Lagrangian and Hamiltonian two-scale reduction

Studying high-dimensional Hamiltonian systems with microstructure, it is an important and challenging problem to identify reduced macroscopic models that describe some effective dynamics on large spatial and temporal scales. This paper concerns the question how reasonable macroscopic Lagrangian and Hamiltonian structures can by derived from the microscopic system. In the first part we develop a general approach to this problem by considering non-canonical Hamiltonian structures on the tangent bundle. This approach can be applied to all Hamiltonian lattices (or Hamiltonian PDEs) and involves three building blocks: (i) the embedding of the microscopic system, (ii) an invertible two-scale transformation that encodes the underlying scaling of space and time, (iii) an elementary model reduction that is based on a Principle of Consistent Expansions. In the second part we exemplify the reduction approach and derive various reduced PDE models for the atomic chain. The reduced equations are either related to long wave-length motion or describe the macroscopic modulation of an oscillatory microstructure.Comment: 40 page

Comparison of two perennial energy crops for biomass production at the end of their life cycle

Nowadays fossil fuels are decreasing, causing the world's interest in renewable energy sources to rapidly grow. One of the most interesting renewable and ecologically pure fuels is biomass, which is considered to be carbon neutral. Biomass is a promising source of energy, as it can be used directly as an energy resource. Its quality characteristics such as gross calorific value and ash content are of paramount importance so as to improve the combustion process. Furthermore, during the last three decades, there has been an increasing interest in the production of biomass pellets for domestic and industrial use. Alternative feed stocks will need to be sourced to meet the demand for biomass pellets. Investigation for new energy crops that produce high amounts of biomass under low inputs and of high energy efficiency are the main tasks of this field. Therefore, the aim of this study is to assess the biomass yield and the quality characteristics (gross calorific value and ash content) of two perennial energy crops (Cynara cardunculus L. and Panicum virgatum L.) growing in a typical soil (Fluventic Xerochrept) of the main agricultural land of central Greece. The comparison for both cultivated crops was made in order to show the results during their 8th growing year. The examined factors were the irrigation (two levels: irrigated and rainfed) and the nitrogen fertilization (two levels: 0 and 80 kg N ha-1 ) as well as their effect on the dry biomass yield and the gross calorific value. It was found that higher dry biomass yield was produced from cardoon (21.3 vs. 14.23 t ha-1 ), while the higher average gross calorific value was observed for switchgrass biomass (17.31 vs. 15.65 Mj kg-1 ). Finally, multiplying the dry biomass yield (t ha-1 ) with the gross calorific value (Mj kg-1 ) it was found that 334 and 245 Gj ha-1 from a cardoon and a switchgrass cultivation could be produced, respectively. Cardoon has better results than switchgrass probably due to the fact that switchgrass is growing from March till October; while cardoon’s growing period is from October to June and in such areas precipitation is in shortage during summer months. Both crops could achieve high amounts of energy per hectare and thus their introduction in future land use systems, for an environmentally friendly energy production should be seriously taken into consideration

Sorghum dry biomass yield for solid bio-fuel production affected by different N-fertilization rates

The objective of this study was to examine the effect on the dry biomass yield of two dfferent sorghum hybrids (H1 and H2) under five different N-fertilization levels (0, 70, 140, 210 and 280 kg ha-1 ) in a soil which was formed by lacustrine deposits of Karla Lake and is characterized from the downward movement of calcium carbonate from the surface horizons due to leaching (Fluventic Xerochrept) during 2017. The results demonstrated a significant effect (P < 0.05) of fertilization only for one hybrid. Biomass yield ranged from 22.2 to 37.5 t ha−1. For both hybrids, sorghum accumulated a high amount of biomass in stems. Dry stem/total biomass ratio was rather constant throughout the different fertilization treatments achieving 81.6 and 77.5% for the first (H1) and the second hybrid (H2), respectively. The second hybrid (H2) had a higher percentage of leaf biomass (20.1 vs. 13.8%) than the first (H1), but lagged behind in seed production (2.4 vs. 4.6%). Biomass dry matter partitioning and total dry weight are important selection criteria for energy crops, due to different gross calorific value and ash content but also because of the different economic importance they may have e.g. the seed is also used as animal feed. The above high biomass yields of sorghum, confirming the high potential of this crop, should be taken into serious consideration regarding land use planning, but further investigation for the gross calorific value and the ash content is needed as well as biomass characteristics that are quite important in case to improve the combustion process

Bifurcations of discrete breathers in a diatomic Fermi-Pasta-Ulam chain

Discrete breathers are time-periodic, spatially localized solutions of the equations of motion for a system of classical degrees of freedom interacting on a lattice. Such solutions are investigated for a diatomic Fermi-Pasta-Ulam chain, i. e., a chain of alternate heavy and light masses coupled by anharmonic forces. For hard interaction potentials, discrete breathers in this model are known to exist either as ``optic breathers'' with frequencies above the optic band, or as ``acoustic breathers'' with frequencies in the gap between the acoustic and the optic band. In this paper, bifurcations between different types of discrete breathers are found numerically, with the mass ratio m and the breather frequency omega as bifurcation parameters. We identify a period tripling bifurcation around optic breathers, which leads to new breather solutions with frequencies in the gap, and a second local bifurcation around acoustic breathers. These results provide new breather solutions of the FPU system which interpolate between the classical acoustic and optic modes. The two bifurcation lines originate from a particular ``corner'' in parameter space (omega,m). As parameters lie near this corner, we prove by means of a center manifold reduction that small amplitude solutions can be described by a four-dimensional reversible map. This allows us to derive formally a continuum limit differential equation which characterizes at leading order the numerically observed bifurcations.Comment: 30 pages, 10 figure

Popliteal artery damage during total knee arthroplasty

AbstractInjury of popliteal artery during total knee arthroplasty is a relatively rare complication. We report on one case of transverse semi-dissection of the popliteal artery during the tibial cut and one case of popliteal pseudoaneurysm formation caused by Hohmann retractors. Diagnosis was made early in the first case but it was delayed in the second due to misdiagnosis of deep vein thrombosis. Both injuries were managed eventually by open surgery. Postoperative clinical examination and ultrasound imaging confirmed the successful restoration of the blood flow. This case report also describes the classification system of the type of vascular damage and describes the mechanism, the clinical presentation, diagnostic modalities and treatment options for these rare complications of total knee arthroplasty surgery

O-band QKD link over a multiple ONT loaded carrier-grade GPON for FTTH applications

We have successfully integrated an O-band commercial Quantum-Key-Distribution (QKD) system over a lit GPON testbed that replicates a carrier-grade Fiber-to-the-Home (FTTH) optical access network with multiple ONTs to emulate real-life FTTH operational deployments.Comment: 3 page

Sub-micromolar pulse dipolar EPR spectroscopy reveals increasing CuII-labelling of double-histidine motifs with lower temperature

Electron paramagnetic resonance (EPR) distance measurements are making increasingly important contributions to the studies of biomolecules by providing highly accurate geometric constraints. Combining double-histidine motifs with CuII spin labels can further increase the precision of distance measurements. It is also useful for proteins containing essential cysteines that can interfere with thiol-specific labelling. However, the non-covalent CuII coordination approach is vulnerable to low binding-affinity. Herein, dissociation constants (KD) are investigated directly from the modulation depths of relaxation-induced dipolar modulation enhancement (RIDME) EPR experiments. This reveals low- to sub-μm CuII KDs under EPR distance measurement conditions at cryogenic temperatures. We show the feasibility of exploiting the double-histidine motif for EPR applications even at sub-μm protein concentrations in orthogonally labelled CuII–nitroxide systems using a commercial Q-band EPR instrument.Publisher PDFPeer reviewe

The effect of citicoline oral solution on quality of life in patients with glaucoma: the results of an international, multicenter, randomized, placebo-controlled cross-over trial

PURPOSE: This study aims to evaluate whether the use of citicoline oral solution could improve quality of life in patients with chronic open-angle glaucoma (OAG). DESIGN: Randomized, double-masked, placebo-controlled, cross-over study was used. Patients were randomized to one of the two sequences: either citicoline 500 mg/day oral solution-placebo or placebo-citicoline 500 mg/day oral solution. Switch of treatments was done after 3 months; patients were then followed for other 6 months. Follow-up included 3-month, 6-month, and 9-month visits. OUTCOMES: The primary outcome was the mean change of "intra-patient" composite score of the Visual Function Questionnaire-25 (VFQ-25). after citicoline oral solution vs placebo at 6-month visit as compared with baseline. METHODS: The trial was multicenter, conducted at 5 European Eye Clinics. OAG patients with bilateral visual field damage, a mean deviation (MD) ranging from - 5 to - 13 dB in the better eye, and controlled IOP were included. VFQ-25 and SF-36 questionnaires were administered at baseline and at 3-, 6-, and 9-month visits. A mixed effect model, with a random effect on the intercept, accounted for correlations among serial measurements on each subject. RESULTS: The primary pre-specified outcome of the analysis reached statistical significance (p = 0.0413), showing greater improvement after citicoline oral solution. There was an increase in the composite score in both arms compared to baseline, but it was significant only for the placebo-citicoline arm (p = 0.0096, p = 0.0007, and p = 0.0006 for the three time-points compared to baseline). The effect of citicoline was stronger in patients with vision-related quality of life more affected by glaucoma at baseline. CONCLUSIONS: This is the first placebo-controlled clinical study evaluating the effect of a medical treatment aiming at improving vision-related quality of life in glaucomatous patients