Indicators for merge conflicts in the wild: survey and empirical study

While the creation of new branches and forks is easy and fast with modern version-control systems, merging is often time-consuming. Especially when dealing with many branches or forks, a prediction of merge costs based on lightweight indicators would be desirable to help developers recognize problematic merging scenarios before potential conflicts become too severe in the evolution of a complex software project. We analyze the predictive power of several indicators, such as the number, size or scattering degree of commits in each branch, derived either from the version-control system or directly from the source code. Based on a survey of 41 developers, we inferred 7 potential indicators to predict the number of merge conflicts. We tested corresponding hypotheses by studying 163 open-source projects, including 21,488 merge scenarios and comprising 49,449,773 lines of code. A notable (negative) result is that none of the 7 indicators suggested by the participants of the developer survey has a predictive power concerning the frequency of merge conflicts. We discuss this and other findings as well as perspectives thereof.     

Stability radii for positive linear time-invariant systems on time scales

We deal with dynamic equations on time scales, where we characterize the positivity of a system. Uniform exponential stability of a system is determined by the spectrum of its matrix. We investigate the corresponding stability radii with respect to structured perturbations and show that, for positive systems, the complex and the real stability radius coincide.     

In-house and interlaboratory validation of a method for the extraction of DNA from pollen in honey

In this work, the in-house and interlaboratory validation of a DNA extraction method from pollen in an unifloral rape honey as well as several multifloral honeys is described. The amplifiability of plant and rape DNA amplifiable by real-time PCR was used as a parameter for the evaluation of the method. The practical (i.e., relative) limit of detection was used as a tool for assessing the suitability of the extraction method for further GMO analysis. In a collaborative study with 14 participating labs the results of the in-house validation could be confirmed. The amount of amplifiable plant and rape DNA varied depending on the type of honey. For rape honey, a mean practical LOD of 0.12?% was obtained.     

Development and validation of a real-time PCR detection method for celery in food

As from 25 November 2005 onwards, a list of ingredients with known allergenic potential has to be labeled according to Directive 2003/89/EC, including celery and products thereof. In order to provide appropriate detection methods a novel real-time polymerase chain reaction (PCR) system for the specific and sensitive detection of DNA from celery (Apium graveolens) was developed and validated. Specificity was confirmed by testing DNA derived from more than 50 food relevant organisms. Sensitivity was demonstrated on the basis of a calibration curve plotting the corresponding Ct-values against DNA amounts ranging from 1 to 1000 copies. Due to the lack of certified reference material the applicability of the method was assessed by analysis of sausages spiked with defined amounts of grounded celery seed. The limit of detection (LOD) examined exemplarily for emulsion-type sausages was 5–10 mg/kg. Analysis of celery-containing commercial products demonstrated the performance potential and limitations of the new real-time PCR system.     

Two tetraplex real-time PCR for the detection and quantification of DNA from eight allergens in food

According to the EU and Swiss legislation, food has to be labelled for allergens to enable allergic consumers to avoid such food and its products. To provide efficient and reliable methods, two novel quantitative multiplex real-time polymerase chain reaction systems were developed and validated. They simultaneously determine DNA of peanut, hazelnut, celery, soy, egg, milk, almond and sesame, respectively. The tests exhibit good specificity and sensitivity in the range of 0.01%. Due to low DNA amounts, lower sensitivities for egg and milk were obtained. First comparisons of ELISA results with PCR results suggest a qualitative accordance, but a low correlation of quantitative results.     

Qualitative PCR zum Nachweis transgener Kartoffeln mit ver?ndertem St?rkestoffwechsel oder Sch?dlingsresistenz Anhang 8.4 PCR-Nachweis des pHAS3-Konstruktes in Kartoffeln mit ver?ndertem St?rkestoffwechsel (BASF Plant Science GmbH)

METHODENSAMMLUNG DER BUND/L?NDER-AG GENTECHNIK (LAG)

Qualitative PCR zum Nachweis transgener Kartoffeln mit ver?ndertem St?rkestoffwechsel oder Sch?dlingsresistenz Anhang 8.4 PCR-Nachweis des pHAS3-Konstruktes in Kartoffeln mit ver?ndertem St?rkestoffwechsel (BASF Plant Science GmbH)     

Fiberboards Based on Sugarcane Bagasse Lignin and Fibers

Summary: Fiberboards were prepared using phenolic type resins (phenol‐formaldehyde) and sugarcane bagasse fibers. Lignin extracted through an organosolv process from sugarcane bagasse was used as substitute of phenol in phenolic resins from 40 (lignin‐phenol‐formaldehyde) to 100 wt.‐% (lignin‐formaldehyde) substitution. Some of the fibers were chemically modified by oxidation with chlorine dioxide and treatment with furfuryl alcohol (FA), leading to fibers coated with polyfurfuryl alcohol. Thermal analysis (DSC and TGA) of the prepolymers allowed setting up an efficient curing to prepare fiberboards. Impact strength and water absorption were measured showing the importance of the curing pressure to obtain good performance. When chemically modified fibers were used to prepare board samples, enhanced durability against white root fungi is observed, and to a less degree against brown root fungi. Sugarcane bagasse fiberboards were prepared from prepolymers where lignin substituted phenol up to 100%. This replaces these materials in advantageous position, relating to those prepared from phenol‐formaldehyde resins, due to their high content of renewable raw materials. The results obtained are promising for the utilization of sugarcane bagasse as raw materials for preparing fiberboards to be used in tropical areas.

Stabilization of sugarcane bagasse fiberboards made with unmodified and modified (ClO₂ + furfuryl alcohol) fibers and phenolic resin after 8 weeks exposure against fungi.     

Generalized Cohesive Zone Model: incorporating triaxiality dependent failure mechanisms

The present work has been inspired by a presentation given in the preceding conference of this series (T. Siegmund, W. Brocks, Int. J. Fracture, in print). In this study, a modified Gurson Model has been adopted as a reference solution and the response of classic Cohesive Zone Models (CZM) has been evaluated. It has been shown that the conventional CZM in general is not able to predict the influence of the triaxiality on the failure initiation, and that it is not possible to reproduce the expected reference behaviour with a single set of calibration parameters. In the presented framework of modelling, the feature of mode I failure and its transition to mixed mode failure is incorporated within a Generalized Cohesive Zone Model (GCZM; S. Weihe, Dissertation, 1995). Fracture is initiated by a strength criterion while progressive material degradation is based on energy criteria in analogy to Fracture Mechanics. Complete separation due to fracture is obtained when the critical fracture toughness G_f^c has been dissipated, where the actual value of G_f^c is dependent on the predicted failure mode. It is shown that the transition to mixed mode failure allows the GCZM to reproduce the varying contributions of modes I and II over the triaxiality regime realistically.     

Autoantibodies activating human beta1-adrenergic receptors are associated with reduced cardiac function in chronic heart failure

BACKGROUND: Autoantibodies against synthetic peptides of beta-adrenergic receptors have been observed in human cardiomyopathy. However, it has never been shown that such antibodies really interact with native human beta-adrenergic receptors, nor has the clinical impact of such an interaction been investigated in larger groups of patients. METHODS AND RESULTS: We screened 104 patients with dilated or ischemic cardiomyopathy (NYHA functional classes II to IV) and 108 healthy subjects for IgG antibodies reacting with beta-receptor peptides. Such IgGs were further analyzed for binding and functional interactions with native recombinant human beta-adrenergic receptors. Antibodies reacting with synthetic receptor peptides were present in 51% of the patients. However, only a subgroup directed against the second extracellular receptor domain also recognized native human beta-adrenergic receptors situated in a cell membrane. All antibodies of this subgroup impaired receptor ligand binding and enhanced receptor-mediated signaling, which could be blocked by 5 micromol/L bisoprolol in vitro. Their prevalence was 1% in healthy subjects and 10% in ischemic cardiomyopathy, whereas it amounted to 26% in dilated cardiomyopathy and was associated with a significantly poorer left ventricular function. CONCLUSIONS: Our data show that activating autoantibodies against human beta-adrenergic receptors exist in approximately 25% of patients with dilated cardiomyopathy. Counteraction of such autoantibodies might contribute to the beneficial effects of beta-adrenergic receptor blockade in chronic heart failure.