Compression-based fixed-parameter algorithms for feedback vertex set and edge bipartization

We show that the NP-complete Feedback Vertex Set problem, which asks for the smallest set of vertices to remove from a graph to destroy all cycles, is deterministically solvable in O(ck⋅m) time. Here, m denotes the number of graph edges, k denotes the size of the feedback vertex set searched for, and c is a constant. We extend this to an algorithm enumerating all solutions in O(dk⋅m) time for a (larger) constant d. As a further result, we present a fixed-parameter algorithm with runtime O(k²⋅m²) for the NP-complete Edge Bipartization problem, which asks for at most k edges to remove from a graph to make it bipartite.     

Density-based retrieval from high-similarity image databases

Many image classification problems can fruitfully be thought of as image retrieval in a “high similarity image database” (HSID) characterized by being tuned towards a specific application and having a high degree of visual similarity between entries that should be distinguished. We introduce a method for HSID retrieval using a similarity measure based on a linear combination of Jeffreys-Matusita distances between distributions of local (pixelwise) features estimated from a set of automatically and consistently defined image regions. The weight coefficients are estimated based on optimal retrieval performance. Experimental results on the difficult task of visually identifying clones of fungal colonies grown in a petri dish and categorization of pelts show a high retrieval accuracy of the method when combined with standardized sample preparation and image acquisition.     

Isogeometric shape optimization of vibrating membranes

We consider a model problem of isogeometric shape optimization of vibrating membranes whose shapes are allowed to vary freely. The main obstacle we face is the need for robust and inexpensive extension of a B-spline parametrization from the boundary of a domain onto its interior, a task which has to be performed in every optimization iteration. We experiment with two numerical methods (one is based on the idea of constructing a quasi-conformal mapping, whereas the other is based on a spring-based mesh model) for carrying out this task, which turn out to work sufficiently well in the present situation. We perform a number of numerical experiments with our isogeometric shape optimization algorithm and present smooth, optimized membrane shapes. Our conclusion is that isogeometric analysis fits well with shape optimization.     

Lattice Boltzmann simulations in microfluidics: probing the no-slip boundary condition in hydrophobic, rough, and surface nanobubble laden microchannels

In this contribution, we review recent efforts on investigations of the effect of (apparent) boundary slip by utilizing lattice Boltzmann simulations. We demonstrate the applicability of the method to treat fundamental questions in microfluidics by investigating fluid flow in hydrophobic and rough microchannels as well as over surfaces covered by nano- or microscale gas bubbles.     

Defining and controlling the heterogeneity of a cluster: The Wrekavoc tool

The experimental validation and the testing of solutions that are designed for heterogeneous environments are challenging. We introduce Wrekavoc as an accurate tool for this purpose: it runs unmodified applications on emulated multi-site heterogeneous platforms. Its principal technique consists in downgrading the performance of the platform characteristics in a prescribed way. The platform characteristics include the compute nodes themselves (CPU and memory) and the interconnection network for which a controlled overlay network above the homogeneous cluster is built. In this article we describe the tool, its performance, its accuracy and its scalability. Results show that Wrekavoc is a very versatile tool that is useful to perform high-quality experiments (in terms of reproducibility, realism, control, etc.).     

Model-based cloud resource management with TOSCA and OCCI

Software and Systems Modeling - With the advent of cloud computing, different cloud providers with heterogeneous cloud services (compute, storage, network, applications, etc.) and their related...     

Das Fachinformationssystem Hydrogeologie im Umweltinformationssystem Sachsen – Stand und praktische Anwendung

The branch information system “Hydrogeology” is part of the environmental information system of the federal state Saxony/Germany. The system comprises the decentral and the central data collection, central data storage and management as well as methods for data processing. As yet, data stocks and software were implemented particularly for point related data including applications for data collection, for the interpretation of pumping tests and grain size analysis as well as visualization. Maps are based on the implemented software applications and database structures. These data are an essential help in decisive processes for administrative objectives with a hydrogeologial and environmental background. Databases and methods for area-related data have been built up and already used for generation of maps.     

Preparing for novel versus familiar events: Shifts in global and local processing.

Six experiments examined whether novelty versus familiarity influences global versus local processing styles. Novelty and familiarity were manipulated by either framing a task as new versus familiar or by asking participants to reflect upon novel versus familiar events prior to the task (i.e., procedural priming). In Experiments 1–3, global perception was enhanced after novelty priming or framing, whereas familiarity priming facilitated local perception relative to a control group. In Experiment 4, participants used more inclusive categories under novelty priming and narrower categories under familiarity priming. In Experiments 5–6, participants construed actions and products more abstractly when these were framed as novel as compared to familiar. These results support the construal level theory (N. Liberman & Y. Trope, 2008; Y. Trope & N. Liberman, 2003) contention that having less direct experience is associated with using higher construal levels. Implications of the findings for research on mood, processing styles, stereotypes, and consumer research are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cutting stress off at the pass: Reducing vigilance and responsiveness to social threat by manipulating attention.

Personality processes relating to social perception have been shown to play a significant role in the experience of stress. In 5 studies, the authors demonstrate that early stage attentional processes influence the perception of social threat and modify the human stress response. The authors first show that cortisol release in response to a stressful situation correlates with selective attention toward social threat. Second, the authors show in 2 laboratory studies that this attentional pattern, most evident among individuals with low self-esteem, can be modified with a repetitive training task. Next, in a field study, students trained to modify their attentional pattern to reduce vigilance for social threat showed lower self-reported stress related to their final exam. In a final field study with telemarketers, the attentional training task led to increased self-esteem, decreased cortisol and perceived stress responses, higher confidence, and greater work performance. Taken together, these results demonstrate the impact of antecedent-focused strategies on the late-stage consequences of social stress. (PsycINFO Database Record (c) 2010 APA, all rights reserved)