Real-valued algebro-geometric solutions of the Camassa-Holm hierarchy

We provide a detailed treatment of real-valued, smooth and bounded algebro-geometric solutions of the Camassa-Holm (CH) hierarchy and describe the associated isospectral torus. We employ Dubrovin-type equations for auxiliary divisors and certain aspects of direct and inverse spectral theory for self-adjoint Hamiltonian systems. In particular, we rely on Weyl-Titchmarsh theory for singular (canonical) Hamiltonian systems. We also briefly discuss real-valued algebro-geometric solutions with a cusp behaviour. While we focus primarily on the case of stationary algebro-geometric CH solutions, we note that the time-dependent case subordinates to the stationary one with respect to isospectral torus questions.     

Exposure to virtual nature: the impact of different immersion levels on skin conductance level,heart rate,and perceived relaxation

Virtual Reality - It is generally accepted that natural environments reduce stress and improve mood. Since access to natural environments is sometimes limited, virtual natural environments,...     

Response of a proton exchange membrane fuel cell to a sinusoidal current load

The load-following capability of a proton exchange membrane fuel cell was studied by measuring the cell voltage response to a sinusoidal current load with large amplitude and varying frequency. A mathematical model was developed, incorporating mass transport and capacitive effects as well as the membrane resistance. The model was capable of separating the faradaic and capacitive currents and predicting the observed hysteresis. At frequencies of the sinusoidal current load below 1 Hz, no appreciable hysteresis in the polarisation curve was observed. When increasing the frequency above 1 Hz, a hysteresis appeared at current densities below 0.2 A cm^?2. The model related this hysteresis to capacitive effects. When using air as the cathode feed, hysteresis in the current density range 0.5 A cm^?2 and higher appeared above 1 Hz compared to 100 Hz for pure oxygen. The model revealed that hysteresis observed in this current density range was caused by oxygen transport limitations.     

Defect studies on as-synthesized and purified carbon nanostructures produced by arc-discharge in solution process

Carbon nanostructures are synthesized using a novel arc-discharge in solution process. A multitude of defects on nanotubes and nanostructures is found. Evidence of these defects in as-synthesized carbon nanostructures is explored using high-resolution transmission electron microscopy (HRTEM). Tri-, tetra-, penta-, hexa-, heptagonal, toroidal, oval, and spherical nanoshells are found in HRTEM investigation along with carbon nanotubes, carbon nanohorns, carbon rods, nanoporous carbon, dislodged graphene sheets, and amorphous carbon. Purifications are carried out through two oxidation methods to eliminate the amorphous carbon. Several different defects caused by oxidations are also found in purified samples.     

Neutral loss fragmentation pattern based screening for arginine-rich natural products in xenorhabdus and photorhabdus

Although sharing a certain degree of structural uniformity, natural product classes exhibit variable functionalities such as different amino acid or acyl residues. During collision induced dissociation, some natural products exhibit a conserved fragmentation pattern close to the precursor ion. The observed fragments result from a shared set of neutral losses, creating a unique fragmentation pattern, which can be used as a fingerprint for members of these natural product classes. The culture supernatants of 69 strains of the entomopathogenic bacteria Photorhabdus and Xenorhabdus were analyzed by MALDI-MS(2), and a database comprising MS(2) data from each strain was established. This database was scanned for concordant fragmentation patterns of different compounds using a customized software, focusing on relative mass differences of the fragment ions to their precursor ion. A novel group of related natural products comprising 25 different arginine-rich peptides from 16 different strains was identified due to its characteristic neutral loss fragmentation pattern, and the structures of eight compounds were elucidated. Two biosynthesis gene clusters encoding nonribosomal peptide synthetases were identified, emphasizing the possibility to identify a group of structurally and biosynthetically related natural products based on their neutral loss fragmentation pattern.     

Effect of gas composition and gas utilisation on the dynamic response of a proton exchange membrane fuel cell

The transient response of a proton exchange membrane fuel cell (PEMFC) was measured for various cathode gas compositions and gas utilisations (fraction of supplied reactant gas which is consumed in the fuel cell reaction). For a PEMFC operated on pure hydrogen and oxygen, the cell voltage response to current steps was fast, with response times in the range 0.01–1 s, depending on the applied current. For a PEMFC supplied with air as cathode gas, an additional relaxation process related to oxygen transport caused a slower response (approximately 0.1–2 s depending on the applied current). Response curves up to approximately 0.01 s were apparently unaffected by gas composition and utilisation and were most likely dominated by capacitive discharge of the double layer and reaction with surplus oxygen residing in the cathode. The utilisation of hydrogen had only a minor effect on the response curves, while the utilisation of air severely influenced the PEMFC dynamics. Results suggested that air flow rates should be high to obtain rapid PEMFC response.     

Building in economic terms

The housing achievements of the Nordic countries in the past two decades are internationally recognised. Here, a distinguished Norwegian economist and former Minister argues that future policies must be based on the optimum use of resources, and one of the greatest real resources is the existing housing stock.     

Multicriteria dimensioning of hard-finishing operations regarding cross-process interdependencies

The production of high performance metal parts requires a well balanced sequence of operations and can usually technologically not be achieved in a single process. This issue leads to complex process chains on the shop floor and the requirement to split single processes into multistage processes in hard-finishing operations. In both cases, the objective for the process planning is to achieve not only a local optimum for the individual processes but rather an overall optimum for the complete sequence. In order to reach the overall optimum, the process planner needs to integrate the effects between the processes into consideration. These effects which are referred to as cross-process interdependencies lead to balanced settings of process parameters and results in a much more effective operation of the sequence. In this paper, a novel approach dealing with the integration of cross-process interdependencies in the hard-finishing process of multistage grinding is introduced. It is based on an a-priori multicriteria dimensioning procedure which allows the integration of cross-process interdependencies and is implemented in software programmed in JAVA. A multistage plunge grinding process for crankshaft journals is used for evaluation of the results predicted by a developed software prototype.