Homology of the mapping class group for surfaces of genus 2 with boundary

We report on the computation of the integral homology of the mapping class group of genus g surfaces with one boundary curve and m punctures, when 2g + m is smaller than 6. In particular, it includes the genus 2 case with no or one puncture.Comment: This is the version published by Geometry & Topology Monographs on 29 April 200

The federal funds market, excess reserves, and unconventional monetary policy

Following the bankruptcy of Lehman Brothers, interbank borrowing and lending dropped, whereas reserve holdings of depository institutions skyrocketed, as the Fed injected liquidity into the U.S. banking sector. This paper introduces bank liquidity risk and limited market participation into a real business cycle model with ex ante identical financial intermediaries and shows, in an analytically tractable way, how interbank trade and excess reserves emerge in general equilibrium. Investigating the role of the federal funds market and unconventional monetary policy for the propagation of aggregate real and financial shocks, I find that federal funds market participation is irrelevant in response to standard supply and demand shocks, whereas it matters for uncertainty shocks, i.e. mean-preserving spreads in the cross-section of liquidity risk. Liquidity injections by the central bank can absorb the effects of financial shocks on the real economy, although excess reserves might increase and federal funds might be crowded out, as a side effect

Shape mode analysis exposes movement patterns in biology: flagella and flatworms as case studies

We illustrate shape mode analysis as a simple, yet powerful technique to concisely describe complex biological shapes and their dynamics. We characterize undulatory bending waves of beating flagella and reconstruct a limit cycle of flagellar oscillations, paying particular attention to the periodicity of angular data. As a second example, we analyze non-convex boundary outlines of gliding flatworms, which allows us to expose stereotypic body postures that can be related to two different locomotion mechanisms. Further, shape mode analysis based on principal component analysis allows to discriminate different flatworm species, despite large motion-associated shape variability. Thus, complex shape dynamics is characterized by a small number of shape scores that change in time. We present this method using descriptive examples, explaining abstract mathematics in a graphic way.Comment: 20 pages, 6 figures, accepted for publication in PLoS On

Serial stereotactic biopsy of brainstem lesions in adults improves diagnostic accuracy compared with MRI only.

Objective: The aim of the current prospective study was to analyse the validity of MRI based diagnosis of brainstem gliomas which was verified by stereotactic biopsy and follow-up evaluation as well as to assess prognostic factors and risk profile. Methods: Between 1998 and 2007, all consecutive adult patients with radiologically suspected brainstem glioma were included. The MRI based diagnosis of the lesions was made independently by an experienced neuroradiologist. Histopathological evaluation was performed in all patients from paraffin embedded specimens obtained by multimodal image guided stereotactic serial biopsy technique. Histopathological results were compared with prior radiological assessment. Length of survival was estimated with the Kaplan–Meier method and prognostic factors were calculated using the Cox model. Results: 46 adult patients were included. Histological evaluation revealed pilocytic astrocytoma (n=2), WHO grade II glioma (n=14), malignant glioma (n=12), metastasis (n=7), lymphoma (n=5), cavernoma (n=1), inflammatory disease (n=2) or no tumour/ gliosis (n=3). Perioperative morbidity was 2.5% (n=1). There was no permanent morbidity and no mortality. All patients with ‘‘no tumour’’ or ‘‘inflammatory disease’’ survived. Patients with low grade glioma and malignant glioma showed a 1 year survival rate of 75% and 25%, respectively; the 1 year survival rate for patients with lymphoma or metastasis was 30%. In the subgroup with a verified brainstem glioma, negative predictors for length of survival were higher tumour grade (p=0.002) and Karnofsky performance score (70 (p=0.004). Conclusion: Intra-axial brainstem lesions with a radiological pattern of glioma represent a very heterogeneous tumour group with completely different outcomes. Radiological features alone are not reliable for diagnostic classification. Stereotactic biopsy is a safe method to obtain a valid tissue diagnosis, which is indispensible for treatment decision

Determination of islet cell antibodies using an ELISA system with a preparation of rat insulinoma (RIN A2) cells

An enzyme-linked immunosorbent assay (ELISA) was established for the detection of islet cell antibodies in human sera. The antigen was prepared from rat insulinoma (RIN A2) cells. Cells were dissociated in lysis buffer and the lysate was centrifuged at 100,000 x g. The supernatant was used to coat microtiter ELISA plates (10 micrograms protein/ml in PBS pH 7.2). Non-specific binding sites on the plates were blocked with 2% PBS-BSA. Human test sera were preabsorbed on separate plates using 2% PBS-BSA and incubated on precoated plates at an optimal dilution of 1/10 in 60 mM PBS for 60 min at 37 degrees C. Phosphatase-labeled anti-human IgG serum and phosphatase substrate were applied and the reaction was stopped by adding 3 M NaOH. Out of 90 sera from type I diabetic patients, 47 (52.2%) reacted in the new ELISA whereas none of 15 type II diabetics, 50 sera containing non-islet specific antibodies or 100 normal controls were positive. In the same group of patients, ICA were positive in 63.3%. When both, the ELISA and conventional ICA testing were applied, the number of positives was increased to 83%. The ICA-ELISA with the above described antigen preparation provides a well standardized and reproducible test method which is highly specific for type I diabetes. It may therefore be useful for large screening procedures

Scaling and regeneration of self-organized patterns

Biological patterns generated during development and regeneration often scale with organism size. Some organisms, e.g., flatworms, can regenerate a rescaled body plan from tissue fragments of varying sizes. Inspired by these examples, we introduce a generalization of Turing patterns that is self-organized and self-scaling. A feedback loop involving diffusing expander molecules regulates the reaction rates of a Turing system, thereby adjusting pattern length scales proportional to system size. Our model captures essential features of body plan regeneration in flatworms as observed in experiments.Comment: 5 pages, 3 color figure

The Markovian metamorphosis of a simple turbulent cascade model

Markovian properties of a discrete random multiplicative cascade model of log-normal type are discussed. After taking small-scale resummation and breaking of the ultrametric hierarchy into account, qualitative agreement with Kramers-Moyal coefficients, recently deduced from a fully developed turbulent flow, is achieved.Comment: 6 pages, 2 figure

Cenomanian/Turonian benthic foraminiferal faunas of the Demerara Rise depth transect (ODP Leg 207)

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Sensorfusion und Regelung eines Roboters am kontinuierlich bewegten Band

Der Artikel beschreibt die Montage eines Anbauteils an ein kontinuierlich bewegtes Basisbauteil, dessen Bewegung durch unterschiedliche Sensoren gemessen wird. Dabei werden u. a. die Ergebnisse einer Bildverarbeitung mit den Auslenkungen eines nachgiebigen Kraft- Momentensensors fusioniert. Aus den Bahnpunkten wird dann eine geglättete Solltrajektorie für das Anbauteil bestimmt. Die Regelung des Roboters wird durch Vorsteuerungen ergänzt, die die dynamischen Verzögerungen und Schwingungen von Roboter und Endeffektor prädiktiv kompensieren

Making the best of mixed-field orientation of polar molecules: A recipe for achieving adiabatic dynamics in an electrostatic field combined with laser pulses

We have experimentally and theoretically investigated the mixed-field orientation of rotational-state-selected OCS molecules and we achieve strong degrees of alignment and orientation. The applied moderately intense nanosecond laser pulses are long enough to adiabatically align molecules. However, in combination with a weak dc electric field, the same laser pulses result in nonadiabatic dynamics in the mixed-field orientation. These observations are fully explained by calculations employing, both, adiabatic and non-adiabatic time-dependent models.Comment: 5 pages, 4 figure