Site recurrence of open and unitary quantum walks on the line

We study the problem of site recurrence of discrete-time nearest-neighbor open quantum random walks (OQWs) on the integer line, proving basic properties and some of its relations with the corresponding problem for unitary (coined) quantum walks (UQWs). For both kinds of walks, our discussion concerns two notions of recurrence, one given by a monitoring procedure (Grünbaum et al. in Commun Math Phys 320:543–569, 2013; Lardizabal and Souza in J Stat Phys 159:772–796, 2015), and we study their similarities and differences. In particular, by considering UQWs and OQWs induced by the same pair of matrices, we discuss the fact that recurrence of these walks is related by an additive interference term in a simple way. Based on a previous result of positive recurrence, we describe an open quantum version of Kac’s lemma for the expected return time to a site.     

Thermal degradation kinetics of anthocyanins and visual colour of Urmu mulberry (Morus nigra L.)

Urmu mulberry (Morus nigra L.) juice was concentrated from 15.02 to 45.20 °Brix by rotary vacuum evaporator at 40 °C. The objectives of this study were to determine the titratable acidity, soluble solid content, antioxidant capacity, total monomeric anthocyanins and total phenolic matter in prepared concentrate, to investigate the thermal degradation kinetics of anthocyanins and Hunter colour parameters (L^∗, a^∗, b^∗) and total colour difference (TCD^∗) and to develop a relationship between visual colour and anthocyanin during thermal processing at 60, 70 and 80 °C. Monomeric anthocyanin degradation showed a first order reaction kinetics. The zero order, first order and a combined kinetics model were applied to the changes in Hunter colour parameters (L^∗, a^∗ and b^∗) and total colour difference (TCD^∗). All colour parameters followed an apparent combined kinetics model. The degradation of anthocyanins showed positive correlation with a^∗, b^∗ and L^∗ and negative correlation with TCD^∗.     

Coordination of multiple appendages in drag-based swimming

Krill are aquatic crustaceans that engage in long distance migrations, either vertically in the water column or horizontally for 10 km (over 200 000 body lengths) per day. Hence efficient locomotory performance is crucial for their survival. We study the swimming kinematics of krill using a combination of experiment and analysis. We quantify the propulsor kinematics for tethered and freely swimming krill in experiments, and find kinematics that are very nearly metachronal. We then formulate a drag coefficient model which compares metachronal, synchronous and intermediate motions for a freely swimming body with two legs. With fixed leg velocity amplitude, metachronal kinematics give the highest average body speed for both linear and quadratic drag laws. The same result holds for five legs with the quadratic drag law. When metachronal kinematics is perturbed towards synchronous kinematics, an analysis shows that the velocity increase on the power stroke is outweighed by the velocity decrease on the recovery stroke. With fixed time-averaged work done by the legs, metachronal kinematics again gives the highest average body speed, although the advantage over synchronous kinematics is reduced.     

Selenium depuration: residual effects of dietary selenium on Sacramento splittail (Pogonichthys macrolepidotus)

We examined the growth performance, tissue selenium (Se) concentration, and histopathology of Sacramento splittail (Pogonichthys macrolepidotus) fed a control diet (0.4 microg Se/g) for 1, 3, 7, 13, 21 wk after a 9-month dietary exposure to 0.4, 12.6, 26.0, and 57.6 microg Se/g dry diet. Splittail previously fed 57.6 microg Se/g showed a significantly (P<0.05) lower final body weight but had higher weight gain than fish fed 0.4 microg Se/g diet at the end of the 21-wk depuration study. There were no significant differences in body weight in fish previously fed diets with or less than 26.0 microg Se/g. Liver and muscle Se concentrations decreased significantly in fish previously fed 26.0 and 57.6 microg Se/g diet but did not change significantly in fish fed 12.6 or less mug Se/g diet at the end of 21 wk. Liver Se concentrations dropped to the same concentration as fish fed 0.4 microg Se/g diet after a 13-wk depuration in all treatments. Muscle Se concentrations remained significantly higher in fish previously fed 12.6 or higher microg Se/g diets when compared to fish fed control diet at the end of a 21-wk depuration. Except for the presence of preneoplastic basophilic foci in two fish previously fed 57.6 microg Se/g diet, normal liver morphology was observed in splittail in all treatments at the end of 21-wk depuration. Prevalences of kidney lesions were increased in fish previously fed 26.0 and 57.6 microg Se/g diets at 3 and 7 wk, and decreased at 13 and 21 wk of depuration. No kidney lesions were observed in fish previously fed 12.6 microg Se/g diet or less. In conclusion, growth of splittail previously fed a diet containing 57.6 microg Se/g was still affected at the end of 21-wk depuration. The 21-wk depuration was not long enough for muscle Se concentrations to return to basal levels in fish previously fed 12.6 or more microg Se/g diet. Deleterious health effects of Se persisted in fish previously fed diets with 26.0 or more microg Se/g diet. Current results suggest that splittail that survived the 9-month exposure to 12.6 or less microg Se/g diet under current laboratory conditions is likely to thrive if Se in diet was reduced to control concentration.     

Policy factors explaining the failure of delegated management in water supply: evidence from Ghana

In the 1990s, delegated management emerged as a promising public policy approach for improving the performance of the water supply sector in many developing countries. In many cases, however, the obligations of delegated management contracts reportedly have not been met, often leading to early termination or non-renewal. Drawing on theories in policy analysis and knowledge management, this article analyzes the management contract signed between Ghana Water Company and Aqua Vitens Rand to identify the policy-related factors underlying the failure of delegated management in water supply. Practical implications are discussed for more successful implementation of delegated management.     

Species-Specific Chemical Signatures in Scale Insect Honeydew

The quantity and chemical composition of honeydew produced by scale insects may influence wider community structure, but little is known about the detailed chemical composition of the honeydew found in forest ecosystems. We used gas chromatography-mass spectrometry to examine the amino acid and carbohydrate composition of honeydew from three New Zealand communities. Low molecular weight carbohydrates (mono-, di-, and tri-saccharides) were derivatized using a modified trimethylsilyl (TMS) method, and amino and non-amino organic acids were derivatized using methylchloroformate (MCF). These recently developed derivatization methods allowed us to detect atypical compounds such as sugar alcohols, fatty acids, and non-amino organic acids, in addition to the more routinely studied compounds such as sugars and amino acids. Some compounds could not be identified and may be novel. Multivariate analysis showed that honeydew from each scale insect species had a distinctive amino acid and carbohydrate signature. We suggest these chemical signatures may influence the types of consumers that are attracted to different honeydews and may explain the characteristic communities associated with these honeydews.     

Regeneration/Optimization of Activated Carbon Monolith in Simultaneous SO2/NOx Removal from Flue Gas

Due to the adverse effects of SO₂/NO_x on humans and the environment, environmental regulations necessitate the control of their emission. In this study, an activated carbon monolith was synthesized with cobalt oxide (ACM‐Co₃O₄) for the purpose of simultaneous SO₂/NO_x removal from flue gas generated by coal combustion. Average regeneration efficiencies of 92.7 and 94.2 % were obtained for SO₂ and NO_x, respectively. The Langmuir model can adequately describe the experimental results of the ACM‐Co₃O₄ adsorbent in SO₂ and NO_x removal. The key regeneration parameters were optimized by using the response surface methodology (RSM). The RSM results revealed that the statistical prediction and experimental results were in agreement.     

Investigation on the charging process of Li2O2-based air electrodes in Li-O2 batteries with organic carbonate electrolytes

The charging process of Li₂O₂-based air electrodes in Li-O₂ batteries with organic carbonate electrolytes was investigated using in situ gas chromatography/mass spectroscopy (GC/MS) to analyze gas evolution. A mixture of Li₂O₂/Fe₃O₄/Super P carbon/polyvinylidene fluoride (PVDF) was used as the starting air electrode material, and 1-M lithium bis(trifluoromethylsulfonyl)imide (LiTFSI) in carbonate-based solvents was used as the electrolyte. We found that Li₂O₂ was actively reactive to 1-methyl-2-pyrrolidinone and PVDF that were used to prepare the electrode. During the first charging (up to 4.6 V), O₂ was the main component in the gases released. The amount of O₂ measured by GC/MS was consistent with the amount of Li₂O₂ that decomposed during the electrochemical process as measured by the charge capacity, which is indicative of the good chargeability of Li₂O₂. However, after the cell was discharged to 2.0 V in an O₂ atmosphere and then recharged to ∼4.6 V, CO₂ was dominant in the released gases. Further analysis of the discharged air electrodes by X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy indicated that lithium-containing carbonate species (lithium alkyl carbonates and/or Li₂CO₃) were the main discharge products. Therefore, compatible electrolytes and electrodes, as well as the electrode-preparation procedures, need to be developed for rechargeable Li-air batteries for long term operation.