Multiple exciton generation in nano-crystals revisited: Consistent calculation of the yield based on pump-probe spectroscopy

Multiple exciton generation (MEG) is a process in which more than one exciton is generated upon the absorption of a high energy photon, typically higher than two times the band gap, in semiconductor nanocrystals. It can be observed experimentally using time resolved spectroscopy such as the transient absorption measurements. Quantification of the MEG yield is usu- ally done by assuming that the bi-exciton signal is twice the signal from a single exciton. Herein we show that this assumption is not always justified and may lead to significant errors in the estimated MEG yields. We develop a methodology to determine proper scaling factors to the signals from the transient absorption experiments. Using the methodology we find modest MEG yields in lead chalcogenide nanocrystals including the nanorods

Scene Segmentation Driven by Deep Learning and Surface Fitting

This paper proposes a joint color and depth segmentation scheme exploiting together geometrical clues and a learning stage. The approach starts from an initial over-segmentation based on spectral clustering. The input data is also fed to a Convolutional Neural Network (CNN) thus producing a per-pixel descriptor vector for each scene sample. An iterative merging procedure is then used to recombine the segments into the regions corresponding to the various objects and surfaces. The proposed algorithm starts by considering all the adjacent segments and computing a similarity metric according to the CNN features. The couples of segments with higher similarity are considered for merging. Finally the algorithm uses a NURBS surface fitting scheme on the segments in order to understand if the selected couples correspond to a single surface. The comparison with state-of-the-art methods shows how the proposed method provides an accurate and reliable scene segmentation

New England Medical Center Posterior Circulation Stroke Registry: I. Methods, Data Base, Distribution of Brain Lesions, Stroke Mechanisms, and Outcomes

Among 407 New England Medical Center Posterior Circulation Registry (NEMC-PCR) patients, 59% had strokes without transient ischemic attacks (TIAs), 24% had TIAs before strokes, and 16% had only posterior circulation TIAs. Embolism was the commonest stroke mechanism accounting for 40% of cases (24% cardiac origin, 14% arterial origin, 2% had potential cardiac and arterial sources). In 32%, large artery occlusive lesions caused hemodynamic brain infarction. Stroke mechanisms in the posterior and anterior circulation are very similar. Infarcts most often included the distal posterior circulation territory (rostral brainstem, superior cerebellum and occipital and temporal lobes), while the proximal (medulla and posterior inferior cerebellum) and middle (pons and anterior inferior cerebellum) territories were equally involved. Infarcts that included the distal territory were twice as common as those that included the proximal or middle territories. Most distal territory infarcts were attributable to embolism. Thirty day mortality was low (3.6%). Embolic stroke mechanism, distal territory location, and basilar artery occlusive disease conveyed the worst prognosis

The Prohibition of the Proposed Springer-Prosiebensat.1-Merger: How Much Economics in German Merger Control?

We review the Bundeskartellamt (Federal Cartel Office Germany) decision on the proposed merger between Springer and ProSiebenSat.1 from an economic point of view. In doing so, it is not our goal to analyse whether the controversial decision by the Bundeskar-tellamt has been correct or flawed from a legal point of view. Instead, we analyse whether the economic reasoning in the decision document reflects state-of-the-art economic theory on conglomerate mergers. Regarding such types of mergers, anticompetitive effects either do not occur regularly or are more often than not overcompensated by efficiency gains, so that a standard welfare perspective demands reluctance concerning antitrust interventions. This is particularly true if two-sided markets, like media markets, are involved. However, anticompe-titive conglomerate mergers are not impossible, in particular in neighbouring markets where there is some relationship between the products of the merging companies. In line with the more-economic approach in European merger control, a particular thorough line of argumen-tation, backed with particularly convincing economic evidence, is necessary to justify a pro-hibition of a conglomerate merger from an economic point of view. Against this background, we do not find the reasoning of the Bundeskartellamt entirely convincing and sufficiently strong to justify a prohibition of the proposed combination from an economic perspective. The reasons are that (i) the Bundeskartellamt fails to continuously consider consumer and customer welfare as the relevant standards, (ii) positive efficiency and welfare effects of cross-media strategies are neglected, (iii) in contrast, the competition agency sometimes ap-pears to view profitability of post-merger strategy options to be per se anticompetitive (effi-ciency offence), (iv) the incontestability of the relevant markets is not sufficiently substanti-ated, (v) inconsistencies occur regarding the symmetry of the TV advertising market duopoly versus the unique role of the BILD-Zeitung and (vi) the employment of modern economic instruments appears to be underdeveloped. Thus, we conclude that the Bundeskartellamt has not embraced the European more-economic approach in the analysed decision. However, one can discuss whether economic effects are overcompensated in this case by concerns about a reduction in diversity of opinion and threats to free speech. Similar to the Bundeskartellamt, we do not consider these concerns in our analysis

Zentrifugale (antidrome) Nervenfasern im menschlichen Sehnerven

Sehnerven von zwei Patienten wurden histologisch untersucht, deren zugehörige Retinae einmal 11 und einmal 16 Jahre zuvor operativ entfernt wurden. In beiden Sehnerven wurden gleicherweise noch zahlreiche, feine Nervenfasern erhalten gefunden. Diese Tatsache wird als Beweis für die Existenz zentrifugaler Nervenfasern im Sehnerven des Menschen angesehen.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47364/1/417_2004_Article_BF00684757.pd