Standard super-activation for Gaussian channels requires squeezing

The quantum capacity of bosonic Gaussian quantum channels can be non-additive in a particularly striking way: a pair of such optical-fiber type channels can individually have zero quantum capacity but super-activate each other such that the combined channel has strictly positive capacity. This has been shown in [Nature Photonics 5, 624 (2011)] where it was conjectured that squeezing is a necessary resource for this phenomenon. We provide a proof of this conjecture by showing that for gauge covariant channels a Choi matrix with positive partial transpose implies that the channel is entanglement-breaking. In addition, we construct an example which shows that this implication fails to hold for Gaussian channels which arise from passive interactions with a squeezed environment.Comment: 5 pages, close to published versio

Synthesis and characterization of mesoporic materials containing highly dispersed cobalt

Highly dispersed Co particles in MCM-41 were prepared by direct addition of CoCl2 to the synthesis gel. The small clusters of Co did not sinter during reduction and sulfidation. Incorporation of Co into the MCM-41 lattice was not observed. The addition of Co to the synthesis gel did not alter the structural characteristics of the MCM-41 samples

Influence of slope of rise and event order of aircraft noise events on high resolution actimetry parameters

Zusammenfassung: Starts und Landungen in der Nacht sind bei den meisten Verkehrsflughäfen durch eine Nachtflugsperre eingeschränkt. Die Empfindlichkeit der Bevölkerung, durch Fluglärm im Schlaf gestört zu werden, ist daher zu Randzeiten, also abends und morgens, besonders gross. In einer experimentellen Feldstudie bei Anwohnern in der Umgebung des Flughafens Zürich untersuchten wir die Wirkung von Fluglärmereignissen auf Körperreaktionen vor dem Aufwachen am Morgen. Dabei wurden in den Schlafzimmern der Versuchspersonen zuvor aufgezeichnete Fluglärm-Geräusche abgespielt. Mit einem nichtinvasiven Aufzeichnungsverfahren für schlafphysiologische Parameter (Hochauflösende Aktimetrie-, Herz- und Atemparameter) wurden Körperbewegungen ereigniskorreliert registriert. Die Resultate ergaben, dass vor allem die ersten paar Lärmereignisse am frühen Morgen die stärksten Reaktionen evozierten und diese mit zunehmender Anzahl erlebter Lärmereignisse abnehmen, was vermuten lässt, dass die zuvor erlebte Anzahl Überflüge eine systematische Wirkung hat, insbesondere wenn die Ereignisse innerhalb kurzer Zeitintervalle auftreten. Es zeigte sich auch, dass die Motilität von der Anstiegsgeschwindigkeit des Schallpegels abhängt, steilere Anstiegsflanken - wie sie typischerweise direkt unterhalb von Landeanflugschneisen auftreten - erzeugen stärkere Bewegungsreaktionen. Dies ist im Einklang mit einer neueren Untersuchung über den Zusammenhang zwischen nächtlichem Flug- und Eisenbahnlärm und Aufwachwahrscheinlichkei

Umklapp scattering from spin fluctuations in Copper-Oxides

The $\mathbf k$-dependent electronic momentum relaxation rate due to Umklapp scattering from antiferromagnetic spin fluctuations is studied within a renormalized mean-field approach to an extended $t-J$ model appropriate to YBa$_2$Cu$_3$O$_{7-x}$ and other cuprates. Transport coefficients are calculated in a relaxation time approximation. We compare these results with those obtained with the phenomenological assumption that all scattering processes dissipate momentum. We show that the latter, which violates momentum conservation, leads to quite different magnitudes and temperature dependences of resistivities and Hall coefficients.Comment: replaced by LaTeX file (due to problems with PostScript

The effects of railway noise on sleep medication intake: results from the ALPNAP-study

In the 1980s/90s, a number of socio-acoustic surveys and laboratory studies on railway noise effects have observed less reported disturbance/interference with sleep at the same exposure level compared with other modes of transportation. This lower grade of disturbance has received the label "railway bonus", was implemented in noise legislation in a number of European countries and was applied in planning and environmental impact assessments. However, majority of the studies investigating physiological outcomes did not find the bespoke difference. In a telephone survey (N=1643) we investigated the relationship between railway noise and sleep medication intake and the impact of railway noise events on motility parameters during night was assessed with contact-free high resolution actimetry devices. Multiple logistic regression analysis with cubic splines was applied to assess the probability of sleep medication use based on railway sound level and nine covariates. The non-linear exposure-response curve showed a statistically significant leveling off around 60 dB (A), Lden. Age, health status and trauma history were the most important covariates. The results were supported also by a similar analysis based on the indicator "night time noise annoyance". No railway bonus could be observed above 55 dB(A), Lden. In the actimetry study, the slope of rise of train noise events proved to be almost as important a predictor for motility reactions as was the maximum sound pressure level - an observation which confirms similar findings from laboratory experiments and field studies on aircraft noise and sleep disturbance. Legislation using a railway bonus will underestimate the noise impact by about 10 dB (A), Lden under the conditions comparable with those in the survey study. The choice of the noise calculation method may influence the threshold for guideline setting