Wie beeinflusst das Umfeld einer Bank die Effizienz? - Eine DEA-Analyse fuer die Bayerischen Genossenschaftsbanken

Although a huge literature has analysed the efficiency of the banking sector over the last years, only recently the importance to integrate further factors in the analysis has been mentioned. This paper, employing the non-parametric DEA approach to evaluate the efficiency of the Bavarian cooperative banks, investigates the impact of the environmental conditions on the technical efficiency. The results indicate that without consideration of the environment, the technical inefficiency of the banks is overestimated and thus may lead to a wrong evaluation of the quality of the managment.Effizienz, Banken, DEA

Temporal Integration Windows in Neural Processing and Perception Aligned to Saccadic Eye Movements

SummaryWhen processing dynamic input, the brain balances the opposing needs of temporal integration and sensitivity to change. We hypothesized that the visual system might resolve this challenge by aligning integration windows to the onset of newly arriving sensory samples. In a series of experiments, human participants observed the same sequence of two displays separated by a brief blank delay when performing either an integration or segregation task. First, using magneto-encephalography (MEG), we found a shift in the stimulus-evoked time courses by a 150-ms time window between task signals. After stimulus onset, multivariate pattern analysis (MVPA) decoding of task in occipital-parietal sources remained above chance for almost 1 s, and the task-decoding pattern interacted with task outcome. In the pre-stimulus period, the oscillatory phase in the theta frequency band was informative about both task processing and behavioral outcome for each task separately, suggesting that the post-stimulus effects were caused by a theta-band phase shift. Second, when aligning stimulus presentation to the onset of eye fixations, there was a similar phase shift in behavioral performance according to task demands. In both MEG and behavioral measures, task processing was optimal first for segregation and then integration, with opposite phase in the theta frequency range (3–5 Hz). The best fit to neurophysiological and behavioral data was given by a dampened 3-Hz oscillation from stimulus or eye fixation onset. The alignment of temporal integration windows to input changes found here may serve to actively organize the temporal processing of continuous sensory input

Pre‐stimulus alpha‐band power and phase fluctuations originate from different neural sources and exert distinct impact on stimulus‐evoked responses

Ongoing oscillatory neural activity before stimulus onset influences subsequent visual perception. Specifically, both the power and the phase of oscillations in the alpha-frequency band (9–13 Hz) have been reported to predict the detection of visual stimuli. Up to now, the functional mechanisms underlying pre-stimulus power and phase effects on upcoming visual percepts are debated. Here, we used magnetoencephalography recordings together with a near-threshold visual detection task to investigate the neural generators of pre-stimulus power and phase and their impact on subsequent visual-evoked responses. Pre-stimulus alpha-band power and phase opposition effects were found consistent with previous reports. Source localization suggested clearly distinct neural generators for these pre-stimulus effects: Power effects were mainly found in occipital-temporal regions, whereas phase effects also involved prefrontal areas. In order to be functionally relevant, the pre-stimulus correlates should influence post-stimulus processing. Using a trial-sorting approach, we observed that only pre-stimulus power modulated the Hits versus Misses difference in the evoked response, a well-established post-stimulus neural correlate of near-threshold perception, such that trials with stronger pre-stimulus power effect showed greater post-stimulus difference. By contrast, no influence of pre-stimulus phase effects were found. In sum, our study shows distinct generators for two pre-stimulus neural patterns predicting visual perception, and that only alpha power impacts the post-stimulus correlate of conscious access. This underlines the functional relevance of prestimulus alpha power on perceptual awareness, while questioning the role of alpha phase

Gewinnung haploider Stammzellkulturen der Maus für genetische Screens

Haploid mouse embryonic stem cells are a handy tool to investigate loss of function mutations. Furthermore, these cells can contribute to chimeric embryos and can be used to introduce genetic modifications into mouse germ lines. Nevertheless, haploid cell cultures have to be maintained by flow sorting on a regular basis due to spontaneous diploidization. Here we present physical differences between haploid and diploid cells, which can be used in applied cell sorting of haploid cell cultures

Top-Down Control in Contour Grouping

Human observers tend to group oriented line segments into full contours if they follow the Gestalt rule of 'good continuation'. It is commonly assumed that contour grouping emerges automatically in early visual cortex. In contrast, recent work in animal models suggests that contour grouping requires learning and thus involves top-down control from higher brain structures. Here we explore mechanisms of top-down control in perceptual grouping by investigating synchronicity within EEG oscillations. Human participants saw two micro-Gabor arrays in a random order, with the task to indicate whether the first (S1) or the second stimulus (S2) contained a contour of collinearly aligned elements. Contour compared to non-contour S1 produced a larger posterior post-stimulus beta power (15–21 Hz). Contour S2 was associated with a pre-stimulus decrease in posterior alpha power (11–12 Hz) and in fronto-posterior theta (4–5 Hz) phase couplings, but not with a post-stimulus increase in beta power. The results indicate that subjects used prior knowledge from S1 processing for S2 contour grouping. Expanding previous work on theta oscillations, we propose that long-range theta synchrony shapes neural responses to perceptual groupings regulating lateral inhibition in early visual cortex

Wie beeinflußt das Umfeld einer Bank die Effizienz? Eine DEA-Analyse für die Bayerischen Genossenschaftsbanken

Although a huge literature has analysed the efficiency of the banking sector over the last years, only recently the importance to integrate further factors in the analysis has been mentioned. This paper, employing the non-parametric DEA approach to evaluate the efficiency of the Bavarian cooperative banks, investigates the impact of the environmental conditions on the technical efficiency. The results indicate that without consideration of the environment, the technical inefficiency of the banks is overestimated and thus may lead to a wrong evaluation of the quality of the managment.Bei der Effizienzanalyse von Banken haben sich die Arbeiten bislang die Standortfaktoren vollständig vernachlässigt. In der Arbeit soll der Einfluß der Standortfaktoren einer Bank auf das Effizienzniveau untersucht werden, indem eine Integration der Faktoren in ein DEA-Modell unternommen wird. Es zeigt sich, daß die Effizienz der Banken nach einer Berück-sichtigung der Faktoren steigt und damit nur ein Teil der technischen Ineffizienz durch das Management zu verantworten ist. Eine Vernachlässigung der externen Faktoren bei der Bewertung des Managements kann deshalb zu falschen Folgerungen führen

Einfluß der Modellierung auf die Effizienz der Bank - Produktions- und Intermediationsansatz im Vergleich

For the measurment of the efficiency in the banking sector, different approaches to model the production process have been developed. The impact of a chosen approach on the results is not clear so far. In this context, the aim of this study is to compare the inter-mediation approach and the production approach, two widely spread approaches, in analysing the effects on the efficiency of a bank. Using a non-parametric method the efficiency of bavarian cooperative banks is estimated. The results indicate different values with higher results for the intermediation approach than for the production approach.Für die Darstellung des Produktionsprozesses einer Bank gibt es unterschiedliche Mög-lichkeiten. Bisher besteht in der Literatur kein Wissen darüber, in wie weit die unterschiedlichen Ansätze zu übereinstimmenden Ergebnisse in der Effizienz-analyse kommen. In der Arbeit werden mit dem Produktionsansatz und Inter-mediationsanatz, die zwei häufigsten Ansätze in der Literatur zu findenden Ansätze mit Hilfe der Data Envelopment Analysis (DEA) auf ihre Ergebniswirkung untersucht. Es zeigt sich, daß die beiden Ansätze vor allen Dingen für die Skaleneffizienz und die technische Effizienz deutlich voneinander abweichende Ergebnisse liefern

Temporal windows and visual capacity

The present work aims to arrive at a functional understanding of the visual computations within one perceptual instant of time. When perceiving the external world, we feel surrounded by a sensory environment that extends continuously into both space and time. However, the content of conscious thought consists of coherent scenes containing a limited number of discrete objects as an invariant percept within one particular instance of time. Here, vision is investigated as a process that extracts spatio-temporally invariant information about the physical world and at the same time integrates the current perceptual representation into a dynamic stream of visual impressions