Particle number conservation in quantum many-body simulations with matrix product operators

Incorporating conservation laws explicitly into matrix product states (MPS) has proven to make numerical simulations of quantum many-body systems much less resources consuming. We will discuss here, to what extent this concept can be used in simulation where the dynamically evolving entities are matrix product operators (MPO). Quite counter-intuitively the expectation of gaining in speed by sacrificing information about all but a single symmetry sector is not in all cases fulfilled. It turns out that in this case often the entanglement imposed by the global constraint of fixed particle number is the limiting factor.Comment: minor changes, 18 pages, 5 figure

A Robust and Universal Metaproteomics Workflow for Research Studies and Routine Diagnostics Within 24 h Using Phenol Extraction, FASP Digest, and the MetaProteomeAnalyzer

The investigation of microbial proteins by mass spectrometry (metaproteomics) is a key technology for simultaneously assessing the taxonomic composition and the functionality of microbial communities in medical, environmental, and biotechnological applications. We present an improved metaproteomics workflow using an updated sample preparation and a new version of the MetaProteomeAnalyzer software for data analysis. High resolution by multidimensional separation (GeLC, MudPIT) was sacrificed to aim at fast analysis of a broad range of different samples in less than 24 h. The improved workflow generated at least two times as many protein identifications than our previous workflow, and a drastic increase of taxonomic and functional annotations. Improvements of all aspects of the workflow, particularly the speed, are first steps toward potential routine clinical diagnostics (i.e., fecal samples) and analysis of technical and environmental samples. The MetaProteomeAnalyzer is provided to the scientific community as a central remote server solution at www.mpa.ovgu.de.Peer Reviewe

The Relationship Between Body Composition and Baseball Performance in Division II Baseball Players

Please view abstract in the attached PDF file

Entrepreneurial visions of the self:Language teaching and learning under neoliberal conditions

In this special issue, we bring together empirical research that takes a critical perspective on the relationship between language learning and individual aspirations for future success. In doing so we aim to initiate a debate on how neoliberal ideology and mode of governance permeate language learning as part of a wider neoliberal project that postulates the ideal of the competitive and self-responsible language learner. The four contributions illustrate how neoliberal desires about entrepreneurial selves play out differently within different social, political, or linguistic contexts. They do not only address different languages individuals supposedly need to teach or acquire for a successful future within a specific context, but also concentrate on the discourses and social relations shaping these entrepreneurial aspirations. Ranging from vocational training in Japan, early education in Singapore, healthcare tourism in India, to higher education in Switzerland, the contributions all illustrate the role of language as part of the struggle to improve either oneself or others. While the research sites illustrate that investments in language are simultaneously promising and risky and as such dependent on local and global linguistic markets, they equally highlight underlying language ideologies and reveal wider structures of inequality that are firmly embedded in local, national and global contexts

Treating hummingbirds as feathered bees : a case of ethological cross-pollination

Hummingbirds feed from hundreds of flowers every day. The properties of these flowers provide these birds with a wealth of information about colour, space and time to guide how they forage. To understand how hummingbirds might use this information, researchers have adapted established laboratory paradigms for use in the field. In recent years, however, experimental inspiration has come less from other birds, and more from looking at other nectar-feeders, particularly honeybees and bumblebees, which have been models for foraging behaviour and cognition for over a century. In a world in which the cognitive abilities of bees regularly make the news, research on the influence of ecology and sensory systems on bee behaviour is leading to novel insights in hummingbird cognition. As methods designed to study insects in the laboratory are being applied to hummingbirds in the field, converging methods can help us identify and understand convergence in cognition, behaviour and ecology.PostprintPeer reviewe

Matrix product decomposition and classical simulation of quantum dynamics in the presence of a symmetry

We propose a refined matrix product state representation for many-body quantum states that are invariant under SU(2) transformations, and indicate how to extend the time-evolving block decimation (TEBD) algorithm in order to simulate time evolution in an SU(2) invariant system. The resulting algorithm is tested in a critical quantum spin chain and shown to be significantly more efficient than the standard TEBD.Comment: 5 pages, 4 figure