude, suggesting that differences observed in the GH2O are dependent upon a combination of shared ancestry and species-specific life history and ecological traits. Although these data are correlational by nature, they are consistent with the hypothesis that parents constrained to return to the nest with wet plumage will increase the humidity of the nest environment, and the eggs of these species have evolved a higher GH2O to overcome this constraint and still achieve optimal water loss during incubation. We also suggest that eggs laid in cup nests and burrows may require a higher GH2O to overcome the increased humidity as a result from the confined nest microclimate lacking air movements through the nest. Taken together, these comparative data imply that species-specific levels of gas exchange across avian eggshells are variable and evolve in response to ecological and physical variation resulting from parental and nesting behaviours
Quantum walk-based search algorithms with multiple marked vertices
The quantum walk is a powerful tool to develop quantum algorithms, which
usually are based on searching for a vertex in a graph with multiple marked
vertices, Ambainis's quantum algorithm for solving the element distinctness
problem being the most shining example. In this work, we address the problem of
calculating analytical expressions of the time complexity of finding a marked
vertex using quantum walk-based search algorithms with multiple marked vertices
on arbitrary graphs, extending previous analytical methods based on Szegedy's
quantum walk, which can be applied only to bipartite graphs. Two examples based
on the coined quantum walk on two-dimensional lattices and hypercubes show the
details of our method.Comment: 12 pages, 1 table, 2 fig
Simulation and techno-economic optimization of the supercritical CO2 extraction of Eucalyptus globulus bark at industrial scale
This work addresses economic and process aspects of the supercritical fluid extraction (SFE) of Eucalyptus globulus bark at industrial scale. Broken plus intact cells (BIC) model was applied to existing data and new SFE curves were simulated. Then, statistical optimization was performed with Response Surface Methodology (RSM) involving of 5 factors (pressure, temperature, cosolvent content, solvent flow rate and extraction time), and four responses: Total Yield (ηTotal), Productivity, Cost of Manufacturing (COM) and Process Energy. The design and simulation of the industrial process (Aspen PlusÂź software) was performed including the employment of cosolvent in the system. The best COM scored 28.1 ⏠kgextract-1, where ηTotal was 0.84-0.96 wt.%, Productivity reached 311â362 tonextractyear-1, and Process Energy scored 1.46â 2.10 GJ kgextract-1. These results underline that SFE provides an extended margin for trade-offs, and arguments towards the integration of SFE technology to biorefine the bark of E. globulus in pulp mills.publishe
Optimization of the supercritical fluid extraction of Quercus cerris cork towards extraction yield and selectivity to friedelin
Optimization of the supercritical fluid extraction of Quercus cerris cork was carried out using Box-Behnken design
of experiments and response surface methodology (RSM). The optimized process variables were temperature (T :
40, 50 and 60 °C), ethanol content (EtOH: 0.0, 2.5 and 5.0 wt%) and CO2 flow rate (QCO2: 5, 8 and 11 âg min )1 .
The studied responses were total extraction yield (ηTotal), friedelin concentration of the extract (CFriedelin), and
selectivity towards friedelin (αF,nF). The linear effect of EtOH was by far the most influent operating condition
(Pareto analysis) and the highest yield (ηTotal = 2.2 wt%) was attained with 5.0 wt% EtOH. The RSM model
estimates maximum friedelin concentration in the extracts (38.2 wt%) to occur without cosolvent (0 wt% EtOH)
for the lowest T (40 °C) and QCO2 (5 âg min )CO2
1 . As for selectivity, the experimental αF,nF values were always
higher than 1.0 and reached 3.1 (at 50 °C, 5 wt% EtOH, 11 âg minCO2
1). Altogether, these results suggest
friedelin can be selectively removed from Quercus cerris cork by supercritical fluid extraction within the range of
experimental conditions studiedpublishe
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