Nonexistence results for the Korteweg-deVries and Kadomtsev-Petviashvili equations

We study characteristic Cauchy problems for the Korteweg-deVries (KdV) equation $u_t=uu_x+u_{xxx}$, and the Kadomtsev-Petviashvili (KP) equation $u_{yy}=\bigl(u_{xxx}+uu_x+u_t\bigr)_x$ with holomorphic initial data possessing nonnegative Taylor coefficients around the origin. For the KdV equation with initial value $u(0,x)=u_0(x)$, we show that there is no solution holomorphic in any neighbourhood of $(t,x)=(0,0)$ in ${\mathbb C}^2$ unless $u_0(x)=a_0+a_1x$. This also furnishes a nonexistence result for a class of $y$-independent solutions of the KP equation. We extend this to $y$-dependent cases by considering initial values given at $y=0$, $u(t,x,0)=u_0(x,t)$, $u_y(t,x,0)=u_1(x,t)$, where the Taylor coefficients of $u_0$ and $u_1$ around $t=0$, $x=0$ are assumed nonnegative. We prove that there is no holomorphic solution around the origin in ${\mathbb C}^3$ unless $u_0$ and $u_1$ are polynomials of degree 2 or lower.Comment: 17 pages in LaTeX2e, to appear in Stud. Appl. Mat

construct dikes or erect windmills? A synthesis of cultural theory and new institutional economics perspectives

Climate change affects the entire globe. However, its effects are influenced by differing geographic expositions and unevenly spread social adaptation capacities. Empirically, different levels of social vulnerability can be observed which are explained by distinct levels of wealth – so the general explanation goes. Such correlations cannot be neglected and are quite trivial: assuming similar expositions, The Netherlands are better prepared to construct dikes against flooding than Bangladesh. But what is about different vulnerabilities occurring despite of comparable levels of wealth? Why is it that the Mississippi delta was devastated by hurricane Katrina whereas the Rhine-Meuse delta remained almost unaffected up to now? What accounts for the fact that Texas, not really know for caring much for environmental niceties, has set up more windmills than California and is close to outpace Denmark and Germany with respect to the production of wind power? How can it be that Texas nevertheless rejects any environmental political guidelines from Washington? These questions are discussed by amalgamating the Cultural Theory (Douglas/Wildavsky 1982, Schwarz/Thompson 1990) and the Varieties of Capitalism approach (Hall/Soskice 2001). The rationality behind this idea is that societies which are rather coined by collective and egalitarian principles are better prepared to cope with cooperative tasks like building dikes whereas individualistic institutions and convictions result in a situation in which the rich seek shelter whereas the poor are left alone. Contrary, it is easier to realize (environmental-)innovations like windmills within a liberal context. That is because it is easier to raise venture capital and to overcome opposition within the neighbourhood (among other things). Our theoretical argument picks up the vaguely claimed correlation of cultural frames of interpretation and socio-economic institutions (Dryzek 2008, Mamadouh 1999) and explores it in greater depth

Use Cases and Collaboration Scenarios: how employees use socially-enabled Enterprise Collaboration Systems (ECS)

In recent years we have seen the emergence of a new type of collaboration software, the so-called “Enterprise Social Software”. The “social features” of this software type have stimulated a renewed interest in Enterprise Collaboration Systems (ECS). In this article we present findings from a longitudinal research project on the introduction and use of ECS in companies. We argue that ERP Systems and ECS are inherently different and that the process-paradigm that is common to ERP cannot be applied identically to ECS. To address this issue, we suggest the two concepts use case and collaboration scenario for the analysis and description of collaboration activity in companies. From the literature and 26 case studies we identified typical use cases and collaboration scenarios that can serve as blueprints for ECS introduction projects. The longitudinal objective of our research is to assist companies with their ECS initiatives and to provide them with a catalog of existing use cases and collaboration scenarios from various industry settings

Airway responses and inflammation in subjects with asthma after four days of repeated high-single-dose allergen challenge

Background: Both standard and low-dose allergen provocations are an established tool in asthma research to improve our understanding of the pathophysiological mechanism of allergic asthma. However, clinical symptoms are less likely to be induced. Therefore, we designed a protocol for repetitive high-dose bronchial allergen challenges to generate clinical symptoms and airway inflammation. Methods: A total of 27 patients aged 18 to 40 years with positive skin-prick tests and mild asthma underwent repetitive high-dose allergen challenges with household dust mites for four consecutive days. Pulmonary function and exhaled NO were measured at every visit. Induced sputum was analysed before and after the allergen challenges for cell counts, ECP, IL-5, INF-γ, IL-8, and the transcription factor Foxp3. Results: We found a significant decrease in pulmonary function, an increased use of salbutamol and the development of a late asthmatic response and bronchial hyperresponsiveness, as well as a significant induction of eNO, eosinophils, and Th-2 cytokines. Repeated provocation was feasible in the majority of patients. Two subjects had severe adverse events requiring prednisolone to cope with nocturnal asthma symptoms. Conclusions: Repeated high-dose bronchial allergen challenges resulted in severe asthma symptoms and marked Th-2-mediated allergic airway inflammation. The high-dose challenge model is suitable only in an attenuated form in diseased volunteers for proof-of-concept studies and in clinical settings to reduce the risk of severe asthma exacerbations. Trial registration: ClinicalTrials.govNCT0067720

Magnus and Dyson Series for Master Integrals

We elaborate on the method of differential equations for evaluating Feynman integrals. We focus on systems of equations for master integrals having a linear dependence on the dimensional parameter. For these systems we identify the criteria to bring them in a canonical form, recently identified by Henn, where the dependence of the dimensional parameter is disentangled from the kinematics. The determination of the transformation and the computation of the solution are obtained by using Magnus and Dyson series expansion. We apply the method to planar and non-planar two-loop QED vertex diagrams for massive fermions, and to non-planar two-loop integrals contributing to 2 -> 2 scattering of massless particles. The extension to systems which are polynomial in the dimensional parameter is discussed as well.Comment: 32 pages, 6 figures, 2 ancillary files. v2: references added, typos corrected in the text and in the ancillary file

Molecular wires:impact of π-conjugation and implementation of molecular bottlenecks

In this review we highlight recent progress in the field of photochemically and thermally induced electron transport through molecular bridges as integrative parts of electron donor–bridge–acceptor conjugates. The major emphasis is hereby on the design and the modular composition of the bridges. To this end, we will demonstrate that control over attenuation factors and reorganization energies, on one hand, as well as electronic and electron–vibration couplings, on the other hand, enables tuning electron transport over distances as short as 3.5 Å and as large as 50 Å by up to nine orders of magnitude. In terms of electron transport, the maximum extreme is given by carbon-bridged oligo-p-phenylenevinylenes of different lengths, while a zinc tetraphenylporphyrin free base tetraphenylporphyrin dyad constitutes the minimum extreme

Advances in application of the limiting current technique for solid-liquid mass transfer investigations

The limiting current technique has widely been used to study liquid-solid mass transfer in various reactor configurations. In the present contribution several underlying physical aspects have been investigated in order to improve the design of mass transfer experiments. Experimentally, the significant influence of electrolyte composition and hydrodynamic conditions have been studied and quantified to ensure conditions of high reproducibility. In the course of single phase COMSOL simulations, different electrode configurations have been examined with emphasis on concentration fields and electric current distribution showing a large sensitivity of the experimental configuration on the absolute current values

Exploring the Applicability of Sinterjoining to Combine Additively Manufactured Ceramic Components

This paper examines the general applicability of sinterjoining for combining the advantages of Ceramic Injection Molding (CIM) and Additive Manufacturing (AM) as well as different AM processes. To do so, the geometric tolerance, the pre-sintering temperature and the co-sintering time are varied exemplarily on samples produced by vat photopolymerization (VPP) to minimize the force required for inserting the bodies and to maximize the degree of sintering. The results show that degrees of sintering larger 90 % can be obtained reproducibly. Thus, sinterjoining can be considered as a promising approach for combining the advantages of several ceramic manufacturing processes