Quantum techniques using continuous variables of light

We present schemes for the generation and evaluation of continuous variable entanglement of bright optical beams and give a brief overview of the variety of optical techniques and quantum communication applications on this basis. A new entanglement-based quantum interferometry scheme with bright beams is suggested. The performance of the presented schemes is independent of the relative interference phase which is advantageous for quantum communication applications.Comment: 11 pages, 5 figures; minor correction, accepted versio

Case studies from the biomedical and health systems research activities of the Swiss Tropical Institute in Africa

Neither high theoretical efficacy of disease control tools, nor diagnostic accuracy, nor good compliance, nor adequate coverage can lead on its own to the final goal of community effectiveness. There is a complex relationship between these factors. The different steps in the process leading to effective health care in the community are discussed on the basis of biomedical and health systems research activities of the Swiss Tropical Institute. Schistosomiasis and malaria control provide the background to problems related to the efficacy of tools. In particular, information on the trial of a malaria vaccine candidate (SPf66) is given. Approaches to the rapid, accurate and economical diagnosis of communities at risk are discussed with reference to Schistosoma haematobium and S. mansoni. Health service support projects in Tanzania and Chad are presented to exemplify problems linked to the compliance of users/providers and coverage. Finally, it is shown that community effectiveness depends on the highest possible success rate for each step. This requires the co-operative efforts of all those involved: the scientist, the manager, the community health worker and, last but not least, the community itsel

Reduction of Guided Acoustic Wave Brillouin Scattering in Photonic Crystal Fibers

Guided Acoustic Wave Brillouin Scattering (GAWBS) generates phase and polarization noise of light propagating in glass fibers. This excess noise affects the performance of various experiments operating at the quantum noise limit. We experimentally demonstrate the reduction of GAWBS noise in a photonic crystal fiber in a broad frequency range using cavity sound dynamics. We compare the noise spectrum to the one of a standard fiber and observe a 10-fold noise reduction in the frequency range up to 200 MHz. Based on our measurement results as well as on numerical simulations we establish a model for the reduction of GAWBS noise in photonic crystal fibers.Comment: 4 pages, 7 figures; added numerical simulations, added reference

Numerical Integrators for Highly Oscillatory Hamiltonian Systems: A Review

Numerical methods for oscillatory, multi-scale Hamiltonian systems are reviewed. The construction principles are described, and the algorithmic and analytical distinction between problems with nearly constant high frequencies and with time- or state-dependent frequencies is emphasized. Trigonometric integrators for the first case and adiabatic integrators for the second case are discussed in more detail

Discrimination of Dynamical System Models for Biological and Chemical Processes

In technical chemistry, systems biology and biotechnology, the construction of predictive models has become an essential step in process design and product optimization. Accurate modelling of the reactions requires detailed knowledge about the processes involved. However, when concerned with the development of new products and production techniques for example, this knowledge often is not available due to the lack of experimental data. Thus, when one has to work with a selection of proposed models, the main tasks of early development is to discriminate these models. In this article, a new statistical approach to model discrimination is described that ranks models wrt. the probability with which they reproduce the given data. The article introduces the new approach, discusses its statistical background, presents numerical techniques for its implementation and illustrates the application to examples from biokinetics

Spinon localization in the heat transport of the spin-1/2 ladder compound (C5_5H12_{12}N)2_2CuBr4_4

We present experiments on the magnetic field-dependent thermal transport in the spin-1/2 ladder system (C$_5$H$_{12}$N)$_2$CuBr$_4$. The thermal conductivity $\kappa(B)$ is only weakly affected by the field-induced transitions between the gapless Luttinger-liquid state realized for $B_{c1}< B < B_{c2}$ and the gapped states, suggesting the absence of a direct contribution of the spin excitations to the heat transport. We observe, however, that the thermal conductivity is strongly suppressed by the magnetic field deeply within the Luttinger-liquid state. These surprising observations are discussed in terms of localization of spinons within finite ladder segments and spinon-phonon umklapp scattering of the predominantly phononic heat transport.Comment: 4 pages, 3 figure

Spectral origin of the colossal magnetodielectric effect in multiferroic DyMn2O5

The origin of the colossal magnetodielectric effect in DyMn2O5 [1] has been an outstanding question in multiferroics. Here, we report the activation of the electric dipole mode at 4-5 cm-1 in an applied magnetic field which fully accounts for the CMD effect. We examine two alternative explanations of this mode: an electromagnon and transitions between f-electron levels of Dy3+ ions. The experimental and theoretical evidence supports the electromagnon origin of the CMD effect.Comment: 5 pages, 4 figures, submitted to PR

Holepyris sylvanidis, ein natürlicher Gegenspieler des Amerikanischen Reismehlkäfers Tribolium confusum; Untersuchungen zur Eindringfähigkeit des Parasitoiden in das Nahrungssubstrat seines Wirtes

Zusammenfassung Das Ameisenwespchen Holepyris sylvanidis (Brèthes, 1913) (Hymenoptera, Bethylidae) ist ein natürlicher Gegenspieler des Amerikanischen Reismehlkäfers Tribolium confusum Jacquelin du Val, 1868 (Coleoptera, Tenebrionidae). T. confusum gilt als bedeutender Schädling in der Nahrungsmittelindustrie sowie in gelagerten Getreideprodukten und tritt in Zentraleuropa vorwiegend in Mühlen und Bäckereien auf. Als Ektoparasitoid der T. confusum-Larven muss H. sylvanidis seine Wirte aufspüren, welche sich in ihren Nahrungssubstraten, wie Mehl und Schrot, in unterschiedlicher Tiefe aufhalten können. Diese Arbeit beschäftigte sich daher mit der Fragestellung, ob der Erfolg von H. sylvanidis bei der Wirtssuche von der Lagetiefe der Wirtslarven im Substrat sowie der Art des Substrates abhängig ist. In Laborversuchen wurde jeweils eine mit 10 T. confusum-Larven bestückte, nicht vollständig geschlossene Petrischale auf dem Boden eines Versuchsglases platziert und mit einer 1, 2, 4 oder 8 cm hohen Schicht feinem oder grobem Weizenvollkornschrot bedeckt (überwiegende Partikelgröße: feiner Schrot < 0,2 mm; grober Schrot 1,4 - 3,0 mm). An der Substratoberfläche wurden jeweils 10 H. sylvanidis-Weibchen und 2 Männchen freigelassen. Je Schrotart und Testtiefe erfolgten 15 Versuchswiederholungen. Die T. confusum-Larven waren nicht in der Lage, die Petrischale zu verlassen, konnten aber von den Wespenweibchen heraustransportiert werden. Das Verschleppen der Wirtslarven ist ein für H. sylvanidis typisches Verhalten, das der eigentlichen Parasitierung vorausgeht. Zwei Wochen nach Versuchsbeginn wurde die Anzahl der verschleppten Käferlarven ermittelt, um den Wirtsfindungserfolg der Wespen bestimmen zu können. In beiden Schrotarten nahm der Anteil der von H. sylvanidis gefundenen Wirtslarven mit zunehmender Tiefe ab. In feinem Schrot fanden die Wespenweibchen ihre Wirtslarven bis zu einer Tiefe von 4 cm, in 8 cm Tiefe platzierte Larven wurden nicht mehr gefunden. Im Gegensatz dazu fanden die Parasitoide in grobem Schrot auch die in 8 cm Tiefe ausgebrachten Wirtslarven. Die Ergebnisse deuten darauf hin, dass eine geringe Partikelgröße des Substrates den Wirtsfindungserfolg von H. sylvanidis verringert. In grobem Schrot sowie in dünnen Schichten eines feinen Substrates erscheint die biologische Bekämpfung von T. confusum mit H. sylvanidis dagegen vielversprechend. Stichwörter: Holepyris sylvanidis, Tribolium confusum, Biologische Bekämpfung, Parasitoid, Eindringfähigkeit, Wirtsfindung   Abstract The bethylid wasp Holepyris sylvanidis (Brèthes, 1913) (Hymenoptera: Bethylidae) is an antagonist of the confused flour beetle Tribolium confusum Jacquelin du Val, 1868 (Coleoptera: Tenebrionidae). T. confusum is a severe pest in the food processing industry and in grain products, in Central Europe primarily in flour mills and bakeries. Females of the larval ectoparasitoid H. sylvanidis face the problem to detect hosts that feed in different depths inside a stored product like flour or grist. The study addressed the question whether successful host finding by H. sylvanidis is dependent on the location of host larvae inside the substrate. Furthermore, it was studied whether the type of substrate affects host finding. In laboratory experiments, 10 T. confusum larvae were placed in a Petri dish accessible to the wasps at a depth of 1, 2, 4 or 8 cm inside either fine or coarse ground wholemeal grist of wheat (main particle size: fine grist < 0.2 mm; coarse grist 1.4 - 3.0 mm). 15 replicates per substrate and depth were performed. 10 female and 2 male parasitoids were released on the surface of the substrate. Host larvae were not able to leave the Petri dish, however, they could be pulled outside the dish by female H. sylvanidis. Within the behavioural sequence of parasitisation, pulling away of host larvae is the behaviour typically preceding oviposition. In order to determine the host finding rate by the parasitoid, the number of missing host larvae was counted two weeks after experiments started. In both types of substrates, host finding decreased with increasing depth. In fine grist, larvae were removed from the Petri dish down to 4 cm depth, however, larvae placed at 8 cm depth were not found anymore. In contrast, in coarse grist host larvae were still parasitised at 8 cm depth. The results suggest that decreasing substrate particle size reduces the host finding capability by H. sylvanidis. Nevertheless, H. sylvanidis may be considered a promising candidate for biological control of T. confusum larvae feeding in coarse ground grist and in thin layers of fine ground grist. Keywords: Holepyris sylvanidis, Tribolium confusum, biological control, parasitoid, penetration ability, host findin

Cardiac index monitoring by pulse contour analysis and thermodilution after pediatric cardiac surgery

ObjectivesTo validate a new device (PiCCO system; Pulsion Medical Systems, Munich, Germany), we compared cardiac index derived from transpulmonary thermodilution and from pulse contour analysis in pediatric patients after surgery for congenital heart disease. We performed a prospective clinical study in a pediatric cardiac intensive care unit of a university hospital.MethodsTwenty-four patients who had had cardiac surgery for congenital heart disease (median age 4.2 years, range 1.4-15.2 years) were investigated in the first 24 hours after admission to the intensive care unit. A 3F thermodilution catheter was inserted in the femoral artery. Intracardiac shunts were excluded by echocardiography intraoperatively or postoperatively. Cardiac index derived from pulse contour analysis was documented in each patient 1, 4, 8, 12, 16, 20, and 24 hours after admission to the intensive care unit. Subsequently, a set of three measurements of thermodilution cardiac indices derived by injections into a central venous line was performed and calculated by the PiCCO system.ResultsThe mean bias between cardiac indices derived by thermodilution and those derived by pulse contour analysis over all data points was 0.05 (SD 0.4) L · min · m−2 (95% confidence interval 0.01-0.10). A strong correlation between thermodilution and contour analysis cardiac indices was calculated (Pearson correlation coefficient r = 0.93; coefficient of determination r2 = 0.86).ConclusionsPulse contour analysis is a suitable method to monitor cardiac index over a wide range of indices after surgery for congenital heart disease in pediatric patients. Pulse contour analysis allows online monitoring of cardiac index. The PiCCO device can be recalibrated with the integrated transpulmonary thermodilution within a short time frame

Diverging thermal expansion of the spin-ladder system (C5_5H12_{12}N)2_2CuBr4_4

We present high-resolution measurements of the $c^\star$-axis thermal expansion and magnetostriction of piperidinium copper bromide \hp. The experimental data at low temperatures is well accounted for by a two-leg spin-ladder Hamiltonian. The thermal expansion shows a complex behaviour with various sign changes and approaches a $1/\sqrt{T}$ divergence at the critical fields. All low-temperature features are semi-quantitatively explained within a free fermion model; full quantitative agreement is obtained with Quantum Monte Carlo simulations.Comment: 4 pages, 5 figures; version 2 is slightly shortened and typos are correcte