Paradoxical Magnetic Cooling in a Structural Transition Model

In contrast to the experimentally widely used isentropic demagnetization process for cooling to ultra-low temperatures we examine a particular classical model system that does not cool, but rather heats up with isentropic demagnetization. This system consists of several magnetite particles in a colloidal suspension, and shows the uncommon behavior of disordering structurally while ordering magnetically in an increasing magnetic field. For a six-particle system, we report an uncommon structural transition from a ring to a chain as a function of magnetic field and temperature.Comment: 3 pages, 2 figures. For recent information on physics of small systems see http://www.smallsystems.d

Bisulfite sequencing Data Presentation and Compilation (BDPC) web server—a useful tool for DNA methylation analysis

During bisulfite genomic sequencing projects large amount of data are generated. The Bisulfite sequencing Data Presentation and Compilation (BDPC) web interface (http://biochem.jacobs-university.de/BDPC/) automatically analyzes bisulfite datasets prepared using the BiQ Analyzer. BDPC provides the following output: (i) MS-Excel compatible files compiling for each PCR product (a) the average methylation level, the number of clones analyzed and the percentage of CG sites analyzed (which is an indicator of data quality), (b) the methylation level observed at each CG site and (c) the methylation level of each clone. (ii) A methylation overview table compiling the methylation of all amplicons in all tissues. (iii) Publication grade figures in PNG format showing the methylation pattern for each PCR product embedded in an HMTL file summarizing the methylation data, the DNA sequence and some basic statistics. (iv) A summary file compiling the methylation pattern of different tissues, which is linked to the individual HTML result files, and can be directly used for presentation of the data in the internet. (v) A condensed file, containing all primary data in simplified format for further downstream data analysis and (vi) a custom track file for display of the results in the UCSC genome browser

The Origins of Phase Transitions in Small Systems

The identification and classification of phases in small systems, e.g. nuclei, social and financial networks, clusters, and biological systems, where the traditional definitions of phase transitions are not applicable, is important to obtain a deeper understanding of the phenomena observed in such systems. Within a simple statistical model we investigate the validity and applicability of different classification schemes for phase transtions in small systems. We show that the whole complex temperature plane contains necessary information in order to give a distinct classification.Comment: 3 pages, 4 figures, revtex 4 beta 5, for further information see http://www.smallsystems.d

Deceptive signals of phase transitions in small magnetic clusters

We present an analysis of the thermodynamic properties of small transition metal clusters and show how the commonly used indicators of phase transitions like peaks in the specific heat or magnetic susceptibility can lead to deceptive interpretations of the underlying physics. The analysis of the distribution of zeros of the canonical partition function in the whole complex temperature plane reveals the nature of the transition. We show that signals in the magnetic susceptibility at positive temperatures have their origin at zeros lying at negative temperatures.Comment: 4 pages, 5 figures, revtex4, for further information see http://www.smallsystems.d

Phase transitions in magnetic clusters and other finite systems

This cumulative dissertation consists of seven articles dealing with phase transitions of magnetic clusters or other finite systems. We show that phase transitions in finite systems, which can be experimentally seen only in floppy humps of the specific heat or the magnetic susceptibility, can be quantitatively described by an analysis of an optimized estimation of the probability distribution of the system states combined with Landau free energy, or by analyzing the partition function in the complex temperature plane, or other complex-time response functions such as the complex specific heat. We show that new efficient methods, such as the Ferrenberg analysis, not applicable to infinite systems, can be applied to finite systems, even if the systems have more than one external parameter. With an Optimized Multidimensional Data Analysis of histograms produced by canonical Monte Carlo simulations, we are able to compute the phase behaviour of finite magnetic systems over a wide temperature and magnetic field range just by determining observables at a few given temperatures and magnetic fields

The effect of Open Access on Citation Impact

Physics articles self-archived in arXiv have up to 4 times as much citation impact as articles that are not self-archived

Tutorial: OAI

Originally developed as a means for metadata dissemination of preprint and eprint servers, the OAI Protocol for Metadata Harvesting (OAI-PMH) meanwhile has become a widely known solution to connect distributed electronic archives of all kinds. The OAI-PMH owes much of its acceptance not only among experts to its simplicity and the comparatively very low costs of its implementation. After a brief outline of the protocol's genesis and its development to date this tutorial will give an introduction to the main ideas of the OAI-PMH, its general functioning and some protocol details. Then we will deal with special implementation issues for data providers and service providers including both the necessary steps for a local implementation and several examples of freely available and adaptable tools for implementations. The tutorial will also provide an overview of the implementation of a data provider metadata set. Handouts including a glossary of terms will be provided. The tutorial should be attended by persons who are interested in more technical aspects of the OAI Protocol for Metadata Harvesting

Open Access Journal Systems / Online Publications Systems

We will look at Open Journal Systems. GAPworks, a workflow software of the project German Acadamic Publishers (GAP) will be presented. The system allows the setup of a complete publication workflow for publishing institutions including a web-based peer review. The workflow supports different review models, can be configured to meet local requirements, and can also be used as an institutional repository with an embedded OAI Data-Provider. We will also look at the SEER/OJS system of IBICT in order to find areas of overlap as well as differences in the approach. Despite these more technical presentations, we will look at strategies how to set up Open Journals and how academic researches be motivated to contribute their papers to such journals