Potential Errors and Test Assessment in Software Product Line Engineering

Software product lines (SPL) are a method for the development of variant-rich software systems. Compared to non-variable systems, testing SPLs is extensive due to an increasingly amount of possible products. Different approaches exist for testing SPLs, but there is less research for assessing the quality of these tests by means of error detection capability. Such test assessment is based on error injection into correct version of the system under test. However to our knowledge, potential errors in SPL engineering have never been systematically identified before. This article presents an overview over existing paradigms for specifying software product lines and the errors that can occur during the respective specification processes. For assessment of test quality, we leverage mutation testing techniques to SPL engineering and implement the identified errors as mutation operators. This allows us to run existing tests against defective products for the purpose of test assessment. From the results, we draw conclusions about the error-proneness of the surveyed SPL design paradigms and how quality of SPL tests can be improved.Comment: In Proceedings MBT 2015, arXiv:1504.0192

Disentangling Treatment Effects of Polish Active Labor Market Policies: Evidence from Matched Samples

This paper estimates causal effects of two Polish active labor market policies - Training and Intervention Works - on employment probabilities. Using data from the 18th wave of the Polish Labor Force Survey we discuss three stages of an appropriately designed matching procedure and demonstrate how the method succeeds in balancing relevant covariates. The validity of this approach is illustrated using the estimated propensity score as a summary measure of balance. We implement a conditional difference-in-differences estimator of treatment effects based on individual trinomial sequences of pre-treatment labor market status. Our findings suggest that Training raises employment probability, while Intervention Works seems to lead to a negative treatment effect for men. Furthermore, we find that appropriate subdivision of the matched sample for conditional treatment effect estimation can add considerable insight to the interpretation of results.http://deepblue.lib.umich.edu/bitstream/2027.42/39831/3/wp447.pd

Three functional facets of calbindin D-28k

Many neurons of the vertebrate central nervous system (CNS) express the Ca2+ binding protein calbindin D-28k (CB), including important projection neurons like cerebellar Purkinje cells but also neocortical interneurons. CB has moderate cytoplasmic mobility and comprises at least four EF-hands that function in Ca2+ binding with rapid to intermediate kinetics and affinity. Classically it was viewed as a pure Ca2+ buffer important for neuronal survival. This view was extended by showing that CB is a critical determinant in the control of synaptic Ca2+ dynamics, presumably with strong impact on plasticity and information processing. Already 30 years ago, in vitro studies suggested that CB could have an additional Ca2+ sensor function, like its prominent acquaintance calmodulin (CaM). More recent work substantiated this hypothesis, revealing direct CB interactions with several target proteins. Different from a classical sensor, however, CB appears to interact with its targets both, in its Ca2+-loaded and Ca2+-free forms. Finally, CB has been shown to be involved in buffered transport of Ca2+, in neurons but also in kidney. Thus, CB serves a threefold function as buffer, transporter and likely as a non-canonical sensor

Das Wertpapiererwerbs- und Übernahmegesetz

Das Wertpapiererwerbs- und Übernahmegesetz (WpÜG) schafft für deutsche Zielgesellschaften einen neuen organisierten Markt für die Konzentration von Streubesitz. Der Beitrag analysiert den Regulierungsbedarf aus ökonomischer Sicht, er präsentiert und erläutert die ausgeklügelten Vorschriften für diesen Markt und wirft schließlich eine Reihe ungeklärter Fragen auf. --Agency-Theorie,Anlegerschutz,Pflichtangebot,Übernahmeangebot,Übernahmen,Wertpapiererwerbs- und Übernahmegesetz (WpÜG)

Developmental Increase of Neocortical Presynaptic Efficacy via Maturation of Vesicle Replenishment

The efficacy of neocortical synapses to transmit during bursts of action potentials (APs) increases during development but the underlying mechanisms are largely unclear. We investigated synaptic efficacy at synapses between layer 5 pyramidal neurons (L5PNs) during development, using paired recordings, presynaptic two-photon Ca2+ imaging, and numerical simulations. Our data confirm a developmental increase in paired-pulse ratios (PPRs). Independent of age, Ca2+ imaging revealed no AP invasion failures and linear summation of presynaptic Ca2+ transients, making differences in Ca2+ signaling an unlikely reason for developmental changes in PPR. Cumulative excitatory postsynaptic current (EPSC) amplitudes indicate that neither the size of the readily-releasable pool (RRP) nor replenishment rates were different between age groups, while the time-courses of depression differed significantly. At young synapses, EPSCs depressed rapidly to near steady-state during the first four APs, and synaptic failures (Fsyn) increased from 0 to 30%. At mature synapses this drop was significantly slower and strongly biphasic, such that near steady-state depression was reached not before 18 APs with Fsyn remaining between 0 and 5%. While young synapses reliably transmitted during pairs of APs, albeit with strong depression, mature synapses maintained near 100% transfer efficacy with significantly less depression during high-frequency bursts of APs. Our analysis indicates that at mature synapses a replenishment pool (RepP) is responsible for their high efficacy during bursting activity, while this RepP is functionally immature at young synapses. Hence, our data provide evidence that the functional maturation of a RepP underlies increasing synaptic efficacy during the development of an excitatory cortical synapse

Disentangling Treatment Effects of Active Labor Market Policies: The Role of Labor Force Status Sequences

This paper estimates treatment effects of two active labor market policies – a training program and a wage subsidy scheme – on participants' employment probabilities. The analysis is based on unique data from the 18th wave of the Polish Labor Force Survey containing detailed and extensive individual labor force status histories. We discuss two variants of an exact covariate matching procedure adapted to the specific nature of the data. Our study confirms and reinforces a point raised in recent research (Heckman and Smith 1999, 2004), that pre-treatment labor force status dynamics play a decisive role in determining program participation. We implement a conditional difference-in-differences estimator of treatment effects based on these individual trinomial sequences of pretreatment labor market status. The estimator employs a “moving window” technique that nicely controls for changes in the macroeconomic environment over time. Our findings suggest that training raises individual employment probability, while wage subsidies display negative treatment effects for participants in the Polish case